Genetic analysis of pre-weaning litter traits in V-line rabbits using a single-trait animal model

Abstract

The objective of this study was to obtain heritability (h 2 a), permanent environment (pe 2 ) effect, repeatability (R) estimates and predicted breeding values (PBVS) for litter traits which include; litter size at birth (LSB), number of live bunnies at birth (NBA), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW) and litter body gain from birth to weaning (PLG) in V-Line rabbits maintained by the faculty of agriculture, Al-Azhar University in Nasr City, Cairo, Egypt using repeatability single-trait animal model analysis. h 2 a estimates for litter size traits (LSB, NBA, and LSW) were low, ranging from 0.05 to 0.07 and from 0.09 to 0.14 for litter weight traits (LWB, LWW, and PLG). The proportions of pe 2 effect were also small, ranging from 0.0006 to 0.001. Due to the smallness of pe2, the estimated pe 2 was about the same magnitude as for h 2 a. Estimates of genetic correlation (rg) were positive across all correlated traits. It is closely correlated between LSB and NBA and between LWW and PLG (0.99). The rest of rg values, among other traits, were positive, moderate to high, ranging from 0.50 to 0.79. As for rank correlation (rs), it was positive, moderate, and highly significant and ranged from 0.45 to 0.99. Ranges of PBVS for litter size traits revealed that these ranges decreased with the advance of age of the litter from birth up to weaning, and the opposite has been observed for litter weight traits. Based on the results of the current study, this herd needs an environment (non-genetic factors) that is as similar as possible with continuous genetic evaluation and selection based on high breeding animal values.