Nutrient digestion, biohydrogenation, and fatty acid profiles in blood plasma and milk fat from lactating Holstein cows fed canola oil or canolamide

The effects of feeding protected or unprotected canola oil on intake, nutrient digestibility, duodenal fatty acid flows, milk yield, and milk composition were evaluated using four Holstein cows cannulated in the rumen and proximal duodenum. Cows were fed a control diet (CON) or the control diet supplemented at 3.3% of dry matter with canola oil (OIL), canolamide (AMD) (made by reacting canola oil with ethanolamine), or a mixture of equal amounts of canola oil and canolamide (MIX) in a 4 × 4 Latin square with four 21-day periods. Milk yield and dry matter intake averaged 38 and 24 kg per day, when OIL or MIX were fed, but decreased to 33 and 19 kg per day when cows were fed AMD as the only supplemental source of cis9-18:1. Total tract digestibility of dry matter (70%), crude protein (71%), and fiber (49%) was not affected by treatments. Oleic acid intake was higher due to feeding AMD (438 g per day), OIL (530 g per day), or MIX (531 g per day) compared with CON (120 g per day). Biohydrogenation of cis9-18:1 (40 versus 77%) increased when all forms of supplemental oleic acid were fed. Cis9, trans 11-8:2, trans 11-18:1, and 18:0 flows to the duodenum were greater when OIL (3, 104, and 647 g per day) was fed compared with AMD (0, 29, and 372 g per day). Flow of cis9-18:1 to the duodenum was greater (103 g per day) in response to supplemental fat compared with CON (65 g per day). Plasma total fatty acids and cis9-18:1 increased 15 and 61% in response to supplemental oleic acid. Milk fat percentage was not affected by treatments, but concentrations of saturated 8:0 to 16:0 in milk fat were lower when cows were fed supplemental cis9-18:1 (41%) compared with CON (58%). Cis9, trans 11-18:2 and trans 11-18:1 concentrations in milk fat were greater when OIL (1.1 and 4.5%) was fed compared with AMD (0.7 and 2.9%). Concentrations of cis9-18:1 in milk fat ranked by treatment were AMD (28%)=OIL (26%) > MIX (24%) > CON (16%). Converting canola oil to an amide provided partial protection against biohydrogenation of cis9-18:1. Whether fed as an oil or amide, however, supplemental cis9-18:1 elevated concentrations of oleic acid in plasma and milk fat.