The present experiment was conducted to investigate the effect of heat stress (HS) and stocking density (SD) on growth performance, breast meat quality, and intestinal barrier function in broiler chickens. Experimental treatments included two different ambient temperatures (20 °C: thermoneutral conditions, or 27.8 °C: HS conditions) and two different SD (low: 9 birds/m² and high: 18 birds/m²) in a 2 × 2 factorial arrangement. A total of 1140 21-day-old broiler chickens were allotted 1 of 4 treatments with five replicates. At the end of the experiment (35 days of age), two birds per replicate were euthanized for sample collections. The results indicated no interactions between HS and SD for all measurements. For main effects, HS decreased (p < 0.05) the growth performance of broiler chickens. Similarly, high SD also decreased (p < 0.05) body weight gain and feed intake. HS decreased (p < 0.01) jejunal trans-epithelial electric resistance (TER), whereas high SD did not affect TER. Neither HS nor high SD affected jejunal tight junction-related gene expressions; however, high SD reduced (p < 0.05) occludin expression. In conclusion, HS and high SD are key environmental factors decreasing broiler performance; however, the interactive effects of HS and high SD are not significant under the current conditions.

The objective of the current experiment was to investigate the effect of stocking density and sex on growth performance, meat quality, and intestinal

The objective of this study was to investigate the effects of dietary Bacillus subtilis supplementation on growth performance, jejunal lesion scores, oocyst shedding, and cytokine and tight junction protein expression in broiler chickens infected with Eimeria maxima. A total of 196 male day-old Ross 708 broilers were given a nonexperimental diet until 14 D of age. Then, all chickens were randomly assigned to one of seven dietary treatments: 2 basal diets (CON and NC); CON + virginiamycin (AB1); CON + bacitracin methylene disalicylate (BMD; AB2); CON + B. subtilis 1781 (PB1); CON + B. subtilis 747 (PB2); or CON + B. subtilis 1781 + 747 (PB3). At day 21, all chickens except those in the CON group were orally inoculated with E. maxima oocysts. At 7 D after E. maxima infection, the body weight gains of chickens fed PB2 and PB3 increased (P = 0.032) as much as those in chickens fed AB2. The body weight gain and feed efficiency of chickens fed PB2 were significantly increased (P < 0.001), and PB2 chickens showed (P = 0.005) the lowest lesion scores after E. maxima infection. Chickens fed PB2 showed (P < 0.05) lower mRNA expression of IL-1β in infected chicken groups. Chickens in the AB1, AB2, PB1, PB2, and PB3 groups showed (P < 0.05) greater mRNA expression of junctional adhesion molecule 2 in jejunal tissue, whereas occludin expression increased (P < 0.05) in the jejunal tissue of chickens fed AB2 or PB2. Dietary B. subtilis supplementation significantly improved the growth performance of young chickens to a level comparable with that induced by virginiamycin or BMD without E. maxima infection. After infection with E. maxima, dietary virginiamycin and BMD significantly enhanced the epithelial barrier integrity, and the dietary B. subtilis 747 showed significantly enhanced growth performance, intestinal immunity, and epithelial barrier integrity. Together our results indicated that certain strains of B. subtilis provide beneficial effects on the growth of young broiler chickens and have the potential to replace antibiotic growth promoters.

The study was conducted to investigate the effects of different Eimeria inoculation doses on the growth performance, gut ecosystem, and body composition of broilers in floor pens for 35 days. A total of 750 15-day-old broilers were allocated to five experimental groups with six replicate pens. The five experimental groups included unchallenged control (CON); Eimeria dose 1 (ED1): E. acervulina: 31,250/E. maxima: 6250/E. tenella: 6250; Eimeria dose 2 (ED2): E. acervulina: 62,500/E. maxima: 12,500/E. tenella: 12,500; Eimeria dose 3 (ED3): E. acervulina: 125,000/E. maxima: 25,000/E. tenella: 25,000; and Eimeria dose 4 (ED4): E. acervulina: 250,000/E. maxima: 50,000/E. tenella: 50,000. On D 21, BW were linearly reduced by increased Eimeria inoculation doses (p < 0.01). On D 35, the Eimeria challenge groups had significantly lower BW compared to the CON group. Increased Eimeria inoculation doses linearly decreased crude fat (CF) (p < 0.01) on D 21. Increased Eimeria inoculation doses tended to increase the relative abundance of the phylum Proteobacteria (p = 0.098) on D 21. On D 35, lean:fat was linearly reduced by increased Eimeria inoculation doses (p < 0.05). Eimeria infection negatively influenced growth performance and gut health in broilers in the acute phase, and the negative effects were prolonged to D 35 in floor pen conditions.

Water-miscible vitamin E (WVE) has been known to be more bioavailable than conventional lipid-soluble vitamin E (LVE) in human foods because of its g

A study was conducted to investigate the effects of tannic acid (TA) supplementation on growth performance, gut health, antioxidant capacity, gut microbiota, and meat yield and quality in broilers raised for 42 days. A total of 700 one-day-old male broiler chickens (Cobb500) were allocated into 5 treatments with 7 replicates of 20 birds per pen. There were five treatments: 1) tannic acid 0 (TA0: basal diet without TA); 2) tannic acid 0.25 (TA0.25: basal diet+0.25 g/kg TA); 3) tannic acid 0.5 (TA0.5: basal diet+0.5 g/kg TA); 4) tannic acid 1 (TA1: basal diet+1 g/kg TA); and 5) tannic acid 2 (TA2: basal diet+2 g/kg TA). The dietary phases included starter (D 0 to 18; crumble feed), grower (D 18 to 28; pellet feed), and finisher (D 28 to 42; pellet feed). On D 18, the supplementation of TA linearly reduced body weight (BW) and average daily feed intake (ADFI) (p < 0.05), and on D 28, the supplementation of TA linearly reduced BW, average daily gain (ADG), and feed conversion ratio (FCR) (p < 0.05). Relative mRNA expression of genes related to mucin production (MUC2), tight junction proteins (CLDN2 and JAM2), and nutrient transporters (B0AT1 and SGLT1) was linearly increased by the supplementation of TA (p < 0.05). The supplementation of TA tended to linearly increase the relative abundance of the family Enterobacteriaceae (p = 0.08) and quadratically increased the relative abundance of the families Lachnospiraceae and Ruminococcaceae in the cecal microbial communities (p < 0.05). On D 36, the ratio of the phyla Firmicutes and Bacteroidetes was quadratically reduced by the supplementation of TA (p < 0.05). On D 42, bone mineral density and the lean to fat ratio were linearly decreased by the supplementation of TA (p < 0.05). On D 43, total chilled carcass weight was linearly reduced (p < 0.05), and proportion of leg weight was increased by supplementation of TA (p < 0.05). The supplementation of TA linearly reduced pH of the breast meat (p < 0.05) and linearly increased redness (a*) (p < 0.05). Although the supplementation of TA positively influenced gut health and gut microbiota in the starter/grower phases, it negatively affected overall growth performance, bone health, and meat production in broilers on D 42.