Effect of organic acid blend and prebiotic on growth performance gut histomorphometry, tibia bone characteristics, reactive oxygen species, microbial count and expression of HSP 70 in heat stressed broilers.

Abstract

This experiment was designed to study the effects of mannanoligosaccharide (MOS) and organic acid blend (OAB) supplementation individually and in combination on growth performance, relative organ weight, lymphoid organ weight, gut mucosal micrometry, intraepithelial lymphocyte count (IELs), histochemistry of goblet cells, tibia bone characteristics, serum biochemistry, small intestinal microbiota and expression of heat shock protein 70 (HSP 70) in Hubbard chicks. Two experiments were conducted to study the influence of these supplements on broilers, during the first trial, birds were reared in a thermoneutral zone whereas, in the second trial birds were exposed to cyclic heat stress. For conducting the first trial a total of 128 one day-old chicks were divided equally in four different groups with each group having 4 replicates. The number of birds per group were 32 whereas the number of birds per replicate were 8.The first group was kept as control (CONT) whereas, the second (MOSG) and third (OABG) groups were given MOS (2g / kg of feed) and OAB (3g / kg of feed), respectively. The fourth group (MOS+OAB) was given combination of MOS (2g / kg of feed) and OAB (3g / kg of feed). Birds were given ad-libitum feed and water throughout the experiment of 35 days. At the end of trial, two birds from each replicate were slaughtered for analysis of selected parameters. The results showed that live body weight, feed intake, feed conversion ratio, carcass weight and carcass yield were significantly higher (p < 0.05) in MOS+OAB compared to MOSG, OABG and CONT groups. It was also seen that the weight of liver, thymus, pancreas, bursa of Fabricius, heart, duodenum (empty), jejunum (empty) and ileum (empty) of birds that were from MOS+OAB was significantly higher (p<0.05) than the weight of the aforementioned organs from the other groups. Mucosal micrometry of small intestine revealed that in all segments of small intestine villus surface area (VSA) significantly increased (p<0.05) by dietary supplementations under study as birds from group MOS+OAB had significantly higher vi (p<0.05) values for VSA compared to birds of groups MOSG, OABG and CONT. There was no significance (p>0.05) in the number IELs in small intestine after feeding MOS and OAB alone and in combination in jejunum and ileum. However, in duodenum birds from all the three treatment groups had significantly less (p<0.05) number of IEL compared to the birds of CONT group. It was observed that in all the three segments of small intestine acidic goblet cells (AGC) and total goblet cells (TGC) increased significantly (p<0.05) in MOS+OAB, MOSG and OABG group birds compared to birds of CONT group. However, there was no significant difference (p>0.05) for AGC and TGC between birds of MOS+OAB and OABG group birds. Number of mixed goblet cells (MGC) increased significantly (p<0.05) in all segments of small intestine in birds of groups MOS+OAB compared to MOSG, OABG and CONT group birds. Tibia bone analysis revealed that robusticity and tibiotarsal indices were significantly better (p < 0.05) for the birds fed combination of MOS and OAB. Serum biochemistry revealed that the values for total oxidant status (TOS), total antioxidant status (TAS), ceruloplasmin, arylesterase, paraoxonase, triiodothyronine (T3) and thyroxine (T4) were not significantly affected (p > 0.05) by single and combined supplementation of MOS and OAB. However, levels of TSH were significantly higher (p < 0.05) in birds of MOSG and OABG group birds compared to CONT. The results of microbial analysis showed higher number (p < 0.05) of lactic acid bacteria and yeast in birds having MOS+OAB in the contents of all small intestinal segments compared to other groups. It was observed that the level of HSP 70 was significantly decreased by supplementation of MOS and OAB. Results show that the concentration of HSP 70 in the mucosa of duodenum, jejunum and ileum was significantly lower (p<0.05) in birds of groups MOS+OAB, MOSG and OABG compared to CONT group. However, there was no significant difference (p>0.05) in expression of HSP 70 among birds of group MOSG, OABG and MOS+OAB. In conclusion, supplementation of MOS and OAB in combination is beneficial compared to their individual effects in broiler vii chicks. In second trial the birds were exposed to cyclic heat stress. To conduct this trial a total of 128 one day-old chicks were divided equally in four different groups with each group having 4 replicates. The number of birds per group were 32 whereas the number of birds per replicate were 8.The first group was kept as positive control (HSG) whereas, the second (HSMOS) and third (HSOAB) groups were given MOS (2g / kg of feed) and OAB (3g / kg of feed), respectively. The fourth group (HSMO) was given combination of MOS (2g / kg of feed) and OAB (3g / kg of feed). Birds were offered ad-libitum feed and water throughout the experiment of 35 days. At the end of the trial, two birds from each replicate were slaughtered for analysis of selected parameters. It was observed that the live body weight, feed intake, feed conversion ratio, carcass weight and carcass yield were significantly higher (p < 0.05) in HSMO compared to HSMOS, HSOAB and HSG. It was also seen that the weight of liver, thymus, pancreas, bursa of Fabricius, heart, duodenum (empty), jejunum (empty) and ileum (empty) of birds that were from HSMO was significantly higher (p < 0.05) than the weight of the aforementioned organs from the other groups. Mucosal micrometry of small intestine revealed that in all segments of the small intestine villus surface area (VSA) significantly increased (p < 0.05) by dietary supplementations under study as birds from group HSMO had significantly higher (p < 0.05) values for VSA compared to birds of groups HSMOS, HSOAB and HSG. It was found that the number IELs in all segments of the small intestine after feeding MOS and OAB alone and in combination significantly decreased (p < 0.05) in all the treatment groups compared to HSG. We also observed that in all three segments of small intestine AGC, MGC and TGC increased significantly (p < 0.05) in HSMO, HSMOS and HSOAB birds compared to birds of HSG. However, there was no significant difference (p > 0.05) for AGC, MGC and TGC between birds of HSMOS and HSOAB birds. Results of tibia bone analysis revealed that robusticity and tibiotarsal indices were significantly better (p < 0.05) for the birds fed combination of MOS and OAB. It was observed that the values for viii ceruloplasmin, arylesterase, paraoxonase and T3 were not significantly affected (p > 0.05) by single and combined supplementation of MOS and OAB. However, values for TOS and TAS were significantly lower (p > 0.05) in all the treatment groups compared to HSG. Levels of TSH and T4 were significantly higher (p < 0.05) in birds of HSMOS and HSOAB birds compared to HSG. Furthermore it was also observed that in HSMO TSH values were significantly higher (p < 0.05) than the birds from other three groups. It was seen that in all the three segments of small intestine acidic goblet cells (AGC) mixed goblet cells (MGC) and total goblet cells (TGC) increased significantly (p<0.05) in HSMO, HSMOS and HSOAB birds compared to birds of HSG. However, there was no significant difference (p>0.05) for AGC, MGC and TGC between birds of HSMOS and HSOAB birds. Regarding small intestine microbiology we observed that in all the small intestinal segments the total number of LAB increased significantly (p<0.05) by supplementation of MOS and OAB alone and in combination. It was observed that birds from group HSMO had significantly higher (p<0.05) LAB number followed by HSMOS birds and HSOAB birds compared to the birds of HSG. It was observed that the expression of HSP 70 was significantly decreased by supplementation of MOS and OAB. Results revealed that the concentration of HSP 70 in the mucosa of duodenum, jejunum and ileum was significantly lower (p < 0.05) in birds of groups HSMO, HSMOS and HSOAB compared to HSG. However, there was no significant difference (p > 0.05) in expression of HSP 70 among birds of group HSMOS, HSOAB and HSMO. It was concluded that for broilers reared under thermoneutral zone or cyclic heat stress supplementation of MOS and OAB in combination is more beneficial compared to their individual effects.