Location: Livestock and Range Research LaboratoryTitle: Impact of cold stress on birth and weaning weight in a composite beef cattle breed
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2020
Publication Date: 6/1/2020
Citation: Toghiani, S., Hay, E.A., Roberts, A., Rekaya, R. 2020. Impact of cold stress on birth and weaning weight in a composite beef cattle breed. Livestock Science. 236:104053. https://doi.org/10.1016/j.livsci.2020.104053.
Interpretive Summary: In the Northern Great Plains, beef cattle are exposed to long and cold winters leading to cold stress on the animals. This stress reduces the performance of animals and the overall productivity. The objective of the study is to investigate the genetic basis of cold stress and to evaluate its effect on the growth of claves in a composite beef cattle breed. The results have shown that mild and moderate cold stress had a positive effect on birth weight whereas the impact of severe cold stress had a negative effect on birth weight. However, all mild, moderate, and severe conditions of cold stress had a negative effect on calves weaning weights which could be due to a reduction of milk production from cows, negative effect of pre-calving cold stress on pasture conditions, or epigenetic mechanism during fetal stage. Variation in the effect of cold stress across paternal half-sib families for both birth and weaning weight supported the likelihood for a potential genetic basis of cold stress response.
Technical Abstract: Beef cattle are often exposed to extreme environmental conditions with varying temperatures, humidity, wind speed and solar radiation. The objective of this study was to investigate the impact of cold stress on growth-related traits and to assess its variation between sire families in a composite beef cattle breed in eastern Montana. Weather data were collected from an airport near the research station. Comprehensive climate index (CCI), a measure of cold load, was used to classify cold stress into mild (CCI < -5), moderate (CCI < -15), and severe (CCI < -25). The phenotypic data consisted of 4,221 and 4,217 records for birth weight (BWT) and weaning weight (WWT), respectively. For both traits, the statistical model included an overall mean, contemporary groups, and a regression on cold stress load. For WWT, the model included additional regressions on birth weight and age at weaning. The results showed that mild and moderate cold stress increased BWT by 5.88 and 0.71 kg, respectively. However, severe cold stress slightly decreased BWT (-0.010 kg). Cold stress resulted in a significant decrease in WWT for mild (27.90 kg) and monderate (17.42 kg) cold stress, while the decrease in WWT for severe (2.07 kg) cold stress was insignificant. Using only data from the three different sire families with the largest paternal half-sib familes, estimates of within family regression coefficients on cold stress were statistically different (based on Welch’s t-test) for BWT and WWT. These results seem to indicate that cold stress has limited negative (often positive) effect on BWT which could be due to some nutritional prioritization of nutritional resources toward the fetus. Furthermore, comparing cold stress effects across different sire families indicated the existence of potential genetic variation in cold stress response.