SOME FACTORS AFFECTING ON TWINNING RATE AND ITS EFFECTS ON POSTPARTUM REPRODUCTIVE PERFORMANCE AND OF FRIESIAN COWS

Sh.M. Shamiah, A.A.  Shitta and H.M.A. Gaafar

Animal Production Research Institute, Agricultural Research Center, Dokki, Giza, Egypt

SUMMARY

A total number of 1243 calving cases of 585 dairy Friesian cows during 8 consecutive years from 1997 to 2004 were used to study the effect of sire, live body weight (LBW) and age of dam, parity, calving season and feeding system on twinning rate and its consequent effects on postpartum reproductive performance, incidence of reproductive disorders and milk yield of dairy cows.

Results indicated that, the average of twinning rate was 4.67% and freemartin rate was 0.64%. Sire, live body weight and age of dam, parity, calving year, calving season and feeding system had significant (P<0.05) effects on twinning rate. Twinning rate increased significantly (P<0.05) with increasing LBW and age of dams as well as with advancing of parity from 1st up to the 6th parity and decreased afterwards. Winter season significantly showed the lowest (P<0.05) twinning rate (3.76%) and autumn season had the highest rate (6.20%). The twinning rate was significantly lower (P<0.05) with winter feeding as compared to summer feeding.

Twins calving affected significantly (P<0.05) all the reproductive performance under consideration except the period from calving to first service and gestation period. In this respect, the service period, days open and calving interval were longer, number of service per conception was higher, while conception rate was lower for twins compared with single calving. The percentages of retained placenta, dystocia, abortion and born death calf were significantly (P<0.05) higher with twins calving compared to single calving. Lactation period and total milk yield was higher significantly (P<0.05), while daily milk yield tended to be higher for cows birth twins compared with those birth single.

These results indicated that, several factors (genetic and environmental) affected on twinning rate in dairy Friesian cows. Calving interval for cows calved single or twins was in rate accepted, while retained placenta, dystocia, abortion and born death calf were nearly duplicate in cows calved twins compared to that of single calving.

Keywords: Friesian cows, twins calving, reproductive performance.

INTRODUCTION

Typically, dairy cattle breeders consider twins calving to be detrimental. Twinning has many negative effects on some reproductive and productive aspects including increased dystocia, retained placenta, longer rebreeding intervals, higher mortality rates, frequent occurrence of freemartins (sterile females) (Beerepoot et al., 1992; Nielen et al., 1989) and reduced and (or) delayed conception after twinning (Turman et al., 1971; Gregory et al., 1990b). One would anticipate a preference for selection against twinning. However, individuals with high twinning rates still appear, especially in the Holstein breed, which ranged from 1.6 to 8.8% (Rutledge, 1975). Day et al. (1995) reported that California Holstein cows gave 6.86% of birth twins. Eddy et al. (1991) observed twinning rate in British dairy cattle was 2.5% and increased with parity (0.9% for first parity up to 5% by sixth parity). Nielen et al. (1989) observed a 3.2% twinning rate in Dutch Friesians and Holsteins. Protection of recessive alleles may explain the repeated occurrence of high twinning individuals. However, Van Vleck and Gregory (1996) reported no dominance effects for ovulation rate, a trait closely related to twinning rate. Gregory et al. (1990) concluded that twinning rate is a quantitative trait that has an underlying continuous expression involving many loci.

Although repeatability was not estimated, Nielen et al. (1989) noted a tendency of twinning cows to twins again from cows that had twinned once and twice, 9.3 and 12.5%, respectively. It should be noted that these values were higher than expected. Assuming that 6.4 and 3.3% from cows twinned once and twice would be expected to twins again. Ron et al. (1990) reported the twinning rate in Israeli Holsteins to be 4.8 and 6.9% for second and third parity cows, respectively. The twinning rate of Israeli Holsteins has increased from 4.5 to 5.6% during the last 20 year. In general, twinning reduced the reproductive performance of dams in their subsequent pregnancy and in the case of freemartins reduced the calves’ reproductive performance as well (Beerepoot et al., 1992; Eddy et al., 1991).

The objective of this study was to evaluate the effect of sire, live body weight and age of dams, parity, calving season and feeding system on twinning rate and its effects on reproductive problems and postpartum reproductive and productive performance of dairy Friesian cows.