Effects Of Selenium-Enriched Probiotics Dietary Supplementation On The Performance,Antioxidation Function And Intestinal Microbiota Of Piglets Under Hyperthermic Conditionts

Heat stress induced by high temperture has been a critical factor that affects the welfare and performance of farmed livestock negatively, which can dramatically alter the gastrointestinal microbial balance, decrease the immune functions and damage the antioxidant defense system of weaned piglets. The harmful effects of heat stress such as anorexia, lethargy, weight loss, feed utilization decreased and excess morbidity and mortality, which eventually cause a huge loss in the animal husbandry.Selenium (Se) is an essential trace nutrient element which plays an important role in host health and disease through some selenoproteins (including glutathione peroxidase (GPx) and iodotyrosine deiodinase). Its functions include improvig immunity and antioxidation, resisting tumor and regulating metabolism. Probiotics can maintain the balance of gastrointestinal micro flora, prevent pathogens from proliferating in the intestinal tract, alleviate intestinal inflammatory, improve the digestive system, and stimulate the immune system of the host. In order to minimize the harmful effects of heat stress on the piglet’s health and productive performance, the supplementation of probiotics and Selenium preparations have been used as anti-heat stress additives. Our lab have produced selenium-enriched probiotics through transformation by muti-probiotics. Selenium-enriched probiotics comprise several probiotics strains, which combines the virtues of probiotics with the virtues of organic Se, can exert dual effects of organic Se and probiotics to consumers at the same time. In our previous studies, we have performed selenium-enriched probiotics (including yeast and lactobacilli) on different animal experiments and all have some positive effects:improve growth performance and anoxidantion capacity, change the structure of gastrointestinal microbiota, but we did not do the experiment about anti-heat stress of selenium-enriched probiotics.The objective of this study is to evaluate the efficacy of selenium-enriched probiotics preparation on the growth performance, whole blood selenium concentration, GPx activity, plasma thyroid hormones (T3, T4) and intestinal microbiota of weaned piglets under hyperthermic conditions. Its effects as anti-heat stress additive was evaluated, so that to provide a theoretical basis for application of Se-enriched probiotics in husbandry.Experiment1:Effects of selenium-enriched probiotics on the growth performance of piglets under hyperthermic conditionsForty eight weaned piglets (LandracexYorkshirexDuroc) were kept in12different pens at the age of28days. Per pen4pigs were kept as experimental unit and3replicate pens per treatment in this study. The feeding trial was lasted for42days. The average temperature was38℃for the first33days and42℃for the last9days. This experiment was carried out to compare four treatments:control—basal diet; probiotics—basal diet plus0.3mg/kg probiotics (Lactobacillus and Saccharomyces); Sodium selenium (SS)—basal diet plus0.3mg/kg sodium selenium; Selenium-enriched probiotics (SP)—basal diet plus0.3mg/kg selenium-enriched probiotics (the number of live organism is equivalent). The basal diets of each dietary treatment contained0.16mg/kg supplemental selenium. The selenium supplements elevated the total dietary selenium level to0.46mg/kg. Results:The final BW (Body Weight) of piglets fed with SP, SS and P supplementation were15.35%(P<0.05),6.63%(P>0.05) and6.85%(P>0.05) higher than C diet, respectively. The ADG (Average Daily Gain) of piglets fed with SP, SS and P supplementation were22.58%(P<0.05),9.87%(P<0.05) and10.32%(P<0.05) higher than C diet, respectively. Piglets fed with SP diet has greater ADG than SS and P diet (P<0.05). Piglets fed with SP diet has lower F/G (Feed/Gain) ratio than those which were fed with SS, P and C diet (P<0.05), Piglets fed with SS and P diet has lower F/G (Feed/Gain) ratio than those which were fed with C diet (P<0.05). Piglets fed with SP and P diet has lower diarrhea incidence than those fed with SS and C diet (P<0.05), there were no significant differences between SP and P diet. Conclusions:Selenium-enriched probiotics supplementation could significantly enhance growth peforamce, decrease the diarrhea incidence of weaned piglets under hyperthermic conditions.Experiment2:Effects of selenium-enriched probiotics on the blood Se concentration, GPx activity and thyroid hormones (T3, T4) concentration of piglets under hyperthermic conditionsExperiment design is the same as the experiment1. Blood samples were collected in10mL heparinized tubes from the abdominal aorta of piglets for analysis of whole blood selenium (Se) concentration, glutathione peroxidase (GPx) activity and plasma thyroid hormones (T3, T4) on days0,14,28and42of the experiment. Results:The activity of blood GPx (P<0.05) and Se (P<0.05) concentration is also increased in all the SP and SS supplemented diets groups as compare to control groups, SP diet is higher than SS diet(P<0.05). The concentration of T3were increased (P<0.05) and T4were decreased (P<0.05) significantly in the serum of piglets which were fed with the supplementation of SP and SS as compare to the C diet and those provided the P diet on day28and42. There were no differences between SP diet and SS diet. Conclusions:Selenium-enriched probiotics and SS supplementation could signinificantly increase blood Se concentration, improve antioxidation function, increase plasma T3concentration and decrease T4concentration in weaned piglets under hyperthermic conditions.Experiment3:Effects of selenium-enriched probiotics on the intestinal micro flora of piglets under hyperthermic conditionsExperiment design is the same as the experiment1. To investigate the effects of selenium-enriched probiotics on the intestinal microflora of weaned piglets under heat stress conditions. Fresh fecal samples were collected aseptically from3pigs of each group on days0,14,28,42of the experiment for counting the amount Escherichia coli, Lactobacillus, Bifidobacterium, Staphylococcus and Enterococcu in the feces. Results:The amount of Lactobacillus were increased while the Escherichia coli were decreased significantly (P<0.01) in the feces of those piglets which were fed with supplementation of SP and P as compare to those which were fed the control diet on day28and42, while there were no differences between SS and C diet (P>0.05). There were no differences found in Staphylococcus, Bifidobacterium and Enterococcu among all the groups (P>0.05) during the experimental period. Conclusions:Selenium-enriched probiotics supplementation could regulate the ratio of beneficial bacteria and harmful bacteria and maintain the microbial balance in the gastrointestinal environment of piglets under hyperthermic conditions.Experiment4:Effects of selenium-enriched probiotics on the microbiota biodiversity of piglets under hyperthermic conditionsExperiment design is the same as the experiment1. Fresh fecal samples were collected aseptically from4pigs of each group on days42of the experiment and were analysised using the RFLP method. The PCR-amplified V3, V4and V5regions of the16S rDNA were digested by Hha I, Afa I, Alu I and Msp I, respectively. The degree of microbial biodiversity was measured as the total number of different bands obtained from the4independent restriction digestions. Results:Compared with the C diet, the total number of bands of SP diet and P diet were increased significantly than piglets fed with SS diet and C diet (P<0.05), there were no differences between SS diet and C diet (P>0.05). Compared with the C diet, similarities between RFLP profiles from fecal bacteria of SP diet, SS diet, P diet were65.0%,74.6%and68.1%, respectively. Conclusions:Selenium-enriched probiotics supplementation could increase the biodiversity of gastrointestinal microbiota.