title: Effect of combinations of fish meal and feather meal on milk fatty acid content and nitrogen utilization in dairy cows.
abstract: The effect of supplemental fishmeal in combination with feathermeal at two different proportions in the diet on milk docosahexaenoic acid (DHA) content was investigated. Recently, benefits to human health have been attributed to the consumption of this fatty acid, which is normally present in marine lipids. Six Holstein cows past peak lactation were used in a Latin square design with a 2 x 3 factorial arrangement of treatments. Fish- and feathermeals were prepared as pellets at 4:1 and 1:4 combinations and offered at 3.75, 11.75, and 27% of the diet. The supplements were top-dressed onto a basal diet based on corn silage that was progressively replaced by supplement. Nitrogen balance measures were made during the experiment because of the wide range in crude protein content of experimental diets. Milk protein content increased with level of supplementation in the diet reflecting the protein quality of the supplements used. There was overall higher milk DHA content when cows consumed the supplement containing more fishmeal than feather meal. Milk DHA content increased in a quadratic fashion, as more of either supplement was included in the diet. Apparent transfer efficiency of DHA from diet to milk declined with increasing amount of DHA in the diet. Results from this experiment suggest that transfer of docosahexaenoic acid from diet to milk may depend on diet composition and quantity present in the diet.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: T C
authors.initials: TC
authors.lastname: Wright
authors.forename: B J
authors.initials: BJ
authors.lastname: Holub
authors.forename: A R
authors.initials: AR
authors.lastname: Hill
authors.forename: B W
authors.initials: BW
authors.lastname: McBride
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet; D004063:Digestion; D004281:Docosahexaenoic Acids / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism; D005227:Fatty Acids / Q000008:administration & dosage / Q000032:analysis* / Q000378:metabolism; D005241:Feathers; D005260:Female; D005396:Fish Products; D007774:Lactation; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism; D012820:Silage; D003313:Zea mays
chemical_list: D005227:Fatty Acids; D008894:Milk Proteins; D004281:Docosahexaenoic Acids; D009584:Nitrogen