The effect of fetal pig size and stage of gestation on tissue fatty acid metabolism and profile

Abstract

The fetus requires an adequate supply of fatty acids for optimum growth and development. It has been hypothesized that reduced activity of enzymes of fatty acid metabolism could contribute to inadequate fetal growth. In a porcine model of differential fetal growth we examined heart and liver fatty acid synthase, D5-desaturase and D6-desaturase gene expression and measured hepatic fatty acid profile to assess long-chain polyunsaturated fatty acid status. On gestation days 45, 65 and 100 sows were killed and tissues extracted from an average-sized fetus and the smallest fetus from each litter. As early as day 45, considerable hepatic D5-and D6-desaturase was detected, and this expression significantly increased as gestation progressed. In contrast, cardiac desaturase expression remained stable with time. Fatty acid synthase expression was greatest at day 65 in the liver, but was not expressed in the heart. Overall, the smallest fetus did not exhibit reduced tissue D5-or D6-desaturase expression or compromised polyunsaturated fatty acid status at any stage. In fact, small fetuses expressed more cardiac D5-desaturase than their average-sized siblings, possibly in response to a stress to the heart. It is clear from this study that fatty acid metabolism changes markedly as gestation progresses, and reduced fatty acid supply does not cause inadequate growth in this porcine model of fetal development.

Dietary Arachidonate Differentially Alters Desaturase-Elongase Pathway Flux and Gene Expression in Liver and Intestine of Suckling Pigs,

“…In addition, liver mRNA abundance of FADS2, ELOVL5, and FADS1 precipitously dropped from d 0 to 4 and did not recover to the initial d 0 values throughout the first 16 d of life. These results are congruent with literature reports showing, first, that FADS2 and FADS1 increase in liver throughout gestation (27) and second, that many genes with metabolic involvement in pigs show a similar pattern of rapid decline following birth and rebound several weeks later (28,29). In fact, Clandinin et al (30) demonstrated developmental increases in the ability of pig fetuses to synthesize trienes, tetraenes, and penteanes from preterm (60 d gestation) to full-term.…”

Pre- and postnatal hepatic gene expression profiles of two pig breeds differing in body composition: insight into pathways of metabolic regulation

“…FASN expression was unregulated from 35 dpc to 63 dpc and downregulated from 63 dpc to peripubertal age; thus it was highest at 63 dpc. The prenatal regulation of expression of FASN in the liver and also of other genes encoding enzymes of the fatty acid metabolism as found here and in other studies (31) indicates that there are marked changes and suggests an important role of fatty acid metabolism during gestation. Indeed, deletion of FASN or ACACA in mice resulted in embryonic lethality, indicating that the de novo fatty acid synthesis is essential for embryonic development (30).…”

Effects of birth weight and maternal dietary fat source on the fatty acid profile of piglet tissue

“…These results suggest that the higher incidence of pre-weaning mortality in low birth weight piglets may be related to their lower brain DHA status, as supplementing the maternal diet with fish oil has already been shown to positively influence vitality (Rooke et al, 2001a and2001b;Capper et al, 2006). However, our results are in contrast to other studies, where piglet birth weight had no effect upon tissue FA composition (Rooke et al, 1999;McNeil et al, 2005;Sampels et al, 2011). It should be noted that the former two studies compared the lightest piglets per litter with piglets of average birth weight, and not with the heaviest piglets as in the current study.…”

“…Another explanation may be a reduced activity of enzymes involved in the FA metabolism. However, in a study by McNeil et al (2005) no Within diet, means without a common superscript letter differ, P < 0.05.…”