Metabolomic analysis of longissimus from underperforming piglets relative to piglets with normal preweaning growth

Background: Recent increases in intra-litter variability in weaning weight have raised swine production costs. A contributor to this variability is the normal birth weight pig that grows at a slower rate than littermates of similar birth weight. The goal of this study was to interrogate biochemical profiles manifested in skeletal muscle originating from slow growing(SG) and faster growing littermates(control), with the aim of identifying differences in metabolic pathway utilization between skeletal muscle of the SG pig relative to its littermates. Samples of longissimus muscle from littermate pairs of pigs were collected at 21 d of age for metabolomic analysis.Results: Birth weights did not differ between littermate pairs of SG and Control pigs(P > 0.05). Weaning weights differed by 1.51 ± 0.19 kg(P < 0.001). Random forest(RF) analysis was effective at segregating the metabolome of muscle samples by growth rate, resulting in a predictive accuracy of 81% versus random segregation(50%).Decreases in sugars in the pentose phosphate pathway(PPP) in the longissimus of SG pigs were detected(P < 0.05). Decreases were also apparent in glycolytic intermediates(glycerol-3-phosphate and lactate) and key glycolysis-derived intermediates(glucose-6-phosphate and fructose-6-phosphate; P < 0.05). SG pigs had increased levels of phospholipids, lysolipids, diacylglycerols, and sphingolipids(P < 0.05). Pathway analysis identified a cluster of molecules associated with muscle and collagen/extracellular matrix breakdown that are increased in the SG pig(glutamate, 3-methylhistidine and hydroxylated proline moieties; P < 0.05). Nicotinate metabolism was altered in SG pigs, resulting in a 78% decrease in the nicotinamide adenine dinucleotide pool(P < 0.05).Conclusions: These metabolomic data provide the first evidence for biochemical mechanisms that should be investigated to determine if they have a potential role in the slow growth in some normal birth weight piglets that contribute to increased intra-litter variability in weaning weights and provides essential information and potential targets for the development of nutritional intervention strategies.

Regulation of cytokine gene expression by orosomucoid in neonatal swine adipose tissue

Background： Porcine adipose tissue expresses orosomucoid（ORM1） mRNA, a protein with anti-inflammatory and immunomodulatory properties. Previous research has demonstrated that porcine ORM1 can reduce insulin stimulated glucose metabolism in porcine adipose tissue in vitro. The present study was designed to examine the preweaning ontogeny of ORM1 m RNA abundance in porcine subcutaneous adipose and to determine if ORM1 can regulate m RNA abundance of inflammatory cytokines that contribute to insulin resistance in primary cultures derived from neonatal porcine subcutaneous adipose tissue. Cultures were differentiated in vitro and subsequently the adipocyte containing cultures were incubated for 24 h with 0–5000 ng porcine ORM1/m L medium. Cultures were then harvested, total RNA extracted for use in reverse transcription and the m RNA abundance of cytokine m RNA quantified by real-time PCR.Results： ORM1 m RNA abundance within neonatal adipose tissue does not change from d 1 to d 21 of age and is a very small fraction relative to liver m RNA abundance. The ORM1 m RNA level in porcine adipocytes and stromalvascular cells are similar（P 〉 0.05）. Treatment with ORM1 did not affect TNFα（tumor necrosis factor α） m RNA level（P 〉 0.05）, while interleukin 6（IL6） m RNA abundance was reduced 32 % at 1,000 ng ORM1/m L（P 〈 0.01）. However,TNFα protein content in the cell culture media was reduced by ORM1 treatment（5,000 ng/m L, P 〈 0.05）, whereas ORM1 had no detectable effect on the media content of IL6（P 〉 0.05）. The reduction of macrophage migration inhibitory factor（MIF） m RNA abundance by ORM1 was dose dependent（P 〈 0.01）. Monocyte chemotactic protein（MCP） m RNA level was reduced 27 % by 1,000 ng ORM1/m L（P 〈 0.05）.Conclusions： The data suggest that ORM1 has limited effects TNFα, IL6, MIF or MCP expression at the concentrations tested. Secondly, these cytokines do not appear to contribute to the reported insulin resistance induced by ORM1 in porcine adipose tissue in vitro as an increase in the abundance of these inflammatory cytokines would be predicted during an insulin resistant state.