Response of growing chicks to supplementation of low protein diets with leucine, valine and glycine-glutamic acid

This experiment was conducted to determine the interaction effects that resulted from supplementation of low-protein diets with leucine (Leu), valine (Val), and glycine-glutamic acid (Gly-Glu) on growing broiler chicks from 11 to 24 days old. Two levels of digestible Leu (1.07 and 1.50%) and three levels of digestible Val (0.64, 0.74, and 0.84%) were investigated as a 2 × 3 factorial arrangement of treatments with 12 replicates. The diet with 1.07% digestible Leu and 0.84% digestible Val was supplemented with 0.34% Gly and 1.32% Glu as an additional treatment (T7). At 24 days old, 0.84% Val significantly improved feed conversion with 1.07% Leu, but 0.74% Val was sufficient with 1.50% Leu. The T7 diet further improved feed conversion. Increasing dietary Val from 0.64% to 0.74% significantly increased bone density and strength at the lower level of dietary Leu, while T7 significantly increased tibia breaking strength. There were significant Leu × Val interactions for villus height, crypt depth, and goblet cell numbers. Val at 0.84% maximized the development of the jejunum at the lower Leu level, while goblet cell number and crypt depth were impaired by increments of Val at the higher level of Leu. In conclusion, increasing the level of Val in low-protein grower diets significantly improved performance, bone and jejunum development of broilers, and its interaction with Leu was important. Therefore, these two amino acids (AAs) and the possibility of Gly-Glu fortification must be considered when formulating low-protein broiler diets. Keywords: bone traits, branched-chain amino acids, broilers, gut histology, performanc

Coccidiosis Vaccination and Nutrient Utilization in Broiler Chickens

Four experiments were conducted to evaluate the interrelationships among coccidiosis vaccination and nutrient utilization in floor-reared broiler chickens. Experiment 1 longitudinally compared the effects of coccidiosis vaccination and a chemical coccidiostat on broiler performance, nutrient digestibility, and intestinal morphology. Coccidiosis vaccination had no significant impact on morphology, overall body weight gain and feed intake of vaccinated birds, although vaccination impaired overall FCR. Vaccination elicited a transient reduction in digestibility of energy and nutrients, particularly for lipids, but vaccinated birds were able to recover from these reductions by 20 d. Experiment 2 assessed the impact of vaccination in digestibility of different feed ingredients and consisted of a basal diet and 3 test diets in which 30% of the basal diet was replaced with either corn, soybean meal, or distillers dried grains with solubles to allow for calculation of nutrient digestibility of individual ingredients by difference. Vaccination negatively impacted ether extract digestibility, particularly for corn. Nutrient digestibility was minimally impacted by vaccination in birds fed soybean meal, whereas ether exact digestibility was minimally impacted and nitrogen and amino acid digestibility were improved by vaccination in birds fed distillers dried grains with solubles. In experiment 3, a fat-free diet was fed to determine the impact of a coccidiosis vaccination model on ileal endogenous fatty acid flow and the values obtained were used to standardize the ether extract and fatty acid digestibility values of birds fed soybean oil or poultry fat diets. The vaccine challenge model negatively impacted digestibility of ether extract and most FA, regardless of the dietary lipid source. However, these results suggest endogenous fatty acid losses account for much of the reduction in lipid digestibility. In experiment 4, the influence of 3 starter diet energy concentrations achieved with varying soybean oil supplementation on nutrient digestibility, growth performance and processing characteristics were evaluated in coccidiosis vaccinated broilers. Vaccination reduced nutrient digestibility in all diets but did not compromise overall body weight gain, feed intake, or most processing weights. However, vaccinated birds fed higher energy density diets through greater soybean oil supplementation during the starter period had impaired feed efficiency throughout the experiment

THE EFFECTS OF EXOGENOUS ENZYME SUPPLEMENTATION ON THE PERFORMANCE, BONE QUALITY, AND NUTRIENT UTILIZATION OF BROILER CHICKENS

Two experiments were conducted to examine the effects of Allzyme® Spectrum supplementation to a reduced nutrient diet on the growth performance, energy and nutrient digestibility and utilization, bone quality, and jejunal digesta viscosity in broiler chickens. Each experiment used 300 one-day old Cobb by-product breeder chicks with 5 treatments, 10 replicates, and 6 birds per replicate cage in a randomized complete block design. The only differences between the two experiments were experiment 1 lasted for 21 days using a corn-soybean meal-based diet and experiment 2 lasted for 22 days using a wheat-soybean meal-based diet. The 5 treatments included a positive control (PC) diet that met or exceeded nutrient Ca (0.8%) and avP (0.4%) and energy (3,050 kcal/kg) requirements of birds of this age, a negative control (NC) diet that consisted of a reduction of 90 kcal/kg ME and 0.15%-point less Ca and P, and the last 3 treatments were varying inclusion levels of Allzyme® Spectrum (150, 200, 250 g/ton, respectively) added to the NC diet. Allzyme® Spectrum (Alltech, Inc., Nicholasville, KY, USA) is an enzyme complex containing xylanase and phytase. Data were analyzed using the GLM procedures of SAS (v 9.4). Simple contrasts were used to compare the PC vs. NC diet and PC vs. enzyme supplemented diets. A post-hoc test was used to generate the coefficients for the polynomial contrasts. Orthogonal polynomial contrasts were used to compare increasing levels of enzyme supplementation on the performance, jejunal digesta viscosity, nutrient digestibility and utilization, and bone mineralization of chickens. In experiment 1, increasing levels of enzyme supplementation resulted in a quadratic increase (P \u3c 0.05) in feed intake (FI), body weight gain (BWG) and feed efficiency (FE) d 9-21 and a linear increase (P \u3c 0.05) in FI d 9-21 and 0-21 and FE d 0-9, 9-21, and 0-21. In experiment 2, FI of chickens from d 9-22 and 0-22 and FE d 9-22 linearly increased (P \u3c 0.05) with increasing level of supplemental Allzyme® Spectrum. There was a quadratic effect (P \u3c 0.05) of enzyme supplementation level on BWG d 9-22 and 0-22 and FE d 9-22 and 0-22. In experiment 2, increasing levels of enzyme supplementation resulted in both a quadratic and linear decrease (P \u3c 0.001) in jejunal digesta viscosity. In both studies, increasing levels of enzyme supplementation resulted in a quadratic increase (P \u3c 0.05) in dry matter and N digestibility and retention as well as, digestible and metabolizable energy and a linear increase (P \u3c 0.05) in P and Ca digestibility. Increasing enzyme supplementation resulted in both a quadratic and linear increase (P \u3c 0.001) in P and Ca utilization in experiment 1, however it only resulted in a linear increase (P \u3c 0.001) in Ca and P utilization in experiment 2. In experiment 1, there was a quadratic increase (P \u3c 0.01) in ileal digestibility of all the amino acids with increasing level of enzyme supplementation. In experiment 2, there was a quadratic increase (P \u3c 0.05) in ileal digestibility of Arg, His, and Val and nonessential amino acids (excluding Glu: P = 0.069 and Tyr: P = 0.088) and a linear increase (P = 0.001) in ileal digestibility of Thr when comparing the enzyme supplemented diets. There was a quadratic increase (P \u3c 0.05) with increasing levels of enzyme supplementation in bone breaking strength and bone ash in both studies. In conclusion, Allzyme® Spectrum supplementation improved growth performance, energy and nutrient digestibility and utilization, and bone mineralization in broiler chickens and reduced jejunal digesta viscosity in 21- and 22-day-old broiler chickens fed wheat-based diets

CHARACTERIZATION OF PROTEIN SOURCES AND THEIR EFFECTS ON BROILER PERFORMANCE, DIGESTIVE TRACT MORPHOLOGY AND CAECAL FERMENTATION METABOLITES

The goal of this thesis was to characterize protein sources and evaluate their effects on broiler performance, digestive tract morphology and caecal fermentation. Understanding the digestion kinetics of high protein ingredients is an important step in elucidating the impact protein sources have on poultry performance and health. An in vitro assay was used to characterize the digestion kinetics of feed ingredients fed to broilers. The assay predicted the rapidly, slowly and undigested protein fraction of a variety of ingredients, and their digestion rate and extent. Compared to corn distiller dried grain with solubles, soybean meal and fish meal crude protein (CP) was digested more rapidly and to a larger extent. The rate and extent of protein digestion in feed ingredients were also evaluated using broiler chickens, and further the ileal digesta CP was characterized. Protein sources varied in rate and extent of CP and amino acid (AA) digestibility, distal ileum digesta residual AA, and total and soluble CP content. Fish meal, corn gluten meal and soybean meal had similar CP and AA extent of digestion in vivo. Among the protein sources, fish meal had the highest digestion rate for most AA. The total and soluble CP in the distal ileal content of birds fed protein sources ranged from 54 to 1466 and 6 to 347 mg, respectively. When broilers were vaccinated for coccidiosis and fed antibiotic free diets, dietary protein level (PL) and the ratio of indigestible protein (IDP) fraction affected broiler performance and meat yield. The disease status of the birds and the level of digestible AA in the diets influenced the bird’s response to dietary IDP. The level of caecal metabolites depended on dietary protein source, disease status of the birds and PL. In conclusion, data generated on in vitro and in vivo protein digestion kinetics provide an opportunity to categorize feed ingredients and use this information to establish the impact of these characteristics on broiler nutrition. Dietary PL and IDP affected broiler performance and meat yield when birds were vaccinated for coccidiosis and this was related to the characteristics of the protein sources present in the diets

Effect of Protein Source and Nutrient Density in Diets from Day Eight to Twenty One on Growth of Male Broiler Chicks

The effects of diet type, amino acid (AA), and apparent metabolizable energy (AME) levels in male broiler diets from d 8 to 21 on blood, small intestine, bone, and growth performance were investigated. Eight experimental diets with 2 protein sources [high inclusion of distiller\u27s dried grains with solubles diet (hDDGS) or high inclusion of meat and bone meal diet (hMBM)], 2 AA densities (moderate or high), and 2 AME densities (2,998kcal/kg or 3,100kcal/kg), were fed to the broiler chicks from 8 to 21 days of age (d). High AME diets may lower feed cost by lowering feed intake. Intestinal morphology changes responded to dietary treatments, which may facilitate nutrients digestion and absorption in high MBM diets as well as in high DDGS diets. In addition, high AA or AME diets from 8 to 20 d improved feed conversion during experimental phase and influenced meat yields at 55 d

Improvements to Broiler Production through Amino Acid Digestibility and Feed Additives

Improvements to broiler production can be made through the means of nutrition and preventative health care. Formulating diets based on a digestible amino acid (AA) basis decreases feed cost and improves bird performance by providing a more accurate diet based on the bird’s specific production or age nutrient requirements. The apparent ileal amino acid digestibility (AIAAD) assay utilized in Experiment 1 demonstrated inconsistent results for age effects on AIAAD of an animal by-product blends for specific AA or age. Increasing pathogenic resistance and consumer’s push on the market, has caused integrators to incorporate alternative medications or inclusion strategies to coccidiosis management. Experiment 2 demonstrated diets containing virginiamycin, with an inclusion of salinomycin during d 14-28 only, decreased lesion scores and improved performance of birds receiving an increased dose of live coccidiosis vaccine. In Experiment 3, birds fed diets utilizing an ionophore regimen and additional algal beta-glucan demonstrated improved live performance

Evaluation of Nutritional Factors that Influence the Efficacy of Tributyrin as a Feed Additive for Broilers

Tributyrin (TB) is a glyceride ester of butyrate that has the potential to improve broiler performance and intestinal development. Therefore, to fully evaluate this potential, three experiments were conducted to evaluate effect of tributyrin (TB) on broiler growth performance, nutrient digestibility, carcass characteristics, intestinal morphology, and gastrointestinal function in birds fed diets varying in composition reared in battery cages and floor pens. Experiment 1 explored the supplementation of graded doses of TB and its impact upon growth performance, nutrient digestibility, and carcass characteristics in a step-down program when added to a reduced energy and amino acid diet. A linear reduction in body weight gain and a quadratic response in feed conversion ratio was observed with increasing amounts of TB up to 5 times the recommended dose from d 0 – 35. In addition, a linear increase in fat pad yield and a linear reduction in breast meat yield were observed with increasing amounts of TB in the diet. When evaluating the 3 TB doses used in Experiment 1, growth performance was not negatively affected in birds fed 500 mg/kg of TB when compared to birds fed 3 to 5 times that level. Due to the differences between this study and previously published research, diet composition was subsequently evaluated as a potential source for differences observed in TB utilization among those studies. Therefore, in Experiment 2, TB supplementation, lipid source, lipid concentration, and corn particle size and their potential interactive effects on growth performance and nutrient digestibility were evaluated in 2 battery trials. Overall, TB efficacy was not consistently affected by dietary lipid source and lipid concentration. The same can be inferred regarding corn particle size as no differences were observed in broilers growth performance or gizzard function, with or without the inclusion of TB. Experiment 3 evaluated TB efficacy on growth performance, nutrient digestibility, and gastrointestinal pH in birds fed either animal or vegetable-based proteins reared in either battery cages or floor pens. Compared with diets containing animal protein, all vegetable-based diets with elevated soybean meal levels may result in increased non-starch polysaccharide content leading to increased short chain fatty acid (SCFA) production. Therefore, increasing SCFA production may confer a synergistic effect between an exogenous source of butyrate and increased production of endogenous butyrate. However, no effects of TB or interaction with diet type were observed in growth performance, nutrient digestibility, or ileal and cecal pH throughout the experiment in 15 d battery cage trial or a 42 d floor pen trial. However, birds fed animal protein-based diets did have improved growth performance compared to birds fed vegetable based diets. Additionally, growth performance of birds fed animal protein or vegetable protein diets with or without the inclusion of TB, was not significantly different between the two rearing environments

THE ROLE OF PROTEIN AND AMINO ACID NUTRITION IN CONTROLLING CLOSTRIDIUM PERFRINGENS IN THE GASTROINTESTINAL TRACT OF BROILER CHICKENS

A series of experiments were conducted to examine the effect of dietary protein and amino acids (AA) on intestinal Clostridium (C.) perfringens proliferation and necrotic enteritis (NE) in broiler chickens. The effects of dietary protein level and protein digestibility on the growth performance and carcass characteristics of broilers were evaluated first. Low protein (LoPro) diets supported growth performance equal to high protein (HiPro) diets when highly digestible protein supplements were incorporated. Birds fed HiPro yielded more breast meat than those fed LoPro while birds fed diets with highly digestible (HiDig) protein supplements accumulated more abdominal fat than those fed diets containing low digestible (LoDig) protein ingredients. The next experiment focused on the development of a feasible experimental model to induce NE experimentally in broilers to investigate potential dietary approaches. Different modes of challenge (oral gavage, in-feed and in-water) with different doses of C. perfringens inoculums (2 or 4 ml) were tested using microbiological, pathological and hematological parameters. The findings suggested the possibility to applly any of the evaluated treatments to induce the disease in broilers raised on litter. The next experiment was conducted to examine the effects of dietary protein level and digestibility on the growth performance and intestinal ecosystem of C. perfringens challenged and unchallenged broilers. The results of this experiment again revealed the ability of LoPro diets to maintain the growth performance of broilers as with HiPro diets, when HiDig protein supplements were included. The findings further demonstrated significant reduction in the intestinal C. perfringens numbers and severity of intestinal lesions of infected broilers when LoPro diets and HiDig protein supplements were fed. The last experiment was performed to assess the methionine requirement for optimum growth in broiler chickens fed diets supplemented with either DL-methionine (DLM) or 2-hydroxy-4-methylthiobutanoic acid (HMB) under C. perfringens infected and uninfected situations. None of the methionine sources affected the growth of C. perfringens in the broiler GIT, however, infected birds needed more dietary methionine to achieve maximum growth when DLM, but not HMB, was included in the diet. Based on the overall findings it can be concluded that the dietary approaches tested in this project may support our efforts in the development of nutritional strategies to minimize the impact of C. perfringens on broiler production in an antibiotic free livestock industry

INTERACTIVE EFFECT OF DIETARY FIBRE AND IMMUNE CHALLENGE ON THREONINE REQUIREMENT AND INTESTINAL BARRIER FUNCTION IN GROWING PIGS

High dietary fibre (DF) and immune system stimulation (ISS) are thought to limit amino acid availability for protein deposition (PD) and growth in pigs. Fibre and threonine (Thr) may also play an important role in intestinal barrier function. Therefore, this thesis evaluated the independent and combined effects of high DF and immune challenge [Salmonella typhimurium and systemic E. coli lipopolysaccharide (LPS)] on the Thr requirement for PD and growth in pigs, and on the interactive effects of DF, Thr supply and immune challenge on intestinal barrier function. A nitrogen-balance study estimated 0.68% and 0.78% standardized ileal digestible (SID) Thr required to maximize PD in pigs fed low fibre (LF) and high fibre (HF) diets, respectively when systemic ISS was not present. When systemic ISS was present, SID Thr requirement for PD was estimated at 0.76% and 0.72% for pigs fed the LF and HF diets, respectively. Therefore, HF and ISS independently, but not additively, increased the Thr requirement to maximize PD. A subsequent growth performance study using the same HF diet estimated Thr required to maximize average daily gain (ADG) at 0.76% and 0.80% SID Thr using the linear and curvilinear breakpoint model respectively. In a third study, supplementing Thr to meet the requirement for HF and systemic ISS, resulted in a numerically lower ADG in the HF-fed and Salmonella-challenged pigs, compared to the LF-fed and Salmonella-challenged pigs. This suggested that Thr supply to meet HF and ISS was not sufficient to maintain ADG during an enteric immune challenge and therefore, indicates an additive effect of HF and enteric immune challenge on Thr requirement. Finally, systemic ISS increased lactulose recovery in LF fed pigs but not in HF fed pigs, suggesting that feeding HF had a protective effect against loss of intestinal barrier integrity. This effect appears to be partly associated with mucus secretion in the gut, as HF increased fecal mucin output and ileal intestinal goblet cell numbers and tended to increase MUC2 gene expression in the ileum. The non-additive effect of systemic ISS and HF on PD is consistent with the LPS induced loss of barrier function in the LF fed pigs which contributed to increased Thr requirement for PD. Indeed, no loss of barrier function was observed when systemic ISS and HF were combined, hence no further increase in Thr requirement was observed. In contrast, we postulate that an enteric immune challenge and HF diet resulted in a higher magnitude of impact on gut mucosal protein dynamics that exceeded the gut mucosal protein response to the effect of HF alone, resulting in increased Thr utilization to support mucosal protein synthesis and thereby increasing dietary Thr requirement for growth. In summary, results indicate that immune challenge and high DF will increase Thr requirement for growth, but DF will have beneficial effects on improving intestinal barrier function in pigs

Effect of Protein Sources on Early Turkey Performance and Gastrointestinal Tract Development

Nutrition during the early life of turkey poults has a long lasting impact on bird performance, as well as gastrointestinal tract (GIT) development. This research focused on understanding the impact of protein source provided in the feed on performance and GIT development. All statistical analysis was completed using Proc Mixed in SAS 9.3 and significant differences were set at P≤0.05, while trends were identified for P≤0.10. The first study (5 x 2 factorial arrangement) evaluated apparent metabolizable energy (AMEn) and apparent ileal amino acid digestibility (AIAAD) of five high protein feed ingredients (soybean meal, SBM; corn gluten meal, CGM; canola protein concentrate, CPC; fish meal, FM; and porcine meal, PM) in male broiler chickens at 5 and 21 d with 6 replications of 30 and 8 chicks, respectively. The AMEn was not affected by bird age for CPC, FM, CGM, and SBM, however, the d 5 value for PM was higher than the d 21 value. The response of AIAAD was variable and dependent on amino acid and protein source, but overall, there was an increase in AIAAD with increasing age, with the largest increase observed for CGM. These AMEn and AIAAD values were then used to formulate the diets for a second experiment. The diets for this experiment consisted of a high SBM control diet, and four additional diets with either CPC, FM, PM, or CGM replacing 25% of the protein that was supplied by SBM in the control diet. This experiment was set up as a completely randomized design with four pens of 23 turkey poults per protein source. Body weights, feed and water intake, and mortality were recorded on a weekly basis. At the same time, four pens of 21 poults per protein source were used to study the impact of these diets on GIT development and blood metabolic profiling. At hatch, placement, d 1, 2, 3, 5, 7, 14, and 21, intestinal tract and tissue weights were collected and recorded (2 poults per replication per time point). Ileal segments were collected at hatch, placement, d 1, 3, 5, and 7 from 2 poults per replicate pen of the SBM and PM diets to study the effect of diet on intestinal morphology, number of goblet cells, and transcript abundance for selected genes relating to barrier function and inflammation. Blood samples were also drawn at these time points for blood metabolite analysis. Data were analyzed as a 5x9 factorial for tissues weights, a 2x5 factorial for histology and gene expression, and a 5x5 factorial for blood analysis. Planned contrasts were used on the performance, tissue, and blood data to compare the SBM diet to the average of the remaining diets, the PM diet to the average of the remaining diets, and the addition of animal or vegetable proteins. Inclusion of an additional protein source increased body weight up to 14 d, in comparison to poults fed the SBM diet, but feed efficiency and water consumption were not affected. The effect of diet on tissue weights were small, with the exception of the pancreas weight, which were higher in the birds fed vegetable protein diets. Age had an effect on all tissue weights, which peaked between d 2 and 7, as well as on digestive tract morphology and gene expression. There was an increase in gene expression between placement and d 1, which could illustrate the importance of feed as an activator of barrier function and the immune system. The goblet cell counts revealed a greater proportion of neutral goblet cells in PM fed birds associated with accelerated mucus maturation. The research shows there are benefits to limiting the amount of SBM provided in early turkey feeds, especially prior to two weeks of age