Organic Acids Placed into the Cloaca to Reduce Campylobacter Contamination of Broiler Skin During Defeathering

Campylobacter numbers on broiler carcasses can increase dramatically during defeathering because of leakage of contaminated gut contents in the feather-picking machine. Food-grade organic acids have been shown to be effective in killing bacteria. Placement of organic acids into the cloaca prior to defeathering was tested to determine if such a treatment could lower the number of Campylobacter that escape and contaminate broiler breast skin during automated feather removal. Campylobacter numbers on the breast skin of treated carcasses increased during defeathering but resulted in numbers that were only about 2% of those observed on control carcasses. Placement of food-grade organic acids in the cloaca of broiler carcasses may be useful as a means to lessen the impact of automated defeathering on the microbiological quality of carcasses during processing.     

High virus titer in feather pulp of chickens infected with subgroup J avian leukosis virus

Subgroup J avian leukosis viruses (ALVs), which are a recombinant virus between exogenous and endogenous ALVs, can spread by either vertical or horizontal transmission. Exogenous and endogenous ALVs can be detected in feather pulp. In this study, virus titers in feather pulp of chickens infected with subgroup J ALV were compared with those of plasma and cloacal swab. All of the broiler chickens inoculated with subgroup J ALV at 1 day old were positive for virus from feather pulp during the experimental period of between 2 wk and 8 wk of age. Virus titers in feather pulp of some broiler chickens infected with subgroup J ALV were very high, ranging from 10(7) to 10(8) infective units per 0.2 ml. Virus titers in feather pulp were usually the highest among the samples of plasma, cloacal swab, and feather pulp tested. In another experiment in which layer chickens were inoculated with subgroup J ALV at 1 day old, virus was detected in feather pulp from 2 wk until 18 wk of age, and virus persisted longer in feather pulp than in plasma. Almost all of the layer chickens tested were positive for virus by polymerase chain reaction (PCR) with DNA extracted from feather pulp samples at 2, 4, and 10 wk of age, and the PCR from feather pulp was more sensitive than virus isolation from plasma, cloacal swab, and feather pulp. All above results indicate that samples of feather pulp can be useful for virus isolation and PCR to confirm subgroup J ALV infection.     

Detection of subgroup J avian leukosis virus infection in Australian meat-type chickens

OBJECTIVE: To determine the extent of avian leukosis virus subgroup J (ALV-J) infection in Australian broiler breeder flocks, using virus isolation and molecular biological detection. Any resultant ALV-J viral isolates to be characterised by neutralisation cross testing in order to determine antigenic relationships to overseas isolates of ALV-J. STUDY DESIGN: Samples of blood, feather pulp, albumen and tumours were obtained from broiler breeder flocks which represented four genetic strains of meat chickens being grown in Victoria, South Australia, NSW and Queensland. Dead and ailing birds were necropsied on farm and samples were collected for microscopic and virological examinations. Virus isolation was carried out in C/O and DF-1 CEF cultures and ALV group specific antigen was detected in culture lysates using AC-ELISA. Micro-neutralisation assay was used for antigenic characterisation of selected isolates. Genomic DNA was isolated from cultured cells, tumours and feather pulp. ALV-J envelope sequences were amplified by PCR using specific ALV-J primers while antibodies against ALV-J were detected by ELISA. RESULTS: A total of 62 ALV-J isolates were recovered and confirmed by PCR from 15 (31.3%) of 48 breeder flocks tested. Antibody to ALV-J was detected in 20 (47.6%) of the 42 flocks tested. Characteristic lesions of myeloid leukosis caused by ALV-J were found in affected flocks. The gross pathological lesions were characterised by skeletal myelocytomas located on the inner sternum and ribs, neoplastic enlargement of the liver, and in some cases gross tumour involvement of the spleen, kidney, trachea, skeletal muscles, bone marrow, skin and gonads. Microscopically, the tumours consisted of immature granulated myelocytes, and were present as focal or diffuse infiltrations in the affected organs. Virus micro-neutralisation assays demonstrated antigenic variation among Australian isolates and to overseas strains of ALV-J. CONCLUSION: ALV-J infection was prevalent in Australian broiler breeder flocks during 2001 to 2003. Australian isolates of ALV-J show a degree of antigenic variation when compared to overseas isolates.     

Comb candidiasis affecting roosters in a broiler breeder flock

A cutaneous mycosis caused by Candida albicans that involved the combs and less frequently the wattles, facial skin, ear lobes, and neck of male broiler breeders is described. Roosters were 35 wk old and housed with hens in two conventional broiler breeder houses on a farm in western North Carolina. Morbidity was approximately 10% in one house and less than 2% in the other house. Mortality and flock fertility were not affected. Three birds from the most affected house were examined. All birds had white adherent material on their combs that presented as crusty patches or lighter diffuse areas. Often, lesions were roughly circular or had a defined margin. Small black scabs were present in a few lesions. Similar but less extensive lesions were located on the wattles, facial skin, ear lobes, and rictus. In one bird, lesions extended down the neck, and they were accompanied by hyperemia and feather loss. Hyperkeratosis with little to no inflammation and intralesional fungi occurring as yeast and pseudohyphae were seen microscopically. High numbers of C. albicans were isolated and identified from the lesions.     

Relationships of Body Weight,Feathering, and Footpad Condition with Reproductive and Carcass Morphology of End-of-Season Commercial Broiler Breeder Hens

Reproductive efficiency of broiler breeder hens declines with age. Whereas careful feed management can maximize BW uniformity at housing, there is variability in how rate of lay and flock behavioral dynamics will interact with subsequent growth during the breeder phase. This study characterized differences in carcass and reproductive morphology in end-of-cycle commercial broiler breeder hens based on BW, feather coverage, and footpad condition, and we discuss the potential implications of the findings. At 62 wk of age, 537 hens were studied from an original flock of 3,800. Birds were sorted into subgroups based on BW, feather score, footpad score, and whether they were in laying condition when dissected. The average flock BW was 3.56 kg, with means of 2.86, 3.56, and 4.20 kg for the low (LOW), standard (STD), and high (HIGH) BW groups, respectively. A higher proportion of birds from the STD (85%) and HIGH (81%) groups still had a fully formed reproductive tract compared with birds of the LOW (59%) group. The LOW birds in laying condition had a smaller ovary than the STD or HIGH birds. The ovary condition of birds in laying condition was not related to feather coverage. As feather coverage improved, final hen BW increased, demonstrating a potential role of feather coverage in growth efficiency or of BW in level of mating activity. Birds that received a feather score of 5 (complete back feather coverage) and had a normal reproductive tract made up 14.7% of this flock. It is likely that many of these birds were mating very infrequently or possibly not mating, which has implications for maintenance of flock fertility. Some may also have been returning from a molt. Footpad condition was not related to body size. External traits such as BW, feather score, and footpad score can provide insight into flock reproductive condition and male:female interaction.     

肉仔鸡对若干国产原料的氨基酸消化率

本试验研究了肉仔鸡性别与日龄对菜籽粕、棉籽粕、肉骨粉和羽毛粉的氨基酸消化率的影响。试验中测定了4周龄和6周龄的肉仔鸡公鸡和母鸡对菜籽粕、棉籽粕、肉骨粉和羽毛粉的氨基酸消化率。研究表明 ,除羽毛粉以外 ,4周龄肉仔鸡对其他3种原料的氨基酸真消化率显著高于6周龄肉仔鸡(P<0.01) ,肉仔鸡日龄对羽毛粉的氨基酸真消化率无影响。肉仔鸡性别对棉籽粕的氨基酸真消化率具有极显著影响(P<0.01) ,公鸡对棉籽粕的氨基酸真消化率极显著低于母鸡 ;性别对其它3种原料的氨基酸真消化率无显著影响。肉仔鸡性别与日龄对菜籽粕氨基酸真消化率存在极显著互作(P<0.01) ,对棉籽粕的氨基酸真消化率存在显著互作(P<0.05) ,且各种氨基酸消化率均表现出相同的变化趋势     

蒸煮酶解羽毛粉的营养价值及其在肉鸭上的能量和氨基酸利用率评定

本试验旨在研究采用真代谢能(TME)法评定3种蒸煮酶解羽毛粉对于肉鸭的能量和氨基酸营养价值,为合理开发和利用羽毛粉蛋白质资源提供基础数据。3种羽毛粉(Ⅰ~Ⅲ)分别为42日龄樱桃谷肉鸭羽毛粉、550日龄罗曼蛋鸡羽毛粉和100日龄三黄肉鸡羽毛粉。试验选取20只7周龄樱桃谷肉鸭,随机分为4个处理,每个处理5个重复,每个重复1只肉鸭,单笼饲养。处理1(T1)为测定羽毛粉Ⅰ,处理2(T2)为测定羽毛粉Ⅱ,处理3(T3)为测定羽毛粉Ⅲ,处理4(T4)为饥饿处理。试验期为7 d。结果表明:1)以干物质(DM)为基础,羽毛粉Ⅰ、Ⅱ、Ⅲ的总能(GE)分别为21.31、21.02和20.18 MJ/kg,表观代谢能(AME)分别为13.71、12.29和12.10 k J/kg,TM E分别为14.83、13.42和13.22 M J/kg。2)以DM为基础,羽毛粉Ⅰ、Ⅱ、Ⅲ的粗蛋白质(CP)含量分别为91.05%、87.31%和91.06%;羽毛粉Ⅰ、Ⅱ、Ⅲ的总氨基酸(TAA)含量都在80%以上,但不同羽毛粉的氨基酸含量差异较大。3)羽毛粉Ⅰ、Ⅱ、Ⅲ的TAA表观可代谢率分别为81.51%、73.07%和76.85%,TAA真可代谢率分别为85.09%、76.89%和80.43%。3种羽毛粉的表观可利用氨基酸和真可利用氨基酸含量也存在显著差异(P0.05)。由此可见,利用TM E法测定毛粉能量与氨基酸的营养价值,发现3种羽毛粉的代谢能(M E)、表观可利用氨基酸和真可利用氨基酸存在明显差异。羽毛粉Ⅰ的GE、ME、CP及TAA代谢率均高于羽毛粉Ⅱ和羽毛粉Ⅲ。     

饲粮蛋氨酸水平对43～63日龄黄羽肉鸡生长性能、胴体品质、羽毛蛋白质沉积和肉质的影响

本试验旨在研究饲粮中添加不同水平蛋氨酸对43～63日龄黄羽肉鸡生长性能、胴体品质、胴体和羽毛蛋白质沉积以及肉质的影响,并根据二次回归模型估测其蛋氨酸需要量.选用43日龄岭南黄鸡1 600只,按性别和体重分成10组(公母各5组),每组4个重复,每个重复40只.采用5×2(饲粮蛋氨酸水平×性别)两因子试验设计,饲粮蛋氨酸水...     

白羽肉鸡高效生产的营养调控研究进展

白羽肉鸡是一种快大型肉鸡,具有生长速度快和饲料转化率高等特点。影响白羽肉鸡生长性能的主要因素有遗传、营养、环境、管理等,白羽肉鸡高效生产与营养因素密不可分。本文基于白羽肉鸡生长发育规律,主要从能量、蛋白质(氨基酸)、矿物元素和维生素等营养需要及相关研究进行综述,旨在为白羽肉鸡高效生产提供参考依据。     

枯草芽孢杆菌制剂对肉鸡生长、胴体和鸡肉品质的影响

本文研究了枯草芽孢杆菌制剂对肉鸡生长性能、胴体和鸡肉品质的影响。选用90羽7日龄的肉仔鸡,随机分成3个处理组,每个处理设3个重复。对照1组饲喂基础日粮,对照2组饲喂基础日粮添加0.05%的硫酸新霉素制剂,试验组饲喂基础日粮添加0.1%的枯草芽孢杆菌制剂。试验期35d。试验结果表明:试验组肉鸡的末期平均体重、净增重和日增重均比对照1组高,且差异显著(P<0.05),但均比对照2组低,差异不显著(P>0.05)。试验组鸡的平均采食量均略高于两对照组(P>0.05),试验组的饲料转化率较对照1组提高3.14%,比对照2组低1.59%(P>0.05)。试验组肉鸡胴体品质的各项指标与两对照组相比,除了腿肌重和腿肌率有显著差异外(P<0.05),其余各项指标均无显著差异(P>0.05)。试验组鸡肌肉氨基酸总量、必需氨基酸和鲜味氨基酸含量均高于两对照组。这表明在较高的营养水平条件下添加枯草芽孢杆菌制剂对肉鸡生长具有一定的促进作用,对肉鸡胴体和鸡肉品质无不良影响,可增加鸡肉鲜味。     

Safety assessment of Bt 176 maize in broiler nutrition: degradation of maize-DNA and its metabolic fate.

Insect resistant Bt 176 maize has been developed by genetic modification to resist European borer infection. In the present investigation, the experiment was conducted to determine the effect of feeding a new hybrid of Bt 176 maize (NX 6262- Bt 176) on general health condition and performance of broiler chickens. Maize grains and diets were subjected to proximate analysis. Amino and fatty acids investigation were applied for both maize grains before used. To evaluate the degradation of NX 6262- Bt 176 maize DNA and its metabolic fate in broiler blood, muscles and organs. One-day-old male broilers were fed ad libitum on either an experimental diet containing NX 6262- Bt 176 or a control diet containing the non-modified maize grains for 35 days. Feed consumption and body weight were recorded weekly during the experimental period. All chickens were subjected to nutritional evaluation period at day 20 of age for 5 successive days, to calculate the percentage of apparent digestible nutrients in both diets. At day 35 samples were collected at several intervals after feed withdrawal. Prior to slaughter blood samples were collected from all birds by heart puncture to prevent DNA cross contamination. Samples from pectoral and thigh muscles, liver, spleen, kidney, heart muscle, bursa and thymus glands were collected. Digesta from different sections of the gastrointestinal tract (GIT) were collected as well. Packed cell volume (PCV) and some serum parameters were investigated. There were no significant differences between control and experimental group concerning chemical composition of feeds, apparent digestible nutrients, and all performance parameters measured (P > 0.05). Furthermore, there were no differences in the PCV and the analysed serum parameters between the control and experimental group. The results of maize DNA digestibility showed that the new variety takes the normal physiological passage along broiler GIT similar to the conventional line. In addition, Bt 176 maize DNA appears to be partially degraded in different parts of GIT comparable to the DNA of the control maize line. Results of the metabolic fate of maize DNA in broiler blood, muscles and organs indicated that only short DNA fragments (199 bp) derived from the plant chloroplast gene could be detected in the blood, skeletal muscles, liver, spleen and kidney, which disappeared after prolongation the fasting time. In heart muscle, bursa of Fabricius and thymus, no plant chloroplast DNA was found. Bt gene specific constructs from Bt 176 maize were not detected in any investigated blood or tissue samples.     

三黄种鸡产蛋期的生长模型的建立与分析

为了解三黄鸡产蛋期的生长发育规律,运用Logistic、Gompertz和von Bertalanffy 3种曲线模型分别对5～16月龄的三黄鸡体重数据进行拟合和分析。结果表明:3种模型均能很好地模拟三黄鸡产蛋期的生长情况,以Logistic模型拟合效果最佳。应用3种模型对三黄鸡产蛋期进行生长曲线拟合和分析是可行的。     

Genetic characterization of Thai indigenous chickens compared with commercial lines

A total of 210 chicken samples, from seven strains, were genotyped using 20 microsatellite loci of which 16 are recommended by the Food and Agriculture Organization. The genetic variability and divergence of four Thai indigenous strains and three commercial lines were assessed to generate baseline information for conservation, promotion, and make sustainable utilization of indigenous chicken resources in Thailand. A total of 227 alleles were distributed ranging from six (MCW 111) to 16 (MCW 183 and LEI 166) alleles per locus. The highest (0.81) and lowest (0.77) average of expected heterozygosities were observed in indigenous chicken (Dang) and commercial layer (Isa Brown), respectively. All microsatellite loci were in the Hardy–Weinberg equilibrium, except for MCW111 and ADL372 in the Isa Brown line. The subpopulation division coefficient (F _ST ) was strong with the value of 0.183 indicating the genetic differentiation among the studied groups. Four genetic clusters were detected: the first group consisted of layers (Isa Brown and White Leghorn); the second group was broiler; the third group consisted of non-black feather indigenous chicken (Chee, Dang, and Leung Hang Khoa); and the fourth group was black feather indigenous chicken (Pradu Hang Dam). The results of this study also suggested that Pradu Hang Dam is suitable to be developed as a meat type chicken due to lower genetic distance between Pradu Hang Dam and broiler.     

Preen gland function in layer fowls: factors affecting preen oil fatty acid composition

1. Preen oil derived from the preen gland has previously been shown to differ in its composition between birds of different ages, sex and diet. As a part of a larger study on preening behaviour and its components, the relative percentages of fatty acids in preen oil were examined in laying hens that differed in age, beak trimmed status, feather pecking status (pecker and pecked) and method of sampling (either direct from the preen gland or from lipid extracted from feathers). 2. Five experiments are described. Fatty acids extracted from lipid were analysed by gas chromatography (GC). Fatty acid composition was affected by age, by whether or not a bird was feather pecked (but not if it was a feather pecker) and by lipid source. 3. Changes in preen oil composition with age (shown here) may be due to changes in circulating concentrations of hormones. Differences in preen oil composition between feather pecked and non-pecked birds may influence plumage odour and therefore taste, making the plumage of some birds more attractive to pecking than others. 4. The proportions of some fatty acids derived from feathers differed to those extracted from the preen gland. Lipid found on feathers is most likely a combination of that from the preen gland and from sebaceous secretions from the skin.     

Analysis and Evaluation of Nutrient Composition of Muscles of Two Kinds of Mallard

This experiment was aimed to study the nutritional content and value of the muscles of two mallards (White feather mallard and mallard),and provide basic data and theoretical basis for the development and utilization of mallard meat products.60 White feathered mallards and mallards (30 for each breed,half of male and female) were chosen,and the composition and content of pectoral muscle crude protein,crude fat,cholesterol,amino acids,fatty acids,trace elements and vitamins were determined according to national standards and the nutritional values of muscle were evaluated.The results showed that the content of crude protein in muscle of White feather mallard was significantly lower than that of mallard (P<0.05).17 kinds of amino acids with contents higher than 0.01% were detected in the muscles of the two kinds of mallards,among which the contents of threonine,histidine,serine and proline in the muscles of the White feather mallard were significantly higher than those of mallard (P<0.05).The contents of lysine,glutamate and arginine were significantly lower than those of mallard (P<0.05).13 kinds of fatty acids with contents higher than 0.01% were detected,and the contents of stearic acid and oleic acid were significantly lower than those of the mallard.9 mineral elements (sodium,magnesium,potassium,calcium,manganese,iron,copper,zinc and selenium) in two kinds of mallards were detected,and there was no significant difference between the two kinds of mallards (P>0.05).8 kinds of vitamins were detected,and the content of vitamin B₁ in muscle of White feather mallard was significantly higher than that of mallard (P<0.05),but the contents of vitamin D and vitamin E were significantly lower than that of mallard (P<0.05).The ratio of amino acids in muscle of two kinds of mallards was close to the ideal model recommended by WHO,which was rich in mineral elements and vitamins for human body,and had a broad prospect of development and utilization.     

两种绿头鸭肌肉营养成分分析及评价

本试验旨在研究两种绿头鸭（白羽绿头鸭和绿头鸭）肌肉营养组成和价值,为绿头鸭肉产品的开发利用提供基础数据和理论依据。选择白羽绿头鸭和绿头鸭60只（每个品种各30只,公母各半）,依照国家标准测定胸肌粗蛋白质、粗脂肪、胆固醇含量及氨基酸、脂肪酸、微量元素和维生素的组成和含量,并对胸肌进行氨基酸评价及脂肪酸营养价值评价。结果显示,白羽绿头鸭肌肉粗蛋白质含量显著低于绿头鸭（P<0.05）;两种绿头鸭肌肉中均检测到17种含量大于0.01%的氨基酸,其中白羽绿头鸭肌肉苏氨酸、组氨酸、丝氨酸和脯氨酸含量显著高于绿头鸭（P<0.05）,赖氨酸、谷氨酸和精氨酸含量显著低于绿头鸭（P<0.05）;检测到13种含量均大于0.01%的脂肪酸,其中白羽绿头鸭硬脂酸和油酸含量显著低于绿头鸭（P<0.05）;检测到9种矿物质元素（钠、镁、钾、钙、锰、铁、铜、锌和硒）,两种绿头鸭差异不显著（P>0.05）;检测到8种维生素,白羽绿头鸭肌肉维生素B₁含量显著高于绿头鸭（P<0.05）,维生素D和维生素E含量显著低于绿头鸭（P<0.05）。两种绿头鸭肌肉氨基酸比例接近世卫组织推荐的理想模式,富含人体所需的矿物质元素和维生素,具有广阔的开发利用前景。     

Effect of magnesium on reactive oxygen species production in the thigh muscles of broiler chickens

1. The objective of the present study was to investigate the effect of magnesium (Mg) on reactive oxygen species (ROS) production in the thigh muscles of broiler chickens. A total of 96 1-d-old male Arbor Acre broiler chickens were randomly allocated into two groups, fed either on low-Mg or control diets containing about 1.2 g/kg or 2.4 g Mg/kg dry matter. 2. The low-Mg diet significantly increased malondialdehyde (MDA) concentration and decreased glutathione (GSH) in the thigh muscles of broiler chickens. ROS production in the thigh muscle homogenate was significantly higher in the low-Mg group than in the control group. Compared with the control, muscle Mg concentration of broiler chickens from the low-Mg group decreased by 9.5%. 3. Complex II and III activities of the mitochondrial electron transport chain in broilers on low-Mg diet increased by 23 and 35%, respectively. Significant negative correlations between ROS production and the activities of mitochondrial electron transport chain (ETC) complexes were observed. 4. The low-Mg diet did not influence contents of iron (Fe) or calcium (Ca) in the thigh muscles of broiler chickens and did not influence unsaturated fatty acid composition (except C18:2) in the thigh muscles. 5. A low-Mg diet decreased Mg concentration in the thigh muscles of broiler chickens and then induced higher activities of mitochondrial ETC, consequently increasing ROS production. These results suggest that Mg modulates the oxidation-anti-oxidation system of the thigh muscles at least partly through affecting ROS production.     

Dermatitis in broilers caused by Escherichia coli: isolation of Escherichia coli from field cases, reproduction of the disease with Escherichia coli O78:K80 and conclusions under consideration of predisposing factors

A dermatitis in broiler chickens, especially on the caudal back, thighs and around the cloaca is observed more frequently in the last years. The skin is swollen at sites of inflammation and a fibrineous plaque extends between muscle and subcutis. No clinical signs are visible in the living flock but the disease causes economical losses because of degrading and rejection of carcasses. Studies of literature and own field observations suggest that Escherichia (E.) coli is involved in the development of the dermatitis. The following serotypes were isolated from field cases: O78:K80 (3X), O2:K56 (2X), O127:K63 (3X), O9:K57 (1X), O140 (2X); two isolates could not be identified. The reproduction of the dermatitis was successful by infection via feather follicles with E. coli O78:K80. The density of broilers kept on farms may contribute to the outbreak of dermatitis by violation of the skin followed by infection of the injuries. Massage of the infected sites by close contact of birds and insufficient hygiene may support the development of the disease.     

A comparison of ileal digesta and excreta analysis for the determination of amino acid digestibility in food ingredients for poultry.

1. The apparent ileal and excreta digestibilities of amino acids in 15 samples representing 12 food ingredients were determined using 5-week-old male broiler chickens. The ingredients included 3 samples of cereals (wheat, maize and sorghum), 6 samples of plant protein meals (soyabean meal, cottonseed meal, canola meal and sunflower meal) and 6 samples of animal protein meals (meat meal, meat-and-bone meal, feather meal and fish meal). 2. The test ingredients were incorporated as the sole source of dietary protein in assay diets. Each diet was offered ad libitum to 3 pens (4 birds/pen) from d 35 to d 42 post-hatching. Total collection of excreta was carried out during the last 4 d. All birds were killed on d 42 and the contents of the lower half of the ileum were collected. Apparent ileal and excreta amino acid digestibilities were calculated using acid-insoluble ash as the indigestible marker. 3. The influence of site of measurement was found to vary among food ingredients, among samples within an ingredient and among different amino acids within an ingredient. Ileal amino acid digestibility values were similar in some ingredients, but significantly lower or higher in others than the corresponding excreta values. 4. Average ileal and excreta amino acid digestibilities in sorghum and maize were similar, but significant differences were observed for individual amino acids. In contrast, ileal amino acid digestibility values were higher than the corresponding excreta digestibility values in wheat. 5. The average ileal and excreta digestibilites of amino acids in the 3 soyabean meal samples were similar although small, but significant differences were noted for individual amino acids. Site of measurement had no effect on the digestibility of amino acids in canola meal. Digestibilities of valine, isoleucine, phenylalanine, histidine, glutamic acid, alanine and tyrosine in sunflower meal and those of valine, methionine, isoleucine, leucine, lysine, glutamic acid and alanine in cottonseed meal were lower by excreta analysis. 6. Digestibilities in animal protein meals, with the exception of blood meal and fish meal, were consistently higher by excreta analysis. Ileal-excreta differences in individual amino acid digestibilities were more evident in feather meal, meat meal and meat-and-bone meal. 7. Threonine and valine were the indispensable amino acids that were more frequently influenced by the site of measurement. Of the dispensable amino acids, aspartic acid, serine, glutamic acid and alanine were the most affected. 8. Differences determined between ileal and excreta digestibilities in the present study clearly demonstrate that amino acid metabolism by hindgut microflora in chickens may be substantial and that digestibilities measured in the terminal ileum are more accurate measures of amino acid availability than those measured in the excreta.