-The effect of a non-antibiotic growth-promoting component composed of natural phytomolecules, directfed microbials, glucomannan oligosaccharides, and organic acids on the performance, intestinal morphology and microbiology, plasma biochemistry, enzyme activities, visceral organ weights, and immune response of commercial broilers challenged with Escherichia coli was investigated. Three hundred and sixty one-day old male Ross 308 broiler chicks were randomly divided into basal diet (control, CON); control plus 0.5 mL of culture materials containing 10 8 cfu/mL of E. coli (E. coli); control with 400 mg/kg bacitracin methylene disalicylate (an antibiotic growth promoter, AGP); control plus 1000 g/t of feed of a blended mixture of natural feed additives (NAT); combination of E. coli and AGP treatments (E. coli + AGP); or the combination of E. coli and NAT treatments (E. coli + NAT). E. coli injection decreased broiler performance by lowering body weight and increasing feed intake, whereas AGP and NAT treatments improved body weight and the feed efficiency when compared to the other groups. However, feed intake was not affected by treatment. Immune response also improved with the addition of NAT, compared with control. Blood biochemistry parameters were significantly affected by the treatments. Nutrient digestibilities were increased by AGP and NAT supplementation in E. coli-challenged groups. Both AGP and NAT significantly decreased E. coli and coliform numbers in ceca. Ileal villus height was not affected by treatment, but ileal crypt depth and goblet cell counts decreased in the NAT relative to control group. Antibiotic growth promoter was somewhat more effective in improving broiler growth and health characteristics than NAT, but since NAT generally improved broiler performance compared to the control group, it can be alternatively used as an alternative to AGP in commercial broiler production.

Ascites is a major cause of mortality and morbidity in modern broiler production. Reduction of early growth, followed by compensatory gain, seems a practical and viable method to minimize losses caused by ascites. An experiment was conducted to determine if early feed restriction can reduce the incidence of ascites in broilers exposed to cool temperatures. Ross 308 cockerels (N=180) were assigned to 5 diet treatments and 2 temperature regimes, with 3 replicate pens of 6 birds per treatment and temperature. A standard grower diet was diluted by adding rice hulls at 0, 15, 30, 45, and 60% by weight from 7 to 14 d of age. On d 21 through 42, the temperature was maintained at 20 to 25°C (thermoneutral), or at 11 to 15°C (cool). Broilers exposed to cool temperatures developed higher right ventricle (RV) to total ventricle (TV) and RV to BW ratios, increased plasma triiodothyronine (T3) and thyroxine (T4) concentrations, and elevated blood values for hemoglobin concentration, mean cell volume, and hematocrit (P<0.05) but did not develop clinical ascites. Diluting the feed with rice hulls from d 7 to 14 resulted in proportional reductions in BW by d 14 (P<0.001) that tended to persist through d 28 (P=0.005), after which compensatory growth eliminated all differences in BW between diet treatment groups by d 35 (P=0.099) and d 42 (P>0.1). Exposure to cool temperatures increased key indices of ascites susceptibility, and these preascitic changes were partially prevented by diluting the feed to reduce growth performance.

Previously, we demonstrated that caffeine, a natural alkaloid, stimulates increased incidences of pulmonary hypertension syndrome (ascites) in broilers. The present study was designed to evaluate the ergogenic effects of caffeine on broiler performance and blood parameters. One-hundred-and-ninety-two Ross 308 male broiler chicks were randomly assigned at one d of age to 16 pens with 4 treatment groups. On d 3, the drinking water was supplemented with caffeine at levels of zero, 12.5, 25, and 50 mg/kg BW/day. Caffeine supplementation linearly improved (P < 0.01) body weight gain (BWG) and the feed conversion ratio (FCR); however, feed intake was not affected by caffeine (P > 0.05). On d 28, increasing caffeine supplementation caused linear reductions in plasma albumin, total protein, globulin, and triglyceride concentrations, and caffeine supplementation increased plasma uric acid concentrations (P < 0.05). On d 42, caffeine did not consistently affect plasma albumin, globulin, triglyceride, total protein, uric acid, or urea concentrations (P > 0.05), whereas plasma glucose concentrations increased linearly with increasing caffeine levels (P < 0.05). Plasma T concentrations were not affected by caffeine (P > 0.05), but plasma T concentrations were reduced by caffeine supplementation on d 28 and 42 (P < 0.05). The T:T ratios also were reduced by caffeine supplementation on d 42. Skin temperature was not influenced by caffeine supplementation (P > 0.05). There was a negative correlation between thyroid hormone concentrations and BW on d 42 (P < 0.05). It can be concluded that caffeine supplementation at the levels of 12.5 to 25 mg/kg BW/day increased BWG, decreased FCR and T, and significantly altered blood biochemistry parameters.

Crude protein (CP) levels in commercial broiler (Gallus gallus) diets, optimized for maximum yield production vs. feed cost, have only begun to be assessed for impact on immune function. In order to study immune effects of dietary CP levels, different starter phase (day 1-14) diets were fed to 230 Ross 708 male broiler chicks randomly assigned at 1 day of age into two treatment groups. Group 1: Standard diet (STD) contained 3,000 kcal AMEn/kg energy and 23.78% CP; and Group 2: Reduced crude protein diet (RCP) contained 3,000 kcal AMEn/kg energy and 21.23% CP. From day 15-35 a common standard grower/finisher diet (3,150 kcal AMEn/kg energy and 22.18% CP) was allocated to both groups. Zymosan, a glycan derived from yeast cell walls that binds to TLR 2 and Dectin-1, was used for intra-abdominal challenge. Results demonstrated that a reduced crude protein starter diet (21.23 vs. 23.78% CP) between age 1-14, while maintaining the same levels of metabolizable energy and essential amino acids, did not affect broilers growth performance or lymphoid organ weights (P > 0.05). Interestingly, basal leukocyte levels in the RCP group significantly (P < 0.01) increased in the blood compartment at d35 in the unchallenged birds. Significant enhancements to leukocyte infiltration into the abdominal cavity were also detected post-immune challenge with zymosan (day 14 and day 35; P < 0.01). Post-challenge levels of TNF-α, IL-1β, and CXCL8 gene expression cells collected from the abdominal cavity were not affected by the diets (P > 0.05). Moreover, dietary treatments did not influence percentage of ROS producing cells in the abdominal cavity (P > 0.05). To our best knowledge, this is the first study that reports the impacts of reduced crude protein diet on the innate immune response of poultry to an acute inflammation model in the abdominal cavity. Overall, our results highlight that reduced crude protein diets can be used without negatively impacting broiler performance and may enhance the capacity of broilers to recruit leukocytes upon infection.

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