J T Lee

Evaluation of disinfectants commonly used by the commercial poultry industry under simulated field conditions

The correct usage of disinfectants is an important component of a successful biosecurity program. The objective of this study was to determine the effect of time, temperature, and organic matter (OM) on disinfectant efficacy. Staphylococcus aureus and Salmonella Typhimurium were used to represent gram-negative and gram-positive bacteria commonly found in commercial poultry housing. The first study evaluated the effect of temperature (4, 20, 32, or 43 degrees C) and time (1, 2, 3, 4, 6, 8, 12, 16, 20, 24, and 30 wk) on the efficacy of disinfectants diluted to working concentrations. The second study determined the effect of OM on the efficacy of working concentrations of freshly prepared disinfectants against the bacteria. For the third study, we compared the bactericidal properties of freshly prepared disinfectants and 30-wk-old disinfectants in the presence of OM. Quaternary ammonium-, chlorhexidine-, phenolic-, and binary ammonium-based solutions represented disinfectants commonly used within the poultry industry. In the first study, all of the disinfectants were effective against S. aureus and Salmonella Typhimurium regardless of treatment. However, the phenolic compound had reduced (P <or= 0.05) efficacy against Salmonella Typhimurium after 6 wk of storage at the highest temperature of 43 degrees C and after 16 wk at the second highest temperature of 32 degrees C. All of the disinfectants were effective against S. aureus regardless of temperature treatment. In the second study, the addition of sterile chicken litter had deleterious effects on all 4 classes of disinfectants against Salmonella Typhimurium. Of the disinfectants tested, the phenolic compound retained efficacy against S. aureus. In the third study, the presence of OM significantly reduced (P <or= 0.05) the efficacy of the 30-wk-old quaternary ammonium and phenolic compound against Salmonella. The fresh quaternary ammonium and binary compound achieved a greater kill (P <or= 0.05) of Staphylococcus, relative to the 30-wk-old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed before disinfection.

The effect of dietary protein level on performance characteristics of coccidiosis vaccinated and nonvaccinated broilers following mixed-species Eimeria challenge

A series of experiments were conducted to investigate the effect of starter diet protein levels on the performance of broilers vaccinated with a commercially available live oocyst coccidiosis vaccine before subsequent challenge with a mixed-species Eimeria challenge. Data indicated that an increasing protein concentration in the starter diet improved broiler performance during coccidiosis vaccination. Prechallenge performance data indicated that vaccination could decrease BW and increase feed conversion ratio. The time period most important for the observed effects appeared to be between 13 and 17 d of age. This reduction in performance parameters of vaccinated broilers compared with nonvaccinated broilers was eliminated by the conclusion of the experiments (27 d) in the diet groups with higher protein. Vaccination was effective at generating protective immunity against Eimeria challenge, as evidenced by increased (P < 0.05) BW gain, improved feed conversion, reduced postchallenge mortality, and reduced lesion development in vaccinated broilers compared with nonvaccinated broilers. These observations support numerous other reports that confirm live oocyst vaccination can be used effectively as a preventive against avian coccidiosis in commercially reared broilers. More important, these findings suggest that reduced protein concentration of starter diets can lead to significant losses in broiler performance when using a vaccination program to prevent coccidiosis.

Effect of bismuth citrate, lactose, and organic acid on necrotic enteritis in broilers

Clostridium perfringens-associated necrotic enteritis causes significant economic losses. The objective of this study was to evaluate the effect of bismuth citrate, lactose, and organic acid on the development of necrotic enteritis in broilers. The first study was a dose response that evaluated bismuth citrate at 50, 100, or 200 ppm on bacterial intestinal colonization and lesion development associated with our C. perfringens challenge model. The second study evaluated bismuth citrate, lactose, and citric acid on intestinal pH and lesion development. For the third study, we determined if lactose would enhance the efficacy of bismuth citrate against intestinal colonization and lesion development associated with C. perfringens. In study 1, intestinal lesion scores at the 50, 100, and 200 ppm bismuth citrate treatment level were reduced (P < or = 0.05) when compared with the birds fed 0 ppm bismuth citrate. Intestinal C. perfringens colonization of the 100 and 200 ppm bismuth citrate treatment group was significantly reduced when compared with birds fed 0 ppm bismuth citrate. In study 2, we found no significant differences in lesion development, after C. perfringens challenge, between birds fed 100 ppm bismuth citrate or fed a combination of 100 ppm bismuth citrate with dietary lactose or citric acid relative to the controls. The intestinal pH of birds fed 100 ppm bismuth citrate or fed a combination of 100 ppm bismuth citrate with dietary lactose or citric acid was not significantly reduced when compared with the controls. However, a significant reduction in pH was observed in birds fed a combination of 100 ppm bismuth citrate and lactose relative to the negative controls. In study 3, a decrease (P < or = 0.05) in intestinal lesion scores occurred in birds fed lactose with 100 ppm bismuth citrate, compared with the positive controls. There were no significant differences in intestinal bacterial colonization. These preliminary data suggest that bismuth citrate may reduce intestinal lesion development and C. perfringens colonization in broilers infected with necrotic enteritis.

Evaluation of increasing levels of a microbial phytase in phosphorus deficient broiler diets via live broiler performance, tibia bone ash, apparent metabolizable energy, and amino acid digestibility

&NA; The objective was to investigate increasing concentrations of an evolved microbial phytase on male broiler performance, tibia bone ash, AME, and amino acid digestibility when fed diets deficient in available phosphorus (aP). Experiment 1 evaluated the effects of phytase during a 21 d battery cage study and Experiment 2 was a 42 d grow‐out. Experiment 1 included six treatments; negative control (NC) with an aP level of 0.23% (starter) and 0.19% (grower), two positive controls (PC) consisting of an additional 0.12% and 0.22% aP (PC 1 and PC 2), and the NC supplemented with three levels of phytase (250, 500, and 2,000 U/kg). The NC diet reduced (P < 0.05) FC, BW, and bone ash. Phytase increased (P < 0.05) BW with 2,000 U/kg phytase yielding similar results to the PC2, and improved FCR and increased bone ash was observed at all phytase levels. Amino acid digestibility coefficients were increased (P < 0.05) with phytase at 250 U/kg. Phytase at all rates increased (P < 0.05) AME to levels similar level as PC diets. Linear regression analysis indicated average P equivalency values for BW and bone ash of 0.137, 0.147, and 0.226 for phytase inclusion of 250, 500, and 2000 U/kg, respectively. Experiment 2 included a PC consisting of 0.45%, 0.41%, and 0.38% aP for the starter, grower, and finisher, respectively; NC with reduced aP of 0.17%; and phytase at 500 and 2,000 U/kg. Phytase increased BW (P < 0.05) compared to the NC as 2,000 U/kg phytase resulted in further BW increases compared to the PC (starter and grower). Phytase improved FCR to levels comparable to the PC, with supplementation at 2,000 U/kg resulting in improvements beyond the PC in the starter phase. Amino acid digestibility coefficients were increased with phytase at 2,000 U/kg to levels comparable to that of the PC. These data confirm that the inclusion of phytase improves broiler performance and bone mineralization in aP reduced diets and levels beyond the traditional 500 U/kg can result in further improvements.

Changes in immune and metabolic gut response in broilers fed β-mannanase in β-mannan-containing diets

&NA; &bgr;‐galactomannans found in soy‐based broiler feed are known to cause physiological effects that are hypothesized to be related to gut inflammation. Previous studies have shown that the incorporation of &bgr;‐mannanase in the diet or as a supplement results in improvements to certain performance parameters related to gut health and feed conversion. Using kinome analysis, we characterized the mechanism of &bgr;‐galactomannan activity and supplementation with &bgr;‐mannanase on the gut of commercial broilers to understand the mode of action. Two doses of &bgr;‐mannanase (200 and 400 g/ton of feed) with and without inclusion of additional &bgr;‐galactomannan (3,000 ppm) were tested at 3 time points (d 14, d 28, and d 42 post hatch). Broilers were fed starter (d 0 to 14), grower (d 15 to 28), and finisher diets (d 29 to 42). Jejuna were collected from birds from each treatment condition and time point. Cluster analysis of the kinome data showed that birds clustered first by age, then predominantly by whether &bgr;‐mannanase had been included in the diet. Biological pathway analysis showed that the inclusion of additional &bgr;‐galactomannan into the diet resulted in increased signaling related to immune response, relative to our normal control diet (with reduced soybean meal). The addition of &bgr;‐mannanase to the enhanced &bgr;‐galactomannan diet eliminated the majority of this immune‐related signaling, indicating that the feed‐induced immune response within the jejuna had been eliminated by the addition of &bgr;‐mannanase. We also saw changes in specific metabolic and gut function pathways in birds fed &bgr;‐mannanase. These observed changes in &bgr;‐mannanase‐fed birds are likely the mechanism for the enhanced performance and feed conversion observed in birds given &bgr;‐mannanase in their diets.

Eimeria tenella oocyst shedding and output in cecal or fecal contents following experimental challenge in broilers

Two experiments were conducted to determine whether Eimeria tenella oocyst output in cecal and fecal contents, lesion development, and performance characteristics were affected by ad libitum versus restricted feeding and challenge level. In experiment 1, 144 Cobb 500 males were placed in battery cages with 6 chicks/pen. On d 20, half of the battery pens were placed on feed restriction and all broilers were orally challenged with Eimeria tenella oocysts at one of 3 challenge levels (0, 5,000, or 20,000 sporulated oocysts). Cecal and fecal material were collected separately from d 4 postchallenge through d 10 postchallenge for oocysts output (oocysts shed/g) determination. Six days postchallenge, 3 broilers from each pen were removed and subjected to necropsy for lesion assessment. In experiment 2, 96 Cobb 500 males were placed in identical battery pens with 8 chicks/pen. On d 14, restricted feeding was initiated and broilers were challenged with Eimeria tenella oocysts at one of 3 challenge levels (1,000, 5,000, or 20,000 oocysts). Twenty-four hour collections of cecal and fecal material were obtained separately from d 4 postchallenge through d 10 postchallenge for oocysts per gram and total output determination. Six days postchallenge, 4 broilers from each pen were removed and subjected to necropsy for lesion assessment. In both experiments, BW gain was not affected by challenge dose in either the ad libitum-fed or restrict-fed broilers. Increased lesion development was observed with increasing challenge levels, and oocyst shedding peaked between d 7 and 9 postchallenge in both experiments. Oocyst concentration was higher in cecal droppings compared with fecal material throughout peak shedding; however, total oocyst output for the challenge period was similar between fecal material and cecal droppings.

Efficacy of β-mannanase on broiler growth performance and energy utilization in the presence of increasing dietary galactomannan

Abstract An experiment was conducted to investigate the impact of &bgr;‐mannanase inclusion on growth performance, viscosity, and energy utilization in broilers fed diets varying in galactomannan (GM) concentrations. Treatments were arranged as a 3 (GM concentration) × 3 (&bgr;‐mannanase inclusion) factorial randomized complete block design with 12 replicates of 29 male broilers per replicate for a 42‐d experiment. Efforts were made to reduce the amount of soybean meal, and thus GM, in the basal diet with guar gum included at 0, 0.21, or 0.42% to achieve a GM supplementation of 1,500 and 3,000 ppm, respectively. Beta‐mannanase was included at 0, 200, or 400 g/ton. Broilers were fed a starter (d 0 to 14), grower (d 15 to 28), and finisher diets (d 29 to 42). Growth performance was monitored and ileal contents collected on d 14, 28, and 42 to determine ileal digestible energy (IDE) and intestinal viscosity. Increasing levels of GM negatively (P < 0.05) influenced body weight (BW) following the starter and grower periods and increased (P < 0.01) mortality corrected feed conversion ratio (FCR) throughout the study. Reduced growth performance was associated with increased (P < 0.05) intestinal viscosity and decreased (P < 0.05) IDE when GM inclusion was increased. Inclusion of &bgr;‐mannanase in diets containing supplemental GM on d 28, increased average BW to levels similar to diets without supplemental GM. Improvements in FCR were also observed with &bgr;‐mannanase inclusion in diets containing supplemental GM. Ileal digestible energy was increased (P < 0.05) with the addition of &bgr;‐mannanase on d 28 of age. Multiple interactions in growth performance, intestinal viscosity, and IDE were associated with &bgr;‐mannanase administration. In conclusion, &bgr;‐mannanase improved IDE, reduced intestinal viscosity, and improved growth performance; however, the observed benefit was dependent upon dietary GM concentration.

Impact of a multicarbohydrase containing α-galactosidase and xylanase on ileal digestible energy, crude protein digestibility, and ileal amino acid digestibility in broiler chickens

ABSTRACT Exogenous enzymatic supplementation of poultry feeds, including &agr;‐galactosidase and xylanase, has been shown to increase metabolically available energy, although little information has been published on the impact on amino acid digestibility. An experiment was conducted to investigate a multicarbohydrase containing &agr;‐galactosidase and xylanase on amino acid digestibility, ileal digestible energy (IDE), and CP in male broiler chicks. The experiment was a 2 × 2 (diet × enzyme) factorial arrangement with 15 replicates of 8 male broilers per replicate raised for 21 d in a battery setting. The 2 dietary treatments included a positive control (PC) and a negative control (NC) diet formulated to contain 2.5% less calculated AME and digestible amino acids. Each of these diets was fed with and without enzyme. Broilers were fed a starter diet from 0‐14 d (crumble) and a grower from 14‐21 d (pellet). Birds were sampled on day 21 to determine ileal amino acid digestibility, IDE, and CP digestibility. Titanium dioxide (TiO2) was used as an indigestible marker for the determination of digestibility coefficients. Total ileal amino acid digestibility was increased (P = 0.008) by 3.80% with the inclusion of enzyme. Methionine and lysine digestibility was improved (P < 0.05) with the inclusion of enzyme by 3.37% and 2.61%, respectively. Enzyme inclusion increased (P = 0.001) cysteine digestibility by 9.3%. Diet‐influenced ileal amino acid digestibility with tryptophan, threonine, isoleucine, and valine digestibility being increased (P < 0.05) in the PC when compared to the NC. IDE was decreased (P = 0.037) in broilers fed the NC diet by 100 kcal/kg feed when compared to broilers fed the PC diet. Enzyme inclusion increased (P = 0.047) IDE value by 90 kcal/kg. Crude protein digestibility was not influenced by diet; however, similar improvements in CP digestibility with enzyme inclusion were observed as with energy. These data support the benefits of a multicarbohydrase containing &agr;‐galactosidase and xylanase inclusion to improve nutrient and ileal amino acid digestibility across multiple dietary nutrient profiles.

Effects of direct-fed microorganisms and enzyme blend co-administration on intestinal bacteria in broilers fed diets with or without antibiotics

ABSTRACT Direct‐fed microorganisms (DFM) and exogenous enzymes have been demonstrated to improve growth performance in poultry and are potentially important alternatives to antibiotic growth promoters (AGP). We investigated the administration of a feed additive composed of a DFM product containing spores of 3 Bacillus amyloliquefaciens strains and an enzyme blend of endo‐xylanase, &agr;‐amylase, and serine‐protease in diets with or without sub‐therapeutic antibiotics in broiler chickens over a 42‐d growth period. Evaluation of growth performance determined feed efficiency of broiler chickens which were administered the feed additive was comparable to those fed a diet containing AGPs. Characterization of the gastrointestinal microbiota using culture‐dependent methods determined administration of the feed additive increased counts of total Lactic Acid Bacteria (LAB) relative to a negative control and reduced Clostridium perfringens to levels similar to antibiotic administration. Additionally, greater counts of total LAB were observed to be significantly associated with reduced feed conversion ratio, whereas greater counts of C. perfringens were observed to be significantly associated with increased feed conversion ratio. Our results suggest the co‐administration of DFMs and exogenous enzymes may be an important component of antibiotic free poultry production programs and LAB and C. perfringens may be important targets in the development of alternatives to AGPs in poultry production.