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Piglets of low birth weight have a smaller number of skeletal muscle fibres than their heavier littermates at birth and throughout life, which is associated with impaired growth and a poor carcass and meat quality at market age. It has been showed that carnitine supplementation to piglets during the suckling period results in an increased total muscle fibre number at weaning in piglets of low birth weight. This study investigated whether this effect is maintained until market age and whether this would attenuate the negative consequences of low birth weight on carcass and meat quality. Using a split-plot design with litter as block, sex as whole plot and treatment as subplot, the effects of early-postnatal L -carnitine supplementation on female and castrated male piglets of low birth weight were investigated on a total of 56 German Landrace piglets from 14 litters. From days 7 to 27 of age piglets were orally supplemented once daily with 400 mg of L -carnitine dissolved in 1 ml of water or received an equal volume of water without carnitine. From weaning (day 28) until slaughter (day 166 of age) all pigs were fed standard diets.
At weaning, carnitine-supplemented pig showed a twofold increased concentration of free carnitine (P<0.001) and a lower concentration of non-esterified fatty acids (P<0.05) in blood plasma indicating that carnitine became bioavailable and increased fatty acid utilization during the period of supplementation. Growth performance was not influenced. Carcass weight, measures of meat yield and fat accretion, as well as body composition did not differ between treatments. No differences between control and carnitine-treated pigs in total fibre number (P=0.85) and fibre cross-sectional area (P=0.68) in m. semitendinosus (ST) measured at slaughter could be observed. The carnitine group tended to exhibit a smaller proportion of slow-twitch oxidative fibres (P=0.08), a greater proportion of fast-twitch glycolytic fibres (P=0.11), and increased specific lactate dehydrogenase activity (P=0.09) in ST indicating a more glycolytic muscle metabolism. Compared with the controls, a lower pH 24 value was observed (P=0.05) in ST muscle of carnitine-supplemented pigs, which – in castrates only – was associated with an increased drip loss (P<0.01). Meat quality traits in m. longissimus were not influenced by treatment.
In conclusion, the hypothesis that early-postnatal carnitine supplementation to piglets of low birth weight permanently increases myofibre number and improves later carcass and meat quality could not be confirmed by this experiment.
D. Lösel and C. Rehfeldt, 2013. Effects of L-carnitine supplementation to suckling piglets on carcass and meat quality at market age. Animal, 1-8 doi:10.1017/S1751731113000268