Relationship between milk production and metabolic adaptation in dairy cows during heat stress

Abstract

Abstract:The aim of this study is to determine correlation between change in milk production and metabolic adaptation of cows during heat-stress. Experiment included 30 Holstein-Frisian cows. Cows exposed to heat-stress, which is expressed in high THI index, have lower milk production, higher concentration of insulin and lover concentrations of glucose and NEFA. Indexes of insulin resistance-RQUICKI, insulin: glucose and insulin: NEFA relations are higher in cows under heat stress. Grouping cows in accordance to reduced milk yield have showed that trend of reduction of glucose and NEFA levels, followed by increased insulin level, higher RQUICKI, greater insulin: glucose and insulin: NEFA ratios, started and increased during the reduction in milk production. Among this, significant correlation was founded between these parameters and milk yield. Significant correlation was also noted between those parameters. Change in metabolic value is of great importance for prediction of cows that would have decreased milk yield (above 18%). With almost 90% certainty cows with great reduction in milk yield can be detected. These cows have had following relative changes in values of metabolic parameters during heat-stress compared to thermo-neutral period: insulin increased for ≥12.5%, reduction in NEFA values for ≤14.1%, reduction in glucose for 21.5%, RQUICKI index increased for ≥9.6%, insulin: NEFA ratio increased for ≥20.1% and insulin: glucose for ≥20.3%. Dynamical changes in metabolites and insulin resistance Received 12 October 2017 Accepted 19 October 2017Acta Agriculturae Serbica, Vol. XXII, 44(2017); 123-131 124 values have great influence on milk yield in cows under heat stress. Decreasing in glucoses followed by increased insulin level and increased insulin sensitivity indicate that glucose is transferred from udder to other tissues which can cause decreased milk production.

Effects of increasing air temperature on physiological and productive responses of dairy cows at different relative humidity and air velocity levels

“…With regard to the response of increasing RR, Kadzere et al (2002) reported that about 15% of accumulated metabolic heat is dissipated by the respiratory tract for evaporative heat loss under hot conditions. Heat stress occurs when a cow is exposed to T that exceed her biological thermal comfort zone and has to make a lot of effort (and may even fail to) dissipate enough heat to maintain her body thermal balance (Majkić et al, 2017). Li et al (2020) reported that the rectal temperature (RT) of a high-producing cow started to increase when the ambient T was above 20.4°C.…”

Insulin resistance in cows during the periparturient period (review)

“…Heat stress is an important factor affecting insulin sensitivity in dairy cows. Results (Majkić et al, 2017) showed that: a) Cows exposed to heat-stress (high THI index) have lower milk production, higher concentrations of insulin and lower concentrations of glucose and NEFA; b) indices of insulin resistance-RQUICKI, insulin:glucose and insulin:NEFA are higher in cows under heat stress. The decrease in glucoses followed by an increased insulin level and increased insulin sensitivity indicate that glucose is transferred from the udder to other tissues, which can cause decreased milk production.…”

Occurrence of oxidative stress in sheep during different pregnancy periods

“…Lohi sheep account for 40% of national sheep production. Oxidative stress determination is the best tool for improved reproductive performance in sheep (El-Ratel et al, 2020) and cows (Majkić et al, 2017). As no significant information is available in the literature on Lohi sheep [48] on the physiological biomarkers concerning pregnancy and production at different stages, it is being hypothesized that these biomarkers during different stages of pregnancy and production will behave quite differently.…”