Effects Of Oxygen Concentration And Probiotics On Broilers In High Altitude Region And Study Of Probiotics Alleviate Intestinal Inflammation Induced By Salmonella In Newly Hatched Chicks

More and more commercial broiler chickens are being raised in Tibet,China to meet the requirement for increased consumption.However,chickens reared in high altitude regions are burdened with a high mortality and low production performance,possibly due to poor immune response,oxygen stress and injured intestinal barrier induced by hypoxia,causing great economic losses to farmers.High altitude hypoxia refers to a state in which oxygen supply is insufficient.Enhancement of oxygen concentration of chicken house may alleviate the negative effects induced by hypoxia.Probiotics could modulate the immune response and improve intestinal barrier.Thus,one objective of this research is to study the effects of oxygen concentration and probiotics on chickens in high altitude region,and further research the mechanisms.It was demonstrated that a probiotic is more effective when chickens are under stress.Therefore,another objective of this study was to evaluate whether probiotics could alleviate the intestinal imflammation induced by Salmonella,this will provide theory basis for the application of this strain in chickens.Experiment 1.This first experiment was conducted to evaluate whether enhancement of oxygen concentration or administration of a potential probiotic could regulate immune response,improve production performance,and decrease mortality of chickens in high altitude region(LinZhi,Tibet,China,2,986 m above the sea level).A total of 360 1-d-old chickens were randomly allocated to 1 of 6 treatments in a 2×3 factorial arrangement.The first factor contained2 levels:low oxygen(the percentage of oxygen in chicken house was about 20.7%-21.4%)and high oxygen(the percentage of oxygen in chicken house was about 25.8%-26.5%),while the second factor was diet(basal diet,basal diet containing aureomycin at 50 mg/kg of diet,and basal diet plus 10~9 CFU/chick of Lactobacillus plantarum JM113(L.plantarum JM113)by oral gavage on the day of hatching).Red blood cell counts,hemoglobin level and hematocrit values of chickens in the high-oxygen house were significantly lower than chickens in the low-oxygen house on day 14.In comparison with chickens in low-oxygen house,enhancement of oxygen concentration significantly increased relative weights of thymus and spleen of chickens.The levels of immunoglobulin A(IgA),immunoglobulin G(IgG),interleutin-10(IL-10)and anti-BSA(Bovine Serum Albumin)antibodies of chickens in high-oxygen house were significantly higher,proinflmmatory cytokines interleutin-1beta(IL-1?)and lipopolysaccharide-induced tumor necrosis factor(LITAF)were significantly lower than that in low-oxygen house.In comparison with chickens in low-oxygen house,enhancement of oxygen concentration significantly reduced the mortality and increased the body weight(BW),average daily feed intake(ADFI).L.plantarum JM113 significantly increased the levels of IgA and anti-BSA antibodies.Moreover,L.plantarum JM113 significantly decreased the levels of IL-1?,LITAF and increased IL-10 compared with the control group.However,L.plantarum JM113 had no effect on the production performance of broilers.In the low-oxygen house,L.plantarum JM113significantly decreased the mortality of chickens compared with the other 2 groups,but it had no effect on the mortality of chickens in high-oxygen house.These results demonstrated that enhancement of oxygen concentration or administration of L.plantarum JM113 could improve immune response and reduce mortality of chickens reared in high altitude region.In addition,enhancement of oxygen concentration could also improve the production performance.Experiment 2.The second experiment was designed to research whether the improved production performance and decreased mortality by enhancement of oxygen concentration and administration of probiotic are associated with the improvement of oxygen stress and intestinal barrier of chickens reared in LinZhi.A total of 540 1-d-old chickens were randomly allocated to 1 of 6 treatments in a 2×3 factorial arrangement.The first factor contained 2 levels:low oxygen(the percentage of oxygen in chicken house was about 20.5%-21.0%)and high oxygen(the percentage of oxygen in chicken house was about 25.6%-26.2%).The second factor was diet(basal diet,basal diet containing Enterococcus.feacium JM23(E.faecium JM23)and basal diet containing L.plantarum JM113).In comparision with chickens in low-oxygen house,enhancement of oxygen concentration significantly decreased the level of malonaldehyde(MDA)and increased the levels of total anti-oxidative capacity(T-AOC)and total superoxide dismutase(T-SOD)in serum.In addition,the intestinal permeability and the levels of LITAF and IL-1?of chickens in high-oxygen house was lower,the expressions of tight junction genes ZO-1 and occludin were higher than chickens in low-oxygen house.However,the expression of claudin-1 and the level of interleutin-6(IL-6)in serum were not affected.The mortality of chickens in high-oxygen house was lower,the production performance and the height of villus were higher than chickens in low-oxygen house.In low-oxygen house,L.plantarum JM113could reduce the mortality and regulate the change of intestinal permeability,LITAF,IL-1?,occludin,ZO-1,MDA and T-AOC of chickens induced by hypoxia.E.feacium JM23 had no effect on these changes.L.plantarum JM113 and E.feacium JM23 significantly improved the production performance and the height of villus both in low-oxygen house and high-oxygen house.Taken together,these results demonstrated that enhancement of oxygen concentration or administration of L.plantarum JM113 could improve production performance and decrease mortality by alleviation oxygen stress,improvement the intestinal barrier,modulating the levels of cytokines of broilers in high altitude.Experiment 3.The third experiment was further to investigate the effect of L.plantarum JM113 on the intestinal inflammation of chickens induced by Salmonella.L.plantarum JM113could inhibite the growth of Salmonella and reduce the invasion of Caco-2 cells by Salmonella in vitro,then experiment was conducted in vivo.Eigity 1-day-old chicks were randomly allocated to 4 treatments(i)NC(negative control);(ii)LAC(the L.plantarum JM113-treated group);(iii)SAL(the Salmonella-infected group),and(iv)LAC+SAL(the L.plantarum JM113-treated and Salmonella-infected group).Samples were collected after 8 hours.A small number of heterophils were found only in the SAL group.The inflammation score,crypt damage score and total score of chicks in SAL group were higher than NC group.L.plantarum JM113 pretreatment(LAC+SAL)significantly decreased the inflammation score and total score compared with the SAL group,but the crypt damage score was not affected by L.plantarum JM113.There was no significant difference in apoptosis rates at 8 hpi among the four groups.In comparison with the NC group,Salomonella infection(SAL)significantly increased the activities of inflammatory meditator myeloperoxidase(MPO),and proflammatory cytokines LITAF,IL-1?,IL-6.L.plantarum JM113 prevented the increasing of MPO,LITAF,IL-1?,IL-6 induced by Salmonella.These findings indicated that L.plantarum JM113 could protect chickens from Salmonella induced intestinal inflammation by regulating the levels of MPO and LITAF,IL-1?and IL-6.In conclusion,these results demonstrated that enhancement of oxygen concentration and administration of L.plantarum JM113 could modulate the immune responses,alleviate oxygen stress,improve the development of intestine and intestinal barrier,thus improve production performance and decrease mortality of chickens in high altitude region.Therefore,enhancement of oxygen concentration or administration of L.plantarum JM113 may be cost-effective measures to improve the production performance and health status of chickens in high altitude regions.In addition,L.plantarum JM113 could alleviate the intestinal inflammation induced by Salmonella in newly hatched chicks.