不同种类有机酸对肉鸡生长性能、养分利用率和肠道菌群的影响研究

本试验研究不同种类有机酸对肉鸡生长性能、养分利用率和肠道菌群的影响。将240只1日龄艾维茵肉鸡随机分为4个处理(对照组、1.5%柠檬酸组、1.5%延胡索酸组、0.2%复合酸化剂组),每个处理6个重复,每个重复10只鸡。在试验17～20d和38～41d分别进行代谢试验;在试验第21天和第42天进行屠宰试验。结果表明:肉鸡日粮中添加1.5%柠檬酸、1.5%延胡索酸和0.2%复合酸化剂不同程度改善肉鸡生产性能;提高前期阶段饲粮能量和养分的利用率;对42日龄盲肠内容物的pH值有一定影响,同时,柠檬酸和复合酸化剂能显著促进肉鸡42日龄直肠乳酸杆菌的增殖;综合分析所有参数,0.2%复合酸化剂的作用效果最优。     

有机硒和枣粉对肉仔鸡生长性能及养分利用的影响

为探究有机硒和枣粉对肉仔鸡生长性能及养分利用的影响,试验采用2×5两因子（A、B）随机试验设计,A因子为枣粉添加水平,分别为0、8%,B因子为硒添加水平,分别为 0、0.3、0.6、0.9、1.2 mg/kg。选择体重接近、健康的1日龄科宝505白羽肉仔鸡720只,随机分为 10组,每组 6 个重复,每个重复 12 只鸡（公母各半）。试验期为 42 d,分前期（0 ～ 21 d）和后期（22 ～ 42 d）两个饲养阶段。结果表明：有机硒和枣粉两因子间对肉仔鸡生长性能和养分利用均无显著的交互作用（P > 0.05）。试验前期,A2组平均日增重显著高于A1组（P < 0.05）,且A2组料重比显著低于其他各组（P < 0.05）|添加枣粉可显著提高肉仔鸡平均日采食量和料重比（P < 0.05）。试验后期,A5组平均日增重显著高于除A1组外的其他各组（P < 0.05）,而料重比显著低于除A3组外的其他各组（P < 0.05）,A4组平均日采食量显著高于A1、A2和A3组（P < 0.05）。A5组总能和总磷利用率均有下降的趋势（P =0.090|P =0.078）。添加枣粉后,肉仔鸡对氮和钙的利用率均有改善（P < 0.05）,但总能的利用率显著下降（P < 0.05）。综上,饲粮添加0.3 mg/kg硒可以提高肉仔鸡前期平均日增重,添加枣粉可改善肉仔鸡前期采食量,并提高氮和钙的利用率。 [关键词] 肉鸡|枣粉|有机硒|生长性能|养分利用     

Potential of blended organic acids to improve performance and health of broilers infected with necrotic enteritis

Organic acids (OA) and their blends have been shown to positively affect performance and health of broilers. However, the data in the literature are not consistent. This study examined the potential of blended short-chain fatty acids (SCFA) with medium-chain fatty acids (MCFA) as alternatives to antibiotic growth promoters (AGP) on performance, health and welfare of broilers infected with necrotic enteritis (NE). The additives used were: A) a blend of SCFA, MCFA, and a phenolic compound (SMP); B) a blend of free and buffered SCFA with MCFA (SMF); C) a blend of free and buffered SCFA with a high concentration of MCFA (SHM). A total of 1,404 Ross 308 one-day-old male parental chicks were randomly distributed into 78-floor pens with 13 replicates of 18 birds each. Six treatments were the following: T1, unchallenged control (UCC); T2, challenged control (CHC); T3, challenged group plus zinc bacitracin (BAC); T4, challenged group plus additive SMP; T5, challenged group plus additive SMF; T6, challenged group plus additive SHM. Challenged birds were gavaged with Eimeria spp. on d 9 and Clostridium perfringens EHE-NE18 on d 14. Post NE challenge and cumulatively, BWG, FCR, and nutrient digestibility of birds were compromised (P < 0.05) by NE challenge indicating a successful induction of sub-clinical NE. Additive SHM had higher BWG compared to CHC and BAC groups (P = 0.001; d 10 to 24) but not different from SMP and SMF groups (P > 0.05). All the 3 additive groups had lower FCR compared to CHC (P = 0.001; d 0 to 35), and exhibited similar jejunal lesions (d 16) compared to BAC and apparent ileal protein digestibility (d 21) compared to UCC and BAC groups (P > 0.05). Birds in additive SHM group had a higher concentration of serum IgA compared to all groups (P = 0.001) except additive SMF (P > 0.05; d 21). All the additive groups had lower footpad dermatitis and hock burns compared to CHC (P < 0.05). The findings suggest the potential of blended OA as alternatives to BAC to protect broilers from NE indicated by improved FCR, immunity, digestibility, and bird welfare.     

Growth performance of fast-growing broilers reared under different types of production systems with outdoor access: Implications for organic and alternative production systems

Outdoor access is an important part of organic and free-range poultry production, yet limited information exists on the effect of various housing and production systems on growth performance and colonization of food-borne pathogens. Therefore, the primary purpose of the current study was to evaluate the influence of different housing systems, particularly fixed versus small, portable houses, with and without outdoor access to pasture, on seasonal growth performance, leg quality, and presence of bacterial food-borne pathogens. In the current study, we used fast-growing broilers, as many small producers use commercial broilers due to their carcass conformation and high breast yield compared with slow-growing hybrids or standard heritage breeds. Although interest in alternative genetics exists because they may be more adapted to outdoor production, they require longer growing periods, with accompanying labor and cost. A pasture containing a mixture of forages was used to simulate the conditions common for small farms in the local region. The experiment had 4 treatment groups: (1) small, portable hoop houses with access to pasture, (2) small, portable hoop houses without access to pasture, (3) a fixed house with access to the outdoors, and (4) a fixed house without access to the outdoors. The present study was repeated at different times of the year to determine if a seasonal effect on the consumption of pasture and carcass quality was present. Overall, raising birds in hoop houses resulted in a reduced growth rate compared with birds raised in the fixed house. None of the production systems altered bone strength or feed conversion. Food-borne pathogens commonly associated with poultry were not found in any of the environments tested. Seasonal production was an issue in the small hoop house birds, as extreme heat in the summer resulted in early termination of that trial. Expanding on forage choice in pastures and customizing hoop houses to deal with weather fluctuations, especially in regions where extreme heat may affect production, are important considerations for these systems.     

Antibiotics promote abdominal fat accumulation in broilers

Antibiotics stimulate the growth of animals but result in drug residues and bacterial resistance. In this study, the negative effect of antibiotics on abdominal fat deposition was evaluated in broilers. The results showed that adding both chlortetracycline (50 g/1,000 kg) and tylosin (50 g/1,000 kg) significantly increased abdominal fat weight, abdominal fat percentage (p < .05), and triglyceride and cholesterol levels (p < .05) in blood. Also, both products synchronously stimulated intestinal absorption and synthesis of liver fat. The expression levels of the peroxisome proliferator‐activated receptor γ (PPARγ), diacylgycerol acyltransferase 2 (DGAT2), lipoprotein lipase (LPL), and fatty acid‐binding protein (FABP4) genes in abdominal fat tissue significantly increased (p < .05 or 0.01) when antibiotics were added to the feed. However, no significant difference was found in expression of the fatty acid synthesis (FAS) or acetyl CoA carboxylase (ACC) genes. Further in vitro study results revealed that antibiotics had no effect on fat content or the related gene expression levels in preadipocytes. In summary, the antibiotics induced fat deposition in adipose tissues by activating extracellular absorption of fatty acids from intestinal absorption and synthesis of liver fat. However, it shows no direct regulation by adipose tissue.     

Effects of a protected inclusion of organic acids and essential oils as antibiotic growth promoter alternative on growth performance,intestinal morphology and gut microflora in broilers

This experiment was conducted to investigate the effects of protected essential oils and organic acids mixture on poultry feeding. A total of 450 1‐day‐old Cobb 500 chicks were randomly allotted into three treatments with six replicates. Birds were offered a basal diet (C), basal diet with 0.15 g/kg enramycin premix (A) and basal diet with 0.30 g/kg protected essential oils and organic acids mixture product (P). The results showed that protected essential oils and organic acids mixture supplementation reduced average daily feed intake and ratio of feed to gain (F/G) at 22–42 days of age, and F/G during 1–42 days of age also declined (P < 0.05). Product supplementation improved spleen index, villus height and crypt depth of the jejunum at 42 days when compared with the control (P < 0.05). In addition, secretory immunoglobulin A level of ileal mucosa and trypsin and chymotrypsin activities of intestinal tract were higher in the P treatment. Bacterial sequence analysis of the intestinal tract revealed that protected essential oils and organic acids mixture supplementation changed gut microflora mainly in Lactobacillus. These data suggested that dietary mixture of organic acids and essential oils addition could be used in the poultry industry as an antibiotic growth promoter alternative.     

The Effects of a Natural Antibiotic Alternative and a Natural Growth Promoter Feed Additive on Broiler Performance and Carcass Quality

The use of subtherapeutic levels of antibiotics in poultry feed improves performance and morbidity in broiler chickens. However, consumer pressure related to the potential development of antibiotic-resistant bacteria has resulted in the development of nonantibiotic feed additives that may also improve broiler performance. Essential oils, organic acids, and phytogenic compounds enhance production of gastric secretions, stimulate blood circulation, and reduce levels of pathogenic bacteria. The objective of the current study was to assess the use of Biostrong 505+ and Biostrong 510 as natural growth promoters in broiler chickens. Assessment was based on the performance and carcass quality of broilers fed either a maximum-yield or a least-cost commercial broiler diet. The maximum-yield diet improved broiler performance and carcass quality. Biostrong 505+ can be used to improve feed conversion and breast yield when incorporated into diets devoid of antibiotics. This improvement in feed conversion and breast yield was accentuated when Biostrong 505+ was used in conjunction with a maximum-yield diet. Biostrong 510 improved feed conversion when used in poultry diets containing antibiotics.     

Performance and welfare of broilers as affected by stocking density and zinc bacitracin supplementation

The influence of stocking density (16, 20 and 24 birds/m²) and zinc bacitracin (0 or 100 mg/kg) on the performance, carcass characteristics and some indirect welfare indicators of broilers were examined in a 35‐day trial. The weight gain, feed intake, liveability and carcass characteristics of broilers grown at densities of 16, 20 and 24 birds per m² were similar (P > 0.05). Over the whole trial period, however, feed per gain of birds at the highest density (24 birds/m²) was higher (P < 0.05) than those at the other two densities. Litter quality was poorer at high population densities, but there were no welfare implications as indicated by the lack of effect of density on gait scores and the incidence of hock and fat pad burns. Inclusion of zinc bacitracin improved weight gains and feed intake of broilers over the 35‐day trial period at all three stocking densities tested. Zinc bacitracin supplementation had no influence on the feed per gain of birds reared at densities of 16 and 20 birds/m², but improvements were observed at a density of 24 birds/m². The relative weights of lymphoid organs (spleen and bursa) were lowered (P < 0.05) with increasing density, suggesting a greater degree of stress on the birds. Zinc bacitracin supplementation had no influence on bursa weights of birds reared at densities of 16 and 20 birds/m², but increased the bursa weights of birds reared at a density of 24 birds/m². Overall, these data indicate that, with the removal of in‐feed antibiotics in the future, care should be taken when considering population densities of greater than 20 birds/m².     

红车轴草异黄酮对肉鸡生产性能及肉品质的影响

为了研究红车轴草（Trifolium pratense）异黄酮对肉鸡生长、屠宰性能及肉品质的影响,将180羽1日龄AA肉仔鸡分成3组,即对照组、试验Ⅰ组、试验Ⅱ组,分别饲喂基础日粮、基础日粮+红车轴草异黄酮(10 mg/kg)、基础日粮+红车轴草异黄酮(20 mg/kg)。结果显示,红车轴草异黄酮可以提高肉鸡的日增体质量（P<0.05）和屠宰性能（P>0.05）,降低血清中甘油三酯、总胆固醇和腹脂率（P<0.05）,减少了储存第6天肉中丙二醛含量（P<0.05）,降低了肉品滴水损失和剪切力（P>0.05）。表明红车轴草异黄酮能够提高肉鸡生长性能和屠宰性能,改善肉品品质,添加20 mg/kg时肉鸡日增长速度最快。     

Efficacy of l-glutamic acid,N,N-diacetic acid to improve the dietary trace mineral bioavailability in broilers

Trace minerals are commonly supplemented in the diets of farmed animals in levels exceeding biological requirements, resulting in extensive fecal excretion and environmental losses. Chelation of trace metal supplements with ethylenediaminetetraacetic acid (EDTA) can mitigate the effects of dietary antagonists by preserving the solubility of trace minerals. Lack of EDTA biodegradability, however, is of environmental concern. l-Glutamic acid, N,N-diacetic acid (GLDA) is a readily biodegradable chelating agent that could be used as a suitable alternative to EDTA. The latter was tested in sequential dose–response experiments in broiler chickens. Study 1 compared the effect of EDTA and GLDA in broilers on supplemental zinc availability at three levels of added zinc (5, 10, and 20 ppm) fed alone or in combination with molar amounts of GLDA or EDTA equivalent to chelate the added zinc, including negative (no supplemental zinc) and positive (80 ppm added zinc) control treatments. Study 2 quantified the effect of GLDA on the availability of native trace mineral feed content in a basal diet containing no supplemental minerals and supplemented with three levels of GLDA (54, 108, and 216 ppm). In study 1, serum and tibia Zn clearly responded to the increasing doses of dietary zinc with a significant response to the presence of EDTA and GLDA (P < 0.05). These results are also indicative of the equivalent nutritional properties between GLDA and EDTA. In study 2, zinc levels in serum and tibia were also increased with the addition of GLDA to a basal diet lacking supplemental trace minerals, where serum zinc levels were 60% higher at the 216 ppm inclusion level. Similar to the reported effects of EDTA, these studies demonstrate that dietary GLDA may have enhanced zinc solubility in the gastrointestinal tract and subsequently enhanced availability for absorption, resulting in improved nutritional zinc status in zinc-deficient diets. As such, GLDA can be an effective nutritional tool to reduce supplemental zinc levels in broiler diets, thereby maintaining health and performance while reducing the environmental footprint of food-producing animals.     

Effects of non-antibiotic feed additives on performance, tibial dyschondroplasia incidence and tibia characteristics of broilers fed low-calcium diets

This experiment was conducted to investigate and compare the efficacy of different feed additives on performance, tibial dyschondroplasia (TD) incidence and tibia characteristics of male broilers fed low-calcium diets. A completely randomized design, with six treatments and five replicates of five chicks per each was used. Experimental treatments were: (i) Basal diet containing recommended level of calcium (0.9%) as control treatment (Ctrl), (ii) low-calcium (0.67%) diet without any additive (LC), (iii) low-calcium diet + probiotic (2 g/kg diet), (iv) low-calcium diet + prebiotic (2 g/kg diet), (v) low-calcium diet + synbiotic [mix of probiotic and prebiotic (each 2 g/kg diet)], (vi) low-calcium diet + organic acid (1.5 g/kg diet). Birds were reared in an open-sided house system under natural tropical condition until 21 days of age. Feeding with low-calcium diet negatively influenced broiler performance (body weight, body weight gain and feed conversion ratio) and tibia characteristics, whereas dietary inclusion of all feed additives had beneficial effects on above-mentioned parameters and helped the birds to overcome problems related to low-calcium diets. Different treatments had no effect on TD incidence.     

The effect of genotype,choice feeding,and season on organically reared broilers fed diets devoid of synthetic methionine

In response to the impending ban on synthetic methionine in organic poultry diets, researchers have focused on finding alternative strategies to supply this amino acid. The objectives of this study were to assess performance and carcass characteristics of broilers fed diets devoid of synthetic methionine by using 1) a slow-growing and a fast-growing genotype, 2) choice-feeding management (supplying grain and a complementary premix in 2 separate feeders), and 3) pasture access and seasonal variation. Inclusion of fish meal and high percentages of soybean meal enabled the specific genotype methionine requirement to be met. All diets were certified organic. The experiment was conducted during the grower and finisher phases in 4 different seasons: late fall, spring, summer, and early fall. Pasture access was assessed either by housing broilers on the West Virginia University Organic farm and giving them outdoor access, or by housing broilers on the West Virginia University Animal Sciences farm and giving them no outdoor access. Fast-growing genotypes were superior in performance and carcass characteristics compared with slow-growing genotypes, and choice-feeding management did not improve performance or carcass characteristics. Pasture access tended to have no effect on slow-growing broilers and decreased the performance of fast-growing broilers. Performance was decreased in late fall, likely because of cold ambient temperatures.     

Effects of berberine on the growth performance,antioxidative capacity and immune response to lipopolysaccharide challenge in broilers

This study evaluated the effects of berberine on growth performance, immunity, haematological parameters, antioxidant capacity, and the expression of immune response‐related genes in lipopolysaccharide (LPS)‐challenged broilers. We assigned 120 one‐day‐old male broilers (Ross 308) to two treatment groups; each group included two subgroups, each of which included six replicates of five birds per replicate. The experiment used a 2 × 2 factorial arrangement with berberine treatment (0 or 60 mg/kg dietary) and challenge status [injection of saline (9 g/L w/v) or LPS (1.5 mg/kg body weight)] as the main factors. On days 14, 16, 18 and 20, broilers were intraperitoneally injected with LPS or physiological saline. Blood and liver samples were collected on day 21. Dietary berberine supplementation significantly alleviated the compromised average daily gain and average daily feed intake (p < 0.05) caused by LPS. The LPS challenge led to increased lymphocyte and white blood cell (WBC) counts, malondialdehyde (serum and liver) content, and immunoglobulin G and M, tumour necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β) expression (p < 0.05) and significantly reduced serum total superoxide dismutase (T‐SOD) activity (p < 0.05). Dietary berberine significantly mitigated the LPS‐induced decreases in the mRNA expression of nuclear factor‐kappa B (NF‐κB), TNF‐α, IL‐1β, inducible nitrite synthase and cyclooxygenase‐2 (p < 0.05) in the liver. In conclusion, berberine supplementation has a positive effect on LPS challenge, which may be related to the increase in antioxidant enzyme activity and inhibition of both NF‐κB signalling and the expression of inflammatory mediators.     

乳酸杆菌制剂对肉仔鸡肠道菌群、血清球蛋白及生产性能的影响

120只1日龄艾维茵肉仔鸡饲喂不同水平乳酸杆菌制剂,研究乳酸杆菌制剂对肉仔鸡的饲喂效果。结果表明,乳酸杆菌制剂在提高肉仔鸡成活率、增重和改善饲料利用率方面有一定的促进作用,但效果不显著(P>0.05)。而在改善肠道菌群结构和提高血清球蛋白方面效果显著(P<0.05)。     

Effects of using a chicken-origin competitive exclusion culture and probiotic cultures on reducing Salmonella in broilers

Three commercial products, a partially defined chicken-origin competitive exclusion culture (Aviguard, 0.50 mL/chick) and 2 single-organism probiotic cultures (Saccharomyces cerevisiae, Levucell SC, 1 g/kg of feed, and Pediococcus acidilactici, Bactocell, 100 mg/kg of feed) were evaluated for their ability to reduce Salmonella in broilers and their effects on production performance. It was found that all the treatments significantly (P < 0.05) reduced Salmonella concentrations, as compared with the control, on the chicken, in the ceca, and on the chicken carcass. In addition, it was found that these treatments had no adverse effect on any of the production parameters that were measured. Finally, this study showed the importance of using these preharvest treatments as part of an integrated program to control Salmonella at the broiler farm.     

牛膝对肉鸡生产性能与免疫器官指数的影响

试验选择48羽12日龄快大黄肉仔鸡随机分成3组,在试验组的基础日粮中分别添加0%、0.4%和0.8%的牛膝,试验期30 d,研究牛膝对肉鸡生产性能与免疫器官指数的影响。结果表明,与对照组相比,Ⅰ组45日龄肉鸡平均日采食量、日增重显著提高(P<0.05),料重比显著降低(P<0.05);此外,与对照组相比,Ⅰ组30日龄法氏囊、脾脏指数,45日龄脾脏指数显著提高(P<0.05),Ⅱ组45日龄脾脏指数显著提高(P<0.05)。研究提示,合理使用牛膝不仅可以提高肉鸡的生产性能,还能有效促进免疫器官的生长发育,其适宜添加量为0.4%。     

甘露寡糖对肉鸡生长性能及肠黏膜形态的影响

选择120只1日龄肉鸡随机分为2组,试验组添加0.3%的甘露寡糖。每组6个重复,每个重复10只。每组基础日粮相同。试验结果表明:试验后期(4~5周龄)和整个试验期(0~5周龄)的增重,添加0.3%甘露寡糖组显著高于对照组(P<0.05),试验前期(0~3周龄)未见明显效果。试验前期的料肉比,添加0.3%甘露寡糖组显著低于对照组(P<0.05),试验后期和整个试验期处理组虽然均低于对照组,但无显著差异。添加0.3%甘露寡糖组回肠绒毛长度以及绒毛长度与隐窝深度之间的比值均显著高于对照组(P<0.05)。添加0.3%甘露寡糖可显著提高肉鸡的生长性能,并可以改善肠黏膜的形态,增大小肠吸收面积。     

大豆异黄酮对肉鸡生产性能和胴体品质的影响

试验选用100只21日龄AA肉鸡,随机分为4组,即对照组和3个试验组,每个组设5个重复。对照组饲喂基础日粮,试验组在基础日粮中分别添加3、6、9mg/kg的有效大豆异黄酮。试验结果表明,肉鸡日粮中添加大豆异黄酮对肉鸡生产性能影响差异不显著(P>0.05);31日龄试验组血清中尿酸含量平均比对照组低29.25%(P<0.05);42日龄试验组腹脂垫重/体重比对照组平均低9.50%(P<0.05)。