Eefect Of Heat Stress On Perfprmance Of Dairy Friesian Cows 1-Milk Production And Composition Researcher

Abstract: A total of 1243 available records were collected for 581 Friesian cows during 8 year period from 1997 to 2004 were used to study heat stress on milk production and composition. Average temperature humidity index (THI) values confirm the presence of heat stress during the period from June to September (summer season). Heat stress during summer season led to significant decrease (P<0.05) in lactation period by 35 day and reduced total, 305 and daily milk yield by 39.00, 31.40 and 29.84% and the percentages of fat, protein, lactose, solids not fat, total solids and ash by 7.92, 4.06, 3.97, 4.03, 5.21 and 5.63% compared with winter season, respectively