Relation between Holstein bulls’ proofs for milk in USA and the milk yield, age at first calving, calving interval and survival to third calving of their F₁ zebu progeny in Venezuela

Abstract

Summary To determine the effect of USA Holstein bulls’ breeding value for milk yield on the performance of their female F1 progeny in the lowland tropics of Venezuela, semen was chosen from 39 sires, representing bulls with the highest (class H, n = 21) or average (class A, n = 18) proofs for milk, available locally. The mean proofs of the H and A sires were 937 and 237 kg milk, respectively, when semen was purchased in 1989–93, and 212 and −386 kg when updated in 2001. Progeny from commercial zebu dams were kept grazing on three dual purpose farms, where herd average milk yields were 735, 1113 and 3524 kg per lactation. Records on milk yield, lactation length, calving interval, age at first calving and survival rate to first, second and third calving from 222 progeny (476 lactations) were analysed using mixed linear models. The effect of sire class approached significance (p = 0.07) for milk yield and survival rate to second calving, with H daughters superior to A progeny by 41 and 46%, respectively, and no significant disadvantage for any trait. Class × farm interaction was only significant for age at first calving. Rank correlations using USA proofs for milk and the adjusted mean values for bulls with =15 F1 records were 0.72 (p < 0.01, milk yield) and −0.07 (calving interval). Differences between sires, within classes, were highly significant for age at first calving and calving interval. It was concluded that the use of Holstein bulls with high USA milk proofs is probably justified for producing F1 daughters, but that evaluation for growth rate and daughter fertility under tropical grazing conditions may be advisable.

Relation between Holstein bulls’ proofs for milk in USA and the survival and body weights up to 18 months of their F1 zebu progeny in Venezuela

“…At 18 months, the only significant difference between groups was also in favour of the H progeny. These results are compatible with the trend towards higher survival rates among H daughters up to second calving (V accaro et al. 2003).…”

“…1986, 1990), but there seems to be no other evidence that this superiority may also be manifest in crossbred progeny, or under lowland tropical grazing conditions. However, it is of note that the advantage found for the H progeny in 18‐month weight was not reflected in any difference due to sire class in the age at first calving (V accaro et al. 2003).…”

“…The objective of the present paper is to describe the relationship between the breeding value of Holstein bulls for milk yield in the USA and the body weights and survival to 18 months of age of their F 1 zebu progeny under lowland tropical grazing conditions. The milking performance of the F 1 females is described in a companion paper (V accaro et al. 2003).…”

Desempenho produtivo e reprodutivo de fêmeas F1 Holandês x Nelogir

“…Esses autores explicaram que a falta de avaliações genéticas adequadas e o tamanho da amostra (30 vacas filhas de touros "leiteiros" e 50 "não leiteiros") influenciaram os resultados. Vaccaro et al (2003) estudaram o efeito do uso de touros Holandês de valor genético variando de superior a médio, provados nos EEUU, no desempenho de suas filhas F1, na Venezuela. Os autores observaram que as filhas dos touros com valor genético superior produziram, em média, 41% a mais de leite do que aquelas filhas dos touros com valor genético médio.…”

“…Os autores observaram que as filhas dos touros com valor genético superior produziram, em média, 41% a mais de leite do que aquelas filhas dos touros com valor genético médio. Desse modo, o uso de touro Holandês de comprovado valor genético justifica-se como alternativa para cruzamento com vacas zebuínas para produção de fêmeas F1 (VACCARO et al 2003). Considerando o avô materno da raça Gir, não se observou diferença significativa para produção de leite total dentro das classificações superior, inferior e sem prova, independentemente do PTA do touro Holandês (Tabela 4).…”