Heat stress alleviating measures for crossbred cows

Abstract

An experiment was conducted to find the effect of sprinkling water on crossbred cows during summer season of Kerala.Twelve early lactating crossbred cows were selected and put into four groups of three each and were randomly allotted to four treatments as open house with sprinkler (T1), open house without sprinkler (T2), tie-barn with sprinkler (T3) and tie-barn without sprinkler (T4). The mean maximum temperature recorded in the T1, T2, T3 and T4 locations were 32.03, 32.17, 33.27 and 33.40oC respectively and these were lower than the maximum temperature recorded outside the animal houses (35.45oC). Both within the tie-barn and within the open house, the mean maximum and minimum temperatures and mean relative humidity morning and afternoon did not differ significantly due to sprinkling of water.But the differences between the tie-barn and open house were highly significant (P<0.01) and higher in the tie-barn for all these variables. Physiological reaction such as rectal temperature, respiratory rate and cardiac rate did not vary significantly between treatments for morning recording. For afternoon recording the differences were highly significant. Sprinkling of water in T1 and T3 markedly reduced the diurnal rise in physiological norms compared to T4. The difference between T2 and T3 was comparable. Mean weekly milk yield of cows in T1, T2 and T3 increased by 4.70, 1.22 and 1.71 kg per head respectively compared with T4. Milk composition such as total solids, solids not fat, protein and fat percentages did not vary significantly between treatments. Green grass consumption differed significantly between treatments and highest in the T1 (26.16 kg per cow). Daily water consumption differed significantly between treatments and highest in the T4 (31.72 kg). Haemoglobin, packed cell volume and erythrocyte sedimentation rate differed significantly (P<0. 01) between treatments. There was a uniform loss in body weights of all the experimental cows as lactation progressed upto the peak yield stage, thereafter the cows had shown tendency to regain body weights irrespective of the type of treatment given. Sprinkling water in T1 and T3 encouraged the feeding and rumination of cows during hot hours of the day and consumed significantly more feed. Sprinkling of water in T1 and T3 increased the intensity and duration of oestrus 'and successful insemination rate. The results suggest that during the summer season of Kerala tree shade or simple shade areas with roof supported on pillors affording maximum ventilation and sprinkling or splashing of water during hot hours of the day may be practiced to alleviate heat stress and reduce drop in milk production and fertility rate during summer.