Quality of protein in milk replacers for young calves part 2 effects of heat treatment of skim milk powder and fat levels on calf growth feed intake and nitrogen balance
Lister, E.E.; Emmons, D.B.
Canadian Journal of Animal Science 56(2): 327-334
1976
ISSN/ISBN: 0008-3984 Accession: 006238232
Three spray-dried powders were prepared after heating skim milk for 30 min at 60.degree. C (LT), 73.9.degree. C (MT) or 85.degree. C (HT). Each was reconstituted to 2 concentrations of dietary fat and fed to 5 or 6 calves for 26 days after purchase at .apprx. 1 wk of age. Calves receiving the HT skim milk had significantly (P < 0.05) higher incidence of diarrhea and slower rate of gain over 19 days on test as compared with those fed the MT and LT skim milks. Subsequently growth rate was unaffected by the skim milk source and there were interactions of fat level with skim milk source. The high fat level (22.2% of dietary dry matter) resulted in a higher incidence of alopecia than in calves receiving the low fat level (16.2% of dietary dry matter). Nutrient digestibilities and N balance, measured from day 20-26, were unaffected by skim milk treatments or fat concentrations. Young calves, less than 3 wk of age, apparently require a diet based on skim milk that has not been severely heat-treated and the curd formation is a suitable index of quality for such milk replacer diets. Where control diets for milk-replacer studies are designated all milk protein, it is important for correct interpretation to define their curd-forming characteristics. For older calves, coagulation appears not to be a requirement.