A systematic review of non-productivity-related animal-based indicators of heat stress resilience in dairy cattle

Abstract Background The effect of heat stress on livestock production is a worldwide issue. Animal performance is influenced by exposure to harsh environmental conditions potentially causing genotype-by-environment interactions (G × E), especially in highproducing animals. In this context, the main objectives of this study were to (1) detect the time periods in which heifer fertility traits are more sensitive to the exposure to high environmental temperature and/or humidity, (2) investigate G × E due to heat stress in heifer fertility traits, and, (3) identify genomic regions associated with heifer fertility and heat tolerance in Holstein cattle. Results Phenotypic records for three heifer fertility traits (i.e., age at first calving, interval from first to last service, and conception rate at the first service) were collected, from 2005 to 2018, for 56,998 Holstein heifers raised in 15 herds in the Beijing area (China). By integrating environmental data, including hourly air temperature and relative humidity, the critical periods in which the heifers are more sensitive to heat stress were located in more than 30 days before the first service for age at first calving and interval from first to last service, or 10 days before and less than 60 days after the first service for conception rate. Using reaction norm models, significant G × E was detected for all three traits regarding both environmental gradients, proportion of days exceeding heat threshold, and minimum temperature-humidity index. Through single-step genome-wide association studies, PLAG1, AMHR2, SP1, KRT8, KRT18, MLH1, and EOMES were suggested as candidate genes for heifer fertility. The genes HCRTR1, AGRP, PC, and GUCY1B1 are strong candidates for association with heat tolerance. Conclusions The critical periods in which the reproductive performance of heifers is more sensitive to heat stress are trait-dependent. Thus, detailed analysis should be conducted to determine this particular period for other fertility traits. The considerable magnitude of G × E and sire re-ranking indicates the necessity to consider G × E in dairy cattle breeding schemes. This will enable selection of more heat-tolerant animals with high reproductive efficiency under harsh climatic conditions. Lastly, the candidate genes identified to be linked with response to heat stress provide a better understanding of the underlying biological mechanisms of heat tolerance in dairy cattle.

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PSVII-6 Effects of heat stress on proteolysis in dairy cattle skeletal muscle

Journal of Animal Science ◽

10.1093/jas/skaa054.298 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 168-168

Author(s):

Melissa S Roths ◽

Megan A Abeyta ◽

Tori Rudolph ◽

Brittany Wilson ◽

Matthew B Hudson ◽

...

Keyword(s):

Skeletal Muscle ◽

Heat Stress ◽

Dairy Cattle ◽

Electric Heating ◽

Economic Loss ◽

Urea Nitrogen ◽

Plasma Urea ◽

E3 Ligases ◽

Acclimation Period ◽

Milk Urea

Abstract Heat stress (HS) occurs when internal body temperatures are elevated above a thermoneutral zone in response to extreme environmental temperatures. In the U.S. dairy industry, HS results in economic loss due to decreased feed intake, milk quality, and milk yield. Previous work has demonstrated increased plasma urea nitrogen in heat stressed dairy cattle which is thought to originate from increased skeletal muscle proteolysis, however this has not been empirically established. The objective of this investigation was to determine the extent to which HS promotes proteolysis in skeletal muscle of dairy cattle. We hypothesized HS would increase activation of the calpain and proteasome systems in skeletal muscle. To test this hypothesis, following a 3-d acclimation period in individual box stalls, all lactating dairy cows were held under thermoneutral (TN) conditions for 4-d for collection of baseline measures and then exposed to TN or HS conditions for 7-d followed by a biopsy of semitendinosus (n=8/group). To induce HS, cattle were fitted with electric heating blankets, which they wore for the duration of the heating period. This approach increased rectal temperature 1.1°C (P< 0.05), respiratory rate by 33 bpm (P< 0.05), plasma urea nitrogen by 19% (P=0.08) and milk urea nitrogen by 26% (P< 0.05), and decreased dry matter intake by 32% (P< 0.05) and milk production by 26% (P< 0.05) confirming HS. Contrary to our expectations, we discovered that calpain I and II abundance and activation, and calpain activity were similar between groups. Likewise, protein expression of E3 ligases, MafBx and Murf1, were similar between groups as was total ubiquitinated proteins and proteasome activity. Collectively, and counter to our hypothesis, these results suggest skeletal muscle proteolysis is not increased following 7-d of HS. These data question the presumed dogma that increased blood urea nitrogen is due to elevated proteolysis in skeletal muscle.

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The differences in heat stress resistance due to dairy cattle breed

Mljekarstvo ◽

10.15567/mljekarstvo.2017.0203 ◽

2017 ◽

pp. 112-122 ◽

Cited By ~ 2

Author(s):

Vesna Gantner

Keyword(s):

Heat Stress ◽

Dairy Cattle ◽

Stress Resistance ◽

Cattle Breed ◽

Heat Stress Resistance

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The Mechanism Underlying the Balance Between Heat Stress Resilience and Vulnerability are Mediated by Dna Methylation and De-Methylation at a Regulatory Segment of the Dna Encoding Corticotrophin-Releasing-Hormone

European Neuropsychopharmacology ◽

10.1016/j.euroneuro.2016.09.615 ◽

2017 ◽

Vol 27 ◽

pp. S508

Author(s):

Tomer Cramer ◽

Tali Rosenberg ◽

Tania Kisliouk ◽

Noam Meiri

Keyword(s):

Dna Methylation ◽

Heat Stress ◽

Dna Encoding ◽

Stress Resilience ◽

Releasing Hormone

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A review of intervention methods used to reduce flying-fox mortalities in heat stress events

Australian Mammalogy ◽

10.1071/am20038 ◽

2021 ◽

Vol 43 (2) ◽

pp. 137

Author(s):

Matthew Mo ◽

Mike Roache

Keyword(s):

Climate Change ◽

Systematic Review ◽

Heat Stress ◽

Evidence Based ◽

Evaporative Heat Loss ◽

Temperature And Humidity ◽

Intervention Trials ◽

Individual Scale ◽

The Relationship ◽

Flying Fox

Heat stress events in Australian flying-fox camps have resulted in significant numbers of flying-fox deaths. The frequency and intensity of such events have increased in recent decades, attributed to anthropogenic climate change. Evidence-based interventions are required to address this growing threat. Responders currently use different combinations of a range of intervention methods. We undertook a systematic review of heat stress interventions, which we classified as either ‘camp-scale’ or ‘individual-scale’. Camp-scale interventions included manual and automated misting of roost vegetation, whereas individual-scale interventions included spraying individual animals or removing them for intensive cooling and rehydration procedures. Our study showed that to date, evaluation of the efficacy of heat stress interventions has been largely anecdotal rather than empirical. This highlights the need for dedicated rigorous studies to evaluate the effectiveness of all the intervention methods described here. It will be especially important to understand the relationship between camp temperature and humidity levels and their influence on flying-foxes’ ability to regulate their body temperature, because high relative humidity reduces the ability of mammals to cool themselves using evaporative heat loss. The development of biophysiological measures such as temperature and humidity indices for different flying-fox species would enable meaningful interpretations of intervention trials under controlled conditions.

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