GM 02. Comparison of two genetic classes of holstein sires crossed with zebus in dual purpose herds

• Lucia Vaccaro ^[1] ; Rodolfo Vaccaro ^[1] ; Omar Verde ^[1] ; A. Perez ^[1] ; H. Mejias ; R. Khalil ^[1]
  1. [1] Universidad Central de Venezuela

     Universidad Central de Venezuela

     Venezuela

     
• Localización: Archivos Latinoamericanos de Producción Animal, ISSN 1022-1301, ISSN-e 1022-1301, Vol. 5, Nº. Extra 3, 1997 (Ejemplar dedicado a: Proceedings XV ALPA meeting 2)
• Idioma: inglés
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• Resumen

  • The zebu crossbred progeny of 41 USA Holstein sires were evaluated on seven Venezuelan farms. Bulls were grouped into high (H) and medium (M) classes, according to their USA milk proofs which averaged 237 kg (M) and 934 kg (H), with mean repeatabilities of 97% and 98%. From 1256 zebu cows inseminated in 1990-95, 736 calves were born alive. Records included pregnancy and birth rates; losses of both sexes from birth to 4, 8 and 18 months; and weight for age of both sexes to 4, 8, and 18 months, as well as to final weight (427 kg). Information was also available on the age at first calving, first lactation milk yield, interval from calving to conception and 4-month calf weight of 118 female progeny on four farms. Pregnancy, birth and mortality rates were compared between sire classes using adjusted chi-squared and the rest of the data were analysed using linear models including sire class (C), farm (F), sex, year and season of birth/calving, and F x C. The difference in death rate to 4 months of age (13.9%, M; 21.2%, H) of progeny reared with restricted suckling was significant at the P