effects of l-carnitine administration on growth performance

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384 C. ARSLAN et al. 2.4. Statistics The results were statistically analysed using t-test in SPSS (SPSS inc., 1993). Values were expressed as mean + standard error (Sx). 3. RESULTS AND DISCUSSION In both the starter and growth periods, L-<strong>carnitine</strong> <strong>administration</strong> did not affect live weight, live weight gain, feed consumption and feed conversion efficiency in ducks (Table II). Although, there were no statistical differences between the groups, live weight was found to be 8.1% higher in the <strong>carnitine</strong> group than in the control group. This situation might be related to the positive effect <strong>of</strong> L-<strong>carnitine</strong> on lipid and energy metabolism. Gropp et al. (1994) reported that dietary L-<strong>carnitine</strong> supplementation could improve fatty acid and energy utilization and, therefore, live weight gain and feed conversion efficiency may be improved in poultry. Live weight <strong>of</strong> 8 week old ducks was similar, according to the results <strong>of</strong> I˙s¸ gu¨ zar et al. (2002) for Turkish native ducks. The natural L-<strong>carnitine</strong> content <strong>of</strong> the starter and growth diets used in the study was calculated 12.8 and 6.8 mg/kg, respectively (Table I). Probably, these amounts <strong>of</strong> TABLE II Effect <strong>of</strong> <strong>carnitine</strong> <strong>administration</strong> on live weight, live weight gain, feed consumption and feed conversion efficiency in ducks (Means + Sx) 1 Age Control group Carnitine group Live weight [g] Hatching 46.4 + 0.4 46.6 + 0.4 2 weeks 180.8 + 10.5 220.7 + 9.6 4 weeks 506.5 + 26.5 628.0 + 17.9 6 weeks 1182 + 19.5 1251 + 22.3 8 weeks 1490 + 5.3 1621 + 11.7 Live weight gain [g/d] 2 weeks 10.4 + 0.3 12.4 + 0.7 4 weeks 23.3 + 1.1 29.1 + 1.0 6 weeks 48.2 + 0.5 44.5 + 0.6 8 weeks 22.0 + 1.0 26.5 + 1.9 0–8weeks 26.0+ 7.9 28.1 + 6.5 Feed consumption [g/d] 2 weeks 22.6 + 0.8 23.2 + 0.9 4 weeks 58.7 + 2.4 67.0 + 2.2 6 weeks 143.9 + 3.3 144.3 + 2.9 8 weeks 159.6 + 5.8 169.9 + 11.7 0 – 8 weeks (cumulative) 5386 + 136 5662 + 204 Feed conversion ratio [kg/kg] 2 weeks 2.19 + 0.1 1.88 + 0.1 4 weeks 2.53 + 0.0 2.31 + 0.1 6 weeks 2.98 + 0.1 3.24 + 0.0 8 weeks 7.27 + 0.2 6.48 + 0.3 0–8weeks 3.75+ 0.1 3.54 + 0.1 1 Hatching: n = 50; week 2: n = 48 and n = 49 for control and <strong>carnitine</strong> group, respectively; weeks 4 – 8: n = 48. Means are not significantly different (P 4 0.05).
L-<strong>carnitine</strong> and L-<strong>carnitine</strong> precursors (lysine and methionin) in the diet may be adequate for the ducks’ requirements. In a study conducted on fish, piglets and quail, Schumacher et al. (1993) concluded that L-<strong>carnitine</strong> seemed effective in improving body weight gain and feed conversion, mainly in groups with diets marginally in lysine and methionine plus cystine content, respectively. Average live weight gain during the whole experimental period can be calculated as 26.0 and 28.1 g in the control and in the <strong>carnitine</strong> group, respectively (Table II). Ducklings have shown very rapid live weight gain and better feed conversion efficiency in the first 6 week period, but after this period poor feed conversion efficiency has been observed because <strong>of</strong> slow live weight gain. The findings may be accepted as a criteria for determination <strong>of</strong> slaughter time in Turkish native ducks. L-<strong>carnitine</strong> <strong>administration</strong> did not affect feed consumption, which was 5386 and 5662 g in the control and in the <strong>carnitine</strong> groups, respectively, during the whole experimental period (Table II). Similar results were reported in previous research conducted on broilers (Mast et al., 2000; Lien and Horng, 2001; Buyse et al., 2001; C¸ elik and O¨ ztu¨ rkcan, 2003). The ducks supplied with L-<strong>carnitine</strong> via drinking water, consumed approximately the same amount <strong>of</strong> feed as the control ducks, but they gained more weight than the control group during the experimental period. Therefore, feed conversion efficiency was improved (not significant) in the <strong>carnitine</strong> group (Table II). Similar results were reported by other research (Barker and Sell, 1994; Mast et al., 2000; Lien and Horng, 2001; Buyse et al., 2001; Rodehutscord et al., 2002). As shown in Table III, L-<strong>carnitine</strong> had no significant effect on the examined carcass parameters. Carcass ratio was found to be 63.6 and 65.9% in the control and in the <strong>carnitine</strong> group, respectively. These values are slightly lower than those reported by I˙s¸ gu¨ zar et al. (2002) on Turkish native ducks. Ducks are characterized by the genetic predisposition to fat. The consumers usually prefer food with a low fat content. Abdominal fat weight could be used as a criteria for prediction <strong>of</strong> total body fat content <strong>of</strong> poultry (Sonaiya, 1985). From this point <strong>of</strong> view, L-<strong>carnitine</strong> <strong>administration</strong> tended to result in a leaner carcass with decreasing abdominal fat percentage, which was again not significant. This finding is in agreement with those <strong>of</strong> Rabie et al. (1997b), Rabie and Szilagyi (1998) and Buyse et al. (2001) on broiler chickens. Unchanged liver and TABLE III Carcass traits <strong>of</strong> ducks (Means + Sx, n = 25) Parameters Control group Carnitine group Live weight [ g ] 1653 + 10.4 1750 + 3.4 Carcass weight [ g ] 1053 + 7.2 1153 + 3.4 Carcass ratio [%] 63.6 + 0.7 65.9 + 0.9 Carcass parts [% <strong>of</strong> the carcass weight] Breast 16.6 + 0.4 19.0 + 0.9 Legs 26.9 + 0.4 25.8 + 0.6 Wings 14.9 + 0.4 15.2 + 0.5 Neck 12.7 + 0.4 10.1 + 0.5 Back 26.7 + 0.4 28.1 + 0.7 Heart 1.0 + 0.0 0.8 + 0.0 Liver 3.68 + 0.3 3.52 + 0.2 Mesenteric fat 0.68 + 0.0 0.32 + 0.0 Abdominal fat 1.46 + 0.3 1.02 + 0.1 Means are not significantly different (P 4 0.05). EFFECTS OF L-CARNITINE ON GROWTH 385
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