Genes and models for estimating genetic parameters for heat tolerance in dairy cattle

Abstract

Dairy cattle are highly susceptible to heat stress. Heat stress causes a decline in milk yield, reduced dry matter intake, reduced fertility rates, and alteration of physiological traits (e.g., respiration rate, rectal temperature, heart rates, pulse rates, panting score, sweating rates, and drooling score) and other biomarkers (oxidative heat stress biomarkers and stress response genes). Considering the significant effect of global warming on dairy cattle farming, coupled with the aim to reduce income losses of dairy cattle farmers and improve production under hot environment, there is a need to develop heat tolerant dairy cattle that can grow, reproduce and produce milk reasonably under the changing global climate and increasing temperature. The identification of heat tolerant dairy cattle is an alternative strategy for breeding thermotolerant dairy cattle for changing climatic conditions. This review synthesizes information pertaining to quantitative genetic models that have been applied to estimate genetic parameters for heat tolerance and relationship between measures of heat tolerance and production and reproductive performance traits in dairy cattle. Moreover, the review identified the genes that have been shown to influence heat tolerance in dairy cattle and evaluated the possibility of using them in genomic selection programmes. Combining genomics information with environmental, physiological, and production parameters information is a crucial strategy to understand the mechanisms of heat tolerance while breeding heat tolerant dairy cattle adapted to future climatic conditions. Thus, selection for thermotolerant dairy cattle is feasible.

Utility of indirect phenotype measurement system on genomic prediction in Japanese Black cattle: a simulation study using public data

“…In dairy cattle, the association between fatty acid composition of milk and reproductive performance has been investigated (e.g., Bastin et al 2012;Mehtiö et al 2020;Martinez-Castillero et al 2021). Smart breeding technology has been developing in livestock production (e.g., Gorssen et al 2022;Habimana et al 2023;Manzanilla-Pech et al 2023), which might lead to an increase in novel candidate traits. Meanwhile, concern about the decline in genetic diversity in the Japanese Black cattle population has been growing (Nomura et al 2001).…”

Heat stress effects on milk yield traits and metabolites and mitigation strategies for dairy cattle breeds reared in tropical and sub-tropical countries

“…Additionally, the THI which combines the effects of ambient temperature and relative humidity, wind speed and solar radiation is also a proxy for HS conditions, and may approximate potential HS in dairy cattle. A comprehensive review about those HS biomarkers was presented in our previous review (45). Table 2 shows indicators of HS in dairy cattle and methods used to measure them.…”

“…Heat stress prevents dairy cattle to fully express their genetic potentials for milk yield and affects milk composition (63). Dairy cattle react to HS through: (1) decline in feed intake, (2) high water consumption, (3) altered basal metabolic rate, (4) increased evaporation of water, (5) physiological changes, i.e., higher body temperature, higher respiratory rate, panting rate, pulse rate, heart rate, rectal temperature, and ( 6) altered blood hormone concentration (45). A dairy cow experiencing HS produces small quantity of milk and has a high risk of disease infection (61).…”

“…The statistical models used in the genetic evaluation studies applying test-day milk production records include (1) repeatability models which consider equal genetic relationship between every test-day milk records, (2) single trait and multiple traits models applying every test-day milk record as different parameters, and (3) random regression models (RRM) which treat a covariate function of repeated test-day milk records overtime (97). A more detailed description about these models was made in our previous review (45). The RRM have the potential to analyze every test-day milk records assuming that genetic and non-genetic variances change with days in milk (DIM), parity, lactation stage as do genetic and non-genetic relationships (97).…”

Innovations in Dairy Cattle Management: Enhancing Productivity and Environmental Sustainability

“…As global temperatures continue to rise due to climate change, heat tolerance has surged in significance. Habimana et al (2023) elucidated the necessity of integrating genomic information with environmental and physiological parameters to breed heat-tolerant dairy cattle capable of thriving in future climatic conditions [8]. Genetic evaluation and selection for thermotolerant traits have emerged as cornerstones in fortifying the resilience of dairy cattle in challenging environments.…”