Abstract

The heat tolerance of Senepol beef cattle (Bos taurus) has been causally linked to a mutation in the prolactin receptor (PRLR) on BTA20. This variant of PRLR has become known as the SLICK gene because it is also associated with a short-hair coat. We have investigated the heat tolerance of New Zealand dairy cattle bred to carry the SLICK gene, using measurement of vaginal temperature. Hair length differed (P<0.001) between SLICKs and controls at the neck (4.3 ± 0.5 mm vs 13.8 ± 1.2 mm, respectively), shoulder (6.5 ± 0.7 mm vs 14.9 ± 1.5 mm, respectively) and pin bone (6.9 ± 0.6 mm vs 15,2 ±1.4 mm, respectively). Vaginal temperatures of SLICK animals were 0.5 - 1°C lower than controls at peak ambient temperature (28.4°C; 16.00h). SLICK dairy cattle show a markedly improved ability for temperature homeostasis under mild heat load, relative to control cattle. Keywords: heat tolerance; dairy cattle; SLICK; genetics

Worth, GM, Donkersloot EG, Spelman RJ, and Davis SR

New Zealand Journal of Animal Science and Production, Volume 83, Rotorua, 5-7, 2023