The effects of dietary L-carnitine and rumen-protected choline on growth performance, carcass characteristics and blood and rumen metabolites of Holstein Young bulls
2014
Hajilou, M. | Dehghan-Banadaky, M. | Zali, A. | Rezayazdi, K.
An experiment was conducted to determine the effects of L-carnitine (LC) and rumen-protected choline (RPC) on growth performance, carcass characteristics and blood and rumen metabolites of finishing bulls. Twenty-eight Holstein young bulls (average initial weigh 310±24 kg) were used in a completely randomized design with four treatments and seven replicates with 2×2 factorial arrangement for 90 days. Basal diets were formulated for 14% crude protein and 1.14 Mcal/kg of net energy for growth and contained 24% of dietary dry matter (DM) as corn silage, 6.8% alfalfa hay, 46.50% barley grain and 9.5% canola meal. Treatments included: (1) without LC and RPC or control; (2) 4g/d LC head ⁻¹; (3) 5 g/d RPC head ⁻¹; (4) 4 g/d LC head ⁻¹ and 5 g/d RPC head ⁻¹. Calves were fed ad libitum and had free access to fresh water. There were no differences between diets for DM intake, average daily gain and gain:feed. Plasma concentrations of glucose, insulin, nonesterified fatty acid, β-hydroxybutyrate, cholestrol and aspartate aminotransferase were not affected by treatments, but plasma triglyceride concentration decreased in calves fed RPC (P < 0.05). Longissimus muscle area, pelvic, kidney, heart and rumen and intestine fats were not affected by treatments. Subcutaneous fat and backfat thickness decreased in calves fed RPC (P < 0.05). LC and RPC had no significant effects on chemical composition of meat and liver (protein, fat, ash and dry mater). There was no significant difference between diets for rumen liquor volatile fatty acid and pH. This study showed that LC and RPC supplements cannot affect growth performance in Holstein young bulls, but lipid metabolism may be affected by LC and RPC.
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