The effects of fasting and transportation on beef cattle. 1. Acid-base-electrolyte balance and infrared heat loss of beef cattle

Abstract

The purpose of the present study was to examine acid—base—electrolyte and thermal adaptation in beef cattle subjected to marketing stress. Fifty yearling, market-weight Hereford steers and heifers were allocated to one of 3 treatments. Treatment 1 (T1, n = 17) animals were transported 3 km and slaughtered following a 24-h fast. Treatment 2 animals (T2, n = 17) were mixed by sex, transported 320 km and slaughtered after a 48-h fast. Treatment 3 animals (T3, n = 16) were transported as per T2 with an additional 320 km transport on Day 2 (total fasting = 72 h) prior to slaughter. Compared to pretreatment measurements, blood bicarbonate, base excess, carbon dioxide and hydrogen-ion concentration were reduced ( P < 0.01) for all animals when measured again immediately preslaughter. In contrast, blood lactate was seen to increase ( P < 0.04) compared with preslaughter values. Among treatments, T2 animals displayed higher ( P ⩽ 0.05) bicarbonate, base excess and standard bicarbonate values than animals in T1 or T3. The mean infrared body heat loss was reduced ( P ⩽ 0.01) with increased fasting and transportation which, interestingly, coincided with progressively darker meat colour. These data suggest marketing stress can induce changes in the acid-base and thermodynamic status of an animal.