Abstract
The high energy, protein, and fiber contents of whole cottonseed make it a potential candidate for the inclusion in calf starters to promote the rumen development. This study aimed at assessing whether the inclusion of whole cottonseed in the starter would affect performance, metabolic profile, and rumination time in Holstein dairy calves. From 2 to 55 d of age, 12 heifer calves were fed a constant amount of milk replacer twice daily (8 L/d), whereas from 56 to 65 d (weaning) milk replacer was gradually reduced (from 4 to 1 L/d) and fed in a single meal. Calves were blocked by birth body weight and % Brix of colostrum received and randomly assigned to 1 out of 2 dietary treatments: (1) control starter (CTR); (2) starter with 8% inclusion of whole cottonseed (WCS). Treatments were fed for ad libitum intake. From d 56, TMR and hay were offered ad libitum. At 0, 2, 7, 21, 65, and 80 d, BW was measured and blood samples were collected. Feed intake and rumination time were automatically recorded. Compared with CTR, WCS calves were heavier at weaning and after weaning, and consumed more starter from 59 to 72 d. In the immediate postweaning (from 66 to 72 d of age), rumination time increased more in WCS calves. Overall, WCS calves had greater plasma glucose, β-carotene, and retinol concentrations, whereas ceruloplasmin and myeloperoxidase were lower. Calves in the WCS group had greater glucose concentration at 21 and 65 d and lower urea at 65 d (weaning). Plasma β-carotene concentration was greater at 65 and 80 d in calves of the WCS group compared with CTR calves. At 80 d, WCS calves had lower plasma alkaline phosphatase and greater β-hydroxybutyrate, paraoxonase, and tocopherol. These results suggest that inclusion of WCS in the calf starter might be beneficial for rumen development, leading to greater feed intake and BW. Moreover, WCS inclusion was associated with lower oxidative stress and inflammation, improved energy metabolism and liver functionality, and likely quicker rumen development, as might be indicated by the higher plasma β-hydroxybutyrate and rumination time. These changes occurred mainly after weaning, when no differences in starter intake and average daily gain were detected, suggesting a better efficiency of nutrient utilization at this age.