Effects of dry period length on milk yield and composition, blood metabolites, follicular dynamics and complete blood count in Holstein dairy cows

Twenty-nine Holstein dairy cows were used to evaluate the effect of dry period (DP) length on milk yield and composition, some blood metabolites, complete blood count (CBC) and follicular dynamics. Cows were assigned to either one of two treatments including: (1) 60-d dry period (n = 14) and (2) 35-d dry period (n = 15). Milk yield, from calving to 60 days postpartum was not different for cows in the two treatments (p = 0.130). Cows in the 35-d DP produced more milk protein, lactose and SNF compared with those of cows in treatment 1 (p< 0.05). Serum glucose, non-esterified fatty acids (NEFA), beta-hydroxybutyric acid (BHBA), blood urea nitrogen (BUN) and glutamic oxaloacetic transaminase (GOT) were all similar for both treatments. Body condition score (BCS), body weight (BW), complete blood count (CBC) and follicular dynamics were also similar between the cows allocated in the treatments. Results of present study provided useful information to apply in dairy cow management when dry period length has been considered.