Morphometric traits increase genetics selection accuracy for body weight in Bali cattle

Bali cattle (Bos javanicus domesticus) are an indigenous genetic resource of Indonesia that exhibit remarkable adaptation to tropical environments. This study aimed to estimate genetic parameters for body weight (BW), withers height (WH), body length (BL) and chest girth (CG) measured at three growth stages: birth (BBW, BWH, BBL and BCG), weaning (WBW, WWH, WBL and WCG) and yearling (YBW, YWH, YBL and YCG). Phenotypic records were collected from 2,180 animals at birth, 796 at weaning and 851 at yearling, recorded between 2017 and 2024 at BPTU-HPT Denpasar. Fixed effects of sex, year of birth (YB), season of birth (SB) and weaning age (WAG) were included in the final model. Heritability estimates increased with age, reflecting shifting genetic control over growth. At birth, heritability values were low for BBW (0.03 ± 0.02), BWH (0.02 ± 0.01), BBL (0.07 ± 0.02) and BCG (0.02 ± 0.01), Heritability estimates were higher at weaning (0.20–0.28) and at yearling age (0.09–0.49) suggesting increasing additive genetic influence with maturation. Genetic correlations between traits measured at the same age were positive and ranged from moderate to strong; 0.56–0.85 at birth, 0.55–0.99 at weaning and 0.69–0.87 at yearling age. Incorporating multiple morphometric traits into selection for increased body weight would increase selection accuracy by 12% at birth, 16% at weaning and 51% at yearling, demonstrating that multi-trait selection enhances early-stage precision and drives long-term genetic improvement in Bali cattle.HIGHLIGHTS This study provides the first comprehensive genetic evaluation of Bali cattle across birth, weaning and yearling stages, with variance components estimated using the Average Information REML (AI-REML) method for multi-trait analyses. Additive genetic effects increased with age. Incorporating multiple traits into selection indices enhanced genetic evaluation accuracy by up to 42.97%, supporting sustainable multi-trait selection strategies for tropical cattle breeding.