Effects of supplemental carnitine on nitrogen balance and blood metabolites of growing beef steers fed a high-protein, corn-based diet

摘要

Seven Angus-cross steers (475 lbs initialbody weight) were used in a 7 × 4 incompleteLatin square experiment to evaluate the effectsof supplemental L-carnitine on nitrogen balanceand blood metabolites. Steers were fed thesame high-protein, corn-based diet near adlibitum intake. Treatments were control and.25, .5, 1.0, 1.5, 2.0, and 3.0 grams/day ofsupplemental carnitine. Experimental periodswere 18 days with 13 days for adaptation and5 days for collection of feces and urine. Bloodwas collected at feeding and 3 and 6 hours afterfeeding on day 18 of each period. Supplementingsteers with carnitine increased urinary carnitineexcretion and plasma carnitine concentration.Nitrogen retention (a measure of proteindeposition) was not affected by carnitinesupplementation and averaged 29.3 g/d.Plasma insulin and glucagon, indicative of energystatus, and cholesterol and triglyceride, representativeof energy storage metabolites, werenot affected by carnitine supplementation.Plasma glycerol and beta-hydroxybutyrate,reflective of fat catabolism, increased withintermediate levels of supplemental carnitine. Inconclusion, carnitine supplementation did notalter N balance in our experiment, but it did altersome of the plasma metabolites of steers fedhigh-protein, corn-based diets.