Effect of added dietary fat on performance, rumen characteristics, and plasma metabolites of midlactation dairy cows.
Effects of supplemental Jet-Sploded canola seed in the diets of dairy cows on milk yield and composition and blood metabolite concentrations were investigated. Twenty multiparous and 5 primiparous midlactation Holstein cows were assigned to treatments following a 3-wk covariate period; cows were then on the treatments for 70 d. Ten of the cows had previously been fitted with rumen cannulas. Five concentrate mixtures containing 0, 7.5, 15, 22, or 29% Jet-Sploded canola seed (Simons Feed Co., Quimby, IA) (equivalent to 0, 2.66, 5.33, 7.81, and 10.30% added fat, respectively) were formulated by substituting Jet-Sploded canola seed for barley and canola meal. Diets consisted of 25% alfalfa silage, 25% whole-crop oat silage, and 50% of one of the concentrate mixtures (dry matter basis). An increase in the amount of dietary fat from Jet-Sploded canola seed did not influence feed intake, milk yield or composition, or milk component yields. The inclusion of Jet-Sploded canola seed in the diet increased long-chain fatty acids and inhibited de novo synthesis of medium-chain fatty acids in milk. Mean total volatile fatty acids in the rumen and propionate concentration were reduced in a linear fashion by treatment. The inclusion of Jet-Sploded canola seed in the diets of mid-lactation cows altered rumen and blood metabolite concentrations; however, these changes had minimal effects on yield responses with the exception of milk fatty acid composition and milk protein content.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
G R
GR
Khorasani
J J
JJ
Kennelly
D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage*; D004435:Eating; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D005285:Fermentation; D007774:Lactation; D008892:Milk / Q000737:chemistry; D012417:Rumen / Q000378:metabolism*
D004041:Dietary Fats; D005232:Fatty Acids, Volatile