Bacteriophages (BP) are viruses that invade bacteria and propagate inside them, leading to the lysis of the bacterial cells. The aim of this study was to investigate the effect of adding BP to the broiler’s diet and its effect on the performance, morphology and bacterial population of the gut, some immune responses and expression of some intestinal genes. Accordingly, dietary treatments were as follows: basal diet (control), and control + 0.3 g/kg colistin or 0.5, 1 and 1.5 g BP/kg of diet. BP increased the body weight gain and reduced the feed conversion ratio (FCR), as compared to the colistin treatment, in the finisher and overall period (P < 0.05). European efficiency factor was significantly higher in 1.5 g BP-fed birds, as compared to the control and colistin treatments. meanwhile, bacteriophage and colistin-fed birds had higherLactobacillusand lowered coliform bacteria counts, as compared to the control treatment (P < 0.05). Cecal concentrations of propionate in the 1.5 g BP-fed birds were higher than those in the control treatment (P < 0.05). BP-fed birds had a significantly increased villus height to crypt depth ratio, as compared to the control treatment. BP increased the serum concentrations of the total antibody, immunoglobulin (Ig) M, and IgG, as compared to the control treatment (P < 0.05). In the ileum, the expression of the Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) gene was decreased by dietary BP supplementation (P < 0.05). Furthermore, Toll-like receptor 4 (TLR4) gene expression was down-regulated in the BP-fed birds, whereas Interleukin 10 (IL-10) gene expression was up-regulated (P < 0.05). Overall, the use of BP may be a promising alternative to growth-promoting antibiotics in broilers by altering the gastrointestinal tract microbiota, enhancing immunological responses and improving the gut's morphology.

Bacteriophages (BP) are viruses that can infect bacteria. The present study evaluated the effect of BP on Salmonella infected broilers. A number of 150 day-old broilers were used in a completely randomized design with five treatments that included: (1) basal diet from day 0 to 28; (2) basal diet + 0.3 g/kg of colistin from day 0 to 28; (3) basal diet from day 1 to 13, and basal diet + 0.4 g/kg of colistin from day 14 to 28; (4) basal diet + 1 g/kg of BP from day 0 to 28; (5) basal diet + 1.5 g/kg of BP from day 0 to 28. On day 13, 15 chickens from each treatment were challenged by Salmonella Enteritidis (SE), while fifteen from each treatment were not; instead, they were kept in the same cage with the challenged chickens (exposed chickens). At 7 and 14 days post-challenge, the number of SE and coliform bacteria in the cecum and liver of colistin and BP-fed birds was lower than the control treatment. In exposed and challenged chickens, the height and surface area of villus were greater in the BP and colistin-supplemented groups. Serum concentrations of aspartate aminotransferase and alanine transaminase were greater, while serum albumin and triglycerides concentrations were lower in the control treatment. The liver of the challenged chickens had more pathological lesions than exposed birds. BP significantly decreased PPARγ gene expression in exposed chickens. In the challenged and exposed chickens, TLR4 gene expression was lower in BP and colistin-treated birds as compared to the control. In conclusion, adding BP to the diet from the day of age prevents the spread of Salmonella.

The current study was conducted to evaluate the effects of a yeast cell wall product (YCWP) on the performance, the population of Lactobacillus and coliform bacteria and PGC-1α, TLR4, IL-10 and PPARγ genes expression in the intestine of broilers. Dietary treatments were as follows: basal diet (control), control diet + 0.3 g/kg colistin or 0.15, 0.3, 0.45 and 0.6 g/kg YCWP. Feed intake and feed conversion ratio were lower in the YCWP-fed birds compared to the control. Colistin and YCWP fed birds had higher Lactobacillus and lower coliform bacteria counts than control birds (p < .05). Total and IgM antibody against sheep red blood cells was linearly increased by adding the YCWP to the diet (p < .05). Adding the YCWP to the diet linearly increased the caecal concentration of propionate (p < .05). Orthogonal and polynomial contrasts showed that the YCWP significantly improved the villus height, crypt depth, villus height: crypt depth, villus width, and villus surface area (p < .05). The lower concentrations of the YCWP (0.15 and 0.30 g/kg) increased the PPARγ transcription (p < .05), while its upper concentration (0.45 and 0.6 g/kg of diet) did not change the PPARγ gene expression. PGC-1α transcription was increased with 0.15 g/kg of the YCWP supplementation (p < .05). Dietary inclusion of the YCWP decreased the TLR4 gene expression (p < .05) and increased the downstream IL-10 cytokine (p < .05). In conclusion, YCWP improved the broiler’s performance by modifying the gut microflora. Also, YCWP supplementation had an immune regulatory effect via local and systemic responses involving TLR4, IL-10, and PPARγ.

The purpose of this study was to investigate the effects of acidifier on broilers’ performance. A total of 648-day-old broilers were assigned to four treatments (0, 1, 2, and 3 g/kg acidifier in the diet). In the grower period, the acidifier inclusion resulted in a higher average daily weight gain (ADWG) than in the control. On the 40th day of age, 3 g/kg of acidifier increased ADWG and average daily feed intake (ADFI). The highest ADWG was observed in the 3 g/kg of acidifier treatment for the whole period. Orthogonal contrast between acidifier and control indicated that cholesterol and high-density lipoprotein (HDL) concentration in the serum was lower in the acidifier-fed broilers. Inclusion of 2 and 3 g/kg of acidifier reduced Salmonella population in the ileum. Adding 2 and 3 g/kg acidifier to the diet increased crypt depth compared to other treatments. Weight and length of the tibia were also significantly increased by acidifier. The quadratic effect showed that the acidifier had a significant effect on the tibio-tarsal index. The mRNA expression of PPARγ and Toll-Like Receptor 4 (TLR4) genes in the ileum of broilers that were fed 3 g/kg acidifier was significantly higher than in other treatments. Fatty Acid-Binding Protein 1 gene showed a significant enhancement effect by the acidifier: with increasing levels of acidifier, its expression also increased. In conclusion, the acidifier improved the performance, upregulated the expression of ileal fatty acid-binding protein 1 (FABP1), TLR4, and PPARγ genes, as well as increased the tibia length, and reduced the Salmonella population in the ileum.