Effects of Isolation of Calves on Growth, Behavior, and First Lactation Milk Yield of Holstein Cows1 C. W. ARAVE
Animal, Dairy and Veterinary SCiences Department Utah State University
Logan 84322-4815
J. L. ALBRIGHT Animal Science Department Purdue University West Lafayette, IN 47906 D. V. ARMSTRONG Department of Animal Science University of Arizona Tucson 85721
W. W. FOSTER Department of Dairy Science South Dakota State University Brookings 57007 L. L. LARSON Department of Animal Science University of Nebraska Lincoln 68583-0908 ABSTRACT
triplet calves were obtained by transferring split embryos into recipients, one member of each pair was reared in a group, and the twin was reared in isolation. Early rearing previously had been found to affect growth, feed intake, dominance rank, and learning ability of calves, and, in our study, the subsequent milk yield of calves reared in isolation tended to average more than for calves in groups. Intraclass correlations between monozygous twin pairs for milk, fat, relative value milk, and relative value fat were lower than anticipated. These data indicate that preweaning isolation did not affect ftrst lactation milk yield traits. (Key words: calf rearing, behavior, ftrst lactation yield)
=
Holstein (n 323) calves in the herds of four experiment stations were reared individually (control) or ip isolation to 70 d of age to detennine whether isolation affected growth, behavior, and ftrst lactation yield. Treatment differences were not observed for average daily gain for BW at d 28, 56, or 70. Postweaning approach distance was measured in two herds (n = 122; n = 28). Detailed preand postweaning behaviors were reported in one herd (n 26). Isolation did not affect subsequent milk yield or culling percentages. In a second experiment, seven pairs of monozygous twins and a set of identical
=
Received April 13, 1992. Accepted July 10, 1992. 'Data are from the NC-1l9 Regional Research Project, Dairy Herd Management Strategies for Improved Decision Making and Profitability. This research was partially supported in the Utah Agricultura1 Experiment Station, Utah State University, Logan 84322-4810, approved as Journal Paper Nurnber 4308. Purdue Agricultura1 Experiment Station, approved as Journal Paper Number 13312. 1992 J Dairy Sci 75:3408-3415
Abbreviation key: ME MZ monozygous.
=
= mature
equivalent,
INTRODUCTION
Early rearing experience affects adult behavior in several species (1). Calves reared in
3408
3409
ISOLAnON EFFECTS ON GROWTH, BEHAVIOR, AND YIELD TABLE 1. Average daily gain from birth to weaning of calves reared individually or in isolation. Herd
Treatment
Number
Birth weight
28 d
56 d
70 d
(kg) Control Isolation 2 3 4
Control Isolation Control Isolation Control Isolation
29 29 59 63
43 40 40 40
.31 .29 .36 .38
.46 .46
.50 .50 .57 .55
13 13
44
.32 .30
.50 .47 .70 .69
.64
40
59 58
isolation are less dominant than calves reared in groups (1, 5, 10). However, results of a study involving monozygous (MZ) twin heifers indicated that a strong genetic component is associated with social dominance (7). Isolation also affected other behaviors, such as time spent eating and ability to traverse a T maze. The first lactation milk yield of Holstein calves reared in isolation exceeded that of their contemporaries reared in groups (1, 2, 6, 10). Rearing calves in isolation was associated with a significant reduction in SCC but did not affect health, reproductive parameters, or milk yield (8). One hypothesis attributed higher milk yield by isolated calves to their more docile nature and socialization to humans during early rearing experience (2), but additional research was recommended concerning the influence of early experience on adult function. The two experiments reported herein were initiated to study further the effects of isolation and group rearing in individual hutches described by Arave et al. (1) and to use MZ twins to remove genetic bias from performance comparisons. MATERIALS AND METHODS
This cooperative study involved researchers at five experiment stations. Four stations (Table 1) followed the same preweaning protocol, in which isolated calves (n = 163) were reared in hutches or pens that were surrounded with plywood (1.2 m high) to create a visual barrier. Calves could see open sky and could physically interact with their human caretaker but not with other calves. TIle pens and hutches
.51 .53
44
42
.68 .76 .74
used for unisolated calves (n = 160) were similar but lacked a visual barrier. Calves were removed from their dams as soon as practicable after birth, moved to individual pens, and hand-fed their first colostrum. Calves were assigned randomly to treatments, but a balance was maintained based on sire's PD and dam's cow index. Each station followed its normal feeding regimen for both treatments. Calves were weaned at approximately 10 wk of age. Approach distance was measured at weaning in herds 2 (n 122) and 3 (n 26). When a calf was put in an enclosed pen, the approach distance was how close that calf would come to a person kneeling in the pen. Approach distance was determined at 5 and 10 min. Weaned calves were returned to the standard herd management practices. Birth weight; BW at 4, 8, and 10 wk; breeding and calving age; postpartum BW; first lactation yield; sire PD; dam cow index; and social behavior were determined, although complete data were not available from all stations. Data from 243 calves (cows when data were obtained, n = 48, 89, 18, and 88 from herds 1, 2, 3, and 4, respectively) were analyzed. At the Utah station, MZ twins were obtained by transferring split embryos into recipients (n = 181). One MZ twin was assigned randomly to be reared in isolation, and the other was reared in a group of five or six calves. Embryos were transferred at Ruann Dairy, a large commercial dairy near Fresno, CA. Seven pairs of MZ twin heifers and one set of identical triplets resulted from the embryo transfer. Two of the triplet calves were reared in isolation. Before calves were weaned,
=
=
Journal of Dairy Science Vol. 75, No. 12. 1992
3410
ARAVE ET AL.
TABLE 2. Effect of rearing calves in isolation on approach distances postweaning (n = 122). Time observed 1 Week
Day
Treatment
5 min
I I 2
Isolation Isolation Control Control
3.96 5.18 4.88 4.27
4.88 5.49 5.79 5.18
I 2 I 2
Isolation Isolation Control Control
5.18 5.49 6.10 6.10
5.49 6.10 5.79 6.40
10 min (m)
2
2
1Time
after first introduction to an observer.
they were reared separately from other calves on the farm, but the feeding, vaccination schedules, and management practices were otherwise similar to those used at the dairy. Calves in isolation were reared in polyvinyl dome hutches separated by 1.2 x 2.4-m plywood panels. A group pen consisted of three standard wooden hutches placed side by side that faced three similarly arranged hutches located across 1.5 m of space. Space between rows of hutches was enclosed by a locking manger on one side and a panel on the other. The ends of the hutches were removed to allow access by all calves. Behavior was evaluated when calves were 4 to 6 wk old (7). At weaning, calves were put through a T maze five times on 3 consecutive d. They were then reared in groups containing 80 calves.
(ME) milk, and ME fat were the dependent variables. In the study involving six pairs of MZ twins, ME milk, fat, and FCM and relative value milk, fat, and FCM were the dependent variables. The general linear models procedure of SAS (9) was used in data analyses. RESULTS AND DISCUSSION Experiment 1
At one station, the difference in average daily gain of 13 calves reared in isolation
2.7m
Statistical Analysis
Data on behavioral observations were analyzed by least squares ANOVA techniques under a completely randomized design with treatment (isolation vs. individual) as the main effect. Analyses were conducted separately for group 1 and group 2 data and for the two groups pooled in one data set. Data from the four experiment station herds were pooled to analyze the effects of rearing on subsequent milk yield. Treatment, herd, and treatment by herd interaction effects were included in the model along with birth weight, age at calving, sire's PD milk and fat, and dam's cow index milk and fat as covariates. Records missing any covariate value were not used in the analysis. Fat-corrected milk, mature equivalent Journal of Dairy Science Vol. 75, No. 12, 1992
.
Corri dar 13.7 m
Door
.
Feed room 2 .7m
7m Figure l. Approach score testing area for calves postweaned from rearing in isolation or individual hutches (n = 26).
3411
ISOLATION EFFECI'S ON GROWTH, BEHAVIOR, AND YIELD TABLE 3. Effect of isolation rearing on approach distance = 26).
(n
Conditions
Group II
Group 22 (m)
Treatment Isolation Control
2.62 3.23
2.96 2.68
Observer location Feed room Corridor
2.383.51 b
2.383.26b
Observer type Familiar male Unfamiliar male Familiar female Unfamiliar female
3.08b 4.33b 2.132.19-
3.54b 3.35 b .941 3.44b
Test time 5 min 10 min
3.02 2.83
2.77 2.87
=
and herd 3 (n 26). In wk 1, isolated calves tended to let observers approach more closely than did calves reared in groups, but the difference was not significant (Table 2). A second approach experiment (herd 3, n 26) was conducted in a modified testing arena (Figure I). The only significant (P < .05) differences occurred when calves were all allowed to circle the observer. Under these conditions, some significant (P < .0I) differences in approach scores (Table 3) occurred that did not involve the effects of isolation but, instead, involved the familiarity of a calf with the observer and the gender of the observer (Table 3). Calves in herd 3 were continuously observed for 24 h to determine the time spent in 14 behaviors and activities and calf position in the stalls (Table 4). Calves reared in isolation spent significantly (P < .01) less time at the back of stalls and more time (P < .02) at the side of stalls, reflecting differences in behavioral thermoregulation. Calves in group I were raised during the winter, and calves in the control group had less protection from the elements than did calves reared in isolation, which may explain why calves in the control group spent more time in the most protected location at the rear of the stall. Standing time may be the behavior that is most indicative of stress. In group 2, calves reared in isolation spent significantly (P < .02) more time standing than did control calves. At our station (herd 3) we recorded the time that calves socialized with other calves (most
=
a.bMeans in columns in same group within condition with different superscripts differ: observer lotation (P < .05), observer type (P < .01). IFall to winter 1984. 2Spring to sununer 1985.
versus 13 calves reared individually from 8 to 10 wk preweaning was significant (P < .05). However, overall change in preweaning BW, a traditional measure of animal well-being, was not affected by isolation (Table I). Approach distances were measured I and 2 wk postweaning (after calves had been housed in a group) at two stations: herd 2 (n 122)
=
TABLE 4. Behavioral and general activity and stall orientation by heifer calves during 24-h d (n
Group 22
Group 11 Control
= 26).
Isolation
Control
Isolation
(%)
Activity Standing Lying head up Lying head down Stall orientation Front Back Side
19 50 31
30 44 26
2755 19
45b 47 8
42 57l
59 24b 18b
43 40 17
45 47 8
Il
a.bMeans in rows in the same group with different superscripts differ: standing (P < .02), back (P < .01), side (P < .02). 'Fall to winter 1984. 2Spring to sununer 1985. Journal of Dairy Science Vol. 75, No. 12, 1992
3412
ARAVE ET AL.
TABLE 5. Maintenance behavior of calves reared individually or in isolation preweaning (n
Group 22
Group 11 Activity
Control
= 26).
Isolation
Control
Isolation
(min) Eating Drinking Eliminating Ruminating Investigating Socializing Playing Grooming
56 5 2 217 98 121 32
34
61
5 1 221 201 4b 0 32
34
120 50 2 352 253 4 4 50
1 377 123
11 1 55
-.bMeans in rows within groups with different superscripts differ (P < .05). IFalI to winter 1984. 2S pring to sununer 1985.
commonly by nuzzling and licking each other's heads and faces) and with humans (Table 5). Isolated calves socialized significantly (P < .05) less than control calves. Vocalizations (herd 3) for individual calves were extremely variable and are probably not a reliable indicator of stress (Table 6). Isolation did not significantly affect the number of times that calves vocalized, which was consistent with the results of similar studies (1, 10) in which calves reared in isolation and in individual pens were monitored at weaning. Creel and Albright (3, 4) hypothesized that calfhood isolation may subliminally stimulate the adrenal cortical complex and thereby enhance responsiveness to acute stress as adults.
When they (3, 4) measured urinary cortisol concentrations at biweekly intervals preweaning and blood serum cortisol immediately after calves were exposed to an acute stress, the difference in cortisol concentrations in urine was not significant, but the difference in the serum cortisol concentrations of isolated (13.2 nglml) and control (9.4 nglml) calves (4) was significant (P < .01). The difference in the incidence of illness between the two groups of calves was not significant, which indicates that rearing in isolation did not suppress the immune system. Health records from the other stations involved in the study also failed to show a difference in the health of the two groups of calves.
TABLE 6. Vocalization, expressed as number of occurrences in a 2-h period (n = 26). Group 22
Group 11 Control Heifer I
2 3
13 13
o
4
o
5 6
4 64
Isolation
2
o o
Heifer 7
8
15.5 24
SE IFall to winter 1984. 2Spring to sununer 1985.
Journal of Dairy Science Vol. 75. No. 12, 1992
Isolation
o 1 o
51
1
9 10
4
131 6
11
2
12
3
13
X
Control
23.3 53
8 8
o
o 14 o o
1.4 2
11.6 18
3413
ISOLATION EFFECTS ON GROWTH, BEHAVIOR, AND YIELD
TABLE 7. Least squares means for measures of milk yield of heifers reared individually or in isolation (243 cows in four experiment station herds). Yield characteristic 1 Treatment
FCM
SE
MEM
Control Isolation
8782 8852
156 137
8776 8841
SE
MEF
SE
176 154
308 310
5 5
(kg)
lMEM
= Mature equivalent milk; MEF = mature equivalent fat.
Milk yields of cows reared in isolation averaged more than those of control cows (+70 kg of FCM, +65 kg of ME milk, and +2 kg of ME fat), but none of the differences was significant (Table 7). The difference in mean FCM, ME milk, and ME fat between the groups was less than 1%. The type of rearing regimen did not significantly affect yield traits (Table 8). Several factors influenced milk yield, but findings did not support the results of another study (1) in which FCM yield of isolates was substantially greater than that of cows reared in groups or individually without isolation. The difference in FCM was less between cows reared individually and isolated cows than between cows reared in groups and isolated cows (1).
The results of this type of experiment could be biased if a greater proportion of low yielding cows in one group were culled before completion of their first lactations, which prob-
ably did not occur in this study. Less than 10% of the cows in this study (263 of the original 323 calves had fIrst lactations; 95 culled cows included 5 with second lactations) were culled for low yield, and the number of cows culled because of treatment for reproductive or health problems was nearly equal in both groups (Table 9). Experiment 2
The effects of early rearing on growth, feed intake, social development, survival, and learning ability were reported earlier (7). Briefly, no significant differences existed in average daily gain or in feed intake between isolated and control calves, although calves reared in groups spent significantly (P < .05) more of a 24-h d eating than did isolated calves (10.9 vs. 5.4%). Social facilitation appears to influence calves reared in groups, as was also evident in
TABLE 8. Probability values and significance of sources of variation in parameters related to fust lactation milk yield of heifers (n 242) reared in isolation and in standard hutches.
=
Dependent variables 1 Source 1
df
FCM
MEM
MEF
Treatment Herd (H) TxH Birth weight Age PDM PDF CIM CIF
1 3 3 1 1 1 1 1 1
.11 10.59** .95 .03 .07 6.04* .90 6.40* .22
.08 19.08** .75
.12 6.72** .98
=
=
(n
lMEM Mature equivalent milk; MEF mature equivalent fat; PDM dam's cow index milk; ClF = dam's cow index fat.
.13 .24 18.99** .57 21.16** 3.51
0 0 .33 5.08* .25 5.56*
=sire's PO milk; PDF =sire's PO fat; CIM =
*p < .05. **p < .01. Journal of Dairy Science Vol. 75, No. 12, 1992
3414
ARAVE ET AL.
TABLE 9. Reasons for disposal of cows reared individually or isolated (data from 263 cows in four herds; 5 of 95 culled cows had two lactations at time of analysis). Reason
Individual (n)
Low yield 15 Reproductive failure 15 Health 9 Other 9 Unknown 5 Mean age at disposal. mo
Isolation
(%)1
(n)
(%)1
28 28 17 17 9
9 11 7 10 5
21 26 17 24 12
39.38
38.32
1Percentage of all cows culled.
another study (10). The time spent resting or the side on which calves rested (laterality) did not differ by treatment. Social behavior was assessed when heifers were 15 to 17 mo of age, and no relationship was found between dominance rank and either age or BW, but the intraclass correlation (r = .93) between twin pairs for dominance indicated that dominance was associated with genotype. During the ftrst 2 d of a 3-d postweaning trial, isolated calves reached the goal in a T maze signiftcantly (P < .05) sooner than calves reared in groups. We tried to determine approach distance when calves were between 5 and 7 mo of age, but, regardless of treatment, calves were too wary of an observer to allow this trait to be measured accurately. The "enhanced humananimal bond" (7) seemed to have been extinguished in these heifers, perhaps because of the relatively large groups (approximately 80 calves) in which calves were reared after they were weaned at 70 d. The MZ twin cows that were reared in isolation had greater yield (+221 kg of milk, +7 kg of fat, and +200 kg of FCM) than the twins reared in groups, but the differences were not significant (Table 10). Largest differ-
ences occurred for relative value milk (deviation of a cow from the base ME, which is calculated each test day by averaging the ME yield of each cow on the barn sheet) (515 kg), and for relative value FCM (77 kg). Relative value provides a more accurate evaluation of a cow's performance than her lactation average because it compares milk yield with that of herdmates that calved in the same season and that receive the same feeding and management regimens. The low intraclass correlations between MZ twin pairs for yield traits (milk, r' = .34; fat, r' = -.36; relative value milk, r' = .34; relative value fat, r' = .26) were anomalous because differences between MZ twins should largely reflect environmental factors. CONCLUSIONS
Before calves were weaned, they were reared in either isolation or individual housing to determine whether isolation affected growth, behavior, or yield characteristics. Rearing in isolation had some effects on where calves stood in their stall and on socialization but did not affect health or yield characteristics. Similarly, no differences existed in the yields of MZ twin pairs, one of which had been reared in isolation and one of which had been reared in a group, although treatment-related differences existed in the time that calves spent eating and in their performance in a T maze. The yield differences between MZ twins were far greater than expected. Rearing in isolation had minimal, shortterm effects on preweaning behavior. Yield characteristics were not enhanced by rearing in isolation, unlike the findings of previous studies (1, 2, 6, 10) that involved fewer calves. The results also show the utility of using MZ twins in management studies.
TABLE 10. Milk yield comparisons of monozygous twin cows reared in a group or in isolation preweaning.
Mature equivalent Treatment
n
Milk
Fat
Relative value
FCM
Milk
Fat
FCM
543 1058
10 14
401 478
(kg) Group Isolation
6 6
12.324 12.545
Journal of Dairy Science Vol. 75. No. 12. 1992
423 430
11,277 11,477
ISOLAnON EFFECTS ON GROWTH, BEHAVIOR, AND YIELD
REFERENCES I Arave, C. W., C. H. Mickelsen, and 1. L. Walters. 1985. Effect of early rearing experience on subsequent behavior and production of Holstein heifers. J. Dairy Sci. 68:923. 2 Arave, C. W., and V. D. Warnick. 1979. Heifers raised in isolation milked well at Utah State. Hoard's Dairyman 124(4):618. 3 Creel, S. R., and J. L. Albright. 1987. Early experience. Page 251 in Farm Animal Behavior. The Veterinary Clinics of North America: Food Animal Practice. Vol. 3. E. O. Price, ed. W. B. Saunders Co., Philadelphia, PA. 4 Creel, S. R., and J. L. Albright. 1988. The effects of neonatal social isolation on the behavior and endocrine function of Holstein calves. Appl. Anim. Behav. Sci. 21 :293. 5 Donaldson, S. L. 1967. The effect of early feeding and rearing experiences on the dominance, aggression, and
3415
submission behavior of young heifer calves. M.S. Thesis, Purdue Univ., West Lafayette, IN. 6 Donaldson, S. L., J. L. Albright, and W. C. Black. 1972. Primary social relationships and cattle behavior. Proc. Indiana Acad. Sci. 81:345. 7 Purcell. D., and C. W. Arave. 1991. Isolation vs. group rearing in monozygous twin heifer calves. Appl. Anim. Behav. Sci. 31:147. 8 Rakes, A. H. 1988. The effect of raising heifers in isolation during the first ten weeks on their growth and performance. J. Dairy Sci. 71(Suppl. 1): 283.(Abstr.) 9 VAXlYMS Operating System. 1986. Production Release 5.16. SAS Inst. Inc., Cary, NC. 10 Warnick, V. D., C. W. Arave, and C. H. Mickelsen. 1977. Effects of group, individual, and isolated rearing of calves on weight gain and behavior. 1. Dairy Sci. 60:947.
Journal of Dairy Science Vol. 75, No. 12, 1992
Animal, Dairy and Veterinary SCiences Department Utah State University
Logan 84322-4815
J. L. ALBRIGHT Animal Science Department Purdue University West Lafayette, IN 47906 D. V. ARMSTRONG Department of Animal Science University of Arizona Tucson 85721
W. W. FOSTER Department of Dairy Science South Dakota State University Brookings 57007 L. L. LARSON Department of Animal Science University of Nebraska Lincoln 68583-0908 ABSTRACT
triplet calves were obtained by transferring split embryos into recipients, one member of each pair was reared in a group, and the twin was reared in isolation. Early rearing previously had been found to affect growth, feed intake, dominance rank, and learning ability of calves, and, in our study, the subsequent milk yield of calves reared in isolation tended to average more than for calves in groups. Intraclass correlations between monozygous twin pairs for milk, fat, relative value milk, and relative value fat were lower than anticipated. These data indicate that preweaning isolation did not affect ftrst lactation milk yield traits. (Key words: calf rearing, behavior, ftrst lactation yield)
=
Holstein (n 323) calves in the herds of four experiment stations were reared individually (control) or ip isolation to 70 d of age to detennine whether isolation affected growth, behavior, and ftrst lactation yield. Treatment differences were not observed for average daily gain for BW at d 28, 56, or 70. Postweaning approach distance was measured in two herds (n = 122; n = 28). Detailed preand postweaning behaviors were reported in one herd (n 26). Isolation did not affect subsequent milk yield or culling percentages. In a second experiment, seven pairs of monozygous twins and a set of identical
=
Received April 13, 1992. Accepted July 10, 1992. 'Data are from the NC-1l9 Regional Research Project, Dairy Herd Management Strategies for Improved Decision Making and Profitability. This research was partially supported in the Utah Agricultura1 Experiment Station, Utah State University, Logan 84322-4810, approved as Journal Paper Nurnber 4308. Purdue Agricultura1 Experiment Station, approved as Journal Paper Number 13312. 1992 J Dairy Sci 75:3408-3415
Abbreviation key: ME MZ monozygous.
=
= mature
equivalent,
INTRODUCTION
Early rearing experience affects adult behavior in several species (1). Calves reared in
3408
3409
ISOLAnON EFFECTS ON GROWTH, BEHAVIOR, AND YIELD TABLE 1. Average daily gain from birth to weaning of calves reared individually or in isolation. Herd
Treatment
Number
Birth weight
28 d
56 d
70 d
(kg) Control Isolation 2 3 4
Control Isolation Control Isolation Control Isolation
29 29 59 63
43 40 40 40
.31 .29 .36 .38
.46 .46
.50 .50 .57 .55
13 13
44
.32 .30
.50 .47 .70 .69
.64
40
59 58
isolation are less dominant than calves reared in groups (1, 5, 10). However, results of a study involving monozygous (MZ) twin heifers indicated that a strong genetic component is associated with social dominance (7). Isolation also affected other behaviors, such as time spent eating and ability to traverse a T maze. The first lactation milk yield of Holstein calves reared in isolation exceeded that of their contemporaries reared in groups (1, 2, 6, 10). Rearing calves in isolation was associated with a significant reduction in SCC but did not affect health, reproductive parameters, or milk yield (8). One hypothesis attributed higher milk yield by isolated calves to their more docile nature and socialization to humans during early rearing experience (2), but additional research was recommended concerning the influence of early experience on adult function. The two experiments reported herein were initiated to study further the effects of isolation and group rearing in individual hutches described by Arave et al. (1) and to use MZ twins to remove genetic bias from performance comparisons. MATERIALS AND METHODS
This cooperative study involved researchers at five experiment stations. Four stations (Table 1) followed the same preweaning protocol, in which isolated calves (n = 163) were reared in hutches or pens that were surrounded with plywood (1.2 m high) to create a visual barrier. Calves could see open sky and could physically interact with their human caretaker but not with other calves. TIle pens and hutches
.51 .53
44
42
.68 .76 .74
used for unisolated calves (n = 160) were similar but lacked a visual barrier. Calves were removed from their dams as soon as practicable after birth, moved to individual pens, and hand-fed their first colostrum. Calves were assigned randomly to treatments, but a balance was maintained based on sire's PD and dam's cow index. Each station followed its normal feeding regimen for both treatments. Calves were weaned at approximately 10 wk of age. Approach distance was measured at weaning in herds 2 (n 122) and 3 (n 26). When a calf was put in an enclosed pen, the approach distance was how close that calf would come to a person kneeling in the pen. Approach distance was determined at 5 and 10 min. Weaned calves were returned to the standard herd management practices. Birth weight; BW at 4, 8, and 10 wk; breeding and calving age; postpartum BW; first lactation yield; sire PD; dam cow index; and social behavior were determined, although complete data were not available from all stations. Data from 243 calves (cows when data were obtained, n = 48, 89, 18, and 88 from herds 1, 2, 3, and 4, respectively) were analyzed. At the Utah station, MZ twins were obtained by transferring split embryos into recipients (n = 181). One MZ twin was assigned randomly to be reared in isolation, and the other was reared in a group of five or six calves. Embryos were transferred at Ruann Dairy, a large commercial dairy near Fresno, CA. Seven pairs of MZ twin heifers and one set of identical triplets resulted from the embryo transfer. Two of the triplet calves were reared in isolation. Before calves were weaned,
=
=
Journal of Dairy Science Vol. 75, No. 12. 1992
3410
ARAVE ET AL.
TABLE 2. Effect of rearing calves in isolation on approach distances postweaning (n = 122). Time observed 1 Week
Day
Treatment
5 min
I I 2
Isolation Isolation Control Control
3.96 5.18 4.88 4.27
4.88 5.49 5.79 5.18
I 2 I 2
Isolation Isolation Control Control
5.18 5.49 6.10 6.10
5.49 6.10 5.79 6.40
10 min (m)
2
2
1Time
after first introduction to an observer.
they were reared separately from other calves on the farm, but the feeding, vaccination schedules, and management practices were otherwise similar to those used at the dairy. Calves in isolation were reared in polyvinyl dome hutches separated by 1.2 x 2.4-m plywood panels. A group pen consisted of three standard wooden hutches placed side by side that faced three similarly arranged hutches located across 1.5 m of space. Space between rows of hutches was enclosed by a locking manger on one side and a panel on the other. The ends of the hutches were removed to allow access by all calves. Behavior was evaluated when calves were 4 to 6 wk old (7). At weaning, calves were put through a T maze five times on 3 consecutive d. They were then reared in groups containing 80 calves.
(ME) milk, and ME fat were the dependent variables. In the study involving six pairs of MZ twins, ME milk, fat, and FCM and relative value milk, fat, and FCM were the dependent variables. The general linear models procedure of SAS (9) was used in data analyses. RESULTS AND DISCUSSION Experiment 1
At one station, the difference in average daily gain of 13 calves reared in isolation
2.7m
Statistical Analysis
Data on behavioral observations were analyzed by least squares ANOVA techniques under a completely randomized design with treatment (isolation vs. individual) as the main effect. Analyses were conducted separately for group 1 and group 2 data and for the two groups pooled in one data set. Data from the four experiment station herds were pooled to analyze the effects of rearing on subsequent milk yield. Treatment, herd, and treatment by herd interaction effects were included in the model along with birth weight, age at calving, sire's PD milk and fat, and dam's cow index milk and fat as covariates. Records missing any covariate value were not used in the analysis. Fat-corrected milk, mature equivalent Journal of Dairy Science Vol. 75, No. 12, 1992
.
Corri dar 13.7 m
Door
.
Feed room 2 .7m
7m Figure l. Approach score testing area for calves postweaned from rearing in isolation or individual hutches (n = 26).
3411
ISOLATION EFFECI'S ON GROWTH, BEHAVIOR, AND YIELD TABLE 3. Effect of isolation rearing on approach distance = 26).
(n
Conditions
Group II
Group 22 (m)
Treatment Isolation Control
2.62 3.23
2.96 2.68
Observer location Feed room Corridor
2.383.51 b
2.383.26b
Observer type Familiar male Unfamiliar male Familiar female Unfamiliar female
3.08b 4.33b 2.132.19-
3.54b 3.35 b .941 3.44b
Test time 5 min 10 min
3.02 2.83
2.77 2.87
=
and herd 3 (n 26). In wk 1, isolated calves tended to let observers approach more closely than did calves reared in groups, but the difference was not significant (Table 2). A second approach experiment (herd 3, n 26) was conducted in a modified testing arena (Figure I). The only significant (P < .05) differences occurred when calves were all allowed to circle the observer. Under these conditions, some significant (P < .0I) differences in approach scores (Table 3) occurred that did not involve the effects of isolation but, instead, involved the familiarity of a calf with the observer and the gender of the observer (Table 3). Calves in herd 3 were continuously observed for 24 h to determine the time spent in 14 behaviors and activities and calf position in the stalls (Table 4). Calves reared in isolation spent significantly (P < .01) less time at the back of stalls and more time (P < .02) at the side of stalls, reflecting differences in behavioral thermoregulation. Calves in group I were raised during the winter, and calves in the control group had less protection from the elements than did calves reared in isolation, which may explain why calves in the control group spent more time in the most protected location at the rear of the stall. Standing time may be the behavior that is most indicative of stress. In group 2, calves reared in isolation spent significantly (P < .02) more time standing than did control calves. At our station (herd 3) we recorded the time that calves socialized with other calves (most
=
a.bMeans in columns in same group within condition with different superscripts differ: observer lotation (P < .05), observer type (P < .01). IFall to winter 1984. 2Spring to sununer 1985.
versus 13 calves reared individually from 8 to 10 wk preweaning was significant (P < .05). However, overall change in preweaning BW, a traditional measure of animal well-being, was not affected by isolation (Table I). Approach distances were measured I and 2 wk postweaning (after calves had been housed in a group) at two stations: herd 2 (n 122)
=
TABLE 4. Behavioral and general activity and stall orientation by heifer calves during 24-h d (n
Group 22
Group 11 Control
= 26).
Isolation
Control
Isolation
(%)
Activity Standing Lying head up Lying head down Stall orientation Front Back Side
19 50 31
30 44 26
2755 19
45b 47 8
42 57l
59 24b 18b
43 40 17
45 47 8
Il
a.bMeans in rows in the same group with different superscripts differ: standing (P < .02), back (P < .01), side (P < .02). 'Fall to winter 1984. 2Spring to sununer 1985. Journal of Dairy Science Vol. 75, No. 12, 1992
3412
ARAVE ET AL.
TABLE 5. Maintenance behavior of calves reared individually or in isolation preweaning (n
Group 22
Group 11 Activity
Control
= 26).
Isolation
Control
Isolation
(min) Eating Drinking Eliminating Ruminating Investigating Socializing Playing Grooming
56 5 2 217 98 121 32
34
61
5 1 221 201 4b 0 32
34
120 50 2 352 253 4 4 50
1 377 123
11 1 55
-.bMeans in rows within groups with different superscripts differ (P < .05). IFalI to winter 1984. 2S pring to sununer 1985.
commonly by nuzzling and licking each other's heads and faces) and with humans (Table 5). Isolated calves socialized significantly (P < .05) less than control calves. Vocalizations (herd 3) for individual calves were extremely variable and are probably not a reliable indicator of stress (Table 6). Isolation did not significantly affect the number of times that calves vocalized, which was consistent with the results of similar studies (1, 10) in which calves reared in isolation and in individual pens were monitored at weaning. Creel and Albright (3, 4) hypothesized that calfhood isolation may subliminally stimulate the adrenal cortical complex and thereby enhance responsiveness to acute stress as adults.
When they (3, 4) measured urinary cortisol concentrations at biweekly intervals preweaning and blood serum cortisol immediately after calves were exposed to an acute stress, the difference in cortisol concentrations in urine was not significant, but the difference in the serum cortisol concentrations of isolated (13.2 nglml) and control (9.4 nglml) calves (4) was significant (P < .01). The difference in the incidence of illness between the two groups of calves was not significant, which indicates that rearing in isolation did not suppress the immune system. Health records from the other stations involved in the study also failed to show a difference in the health of the two groups of calves.
TABLE 6. Vocalization, expressed as number of occurrences in a 2-h period (n = 26). Group 22
Group 11 Control Heifer I
2 3
13 13
o
4
o
5 6
4 64
Isolation
2
o o
Heifer 7
8
15.5 24
SE IFall to winter 1984. 2Spring to sununer 1985.
Journal of Dairy Science Vol. 75. No. 12, 1992
Isolation
o 1 o
51
1
9 10
4
131 6
11
2
12
3
13
X
Control
23.3 53
8 8
o
o 14 o o
1.4 2
11.6 18
3413
ISOLATION EFFECTS ON GROWTH, BEHAVIOR, AND YIELD
TABLE 7. Least squares means for measures of milk yield of heifers reared individually or in isolation (243 cows in four experiment station herds). Yield characteristic 1 Treatment
FCM
SE
MEM
Control Isolation
8782 8852
156 137
8776 8841
SE
MEF
SE
176 154
308 310
5 5
(kg)
lMEM
= Mature equivalent milk; MEF = mature equivalent fat.
Milk yields of cows reared in isolation averaged more than those of control cows (+70 kg of FCM, +65 kg of ME milk, and +2 kg of ME fat), but none of the differences was significant (Table 7). The difference in mean FCM, ME milk, and ME fat between the groups was less than 1%. The type of rearing regimen did not significantly affect yield traits (Table 8). Several factors influenced milk yield, but findings did not support the results of another study (1) in which FCM yield of isolates was substantially greater than that of cows reared in groups or individually without isolation. The difference in FCM was less between cows reared individually and isolated cows than between cows reared in groups and isolated cows (1).
The results of this type of experiment could be biased if a greater proportion of low yielding cows in one group were culled before completion of their first lactations, which prob-
ably did not occur in this study. Less than 10% of the cows in this study (263 of the original 323 calves had fIrst lactations; 95 culled cows included 5 with second lactations) were culled for low yield, and the number of cows culled because of treatment for reproductive or health problems was nearly equal in both groups (Table 9). Experiment 2
The effects of early rearing on growth, feed intake, social development, survival, and learning ability were reported earlier (7). Briefly, no significant differences existed in average daily gain or in feed intake between isolated and control calves, although calves reared in groups spent significantly (P < .05) more of a 24-h d eating than did isolated calves (10.9 vs. 5.4%). Social facilitation appears to influence calves reared in groups, as was also evident in
TABLE 8. Probability values and significance of sources of variation in parameters related to fust lactation milk yield of heifers (n 242) reared in isolation and in standard hutches.
=
Dependent variables 1 Source 1
df
FCM
MEM
MEF
Treatment Herd (H) TxH Birth weight Age PDM PDF CIM CIF
1 3 3 1 1 1 1 1 1
.11 10.59** .95 .03 .07 6.04* .90 6.40* .22
.08 19.08** .75
.12 6.72** .98
=
=
(n
lMEM Mature equivalent milk; MEF mature equivalent fat; PDM dam's cow index milk; ClF = dam's cow index fat.
.13 .24 18.99** .57 21.16** 3.51
0 0 .33 5.08* .25 5.56*
=sire's PO milk; PDF =sire's PO fat; CIM =
*p < .05. **p < .01. Journal of Dairy Science Vol. 75, No. 12, 1992
3414
ARAVE ET AL.
TABLE 9. Reasons for disposal of cows reared individually or isolated (data from 263 cows in four herds; 5 of 95 culled cows had two lactations at time of analysis). Reason
Individual (n)
Low yield 15 Reproductive failure 15 Health 9 Other 9 Unknown 5 Mean age at disposal. mo
Isolation
(%)1
(n)
(%)1
28 28 17 17 9
9 11 7 10 5
21 26 17 24 12
39.38
38.32
1Percentage of all cows culled.
another study (10). The time spent resting or the side on which calves rested (laterality) did not differ by treatment. Social behavior was assessed when heifers were 15 to 17 mo of age, and no relationship was found between dominance rank and either age or BW, but the intraclass correlation (r = .93) between twin pairs for dominance indicated that dominance was associated with genotype. During the ftrst 2 d of a 3-d postweaning trial, isolated calves reached the goal in a T maze signiftcantly (P < .05) sooner than calves reared in groups. We tried to determine approach distance when calves were between 5 and 7 mo of age, but, regardless of treatment, calves were too wary of an observer to allow this trait to be measured accurately. The "enhanced humananimal bond" (7) seemed to have been extinguished in these heifers, perhaps because of the relatively large groups (approximately 80 calves) in which calves were reared after they were weaned at 70 d. The MZ twin cows that were reared in isolation had greater yield (+221 kg of milk, +7 kg of fat, and +200 kg of FCM) than the twins reared in groups, but the differences were not significant (Table 10). Largest differ-
ences occurred for relative value milk (deviation of a cow from the base ME, which is calculated each test day by averaging the ME yield of each cow on the barn sheet) (515 kg), and for relative value FCM (77 kg). Relative value provides a more accurate evaluation of a cow's performance than her lactation average because it compares milk yield with that of herdmates that calved in the same season and that receive the same feeding and management regimens. The low intraclass correlations between MZ twin pairs for yield traits (milk, r' = .34; fat, r' = -.36; relative value milk, r' = .34; relative value fat, r' = .26) were anomalous because differences between MZ twins should largely reflect environmental factors. CONCLUSIONS
Before calves were weaned, they were reared in either isolation or individual housing to determine whether isolation affected growth, behavior, or yield characteristics. Rearing in isolation had some effects on where calves stood in their stall and on socialization but did not affect health or yield characteristics. Similarly, no differences existed in the yields of MZ twin pairs, one of which had been reared in isolation and one of which had been reared in a group, although treatment-related differences existed in the time that calves spent eating and in their performance in a T maze. The yield differences between MZ twins were far greater than expected. Rearing in isolation had minimal, shortterm effects on preweaning behavior. Yield characteristics were not enhanced by rearing in isolation, unlike the findings of previous studies (1, 2, 6, 10) that involved fewer calves. The results also show the utility of using MZ twins in management studies.
TABLE 10. Milk yield comparisons of monozygous twin cows reared in a group or in isolation preweaning.
Mature equivalent Treatment
n
Milk
Fat
Relative value
FCM
Milk
Fat
FCM
543 1058
10 14
401 478
(kg) Group Isolation
6 6
12.324 12.545
Journal of Dairy Science Vol. 75. No. 12. 1992
423 430
11,277 11,477
ISOLAnON EFFECTS ON GROWTH, BEHAVIOR, AND YIELD
REFERENCES I Arave, C. W., C. H. Mickelsen, and 1. L. Walters. 1985. Effect of early rearing experience on subsequent behavior and production of Holstein heifers. J. Dairy Sci. 68:923. 2 Arave, C. W., and V. D. Warnick. 1979. Heifers raised in isolation milked well at Utah State. Hoard's Dairyman 124(4):618. 3 Creel, S. R., and J. L. Albright. 1987. Early experience. Page 251 in Farm Animal Behavior. The Veterinary Clinics of North America: Food Animal Practice. Vol. 3. E. O. Price, ed. W. B. Saunders Co., Philadelphia, PA. 4 Creel, S. R., and J. L. Albright. 1988. The effects of neonatal social isolation on the behavior and endocrine function of Holstein calves. Appl. Anim. Behav. Sci. 21 :293. 5 Donaldson, S. L. 1967. The effect of early feeding and rearing experiences on the dominance, aggression, and
3415
submission behavior of young heifer calves. M.S. Thesis, Purdue Univ., West Lafayette, IN. 6 Donaldson, S. L., J. L. Albright, and W. C. Black. 1972. Primary social relationships and cattle behavior. Proc. Indiana Acad. Sci. 81:345. 7 Purcell. D., and C. W. Arave. 1991. Isolation vs. group rearing in monozygous twin heifer calves. Appl. Anim. Behav. Sci. 31:147. 8 Rakes, A. H. 1988. The effect of raising heifers in isolation during the first ten weeks on their growth and performance. J. Dairy Sci. 71(Suppl. 1): 283.(Abstr.) 9 VAXlYMS Operating System. 1986. Production Release 5.16. SAS Inst. Inc., Cary, NC. 10 Warnick, V. D., C. W. Arave, and C. H. Mickelsen. 1977. Effects of group, individual, and isolated rearing of calves on weight gain and behavior. 1. Dairy Sci. 60:947.
Journal of Dairy Science Vol. 75, No. 12, 1992
