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Reproductive Performance Of Crossbred Cows
by Rafique, M | MR. Kazimaraza Chohan | Dr. Muhammad Aleem | Mr. M. Sarwar | Faculty of Veterinary Sciences.
Material type: ; Format:
print
Publisher: 1995Dissertation note: Data on 2290 breeding records of 709 Hoistein-Friesian x Sahiwal (H x S) crossbred cows of various exotic inheritance levels maintained at Livestock Production Research Institute, Bahadurnagar, Okara during 1974-1993 were used in this study. The data were analysed to estimate the magnitude of different reproductive traits, i.e age at maturity, age at first conception, age at first calving, number of services per conception, postpartum oestrus interval, service period, calving interval, dry period, gestation period, conception rate and reproductive efficiency.
The least squares means in various genetic groups of H x S for age at maturity, age at first conception and age at first calving were 618.42 ± 6.78, 697.51 ± 8.03 and 987.85 ± 7.85 days, respectively. The means for postpartum oestrus interval and service period were 95.62 ± 6.66 and 152.43 ± 8.14 days, respectively. The mean for number of services averaged 2.24 ± 0.09. The gestation period was 283.39 ± 0.59 days, whereas the calving interval was 445.43 ± 8.67 days. The mean for dry period was 160.71 ± 7.48 days. The conception rate and reproductive efficiency averaged 53.67 and 82.48 ± 1.42 percent, respectively.
The effect of year of birth on age at maturity, age at first conception and age first calving (H x S) was highly significant (P < 0.01). The effect of genetic group on age at maturity, age at first calving was also highly significant ( P<0.10). The effect of season of birth was significant (P<0.05) for age at maturity, while non-significant results were obtained for age at first conception and age at first calving.
The number of services per conception differed significantly (P<O.O1) due to year of calving, season of calving and genetic groups. The parity had no effect on number of services per conception. The effect of year of calving and season of calving was significant (P<O.O1) for postpartum oestrus interval and service period, while the genetic group had non-significant effect on these parameters. The effect of parity was also significant (P<0.01) for postpartum oestrus interval and service period. The service period was (139.18 ± 9.31 days) in crossbred cows calving during autumn season and longest (162.24 ± 9.78 days) in summer calvers. The postpartum oestrus interval was longest (105.59 ± 7.45 days) in winter calvers and shortest (87.34 ± 7.63 days) in cows calving in autumn season.
The effect of year of calving, season of calving, lactation number (parity) had significant effect (P<0.01) on gestation period and calving interval while the genetic group had no significant effect on' both of these traits. The cows calved during autumn showed shorter (428.94 ± 9.89 days) calving interval as compared to those calved in summer (456.17 ± 10.42 days).
The effect of year of calving, season of calving, parity and genetic groups was significant on dry period. The 1/2 F4 (H x S) cows had minimum (124.40 ± 19.05 days) dry period while 1/4 (H x S) showed the maximum (196.72 ± 14.76 days) dry period.
The effect of season of calving was significant (P< 0.05) on reproductive efficiency while the year of calving and genetic group of the cow had non-significant effect on reproductive efficiency. The cows calved during summer showed lower (78.26 ± 2.02 %) reproductive efficiency while the cows calved in autumn or winter season had higher (84.20 ± 2.37 %) reproductive efficiency.
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