Dietary L-carnitine improves nitrogen utilization in growing pigs fed low energy, fat-containing diets.
Growing pigs (n = 25; 17.8 +/- 0.1 kg) were used to study the effects of L-carnitine and protein intake on nitrogen (N) balance and body composition. Fat-supplemented (40 g soy oil/kg diet), corn-soybean meal basal diets containing low or high protein (136 or 180 g/diet) were formulated so that protein accretion would be limited by metabolizable energy (ME). Each basal diet was supplemented with 0 or 500 mg/kg L-carnitine and fed to pigs for 10 d in a nutrient balance trial. Final body composition was compared with weight and age-matched pigs measured on d 0 to calculate nutrient accretion rates. High protein feeding increased (P < 0.01) average daily gain (ADG) by 34%, as well as nitrogen digestibility (4.4%), retention (5.2%), urinary excretion (29%) and crude protein (CP) accretion (33%). Total-body carnitine accretion rate was 4.5 fold greater and total body carnitine concentration was almost 100% greater than in unsupplemented controls (P < 0.01). Irrespective of protein level, carnitine increased ADG (by 7.3%, P < 0.10) and CP accretion rate (9%, P < 0.10). Congruently, carnitine supplementation improved the efficiency of nitrogen retention (P < 0. 05) and reduced urinary nitrogen excretion (14%, P < 0.10). Carcass fat content also was reduced in carnitine-supplemented pigs (P < 0. 10). Collectively, these data support the hypothesis that carnitine can improve the efficiency of nitrogen utilization in 20-kg pigs fed energy-limited, fat-containing diets. We conclude that endogenous carnitine biosynthesis may be adequate to maintain sufficient tissue levels during growth, but that supplemental dietary carnitine (at 500 mg/kg) may be retained sufficiently so as to alter nutrient partitioning and thus body composition of 20-kg pigs.
Heo
K
K
Departments of Animal Science, North Carolina State University, Raleigh, NC 27695-7621, USA.
Odle
J
J
Han
I K
IK
Cho
W
W
Seo
S
S
van Heugten
E
E
Pilkington
D H
DH
D000273:Adipose Tissue / Q000378:metabolism; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition; D002331:Carnitine / Q000378:metabolism / Q000494:pharmacology*; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D004044:Dietary Proteins / Q000378:metabolism; D019587:Dietary Supplements; D004734:Energy Metabolism; D009584:Nitrogen / Q000378:metabolism*; D013552:Swine / Q000254:growth & development* / Q000378:metabolism
D004041:Dietary Fats; D004044:Dietary Proteins; D009584:Nitrogen; D002331:Carnitine