Lactational, In Vitro, and Chemical Evaluation of Untreated and Formaldehyde-Treated Casein Supplements

Supplemental feeding of casein treated with .8% wt/wt formaldehyde was compared with untreated casein or no supplement for eight Holsteins averaging 29 kg milk/day. Compared to untreated casein, formaldehyde-treated casein supplementation had no significant effect on yield of milk or milk components except for a small increase in secretion of milk urea. When supplemental treated casein was compared with no supplement, yields of milk, total protein, "true" protein, and urea in milk increased. Urea and albumin concentrations in plasma were not affected by dietary treatments, and there was a small correlation between urea in plasma and milk.