Comparative efficacy of a yeast product and bacitracin methylene disalicylate in enhancing early growth and intestinal maturation in broiler chicks from breeder hens of different ages.

The intestine of the newly hatched chick is immature at hatch. Yeast contains nucleotides and ß-glucans that enhance intestinal development and chick growth. Accordingly, a 14-d experiment was conducted to evaluate the efficacy of a novel yeast product and bacitracin methylene disalicylate in enhancing early growth and intestinal maturation in chicks obtained from young (26-27 wk old) and old (58 to 59 wk old) breeder hens. Chicks (384) were randomly assigned to 8 dietary treatments. Treatment 1 (YH) consisted of chicks, from young hens, fed corn-soybean meal (SBM) diet alone. Treatment 2 (YHB) consisted of chicks, from young hens, fed corn-SBM basal into which BMD was added at 0.055 g/kg. Treatment 3 (YHE) consisted of chicks, from young hens, fed corn-SBM basal into which yeast extract (YE) was added at 0.075% level. Treatment 4 (YHED) consisted of chicks, from young hens, fed corn-SBM basal into which YE was added at 0.15% level. Treatments 5 (OH), 6 (OHB), 7 (OHE), and 8 (OHED) consisted of chicks from old hens fed diets similar to those given to YH in treatments 1, 2, 3, and 4, respectively. Growth performance (body weight gain and feed conversion ratio) was evaluated on d 7 and 14. Intestinal tissue samples were also analyzed for alkaline phosphatase (ALP) activity as an indicator of intestinal maturation on d 4 and 13 of experiment. Results showed that by d 14 of experiment, only BMD treatments (YHB and OHB) improved body weight gain (P < 0.05). However, the body weight gains of chicks in the yeast-supplemented treatments (YHE, YHED, OHE, and OHED) were statistically similar (P > 0.05) to those of the BMD treatments. Ileal ALP activity was consistently enhanced by BMD and yeast product supplemented at 0.075% of the diet. It was concluded that antibiotic BMD and our novel yeast product supplemented at 0.075% of the diet improved early chick growth and maturation of the ileal segment of the small intestine.

Influence of Salmonella enterica serovar Typhimurium infection on intestinal goblet cells and villous morphology in broiler chicks.

Live broiler chickens are important in the transmission of Salmonella to humans. Reducing Salmonella levels in the intestine of broiler chickens, in part, requires understanding of the interactions between Salmonella and the intestinal barriers that represent the first line of defense. Such barriers include the mucus layer (composed of mucins secreted by goblet cells) and the underlying epithelium. Two experiments were conducted to evaluate the effect of Salmonella Typhimurium infection on intestinal goblet cell dynamics (density and size) and villous morphology in broiler chicks. In Experiment 1, broiler chicks were either challenged with sterile media (control treatment) or orally given 7.4 x 10(7) colony-forming units (CFU) at 3 days of age (termed the CST treatment). Treatments were similar in Experiment 2, except that chicks in the CST treatment were challenged with 7.8 x 10(6) CFU at 4 days of age. Duration of each experiment was 14 days. At 7 days postchallenge (PC) in Experiment 1, jejunal tissue sections were collected, formalin-fixed, and routinely processed for histologic measurement of villous morphometric indices. In Experiment 2, at 10 days PC, jejunal tissue sections were collected and processed for histologic determination of goblet cell numbers and size, in addition to villous measurements. Results showed that Salmonella Typhimurium infection increased goblet cell density, reduced villous surface area, increased the incidence of epithelial exfoliation, and increased the incidence of heterophil influx into the lamina propria (P < 0.05). It was concluded that Salmonella Typhimurium infection impacts goblet cell biology and exerts morphopathologic changes in the jejunum of broiler chicks.

Effect of dietary glutamine supplementation on Salmonella colonization in the ceca of young broiler chicks.

Live poultry is an important vehicle for transmitting Salmonella Typhimurium to humans that have salmonellosis. It is therefore imperative to reduce Salmonella Typhimurium levels in the gastrointestinal tract of live chickens. Glutamine is an established immunonutrient that is capable of alleviating disease conditions in humans and rats. Thus, 2 experiments that used Ross broiler chicks were conducted to evaluate the effect of glutamine supplementation at 1% level of the diet on cecal Salmonella Typhimurium levels in young broiler chicks. Experiment 1 consisted of i) treatment 1 (control, CN), in which chicks were given an unmedicated corn-soybean meal basal starter diet without glutamine supplementation or Salmonella Typhimurium challenge; ii) treatment 2 (CST), in which chicks were given the same diet as CN but challenged with 3.6 x 10(6) cfu Salmonella Typhimurium/mL at 3 d of age; and iii) treatment 3 (GST), in which chicks were given the unmedicated corn-soybean meal basal starter diet supplemented with glutamine at 1% level, and challenged with 3.6 x 10(6) cfu at 3 d of age. Experiment 2 used similar treatments (CN, CST, and GST), except that chicks in CST and GST were challenged with 7.4 x 10(7) cfu Salmonella Typhimurium/mL, and a fourth treatment was added. The fourth treatment consisted of chicks that were not challenged with Salmonella Typhimurium but given the same diet as in GST. Duration of each experiment was 14 d. Growth performance of chicks was monitored weekly, and cecal Salmonella Typhimurium concentration was microbiologically enumerated on d 4, 10, or 11 postchallenge. Results showed that glutamine supplementation improved BW and BW gain in experiment 2 (P < 0.05) but did not reduce cecal Salmonella Typhimurium levels in either experiment (P > 0.05). The optimum supplemental level of glutamine that will enhance intestinal resistance to Salmonella Typhimurium colonization should be determined.

Evaluation of the efficacy of yeast extract in reducing intestinal Clostridium perfringens levels in broiler chickens.

The etiological agent of necrotic enteritis is Clostridium perfringens. Traditionally, necrotic enteritis is controlled with in-feed antibiotics. However, increasing consumer demand for drug-free poultry has fostered the search for nonantibiotic alternatives. Yeast extract contain nucleotides that are immunomodulatory and also essential for cellular functions. An experiment was conducted to evaluate the efficacy of NuPro yeast extract (Alltech Inc., Nicholasville, KY) in reducing intestinal C. perfringens levels in broiler chickens. One hundred ninety-two 1-d-old male broiler chicks were obtained and randomly assigned to 6 treatments in a battery cage trial. Treatment 1 consisted of chicks fed a corn-soybean meal basal diet (BD) without added bacitracin methylene disalicylate or NuPro. Treatment 2 consisted of chicks fed BD into which bacitracin methylene disalicylate was added at 0.055 g/kg. Treatment 3 consisted of chicks fed BD supplemented with NuPro at a 2% level for the first 10 d of the experiment. Treatments 4 (PX), 5, and 6 (PN) consisted of chicks that were challenged with 3 mL of the C. perfringens inoculum (~10(7) cfu/mL) on d 14, 15, and 16 of the experiment and fed diets similar to treatments 1, 2, and 3, respectively. On d 1 and 7 postchallenge, intestinal C. perfringens levels, lesion scores, and alkaline phosphatase activity were assessed. On d 1 postchallenge, C. perfringens level in treatment 5 (2.09 log(10) cfu/g) was lower (P < 0.05) compared with the PX treatment (4.71 log(10) cfu/g) but similar to the PN treatment (2.98 log(10) cfu/g). A similar trend was observed on d 7 postchallenge. NuPro supplementation enhanced alkaline phosphatase activity (P < 0.05) in C. perfringens-challenged chicks and appeared to reduce intestinal lesion scores. Although dietary supplementation of NuPro in the PN treatment reduced C. perfringens levels by 1.73 and 0.68 log(10) cfu/g compared with the PX treatment on d 1 and 7 postchallenge, respectively, these reductions were not significant. Extending the period of NuPro supplementation beyond the first 10 d of life should be considered for achieving significant reduction in intestinal C. perfringensg levels.

Intestinal cytokine response of commercial source broiler chicks to Salmonella typhimurium infection.

Development of molecular-based immunotherapeutic strategies for controlling Salmonella Typhimurium (ST) infection in poultry requires a better understanding of intestinal and cecal cytokine responses. Accordingly, an experiment was conducted to measure changes in intestinal cytokine expression when commercial source broiler chickens were challenged with a nalidixic acid-resistant ST. Ross broiler chicks were nonchallenged with ST (control treatment) or challenged by orally giving 7.8 x 10(6) cfu at 4 d of age (STC treatment). Each treatment consisted of 4 replicate pens with 14 chicks per pen. Expression levels of proinflammatory cytokines, interferon-gamma, and antiinflammatory interleukin (IL)-10 were determined at 5 and 10 d postchallenge (PC). Intestinal flushes were also collected from each treatment at 7 d PC to estimate IgA and IgG. Results showed an upregulation in IL-1beta mRNA in STC chicks at 5 d PC. By 10 d PC, the expression of IL-1beta was further increased and accompanied by an upregulation of IL-6 and interferon-gamma mRNA, whereas IL-10 mRNA expression decreased. It was concluded that ST induced an intestinal mucosal inflammatory response in commercial source broiler chicks less than 2 wk of age.

Response of turkey poults to soybean lectin levels typically encountered in commercial diets. 2. Effect on intestinal development and lymphoid organs.

Lectins are capable of altering intestinal morphology by binding to and disrupting the intestinal brush border membrane. They are also known to alter the weight of lymphoid organs. Therefore, we evaluated the effect of soybean lectin (SBL) on intestinal morphology and lymphoid organ weights of poults fed diets containing SBL. Dietary treatments evaluated in this study included a cornstarch and casein-based control (lectin-free) semipurified diet (PD) and semipurified diets containing 0.024 or 0.048% SBL (PDL and PDH, respectively). Experimental diets were fed from hatch to 14 d. Morphological evaluation of the intestine involved measurement of the villi height and perimeter, crypt depth, villus:crypt, and thickness of the muscle layer in the jejunum. Intestinal physical characteristics were also determined by measuring intestinal weight, length, and volume. Results indicated that 0.048% SBL in PDH increased villus:crypt and reduced total intestinal length in turkey poults. In addition, both the 0.024 and 0.048% dietary SBL levels reduced thymus weights. It was concluded that dietary SBL up to 0.048% enhanced intestinal development by increasing villus:crypt, but might alter the structural integrity of lymphoid organs.

Investigating the possibility of monitoring lectin levels in commercial soybean meals intended for poultry feeding using steam-heated soybean meal as a model.

Native soybean lectins (SBL) could potentially have deleterious effects on young animals. The objectives of this study were to determine the optimum processing temperature and time at which SBL is inactivated and to investigate the possibility of using urease activity (UA) to predict residual lectin levels in soybean meal (SBM). Raw defatted SBM was steam-heated at incremental temperatures between 90 and 120 degrees C for 5 to 20 min in an autoclave. The processed meals were subjected to native-PAGE and measurement of total carbohydrate-binding lectin (TCBL), agglutinating lectin (AL), UA, and trypsin inhibitor (TI). Processing severity was evaluated by determining protein solubility in 0.2% potassium hydroxide. Results indicated that levels of all antinutrients (TCBL, AL, UA, and TI) decreased with increasing processing temperature (P < 0.05). The intensity of the lectin band on the electrophoresis gel was considerably reduced when meal was heated at 100 degrees C for 5 min. This result implied that lectin inactivation occurred at 100 degrees C. More than 90% of all the original antinutrient levels in the raw meal were destroyed when meals were heated at 100 degrees C for 5 min. Meals processed at 100 degrees C for 5 to 20 min had protein solubility values (80 to 85%) indicative of adequate processing. The denaturation pattern of UA was highly correlated with that of SBL (r > or = 0.73), indicating that UA could be used for monitoring lectin levels in commercial meals. We concluded that UA of 0.03 to 0.09 units of pH change are indicative of adequately processed meals that contain negligible lectin levels.

Response of turkey poults to soybean lectin levels typically encountered in commercial diets. 1. Effect on growth and nutrient digestibility.

Lectins are known to bind to the intestinal brush border membrane and induce antinutritional effects such as disruption of the brush border membrane (BBM) and reduced nutrient digestibility in laboratory rodents. Because soybean lectin (SBL) is usually present in poult starter diets, 2 similar experiments with starting turkey poults were conducted to investigate the effects of purified SBL on growth performance and nutrient digestibility. Experimental diets were a corn starch-casein based control (lectin-free) semipurified diet (PD), semipurified diets containing 0.024 or 0.048% soybean lectin (PDL, PDH), and a corn-soybean meal diet (SBD). Experimental diets were fed from hatch to 14 d. Antibodies specific for soybean lectin were detected in the serum of poults fed the PDL and PDH diets, implying that the SBL in these diets remained active in the digestive tract. Poults fed the control PD or SBD grew equally well. The 0.024% SBL level in PDL had no significant detrimental effect on any parameters assessed in the 2 experiments. In contrast, the 0.048% SBL level in the PDH gave inconsistent results for feed efficiency (FE) and brush border enzyme levels. For instance, on d 6 in experiment 2, poults fed the PDH had poorer FE (P < 0.05) compared with the control PD treatment, but had similar FE to poults fed the PD in experiment 1. In conclusion, SBL present at levels up to 0.024% of the diet would not cause antinutritional effect in turkey poults up to 2 wk of age.