Contribution of Breed, Cow Weight, and Milk Yield to the Traits of Heifers and Cows in Four Beef Breeding Systems C. F. Fissl and J. W. Wilton
ABSTRACT, Measurements were taken on 210 cows with 409 calvings for weight at weaning, condition at weaning, milk yield, milk fat percentage, milk lactose percentage, milk protein percentage, dry period feed intake, lactation period feed intake, total feed intake, first-service pregnancy rate, pregnancy rate, and days to pregnancy. Measurements were also taken on 183 heifers for first-service pregnancy rate, days to pregnancy, and age a t first calving. The data spanned the years 1980 to 1988; animals belonged to one of four breeding systems: Hereford, small rotation (Angus, Gelbvieh, Pinzgauer, Tarentaisel, large rotation
(Charolais, Maine Anjou, Simmental), and Anguslarge rotation (cows with Angus sires and large rotation dams). Maine Anjou-sired cows had lower annual feed intake and Charolais-sired heifers lower first-service pregnancy rate than the other large-rotation breeds. Gelbvieh-sired cows had lower milk lactose and protein percentages than the other small-rotation breeds. Within breeding system neither cow weight nor milk yield were significantly associated with reproductive traits of cows. No differences among breeding systems in associations between feed intakes and weights or milk yields were detected.
Key Words: Genetics, Crossbreeding, Efficiency
J. Anim. Sci. 1992. 70:3680-3696
Introduction The cow is the primary producing unit in the beef industry. The cow can be characterized by size, milk yield and composition, energy requirements, and reproductive performance. Knowledge of how each breed compares in these characteristics would help producers in selection of breeds for crossbreeding programs to maximize their returns net of costs. Knowledge of how increasing weight and milk yield of cows will affect other characteristics of cows will also aid producers in making replacement selections within breed. Many researchers including Cundiff (19701, Gregory et al. (19791, Laster et al. (19791, Bailey and Moore (19801, Nelson and Beavers (19821, Steffan et al. (19851, Cundiff et al. (19861, McMorris and Wilton (19861, Azzam and Nielsen (19871, Fredeen et al. (19881, Armstrong et al. (19901, and Fiss and
'Agric. Food Dev. Building, 930 Carling Received January Accepted July 23,
Branch, Dairy Div., Sir John Carling Avenue, Ottawa, Ontario, KIA OC5. 13, 1992. 1992.
Wilton (19891 have determined the characteristics of breeds of cattle but none have examined the effect of changing cow weight or milk yield on traits of cows within each breed. The most common approach has been to examine associations between various traits and weight and milk yield of cows across breeds or for one breed only. This approach does not answer the question of whether all breeds have common associations of a variety of traits with cow weight and milk yield. In addition, very few studies have included feed intake as one of the traits measured. The objectives of this study were to determine 11 characteristics of cows of eight breeds of beef cattle within four breeding systems and 2) association of weight and milk yield of cows with other characteristics within those breeding systems.
Materials and Methods The data for this study were obtained from 183 heifers and 216 cows housed at the Elora Beef Cattle Research Centre, Elora, ON from 1980 to 1988. All cows were classified into one of four
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Centre for Genetic Improvement of Livestock, Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
EFFECTS ON
TRAITS OF BEEF COWS
weight of her calf. Excess pregnant heifers were culled according to their adjusted weaning weight. An attempt was made to replace 33% of the cows within each breeding system each year. In 1983, as part of a calf growth trial, 28 calves were implanted with zeranol (Ralgro, Brae Laboratories, Etobicoke, ON, Canada) at an average age of 55 d. Re-implantation occurred at 84-d intervals until four implants were given. A second trial, designed to determine the effect of removal of calves on the reproductive performance of their dams, took place in 1984 and 1985. Forty-eight and 45 calves in 1984 and 1985, respectively, were removed from their dams for 48 h, 3 wk before the start of the breeding season. Traits of interest were weight at weaning, condition a t weaning, milk yield, milk composition (milk fat percentage, milk protein percentage, and milk lactose percentage), feed intake (dry period, lactation period, and annual), reproduction (firstservice pregnancy rate, pregnancy rate, and days to pregnancy) of cows, and reproduction (age at first calving, first-service pregnancy rate, and days to pregnancy) of heifers. Dry period intake was feed consumed from previous weaning to parturition and lactation period intake was feed consumed from parturition to weaning. Annual intake was dry period intake adjusted to 165 d plus lactation period intake adjusted to 200 d. Because heifers were group fed, they were not included in the calculation of dry period and annual feed intakes. Intakes, as ME, were calculated from daily feed intake, on an ingredient basis, times ME of each ingredient. Metabolizable energy content of ingredients was from NRC (1984). Milk yield and constituent percentages were calculated as the average of three daily milk yields. First-service pregnancy was recorded as 0 or 1 for nonpregnant or pregnant to first service and pregnancy as 0 or 1 for pregnant a t pregnancy check. Analyses for heifer pregnancy to first service contained only those heifers that became pregnant, because predicted milk yield was included in the model and nonpregnant heifers did not have a subsequent milk yield. For the same reason, pregnancy rate was not analyzed for heifers. Days to pregnancy was calculated for cows and heifers pregnant at the end of the breeding season as number of days from start of breeding season to pregnancy. The square root transformation was applied to normalize days to pregnancy. Transformed days to pregnancy is referred to as days to pregnancy throughout this study.
Statistical Analysis The full model for all traits of heifers and cows included breeding system (1 to 41, breed of sire of cow within breeding system (1 to 81, breed of
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breeding systems: Hereford, small rotation, large rotation, and Angus-large rotation. Hereford were straightbred Hereford cattle; small rotation was composed of Angus, Gelbvieh, Pinzgauer, and Tarentaise; large rotation of Charolais, Maine Anjou, and Simmental; and Angus-large rotation of animals with an Angus sire and large-rotation dam. The Angus-large rotation arose from the use of Angus sires on large-rotation heifers. The number of heifers and cows available to be bred and number of cow-years (records) in each sirematernal grandsire breed are given in Table 1. The number of sires of cows in each breed are given in Table 2. Because of the low number of records for Angus-sired small-rotation cows, the Angus-sired small-rotation cows were removed from the analysis. Cows and heifers were housed year round in an open-fronted pole barn. Cows had individual electronic headgates to control access to feed, whereas heifers were group fed until shortly before parturition. Cows were fed a diet that consisted of approximately 50% corn silage and 50% haylage on a DM basis. Rations were determined by energy requirements for maintenance, gain, and lactation, and modified to maintain 8 mm of backfat thickness on cows. Adjustments in rations were made at calving and weaning and a t approximately 6-wk intervals between calving and weaning on the basis of ultrasonic measurements of individual cows. In 1980,35 cows were placed on another trial and were fed 70% of their requirements according to NRC (1976)(Wilton et al., 1987). Weight, milk yield and composition, and backfat thickness of cows were recorded at approximately 6-wk intervals during lactation. Milk yield was determined by separating cows and calves early in the morning. Cows were given a 3-mL injection of oxytocin (Medibiotics, Mississauga, ON, Canada) (20 oxytocin units/ml) to enhance milk let down and milked by machine several minutes later. The process was repeated 6 h later to determine a 6-h milk yield. Daily milk yield was four times the 6-h milk yield. At the same time the ultrasonic backfat thickness between the 11th and 12th ribs was determined by the use of a Scanogram (Model 721, Ithaco, Ithaca, NYI. Cows and heifers were all bred by artificial insemination starting in midJune lasting for 60, 50, and 45 d for the 1980 to 1982, 1983 to 1985, and 1986 to 1988 seasons, respectively. Checking for estrus was aided by the use of a surgically deviated marker bull. Cows and heifers were checked for pregnancy between 42 and 120 d after end of the breeding season, and any nonpregnant animals were culled. If excess pregnant cows were available they were culled for, in order of importance, having a Caesarean section at birth, poor udder or feet and legs, and low adjusted weaning
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FISS AND WILTON
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Table 1. Number of records (r),cows (c), and heifers (h) in each sire-maternal grandsire breed group
Breed of sire of cow Breed of maternal grandsire of cow
HH
GV
AN
AL -
LR
SR
HHa
PZ
TA
CH
MA
SM
HH r h
Total
-
-
202 103 71
-
45 21 21
-
11 7 7
AN
r C
h GV r C
-
h PZ r
-
-
C
h TA r
-
C
-
h CH r
1
1 1
C
h MA r
C
h Total r C
h
-
-
*HH = Hereford, SR = small rotation, LR large rotation, AL = Angus-large rotation, AN Pinzgauer, TA = Tarentaise, CH = Charolais, MA = Maine Anjou, and SM Simmental.
maternal grandsire of cow within breeding system (1 to 81, year (1980 to 19881, and age of dam of cow (2,3,4,or 2 5 yr). The model for cows also included age of cow (2, 3, 4, or 2 5 yr), breed of sire of calf, sex of calf (male or female), cow ration (70 or 100°/~ of NRC t197611, and calf trial as classification variables. Breed of sire and grandsire of cow within the small and large rotations were completely cross-classified (Table 21, and both were completely cross-classified with breed of sire of calf (or service sire). Reproduction traits of heifers and cows also included breed of service sire within breeding system (1 to 8) and sex of fetus (male or female) as classification variables. There was only one age of animal class for reproduction traits of
=
Angus, GV
6 3 3 3 40 22
22
0 0 0
48 24 23
20 11
11
48 30 30
21 12 12
409 216 183
C
h SM r
6 0
=
Gelbvieh, PZ
-
heifers. Dry period and annual feed intake had only three age of animal classes (3,4, or 2 5 yr) because individual feed intake was not recorded on heifers. All two-way interactions between classification variables and breed of sire of cow within breeding system were included. Other interactions were not included because of the number of degrees of freedom required for all two-way interactions. Models for all traits of cows also included animal, permanent environment, and residual random effects, and models for reproduction traits of heifers included animal, maternal, and residual random effects. Variance components for the random effects were estimated by derivative free restricted maximum likelihood (Meyer, 1987).
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C
AN
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EFFECTS ON TRAITS OF BEEF COWS
Table 2. Number of sires of heifers and cows represented by breed Number of sires of Heifers cows
-
HHa
SR
LR
AL
HH
AN^
GV
PZ
TA
CH
MA
SM
AN
Total
33 34
1 1
6
7 7
5 5
11 11
10 10
14 15
6
83
6
95
6
-
-
-
Weight of cow a t weaning was included in all models for nonreproduction traits (other than weight) as a covariate. Similarly, condition of cow a t weaning was included in all models for nonreproduction traits (other than cow condition) and milk yield in models of all traits other than milk yield. Age of calf a t weaning was included in all models for nonreproduction traits except dry period and annual feed intake. Lactation and dry period intake also included change in condition from birth to weaning and days dry, respectively, as covariates. Covariates for the reproduction traits of cows were weight of cow immediately postcalving, cow condition immediately postcalving, milk yield, and julian birth date of the calf, whereas julian birth date of the heifer, heifer weight, heifer condition, and heifer milk yield were the covariates for reproduction traits of heifers. Heifer weight and condition were each recorded immediately after first calving, and heifer milk yield was the heifer’s first lactation mean milk yield. Covariates were included in the model as linear and quadratic effects across breeding system, within breeding system, and within sire breed, resulting in eight linearly independent covariates for each independent variable. All traits were analyzed by linear models procedures, producing reduction sums of squares, which were used to remove any insignificant factor a t a 15% level of significance. However, main effects were retained if still included in interactions and linear covariates were retained if their quadratic covariate was still included. Breeding system, sire breed of cow within breeding system, linear cow or heifer weight, and linear milk yield remained in all models. The F-value used to determine the removal of a covariate was based on the reduction due to including the covariate for all breeds with 8 df. The final reduced models are given in Table 3. Least squares means were obtained for breeding systems and sire breeds of cow within breeding systems, and partial regression coefficients were obtained for cow or heifer weight and milk yield. The least squares means were adjusted to the mean value of all covariates within each sire breed of cow. Least squares means and partial
=
Angus, GV
=
Gelbvieh, PZ
=
regression coefficients were compared pairwise by a protected lsd test at a 5 % level of significance.
Results and Discussion Breeding System Means Hereford cows were lightest at weaning, lowest in milk yield, and highest in fat thickness at weaning with large rotation at the opposite extreme (Table 4). Small rotation and Angus-large rotation were not significantly different from large rotation for milk yield or Hereford for cow weight (Table 4). These rankings agree with results from McMorris and Wilton (1986). Hereford had higher milk fat and lactose percentages than did small rotation and large rotation (Table 4); however, milk fat percentage of the cows in all breeding systems was lower than the average of 3.6% reported for Holsteins by NgKwai-Hang et al. (1984) and Monardes and Hayes (1985). The crossbred cattle in this study also produced milk that had a lower fat percentage than found by Mondragon et al. (1983) for beef, dairy x beef, and dairy cattle. The lower milk fat percentage may indicate that incomplete milk-out occurred. If it is assumed that all cows were milked out to the same degree, rankings for milk fat percentage would not be affected, even though absolute values were underestimated. Milk protein and lactose percentages would not be expected to be affected by degree of milk-out. Small-rotation cows were lower for both these constituents than were cows of other systems. Largerotation cows consumed the greatest amount of energy during the dry, lactation, and annual periods, whereas Hereford consumed the least amount of energy (Table 4). Small rotation and Angus-large rotation cows were intermediate in consumption. These results agree with NRC (1984) requirements, providing heavier cattle or cattle that produce higher amounts of milk with more feed than lighter cattle or cattle that produce lower amounts of milk. The actual values were 80% (Hereford) and 9 0% (other breeding systems) of the level given by NRC (1984). The breeding
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*HH Hereford, SR = small rotation, LR = large rotation, AL Angus-large rotation, AN Pinzgauer, TA = Tarentaise, CH = Charolais, MA Maine Anjou, and SM Simmental, bDeleted from analysis.
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FISS AND WILTON
Table 3. Classification variables and covariates included in the final reduced models for traits of heifers and cows Modela
(in addition to BS, and SI and random effects) Classificationb
CovariateC
Weight of cow at weaning Condition of cow at weaning Average daily milk yield Milk composition Fat Lactose Protein Feed intake Dry period Lactation period Annual Reproduction of heifers First-service pregnancy rate Days to pregnancyd Age at first calvingd Reproduction of mature cows First-service pregnancy rate Pregnancy rate Days to pregnancy
AC, AD, RA, YR, SI*YR RA, YR, CT, SI*YR AC, AD, RA, YR, CT. SS, SI+CT, SI*YR, SI*SS
MY, WA, CO CW, MY CW. WA
RA, YR YR, SI*YR RA, YR, SI'YR
CW, MY, CO CW, MY
RA, YR, SI*YR AC, RA, YR, CT, BC, SI'AC, SI*CT, SI*YR RA, YR, SI*YR
CW, MY, DD CW, MY, WA, CO. CC, CC2 CW, MY, CO
AD, YR YR, SF, SI+BC YR, MG
CW, MY CW, MY, CO, JB, JB2 CW, MY, CO, C02, JB
AC, AD, SB AC, AD, SS, SB, SI*AC YR, SB
CW, MY CW, MY, CO CW, MY
CW, MY
'BS = breeding system, SI = breed of sire of cow. AC = age of cow, AD = age of dam of cow or heifer, RA = ration, YR = year, CT = calf trial, SS = sex of suckling calf, BC = maternal grandsire breed, SB service sire breed, quadratic effects are sex of fetus, MG breed of sire of suckling calf, SF denoted by superscript, and *. cCW cow weight, WA age of calf at weaning, CO = cow condition, MY = milk yield, DD = dry days, CC = change in cow condition from birth to weaning, and JB = female's julian birthdate. dQuadratic effect of weight was also included.
-
-
-
-
system rankings agree with the data of McMorris and Wilton (1986) and Armstrong et al. (19901, who analyzed a subset of the data in this study. Other than age at first calving, breeding systems were similar in reproductive performance of heifers and cows (Table 4). This agrees with the findings of Steffan et al. (19851 for Hereford heifer pregnancy rate and services per pregnancy when compared to crossbreds. Other researchers found no differences for first-service pregnancy rate, pregnancy rate (Cundiff, 1970; Bailey and Moore, 1980; Nelson and Beavers, 1982; Cundiff et al., 1986; Fredeen et al., 1988; Fiss and Wilton, 19891, and traits related to days to pregnancy of cows [Azzam and Nielsen, 1987; Fredeen et al., 1988; Fiss and Wilton, 19891. Age a t first calving of Hereford heifers was significantly higher than that of smalland large-rotation heifers. Although Fiss and Wilton (1989) found no significant differences between breeding systems for age at fiist calving on a subset of the data, the same trend was observed. Differences between these two studies may be due to additional data and inclusion in the present study of covariates for heifer milk yield, weight, and julian birth date. Average age of calving was close to or less than 2 yr in all cases. Under the conditions of this research, which
-
included feeding to requirements, there seemed to be little difference in reproductive performance among breeding systems.
Small Rotation Means There were few significant differences in least squares means among small-rotation breeds (Gelbvieh-, Pinzgauer-, and Tarentaise-sired cows) (Table 5). However, Tarentaise-sired cows tended to have lower weights and milk yields than did Gelbvieh- and Pinzgauer-sired cows. Cundiff et al. (19861, however, found Pinzgauer- and Tarentaise sired cows from Angus and Hereford dams similar to each other in weight and milk yield. The Gelbvieh-sired cows from Angus and Hereford dams that Cundiff et al. (1986) studied were 30 kg heavier with milk yields similar to Pinzgauer and Tarentaise. Small-rotationbreeds did not differ significantly in their milk fat percentage. However, Gelbviehsired cows had lower milk lactose and protein percentages than did Pinzgauer- and Tarentaisesired cows (P < .051 (Table 5). The milk lactose and protein percentages of Gelbvieh-sired cows were below the lactose and protein percentages found by Mondragon et al. (19831 for beef, dairy x beef,
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Trait
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EFFECTS ON TRAITS OF BEEF COWS
Table 4. Breeding system least squares means (LSM) and standard errors (SEI for traits of heifers and cows
Trait
548' 9.37b 4.17' 3.31b 5.2Qb 3.41bC 2.375' 3,342' 5,727'
SE
LSM
8
.50 .31
561' 7.09' 7.74b
.13 .05 .06 44 317 63
SE 15 .70 .58
67Eb 3.21d 8.85b
.l6 .13 .I1
2.45' 4.94c 3.54b
2.58' 4.38' 3.25' 2,702' 4,016' 7,052'
LSM
3,020b 4,804b 7,748b
106 29 1 149
66.7 4.87 735b
12.9 .33 3
65.8 5.73 715'
9.5
45.6 85.5 5.77
7.8 8.8 .6 1
59.9 78.6 5.81
9.7 8.8 .99
BO 8
54.9 5.48 717' 73.2 82.0 6.49
SE
LSM
11
.56 .40 .17 .09 .08
69 157 107
586' 7.31' 7.18b
2.8EbC 4.99b' 3.61bC 2,954bc 3,817' 7,235'
SE 20
.e2 31 .23 .20 .17 121 393 176
.81
62.3 4.34 724bC
14.1 .86 9
9.7 8.9 .85
68.9 91.0 7.29
14.7 14.0 1.44
12.4
6
&H = Hereford, SR = small rotation, LR = large rotation, and AL = Angus-large rotation (cows with Angus sires, large rotation dams). b,c-dMeans in same row with no common superscripts differ Ip e .051.
and dairy cattle and the protein percentage of Holsteins found by Ng-Kwai-Hang et al. (1984) and Monardes and Hayes (1985). This difference for Gelbvieh-sired cows is difficult to explain, no outlier values were found. Gelbvieh- and Pinzgauer-sired cows had similar feed intakes during the dry period, both were lower than Tarentaise-sired cows (Table 51. During the lactation period and annually, the smallrotation breeds were similar in feed intakes, although Gelbvieh-sired cows tended to consume more energy than the other small-rotation breeds during lactation and less energy annually. Annual feed intake was not the sum of dry and lactation periods because of the exclusion of first-parity records from both dry and annual intake analyses. Laster et al. (19791 and Gregory et al. (19791 found Gelbvieh, Pinzgauer, and Tarentaise to have different ages a t puberty but similar pregnancy rates in heifers. Cundiff et al. (19861 reported pregnancy rates of cows to be similar for these three breeds. In the present study, no significant differences were found in the reproductive performance of the small rotation breeds (Table 5). However, Gelbvieh-sired heifers tended to have better reproductive performance with higher firstservice pregnancy rate and lower days to preg nancy and age at first calving. Gelbvieh-sired cows tended to have poorer reproductive performance with lower first service and overall pregnancy rates and higher days to pregnancy. Over all reproductive traits studied, Pinzgauer tended to have the best reproductive performance of the
small-rotation breeds, except for days to preg nancy in heifers and age a t first calving. Trends for days to pregnancy and age a t first calving should be similar because days to pregnancy measures length of time from start of breeding season to conception.
Large Ro tu tion Means The large-rotation breeds (Charolais-, Maine Anjou-, and Simmental-sired cows) had similar weights, milk yields, and conditions a t weaning (Table 6). Charolais and Simmental have been found to be similar in weight by Cundiff et al. (19861. In two studies that included Maine Anjou and either Charolais or Simmental (Cundiff et al., 1986; Petit and Lienard, 19881, Maine Anjou was also found similar in weight to Charolais and Simmental. Generally, Charolais have been found to produce less milk than Simmental (Notter et al., 1978; Bowden, 1980; Cundiff et al., 1986). However, Jenkins and Ferrell (19841 found no significant differences between milk yield of Charolais- and Simmental-sired cows as in this study. Fredeen et al. (19881 found milk production of Charolais and Simmental depended on the environment. Charolais produced less than Simmental on pasture and equivalent to Simmental under intensive management. Possible reactions for Charolais producing the same amount of milk as Simmental in this study may be persistency differences depending on feed availability, genetic change, or sample differences. There were no detectable
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Cow wt a t weaning, kg Cow condition a t weaning, mm Milk yield, kg/d Milk composition, % Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, k Days to pregnancy, dd Age a t first calving, d cows First-service pregnancy rate, % Pregnancy rate, % Days to pregnancy, dd
LSM
AL
LR
SR
HHa
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Table 5. Least squares means (LSM)and standard errors (SE) for characteristics of heifers and cows of the small rotation breeds Sire breed of cow PZ
GVa
Trait
SE
LSM
57 1 6.29 8.36
21 1.16 .98
2.58 2.92' 2.40'
.24 .21 .17
2,553' 4,168 6,818
150 430 274
572 7.00 8.23
SE 23 1.17 1.01
2.61 5.14b 3.66b 2,574bC 3,855 7,146
LSM
.27 .19 .17 220 392 274
540 7.98 6.64 2.55 5.10b 3.6eb 2,980b 4,025 7,193
SE 27 .94 .99 .25 .27 .22 155 573 287
69.9 5.60 702
14.7 .70 10
67.4 6.32 728
14.4 1.04 13
60.1 5.25 714
15.5 1.09 9
50.6 69.3 7.24
13.5 13.3 1.37
73.1 84.1 4.59
13.4 12.0 1.41
56.0 82.5 5.50
15.0 14.3 1.35
&GV = Gelbvieh-sired, PZ = Pinzgauer-sired. and TA = Tarentaise-sired. bscMeans in same row with no common superscripts differ (P c .05).
differences in milk component percentages among breeds (Table 61, although a n insignificant difference in milk fat percentage of . 5 % between Maine Anjou- and Simmental-sired cows was estimated. Bowden (1980) and Fredeen et al. (19881 also found no differences in milk fat percentage between Charolais and Simmental. Bowden (19801 found that Charolais had a higher protein percentage than did Hereford and Angus cows when milked 14 wk into lactation but not at 6 or 12 wk into lactation. Fredeen et al. (1988) found no differences in milk protein percentages averaged over the lactation. There were no differences detected in intakes during the lactation period for Charolais-, Maine Anjou-, and Simmental-sired cows or between Charolais- and. Simmental-sired cows during the dry period or annually. In this study, Maine Anjousired cows had significantly lower feed consumption than Charolais-sired cows in the dry period, and Charolais- and Simmental-sired cows annually, even though Maine Anjou-sired cows were not significantly different from Charolais- and Simmental-sired cows in either weight or milk production (Table 8). According to NRC (19841, feed intake of cattle is dependent on weight and milk yield, suggesting all large-rotation breeds should have consumed a n equal amount of feed during all periods. Possible reasons for the reduction in feed intake of the Maine Anjou-sired cows are that
their temperament may be better suited for confinement housing, the Maine Anjou-sired cows may be more efficient than Charolais- and Simmental-sired cows, or the sample of cattle chosen. Warwick and Cobb (19751, in a review, also indicated that there is genetic variation between breeds in voluntary feed intake. Fredeen et al. (1987)also found no differences between dry period intake for Charolais and Simmental cows, and Bowden (1980) found no difference in lactation period intake for Charolais and Simmental cows. Charolais-sired heifers had significantly lower first-service pregnancy rates of heifers than the other large-rotation breeds with no other significant differences among Charolais-, Maine Anjou-, and Simmental-sired heifers and cows for reproductive traits (Table 6). Maine Anjou-sired heifers and cows tended to have the best reproductive performance with higher heifer and cow firstservice pregnancy rate, higher cow pregnancy rate, lower heifer and cow days to pregnancy, and lower age at first calving. Cundiff et al. (1986) also reported that Maine Anjou had a slightly higher pregnancy rate than Charolais and Simmental. Laster et al. (1976) found Charolais and Simmental to have heifer calving rates similar to Hereford and Angus, and Maine Anjou to have a higher heifer pregnancy rate than Hereford and Angus, although not significantly so.
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Weight of cow a t weaning, kg Condition of cow a t weaning, mm Milk yield, kg/d Milk composition, YO Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, YO Days to pregnancy, dd Age at first calving, d cows First-service pregnancy, % Pregnancy rate, % Days to pregnancy, dd
LSM
TA
EFFECTS ON
TRAITS OF BEEF COWS
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Table 6 . Least squares means (LSM) and standard errors (SE) for characteristics of heifers and cows of the large rotation breeds Site breed of cow CHa Trait
LSM
SM
MA
SE
LSM
SE
LSM
SE
~
cows First-service pregnancy rate, YO Pregnancy rate, Or6 Days to pregnancy, dd
684 3.63 9.04 2.35 4.91 3.49 3,24Eb 4,606
8,100b
19 .66
686 3.07 8.85
.22 .15 .13
2.23 5.00 3.81
.81
111 267 164
31.8' 7.01 715
14.9 1.24
76.8 80.7 8.85
13.6 12.8 1.09
8
2,772' 4,083 7,364'
15
.81 .57 .22 .13 .ll 105 196 168
664 2.92 8.05
18 .77 .56
2.76 4.92 3.51
.27
3,03QbC 4,923 7,781'
.10
.oo 85 102 132
69.4b 4.34 710
15.6 1.03 13
63.5b 5.08 727
14.1 .65 8
77.6 94.2 5.51
12.3 11.8 1.21
65.3 71.0 7.11
10.2 9.9 .82
&CH = Charolaissired, MA = Maine Anjou-sired, and SM = Simmental-sired. bicMeans in same row with no common superscripts differ (P < .05).
Cow Weight Generally, increasing cow weights were associated with increases in cow condition, milk yield, and feed intake within the Hereford, smallrotation, or large-rotation breeding systems lTable 71. The positive partial regression coefficient for condition on cow weight at weaning is contrary to the results for breeding systems in which largerotation cattle (heavy weights) were thinner than the other breeding systems (lighter weights). Onks et al. (19751,Marshall et al. (19781, Anderson et al. (19831,and McMorris and Wilton (1986)all found a positive association between cow weight and feed intakes across breeds both with and without breed accounted for by the model, whereas significant associations were found only for the lactation and annual periods for Hereford in the present study. The lack of a significant association between cow weight and reproductive tracts (Table 7) was also found by Fiss and Wilton (1989). However, cow first-service and overall pregnancy rate did tend to decrease with increasing weight of cow in all breeding systems. Associations between weight of cow and other traits were of similar magnitude in each of the crossbred breeding systems. However, Hereford cows usually had associations between weight and other traits that were different from crossbreds. For milk yield, the association with cow weight
was negative and significantly different from the other breeding systems. This difference between Hereford and the other breeding systems may be a breed effect, due to the physical capacity of the animals, or due to the greater condition of the heavier Hereford cows. Milk composition increased with increases in cow weight for Hereford (Table 7) but not other breeding systems. However, the changes for Hereford were small and may reflect a decrease in milk yield with a concomitant increase in milk constituents. Breeding systems did not differ for associations between cow weight and feed intake or reproductive performance. However, Hereford was the only breeding system with significant increases in lactation and annual feed intake.
Milk Yield No association between milk yield and condition was detected across breeding systems (Table 8). The lack of association between condition and milk yield was expected because cows were fed to production requirements. For cow weight and milk yield, breeding systems followed the same trends in association as reported in the cow weight section, negative coefficients for Hereford, and positive or insignificant for the other breeding systems. No significant associations between milk yield and feed intake, other than annual intakes
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Weight of cow at weaning, kg Condition of cow at weaning, mm Milk yield, kg/d Milk composition, % Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, VO Days to pregnancy, dd Age at first calving, d
3694
FISS AND WILTON
Table 7. Breeding system partial regression coefficients (b) and standard errors (SE) for characteristics of heifers and cows on weight of cow at weaninga H H ~ Trait
LR
b
SE
b
SE
b
,204'' -.O 15'*d
.029 .020
.140' .07 1
.059 .040
.105** .074*'
.045 .031
.025
.010 ,000 .005
.018 .012 .010
.004 .009
.015 .011 .009
,008
.009 -1.4 12.0'' 12.4.
4.0 4.5
0.0
.05
1.22
-.008
.004 .014 20.1 -18.5 -44.7
48.5 14.4 28.1 1.20
-1.10
SE
-.006 4.4 14.7 27.8
9.5 10.1 14.8
1.07
-1.06
,037 ,000
.139* .002
.OB1 ,001
.030 -.002'
,080
-.ooo 1.05" -.004
.37 .004
-.07 .045**
.70 ,010
.81 -.002
.82 .o 11
-32 -.57 -.029
.53 .52 .034
1.19 1.11 .113
-.48 -.09
.75 39
.04 1
-1.04 -.8 1 -.037
-
-
&per 10 kg. small rotation, and LR large rotation. bHH = Hereford rotation, SR c.dPartial regression coefficients in same row with no common superscript differ [P *H,:b = 0, P < .05. **P < .01.
.001
.075
.088
,051.
Table 8. Breeding system partial regression coefficients (b) and standard errors (SE) for characteristics of heifers and cows on milk yielda H H ~ Trait
b ~~
~~~~~
Weight of cow at weaning, kg Condition of cow at weaning, mm Milk composition, oh Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, 96 Days to pregnancy, dd Age at first calving, d cows First-service pregnancy rate, 010 Pregnancy rate, O/O Days to pregnancy, dd
~~~
SR SE
LR
b
SE
-4.24*d -.203
1.05 ,104
-3.0Ed .I20
3.79 .190
,158.' ,000 -.025
,035 .02 1 ,017
.020 .007
.050 .039 ,031
20.3 17.9 38.2
12.9 14.2 19.4
-.068*
-18.5 10.1 141.P
138.9 44.7 02.2
.01.
SE
7.34 **c -.059
2.50 .147
,082 -.014 -.019 -5.1 25.4 24.3
.050 .039 .030 28.9 29.2 42.5
-4.70 ,320" 4.17**cd
4.18 .lo9 1.09
-2.52 .317 7.82**'
4.02 ,290 2.70
-4.92 -.040 1.12Cd
3.94 2.13 2.83
-1.08
1.82 1.55 ,025
0.4 1 1.63 -.095
3.72 3.40 ,311
-1.55 2.43 -.022
2.79 2.40 .I38
-.E9 ,039
"per 1 kg/d. bHH = Hereford, SR = small rotation, and LR = large rotation. 'VdPartial regression coefficients in same row with no common superscript differ (P < .05). 'H,:b = 0, P < .05.
**P
ABSTRACT, Measurements were taken on 210 cows with 409 calvings for weight at weaning, condition at weaning, milk yield, milk fat percentage, milk lactose percentage, milk protein percentage, dry period feed intake, lactation period feed intake, total feed intake, first-service pregnancy rate, pregnancy rate, and days to pregnancy. Measurements were also taken on 183 heifers for first-service pregnancy rate, days to pregnancy, and age a t first calving. The data spanned the years 1980 to 1988; animals belonged to one of four breeding systems: Hereford, small rotation (Angus, Gelbvieh, Pinzgauer, Tarentaisel, large rotation
(Charolais, Maine Anjou, Simmental), and Anguslarge rotation (cows with Angus sires and large rotation dams). Maine Anjou-sired cows had lower annual feed intake and Charolais-sired heifers lower first-service pregnancy rate than the other large-rotation breeds. Gelbvieh-sired cows had lower milk lactose and protein percentages than the other small-rotation breeds. Within breeding system neither cow weight nor milk yield were significantly associated with reproductive traits of cows. No differences among breeding systems in associations between feed intakes and weights or milk yields were detected.
Key Words: Genetics, Crossbreeding, Efficiency
J. Anim. Sci. 1992. 70:3680-3696
Introduction The cow is the primary producing unit in the beef industry. The cow can be characterized by size, milk yield and composition, energy requirements, and reproductive performance. Knowledge of how each breed compares in these characteristics would help producers in selection of breeds for crossbreeding programs to maximize their returns net of costs. Knowledge of how increasing weight and milk yield of cows will affect other characteristics of cows will also aid producers in making replacement selections within breed. Many researchers including Cundiff (19701, Gregory et al. (19791, Laster et al. (19791, Bailey and Moore (19801, Nelson and Beavers (19821, Steffan et al. (19851, Cundiff et al. (19861, McMorris and Wilton (19861, Azzam and Nielsen (19871, Fredeen et al. (19881, Armstrong et al. (19901, and Fiss and
'Agric. Food Dev. Building, 930 Carling Received January Accepted July 23,
Branch, Dairy Div., Sir John Carling Avenue, Ottawa, Ontario, KIA OC5. 13, 1992. 1992.
Wilton (19891 have determined the characteristics of breeds of cattle but none have examined the effect of changing cow weight or milk yield on traits of cows within each breed. The most common approach has been to examine associations between various traits and weight and milk yield of cows across breeds or for one breed only. This approach does not answer the question of whether all breeds have common associations of a variety of traits with cow weight and milk yield. In addition, very few studies have included feed intake as one of the traits measured. The objectives of this study were to determine 11 characteristics of cows of eight breeds of beef cattle within four breeding systems and 2) association of weight and milk yield of cows with other characteristics within those breeding systems.
Materials and Methods The data for this study were obtained from 183 heifers and 216 cows housed at the Elora Beef Cattle Research Centre, Elora, ON from 1980 to 1988. All cows were classified into one of four
3686
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Centre for Genetic Improvement of Livestock, Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
EFFECTS ON
TRAITS OF BEEF COWS
weight of her calf. Excess pregnant heifers were culled according to their adjusted weaning weight. An attempt was made to replace 33% of the cows within each breeding system each year. In 1983, as part of a calf growth trial, 28 calves were implanted with zeranol (Ralgro, Brae Laboratories, Etobicoke, ON, Canada) at an average age of 55 d. Re-implantation occurred at 84-d intervals until four implants were given. A second trial, designed to determine the effect of removal of calves on the reproductive performance of their dams, took place in 1984 and 1985. Forty-eight and 45 calves in 1984 and 1985, respectively, were removed from their dams for 48 h, 3 wk before the start of the breeding season. Traits of interest were weight at weaning, condition a t weaning, milk yield, milk composition (milk fat percentage, milk protein percentage, and milk lactose percentage), feed intake (dry period, lactation period, and annual), reproduction (firstservice pregnancy rate, pregnancy rate, and days to pregnancy) of cows, and reproduction (age at first calving, first-service pregnancy rate, and days to pregnancy) of heifers. Dry period intake was feed consumed from previous weaning to parturition and lactation period intake was feed consumed from parturition to weaning. Annual intake was dry period intake adjusted to 165 d plus lactation period intake adjusted to 200 d. Because heifers were group fed, they were not included in the calculation of dry period and annual feed intakes. Intakes, as ME, were calculated from daily feed intake, on an ingredient basis, times ME of each ingredient. Metabolizable energy content of ingredients was from NRC (1984). Milk yield and constituent percentages were calculated as the average of three daily milk yields. First-service pregnancy was recorded as 0 or 1 for nonpregnant or pregnant to first service and pregnancy as 0 or 1 for pregnant a t pregnancy check. Analyses for heifer pregnancy to first service contained only those heifers that became pregnant, because predicted milk yield was included in the model and nonpregnant heifers did not have a subsequent milk yield. For the same reason, pregnancy rate was not analyzed for heifers. Days to pregnancy was calculated for cows and heifers pregnant at the end of the breeding season as number of days from start of breeding season to pregnancy. The square root transformation was applied to normalize days to pregnancy. Transformed days to pregnancy is referred to as days to pregnancy throughout this study.
Statistical Analysis The full model for all traits of heifers and cows included breeding system (1 to 41, breed of sire of cow within breeding system (1 to 81, breed of
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breeding systems: Hereford, small rotation, large rotation, and Angus-large rotation. Hereford were straightbred Hereford cattle; small rotation was composed of Angus, Gelbvieh, Pinzgauer, and Tarentaise; large rotation of Charolais, Maine Anjou, and Simmental; and Angus-large rotation of animals with an Angus sire and large-rotation dam. The Angus-large rotation arose from the use of Angus sires on large-rotation heifers. The number of heifers and cows available to be bred and number of cow-years (records) in each sirematernal grandsire breed are given in Table 1. The number of sires of cows in each breed are given in Table 2. Because of the low number of records for Angus-sired small-rotation cows, the Angus-sired small-rotation cows were removed from the analysis. Cows and heifers were housed year round in an open-fronted pole barn. Cows had individual electronic headgates to control access to feed, whereas heifers were group fed until shortly before parturition. Cows were fed a diet that consisted of approximately 50% corn silage and 50% haylage on a DM basis. Rations were determined by energy requirements for maintenance, gain, and lactation, and modified to maintain 8 mm of backfat thickness on cows. Adjustments in rations were made at calving and weaning and a t approximately 6-wk intervals between calving and weaning on the basis of ultrasonic measurements of individual cows. In 1980,35 cows were placed on another trial and were fed 70% of their requirements according to NRC (1976)(Wilton et al., 1987). Weight, milk yield and composition, and backfat thickness of cows were recorded at approximately 6-wk intervals during lactation. Milk yield was determined by separating cows and calves early in the morning. Cows were given a 3-mL injection of oxytocin (Medibiotics, Mississauga, ON, Canada) (20 oxytocin units/ml) to enhance milk let down and milked by machine several minutes later. The process was repeated 6 h later to determine a 6-h milk yield. Daily milk yield was four times the 6-h milk yield. At the same time the ultrasonic backfat thickness between the 11th and 12th ribs was determined by the use of a Scanogram (Model 721, Ithaco, Ithaca, NYI. Cows and heifers were all bred by artificial insemination starting in midJune lasting for 60, 50, and 45 d for the 1980 to 1982, 1983 to 1985, and 1986 to 1988 seasons, respectively. Checking for estrus was aided by the use of a surgically deviated marker bull. Cows and heifers were checked for pregnancy between 42 and 120 d after end of the breeding season, and any nonpregnant animals were culled. If excess pregnant cows were available they were culled for, in order of importance, having a Caesarean section at birth, poor udder or feet and legs, and low adjusted weaning
3687
FISS AND WILTON
3688
Table 1. Number of records (r),cows (c), and heifers (h) in each sire-maternal grandsire breed group
Breed of sire of cow Breed of maternal grandsire of cow
HH
GV
AN
AL -
LR
SR
HHa
PZ
TA
CH
MA
SM
HH r h
Total
-
-
202 103 71
-
45 21 21
-
11 7 7
AN
r C
h GV r C
-
h PZ r
-
-
C
h TA r
-
C
-
h CH r
1
1 1
C
h MA r
C
h Total r C
h
-
-
*HH = Hereford, SR = small rotation, LR large rotation, AL = Angus-large rotation, AN Pinzgauer, TA = Tarentaise, CH = Charolais, MA = Maine Anjou, and SM Simmental.
maternal grandsire of cow within breeding system (1 to 81, year (1980 to 19881, and age of dam of cow (2,3,4,or 2 5 yr). The model for cows also included age of cow (2, 3, 4, or 2 5 yr), breed of sire of calf, sex of calf (male or female), cow ration (70 or 100°/~ of NRC t197611, and calf trial as classification variables. Breed of sire and grandsire of cow within the small and large rotations were completely cross-classified (Table 21, and both were completely cross-classified with breed of sire of calf (or service sire). Reproduction traits of heifers and cows also included breed of service sire within breeding system (1 to 8) and sex of fetus (male or female) as classification variables. There was only one age of animal class for reproduction traits of
=
Angus, GV
6 3 3 3 40 22
22
0 0 0
48 24 23
20 11
11
48 30 30
21 12 12
409 216 183
C
h SM r
6 0
=
Gelbvieh, PZ
-
heifers. Dry period and annual feed intake had only three age of animal classes (3,4, or 2 5 yr) because individual feed intake was not recorded on heifers. All two-way interactions between classification variables and breed of sire of cow within breeding system were included. Other interactions were not included because of the number of degrees of freedom required for all two-way interactions. Models for all traits of cows also included animal, permanent environment, and residual random effects, and models for reproduction traits of heifers included animal, maternal, and residual random effects. Variance components for the random effects were estimated by derivative free restricted maximum likelihood (Meyer, 1987).
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C
AN
3689
EFFECTS ON TRAITS OF BEEF COWS
Table 2. Number of sires of heifers and cows represented by breed Number of sires of Heifers cows
-
HHa
SR
LR
AL
HH
AN^
GV
PZ
TA
CH
MA
SM
AN
Total
33 34
1 1
6
7 7
5 5
11 11
10 10
14 15
6
83
6
95
6
-
-
-
Weight of cow a t weaning was included in all models for nonreproduction traits (other than weight) as a covariate. Similarly, condition of cow a t weaning was included in all models for nonreproduction traits (other than cow condition) and milk yield in models of all traits other than milk yield. Age of calf a t weaning was included in all models for nonreproduction traits except dry period and annual feed intake. Lactation and dry period intake also included change in condition from birth to weaning and days dry, respectively, as covariates. Covariates for the reproduction traits of cows were weight of cow immediately postcalving, cow condition immediately postcalving, milk yield, and julian birth date of the calf, whereas julian birth date of the heifer, heifer weight, heifer condition, and heifer milk yield were the covariates for reproduction traits of heifers. Heifer weight and condition were each recorded immediately after first calving, and heifer milk yield was the heifer’s first lactation mean milk yield. Covariates were included in the model as linear and quadratic effects across breeding system, within breeding system, and within sire breed, resulting in eight linearly independent covariates for each independent variable. All traits were analyzed by linear models procedures, producing reduction sums of squares, which were used to remove any insignificant factor a t a 15% level of significance. However, main effects were retained if still included in interactions and linear covariates were retained if their quadratic covariate was still included. Breeding system, sire breed of cow within breeding system, linear cow or heifer weight, and linear milk yield remained in all models. The F-value used to determine the removal of a covariate was based on the reduction due to including the covariate for all breeds with 8 df. The final reduced models are given in Table 3. Least squares means were obtained for breeding systems and sire breeds of cow within breeding systems, and partial regression coefficients were obtained for cow or heifer weight and milk yield. The least squares means were adjusted to the mean value of all covariates within each sire breed of cow. Least squares means and partial
=
Angus, GV
=
Gelbvieh, PZ
=
regression coefficients were compared pairwise by a protected lsd test at a 5 % level of significance.
Results and Discussion Breeding System Means Hereford cows were lightest at weaning, lowest in milk yield, and highest in fat thickness at weaning with large rotation at the opposite extreme (Table 4). Small rotation and Angus-large rotation were not significantly different from large rotation for milk yield or Hereford for cow weight (Table 4). These rankings agree with results from McMorris and Wilton (1986). Hereford had higher milk fat and lactose percentages than did small rotation and large rotation (Table 4); however, milk fat percentage of the cows in all breeding systems was lower than the average of 3.6% reported for Holsteins by NgKwai-Hang et al. (1984) and Monardes and Hayes (1985). The crossbred cattle in this study also produced milk that had a lower fat percentage than found by Mondragon et al. (1983) for beef, dairy x beef, and dairy cattle. The lower milk fat percentage may indicate that incomplete milk-out occurred. If it is assumed that all cows were milked out to the same degree, rankings for milk fat percentage would not be affected, even though absolute values were underestimated. Milk protein and lactose percentages would not be expected to be affected by degree of milk-out. Small-rotation cows were lower for both these constituents than were cows of other systems. Largerotation cows consumed the greatest amount of energy during the dry, lactation, and annual periods, whereas Hereford consumed the least amount of energy (Table 4). Small rotation and Angus-large rotation cows were intermediate in consumption. These results agree with NRC (1984) requirements, providing heavier cattle or cattle that produce higher amounts of milk with more feed than lighter cattle or cattle that produce lower amounts of milk. The actual values were 80% (Hereford) and 9 0% (other breeding systems) of the level given by NRC (1984). The breeding
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*HH Hereford, SR = small rotation, LR = large rotation, AL Angus-large rotation, AN Pinzgauer, TA = Tarentaise, CH = Charolais, MA Maine Anjou, and SM Simmental, bDeleted from analysis.
3690
FISS AND WILTON
Table 3. Classification variables and covariates included in the final reduced models for traits of heifers and cows Modela
(in addition to BS, and SI and random effects) Classificationb
CovariateC
Weight of cow at weaning Condition of cow at weaning Average daily milk yield Milk composition Fat Lactose Protein Feed intake Dry period Lactation period Annual Reproduction of heifers First-service pregnancy rate Days to pregnancyd Age at first calvingd Reproduction of mature cows First-service pregnancy rate Pregnancy rate Days to pregnancy
AC, AD, RA, YR, SI*YR RA, YR, CT, SI*YR AC, AD, RA, YR, CT. SS, SI+CT, SI*YR, SI*SS
MY, WA, CO CW, MY CW. WA
RA, YR YR, SI*YR RA, YR, SI'YR
CW, MY, CO CW, MY
RA, YR, SI*YR AC, RA, YR, CT, BC, SI'AC, SI*CT, SI*YR RA, YR, SI*YR
CW, MY, DD CW, MY, WA, CO. CC, CC2 CW, MY, CO
AD, YR YR, SF, SI+BC YR, MG
CW, MY CW, MY, CO, JB, JB2 CW, MY, CO, C02, JB
AC, AD, SB AC, AD, SS, SB, SI*AC YR, SB
CW, MY CW, MY, CO CW, MY
CW, MY
'BS = breeding system, SI = breed of sire of cow. AC = age of cow, AD = age of dam of cow or heifer, RA = ration, YR = year, CT = calf trial, SS = sex of suckling calf, BC = maternal grandsire breed, SB service sire breed, quadratic effects are sex of fetus, MG breed of sire of suckling calf, SF denoted by superscript, and *. cCW cow weight, WA age of calf at weaning, CO = cow condition, MY = milk yield, DD = dry days, CC = change in cow condition from birth to weaning, and JB = female's julian birthdate. dQuadratic effect of weight was also included.
-
-
-
-
system rankings agree with the data of McMorris and Wilton (1986) and Armstrong et al. (19901, who analyzed a subset of the data in this study. Other than age at first calving, breeding systems were similar in reproductive performance of heifers and cows (Table 4). This agrees with the findings of Steffan et al. (19851 for Hereford heifer pregnancy rate and services per pregnancy when compared to crossbreds. Other researchers found no differences for first-service pregnancy rate, pregnancy rate (Cundiff, 1970; Bailey and Moore, 1980; Nelson and Beavers, 1982; Cundiff et al., 1986; Fredeen et al., 1988; Fiss and Wilton, 19891, and traits related to days to pregnancy of cows [Azzam and Nielsen, 1987; Fredeen et al., 1988; Fiss and Wilton, 19891. Age a t first calving of Hereford heifers was significantly higher than that of smalland large-rotation heifers. Although Fiss and Wilton (1989) found no significant differences between breeding systems for age at fiist calving on a subset of the data, the same trend was observed. Differences between these two studies may be due to additional data and inclusion in the present study of covariates for heifer milk yield, weight, and julian birth date. Average age of calving was close to or less than 2 yr in all cases. Under the conditions of this research, which
-
included feeding to requirements, there seemed to be little difference in reproductive performance among breeding systems.
Small Rotation Means There were few significant differences in least squares means among small-rotation breeds (Gelbvieh-, Pinzgauer-, and Tarentaise-sired cows) (Table 5). However, Tarentaise-sired cows tended to have lower weights and milk yields than did Gelbvieh- and Pinzgauer-sired cows. Cundiff et al. (19861, however, found Pinzgauer- and Tarentaise sired cows from Angus and Hereford dams similar to each other in weight and milk yield. The Gelbvieh-sired cows from Angus and Hereford dams that Cundiff et al. (1986) studied were 30 kg heavier with milk yields similar to Pinzgauer and Tarentaise. Small-rotationbreeds did not differ significantly in their milk fat percentage. However, Gelbviehsired cows had lower milk lactose and protein percentages than did Pinzgauer- and Tarentaisesired cows (P < .051 (Table 5). The milk lactose and protein percentages of Gelbvieh-sired cows were below the lactose and protein percentages found by Mondragon et al. (19831 for beef, dairy x beef,
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Trait
3691
EFFECTS ON TRAITS OF BEEF COWS
Table 4. Breeding system least squares means (LSM) and standard errors (SEI for traits of heifers and cows
Trait
548' 9.37b 4.17' 3.31b 5.2Qb 3.41bC 2.375' 3,342' 5,727'
SE
LSM
8
.50 .31
561' 7.09' 7.74b
.13 .05 .06 44 317 63
SE 15 .70 .58
67Eb 3.21d 8.85b
.l6 .13 .I1
2.45' 4.94c 3.54b
2.58' 4.38' 3.25' 2,702' 4,016' 7,052'
LSM
3,020b 4,804b 7,748b
106 29 1 149
66.7 4.87 735b
12.9 .33 3
65.8 5.73 715'
9.5
45.6 85.5 5.77
7.8 8.8 .6 1
59.9 78.6 5.81
9.7 8.8 .99
BO 8
54.9 5.48 717' 73.2 82.0 6.49
SE
LSM
11
.56 .40 .17 .09 .08
69 157 107
586' 7.31' 7.18b
2.8EbC 4.99b' 3.61bC 2,954bc 3,817' 7,235'
SE 20
.e2 31 .23 .20 .17 121 393 176
.81
62.3 4.34 724bC
14.1 .86 9
9.7 8.9 .85
68.9 91.0 7.29
14.7 14.0 1.44
12.4
6
&H = Hereford, SR = small rotation, LR = large rotation, and AL = Angus-large rotation (cows with Angus sires, large rotation dams). b,c-dMeans in same row with no common superscripts differ Ip e .051.
and dairy cattle and the protein percentage of Holsteins found by Ng-Kwai-Hang et al. (1984) and Monardes and Hayes (1985). This difference for Gelbvieh-sired cows is difficult to explain, no outlier values were found. Gelbvieh- and Pinzgauer-sired cows had similar feed intakes during the dry period, both were lower than Tarentaise-sired cows (Table 51. During the lactation period and annually, the smallrotation breeds were similar in feed intakes, although Gelbvieh-sired cows tended to consume more energy than the other small-rotation breeds during lactation and less energy annually. Annual feed intake was not the sum of dry and lactation periods because of the exclusion of first-parity records from both dry and annual intake analyses. Laster et al. (19791 and Gregory et al. (19791 found Gelbvieh, Pinzgauer, and Tarentaise to have different ages a t puberty but similar pregnancy rates in heifers. Cundiff et al. (19861 reported pregnancy rates of cows to be similar for these three breeds. In the present study, no significant differences were found in the reproductive performance of the small rotation breeds (Table 5). However, Gelbvieh-sired heifers tended to have better reproductive performance with higher firstservice pregnancy rate and lower days to preg nancy and age at first calving. Gelbvieh-sired cows tended to have poorer reproductive performance with lower first service and overall pregnancy rates and higher days to pregnancy. Over all reproductive traits studied, Pinzgauer tended to have the best reproductive performance of the
small-rotation breeds, except for days to preg nancy in heifers and age a t first calving. Trends for days to pregnancy and age a t first calving should be similar because days to pregnancy measures length of time from start of breeding season to conception.
Large Ro tu tion Means The large-rotation breeds (Charolais-, Maine Anjou-, and Simmental-sired cows) had similar weights, milk yields, and conditions a t weaning (Table 6). Charolais and Simmental have been found to be similar in weight by Cundiff et al. (19861. In two studies that included Maine Anjou and either Charolais or Simmental (Cundiff et al., 1986; Petit and Lienard, 19881, Maine Anjou was also found similar in weight to Charolais and Simmental. Generally, Charolais have been found to produce less milk than Simmental (Notter et al., 1978; Bowden, 1980; Cundiff et al., 1986). However, Jenkins and Ferrell (19841 found no significant differences between milk yield of Charolais- and Simmental-sired cows as in this study. Fredeen et al. (19881 found milk production of Charolais and Simmental depended on the environment. Charolais produced less than Simmental on pasture and equivalent to Simmental under intensive management. Possible reactions for Charolais producing the same amount of milk as Simmental in this study may be persistency differences depending on feed availability, genetic change, or sample differences. There were no detectable
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Cow wt a t weaning, kg Cow condition a t weaning, mm Milk yield, kg/d Milk composition, % Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, k Days to pregnancy, dd Age a t first calving, d cows First-service pregnancy rate, % Pregnancy rate, % Days to pregnancy, dd
LSM
AL
LR
SR
HHa
3692
FISS AND WILTON
Table 5. Least squares means (LSM)and standard errors (SE) for characteristics of heifers and cows of the small rotation breeds Sire breed of cow PZ
GVa
Trait
SE
LSM
57 1 6.29 8.36
21 1.16 .98
2.58 2.92' 2.40'
.24 .21 .17
2,553' 4,168 6,818
150 430 274
572 7.00 8.23
SE 23 1.17 1.01
2.61 5.14b 3.66b 2,574bC 3,855 7,146
LSM
.27 .19 .17 220 392 274
540 7.98 6.64 2.55 5.10b 3.6eb 2,980b 4,025 7,193
SE 27 .94 .99 .25 .27 .22 155 573 287
69.9 5.60 702
14.7 .70 10
67.4 6.32 728
14.4 1.04 13
60.1 5.25 714
15.5 1.09 9
50.6 69.3 7.24
13.5 13.3 1.37
73.1 84.1 4.59
13.4 12.0 1.41
56.0 82.5 5.50
15.0 14.3 1.35
&GV = Gelbvieh-sired, PZ = Pinzgauer-sired. and TA = Tarentaise-sired. bscMeans in same row with no common superscripts differ (P c .05).
differences in milk component percentages among breeds (Table 61, although a n insignificant difference in milk fat percentage of . 5 % between Maine Anjou- and Simmental-sired cows was estimated. Bowden (1980) and Fredeen et al. (19881 also found no differences in milk fat percentage between Charolais and Simmental. Bowden (19801 found that Charolais had a higher protein percentage than did Hereford and Angus cows when milked 14 wk into lactation but not at 6 or 12 wk into lactation. Fredeen et al. (1988) found no differences in milk protein percentages averaged over the lactation. There were no differences detected in intakes during the lactation period for Charolais-, Maine Anjou-, and Simmental-sired cows or between Charolais- and. Simmental-sired cows during the dry period or annually. In this study, Maine Anjousired cows had significantly lower feed consumption than Charolais-sired cows in the dry period, and Charolais- and Simmental-sired cows annually, even though Maine Anjou-sired cows were not significantly different from Charolais- and Simmental-sired cows in either weight or milk production (Table 8). According to NRC (19841, feed intake of cattle is dependent on weight and milk yield, suggesting all large-rotation breeds should have consumed a n equal amount of feed during all periods. Possible reasons for the reduction in feed intake of the Maine Anjou-sired cows are that
their temperament may be better suited for confinement housing, the Maine Anjou-sired cows may be more efficient than Charolais- and Simmental-sired cows, or the sample of cattle chosen. Warwick and Cobb (19751, in a review, also indicated that there is genetic variation between breeds in voluntary feed intake. Fredeen et al. (1987)also found no differences between dry period intake for Charolais and Simmental cows, and Bowden (1980) found no difference in lactation period intake for Charolais and Simmental cows. Charolais-sired heifers had significantly lower first-service pregnancy rates of heifers than the other large-rotation breeds with no other significant differences among Charolais-, Maine Anjou-, and Simmental-sired heifers and cows for reproductive traits (Table 6). Maine Anjou-sired heifers and cows tended to have the best reproductive performance with higher heifer and cow firstservice pregnancy rate, higher cow pregnancy rate, lower heifer and cow days to pregnancy, and lower age at first calving. Cundiff et al. (1986) also reported that Maine Anjou had a slightly higher pregnancy rate than Charolais and Simmental. Laster et al. (1976) found Charolais and Simmental to have heifer calving rates similar to Hereford and Angus, and Maine Anjou to have a higher heifer pregnancy rate than Hereford and Angus, although not significantly so.
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Weight of cow a t weaning, kg Condition of cow a t weaning, mm Milk yield, kg/d Milk composition, YO Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, YO Days to pregnancy, dd Age at first calving, d cows First-service pregnancy, % Pregnancy rate, % Days to pregnancy, dd
LSM
TA
EFFECTS ON
TRAITS OF BEEF COWS
3693
Table 6 . Least squares means (LSM) and standard errors (SE) for characteristics of heifers and cows of the large rotation breeds Site breed of cow CHa Trait
LSM
SM
MA
SE
LSM
SE
LSM
SE
~
cows First-service pregnancy rate, YO Pregnancy rate, Or6 Days to pregnancy, dd
684 3.63 9.04 2.35 4.91 3.49 3,24Eb 4,606
8,100b
19 .66
686 3.07 8.85
.22 .15 .13
2.23 5.00 3.81
.81
111 267 164
31.8' 7.01 715
14.9 1.24
76.8 80.7 8.85
13.6 12.8 1.09
8
2,772' 4,083 7,364'
15
.81 .57 .22 .13 .ll 105 196 168
664 2.92 8.05
18 .77 .56
2.76 4.92 3.51
.27
3,03QbC 4,923 7,781'
.10
.oo 85 102 132
69.4b 4.34 710
15.6 1.03 13
63.5b 5.08 727
14.1 .65 8
77.6 94.2 5.51
12.3 11.8 1.21
65.3 71.0 7.11
10.2 9.9 .82
&CH = Charolaissired, MA = Maine Anjou-sired, and SM = Simmental-sired. bicMeans in same row with no common superscripts differ (P < .05).
Cow Weight Generally, increasing cow weights were associated with increases in cow condition, milk yield, and feed intake within the Hereford, smallrotation, or large-rotation breeding systems lTable 71. The positive partial regression coefficient for condition on cow weight at weaning is contrary to the results for breeding systems in which largerotation cattle (heavy weights) were thinner than the other breeding systems (lighter weights). Onks et al. (19751,Marshall et al. (19781, Anderson et al. (19831,and McMorris and Wilton (1986)all found a positive association between cow weight and feed intakes across breeds both with and without breed accounted for by the model, whereas significant associations were found only for the lactation and annual periods for Hereford in the present study. The lack of a significant association between cow weight and reproductive tracts (Table 7) was also found by Fiss and Wilton (1989). However, cow first-service and overall pregnancy rate did tend to decrease with increasing weight of cow in all breeding systems. Associations between weight of cow and other traits were of similar magnitude in each of the crossbred breeding systems. However, Hereford cows usually had associations between weight and other traits that were different from crossbreds. For milk yield, the association with cow weight
was negative and significantly different from the other breeding systems. This difference between Hereford and the other breeding systems may be a breed effect, due to the physical capacity of the animals, or due to the greater condition of the heavier Hereford cows. Milk composition increased with increases in cow weight for Hereford (Table 7) but not other breeding systems. However, the changes for Hereford were small and may reflect a decrease in milk yield with a concomitant increase in milk constituents. Breeding systems did not differ for associations between cow weight and feed intake or reproductive performance. However, Hereford was the only breeding system with significant increases in lactation and annual feed intake.
Milk Yield No association between milk yield and condition was detected across breeding systems (Table 8). The lack of association between condition and milk yield was expected because cows were fed to production requirements. For cow weight and milk yield, breeding systems followed the same trends in association as reported in the cow weight section, negative coefficients for Hereford, and positive or insignificant for the other breeding systems. No significant associations between milk yield and feed intake, other than annual intakes
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Weight of cow at weaning, kg Condition of cow at weaning, mm Milk yield, kg/d Milk composition, % Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, VO Days to pregnancy, dd Age at first calving, d
3694
FISS AND WILTON
Table 7. Breeding system partial regression coefficients (b) and standard errors (SE) for characteristics of heifers and cows on weight of cow at weaninga H H ~ Trait
LR
b
SE
b
SE
b
,204'' -.O 15'*d
.029 .020
.140' .07 1
.059 .040
.105** .074*'
.045 .031
.025
.010 ,000 .005
.018 .012 .010
.004 .009
.015 .011 .009
,008
.009 -1.4 12.0'' 12.4.
4.0 4.5
0.0
.05
1.22
-.008
.004 .014 20.1 -18.5 -44.7
48.5 14.4 28.1 1.20
-1.10
SE
-.006 4.4 14.7 27.8
9.5 10.1 14.8
1.07
-1.06
,037 ,000
.139* .002
.OB1 ,001
.030 -.002'
,080
-.ooo 1.05" -.004
.37 .004
-.07 .045**
.70 ,010
.81 -.002
.82 .o 11
-32 -.57 -.029
.53 .52 .034
1.19 1.11 .113
-.48 -.09
.75 39
.04 1
-1.04 -.8 1 -.037
-
-
&per 10 kg. small rotation, and LR large rotation. bHH = Hereford rotation, SR c.dPartial regression coefficients in same row with no common superscript differ [P *H,:b = 0, P < .05. **P < .01.
.001
.075
.088
,051.
Table 8. Breeding system partial regression coefficients (b) and standard errors (SE) for characteristics of heifers and cows on milk yielda H H ~ Trait
b ~~
~~~~~
Weight of cow at weaning, kg Condition of cow at weaning, mm Milk composition, oh Fat Lactose Protein Feed intake, Mcal of ME Dry period Lactation period Annual Heifers First-service pregnancy rate, 96 Days to pregnancy, dd Age at first calving, d cows First-service pregnancy rate, 010 Pregnancy rate, O/O Days to pregnancy, dd
~~~
SR SE
LR
b
SE
-4.24*d -.203
1.05 ,104
-3.0Ed .I20
3.79 .190
,158.' ,000 -.025
,035 .02 1 ,017
.020 .007
.050 .039 ,031
20.3 17.9 38.2
12.9 14.2 19.4
-.068*
-18.5 10.1 141.P
138.9 44.7 02.2
.01.
SE
7.34 **c -.059
2.50 .147
,082 -.014 -.019 -5.1 25.4 24.3
.050 .039 .030 28.9 29.2 42.5
-4.70 ,320" 4.17**cd
4.18 .lo9 1.09
-2.52 .317 7.82**'
4.02 ,290 2.70
-4.92 -.040 1.12Cd
3.94 2.13 2.83
-1.08
1.82 1.55 ,025
0.4 1 1.63 -.095
3.72 3.40 ,311
-1.55 2.43 -.022
2.79 2.40 .I38
-.E9 ,039
"per 1 kg/d. bHH = Hereford, SR = small rotation, and LR = large rotation. 'VdPartial regression coefficients in same row with no common superscript differ (P < .05). 'H,:b = 0, P < .05.
**P
