Providing artificial shade in relatively treeless rangelands to increase calf survival

Abstract

Foetal and calf losses between confirmed pregnancy and weaning, also known as calf wastage, have been identified as a significant issue by beef producers in Northern Australia. A study of the reproductive performance of 142 commercially managed breeding mobs in the region by McCosker et al. (2022) found that 25% of mobs in the Northern Downs had foetal and calf losses exceeding 15%. According to Beef CRC studies, pre-natal loss in the absence of infectious disease averages only around 3%, with most loss, which constitutes approximately two-thirds of all postnatal losses, occurring within the first week of life (Bunter et al. 2014). Heat stress is a potential factor that contributes to calf loss, and in the Northern Downs, a 7% higher occurrence of calf loss was observed for heifers in the region when the temperature humidity index exceeded 79 for at least two weeks during the month of expected calving (Fordyce et al., 2022). Modifying the environment can reduce heat gain and elevate heat dissipation to protect calves and heifers from heat stress. The Northern Territory Department of Industry, Tourism, and Trade collaborated with researchers from the University of Queensland and the University of Southern Queensland to evaluate the effectiveness of providing paddock-shade shelters in reducing the occurrence of calf wastage. Although the provision of artificial shade to open grazing lands has the potential to improve animal welfare, it did not appear to be an effective method of consistently reducing the occurrence of foetal and calf loss, nor did it lead to any other production gains.