Effects of Conjugated Linoleic Acid. 1. Fatty Acid Modification of Yolks and Neonatal Fatty Acid Metabolism

Abstract

The purpose of this study was to evaluate the effects of conjugated linoleic acids (CLA) on neonatal fatty acid metabolism. In this study, layer hens (n = 40) were divided into four equal groups and subjected to the following treatments. Group A served as the control group, Group B received 1 g CLA every other day, Group C received 1 g CLA every 4th d, and Group D was sham-supplemented with 1 g safflower oil every other day. After 4 mo of feeding, Group B hens exhibited an increase in BW and egg size; however, there were no differences noted in feed consumption among the various treatment groups. At the same time, hens were inseminated with a constant dose of pooled rooster semen to evaluate changes in chick liver and yolk fatty acid metabolism during neonatal growth. At hatch and through 6 d of age, there were no significant differences in breakout data (fertility and numbers of early-, mid-, or late-dead chicks) or chick BW, respectively. However, Group B chicks exhibited an increase in liver 18:3n3 and 22:1n9 and a decrease in 20:3n6 and 22:5n3 fatty acids when compared with chicks from Groups A and D. Also noted for Group B chicks, yolk 18:0 fatty acid was higher than that for Group A and D chicks. These results suggest that CLA alters lipid metabolism in growing chicks.

Maternal dietary conjugated linoleic acid alters hepatic triacylglycerol and tissue fatty acids in hatched chicks

“…The carcass fat for CLA2 chicks was 26% less than Control chicks. Latour et al (16) reported an increase in the retention of remnant yolk in chicks hatched from eggs containing CLA. Inhibition of yolk fat absorption or transfer through the yolk sac or an increase in oxidation may contribute to the reduced fat accumulation in CLA1 and CLA2 chicks.…”

“…Transfer of lipids and fat-soluble nutrients from the egg yolk to the embryonic liver is accomplished by TAG-rich lipoproteins through the yolk sac membrane (24). The percentage of TAG in VLDL particles has been reported to be lower in chicks hatched from hens fed CLA (16). These researchers also observed a reduction in remnant yolk in the chicks hatched from hens fed CLA, suggesting that CLA enrichment in the yolk leads to either an impairment in yolk lipid removal or hepatic tissue TAG accretion during the incubation period.…”

“…Therefore, FA delivery, partitioning, and tissue uptake during incubation affects embryonic health and hatchability. Adverse effects of yolk CLA on hatchability (15), yolk absorption and reduction in chick VLDL TAG were reported (16). Because the CLA composition of egg yolk can be manipulated by diet, the CLA-modified egg is a useful research tool for studying the role of maternal dietary CLA on lipid metabolism in the progeny.…”

Conjugated linoleic acid

“…In the majority of the recent studies discussed here, the CLA used contained equivalent (or near equivalent) amounts of the 9-cis, 11-trans and 10-trans, 12-cis isomers, with minor (<2%) amounts of other positional or geometric isomers. Aydin et al (1999) showed that 0.5% (w/w of total diet) CLA is enough to induce 100% chick mortality, but this result was not confirmed by other studies (Latour et al, 2000). Further studies relating to CLA and eggs are concerned with the effects on the lipid composition of eggs as a food source, and on egg hatchability and therefore the efficiency of poultry meat production.…”

Egg yolk conjugated linoleic acid alters phospholipid molecular species in chick tissues

“…The reason for the reduction in hatchability in CLAenriched eggs is not clearly known. Recent research suggests that the increase in the yolk saturated-to-monounsaturated FA ratio observed in CLA-enriched eggs may contribute to embryonic mortality [13,14]. No attempt has been made to investigate the PL changes during embryogenesis in CLAenriched eggs.…”