Progress in ileal endogenous amino acid flow research in poultry

The progress in our understanding of the endogenous protein concept over the past century is reviewed.Nondietary proteins found in the digesta at the terminal ileum of poultry,known as endogenous protein loss,are comprised of digestive secretions,mucus and sloughed gut epithelial cells.The measurement of this loss is of fundamental importance because it is an indicator of gut metabolism and is essential to adjust apparent estimates of ileal amino acid digestibility.The ileal endogenous amino acid losses comprise of two components,namely basal and specific losses.The basal losses are fixed and associated with feed dry matter intake,whereas the specific losses are variable and induced by the presence of dietary components such as fibre and anti-nutrients.Currently there is no methodology available to directly measure the specific endogenous losses and these losses are calculated by determining the basal and total(basal plus specific)losses and,then subtracting the basal losses from total losses.The seminal features,specific applications and shortcomings of available methodologies are briefly outlined as well as the practical challenges faced in using the published endogenous amino acid loss values for true digestibility corrections.The relevance of taurine as a component of endogenous protein flow in poultry is identified for the first time.

Encapsulated peracetic acid as a valid broad‑spectrum antimicrobial alternative,leading to beneficial microbiota compositional changes and enhanced performance in broiler chickens

Background Antimicrobial alternatives are urgently needed,including for poultry production systems.In this study,we tested the potential broad-range antimicrobial alternative peracetic acid,delivered in feed via the hydrolysis of encapsulated precursors through a 28-day study using 375 Ross 308 broiler chickens.We tested two peracetic acid concentrations,30 and 80 mg/kg on birds housed on re-used litter,and we evaluated the impact of both levels on gut microbial communities,bacterial concentration,antimicrobial resistance genes relative abundance and growth performance when compared to control birds housed on either clean or re-used litter.Results Body weight gain and feed conversion ratio improved in peracetic acid fed birds.At d 28,birds given 30 mg/kg of peracetic acid had a decreased Firmicutes and an increased Proteobacteria abundance in the jejunum,accompanied by an increase in Bacillus,Flavonifractor and Rombustia in the caeca,and a decreased abundance of tetracycline resistance genes.Chicken given 80 mg/kg of peracetic acid had greater caecal abundance of macrolides lincosamides and streptogramins resistance genes.Growth performance on clean litter was reduced compared to reused litter,which concurred with increased caecal abundance of Blautia,decreased caecal abundance of Escherichia/Shigella,Anaerostipes and Jeotgalicoccus,and greater gene abundance of vancomycin,tetracycline,and macrolides resistance genes.Conclusions Peracetic acid could be used as a safe broad-spectrum antimicrobial alternative in broilers.Encapsulated precursors were able to reduce the bacterial concentration in the jejunum whilst promoting the proliferation of probiotic genera in the caeca,especially at the low peracetic acid concentrations tested,and improve growth performance.Moreover,our findings offer further insights on potential benefits of rearing birds on re-used litter,suggesting that the latter could be associated with better performance and reduced antimicrobial resistance risk compared to clean litter rearing.

Trends in feed evaluation for poultry with emphasis on in vitro techniques

Accurate knowledge of the actual nutritional value of individual feed ingredients and complete diets is critical for efficient and sustainable animal production.For this reason,feed evaluation has always been in the forefront of nutritional research.Feed evaluation for poultry involves several approaches that include chemical analysis,table values,prediction equations,near-infrared reflectance spectroscopy,in vivo data and in vitro digestion techniques.Among these,the use of animals(in vivo)is the most valuable to gain information on nutrient utilization and is more predictive of bird performance.However,in vivo methods are expensive,laborious and time-consuming.It is therefore important to establish in vitro methods that are reliable,rapid and practical to assess the nutritional quality of feed ingredients or complete diets.Accuracy of the technique is crucial,as poor prediction will have a negative impact on bird performance and,increase feed cost and environmental issues.In this review,the relevance and importance of feed evaluation in poultry nutrition will be highlighted and the various approaches to evaluate the feed value of feed ingredients or complete diets will be discussed.Trends in and practical limitations encountered in feed evaluation science,with emphasis on in vitro digestion techniques,will be discussed.

Evaluation of the effect of different wheats and xylanase supplementation on performance,nutrient and energy utilisation in broiler chicks

The aim of this study was to evaluate the performance, nutrient utilisation and energy metabolism of broiler chicks fed 8 different wheat samples, supplemented or not with xylanase. Seven-hundred sixty eight male broilers(1-day-old) were distributed to 16 experimental treatments(6 replicates per treatment). The treatments were in a factorial arrangement with 8 different wheats and 2 levels of xylanase(0 or 16,000 BXU/kg). The predicted apparent metabolisable energy(AME) of the wheat samples ranged from 13.0 to 13.9 MJ/kg and all diets were formulated to contain the same amount of wheat. Body weight gain(BWG) and feed intake(FI) were measured at 21 d, as was jejunal digesta viscosity, and feed conversion ratio(FCR) calculated. On day 24, one representative bird per pen was selected to calculate whole body energetics. At 21 d, 3 chicks per replicate were randomly allocated to metabolism cages for energy and nutrient utilisation determinations, and were continued on the experimental diets until 24-d-old. No interactions were observed for any performance response variables, ileal nutrient utilisation or digesta viscosity. Xylanase improved BWG and reduced FCR and digesta viscosity(P < 0.05). Wheat influenced dry matter(DM) utilisation and xylanase increased ileal digestible energy(P = 0.04). Xylanase also improved(P < 0.05) DM and nitrogen retention. Apparent metabolisable energy and AME corrected for nitrogen(AMEn) were subject to an interaction whereby wheats 2 and 6, which returned the lowest AME and AMEn values, responded to xylanase supplementation and the remainder did not. Net energy for production and the efficiency of energy use for production were not influenced by xylanase, but were affected by wheat(P < 0.05). Despite the significant differences between wheats with regards to their nutrient utilisation and energy metabolism in birds, xylanase removed this variance and resulted in more homogeneous performance.

Influence of barley inclusion method and protease supplementation on growth performance,nutrient utilisation,and gastrointestinal tract development in broiler starters

The influence of the method of barley inclusion(fine,coarse and whole barley)in a wheat-based diet and protease supplementation(0 and 0.20 g/kg)on growth performance,nutrient utilisation and gastrointestinal tract development of broilers(d 1 to 21)was evaluated in a 32 factorial arrangement.Whole barley(WB)grains were ground in a hammer mill to pass through the screen sizes of 2.5 and 8.0 mm to achieve fine(FB)and coarse(CB)barley particle sizes,respectively.A total of 288,one-day-old male broilers were allotted to 36 cages(6 cages/treatment;8 birds/cage).There was no significant(P>0.05)interaction between barley inclusion method and protease for any growth performance or nutrient utilisation parameters.Birds fed diets containing CB and WB showed higher(P<0.05)weight gain,and digestibility of dry matter,nitrogen,calcium,gross energy,and ileal digestible energy compared to those fed FB diets.Compared to the birds fed FB diets,feed per gain was lower(P<0.05)in birds fed diets made of WB.Fat digestibility of the birds fed CB was higher(P<0.05)than those fed FB and WB birds.Compared to FB and CB diets,inclusion of WB resulted in heavier(P<0.05)gizzards but reduced(P<0.05)gizzard pH.Supplemental protease,however,had no effects(P>0.05)on growth performance and nutrient utilisation,most likely due to the well balanced digestible amino acids and high inherent digestibility of protein in the basal diet,and/or the presence of exogenous carbohydrase and phytase.In conclusion,the present results showed that the inclusion of coarsely ground and whole barley in a wheat-based diet can enhance nutrient and energy utilisation and is beneficial to the growth performance of young broilers.