title: Feeding micronized and extruded flaxseed to dairy cows: effects on blood parameters and milk fatty acid composition.
abstract: Four lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design to determine the effects of feeding micronized and extruded flaxseed on milk composition and blood profile in late lactation. Four diets were formulated: a control (C) diet with no flaxseed, a raw flaxseed (RF) diet, a micronized flaxseed (MF) diet, and an extruded flaxseed (EF) diet. Flaxseed diets contained 12.6% flax-seed (dry matter basis). Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection. Feeding flaxseed reduced milk yield and energy-corrected milk by 1.8 and 1.4 kg/d, respectively. Yields of milk protein and casein were also lower for cows fed flaxseed diets than for those fed the C diet. Milk yield (1.6 kg/d) and milk fat percentage (0.4 percentage unit) were lower for cows fed EF than those fed MF. Plasma cholesterol and nonesterified fatty acid concentrations were higher for cows fed flaxseed diets relative to those fed the C diet. Flaxseed supplementation decreased plasma concentrations of medium-chain (MCFA) and saturated (SFA) fatty acids and increased concentrations of long-chain (LCFA) and monounsaturated fatty acids. Feeding flaxseed reduced the concentrations of short-chain fatty acids (SCFA), MCFA, and SFA in milk fat. Consequently, concentrations of LCFA and unsaturated fatty acids were higher for cows fed flaxseed diets than for those fed the C diet. Flaxseed supplementation increased average concentrations of C(18:3) and conjugated linoleic acid by 152 and 68%, respectively. Micronization increased C(18:3) level, and extrusion reduced concentrations of SCFA and SFA in milk. It was concluded that feeding raw or heated flaxseed to dairy cows alters blood and milk fatty acid composition. Feeding extruded flaxseed relative to raw or micronized flaxseed had negative effects on milk yield and milk composition.
authors.affiliation: Department of Animal Science, McGill University-Macdonald Campus, Ste-Anne-de-Bellevue, QC, Canada H9X 3V9.
authors.forename: C
authors.initials: C
authors.lastname: Gonthier
authors.forename: A F
authors.initials: AF
authors.lastname: Mustafa
authors.forename: D R
authors.initials: DR
authors.lastname: Ouellet
authors.forename: P Y
authors.initials: PY
authors.lastname: Chouinard
authors.forename: R
authors.initials: R
authors.lastname: Berthiaume
authors.forename: H V
authors.initials: HV
authors.lastname: Petit
mesh_terms: D000818:Animals; D002364:Caseins / Q000032:analysis; D002417:Cattle / Q000097:blood / Q000378:metabolism*; D002784:Cholesterol / Q000097:blood; D004032:Diet; D004435:Eating; D005227:Fatty Acids / Q000032:analysis* / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D019597:Flax; D005511:Food Handling / Q000379:methods*; D006358:Hot Temperature; D007774:Lactation; D044243:Linoleic Acids, Conjugated / Q000032:analysis; D008055:Lipids / Q000032:analysis / Q000097:blood*; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis
chemical_list: D002364:Caseins; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D044243:Linoleic Acids, Conjugated; D008055:Lipids; D008894:Milk Proteins; D002784:Cholesterol