Genetic Parameters for Maternal Performance Traits in Commercially Farmed New Zealand Beef Cattle.

Maternal performance is a major driver of profitability in cow-calf beef cattle enterprises. The aim of this research was to evaluate the inheritance of maternal performance traits and examine the intercorrelation among reproduction, live weight, hip height, body condition and maternal contribution to calf weaning weight in 15-month-old heifers, 2-year-old cows and mature cows in New Zealand beef herds. Data were collected on a total of 14,241 cows and their progeny on five commercial New Zealand hill country farms. Heritabilities were low for reproductive traits in heifers and mature cows (0-0.06) but were greater in 2-year-old cows (0.12-0.21). Body condition scores were lowly (0.15-0.26) and live weights (0.42-0.48) and hip heights (0.47-0.65) highly heritable in heifers, 2-year-old cows and mature cows. Results indicate that 2-year-old cows with higher genetic potential for rebreeding ability may have greater genetic merit for live weight, hip height and body condition as heifers (r = 0.19-0.54) but are unlikely to be larger cows at maturity (r = -0.27--0.10). The maternal genetic effect on weaning weight had a heritability of 0.20 and was negatively genetically correlated with body condition score in lactating cows (r = -0.55--0.40) but positively genetically correlated with rebreeding performance (r = 0.48).