Nutritive Value of Formaldehyde-Treated Rapeseed Meal for Dairy Calves

Treatment of oilseed meals with formaldehyde (FA) and glutaraldehyde (GA) significantly (P < 0.01) reduced the solubility of protein in 0.02 N NaOH and the production of NH 3 in the artificial rumen. Ten Holstein and Holstein × Brown Swiss calves of both sexes were fed two test rations containing either 26% untreated or formaldehyde-treated (5.6 g FA per 100 g protein) rapeseed meal (FA-treated RSM) for 14 weeks. Plasma urea nitrogen (N) and rumen NH 3 levels were significantly (P < 0.01) lower in the FA-treated RSM calves compared with the control calves during the first 8 weeks of the growth trial. No significant difference (P > 0.05) in dry matter consumption, daily gain, or feed efficiency was observed. Total volatile fatty acids (VFA) (mmoles/100 ml) concentration was significantly higher (P < 0.05) in rumen fluid from the control calves compared with those receiving treated RSM. Molar percentages of the VFA’s were not significantly different (P > 0.05) between the two groups. In the N balance and digestibility trial, dry matter consumption did not differ significantly (P > 0.05); however, the FA-treated RSM resulted in decreased (P < 0.05) dry matter and crude protein digestibility. Calves receiving the treated RSM had reduced (P < 0.01) urinary N excretion; however, there was no significant effect (P > 0.05) on N consumption and retention.