Voluntary solar radiation exposure and vaginal temperature in slick-haired purebred Senepol and Senepol x Red Angus crossbred heifers

Abstract

Senepol is a slick-haired Bos taurus breed highly adapted to tropical countries, and their meat is usually low in intramuscular fat. Crossbreeding with breeds more suited to higher marbling scores (e.g., Angus; a wild type-haired breed) may help improve this meat quality trait. However, the question of adaptability to tropical weather in the resulting crossbreeds remains. This study compared the voluntary exposition to direct solar radiation or shade and the vaginal temperatures of slick-haired 50% Senepol - 50% Red Angus (n=5; 50:50), 75% Senepol - 25% Red Angus (n=5; 75:25), and 100% Senepol (n=5; 100:0) heifers in February 2023. Data were analyzed by the GLIMMIX procedure (SAS). The 50:50 heifers recorded lower solar radiation exposure than their 75:25 and 100:0 counterparts at 1100 (P≤0.001), 1115 (P≤0.0003), 1130 (P<0.0001), 1145 (P≤0.004), and 1200 h (P≤0.004). Respective average values of 20,601.40±3,615.03; 32,627.40±4,437.84; and 32,260.40±4,424.65 lx were observed during this period. No differences in vaginal temperature were observed between heifer groups (P=0.8135), with daily averages of 37.27±0.54, 37.23±0.53, and 37.23±0.54 °C for the 50:50, 75:25, and 100:0 heifers, respectively. Heifers with 50% Red Angus blood needed to spend more time under shade during the hottest hours of the day to maintain a body temperature similar to those heifers with greater Senepol influence.