Master of Science (MS)


Animal Science (Animal, Dairy, and Poultry Sciences)

Document Type



A study was conducted to determine effects of differing fat and protein levels in commercial milk replacers on the growth performance and rumen development of neonatal Holstein calves. Fifty-three calves (23 male; 30 female) were assigned to one of three dietary treatments which included 3 milk replacers (20/20; 25/15; 28/20) fed once per day at 10% of birth weight through weaning. Calves were offered a 20% CP calf starter and water free choice beginning on day 5. All calves were weaned on day 42. Body weights were measured at birth and weekly through weaning. Additionally, hip height, wither height, and body length were measured weekly. Feed intake and fecal scores were recorded twice daily. Beginning on day 7 and continuing weekly through weaning, blood samples were collected prior to morning feeding for analysis of IGF-I and on days 14, 28, 42, and 56 for PUN and â-hydroxybutyrate concentrations. On days 28 and 56 rumen fluid was collected for analysis of pH and VFA to evaluate possible differences in rumen development. Calves fed 28/20 milk replacer had greater (P < 0.05) daily starter intake, body weights, PUN, and â-hydroxybutyrate concentrations when compared to calves fed 20/20. There was also a treatment by week interaction (P < 0.05) for starter intake, with calves on 28/20 milk replacer consuming the greatest amounts after week 3 and maintaining the greater starter intake through week 8. A treatment over time effect was observed for fecal scores (P < 0.05). No other differences were observed (P > 0.05) in fecal scores among any treatments. Average wither heights were greater (P < 0.05) in calves fed 28/20 milk replacer. There were no effects (P > 0.05) of treatment on IGF-I concentrations, rumen pH, or concentrations of VFA. Acetate, as a percent of total VFA, tended (P < 0.10) to be greater in calves fed 28/20 milk replacer. These data indicate that increasing the dietary protein content of milk replacer without reducing fat content improved growth in young dairy calves without compromising health or rumen development.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cathleen C. Williams