Fateme Ahmadi; hamid Amanlou; Tahere Amirabadi Farahani; Najme Eslamian Farsuni
Volume 24, Issue 4 , December 2022, , Pages 415-425
Abstract
The aim of the present study was to evaluate the effect of supplementing close-up diets of Holstein dairy cows with rumen undegradable protein (RUP) on milk yield, calf birth weight and colostrum composition during the hot season. Eighty-eight multiparous Holstein dairy cows were enrolled in the study ...
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The aim of the present study was to evaluate the effect of supplementing close-up diets of Holstein dairy cows with rumen undegradable protein (RUP) on milk yield, calf birth weight and colostrum composition during the hot season. Eighty-eight multiparous Holstein dairy cows were enrolled in the study 30 d before expected calving and assigned to 1 of 2 treatments groups: low crude protein (14.3% CP with 4.0% RUP based on DM) and high crude protein (17.1% CP with 6.0% RUP based on DM). Diets were fed for ad libitum intake during the close-up and fresh period. After calving, all cows received the same diet from calving to 21 days of milk. Milk production of all cows was recorded daily from the day of calving to 21 days after calving. The milk samples of each cow were collected twice a week to measure milk composition. The evaluation of body condition score (BCS) was performed at -30, -3, 0, and 21 d relative to calving. The production of milk and the amount of milk protein and lactose were greater and milk fat content was lower in cows fed high protein diet than cows fed low protein diet (P<0.05). The BCS changes were not different between cows of two treatments in pre- and post-partum periods. According to the results, feeding a diet containing high RUP content to close-up cows during the hot season increases milk yield and decreases milk fat percentage in fresh cows.