The effect of rumen protected L-carnitine on feedlot performance, carcass characteristics and blood metabolites in Iranian fat-tailed Ghezel lambs

摘要

The effect of dietary protected L-carnitine on feedlot performance, carcass characteristics and blood metabolites of fat-tailed Ghezel lambs were studied. Twenty four ram lambs (180±30 d) were randomly allotted to four groups. The lambs were housed in individual cages and had free access to feed and water. The animals were fed diets containing 0.0 (control), 0.5, 1.0 or 1.5 g/d rumen protected L-carnitine. Dry mater intake (DMI), average daily gain (ADG), feed conversion ratio (FCR), and blood cholesterol, glucose and urea were measured. After 80 d fattening period, the lambs were slaughtered and weight of hot and cold carcasses, tail fat, visceral fat, pelvic fat, back fat thickness, kidney, kidney fat, heart, heart fat, and lungs was determined for each group. Back fat thickness and the cross sectional area of the Longissimus dorsi muscle were measured at 12 th /13 th rib. Meat samples were taken between rib 9 to 13 for determination of meat colour and contents of protein, fat, moisture and malondialdehyde. The highest level of L-carnitine increased visceral fat percentage in carcass (P<0.05). Meat colour was improved (P<0.05) by L-carnitine feeding. Plasma cholesterol concentration on d 40 of the fattening period decreased (P<0.05) in animals receiving 1.5 g/d L-carnitine; however, on d 80, it increased to level recorded on d 0. Other characteristics were not significantly affected by L-carnitine feeding. We concluded that L-carnitine at the current levels had no significant effect on growth; however, meat texture was improved at the rate of 1.0 g/d L-carnitine.