Effect of feeding formaldehyde- and heat-treated oil seed on milk yield and milk composition

The primary objective of this study was to determine the effect of formaldehyde-treated oil seed on milk composition, with particular emphasis on the fatty acid and protein composition of milk. Ground and heat-treated canola seed treatments were included for comparison purposes. Four early-lactation Holstein cows were assigned to four treatments in a 4 x 4 Latin square design. Cows were fed a control diet containing 60% concentrate, 20% alfalfa silage and 20% barley silage (DM basis). The concentrate portion was based on rolled barley, canola meal, and ground corn. Canola seed replaced barley and canola meal in the control diet at 5% on a DM basis. Dry matter intake (21.0 +/- 0.1 kg d(-1)), milk yield (33.3 +/- 1.57 kg d(-1)), milk component yield and milk protein and lactose percentages were not affected (P> 0.05) by dietary treatment. Cows fed untreated ground canola seed had lower (P < 0.05) milk fat percentage than cows fed the other treatments. The addition of untreated and heat-treated canola seed reduced palmitic acid (15%) and increased oleic acid (14%), but had no effect on linoleic and linolenic acid concentrations. Formaldehyde treatment resulted in a 76 and 123% increase in C-18:2 and C-18:3, respectively over the control diet, whereas untreated and heat-treated canola seed did not influence the concentration of these fatty acids. Effects of treatments on milk protein and non-protein nitrogen components were minor or nonexistent. Transfer efficiencies calculated for linoleic and linolenic acid indicated that formaldehyde treatment was efficacious in significantly reducing the extent of biohydrogenation of fatty acids in the rumen.