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Abstract

Records obtained from a commercial dairy farm, covering a period of 26 years, were analyzed to evaluate the effect of coat color on milk production and reproduction in Holstein cows. There was no difference (P >. 10) in the amount of milk produced during the first lactation or length of the first lactation among cows with 25, 26-50, 51-75 or >75% black hair coat (BHC). Cows with > 75% BHC had more conceptions (P < .009) in January and February and fewer in March, April and June than cows with < 75% BHC (-2 = 25.16). Light colored cows ( 25% BHC) had shorter (P < .03) calving intervals than darker cows (> 25% BHC; 464 ± 14 vs 495 ± 5 d, respectively) independent of month of calving. These results indicate that milk production of Holstein cows in the tropics is not influenced by coat color but reproduction may be. Cows with more black surface area may be more susceptible to detrimental effects of heat stress because more solar radiation is absorbed as heat.

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