Factors affecting weigh-suckle-weigh milk yield estimates and calf performance of zebu cattle

Abstract

One hundred and twentv (120) Sahiwal cows suckling either Sahiwal calves or Friesian x Sahiwal calves and 180 Boran cows suckling Boran calves or Friesian x Baran calves were used in the suckling study. Milk yield and calf weight data were obtained by Weigh-Suclde-Weigh (WSW) method once per week for 36 weeks from 1969 through 1972. Both milk yield/intake and calf performance (average daily gain and weaning weight) were analvsed by a Least Squares Computer Programme (Rege, 1986) for the effect of calf breed, calf sex, season and year of birth on milk vield/intake and growth traits of the calves. The effect of milk production of the dam and of rearing method on growth performance of the calves' were also analysed by the same method. For comparison 130 handfed Sahiwal calves reared in the same vear and 300 handmilked Sahiwal cows were used in growth performance and milk yield estimates, respectively. Total milk yield estimates (1272.35 kg) and calf growth rate per day and weaning weight (0.66 kg and 187 kg respectively) as determined bv the WSW method showed that Sahiwal and Boran cows were quite similar in their milk production therefore were grouped together. Their Friesian cross calves also Berformed similarly in growth rate but Friesian x Sahiwal (FS) calves were slightly superior to Friesian x Boran (FB) calves in weaning weight. Both groups of crossbred calves were 18% heavier than their respective straightbred counterparts in average daLly ga.in. Coefficient of yield determination handmilking (23.75% variation obtained by WSW method for milk was quite similar to that obtained for and 21.84% respectively) indicating comparable accuracy in determining milk yield by the two methods. Correlation between monthly mi lk yield and monthly we ight; gains were highest in the second to fifth months (r=O.53) indicating that monthly tests in the first 5 months would be adequate to assess milk production of the cows and growth performance of suckling calves. Peak milk production by WSW coincided with peak rate of weight gain (in the second month) supporting the use of WSW method for determination of both traits. The effect of calf breed, calf sex, season, year, initial weight of calf, weaning age and milk yield of the dam were highly 'significant for growth traits of the calf while age of dam was not significant. Milk yield of dam was also significantly influenced by calf breed, season, year and initial weight of the calf but not by age of dam and sex of calf.