Effects Of Different Sources Of Protein Or Oil On Growth Performance, Immune Function And Intestinal Health Of Low Birth Weight Piglets After Weaning

Low birth weight piglets have low weaning weight and suffer growth check and health problems after weaning.In intensive system,the survival rate and growth performance of low-birth-weight piglets will be negatively affected the large-scale production,all-in-all-out and slaughter performance.Therefore,the nutritional strategy of low birth weight piglets needs to be studied.This study mainly investigated the influences of high quality proteins and fats such as plasma protein powder and flaxseed oil on growth performance,immune function and intestinal health of low birth weight piglets after weaning from the perspective of protein and fat sources.Experiment 1: Effects of protein sources on growth performance,immune function and intestinal health of low birth weight piglets after weaning.The purpose of this study is to explore the influence of Soybean protein concentrate(SPC)or sprain-dried plasma protein(SDPP)from two different sources on growth performance,oxidative stress,immune function and intestinal health of low-birthweight piglets after weaning.According to a 2×2 experimental design,18 Low Birth Weight piglets(LBW,1.09±0.01kg)and 18 Normal Birth Weight pigs(NBW,1.58 ±0.02kg)were selected and weaned at 23±1 day.They were fed diets containing 5% Soybean protein concentrate(SPC)or 4.18% Spray-dried plasma protein(SDPP)respectively after weaning.There were 9 replicates in each treatment,with one piglets per replicate.The trial lasted for 14 days.The results showed that the body weight,ADFI at different stages and whole peirod ADG of LBW piglets were significantly lower than those of NBW piglets(P < 0.05),and the relative weights of longissimus thoracis and psoas muscle reduced significantly(P< 0.05)after weaning.2 days after weaning,the contents of CREA and NEFA in plasma of LBW piglets increased significantly,while plasma growth hormone(GH)decreased significantly at weaning and 2 days after weaning(P < 0.05)and insulin-like growth factor-1(IGF-1)decreased significantly 7 days after weaning(P< 0.05).Meanwhile,immune function of piglets with low birth weight was impaired,The levels of CD3+,CD3+CD4+,CD3+CD8+,CD3+CD4+/CD3+CD8+ in peripheral blood T lymphocyte and C3 in plasma were significantly decreased(P < 0.05).LBW piglets were severely oxidized,SOD activity in plasma decreased significantly 7 days after weaning,and the content of MDA in plasma increased significantly 14 days after weaning.At the same time,the content of Prevotella Shan and Collins in colonic chyme was decreased(P < 0.05).However,dietary SDPP significantly increased ADG levels during the second week and the whole period of the experiment(P < 0.05),significantly reduced the diarrhea index(P < 0.05),and increased the relative weight of longissimus dorsi muscle and liver(p < 0.05).and increased the relative weight of longissimus thoracis and liver(P < 0.05).The contents of CREA and UREA in plasma of SDPP piglets decreased significantly 2 days after weaning(P < 0.05).Therefore,SDPP improved intestinal morphology and oxidative stress,increased the height of ileal villi and the activity of GSH-px in plasma significantly(P < 0.05).SDPP improved the structure of intestinal microbial flora and its metabolites of piglets,lactic acid bacillus and other bacteria in colonic chyme increased significantly(P < 0.05),while bacterium coli and bacteroid decreased significantly(P< 0.05),and the concentrations of acetic acid,propionic acid and butyric acid in colonic chyme increased(P < 0.05).Experiment 2: Effects of oil sources on growth performance,immune function and intestinal health of low birth weight piglets after weaning.Based on the frist experiment,The purpose of this experiment is to explore the influence of two different oils about Soybean Oil(SO)or Flaxseed Oil(FO)on the growth performance,immune function and intestinal health of low birth weight piglets after weaning.According to a 2×2 experimental design,40 LBW piglets(1.14±0.03 kg)and 40 NBW piglets(1.50±0.02 kg)were selected and weaned at 21±1 day,they were fed diets containing 4% Soybean Oil(SO)or 4% Flaxseed Oil(FO)respectively after weaning.There were 10 replicates in each treatment,with 2 piglets per replicate.The trial lasted for 21 days.The results showed that the body weight of LBW piglets was lower than that of NBW piglets at all stages after weaning.ADFI was decreased significantly in the third week of the experiment.ADFI tended to be decreased in the whole period of the experiment,and the relative weight of heart and liver increased significantly.The digestibility of crude protein,energy and dry matter of piglets decreased significantly,and the digestibility of feed was affected by low birth weight.At the same time,the ileal villus height of LBW piglets tended to decrease(P=0.087).However,feeding FO had no significant effect on the weight gain of piglets,but significantly reduced the diarrhea index of piglets in the second week,the third week and the whole period of the experiment(P < 0.05).Also,the content of Ig G in plasma and the proportion of CD3+CD8+ T lymphocyte subsets in peripheral blood of piglets were increased(P < 0.05),the content of IL-6 in ileum mucosa was decreased(P< 0.05),the expression of inflammatory related genes My D88,NF-kb,TNF-a and IL-10 in ileum tissue was decreased(P < 0.05),and the gene expression of tight junction protein Claudin-1 and ZO-1 was increased(P < 0.05).FO changes the proportion of fatty acids in intestinal mucosa,the contents of C18:3n3,C20:3n3,C22:6n3 and total n-3PUFA significantly increased,while the total n-6/n-3PUFA proportion decreased significantly(P < 0.05).The relative abundance of colonic actinomycetes was increased(p<0.05),the relative abundance of spirochetes was reduced(P<0.05),and the relative abundance of Bifidobacterium and Blautia was increased(P<0.05).In conclusion,low birth weight significantly reduced the weight,growth rate and nutrients digestibility of weaned piglets,increased oxidative stress and immunological impairments.Feeding SDPP could improve growth performance,diarrhea index,intestinal morphology,oxidative stress,intestinal microorganisms and volatile fatty acids in LBW piglets,Further research also found that FO could improve diarrhea index,intestinal inflammation and intestinal microorganisms in piglets,associating with increased expression of intestinal tight junction protein gene.