Influence of milk production of Guzerá and Swiss-Guzera cows on preweaning performance of their progenies
Abstract
The milk yield of 45 guzera dams and 59 brown-swiss x guzera (F1) were evaluated in order to verify its influence on growth characteristics of their crossbred calves. The experiment was conducted at the Estação Experimental de Zootecnia de Andradina, State of São Paulo, Brazil, in 1977 and 1978. The milk yield of the cows (L) and the calves characteristics (weights - P and average daily gains - G) were all divided in three periods:I from birth to 4 months (L4; P4; G4), II. from 4 to 7 months which was the weaning age (L7; G7) and III. from birth to weaning (LD; PD; GD). The daily milk yield was obtained by hand milking after an injection of oxytocin (25 I.U./cow) and after allowing the cows to become aparted of their calves for 18/20 hours. The statistical analyses utilizing linear models considered the milk yield (L) as a dependent variable and as a continous independent variable besides the effects of breed of dam, crossbred groups within breed of cow, year, month of birth and sex of the calf. The results showed that the influence of milk was higher until 4 months of age. For each additional kilogram of milk produced by the cow there was an increase of 2.8kg (P <0.05) and 25.6g/day (P<0.01) in P4 and G4 respectively. The averages for P4, G4 and L4 were respectively 124 ± 22kg, 768± 152g/day and 5.582 ± 1.960g. The analyses that considered the data provided by both groups of dams did not show any significant effect of their milk yield from birth to weaning (LD) on the growth characteristics of their calves (1€™ >0.05). On the other hand, within the breed of dam analyses showed that for guzera cows (GG), which presented lower milk yield, the LD was very important. For each addicional kilogram of milk produced by GG cows there was an increase of 14.8kg (P <005) of PD. Among several other factors, the breed of the cow was the most important one to cause differences on milk yield (L). The SG cows had higher milk yield when compared to the GG (P <0.01) being the average values 6.940 ± 1.359 vs. 3.719 ± 1 .473g for L4,6.138± 1 .404vs.3160 ± L518gfor L7and 6.484 ± 1.198 vs. 3.469 ± 1.287g for LD.Downloads
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