Lactation, Health, and Reproduction of Dairy Cows Receiving Dally Injectable or Sustained-Release Somatotropin XIN ZHAO, JOHN H. BURTON, and BRIAN W. McBRIDE Department of Animal and Poultry Science University of Guelph Guelph, ON, Canada N1G ';NJ1 ABSTRACT
(12). Numerous trials using daily injectable formulation of bST have confirmed that bST has the potential to increase milk production dramatically in well-managed dairy herds [reviewed by McBride et al. (12)]. Fewer studies were conducted to determine the response of dairy cows to bST administrated in sustained-release formulation (2, 7, 14, 20, 23). In addition, little effort was made to compare the performance of cows receiving bST in a sustained-release formulation versus a daily injectable formulation. The objective of this study was to measure production responses and to compare the effects of the bST sustained-release and daily injectable formulations on reproductive performance, mastitis, and general cow health when treatments were started 4 to 5 wk postpartum.
Seventy-four Holstein cows (26 primiparous) were utilized to compare the efficacy and safety of sustainedrelease versus daily injectable formulations of recombinant bST. Twenty-foUT control cows were injected biweekly with oil microsphere; 25 cows were injected biweekly with 350 mg of bST microsphere; and 25 cows were injected daily with 10.3 mg of bST. Injections were initiated between wk 4 and 5 of lactation and continued for 280 d. Administration of bST caused a moderate increase in milk and FCM production and improved the efficiency of feed and energy conversions. Most health-related and reproduction-related variables did not differ among treatment groups. However, incidence of teat and udder disorders and feet and leg problems tended to be higher during the 40-wk injection period for the bST-treated cows than for the control cows. Incidence of GnRH therapy and number of days to first service were higher for daily bSTtreated cows than for controls. No differences existed between sustained-release and daily bST-treated cows for any parameters monitored. (Key words: somatotropin, milk production, health)
MATERIALS AND METHODS Treatment Groups
Abbreviation key: BWG = BW gain, EI = energy intake, Fe = feed conversion. INTRODUCTION
The effectiveness of bST for increasing milk production has been well documented
Seventy-four lactating Holstein cows (26 primiparous) from the University of Guelph (Elora Dairy Research Center) were assigned to treatment groups that included 24 control cows (5 ml/14 d), 25 cows treated with daily injectable bST (10.3 mgld per cow), and 25 cows treated with sustained-release bST (350 mg/14 d per cow). All treatments were administrated by subcutaneous injections on alternating sides of body near the gluteal or semitendonosis muscles for daily injectable bST or just posterior to lower scapulas for sustained-released bST. The injections started between wk 4 and 5 postpartum and continued for 40 wk or until production dropped below 10 kg/d. Management
Received March 3, 1992. Accepted July 20, 1992. 1992 J Dairy Sci 75:3122-3130
Management practices were the same as reported previously (3, 8, 13). Briefly, cows on 3122
3123
TWO FORMULATIONS OF SOMATOTROPIN TABLE 1. Diet switching criteria, ration composition, and feed analyses. Forage:concentrate ratio and diet switching criteria
Criteria Ingredients Com silage Haylage High moisture com Alfalfa meal Soybean meal Dry hay Minerals and salt Feed analysis, %, DM basis
DM CP
Fat Ash ADF NDF Ca P
NEL Mcal/kg of DM
as fed)
(% OM)
(%
21.4 18.7 32.3 7.5 8.4 10.8
32.8 28.7 22.3 4.4 4.8 6.6 .5
.8
74:26 M < 21 kg P < 12 kg
60:40 21 kg :S M :S 30 12 kg :S P < 18 kg
51:49 MI ~ 30 kg p2 ~ 18 kg
(% DM)
(% as fed)
38.6 38.6 19.5
37.1 37.1 24.2
43.3 43.3 12.7
5.8
2.8
.7
.3
1.1
.5
.9
.3
(% OM)
(%
29.8 29.8 33.5
as fed)
51:49
60:40
74:26
(n = 8)
(n
(n
50.10 18.21 3.17 6.18 24.05 35.48 .83 .51 1.61
43.25 17.18 3.80 6.47 22.78 35.00
= 8)
.92 .54 1.58
= 8)
38.05 15.70 4.15 6.93 28.13 39.63 1.11 .49 1.48
IMilk production (kilograms) for multiparous cows. 2Milk production (kilograms) for primiparous heifers.
trial were milked in parlors twice daily. Cows were fed for ad libitum intake one of three TMR, according to milk production and body condition. Production criteria for diet switching were assessed separately for multiparous and primiparous cows. Diet switching criteria, ration composition, and 40-wk trial average feed analyses are reported in Table 1. Prior to the initiation of bST treatments, all lactating cows were offered a 51:49 forage to concentrate diet. Data Collection
Milk production was recorded at each milking. The a.m. and p.m. records were then averaged by week to give weekly milk production. The a.m. and p.m. milk samples were analyzed once weekly for milk fat, protein, and lactose concentrations using an infrared spectrometer and for SCC using a Coulter Counter (Coulter Electronics, Hialeah, FL). Estimates of 3.5% FCM were calculated from total milk production and the once weekly estimate of milk fat concentration.
Orts also were collected three times weekly and used in the estimation of weekly DM!. Weekly feed samples were composited at monthly intervals and analyzed for OM, CP, ether extract, ash, Ca, P, ADF, and NDF (1). Energy intake (EI) was estimated from the individual DMI and the average NEL supplied by the diet consumed during the given week. The NEL values for individual feed ingredients were taken from NRC (15) or Ensminger et al. (5). Cow BW were recorded once weekly at 1000 h during the ftrst 4 wk of the trial prior to bST administration and every 2 wk thereafter until the end of the trial. Rates of BW gain (BWG) were estimated by linear regression of weight on time for each of the trial periods. The only exception was BWG over the 40-wk period following onset of administration of bST. In this case, estimates of BW at the beginning and the end of the 40-wk period were calculated from linear regressions over the ftrst and last 10 wk of the trial period. The incidence of nine health problems requiring treatment of clinical symptoms was Journal of Dairy Science Vol. 75, No. 11. 1992
3124
ZHAO ET AL.
recorded, including displaced abomasum, edema, feet and leg problems, ketosis, mastitis, milk fever, off feed, pneumonia, and teat and udder problems (other than mastitis or edema). Incidence was recorded per cow as an all or none variable. Incidence data per cow per health problem then were tallied by bST treatment groups for statistical analysis. Treatments for reproductive problems included pyometritis or metritis, cystic ovaries, prostaglandin therapy, GnRH injections, and a separate category to include any other minor treatment. Under a similar scoring system as previously described for health variables, these reproductive measurements were recorded as incidence variables. Reproductive performance per se was assessed as numbers of days open, days to first service, and numbers of AI per conception.
the pre-bST treatment period average milk production (all traits except BW and BWG) or average BW or BWG (for analyses of BW and BWG only) of cow ijk, Aijk = the age at calving of cow ijk, b 1, b2' and b3 = regression coefficients, Tj = the fixed effect of treatment group j (control, daily injection, or sustained-release), and a random error term. Health and reproductive disorder and therapy incidences were compared by chi-square analysis. Significance was defined at P < .10 unless otherwise noted. RESULTS
Statistical Analysis
Statistical analyses were the same as detailed previously (8). Data were divided into the 4-wk pre-bST administration period and the 40-wk bST administration period. The 40-wk treatment period was further divided into subperiods 1 to 4. Each period covered lO-wk intervals. All traits were analyzed in the natural scale except SCC, which was transformed first by taking natural logarithms to ~chieve a normal distribution. With the exceptIOn of feed conversion (FC), the data analyzed were the averages, or the regression estimates in the case of BWG, in each of the periods; FC and energetic FC were estimated as average DMI and EI divided by average FCM production in each of the periods. All analyses were conducted using SAS (17). Continuous variables were analyzed using the linear model, Yijk
+ b 1M ijk + b2 Aijk + b3A~k + Tj + eijk,
= ).!
where Y = the observation in a treatment period, ).! = the sample mean for the treatment period, Journal of Dairy Science Vol. 75. No. 11. 1992
Production Response
Treatment Period. A moderate (P < .10) 6 to 9% increase in milk and FCM production occurred in cows receiving daily injectable or sustained-release bST, but no significant increases in DMI and EI (Table 2) occurred. In addition, primiparous cows responded to bST treatments more than did multiparous cows in milk and FCM production (Table 3). The bST treatments resulted in lower feed and energy conversions. Except for a significant (P < .05) 4% increase in milk protein concentration in the daily injection group compared with the control group, bST treatments had no effect on milk composition or SCC content of milk. Similarly, bST treatments had no effect on BWG. No differences existed in any production traits between the daily injection bST group and the sustained-release bST group. Periods of bST Treatment. Least squares means, standard errors, and associated significance for the effect of bST treatment on milk production and on intake and FC traits during periods 1 to 4 are in Table 4. Administration of bST did not result in significant increases in FCM production for the first two periods but increased FCM approximately 14% in the last two periods (P < .10). These increases translated into an absolute increase of
3125
TWO FORMULATIONS OF SOMATOTROPIN
TABLE 2. Least squares means, standard errors, and associated significance for the effect of treatment with bST on performance during the 4Q-wk treatment period. Contrast bST Treatments! Trait2
CO
DI
X SE Milk, kgld 25.60 .88 3.5% FCM, kgld 26.53 .90 DMI, kgld 20.41 .51 FC, kg of DMllkg of FCM .83 .02 Energy intake, Meal of 30.46 1.16 NEIld EFC, Mcal of NELlkg of FCM 1.31 .04 Fat, % 3.73 .12 Protein, % 3.29 .06 Lactose, % 5.07 .07 SCC, IOl;e cellslml 3.77 .25 BW, kg 671 10 BW Gain, kgld .51 .06 !CO
= Control,
DI
= daily
injection, SR
SR
X 27.29 28.36 20.52
SE .82 .85 .48
.76
.02
X
DI
CO
CO
YS.
YS.
YS.
DI
SR
SR
•
t
•
SE
27.78 28.29 20.76
.88 .91 .52
NS
NS
NS3 NS NS
.77
.02
••
•
NS
32.10 1.10
31.52 1.18
NS
NS
NS
1.22 .03 3.79 .11 3.42 .06 5.03 .07 4.01 .25 647 10
1.23 .04 3.64 .12 3.34 .06 5.09 .07 3.98 .26 651 10 .43 .06
•
•
NS
NS NS
NS NS NS NS
NS
NS
NS NS NS NS NS NS NS
.49
.05
• ...
t
= sustained-release.
2FC = Feed conversion, EPC = energetic Pc. 3p > .10.
• p < .05. ••p < .01. tp < .10.
approximately 2 kg/d of milk per cow over all stages of lactation. Feed intake was lower in period 1 and tended to be elevated in later periods for the daily injection and the sustained-release groups. Similarly, EI did not change in the frrst two periods but significantly increased in period 3 (7%) and period 4 (10%) for the daily injection group and in period 4 (13%) for the sustained-release group. Conversely, the FC energetic and FC were decreased (higher efficiency) for the daily injection and the sustained-release groups, especially in earlier periods. Except for energetic FC, no statistically significant differences existed between the daily injection and the sustained-release groups. Least squares means, standard errors, and associated significance for the effect of bST treatment during periods 1 to 4 of lactation on milk composition and BW traits are in Table 5. Except for a significantly lower BW in periods 2 and 3, treatment with sustained-release bST did not affect milk composition, SCC, or BWG. However, treatment with daily injecta-
ble bST significantly (P < .05) increased milk lactose concentrations in periods 2 to 4 and milk protein concentrations in periods 3 and 4. Analysis of Health Variables
Table 6 shows that most health-related variables were not different among treatment groups before, during, or after the 40-wk injection period; however, trends were toward higher incidence of teat and udder disorders and feet and leg problems during the 40-wk injection period in the bST-treated groups than in the control group. The incidence of reproductive problems in control and treated cows is in Table 7. Days open and number of inseminations were used as indices of reproductive efficiency. Least squares means and significance for the effect of bST treatments on these two parameters are in Table 8. Incidence of infections leading to pyometritis or metritis was not different among treatment groups. Similarly, number of services per conception and days open were not Journal of Dairy Science Vol. 75, No. II, 1992
3126
ZHAO ET AL.
affected by bST treatments. However, incidence of GnRH therapy and number of days to first service were higher for cows receiving bST daily injection than for control cows. No differences existed between cows receiving sustained-release and daily injections of bST for any health and reproductive variables monitored.
~ ~~~~~C!i VJ
-
--
DISCUSSION
'"
i~
.S!
II
;E,s 1>
(12). Numerous trials using daily injectable formulation of bST have confirmed that bST has the potential to increase milk production dramatically in well-managed dairy herds [reviewed by McBride et al. (12)]. Fewer studies were conducted to determine the response of dairy cows to bST administrated in sustained-release formulation (2, 7, 14, 20, 23). In addition, little effort was made to compare the performance of cows receiving bST in a sustained-release formulation versus a daily injectable formulation. The objective of this study was to measure production responses and to compare the effects of the bST sustained-release and daily injectable formulations on reproductive performance, mastitis, and general cow health when treatments were started 4 to 5 wk postpartum.
Seventy-four Holstein cows (26 primiparous) were utilized to compare the efficacy and safety of sustainedrelease versus daily injectable formulations of recombinant bST. Twenty-foUT control cows were injected biweekly with oil microsphere; 25 cows were injected biweekly with 350 mg of bST microsphere; and 25 cows were injected daily with 10.3 mg of bST. Injections were initiated between wk 4 and 5 of lactation and continued for 280 d. Administration of bST caused a moderate increase in milk and FCM production and improved the efficiency of feed and energy conversions. Most health-related and reproduction-related variables did not differ among treatment groups. However, incidence of teat and udder disorders and feet and leg problems tended to be higher during the 40-wk injection period for the bST-treated cows than for the control cows. Incidence of GnRH therapy and number of days to first service were higher for daily bSTtreated cows than for controls. No differences existed between sustained-release and daily bST-treated cows for any parameters monitored. (Key words: somatotropin, milk production, health)
MATERIALS AND METHODS Treatment Groups
Abbreviation key: BWG = BW gain, EI = energy intake, Fe = feed conversion. INTRODUCTION
The effectiveness of bST for increasing milk production has been well documented
Seventy-four lactating Holstein cows (26 primiparous) from the University of Guelph (Elora Dairy Research Center) were assigned to treatment groups that included 24 control cows (5 ml/14 d), 25 cows treated with daily injectable bST (10.3 mgld per cow), and 25 cows treated with sustained-release bST (350 mg/14 d per cow). All treatments were administrated by subcutaneous injections on alternating sides of body near the gluteal or semitendonosis muscles for daily injectable bST or just posterior to lower scapulas for sustained-released bST. The injections started between wk 4 and 5 postpartum and continued for 40 wk or until production dropped below 10 kg/d. Management
Received March 3, 1992. Accepted July 20, 1992. 1992 J Dairy Sci 75:3122-3130
Management practices were the same as reported previously (3, 8, 13). Briefly, cows on 3122
3123
TWO FORMULATIONS OF SOMATOTROPIN TABLE 1. Diet switching criteria, ration composition, and feed analyses. Forage:concentrate ratio and diet switching criteria
Criteria Ingredients Com silage Haylage High moisture com Alfalfa meal Soybean meal Dry hay Minerals and salt Feed analysis, %, DM basis
DM CP
Fat Ash ADF NDF Ca P
NEL Mcal/kg of DM
as fed)
(% OM)
(%
21.4 18.7 32.3 7.5 8.4 10.8
32.8 28.7 22.3 4.4 4.8 6.6 .5
.8
74:26 M < 21 kg P < 12 kg
60:40 21 kg :S M :S 30 12 kg :S P < 18 kg
51:49 MI ~ 30 kg p2 ~ 18 kg
(% DM)
(% as fed)
38.6 38.6 19.5
37.1 37.1 24.2
43.3 43.3 12.7
5.8
2.8
.7
.3
1.1
.5
.9
.3
(% OM)
(%
29.8 29.8 33.5
as fed)
51:49
60:40
74:26
(n = 8)
(n
(n
50.10 18.21 3.17 6.18 24.05 35.48 .83 .51 1.61
43.25 17.18 3.80 6.47 22.78 35.00
= 8)
.92 .54 1.58
= 8)
38.05 15.70 4.15 6.93 28.13 39.63 1.11 .49 1.48
IMilk production (kilograms) for multiparous cows. 2Milk production (kilograms) for primiparous heifers.
trial were milked in parlors twice daily. Cows were fed for ad libitum intake one of three TMR, according to milk production and body condition. Production criteria for diet switching were assessed separately for multiparous and primiparous cows. Diet switching criteria, ration composition, and 40-wk trial average feed analyses are reported in Table 1. Prior to the initiation of bST treatments, all lactating cows were offered a 51:49 forage to concentrate diet. Data Collection
Milk production was recorded at each milking. The a.m. and p.m. records were then averaged by week to give weekly milk production. The a.m. and p.m. milk samples were analyzed once weekly for milk fat, protein, and lactose concentrations using an infrared spectrometer and for SCC using a Coulter Counter (Coulter Electronics, Hialeah, FL). Estimates of 3.5% FCM were calculated from total milk production and the once weekly estimate of milk fat concentration.
Orts also were collected three times weekly and used in the estimation of weekly DM!. Weekly feed samples were composited at monthly intervals and analyzed for OM, CP, ether extract, ash, Ca, P, ADF, and NDF (1). Energy intake (EI) was estimated from the individual DMI and the average NEL supplied by the diet consumed during the given week. The NEL values for individual feed ingredients were taken from NRC (15) or Ensminger et al. (5). Cow BW were recorded once weekly at 1000 h during the ftrst 4 wk of the trial prior to bST administration and every 2 wk thereafter until the end of the trial. Rates of BW gain (BWG) were estimated by linear regression of weight on time for each of the trial periods. The only exception was BWG over the 40-wk period following onset of administration of bST. In this case, estimates of BW at the beginning and the end of the 40-wk period were calculated from linear regressions over the ftrst and last 10 wk of the trial period. The incidence of nine health problems requiring treatment of clinical symptoms was Journal of Dairy Science Vol. 75, No. 11. 1992
3124
ZHAO ET AL.
recorded, including displaced abomasum, edema, feet and leg problems, ketosis, mastitis, milk fever, off feed, pneumonia, and teat and udder problems (other than mastitis or edema). Incidence was recorded per cow as an all or none variable. Incidence data per cow per health problem then were tallied by bST treatment groups for statistical analysis. Treatments for reproductive problems included pyometritis or metritis, cystic ovaries, prostaglandin therapy, GnRH injections, and a separate category to include any other minor treatment. Under a similar scoring system as previously described for health variables, these reproductive measurements were recorded as incidence variables. Reproductive performance per se was assessed as numbers of days open, days to first service, and numbers of AI per conception.
the pre-bST treatment period average milk production (all traits except BW and BWG) or average BW or BWG (for analyses of BW and BWG only) of cow ijk, Aijk = the age at calving of cow ijk, b 1, b2' and b3 = regression coefficients, Tj = the fixed effect of treatment group j (control, daily injection, or sustained-release), and a random error term. Health and reproductive disorder and therapy incidences were compared by chi-square analysis. Significance was defined at P < .10 unless otherwise noted. RESULTS
Statistical Analysis
Statistical analyses were the same as detailed previously (8). Data were divided into the 4-wk pre-bST administration period and the 40-wk bST administration period. The 40-wk treatment period was further divided into subperiods 1 to 4. Each period covered lO-wk intervals. All traits were analyzed in the natural scale except SCC, which was transformed first by taking natural logarithms to ~chieve a normal distribution. With the exceptIOn of feed conversion (FC), the data analyzed were the averages, or the regression estimates in the case of BWG, in each of the periods; FC and energetic FC were estimated as average DMI and EI divided by average FCM production in each of the periods. All analyses were conducted using SAS (17). Continuous variables were analyzed using the linear model, Yijk
+ b 1M ijk + b2 Aijk + b3A~k + Tj + eijk,
= ).!
where Y = the observation in a treatment period, ).! = the sample mean for the treatment period, Journal of Dairy Science Vol. 75. No. 11. 1992
Production Response
Treatment Period. A moderate (P < .10) 6 to 9% increase in milk and FCM production occurred in cows receiving daily injectable or sustained-release bST, but no significant increases in DMI and EI (Table 2) occurred. In addition, primiparous cows responded to bST treatments more than did multiparous cows in milk and FCM production (Table 3). The bST treatments resulted in lower feed and energy conversions. Except for a significant (P < .05) 4% increase in milk protein concentration in the daily injection group compared with the control group, bST treatments had no effect on milk composition or SCC content of milk. Similarly, bST treatments had no effect on BWG. No differences existed in any production traits between the daily injection bST group and the sustained-release bST group. Periods of bST Treatment. Least squares means, standard errors, and associated significance for the effect of bST treatment on milk production and on intake and FC traits during periods 1 to 4 are in Table 4. Administration of bST did not result in significant increases in FCM production for the first two periods but increased FCM approximately 14% in the last two periods (P < .10). These increases translated into an absolute increase of
3125
TWO FORMULATIONS OF SOMATOTROPIN
TABLE 2. Least squares means, standard errors, and associated significance for the effect of treatment with bST on performance during the 4Q-wk treatment period. Contrast bST Treatments! Trait2
CO
DI
X SE Milk, kgld 25.60 .88 3.5% FCM, kgld 26.53 .90 DMI, kgld 20.41 .51 FC, kg of DMllkg of FCM .83 .02 Energy intake, Meal of 30.46 1.16 NEIld EFC, Mcal of NELlkg of FCM 1.31 .04 Fat, % 3.73 .12 Protein, % 3.29 .06 Lactose, % 5.07 .07 SCC, IOl;e cellslml 3.77 .25 BW, kg 671 10 BW Gain, kgld .51 .06 !CO
= Control,
DI
= daily
injection, SR
SR
X 27.29 28.36 20.52
SE .82 .85 .48
.76
.02
X
DI
CO
CO
YS.
YS.
YS.
DI
SR
SR
•
t
•
SE
27.78 28.29 20.76
.88 .91 .52
NS
NS
NS3 NS NS
.77
.02
••
•
NS
32.10 1.10
31.52 1.18
NS
NS
NS
1.22 .03 3.79 .11 3.42 .06 5.03 .07 4.01 .25 647 10
1.23 .04 3.64 .12 3.34 .06 5.09 .07 3.98 .26 651 10 .43 .06
•
•
NS
NS NS
NS NS NS NS
NS
NS
NS NS NS NS NS NS NS
.49
.05
• ...
t
= sustained-release.
2FC = Feed conversion, EPC = energetic Pc. 3p > .10.
• p < .05. ••p < .01. tp < .10.
approximately 2 kg/d of milk per cow over all stages of lactation. Feed intake was lower in period 1 and tended to be elevated in later periods for the daily injection and the sustained-release groups. Similarly, EI did not change in the frrst two periods but significantly increased in period 3 (7%) and period 4 (10%) for the daily injection group and in period 4 (13%) for the sustained-release group. Conversely, the FC energetic and FC were decreased (higher efficiency) for the daily injection and the sustained-release groups, especially in earlier periods. Except for energetic FC, no statistically significant differences existed between the daily injection and the sustained-release groups. Least squares means, standard errors, and associated significance for the effect of bST treatment during periods 1 to 4 of lactation on milk composition and BW traits are in Table 5. Except for a significantly lower BW in periods 2 and 3, treatment with sustained-release bST did not affect milk composition, SCC, or BWG. However, treatment with daily injecta-
ble bST significantly (P < .05) increased milk lactose concentrations in periods 2 to 4 and milk protein concentrations in periods 3 and 4. Analysis of Health Variables
Table 6 shows that most health-related variables were not different among treatment groups before, during, or after the 40-wk injection period; however, trends were toward higher incidence of teat and udder disorders and feet and leg problems during the 40-wk injection period in the bST-treated groups than in the control group. The incidence of reproductive problems in control and treated cows is in Table 7. Days open and number of inseminations were used as indices of reproductive efficiency. Least squares means and significance for the effect of bST treatments on these two parameters are in Table 8. Incidence of infections leading to pyometritis or metritis was not different among treatment groups. Similarly, number of services per conception and days open were not Journal of Dairy Science Vol. 75, No. II, 1992
3126
ZHAO ET AL.
affected by bST treatments. However, incidence of GnRH therapy and number of days to first service were higher for cows receiving bST daily injection than for control cows. No differences existed between cows receiving sustained-release and daily injections of bST for any health and reproductive variables monitored.
~ ~~~~~C!i VJ
-
--
DISCUSSION
'"
i~
.S!
II
;E,s 1>
