BRIEF COMMUNICATION: Influence of the ‘SLICK’ allele of the prolactin receptor gene (PRLR) on the growth and behaviour of dairy heifers during winter

Abstract

This study investigated the effects of the SLICK allele on the responses of dairy heifers in cold conditions in New Zealand. Three groups (n=9/group), control, non-SLICK and SLICK progeny of bulls heterozygous for the SLICK allele were investigated. These heifers were grazed together to identify their responses to winter conditions under adequate, followed by restricted feed allocation. The control group had an 87% lower growth rate during the restricted period compared to the SLICK group (0.064 vs 0.484 kg/d, P = 0.035). During restricted feeding conditions, the SLICK heifers showed improved pasture harvesting efficiency, by maintaining growth rate while having a lower eating time, compared to the control heifers (277 vs 317 ± 10.9 mins/day respectively, P = 0.017). The SLICK group were also less active than the control group. These differences indicate more research is needed to understand the wider role of the prolactin axis on the physiological responses of SLICK cattle.