The effects of chemical treatment of whole canola seed on intake, nutrient digestibilities, milk production, and milk fatty acids of Holstein cows.

To determine the effect of alkaline hydrogen peroxide treatment of whole canola seed on milk fatty acid composition, 12 multiparous lactating Holstein cows (618 kg, 47 d in milk) were fed total mixed rations in a replicated (3) 4 x 4 Latin square designed experiment. The control diet contained no supplemental fat source. Canola seed (11.2%), either crushed or treated with alkaline hydrogen peroxide or Megalac (5.6%) were supplemental fat sources in the crushed, treated, and calcium salts of long-chain fatty acids (Ca-LCFA) dietary treatments. Experimental periods consisted of 28 d, with 21 d of adaptation to diets and 7 d for data collection. Cows were offered ad libitum access to feed. Intakes, ruminal characteristics, and total tract apparent digestibilities were measured and are discussed. Production of milk and 4% fat-corrected milk were not different among treatment groups (average 35.0 and 32.8 kg/d, respectively). Milk fat percentages were greater (P = .02) for cows fed treated canola seed or Ca-LCFA than for cows fed crushed canola seed (average 3.71 vs 3.43%, respectively), but milk fat yield (kg/d) was unaffected. Cows fed fat-supplemented diets had lower milk protein percentages than cows fed the control diet. Within the fat-supplemented diet groups, cows fed crushed canola seed had greater milk protein percentages (P = .01) and yields (P < .01) than cows fed treated canola or Ca-LCFA. Milk fat from cows fed diets supplemented with canola seed (treated or crushed) had lower proportions of 14:0 and 16:0 and greater proportions of 18:0 and 18:1 than milk fat from cows fed the control or Ca-LCFA diets. Intakes, milk production, milk composition, and milk fatty acid profiles substantiate that treated canola seed was utilized by cows to an extent similar to that of crushed canola seed. Further definition of the method for treatment of canola seed may provide a strategy for adding higher levels of monounsaturated fatty acids to lactation diets to produce favorable alterations in milk fat composition.