Amelioration of thermal stress impacts in dairy cows

Abstract

Heat stress negatively impacts on a variety of animal production parameters. Advances in management strategies have alleviated some of the negative impacts of thermal stress on farm animals, but production continues to markedly decrease during heat events in summer, particularly in dairy cattle. In this paper we introduce a Dairy Risk Assessment Program (DRAP). The DRAP is a user-friendly software package designed to assist users in predicting heat loads in dairy cow herds. DRAP was developed over three Australian summers using climatic data (temperature, humidity, solar radiation and wind speed), cow production data (milk yield and milk quality), and physiological data (respiration rate and body temperature). The data were used to develop mathematical algorithms which can predict animal response to climatic variables. This software package is designed to be used by the dairy industry to better manage cows during times of elevated environmental temperatures by equipping producers, managers, and dairy industry personnel with Dairy Heat Load Index (DHLI) values which were calculated based upon site information, stock characteristics, management practices, and mitigation variables specific to their dairy production unit. When a heat event is imminent producers can then introduce management strategies such as providing shade or additional water troughs or implementation of nutritional strategies. Some of these nutritional strategies include dietary chromium picolinate, betaine and antioxidant supplementation or altering the rate of starch fermentation. These nutritional strategies are discussed at some length in this paper.

Factors influencing the incidence of high rigor temperature in beef carcasses in Australia

“…First, grainfed cattle have recently been reported to have a higher core body temperature by 0.3-0.4 C than grass-fed cattle (Jacob et al 2014b). In this context, dairy cattle fed concentrate rations containing rapidly fermentable wheat had a higher flank temperatures as well as greater differences between left and right flank temperatures than dairy cows fed maize-based diets (see Dunshea et al 2013) indicating that the type of grain can also impact on body temperature. Second, as discussed above, the rate of temperature decline post mortem would be slower for the fatter, heavier carcasses resulting from grain feeding.…”

Dietary nano-chromium tripicolinate increases feed intake and decreases plasma cortisol in finisher gilts during summer

“…In a rodent model, dietary nCr improved growth rate and feed efficiency in heat-stressed rats (Zha et al 2009). The risk of high rigour temperature of beef carcasses increases with increasing insulin resistance (Warner et al 2014), and it has been proposed that the ability of dietary Cr to improve insulin sensitivity may provide a means of ameliorating heat shortening in beef cattle (DiGiacomo et al 2014) and heat stress in dairy cattle (Dunshea et al 2013). However, there are no studies investigating the effect of Cr on heat stress or during hot condition in finishing pigs.…”

Potential nutritional strategies for the amelioration or prevention of high rigor temperature in cattle – a review

“…We recently reviewed these responses in lactating dairy cattle in depth (Dunshea et al 2013), and thus the responses in lactating cattle will not be covered here. Prolactin modulates sweat gland function (Alamer 2011) and is involved in maintaining electrolyte and water balance in the heat-stressed mammalian gut, kidney and mammary gland (Collier et al 1982;Faichney and Barry 1986).…”