Relief of The Impact of Heat Stress on Friesian and Cross-Bred Friesian Dairy Cows by Water Showering under Egyptian Hot Humid Summer Conditions in Nile Delta

The present study aimed to evaluate the response of lactating purebred Friesian cows and crossbred Friesian with Baladi cows during hot-humid Egyptian summer conditions to showering. The experimental work was carried out during June – August. Ten Friesian and ten crossbred Friesian × Baladi dairy cows were used and assigned randomly into four treatment groups: two control groups of cows had access only to shade (Friesian cows and crossbred Friesian cows; S), and two groups were provided showers (Friesian cows and crossbred Friesian cows; S + S). The maximum THI throughout the experimental work was 80.43 to 85.22. Showered cows were taken to a holding pen daily to be cooled. Concentrations of TSH, T 3 , T 4 , IGF-1, glucose, cholesterol, triglyceride, total protein, albumin, ALP, Na, K, and milk production were significantly (P<0.01) increased, while, serum cortisol, prolactin, creatinine, AST, ALT and thermoregulatory traits (rectal temperature; RT, respiration and pulse rate (RR; PR), and skin temperature; ST were significantly decreased (P<0.01) in showering than shaded only Friesian and crossbred Friesian cows. Despite crossbred Friesian-Baladi dairy cows displaying more tolerance for heat through attained better parameters for thermoregulatory, endocrinal, and biochemistry and milk production, the amount of improvement of purebred Friesian dairy cows by showering enables cows to express some of their genetic potentials which impeded by the heat stress. Thus, showering can be used to lessen the impact of hot-humid Egyptian summer conditions in the Nile Delta on heat-sensitive exotic purebred dairy cows.