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 formalde hyde-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 des ign. Cows were fed a control diet containing 60% concentrate, 20% alfalfa s ilage and 20% barley silage (DM basis). The concentrate portion was based o n 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 componen t 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 additio n of untreated and heat-treated canola seed reduced palmitic acid (15%) and increased oleic acid (14%), but had no effect on linoleic and linolenic ac id concentrations. Formaldehyde treatment resulted in a 76 and 123% increas e in C-18:2 and C-18:3, respectively over the control diet, whereas untreat ed and heat-treated canola seed did not influence the concentration of thes e fatty acids. Effects of treatments on milk protein and non-protein nitrog en components were minor or nonexistent. Transfer efficiencies calculated f or linoleic and linolenic acid indicated that formaldehyde treatment was ef ficacious in significantly reducing the extent of biohydrogenation of fatty acids in the rumen.