Geographical influence of heat stress on milk production of Holstein dairy cattle on pasture in South Africa under current and future climatic conditions

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.

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Glucose Metabolism and Dynamics of Facilitative Glucose Transporters (GLUTs) under the Influence of Heat Stress in Dairy Cattle

Metabolites ◽

10.3390/metabo10080312 ◽

2020 ◽

Vol 10 (8) ◽

pp. 312 ◽

Cited By ~ 1

Author(s):

Zaheer Abbas ◽

Abdul Sammad ◽

Lirong Hu ◽

Hao Fang ◽

Qing Xu ◽

...

Keyword(s):

Heat Stress ◽

Glucose Metabolism ◽

Dairy Cattle ◽

Milk Production ◽

Molecular Mechanisms ◽

Glucose Transporters ◽

The Body ◽

Whole Body ◽

Negative Consequences ◽

Energetic Metabolism

Heat stress is one of the main threats to dairy cow production; in order to resist heat stress, the animal exhibits a variety of physiological and hormonal responses driven by complex molecular mechanisms. Heat-stressed cows have high insulin activity, decreased non-esterified fatty acids, and increased glucose disposal. Glucose, as one of the important biochemical components of the energetic metabolism, is affected at multiple levels by the reciprocal changes in hormonal secretion and adipose metabolism under the influence of heat stress in dairy cattle. Therefore, alterations in glucose metabolism have negative consequences for the animal’s health, production, and reproduction under heat stress. Lactose is a major sugar of milk which is affected by the reshuffle of the whole-body energetic metabolism during heat stress, contributing towards milk production losses. Glucose homeostasis is maintained in the body by one of the glucose transporters’ family called facilitative glucose transporters (GLUTs encoded by SLC2A genes). Besides the glucose level, the GLUTs expression level is also significantly changed under the influence of heat stress. This review aims to describe the effect of heat stress on systemic glucose metabolism, facilitative glucose transporters, and its consequences on health and milk production.

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The effect of sodium fertilisation of pasture on herbage production and the performance of lactating dairy cows

Proceedings of the British Society of Animal Production (1972) ◽

10.1017/s0308229600023709 ◽

1993 ◽

Vol 1993 ◽

pp. 41-41

Author(s):

A. Cushnahan ◽

F.J. Gordon

Keyword(s):

Dairy Cattle ◽

Dairy Cows ◽

Recent Work ◽

Milk Production ◽

Climatic Conditions ◽

Present Series ◽

Optimum Level ◽

Pasture Production ◽

Lactating Dairy Cows ◽

Production Response

Recent work by Chiy and Phillips (1991, 1992) has shown that the application of sodium (Na) fertiliser can produce improvements in pasture growth, pasture composition and the performance of grazing dairy cattle. However other studies have shown much smaller or zero effects in terms of pasture production following Na application (Smithet al., 1983; O'Connoret al., 1989). The objective of the present series of studies was to examine the milk production response to Na fertilisation of pasture under a differing set of soil and climatic conditions and to establish if there was an optimum level of Na input. In addition it was important to pursue the mechanisms of any animal production responses recorded. A series of studies were therefore undertaken to examine: (a) the influence of Na fertilisation of pasture on dairy cattle performance in comparison with any effects obtained through dietary Na supplementation, and (b) the effects of Na on herbage production, composition and digestibility.

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Instant Insights: Heat stress in dairy cattle

10.19103/9781786769343 ◽

2020 ◽

Keyword(s):

Heat Stress ◽

Dairy Cattle ◽

Animal Health ◽

Climatic Conditions ◽

Sub Saharan Africa ◽

Production Traits ◽

Smallholder Dairy ◽

Sub Saharan ◽

Economic Constraints ◽

The Impact

This specially curated collection features four reviews of current and key research on heat stress in dairy cattle. The first chapter outlines technologies to breed for more heat tolerant dairy cattle, exploiting either between or within breed genetic variation in the trait. It discusses future perspectives on the use of different tools to achieve accelerated improvements of this important trait. The second chapter discusses breeding goals and multi-trait selection to balance production and non-production traits. It considers newer breeding objectives such as ensuring that cattle can adapt to a changing climate, including breeding for heat tolerance. The third chapter reviews challenges facing smallholder dairy farmers in Asia. These include the impact of high temperatures and humidity on milk yield, reproductive efficiency and animal health. The chapter places these challenges in the context of the broader economic constraints faced by smallholders and how they can be overcome. The final chapter highlights constraints in improving smallholder dairy production in Sub-Saharan Africa. Issues include developing breeds balancing yield with resilience to local climatic conditions. The chapter reviews ways of Improving breeding and productivity, as well as broader organisational support.

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