Influence Of Immune Challenge On Whole-Body Protein Turnover In Weanling Pigs

The objective of this study was to investigate the effects of immune challenge on protein metabolism and protein turnover by lipopolysaccaride-induced immune challenge and 15N?Glycine single-dose urine end-product method.It is a single-factor design,that is, it consists of three treatments: control, LPS-challenged and pair-fed.The pair-fed received the same amount of feed as the LPS-challenged. Weanling pigs were either intramuscular injection with Escherichia colt lipopolysaccharide (LPS,200 u g/kgBW) or with sterile saline(0.90%NaCl). Fifteen Landrace X Rongchang crossbred weanling pigs (initial body weight 10.15+0.39kg) were allotted to three treatments consisting of 5 pigs each. An experimental diet was formulated to contain CP20%, DE14.2MJ/kg, based on corn-soybean. It was 4 days metabolism experiment. All the piglets were given the N15-Glycine at the third day of the metabolism experiment. It should collect the urine of piglets 48 hours after given the Nl5-Glycine, then analyse the N15 of the urine. The protein turnover, protein synthesis, protein breakdown and protein retention were calculated by two-pool model method.Results indicate that immune challenge affect weanling pigs growth performance. Injection of LPS tended to reduce feed 28%(p<0.01), daily gain 43%(p<0.01) and feed efficiency 21%(p<0.01) compared to control pigs. Although LPS-challenged and pair-fed pigs had the same amount of feed intake,the daily gain decreased 14%(p>0.05), the feed efficiencies decreased 14% of LPS-challenge compared to pair-fed(p<0.01).Among them, 65% was decreased by feed intake and 33% was decreased by feed efficiency.Results indicate that immune challenge decrease the protein availability of weanling pigs . Compared to control,nitrogen intake,apparent nitrogen digestion and nitrogen retention are decreased by LPS-challenged pigs (p<0.01).Fecal nitrogen increased 31 %(p<0.05),the ratio of fecal nitrogen to nitrogen intake increased 32%(p<0.01), apparent nitrogen digestion decreased 9%(p<0.01) and total nitrogen availability decreased 14%(p<0.01) of LPS-challenge compared to pair-fed.Results indicate that immune challenge alter the protein turnover of weanling pigs. Nitrogen flux, protein synthesis and protein breakdown in the whole-body of weanling pigs decreased of LPS-challenged compared to control pigs(p<0.01).Regardless of the effect of feed intake, LPS- challenged pigs increased protein breakdown (p<0.01) while the nitrogenflux and protein synthesis were not affect evidently (p>0.05).According to the results, immune challenge decrease weanling pigs feed intake and feed efficiency evidently so that the growth performance of weanling pigs are decreased.Immune challenge increase the protein turnover rate,increase protein breakdown and decrease protein and energy availability.