Probiotics reduce stress-related inflammation and abnormal behaviors in humans and rodents via regulation of the microbiota-gut-brain axis. The objective of this study was to determine if probiotic, Bacillus subtilis, has similar functions in broiler chickens under heat stress (HS). Two hundred forty 1-d-old broiler chicks were assigned to 48 pens with 4 treatments: Thermoneutral (TN)-RD (regular diet), TN-PD (the regular diet mixed with 1 × 106 CFU/g feed probiotic), HS-RD and HS-PD. Probiotic (Sporulin) was fed from day 1; and HS at 32°C for 10 h daily was initiated at day 15. The data showed that final BW, average daily gain , and feed conversion efficiency were improved in PD groups as compared to RD groups regardless of the ambient temperature (P < 0.01). Heterophil to lymphocyte ratio was affected by treatment and its value was in the order of HS-RD > HS-PD > TN-RD > TN-PD birds (P < 0.01). Compared to TN birds, HS birds spent more time in wing spreading, panting, squatting close to the ground, drinking, sleeping, dozing, and sitting but spent less time in eating, standing, and walking (P < 0.05 or 0.01). In addition, HS birds had greater levels of hepatic IL-6, IL-10, heat shock protein (HSP)70, and HSP70 mRNA expression (P < 0.01) and greater levels of cecal IgA and IgY (P < 0.01) compared to TN birds. Within TN groups, TN-PD birds had greater concentrations of hepatic IL-10 (P < 0.05) and cecal IgA (P < 0.01) than TN-RD birds. Within HS groups, HS-PD birds spent less time in wing spreading, panting, squatting close to the ground, drinking, sleeping, dozing, and sitting but spent more time in eating, foraging, standing, and walking than HS-RD birds (P < 0.05 or 0.01). The HS-PD birds also had lower concentrations of hepatic IL-6 and HSP70 (P < 0.01), whereas greater levels of IL-10 (P < 0.05) and lower concentrations of cecal IgA and IgY (P < 0.01). These results indicate that broilers fed the probiotic, B. subtilis, are able to cope with HS more effectively by ameliorating heat-induced behavioral and inflammatory reactions through regulation of microbiota-modulated immunity.

After birth, piglets undergo procedures likely to cause stress. The aim of this study was to evaluate stress responses evoked by 2 combinations (More Stressful [all a] or Less Stressful [all a] or More Stressful [all b]) of alternative methods for performing the following processing procedures: 1) teeth resection (TR) – [a] clip vs. [b] grind; 2) identification (ID) – [a] ear tag vs. [b] ear notch; 3)iron administration (FE) – [a] inject vs. [b] oral; 4) castration (CA) – [a] cords cut vs. [b] cords torn; 5) taildocking (TD) – [a] cold clip vs. [b] hot clip [corrected]. Ten litters of eight 2- and 3-d-old piglets were assigned to each procedure. Within each litter 1 male and 1 female piglet was assigned to 1 of 4 possible procedures: the 2 combinations, sham procedures, and sham procedures plus blood sampling. Blood was collected before processing and at 45 min, 4 h, 48 h, 1 wk, and 2 wk afterward and assayed for cortisol and β-endorphin concentrations. Procedures were videotaped and analyzed to evaluate the time taken to perform the procedure and the number of squeals, grunts, and escape attempts. Vocalizations were analyzed to determine mean and peak frequencies and duration. Piglets were weighed before the procedure and at 24 h, 48 h, 1 wk, and 2 wk afterward. Identification, tail docking, and castration lesions were scored on a 0 to 5 scale at 24 h, 1 wk, and 2 wk postprocedure. Both combinations of methods took longer to carry out than sham procedures and resulted in more squeals, grunts, and escape attempts during the procedures and higher peak frequencies of vocalizations compared with the control treatments (P < 0.05). Cortisol concentrations 45 min after processing were also higher in the 2 combination treatments than in the sham treatments (P < 0.05). Comparing between procedure treatments, the More Stressful combination of methods took longer to carry out, resulted in higher β-endorphin concentrations at 1 wk, had higher peak frequency of vocalizations, and increased ear (P < 0.05) and tail wound (P < 0.1) lesion scores at 1 wk than the Less Stressful combination. Growth during d 2 to 7 postprocedure was lower in More Stressful piglets than control piglets (P < 0.05) but by 2 wk, growth was unaffected. Using measures of behavior, physiology, and productivity, the More Stressful combination of procedures decreased welfare relative to the Less Stressful combination; however, both combinations decreased welfare relative to controls. The time taken to carry out the procedure would appear to be an important factor in the strength of the stress response.

This study examined the effects of a dietary synbiotic supplement on the behavioral patterns and growth performance of broiler chickens exposed to heat stress (HS). Three hundred sixty 1-day-old male Ross 708 broiler chicks were distributed among 24 floor pens (15 chicks per pen); each pen was randomly assigned to one of 3 dietary treatments containing a synbiotic at 0 (control), 0.5 (0.5X) and 1.0 (1.0X) g/kg. From d 15 to 42, birds were exposed to HS at 32°C daily from 08:00 to 17:00. Five broiler chickens were randomly marked in each pen for behavioral observation. Instantaneous scan sampling was used to record the birds' behavioral patterns. Performance parameters were measured on d 7, 14, 28 and 42. The synbiotic fed birds exhibited more standing, sitting, walking, feeding, preening and less wing spreading and panting behaviors (P < 0.05) compared to birds fed the control diet. The synbiotic group also had higher BW, BW gain and feed intake on d 7, 14 and 42 (P < 0.05), and higher BW, feed intake and feed conversion ratio at d 28 (P < 0.01). There were no treatment effects on drinking behavior, BW gain on d 28 and feed conversion ratio on d 42 (P > 0.05). There were few dose-related differences of the synbiotic on production performance; namely, the 1.0X concentration resulted in the highest BW and feed intake on d 14 and 42 (P < 0.05), while BW gain was higher compared to the control group only on d 42 (P < 0.05). The results suggest that the synbiotic supplement may prove to be an important management tool for the broiler industry to diminish the negative effects of HS, potentially safeguarding the welfare and production of broiler chickens, particularly in areas that experience hot climates.

This study examined effect of a dietary synbiotic supplement on the concentrations of plasma thyroid hormones, expressions of heat shock protein 70 (HSP70), and intestinal histomorphology in broiler chickens exposed to cyclic heat stress (HS). Three hundred and sixty day old male Ross 708 broiler chicks were randomly distributed among 3 dietary treatments containing a synbiotic (PoultryStar me US ) at 0 (control), 0.5 (0.5×), and 1.0 (1.0×) g/kg. Each treatment contained 8 replicates of 15 birds each housed in floor pens in a temperature and lighting controlled room. Heat stimulation was established from days 15 to 42 at 32°C for 9 h daily. The results indicated that under the HS condition, both synbiotic fed groups had lower liver and hypothalamus HSP70 levels ( P < 0.001) compared to control group; however, HSP70 mRNA expression was not different among treatments ( P > 0.05). There were no treatment effects on the levels of triiodothyronine (T 3 ) and thyroxine (T 4 ) as well as T 3 /T 4 ratio ( P > 0.05). Compared to controls, 1.0× HS broilers had greater villus height in the duodenum ( P < 0.01), and greater villus height and villus height:crypt depth ratios in the ileum ( P < 0.01). There were no differences among treatments on the measured intestinal parameters in the jejunum ( P > 0.05). The results suggest that the synbiotic may ameliorate the negative effects of HS on chicken health as indicated by the changes in the intestinal architecture and the levels of HSP70. Dietary synbiotic supplement could be a feasible nutritive strategy for the poultry industry to improve the health and welfare of chickens when exposed to hot environmental temperature.

The aim of this study was to determine the impact of probiotic feeding and chronic heat stress on meat quality, total lipid and phospholipid contents, lipid oxidation, antioxidant capacity, and heat shock protein abundance of broiler breast muscle. A total of 240 male broilers (5 birds per pen) were subjected to 4 treatments consisting of a 2 × 2 factorial design. Broilers were kept at 21-32-21°C for 10 h daily (heat stress, HS) or 21°C (thermoneutral condition) and fed a regular diet or the diet mixed with probiotic (250 ppm of Sporulin containing 3 strains of Bacillus subtilis). A total of 48 broilers (12 birds/treatment) were harvested at 46 d. Neither HS nor probiotic had substantial impacts on water-holding capacity, shear force, and color characteristics. HS induced lipid oxidation as increased 2-thiobarbituric acid reactive substances (TBARS), in which probiotic feeding decreased TBARS value (P = 0.002) and phospholipid contents (P = 0.0033) in breast muscle of HS broilers. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was increased with HS (P < 0.0001), but no significant impact of probiotic supplementation was found. Neither probiotic nor HS affected catalase activity, but superoxide dismutase and glutathione peroxidase activities were lower in HS broilers compared to thermoneutral controls (P < 0.0001) and in probiotics-fed broilers (P < 0.0001) compared to their counterparts. In addition, a significant interaction between probiotic and HS was found at glutathione peroxidase activities, in which breast muscle of broilers fed probiotic at thermoneutral condition showed the highest activity (P < 0.05). Regarding heat shock protein (HSP) determination, HS slightly increased the levels of both HSP70 (P = 0.08) and HSP27 (P = 0.05), but no significant impacts of probiotic supplementation were found. Our results indicate that probiotic feeding could improve breast muscle weight without adverse impacts on meat quality attributes, as well as alleviate oxidative deterioration of breast muscle of broilers undergoing heat stress.