Genetic parameters for liveweights of beef cattle in the tropics

Abstract

This paper describes a genetic analysis of 20000 weighings from 1980-1988 on the progeny of more than 210 sires from three straightbred Brahman and one crossbred herd (Brahman or SahiwalxBritish breeds) in the Australian tropics. 200 day weight averaged 192 kg, very slightly less than 200 day weight in temperate Australia with similar phenotypic variance of 520 kg2. Mean 550, 700, and 900 day weights of 310, 350 and 450 kg and phenotypic variances of 800, 800 and 1485 kg2 were lower than in temperate regions at the same ages. Direct heritabilities for weight averaged 41% in the Brahmans and 31% in the crossbred herd. Genetic correlations amongst 200 day and later weights were 81-92%, except for an estimate of 63% between 200 and 900 day weights. Estimates of heritabilities for maternal effects were quite high in the crossbred herd for 200 and 365 day weights (19 and 14%), but only 4-5% for Brahmans. Models and statistical analyses are discussed and results compared with other published estimates from subtropical and temperate regions.