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Title: Slow growing pre weaning piglets have altered adipokine gene expression

item Ramsay, Timothy
item Stoll, Margo
item Caperna, Thomas

Submitted to: Open Journal of Animal Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2014
Publication Date: 7/1/2014
Citation: Ramsay, T.G., Stoll, M.J., Caperna, T.J. 2014. Slow growing pre weaning piglets have altered adipokine gene expression. Open Journal of Animal Sciences. 4(7):187-195.

Interpretive Summary: Variability in growth rate in baby pigs results in litters of animals that are weaned at a great variety of body weights. This variability is an inherent inefficiency in swine production as the weaning weight has a direct impact on the efficiency of animal growth and lean meat deposition. Identification of the mechanisms that are responsible for this variability and the development of markers to reduce this variability in growth rate within a litter of pigs have a direct impact on the economics of swine production and agricultural efficiency. This study examined the gene expression for a number of genes that have been associated with the regulation of fat and muscle deposition between littermates who grew very fast or very slow. Hormones that are produced in body fat were found to be expressed at a lower level in slower growing pigs that are leaner with higher rates of lean deposition (leptin, adiponectin and tumor necrosis factor a). In contrast the cytokine interleukin 15 was found to be higher in the skeletal muscle of these same slow growing pigs with higher rates of lean deposition. This cytokine functions in muscle to enhance nutrient utilization for protein synthesis and energy metabolism. In addition, the enzyme lipoprotein lipase (necessary for fat uptake and utilization) was found to be lower in adipose tissue and higher in muscle from the slow growing, lean pigs. These data suggest these genes may be effective markers for identifying pigs that are more efficient at depositing protein and not fat. These data would suggest that these genes may be used to assist in enhancing selection for more uniform litter weights and improved efficiency of swine production, reducing the costs to the producer.

Technical Abstract: Pigs were selected from seven litters were monitored for growth rate from day 1 to 21. Samples of subcutaneous (SQ) and perirenal (PR) adipose tissues were collected at day 21 of age from the fastest and slowest growing piglets within the litter. Total RNA was extracted and reverse transcription and real-time PCR were used to quantify mRNA abundance for: leptin, adiponectin, interleukin 1ß (IL1ß), IL6, IL15, tumor necrosis factor a (TNFa), macrophage migration inhibitory factor (MIF), monocyte chemoattractant protein 1, insulin-like growth factor 1, fatty acid synthase and cyclophilin. Leptin, adiponectin, TNFa and LPL mRNA abundance was lower in slow growing piglets at d 21 of age in SQ than fast growing piglets (P < 0.05). MIF and TNFa gene expression were reduced in PR from slow growing piglets in comparison to fast growing piglets (P < 0.05). Interleukin 1ß, IL15 and LPL were increased in the longissimus muscle of slow growing pigs relative to fast growing piglets (P < 0.05). Analysis of the mRNA abundance for these adipokines within adipose tissue at d21 of age demonstrated that the effect of growth rate on adipokine expression varies among the different adipokines and the internal and external sites of adipose tissue deposition (PR versus SQ). In addition, the increase in skeletal muscle expression of LPL and IL15 suggests that partitioning of nutrients for energy use in protein synthesis may be greater in the skeletal muscle of the slower growing piglet.