Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 25, 2000
Publication Date: N/A
Interpretive Summary: A potent agonist of neurotransmitters is a compound called n-methyl-d, 1-aspartate (NMA). Neurotransmitters, also known as excitatory amino acids, have been shown to affect growth performance in avian species. The objective of this study was to determine whether feeding NMA to castrated male pigs would affect (improve) growth performance and carcass yield. Poor rfeed conversion efficiency and increased carcass fat was observed for pigs fed NMA. These negative effects on growth performance and carcass yield cast doubt on the potential use of NMA to enhance production performance and carcass leanness in swine.
We previously reported that broilers fed n-methyl-d, 1-aspartate (NMA), exhibited enhanced feed conversion efficiency and decreased percentage of fat in carcasses. In this experiment, growth performance and backfat thickness were evaluated in barrows fed NMA. Poland China x Yorkshire barrows weighing 68.8 kg (mean) were allowed ad libitum access to feed containing NMA at levels of either 0 (n=7), 100 (n=6), 200 (n=8), or 300 (n=8) ppm for 36 d. Barrows were slaughtered at 99.5 kg BW. There was no effect (P>.1) of NMA on ADG or feed consumption. Feed to gain ratio increased (P<.02) in a linear fashion with increasing level of NMA. There was a cubic effect (P<.05) of NMA treatment on first rib backfat thickness. In response to graded levels of NMA, backfat thickness at the tenth rib (P<.08) and last rib (P<.03) increased in a linear fashion. The NMA had no effect (P>.1) on backfat thickness measured at the lumbar vertebra or loin eye area measured at the tenth rib interface. In summary, NMA had an overall negative effect on growth performance and carcass yield characteristics in barrows. The dichotomous effects of NMA on feed efficiency and body composition in poultry and swine warrants further scrutiny.