The influence of dietary protein and antimicrobial feed additives on salmonella carriage by broiler chickens

Salmonella carriage in broiler chickens was not apparently influenced by the protein concentration of the ration, pelleting or by the coccidiostat monensin. The inclusion of penicillin in the diet was associated with an increase in salmonella shedding, particularly in the first half of the rearing period, but did not influence the lactobacillary count in the crop or the pH of the contents of the crop, gizzard and caecum. Furazolidone medication (150 mg/kg food) for the first 10 days had no effect on salmonella carriage at the time of slaughter (seven weeks) and studies into the influence of growth promoting antibiotics (avoparcin, bacitracin and virginiamycin) on salmonella shedding were inconclusive. Circumstantial evidence indicated that the food was the most probable source of infection for the birds studied in these experiments.     

应用HACCP管理,控制饲料中沙门氏菌

沙门氏杆菌与沙门氏杆菌症对畜禽生产及人类健康的威胁已受到公众的重视。沙门氏菌(SALMONELLA)是肠杆菌常见的一种重要病原性菌属,已知的沙门氏菌血清有2499个,在自然界中广泛分布,几乎所有的血清型皆会污染食物以致发病,该菌污染饲料后,不仅引起动物中毒,造成菌血症,     

商品肉鸡限饲技术

随着肉鸡育种技术的不断发展,肉鸡生长速度愈来愈快。目前国内塑料大棚及其它简陋鸡舍的环境条件与肉鸡的生长发育极不相适应,增重与成活率的矛盾表现的更加突出。考虑到目前国内鸡舍的现实条件,找到肉鸡生长发育的适应原点,现对肉鸡限制饲喂技术进行阐述,期望对广大肉鸡饲养者有所裨益。 1 肉鸡徒长的负影响 1.1 鸡只生长过快,体重的增长与骨骼发育不平衡,导致腿病 肉鸡育种存在着体重迅速增长和骨骼、内脏器官发育缓慢的矛盾。现代育种技术的进步,使肉鸡生长速度越发加快,这一矛盾就更加突出。肉鸡体重增加较快,而鸡腿、脚的骨骼发育缓慢,致使腿脚承受体重压力过大,造成肉鸡腿、脚病的发生。     

早期限饲对肉仔鸡的影响

遗传育种选育和营养水平的改进,在使肉仔鸡生长速度不断提高的同时带来了一系列负面影响,如脂肪沉积、代谢性疾病、骨骼疾病、死亡率增加。早期限饲在改善这些问题上有一定的作用。本文综述了早期限饲对肉仔鸡的生产性能和健康状况等影响,并对早期限饲的进一步研究方向进行了展望。     

Influence of age on the apparent ileal amino acid digestibility of feed ingredients for broiler chickens

The apparent ileal digestibility of amino acids in 8 feed ingredients was determined using 14-, 28- and 42-d-old male broiler chickens. The ingredients included three cereals (wheat, sorghum and maize), one cereal by-product (mill run), three oilseed meals (canola, cottonseed and soybean meals) and one animal protein meal (meat and bone meal). Dietary crude protein in the assay diets was supplied solely by the test ingredient. All diets contained 20 g/kg acid-insoluble ash as an indigestible marker, and each diet was offered ad libitum in mash form to 5 replicate pens from 11 to 14 d, 25 to 28 d and 39 to 42 d post-hatching. There were 12, 6 and 6 birds per pen for the 14, 28 and 42 d samplings, respectively. The results suggest that the age of broilers significantly influenced the apparent ileal digestibility of amino acids. The effects, however, varied among amino acids and ingredients. In wheat, the digestibility of most amino acids was higher in 14- than in 28- and 42-d-old broilers. In maize, the digestibility coefficients of amino acids were higher at 28 and 42 d than at 14 d. The digestibility coefficients in maize and wheat at 28 and 42 d were similar. The digestibility of amino acids in sorghum at 42 d was higher than those at 28 d, but similar to those at 14 d except for histidine, lysine, serine and glycine, which were significantly higher at 42 d. Digestibility of amino acids in sorghum was similar between 14 and 28 d except for isoleucine, leucine, phenylalanine, glutamic acid and alanine. The digestibility of amino acids in mill run at 42 d was significantly higher than those at 14 and 28 d. There were no differences in digestibility between 14 and 28 d. In general, the digestibility of amino acids in canola meal, soybean meal and, meat and bone meal was higher at 28 and 42 d compared to those at 14 d, and similar between 28 and 42 d of age. In cottonseed meal, age had no effect on the digestibility coefficient of amino acids, except for lysine and arginine, which increased with age. Analysis of the combined results for the 8 feed ingredients showed that, in general, the digestibility coefficients of amino acids increased with advancing age of broiler chickens.     

Failure of drinking water sanitisation to reduce the incidence of natural salmonella in broiler chickens

The addition of a sanitiser, containing a mixture of organic acids and other approved additives, to water offered to broiler chickens was effective in eliminating salmonella from the drinking water. However, it failed to influence salmonella carriage by the chickens which were still shedding salmonella at market age (seven weeks old).     

Linkage between the intestinal microbiota and residual feed intake in broiler chickens

Background: Intestinal microbiota plays a key role in nutrient digestion and utilization with a profound impact on feed efficiency of livestock animals. However, the intestinal microbes that are critically involved in feed efficiency remain elusive.Methods: To identify intestinal bacteria associated with residual feed intake(RFI) in chickens, male Cobb broiler chicks were individually housed from day 14 to day 35. Individual RFI values were calculated for 56 chickens.Luminal contents were collected from the ileum, cecum, and cloaca of each animal on day 35. Bacterial DNA was isolated and subjected to 16 S rRNA gene sequencing. Intestinal microbiota was classified to the feature level using Deblur and QIIME 2. High and low RFI groups were formed by selecting 15 and 17 chickens with the most extreme RFI values for subsequent LEfSe comparison of the difference in the microbiota. Spearman correlation analysis was further performed to identify correlations between the intestinal microbiota composition and RFI.Results: No significant difference in evenness, richness, and overall diversity of the microbiota in the ileum, cecum,or cloaca was observed between high and low RFI chickens. However, LEfSe analysis revealed a number of bacterial features being differentially enriched in either high or low RFI chickens. Spearman correlation analysis further identified many differentially enriched bacterial features to be significantly correlated with RFI(P 0.05). Importantly,not all short-chain fatty acid(SCFA) producers showed a positive association with RFI. While two novel members of Oscillibacter and Butyricicoccus were more abundant in low-RFI, high-efficiency chickens, several other SCFA producers such as Subdoligranulum variabile and two related Peptostreptococcaceae members were negatively associated with feed efficiency. Moreover, a few closely-related Lachnospiraceae family members showed a positive correlation with feed efficiency, while others of the same family displayed an opposite relationship.Conclusions: Our results highlight the complexity of the intestinal microbiota and a need to differentiate the bacteria to the species, subspecies, and even strain levels in order to reveal their true association with feed efficiency. Identification of RFI-associated bacteria provides important leads to manipulate the intestinal microbiota for improving production efficiency, profitability, and sustainability of poultry production.     

Oral salmonella antigens for the control of salmonella in chickens

Multivalent antigen preparations of sonicated lyophilized cells derived from up to 6 different salmonella serotypes were added in decreasing levels to broiler feed throughout the broiler's life. Several preliminary experiments challenging chicks via contaminated feed with some of the homologous serotypes showed that salmonellae were cleared more rapidly from treated chicks than from untreated controls and that fewer isolations of salmonellae were made from their ceca.     

Changes in feed consumption and water intake among broiler chickens subjected to melatonin treatment during the hot-dry season

Tropical Animal Health and Production - The experiment was conducted to evaluate changes in feed consumption and water intake among broiler chickens subjected to melatonin treatment during the...     

不同水平的蛋氨酸对感染球虫(E.tenella)肉仔鸡的影响

试验采用3×2试验设计。将7日龄360只AA肉仔鸡按称重均匀分成6组(Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ),每组60只鸡,每5只鸡一笼,饲养在不锈钢笼中。A处理为日粮蛋氨酸添加水平0%(A1)、0.2%(A2)、0.8%(A3),B处理为孢子化柔嫩艾美耳球虫(E.tenella)卵囊(B1——接种3×104个孢子化柔嫩艾美耳球虫卵囊,B0——未接种)。其中Ⅰ、Ⅱ组饲喂试粮1(A1),Ⅲ、Ⅳ组饲喂试粮2(A2),Ⅴ、Ⅵ饲喂试粮3(A3)。14日龄时,Ⅰ、Ⅲ、Ⅴ组鸡,每只分别接种3×104个孢子化柔嫩艾美耳球虫卵囊,22日龄试验结束。结果表明:①日粮中添加蛋氨酸与未添加蛋氨酸比,可以显著提高日增重(P<0.05),且日粮中添加0.8%的蛋氨酸与0.2%的相比,对试验期间肉仔鸡的生产性能的影响差异不显著(P>0.05);②日粮蛋氨酸水平对肉仔鸡血糖影响不大;③日粮蛋氨酸水平可以显著影响感染球虫的肉仔鸡的病变记分(P<0.05),即日粮中添加0.8%的蛋氨酸,显著优于0.2%组、0%组(P<0.05)。因此,在球虫感染的情况下,高营养水平对其是有效的。     

Pathogenicity and control of Eimeria mitis infections in broiler chickens.

The pathogenicity of two strains (B4 and C2) of Eimeria mitis was studied using young broiler chickens. Both strains of coccidia were pathogenic, and C2 strain was more virulent than B4. Growth of the broilers was depressed as early as day 3 postinoculation (PI), but the depression was greatest during days 5 and 6 PI. Feed conversion and shank skin pigment of the young broiler chickens were concomitantly affected by infections of E. mitis. Infection subsided by day 7 or 8 PI and was accompanied by a compensatory growth. The drugs effective against the infections were halofuginone, lasalocid, monensin, and nicarbazin. The least efficacious were zoalene and amprolium plus ethopabate.     

Suitability of poultry litter ash as a feed supplement for broiler chickens

An experiment was conducted to evaluate poultry litter ash (PLA) at graded levels (0, 25, 50, 75, and 100%) as a dietary substitute for dicalcium phosphate (dicalP) for broiler chickens, where PLA was substituted for dicalP on a wt/wt basis. A decreased BW gain was observed at 21 d from PLA at the 100% substitution rate when compared with the 25% substitution rate. No effects on BW gain, feed consumption, or FCR were incurred by study termination at 41 d, and the 100% substitution rate of dicalP did not cause any detrimental effects on the live performance in market age broilers. Although femur ash percentages decreased with increasing levels of PLA, bone integrity was not compromised by the addition of PLA to the diet. Dry matter digestibility of dietary Ca (26.32–58.65%) and P (30.23–42.68%) increased with increasing levels of PLA (0–100%), respectively, inferring that the Ca and P component of the diet was more efficiently used as the level of PLA increased. In conclusion, PLA resulting from the combustion of poultry litter can be used as a P and Ca source for broilers.     

Fumaric and sorbic acid as additives in broiler feed

The aim of the experiment was to study the effect of dietary organic acids, fumaric and sorbic, on nitrogen corrected apparent metabolisable energy (AME(N)), metabolisability of nutrients, endogenous losses and performance on young broiler chickens. A total of 56 male Ross broilers were used in a growing experiment from 14 to 30d age. Seven experimental wheat-based (655g/kg) diets were formulated. The control diet did not contain organic acids. The other six diets were produced with the addition of fumaric or sorbic acids, replacing 0.5% , 1.0% or 1.5% of the wheat. The organic acid supplemented diets contained higher levels of AME(N) compared to the control diet. Overall, birds offered organic acids had lower feed intake. Dietary organic acids did not significantly affect weight gain or feed efficiency, however, birds offered supplemented diets had lower numbers of Lactic acid bacteria and Coliforms in the ileum and caeca. Birds offered organic acids had lower levels of endogenous losses compared to control fed birds. There was a negative relationship between AME(N) of the diets and excreted endogenous losses, measured as sialic acid. It can be concluded that the decrease in secretions from the gastrointestinal tract in the presence of fumaric and sorbic acids may be a mechanism involved in the mode of action of dietary organic acids.     

Effect of acidified feed on susceptibility of broiler chickens to intestinal infection by Campylobacter and Salmonella

Consumption of poultry meat is associated with human Campylobacter and Salmonella infections. One way to control the presence of these bacteria in broiler flocks is to make chickens less susceptible for colonisation. Acidification of feed may be a tool to reduce the Campylobacter and Salmonella carriage in broiler chickens. In the present experiments an acidified feed with high levels of organic acid, 5.7% lactic acid and 0.7% acetic acid, was applied. In an in vitro experiment the reduction or growth of Campylobacter and Salmonella was measured after addition of 10(7)cfu of these bacteria into a conventional broiler feed, acidified feed and fermented feed, whereas the numbers of Salmonella increased in non-acidified feed. The number of Campylobacter decreased 2-3 (10)log cfu. In the acidified and fermented feed a complete reduction of Campylobacter was observed within 20 min, and a total Salmonella reduction started after 1h, and was complete after 2h. Subsequently, an in vivo experiment with 100 individually housed broiler chickens showed that chickens fed acidified feed were less susceptible to an infection with Campylobacter than were chickens fed conventional feed. The size of reduction was however limited. The susceptibility for Salmonella colonisation was not affected by acidified feed. It is concluded that the role for acidified feed in the control of Campylobacter and Salmonella is limited.     

Effect of decreased feed intake on serum and pancreatic alpha-amylase of broiler chickens

Removal of feed from 20-day-old broiler chicks for 24 hours caused serum and pancreatic alpha-amylase activities to increase almost twofold. A 24-hour feeding period following feed removal caused a reduction in serum alpha-amylase to basal levels and a sixfold reduction in pancreatic alpha-amylase activity. Serum alpha-amylase levels remained elevated after long-term feed restriction in adult broilers compared with levels in full-fed controls. Reduction in feed intake in chicks caused by coccidial infections also resulted in increased serum alpha-amylase. In all cases, the degree of change in serum alpha-amylase corresponded inversely to feed intake. It is proposed that the pancreas synthesizes a specific quantity of alpha-amylase, which does not change even under conditions of extended underconsumption of feed. The rate of alpha-amylase secretion is determined, at least indirectly, by the rate of carbohydrate metabolism, and the remainder of the enzyme is stored in the pancreatic cells. A small percentage of the stored enzyme diffuses into the blood and thus directly reflects increased secretion or accumulation of alpha-amylase in the pancreas in response to conditions of carbohydrate utilization.     

Effect of amino acid deficiency on precaecal amino acid digestibility in broiler chickens

In this study, we determined whether deficient dietary amino acid (AA) concentrations influence the precaecal (pc) AA digestibility when determined using the regression approach. We mixed two basal diets. Basal diet 1 was deficient in essential AAs, whereas adequate AA concentrations were ensured in basal diet 2 by adding free AAs. Rapeseed cake and full‐fat soya beans as test ingredients were included in the basal diets at levels of 100 and 200, and 150 and 300 g/kg, respectively, at the expense of maize starch. Each diet was tested with six replicates of 10 broiler chickens each. The feed intake of the chickens that were fed diets based on basal diet 2 was similar, whereas the feed intake of the chickens that were fed diets based on basal diet 1 differed considerably. The numerical differences in pc AA digestibility determined with basal diet 1 or 2 ranged from 2.6 percentage points to 20.8 percentage points in rapeseed cake and from 0.5 percentage points to 15.2 percentage points in soya beans. Across all measured AAs, the average differences were 10.1 percentage points and 5.4 percentage points in rapeseed cake and soya beans, respectively. The differences in the estimated pc AA digestibility between the basal diets were probably caused by different basal endogenous AA losses in the digesta between treatments as a consequence of different feed intake. Adequate AA concentrations and test ingredient levels that are specifically adjusted to avoid a negative effect on feed intake are recommended for future studies.