Effects of varying levels of cottonseed hulls on growth and metabolic indications of rumen development of dairy calves

Abstract

A study was conducted to determine the effects of varying levels of cottonseed hulls on growth and metabolic indications of rumen development of dairy calves. Sixty-four Holstein calves (Heifers, n=40; Bulls, n=24) were randomly assigned to one of four dietary treatments which included calf starters containing no cottonseed hulls (control; C), 10% cottonseed hulls (10% CSH), 15% cottonseed hulls (15% CSH), or 20% cottonseed hulls (20% CSH). Calves were fed their respective treatments beginning on day 6 until day 56 of age. Body weights were measured at birth and biweekly thereafter until day 56 of age. Wither and hip heights were measured beginning on day 14 and biweekly thereafter until day 56 of age. Feed intake and fecal scores were recorded twice daily through day 56. On days 14, 28, 42, and 56, rumen fluid was collected for analysis of pH, volatile fatty acids (VFA), and ammonia (NH3), and blood was collected for analysis of plasma urea nitrogen (PUN) and â-hydroxybutyrate (BHBA). There was no treatment effect on average daily starter intake, body weight, wither height, and hip height but a treatment effect on fecal scores. Calves consuming CSH had higher rumen pH than C. Rumen pH also decreased as calves aged. There was no treatment effect on rumen acetate, propionate, butyrate, and total VFA concentrations. A treatment effect on NH3 concentrations was observed, and NH3 concentrations decreased over time. There was no treatment effect on BHBA, but a main effect of sex was observed in which the males had greater BHBA levels. There was no treatment effect on PUN concentrations, but a main effect of sex was observed with females having greater PUN concentrations. Overall, incorporating cottonseed hulls into a calf starter showed no significant effect on growth and rumen development in Holstein dairy calves.