Revealing the genetic and non-genetic components of variation of survival in farmed White-tailed deer (Odocoileus virginianus, Texanus, Zimmermann, 1780) neonates

Abstract

Recognition and understanding of the factors affecting neonatal fawn survival (FS) is critical for the improvement of management and genetic programs. Data collected from White-tailed deer (Odocoileus virginianus, Texanus) fawns was analyzed to estimate the relative importance of some non-genetic and genetic factors related to FS of captive White-tailed deer (WTD) neonates. Sex of fawn (SX), year (YF) and month (MF) of fawning, litter size (LS), doe service type (ST) and birth weight (BW) were evaluated. FS was analyzed as a linear and quadratic function of BW within LS. Furthermore, a mixed animal model was fitted including the described fixed effects, and the random effects of direct genetic, maternal permanent and residual error. Variance components and heritabilities for FS were estimated. The observed overall survival of neonatal WTD fawns was 85.2%. YF, LS, ST and linear effect of BW had significant effect on FS (P≤0.06). The linear and quadratic effect of BW was significant on FS for singleton and twin fawn LS (P≤0.02), indicating that for these LS an optimum BW exists at fawning, conversely in triplet fawns, BW had a linear negative effect (P=0.07) on LS. Residual variance explained ≈88% of variation of FS. Direct and permanent maternal environmental proportion relative to phenotypic variance estimates were 0.05 and 0.06, respectively. Results highlighted the importance of some non-genetic factors on FS, and their consideration in management systems to improve survival. Estimates of direct heritability and maternal permanent proportion suggested their importance for inclusion into genetic improvement programs of FS in farmed WTD.