Interactive effects of dietary ractopamine HCl and L-carnitine on finishing pigs: I. Growth performance1,2

Abstract

A total of 2,152 pigs (C22 × 336 PIC) were used in 4 experiments to determine the interactive effects of dietary l-carnitine and ractopamine HCl (RAC) on finishing pig growth performance. All trials were arranged as factorial arrangements with main effects of l-carnitine (0, 25, or 50 mg/kg in Exp. 1 and 2 and 0 or 50 mg/kg in Exp. 3 and 4) and RAC (0, 5, or 10 mg/kg in Exp. 1 and 0 or 10 mg/kg in Exp. 2, 3, and 4). Dietary carnitine was fed from 38 to 109 kg (Exp. 1 and 3) or for the last 4 or 3 wk before slaughter (118 kg; Exp. 2 and 4, respectively). Ractopamine HCl was fed for 4 wk (Exp. 1, 2, and 3) or 3 wk (Exp. 4) before slaughter. Experiments 1 and 2 were conducted in university research facilities, and Exp. 3 and 4 were conducted in a commercial research facility. All diets were formulated to contain 1.00% total Lys during the last phase of each experiment. In all experiments, pigs fed RAC had increased (P < 0.05) ADG and G:F compared with pigs fed no RAC. Feeding l-carnitine before the RAC feeding period did not affect pig growth performance. In Exp. 1 and 2, l-carnitine did not affect ADG during the last 4 wk; however, in Exp. 2, G:F tended (quadratic; P = 0.07) to improve with increasing l-carnitine. In Exp. 3, l-carnitine × RAC interactions were observed (P < 0.04) for ADG and G:F. Both added l-carnitine and RAC improved performance, but the response was not additive. In Exp. 4, pigs fed l-carnitine had increased (P < 0.04) ADG (0.88 vs. 0.84 kg) and G:F (0.36 vs. 0.35) compared with pigs fed no l-carnitine, and the response was additive to that of RAC. Analysis of treatments common to all experiments showed that pigs fed RAC had increased (P < 0.01) ADG (1.03 vs. 0.93 kg) and G:F (0.40 vs. 0.35) compared with pigs fed no RAC. Pigs fed l-carnitine tended to have increased (P = 0.07) ADG (1.00 vs. 0.96 kg) and improved (P < 0.01) G:F (0.38 vs. 0.37) compared with pigs not fed l-carnitine. These results confirm that RAC improves growth performance of finishing pigs. Added l-carnitine improved growth performance of finishing pigs, and the greatest response was observed in Exp. 3 and 4, which were conducted in commercial research environments. These experiments imply that adding l-carnitine to a finishing diet does not enhance the growth effects of RAC and that effects of RAC and l-carnitine on ADG and G:F are independent.

Effect of carnitine supplementation on growth performance and economics in pigs fed high fat diet

“…Present results are in agreements with the report of James et al (2013) who observed 3.1% and 4.1% increase in ADG and FCE in finisher pigs by dietary inclusion of 50 mg of L-carnitine/kg compared to non-supplemented group. In contrary to present results, James et al (2014) observed no effect on ADG and gain: feed ratio by feeding L-carnitine at 50 mg/kg for pigs weighing 36 to 86 kg, respectively. The results revealed no differences (P>0.05) between treatments T1, T2 and T3 in related to weight gain and average daily gain for finisher pigs (Table 2).…”

Interactive effects of dietary ractopamine HCl and L-carnitine on finishing pigs: II. Carcass characteristics and meat quality1,2

“…Several studies have shown that pigs fed 10 mg/kg RAC have 6 to 16% less fat at the 10th rib than pigs not fed RAC (Apple et al, 2004a(Apple et al, , 2008Carr et al, 2005b). One item potentially explaining the variability in our results could be the difference in level of feed (energy) intake between the studies conducted with 2 pigs per pen compared with the pigs housed in the commercial facility (James et al, 2013). Pigs in Exp.…”

“…The pigs used in these experiments were part of a larger project (James et al, 2013) conducted to evaluate the interactive effects of dietary L-carnitine and RAC (Elanco Animal Health, Greenfield, IN) on growth performance of growing-finishing pigs. All pigs used in these experiments were progeny of C22 females × 336 boars (PIC, USA, Hendersonville, TN).…”

Effect of dietary supplementation with l-carnitine, chromium, and selenium on the performance of finishing pigs

“…The inconsistent results for the use of L-carnitine can be attributed to several causes, such as the sanitary status; the age of the animals; and environmental, genetic, and nutritional factors (JAMES et al, 2013;RINCKER et al, 2003). In the present study, the dose of 50 mg L-carnitine kg -1 of feed was within the values commonly employed in experiments and commercial farming (HARMEYER, 2003;OWEN et al, 2001;RINGSEIS et al, 2018) and proved effective under the conditions of this test.…”

“…In biochemical processes, L-carnitine forms esters from long-chain fatty acids catalyzed by the enzyme carnitine palmitoyltransferase I (SASEENDRAN et al, 2017), which is able to penetrate the mitochondrial membrane (HEO et al, 2000;JAMES et al, 2013). These esters are then cleaved again through the action of carnitine palmitoyltransferase II and released within the mitochondria to be used for energy production (HEO et al, 2000).…”