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چکیده
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This experiment was conducted to compare conventional (CON; 21 d) and shortened (SH; 10 d) close-up period, and evaluate the effect of shortened close-up period combined with feeding different metabolizable protein (MP) levels on dry matter (DM) intake, metabolic status, and performance of dairy cows. Forty-eight multiparous Holstein cows with similar parity, body weight (BW), and previous lactation milk yield were divided into 2 groups. The first group (n = 24) received the far-off diet from −60 to −21 d (CON), and the second group (n = 24) received same far-off diet from −60 to −10 d (SH) relative to expected parturition. Cows were then moved to individual stalls and randomly allocated to 1 of 3 close-up diets: low MP diet (LMP; MP = 79 g/kg of DM), medium MP diet (MMP; MP = 101 g/kg of DM), or high MP diet (HMP; MP = 118 g/ kg of DM). Treatments were used in a 2 × 3 factorial arrangement with 2 lengths of close-up period (CON and SH) and 3 levels of MP (LMP, MMP, and HMP). All diets were fed for ad libitum intake during the closeup period. After calving, all cows received the same fresh cow diet. We found no interaction between closeup period length and MP levels for traits, except for postpartum serum fatty acids and β-hydroxybutyrate (BHB). The concentrations of postpartum serum fatty acids and BHB were higher on LMP than MMP and HMP diets in SH group. The cows of the SH group tended to produce less colostrum in the first milking than cows in CON group. The length of close-up period did not affect pre- and postpartum DM intake or energy balance of cows during the last week of prepartum, but cows of the CON group had greater BW changes during the last 3 wk before parturition than cows in SH group. Cows fed MMP and HMP diets consumed 1.2 and 1 kg more DM than for those fed LMP prepartum, respectively. The concentrations of prepartum BHB and Ca were higher for SH cows than CON group cows. Except for blood urea N concentration, no other blood metabolite in prepartu
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