Genomic Selection Improves Heat Tolerance in Dairy Cattle

Abstract

Dairy products are a key source of valuable proteins and fats for many millions of people worldwide. Dairy cattle are highly susceptible to heat-stress induced decline in milk production, and as the frequency and duration of heat-stress events increases, the long term security of nutrition from dairy products is threatened. Identification of dairy cattle more tolerant of heat stress conditions would be an important progression towards breeding better adapted dairy herds to future climates. Breeding for heat tolerance could be accelerated with genomic selection, using genome wide DNA markers that predict tolerance to heat stress. Here we demonstrate the value of genomic predictions for heat tolerance in cohorts of Holstein cows predicted to be heat tolerant and heat susceptible using controlled-climate chambers simulating a moderate heatwave event. Not only was the heat challenge stimulated decline in milk production less in cows genomically predicted to be heat-tolerant, physiological indicators such as rectal and intra-vaginal temperatures had reduced increases over the 4 day heat challenge. This demonstrates that genomic selection for heat tolerance in dairy cattle is a step towards securing a valuable source of nutrition and improving animal welfare facing a future with predicted increases in heat stress events.

Heat Stress in Dairy Cattle Alters Lipid Composition of Milk

“…5 in this same experiment, which led to suppressed ruminal fermentation and consequently reduced supply of acetate and butyrate. However, diminished anabolic activities including synthesis of fatty acids in mammary gland due to partitioning of energy in thermoregulation-related processes in response to heat stress may also be responsible 1, 4 .…”

“…In addition to the monitoring of milk yield, dry matter intake, respiration rate and body temperature, these authors also determined the milk composition (lactose, protein and fat %) using infrared-based technique 5 . As part of a collaborative project, an aliquot of milk samples from the same experiment was brought to our laboratory and subjected to detailed lipid composition analysis.…”

Powerful detection of polygenic selection and evidence of environmental adaptation in US beef cattle

“…While all four of the Red Angus genes were identified in multivariate analyses, we identify two of them in the Desert ecoregion univariate envGWAS. Vasodilation is an essential component of physiological temperature adaptation in cattle and other species [164][165][166] . The ability to mount a physiological response to heat stress has a direct impact on cattle performance.…”

Efeito do sistema de criação no desempenho técnico e econômico de rebanhos leiteiros

“…In PB systems, dry matter ingestion is the main limiting factor (BARGO et al, 2002) and animals expend more energy grazing (AGNEW; YAN, 2000), in addition to the lower energetic efficiency due to higher methane production, when compared with animals fed with higher concentrate-content diets (LANA; RUSSUELL, 2001). Furthermore, because the grazing cows spend the majority of their time exposed to solar radiation and do not benefit from fans and sprinklers -common to freestall structures -they are more susceptible to heat stress effects (COLLIER et al, 2006;GARNER et al, 2016), although crossbred cows commonly used in pasture-based systems are more adapted to heat (COSTA et al, 2015). Values obtained in this study were higher than the average production in the State of Minas Gerais [2,956.5 L (FAEMG, 2006)] and lower than those reported by Silva et al (2006) for the State of Paraná (between 5,829.1 and 10,201.8 L).…”