Evolving enzyme technology: impact on commercial poultry nutrition

Dietary Exogenous α-Amylase Modulates the Nutrient Digestibility, Digestive Enzyme Activity, Growth-Related Gene Expression, and Diet Degradation Rate of Olive Flounder (Paralichthys olivaceus)

In this study, a 12-week feeding experiment was conducted to characterize the effects of exogenous α-amylase on the growth, feed utilization, digestibility, plasma α-amylase activity, feed degradation rate, and fecal particle size of olive flounder (Paralichthys olivaceus). Diet was supplemented with 0 (AA0; control), 100 (AA100), 200 (AA200), or 400 (AA400) mg/kg of α-amylase, respectively. Fish (273.1 ± 2.3 g) were stocked into 12 tanks (25 fish/1,000-L tank) and 3 tanks were randomly selected for each diet group. As a result, α-amylase was found to have no significant effects (p ≥ 0.05) on the growth, feed utilization parameters, and whole-body proximate compositions. α-Amylase-treated fish exhibited only a significant increase in the apparent digestibility coefficient of carbohydrates compared to the controls. In addition, in vitro analyses revealed that α-amylase dose-dependently increased (p < 0.05) the feed degradation rate, while photographs of the intestinal content after 2, 4, and 8 h of feeding demonstrated an improved degradation rate in the α-amylase-treated groups. Plasma α-amylase content was higher in the AA200 and AA400 groups, whereas the control group produced significantly larger-sized fecal particles (90% size class) than these two groups. In the intestine, no changes were observed in the expression levels of the immune-related TNF-α, IL-1β, IL-2, immunoglobulin-M, HSP-70, lysozyme, and amylase alpha-2A. However, growth-related genes IGF-1, IGF-2, TGF-β3, and growth hormone genes were upregulated in muscle tissues. Collectively, exogenous α-amylase has positive roles in the modulation of the digestibility coefficient, blood α-amylase concentration, growth-related gene expression, and diet degradation for improved digestion in olive flounder.

Carbohydrate-active enzymes in animal feed

Considering an ever-growing global population, which hit 8 billion people in the fall of 2022, it is essential to find solutions to avoid the competition between human food and animal feed for croplands. Agricultural co-products have become important components of the circular economy with their use in animal feed. Their implementation was made possible by the addition of exogenous enzymes in the diet, especially carbohydrate-active enzymes (CAZymes). In this review, we describe the diversity and versatility of microbial CAZymes targeting non-starch polysaccharides to improve the nutritional potential of diets containing cereals and protein meals. We focused our attention on cellulases, hemicellulases, pectinases which were often found to be crucial in vivo. We also highlight the performance and health benefits brought by the exogenous addition of enzymatic cocktails containing CAZymes in the diets of monogastric animals. Taking the example of the well-studied commercial cocktail Rovabio™, we discuss the evolution, constraints and future challenges faced by feed enzymes suppliers. We hope that this review will promote the use and development of enzyme solutions for industries to sustainably feed humans in the future.

Xylanase supplementation of pelleted wheat-based diets increases growth efficiency and apparent metabolizable energy and decreases viscosity of intestinal contents in broilers

This study was designed to test graded supplementation of a thermostable xylanase in pelleted, wheat-based diets fed to broiler chickens over a 28-d period. A total of 600 Ross 708 male broilers were allotted to 1 of 5 dietary treatments: positive control (PC), negative control (NC; 125 kcal of AME/kg diet reduction relative to PC), and NC supplemented with 10, 15, or 30 g/ton of xylanase. Wheat-soybean meal-based diets were pelleted and fed in 2 feeding phases (14-d each). Study outcomes included growth performance, AME, and ileal digesta viscosity with 20 battery cages of 6 birds per treatment. Data were analyzed by 1-way ANOVA along with estimation of Pearson correlation coefficients. Whereas no difference between NC and PC was observed for BW gain, NC birds exhibited increased (P < 0.05) feed intake during each feeding phase and overall, which caused improvements (P < 0.05) in feed conversion ratio (FCR) for PC vs. NC birds. The analyzed AME of PC birds was 112 kcal/kg of diet greater (P < 0.05) than for NC birds, though no differences in digesta viscosity were observed. Xylanase supplementation of the NC diet at 15 or 30 g/ton elicited overall improvements (P < 0.05) in BW gain beyond the PC, while the 30 g/ton level equalized feed intake with the PC. Regardless of level, xylanase supplementation improved (P < 0.05) the FCR relative to the NC, thereby equalizing the response with the PC. Similarly, supplementation with any xylanase level increased (P < 0.05) AME over the NC, making all treatments synonymous with the PC. Digesta viscosity of all xylanase-supplemented treatments was decreased relative to both the NC and PC treatments. Overall, this study provided clear evidence that addition of a thermostable xylanase to pelleted wheat-based diets elicited improvements in growth performance of broilers concomitant with a reduction in digesta viscosity and elevation of analyzed dietary AME content.

Responses of Combined Non-starch Polysaccharide Enzymes and Protease on Growth Performance, Meat Quality, and Nutrient Digestibility of Yellow-Feathered Broilers Fed With Diets With Different Crude Protein Levels

The aim of this study was to investigate the responses of non-starch polysaccharide (NSP) enzymes and protease combination on growth performance, meat quality, and nutrients digestibility of yellow-feathered broilers fed with corn-soybean meal basal diets with normal and subnormal crude protein (CP) levels. The experimental design was completely randomized with a 2 × 2 factorial arrangement of treatments, including six replicates of 20 birds per pen. Two basal diets were formulated with normal CP level as positive control (PC) and subnormal CP level without extra essential amino acid (AA) supplementation as negative control (NC). The basal diets were supplemented without or with NSP enzymes and protease. Broilers fed with the NC diet had lower (P < 0.05) final body weight (BW), average daily weight gain (ADG) on days 1–21, 22–56 and 1–56 and higher (P < 0.05) feed-to-gain ratio (F/G) on day 22–56 than those fed with PC diet. The broilers fed with the NC diet had higher (P < 0.05) L^* and b^* values in thigh muscle, crypt depth in the duodenum, and dry matter (DM) digestibility as well as lower (P < 0.05) villus height, musculature thicknesses, and villus height: crypt depth in the duodenum than those fed with the PC diet. Dietary NSP enzymes and protease combination increased (P < 0.05) the ADG and F/G of the broilers on days 1–56, and pH values in breast and thigh muscles as well as the digestibility of DM, gross energy (GE), CP and most AAs of the broilers on day 56. Compared with the PC diet, the combination of NSP enzymes and protease exhibited greater (P < 0.05) improvements in the digestibility of DM, CP, and some AAs (Asp, Ile, and Leu) in the broilers fed with the NC diet. In conclusion, reducing CP diet without essential AA supplementation impaired the growth performance and meat color of the thigh muscles of the broilers. The combination of NSP enzymes and protease effectively improved the growth performance, meat quality, and nutritional values of the broilers. In terms of the digestibility of DM, CP, and some AAs, the magnitude of response to the addition of NSP enzymes and protease was greater in the low nutritional-quality diet with a subnormal CP level.

Feed endoxylanase type and dose affect arabinoxylan hydrolysis and fermentation in ageing broilers

Despite the general use of endoxylanases in poultry feed to improve broiler performance, the abundance of different endoxylanase products and the variable response to their application in the field prevent a clear understanding of endoxylanase functionality in vivo. To gain insight into this functionality, we investigated the impact of endoxylanase type (Belfeed from Bacillus subtilis versus Econase XT from Nonomuraea flexuosa) and dose (10, 100, 1,000 mg/kg) in combination with broiler age on arabinoxylan (AX) hydrolysis and fermentation in broilers (Ross 308) fed a wheat-soy based diet. In a digestibility trial and a performance trial, a total of 1,057 one-day-old chicks received the control diet or 1 of the 6 endoxylanase supplemented wheat-soy based diets with, respectively, 5 replicate cages and 8 replicate pens per dietary treatment per trial. The AX content and structure, the AX digestibility values and the short-chain fatty acids produced were analysed at the level of the ileum, caeca and excreta at d 11 and 36. Endoxylanase supplementation resulted in a more extensive solubilisation of wheat AX and a reduction in the intestinal viscosity compared to the control (P < 0.05). A high endoxylanase dose was, however, required to obtain increased hydrolysis of the dietary AX along the gastrointestinal tract against the control (P < 0.001). Depending on the type of endoxylanase, a pool of AX with distinct physicochemical properties was created. The B. subtilis endoxylanase created a large pool of soluble AX in the ileum, thereby increasing ileal viscosity compared to broilers fed an endoxylanase from N. flexuosa (P < 0.001). The N. flexuosa endoxylanase mainly triggered caecal AX fermentation in young broilers, by delivering easily fermentable AX substrates with a low degree of polymerisation (P = 0.03). The effects were particularly present in young broilers (d 11). From this study, it is clear that the type and dose of endoxylanase added to wheat-soy based diets determine the nature of AX substrates formed. These, in turn, affect the intestinal viscosity and the interplay between the dietary AX compounds and microbiota, hence dictating AX digestion at young broiler ages and performance outcomes towards slaughter age.

Impact of Xylanase and Glucanase on Oligosaccharide Formation, Carbohydrate Fermentation Patterns, and Nutrient Utilization in the Gastrointestinal Tract of Broilers

This study aimed at determining how the degradation of cereal non-starch polysaccharides (NSP) by dietary enzymes during feed digestion can influence nutrient digestibility and NSP fermentability in broilers. Ninety-six one-day-old male broilers were assigned to 4 different treatments: control and enzyme-supplemented wheat-based (WC, WE) or maize-based (MC, ME) treatments. Enzyme supplementation with endo-xylanase and endo-glucanase occurred from day 20 onwards. On day 28, digesta samples were collected. Nutrient digestibility, NSP recovery, oligosaccharide profile, and short-chain fatty acids (SCFA) content were determined. Enzyme supplementation in WE resulted in a higher starch (3%; p = 0.004) and protein (5%; p = 0.002) digestion in the ileum compared to WC. Xylanase activity in WE led to in situ formations of arabinoxylan-oligosaccharides consisting of 5 to 26 pentose units in the ileum. This coincided with decreased arabinose (p = 0.059) and xylose (p = 0.036) amounts in the ceca and higher acetate (p = 0.014) and butyrate (p = 0.044) formation in WE compared to WC. Conversely, complete total tract recovery of arabinoxylan in MC and ME suggested poor maize NSP fermentability. Overall, enzyme action improved nutrient digestibility and arabinoxylan fermentability in the wheat-based diet. The lower response of the maize-based diet to enzyme treatment may be related to the recalcitrance of maize arabinoxylan as well as to the high nutritive value of maize.

Latent Anti-nutrients and Unintentional Breeding Consequences in Australian Sorghum bicolor Varieties

Modern feed quality sorghum grain has been bred to reduce anti-nutrients, most conspicuously condensed tannins, but its inclusion in the diets of monogastric animals can still result in variable performance that is only partially understood. Sorghum grain contains several negative intrinsic factors, including non-tannin phenolics and polyphenols, phytate, and kafirin protein, which may be responsible for these muted feed performances. To better understand the non-tannin phenolic and polyphenolic metabolites that may have negative effects on nutritional parameters, the chemical composition of sorghum grain polyphenol extracts from three commercial varieties (MR-Buster, Cracka, and Liberty) was determined through the use of an under-studied, alternative analytical approach involving Fourier-transform infrared (FT-IR) spectroscopy and direct ionization mass spectrometry. Supervised analyses and interrogation of the data contributing to variation resulted in the identification of a variety of metabolites, including established polyphenols, lignin-like anti-nutrients, and complex sugars, as well as high levels of fatty acids which could contribute to nutritional variation and underperformance in monogastrics. FT-IR and mass spectrometry could both discriminate among the different sorghum varieties indicating that FT-IR, rather than more sophisticated chromatographic and mass spectrometric methods, could be incorporated into quality control applications.

Sustainable Antibiotic-Free Broiler Meat Production: Current Trends, Challenges, and Possibilities in a Developing Country Perspective

Simple Summary

Chickens are raised with the assistance of the regular use of antibiotics, not only for the prevention and treatment of diseases but, also, for body growth. Overuse and misuse of antibiotics in animals are contributing to the rising threat of antibiotic resistance. Therefore, antibiotic-free broiler meat production is becoming increasingly popular worldwide to meet consumer demand. However, numerous challenges need to be overcome in producing antibiotic-free broiler meat by adopting suitable strategies regarding food safety and chicken welfare issues. This review focuses on the current scenario of antibiotic use, prospects, and challenges in sustainable antibiotic-free broiler meat production. We also discuss the needs and challenges of antibiotic alternatives and provide a future perspective on antibiotic-free broiler meat production.

Abstract

Antibiotic-free broiler meat production is becoming increasingly popular worldwide due to consumer perception that it is superior to conventional broiler meat. Globally, broiler farming impacts the income generation of low-income households, helping to alleviate poverty and secure food in the countryside and in semi-municipal societies. For decades, antibiotics have been utilized in the poultry industry to prevent and treat diseases and promote growth. This practice contributes to the development of drug-resistant bacteria in livestock, including poultry, and humans through the food chain, posing a global public health threat. Additionally, consumer demand for antibiotic-free broiler meat is increasing. However, there are many challenges that need to be overcome by adopting suitable strategies to produce antibiotic-free broiler meat with regards to food safety and chicken welfare issues. Herein, we focus on the importance and current scenario of antibiotic use, prospects, and challenges in the production of sustainable antibiotic-free broiler meat, emphasizing broiler farming in the context of Bangladesh. Moreover, we also discuss the need for and challenges of antibiotic alternatives and provide a future outlook for antibiotic-free broiler meat production.

The Current Status of the Alternative Use to Antibiotics in Poultry Production: An African Perspective

Over the years the growth and health of food-producing animals have been enhanced by the use of antibiotics. These have helped reduce on-farm mortalities, lower incidences of diseases and more importantly improve productivity. Generally, the utilization of antibiotics in feed has been reevaluated since bacterial pathogens have established and shared a variety of antibiotic resistance mechanisms that can easily be spread within microbial communities. Multiple countries have introduced bans or severe restrictions on the non-therapeutic use of antibiotics. This has therefore warranted the urgent need for alternatives. Africa is facing its own challenges as it has been reported to be one of the continents with the highest number of foodborne diseases with approximately 91 million related diseases and 137,000 death per annum. Stakeholder and policy direction has been put in place to curb this escalation; however, the problem persists. The use of alternatives has been recommended and some successfully used in other countries as well as Africa, including pro- and prebiotics and phytochemicals. This then leads to the core aim of this review which is to (1) determine the extent to which antimicrobial-resistant pathogens have affected Africa, (2) assess the current measures put in place by Africa to reduces antimicrobial resistance and finally (3) explore the alternative use of antibiotics in poultry production. Improved sanitary conditions and farm biosecurity are important alternatives that could be adopted by farmers instead of depending on antibiotic drugs for disease control and prevention.

Isolation of four xylanases capable of hydrolyzing corn fiber xylan from Paenibacillus sp. H2C

Corn fibre xylan (CX) shows high resistance to enzymatic hydrolysis due to its densely decorated side chains. To find enzymes capable of hydrolyzing CX, we isolated a bacterial strain (named H2C) from soil, by enrichment culture using non-starch polysaccharides of corn as the sole carbon source. Analysis based on the 16S rRNA sequence placed strain H2C within genus Paenibacillus. Enzymes were purified from supernatant of culture broth of strain H2C based on solubilizing activities toward CX. Four enzymes, Xyn5A, Xyn10B, Xyn11A, and Xyn30A, were successfully identified, which belong to glycoside hydrolase (GH) families, 5, 10, 11, and 30, respectively. Phylogenetic analysis classified Xyn5A in subfamily 35 of GH family 5, a subfamily of unknown function. Their activities toward beechwood xylan and/or wheat arabinoxylan indicated that these enzymes are β-1,4-xylanases. They showed high solubilizing activities toward a feed material, corn dried distiller’s grains with solubles, compared to five previously characterized xylanases.

Abbreviations : CX: corn fibre xylan; DDGS: corn dried distiller’s grains with solubles

Effects of age and supplemental xylanase in corn- and wheat-based diets on cecal volatile fatty acid concentrations of broilers1

An experiment was conducted to evaluate the effects of age and supplemental xylanase in corn- or wheat-based diets on cecal volatile fatty acid (VFA) concentrations of Ross × Ross 708 male broilers during weekly intervals from 14 to 42 d of age. Day-old chicks (1,500) were randomly distributed into 60 floor pens (25 chicks/pen; 0.078 m2/bird) and fed 1 of 4 dietary treatments (TRT) throughout the starter (1 to 14 d of age), grower (15 to 28 d of age), and finisher (29 to 42 d of age) phases with 15 replicates per TRT. Dietary TRT consisted of a 2 × 2 factorial arrangement with 2 diet types (corn- or wheat-based) and 2 xylanase inclusions (0 or 16,000 BXU/kg) as the main factors. At 14, 21, 28, 35, and 42 d of age, cecal contents were collected (4 birds/pen) for VFA analysis. Main effects of cereal grain source (P < 0.05) affected propionic, isobutyric, butyric, isovaleric, valeric, and isocaproic acid concentrations at 14, 21, 28, 35, and 42 d of age. Broilers fed corn-based diets had higher (P < 0.05) propionic, isobutyric, isovaleric, valeric, and isocaproic concentrations than those fed wheat-based diets from 14 to 42 d of age. However, broilers fed wheat-based diets had higher (P < 0.05) butyric acid concentrations at 28, 35, and 42 d of age compared with those fed corn-based diets. Individual and total VFA concentrations increased (P < 0.05) linearly from 14 to 42 d of age. Age and cereal grain interacted (P < 0.05) to affect propionic, isobutyric, butyric, isovaleric, and valeric acid concentrations. These results indicate that broiler cecal VFA concentrations are influenced by cereal grain source and age. In contrast, supplemental xylanase inconsistently influenced broiler cecal VFA concentrations. Therefore, future research evaluating factors affecting supplemental xylanase and cecal VFA production in broilers is warranted. Additionally, research investigating cereal grain source effects on cecal microflora development and fermentative patterns may be beneficial for optimizing cecal VFA production in broilers.

Energy utilization, nutrient digestibility and bone quality of broiler chickens fed Tanzania-type diets in different forms with enzymes

A study was conducted to determine the influence of feed form and microbial enzyme supplementation on energy utilization, bone quality, and amino acid and mineral digestibility of broiler chickens. Four hundred and eighty Ross 308, day-old broiler chickens were randomly assigned to eight diets formulated from commonly used ingredients in Tanzania. A 2 (pellet or mash) × 4 (control, Axtra XB, Quantum Blue (QB) and Axtra XB + QB enzyme) factorial array in a completely randomized design having six replicates per treatment (10 birds per replicate) was used. Birds were raised in climate-controlled rooms in a 3-phase; starter (0-10 days), grower (11-24 days) and finisher (25-35 days). Apparent metabolizable energy (AME), metabolizable energy intake, net energy of production, energy retained as protein (REp), and efficiency of metabolizable energy use for energy and protein retention were higher (p < 0.05) in birds fed pelleted diets. The AME and REp was higher (p < 0.05) with enzyme supplementation. Ash content, weight, length, width and breaking strength of tibia bones were highest (p < 0.05) in birds on pelleted diets. Tibia bone traits were improved (p < 0.05) when enzymes were included, particularly in a combination of QB and Axtra XB. However, potassium, magnesium, and zinc contents were highest (p < 0.05) when QB was supplemented. Digestibility of all amino acids was higher (p < 0.05) in birds supplied with pellets and with enzyme supplementation for most amino acids, except for serine. There was a positive interaction (p < 0.05) between feed form and enzymes on lysine and phenylalanine digestibility. Digestibility of Ca, P, K, S, Zn, and Fe was higher (p < 0.05) in birds fed pelleted diets, while those on mashed diets had higher (p < 0.05) digestibility of Cu and B. The digestibility of P, K, and Zn was highest (p < 0.001) when QB was added, while Ca, P, S, and B digestibility was highest when a combination of Axtra XB + QB was applied. Pelleted diets with or without enzymes improved energy utilization, digestibility of amino acids, and minerals, and increased bone strength in broiler chickens.

Effects of cereal grain source and supplemental xylanase concentrations on broiler growth performance and cecal volatile fatty acid concentrations from 1 to 40 d of age2

An experiment was conducted to evaluate the effects of feeding diets varying in cereal grain source and supplemental xylanase concentrations on growth performance and cecal volatile fatty acid (VFA) concentrations of Ross × Ross 708 male broilers from 1 to 40 d of age. A total of 1,536 day-old chicks were randomly distributed into 64 floor pens (24 chicks/pen; 0.08 m2/bird) and fed 1 of 8 dietary treatments (TRT) with 8 replicates per TRT. Experimental TRT were of either corn- (TRT 1 to 4) or wheat-based (TRT 5 to 8) origins. The 4 dietary TRT for each cereal grain source consisted of a positive control (PC) reference diet and 3 reduced AMEn diets (AMEn reduced 66 kcal/kg below PC) with supplemental xylanase at either 0 (negative control), 12,000, or 24,000 BXU/kg. Birds and feed were weighed at 1, 14, 26, and 40 d of age to determine BW gain, feed intake, and feed conversion ratio. At 26 and 40 d of age, cecal contents were collected and pooled per pen (7 birds/pen; 5 replicate pens/TRT) for VFA concentrations. No TRT differences (P > 0.05) in cumulative growth performance were observed. Likewise, no TRT differences (P > 0.05) in acetic or total VFA concentrations were observed at 26 or 40 d of age. However, cereal grain source (P < 0.05) influenced propionic, isobutyric, butyric, and isovaleric concentrations at 26 and 40 d of age with birds receiving the corn-based diets having higher (P < 0.05) cecal propionic, isobutyric, and isovaleric concentrations, and lower (P < 0.05) butyric acid concentrations than those fed the wheat-based diets. These results indicate that dietary cereal grain source may influence individual cecal VFA concentrations. However, supplemental xylanase did not affect broiler growth performance or cecal VFA concentrations. Therefore, future research evaluating factors limiting xylanase responses on broiler growth performance and cecal VFA production is warranted.

Use of Plackett-Burman design for enhanced phytase production by Williopsis saturnus NCIM 3298 for applications in animal feed and ethanol production

Distiller-dried grain solid (DDGS), a co-product of alcohol production, contains cereal grain residues, proteins, and yeast metabolites, which make it suitable in poultry feeding. However, high phytate content of DDGS limits its applicability in poultry feed. In this study, Plackett-Burman design was used to improve cell-bound phytase production by Williopsis saturnus NCIM 3298, and we achieved an enzyme activity of 269 IU/g of dry-wet biomass. The effect of this enhanced phytase-displaying yeast strain on hydrolysis of corn phytate and subsequently on ethanol production and DDGS quality was then investigated. Results of saccharification in the presence of phytase showed that reducing sugar content of liquefied mash increased by 11%, which subsequently improved the ethanol production by 18% (w/v) (p < 0.01) compared with the control. Notably, phytase treatment decreased the phytate content of corn by 70% (p < 0.01) compared with the control, thereby improving the availability of free phosphate in fermentation broth and DDGS. Thus, the results obtained suggest that the addition of W. saturnus NCIM 3298 strain has the potential of providing a new source of phytase that would be useful in the feed and ethanol industries.

The uses of microbial phytase as a feed additive in poultry nutrition – a review

Most of the phosphorus (P) in feed ingredients is present as phytate, which is poorly available for absorption in the gastrointestinal tract of different poultry species due to the lack of endogenous phytase. The supplementation of phytase increases the utilization of P by hydrolyzing phytate, which consequently may reduce the excretion of P in the environment. In addition, it has been suggested that phytase may improve the feed utilization, weight gain, egg production and egg traits, nutrient digestibility, energy availability, retention of important minerals in blood and bones. Thus, the effectiveness of phytase on performance and Ca and P absorption in layer chickens fed corn-soybean based diets has been well recognized. The current review briefly discusses the supplementation of phytase in the diet of poultry on performance and egg production and characteristics as well as amino acids and minerals availability.

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

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, α-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.

Use of antibiotics in broiler production: Global impacts and alternatives

Antibiotics are used to fight bacterial infections. However, a selective pressure gave rise to bacteria resistant to antibiotics. This leaves scientists worried about the danger to human and animal health. Some strategies can be borrowed to reduce the use of antibiotics in chicken farms. Much research has been carried out to look for natural agents with similar beneficial effects of growth promoters. The aim of these alternatives is to maintain a low mortality rate, a good level of animal yield while preserving environment and consumer health. Among these, the most popular are probiotics, prebiotics, enzymes, organic acids, immunostimulants, bacteriocins, bacteriophages, phytogenic feed additives, phytoncides, nanoparticles and essential oils.

Superior Growth Rates in Broilers Fed Wheat with Low In Vitro Feed-Xylanase Inhibition

Grain-batch variation in xylanase-inhibitor levels may account for variations in the efficacy of feed xylanase supplementation. This would make inhibition an important quality parameter in the routine analysis of feedstuffs. Two analytical procedures for testing feedstuffs against specific xylanases were researched: the high-throughput viscosity-pressure assay (ViPr) and the extraction-free remazol-brilliant-blue-beechwood-xylan (RBBX) assay. Thirty-two wheat cultivars were analyzed for inhibition of a commercial xylanase, Ronozyme WX. Four cultivars were selected for a feeding experiment in which the growth of 1440 broilers from ages 7-33 days was monitored. The treatments resulted up to 7 % difference (day 14) in broiler weight . The cultivar choice had an effect throughout the experiment ( p < 0.05). The performance ranking of the treatments corresponded better to xylanase inhibition than to crude-protein content or nonstarch-polysaccharide content. Wheat-grain xylanase-inhibitor content is therefore a highly relevant quality parameter when broiler diets are supplemented with feed xylanase.

Novel and disruptive biological strategies for resolving gut health challenges in monogastric food animal production

Use of feed antibiotics as growth promoters for control of pathogens associated with monogastric food animal morbidity and mortality has contributed to the development of antimicrobial resistance, which has now become a threat to public health on a global scale. Presently, a number of alternative feed additives have been developed and are divided into two major categories, including 1) the ones that are supposed to directly and indirectly control pathogenic bacterial proliferation; and 2) the other ones that are intended to up-regulate host gut mucosal trophic growth, whole body growth performance and active immunity. A thorough review of literature reports reveal that efficacy responses of current alternative feed additives in replacing feed antibiotics to improve performances and gut health are generally inconsistent dependent upon experimental conditions. Current alternative feed additives typically have no direct detoxification effects on endotoxin lipopolysaccharides (LPS) and this is likely the major reason that their effects are limited. It is now understood that pathogenic bacteria mediate their negative effects largely through LPS interactions with toll-like receptor 4, causing immune responses and infectious diseases. Therefore, disruptive biological strategies and a novel and new generation of feed additives need to be developed to replace feed antibiotic growth promoters and to directly and effectively detoxify the endotoxin LPS and improve gut health and performance in monogastric food animals.

Comparison of 3 phytases on energy utilization of a nutritionally marginal wheat-soybean meal broiler diet

The net energy (NE) value may be a better measure than apparent metabolizable energy (ME) of the effect of supplemental phytase on energy utilization in broilers. The present study was conducted to assess the impact of 3 microbial phytases supplemented at an unconventionally high level (1,000 FTU/kg feed) on performance and NE of broilers using the indirect calorimetric method (IC). Four treatments included: 1) Control, formulated to be deficient in ME (12.35 MJ/kg in the starter diet; 12.56 MJ/kg in the grower diet), calcium (0.72% in the starter diet; 0.60% in the grower diet), and available phosphorus (0.25% in the starter diet; 0.20% in the grower diet); 2) control + intrinsically thermostable phytase A; 3) control + intrinsically thermostable phytase B; and 4) control + coated phytase C. A completely randomized design was employed. A total of 384 male broiler chicks were used, and each treatment had 6 replicates with 16 birds per replicate. The birds were reared until d 21 in floor pens with hardwood shavings. Thirty-two birds (8 birds per treatment) were randomly selected to determine heat production and NE (from 25-28 d) following a 3-d acclimatization in the respiratory chambers. Performance results at d 21 showed that supplementation with either of the 3 phytases improved body weight (P < 0.001) and feed intake (P < 0.05), and increased the relative weights of tibia ash (P < 0.05) and toe ash (P < 0.01). Phytases A and B increased the NE value of the diet (P < 0.05). It may be concluded that the negative effects imposed by calcium and available phosphorus down-specification can be compensated by phytase supplementation in general, and intrinsically thermostable phytases improve the ME and NE value. However, phytase did not reduce heat production, heat increment, or increase NE:ME in birds.

Fermentation and addition of enzymes to a diet based on high-moisture corn, rapeseed cake, and peas improve digestibility of nonstarch polysaccharides, crude protein, and phosphorus in pigs

Fluctuating prices of cereals have led to an interest in alternative ingredients for feed. The aim of this study was to evaluate the effect of fermentation and the addition of nonstarch polysaccharide (NSP)-degrading enzymes on the ileal and total tract digestibility of nutrients of a diet based on locally grown crops. Four diets were fed including a nonfermented liquid standard grower diet (Control) and 3 experimental diets based on high-moisture corn, rapeseed cake, and peas fed as nonfermented liquid feed (nFLF), fermented liquid feed (FLF), or FLF supplemented with an enzyme mixture of β-glucanase + xylanase + pectinase (FLF+Enz). The FLF was prepared by mixing feed and water (1:2.5, wt/wt) and, once daily, replacing 50% of the mixture with an equal amount of fresh feed and water. The diets were fed to 8 ileal cannulated barrows in a double Latin square design. Ileal digesta and feces were collected after an adaption period of 10 d. Results showed microbiologically good-quality fermented diets. The levels of Enterobacteriaceae were 5.1 to 5.4 log cfu/g in FLF and FLF+Enz vs. 6.3 log cfu/g in nFLF in the ileum and 5.1 to 5.2 log cfu/g in FLF and FLF+Enz vs. 6.3 log cfu/g in nFLF in the feces. Apparent total tract digestibility (ATTD) of CP was increased by fermentation (73.2% in FLF vs. 69.0% in nFLF; P = 0.033), and digestibility of P showed a tendency (P = 0.073) toward an increase. Addition of the enzyme mixture resulted in a pronounced reduction of dietary NSP compared with FLF (12.8% total NSP in FLF+Enz vs. 15.9% total NSP in FLF; P< 0.001), which also led to increased apparent ileal digestibility (AID) of total and insoluble NSP (total NSP, 31.1% in FLF+Enz vs. 13.6% in FLF; P = 0.002). The Control did not, in general, show higher digestibility values than the experimental diet. However, in the cases were it did, fermentation and enzyme addition brought the digestibility to the level of the Control. In conclusion, fermentation increased the ATTD of CP and the AID of P, with the same tendency (P ≤ 0.07) for the ATTD. Addition of NSP-degrading enzymes resulted in a pronounced reduction in the concentration of NSP in the feed along with increased AID of NSP. Hence, the experimental diet seems to be a possible alternative to a traditional diet for pigs.

Evaluation of phytate-degrading Lactobacillus culture administration to broiler chickens

Probiotics have been demonstrated to promote growth, stimulate immune responses, and improve food safety of poultry. While widely used, their effectiveness is mixed, and the mechanisms through which they contribute to poultry production are not well understood. Microbial phytases are increasingly supplemented in feed to improve digestibility and reduce antinutritive effects of phytate. The microbial origin of these exogenous enzymes suggests a potentially important mechanism of probiotic functionality. We investigated phytate degradation as a novel probiotic mechanism using recombinant Lactobacillus cultures expressing Bacillus subtilis phytase. B. subtilis phyA was codon optimized for expression in Lactobacillus and cloned into the expression vector pTRK882. The resulting plasmid, pTD003, was transformed into Lactobacillus acidophilus, Lactobacillus gallinarum, and Lactobacillus gasseri. SDS-PAGE revealed a protein in the culture supernatants of Lactobacillus pTD003 transformants with a molecular weight similar to that of the B. subtilis phytase. Expression of B. subtilis phytase increased phytate degradation of L. acidophilus, L. gasseri, and L. gallinarum approximately 4-, 10-, and 18-fold over the background activity of empty-vector transformants, respectively. Phytase-expressing L. gallinarum and L. gasseri were administered to broiler chicks fed a phosphorus-deficient diet. Phytase-expressing L. gasseri improved weight gain of broiler chickens to a level comparable to that for chickens fed a control diet adequate in phosphorus, demonstrating proof of principle that administration of phytate-degrading probiotic cultures can improve performance of livestock animals. This will inform future studies investigating whether probiotic cultures are able to provide both the performance benefits of feed enzymes and the animal health and food safety benefits traditionally associated with probiotics.

Characterization of bacteriophages virulent for Clostridium perfringens and identification of phage lytic enzymes as alternatives to antibiotics for potential control of the bacterium

There has been a resurgent interest in the use of bacteriophages or their gene products to control bacterial pathogens as alternatives to currently used antibiotics. Clostridium perfringens is a gram-positive, spore-forming anaerobic bacterium that plays a significant role in human foodborne disease as well as non-foodborne human, animal, and avian diseases. Countries that have complied with the ban on antimicrobial growth promoters in feeds have reported increased incidences of C. perfringens-associated diseases in poultry. To address these issues, new antimicrobial agents, putative lysins encoded by the genomes of bacteriophages, are being identified in our laboratory. Poultry intestinal material, soil, sewage, and poultry processing drainage water were screened for virulent bacteriophages that could lyse C. perfringens and produce clear plaques in spot assays. Bacteriophages were isolated that had long noncontractile tails, members of the family Siphoviridae, and with short noncontractile tails, members of the family Podoviridae. Several bacteriophage genes were identified that encoded N-acetylmuramoyl-l-alanine amidases, lysozyme-endopeptidases, and a zinc carboxypeptidase domain that has not been previously reported in viral genomes. Putative phage lysin genes (ply) were cloned and expressed in Escherichia coli. The recombinant lysins were amidases capable of lysing both parental phage host strains of C. perfringens as well as other strains of the bacterium in spot and turbidity reduction assays, but did not lyse any clostridia beyond the species. Consequently, bacteriophage gene products could eventually be used to target bacterial pathogens, such as C. perfringens via a species-specific strategy, to control animal and human diseases without having deleterious effects on beneficial probiotic bacteria.

Effect of phytic acid and microbial phytase on the flow and amino acid composition of endogenous protein at the terminal ileum of growing broiler chickens

The effects of phytic acid and microbial phytase on the flow and composition of endogenous protein at the terminal ileum of broiler chickens were investigated using the peptide alimentation method. Phytic acid (fed as the sodium salt) was included in a synthetic diet at 8.5, 11.5 and 14.5 g/kg (or 2.4, 3.2 and 4.0 g/kg phytate-phosphorus) and each diet was fed without or with an Escherichia coli-derived microbial phytase at 500 phytase units/kg diet. A control containing no phytate was fed as a comparison to estimate basal endogenous flows. Ingestion of phytic acid increased (P < 0.05) the flow of endogenous amino acids and N by an average of 47 % at the lowest phytic acid concentration and 87 % at the highest. The addition of microbial phytase reduced (P < 0.05) the inimical effects of phytic acid on endogenous amino acid flow at all dietary phytic acid levels. The composition of endogenous protein was also influenced (P < 0.10-0.001) by increasing phytic acid concentrations and phytase addition. The effects of phytic acid and phytase on endogenous flow and composition of endogenous protein, however, varied depending on the amino acid. It is concluded that the effects of phytase on amino acid digestibility may be mediated, in part, through a route of reduced endogenous loss.