| This experiment aimed to study the effects of adding sodium dichloroacetate(DCA)to low-protein diets on the growth performance,meat quality,nutrient metabolism and intestinal microflora of growing-finishing pigs.In the experiment,48 Duroc × Landrace× Yorkshire growing pigs(27 ± 0.4 kg)were used and allocated to 3 dietary treatments according to the principle of completely randomized blocks.One pig in a page was regarded as a replicate and each group had 16 replicates the animal experiment lasted 84 days and was divided into 3 stages.The diets in the three stages were: 18.0% CP(CON),13.5% CP(LP)and 13.5%CP +120 mg/kg DCA(LP + DCA)diets for the first stage(24 ~ 45 kg);16.5% CP(CON),12.0% CP(LP)and 12.0% CP +120 mg/kg DCA(LP + DCA)diets for the second stage(45 ~ 65 kg);15.5% CP(CON),11% CP(LP),and 11% CP +120 mg/kg DCA(LP + DCA)diets in the third stage(65 ~ 95 kg).During the experimental period,the feed intake of animals was recorded and all the animals were weighed on d 29,57,and 85.At the end of the experiment,6 pigs in each group were randomly selected to collect blood samples and were slaughtered to collect chyme,gastrointestinal tissue,muscle for the analysis of intestinal microflora,immune indices,material metabolism,meat quality.Experimental result 1: Effects of supplementing low-protein diets with DCA on the performance,carcass traits and meat quality in growing-finishing pigsCompared with the CON group,the average daily protein intake of pigs in the LP group was significantly reduced(P < 0.05).Compared with the LP groups,the average daily gain of pigs in the LP +DCA group were significantly increased(P < 0.05),whilst the feed-to-weight ratio were significantly reduced(P < 0.05).The final weight of pigs in LP + DCA group was significantly higher than that in LP group(P < 0.05).The organ weight,organ index,amino acid composition,shear force,drip loss,intermuscular fat and water content of the longissimus muscle were not significantly different among the three groups(P > 0.05).The trans-9-octadecenoic acid concentration of the longissimus dorsi muscle of pigs in the LP + DCA group was higher than that in the CON and LP groups(P < 0.05).Experimental result 2: Effects of supplementing low-protein diets with DCA on nutrient metabolism in growing-finishing pigsCompared with the CON group,the concentrations of plasma high-density lipoprotein,triglycerides,total cholesterol and alkaline phosphatase in the LP group were significantly increased(P < 0.05),and the concentrations of plasma urea nitrogen and total bile acid were significantly reduced(P < 0.05).In LP group,the concentrations of plasma insulin,thyroid hormone,triiodothyronine,growth hormone and leptin and the relative protein expression of p-AMPK in jejunal mucosa and liver tissues of pigs were significantly higher than the other two groups(P < 0.05).The concentration of plasma melani as well as,the relative protein expression of SIRT1 in jejunal mucosa and liver tissue of pigs feeding with the LP diet were significantly reduced than with the CON diet(P < 0.05),while the activities of 3-hydroxy-3-methylglutaryl-Co A reductase and cholesterol 7α Hydroxylase did not change significantly(P > 0.05).The LP + DCA group significantly increased the concentrations of high-density lipoprotein,triglycerides,total cholesterol and urea nitrogen in the plasma and reduced the concentrations of insulin,thyroid hormone,triiodothyronine,growth hormone and leptin of pigs compared with the CON group(P < 0.05).Compared with the LP group,the concentration of plasma urea nitrogen,the relative protein expression of AMPK protein in jejunum mucosa,SIRT1 protein in jejunum mucosa and liver tissue as well as PPARα in liver tissue of LP + DCA group were significantly increased(P < 0.05),while the concentration of the activity of alkaline phosphatase and the relative protein expression of p-AMPK protein in jejunum mucosa and liver tissue of the LP + DCA group was significantly reduced(P < 0.05).Moreover,LP + DCA group had lower3-hydroxy-3-methylglutaryl-Co A reductase and higher cholesterol 7α hydroxylase concentrations in the liver of pigs than the other two groups(P < 0.05).Experimental Result 3: Effects of supplementing low-protein diets with DCA on the intestinal microbial diversity and immune indexes of growing-finishing pigsCompared with the CON group,the concentrations of plasma albumin of pigs in the LP group were significantly increased(P < 0.05),whilst the concentrations of total protein concentration,immunoglobulin Ig G and TLR4 protein in colonic mucosal were significantly reduced(P > 0.05).However,there was no significant difference between LP group and CON group in intestinal villi height,crypt depth and the ratio of villi height to crypt depth of pigs(P > 0.05).Compared with the LP group,the LP + DCA group showed increased concentrations of NF-κB protein and TLR4 protein in the colonic mucosa of pigs(P < 0.05),whereas the ratio of ileal villi height and crypt depth of pigs in the LP + DCA group was not significantly different from that in the LP group(P > 0.05).At the phylum level,Firmicutes showed highest relative abundance among the colonic microbes of pigs followed by Bacteroides,Proteobacteria,Spirochetes and Actinomycetes.The relative abundance of Kiritimatiellaeota in the colon of pigs feeding with the LP + DCA diet was significantly higher than that of pigs with CON and LP diets(P < 0.05).At the genus level,Streptococcus suis showed highest relative abundance compared with the other microbiota.The LP group showed higher relative abundance of Lacetospirillum and Prevotella in the colon of pigs than the CON group(P < 0.05).In summary,the addition of DCA to low-protein diets improved the growth performance as well as the abundance of beneficial bacteria in colonic microbes of pigs.DCA improved nutrient metabolism by regulating the AMPK pathway in the intestine and liver,and inhibited intestinal inflammation by regulating the NF-κB pathway which was beneficial for the intestinal health of pigs. |
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