利用析因法测定产蛋鸡必需氨基酸需要量、模式及模型

本研究是3期饲养试验内容的概括和总结，目的是使所建立的估测产蛋鸡必需氨基酸（EAA）需要模型具有广泛的适应性和准确性。对394只罗曼蛋鸡的试验数据进行多元回归分析。根据食入的每个EAA（主要包括赖氨酸、蛋氨酸、色氨酸、苏氨酸、亮氨酸、异亮氨酸、苯丙氨酸、缬氨酸、组氨酸、精氨酸、胱氨酸、酪氨酸）与产蛋、维持和增量所需的相应EAA的回归关系，测定相应的回归系数，建立了估测每个EAA需要的数学模型，可估测产蛋鸡在任何生产条件下每个EAA的需要量及模式。另外．本试验还建立了指数曲线模型（R2为0．71），唐它来描述食入EAA与产蛋量间的关系比较恰当，不过，用来估测产蛋鸡EAA需要量时，其估测值与实测值的吻合度没有桥因法好（R2为0．80）。     

不同水平生物素对鸡生产性能的影响

生物素在动物的生长、繁殖、生产以及疾病防治等方面发挥着重大作用。本文主要研究了生物素与肉仔鸡增重和料肉比之间的关系、生物素与产蛋鸡产蛋率之间的关系以及生物素与生长鸡屠宰性能之间的关系,并提出了各种鸡日粮中生物素的最适添加量。     

Effects of ad libitum feeding on performance of different strains of broiler breeders

(1) Tolerance to ad libitum feeding was compared in three genotypes of broiler breeder hens: a standard broiler breeder fed ad libitum (SA) or restricted (SR), a slow growing 'label' broiler breeder (L) and an experimental dwarf heavy broiler breeder (E). Two similar experiments were conducted in two distinct research centres. (2) Feed intake and body weight were measured every 3 weeks from hatch to 40 to 49 weeks of age. Egg production and egg abnormalities were recorded. The number of yellow follicles in ovaries was counted at the age of 32 weeks. (3) Body weight was stabilised at 2.2, 3.7 and 5.4 kg after 24 weeks of age in L, E and SA hens, respectively. Growth of the SR hens was similar to that of L up to 20 weeks and stabilised at a similar level to that of E hens after 30 weeks of age. (4) Sexual maturity was delayed by 6 weeks in restricted breeders compared to ad libitum fed hens that started to lay at 20 weeks. SA hens had low egg production and a high proportion of defective eggs, which was largely compensated for by feed restriction. However, productivity of SR hens remained lower than that of L breeders. (5) Compared to the low viability and reproductive fitness observed with SA hens, the E dwarf broiler breeder tolerated ad libitum feeding and had better egg production, fewer egg abnormalities and yellow follicles per ovary and a higher egg production. However, laying rate was still lower than that of the SR and L groups. Energy conversion (kJ/g egg) from 32 to 40 weeks of age was much higher in the SA group than in the other three groups. 6. The feasibility of feeding a dwarf broiler breeder ad libitum calls for further research on implications of specific IGF and GH-receptor expression at the level of the ovary in dw chickens.     

Optimum threonine requirement of laying hens

1. One experiment was conducted with medium weight laying hens to determine their threonine requirement between 28-38 weeks. 2. Two threonine-limiting diets of identical protein quality (summit-dilution) were used and, by dilution, ten protein contents were produced supplying 2.7 to 5.4 g total threonine/kg diet. The diet with the lowest protein was also supplemented with synthetic L-threonine. Each diet was fed to 5 groups of 24 laying hens. 3. The daily threonine requirement of the individual laying hens was estimated by direct methods to be 8.7 mg/g egg output plus 43.49 mg/kg body weight for this experiment. Calculated optimum intakes of threonine for various ratios of costs of input to value of output are tabulated. For example, for a flock of medium weight laying hens producing an average of 50 g daily egg mass, the optimum threonine intake (mg/hen d) varied between 700 and 710 for cost ratios (k-values) varying between 0.002 and 0.001.     

Amino acid nutrition in egg production industry

The egg production industry is facing various problems that need to be solved. For amino acid nutrition to achieve scientific and economical feeding of laying hens, it is necessary to elucidate the content, digestibility, or availability of nutrients of feedstuffs and feeds and the requirement of amino acids for laying hens. In addition, improvement to quality of eggs and meat of spent hens, methods of management and development of new feedstuffs are essential. For sustainable animal production, decrease in excreta and animal welfare should be studied. The real‐time determination of content and digestibility of amino acids in feedstuffs are essential for formation of feeds. Recent advances in the near infrared reflectance analysis will be able to determine the content, digestibility and availability of nutrients in feedstuffs and feeds, if we have a supplemental amount of conventional analysis to define the calibration population. The amino acid requirements are affected by various factors. Therefore the method to quickly and exactly determine amino acid requirements in response to various factors is necessary. By using plasma free amino acid concentration as a criterion, it is possible to determine amino acid requirements in various conditions of laying hens within a short experimental period, repeatedly using the same animals. Because the amino acid requirements differ among individual animals, it should be expressed as grams per hen per day. Practically, it is impossible to formulate various feeds for individual hens. The various expressions have been developed and these expressions have advantages and disadvantages. The nitrogen excretion of laying hens is easily reduced by reducing dietary nitrogen levels and restricting the feed intake. The availability of amino acid may be improved by feeding management, and supplementing enzyme, but the quality of eggs and meat of spent hens and welfare of laying hens are not affected by amino acid nutrition.     

Effect of graded nitrogen supplements on egg protein synthesis and body protein retention in broiler hens

In the top laying period (29th/30th week of life) egg protein synthesis and protein retention in the bodies of laying hens were ascertained. Based on egg-N analyses, the relation between N-intake/live weight0.67kg and egg-N discharge/kg LW0.67kg was regressively calculated and described. The subtraction of egg-N discharge/LW0.67kg from N-balance/LW0.67kg made it possible to estimate N-retention/LW0.67kg in the body. From the intersection of this curve with the chi-axis it follows that the broiler hen meets the N-requirement for maintenance and egg production with a daily consumption of 1,264.7 mg N/LW0.67kg, which corresponds to 15.8 g crude protein, and then neither loses nor retains body protein. At a daily intake of this amount of CP (15.8 g) the broiler hen produces 44.1 g egg per day. An energy intake of more than 70 EFUhen/animal and day resulted in fat retention in the broiler hen.     

Preliminary investigation on the nutritive value of krill meal in the feed of broiler chickens and laying hens.

Krill meal was used as a protein feed in rations for broiler chickens and laying hens and its nutritional effectiveness was studied in comparison with conventional feed-stuffs of animal origin. In experiments with 650 broiler chickens from 1 to 28 and from 29 to 56 days to fattening krill meal was added to the standard feedmixture in lieu of fish meal, and dried skim-milk, and at higher levels also in lieu of soyabean oilmeal. In the experiment with 22 layer hens kept in individual cages 3% of the fish meal were substituted by 3% of krill meal. The performance of chickens fed on diets with krill meal was lower in comparison with analogical groups fed on fish meal. Higher levels of krill meal, exceeding 15 and 11% in the first and second period of feeding respectively, reduced the weight gains and feed intake of chickens. The fatty acid C14, C18 and C18:1 content of internal body fat was changed in chickens fed on higher levels of krill meal. In the experiment with hens krill meal decreased the feed efficiency, the pigmentation of egg yolks, however, was more intensive and the vitamin A content of yolks was increased in comparison with the control group. The results show that krill meal can be used as a partial substitute of fish meal in the feed of broilers and hens.     

Optimum isoleucine requirement of laying hens and the effect of age

1. Medium weight laying hens were used for an assay to determine their isoleucine requirement between 26 and 36 weeks of age and again between 46 and 56 weeks of age. 2. Two isoleucine-limiting mixtures were formulated with similar amino acid profiles, one containing 198 g and the other 110 g crude protein per kg diet. These mixtures were blended to give a series of 11 diets with isoleucine contents ranging from 7.6 to 3.8 g/kg. The lowest protein diet was also fed with a supplement of L-isoleucine. Each of the 12 diets was given to 5 groups of 24 laying hens. 3. The daily isoleucine requirement of individual laying hens was estimated to be 9.48 mg/g egg output plus 44.47 mg/kg body weight per day for the 1st period and 12.11 mg/g egg output plus 6.86 mg/kg body weight per day for the 2nd period. Calculated optimum intakes of isoleucine for various ratios of cost of input to value of output are tabulated. For example, for a flock of medium weight hens producing an average of 50 g daily egg mass, the optimum isoleucine intake (mg/hen d) varied between 760 and 890 varying for ratios of costs to egg prices. 4. It is concluded that the isoleucine required per day does not decrease during the first laying year despite a decrease in rate of egg output.     

Nonwithdrawal Molting Programs

In the commercial egg industry the management practice of using feed withdrawal to induce a flock to molt has been under extreme scrutiny. This is because animal rights groups have voiced their concern about using this practice. Thus, about 5 yr ago, the United Egg Producers (UEP) commissioned 5 universities to conduct experiments to develop alternative molting programs that used nonwithdrawal feeding programs to molt laying hens. The studies conducted to date used techniques ranging from feeding hens without added salt in the diet to using readily available, low-cost feed ingredients to develop molt diets that are low in energy level and protein content. The results of these studies indicated that molting laying hens without feed withdrawal could be done successfully. Research at the University of Illinois found that feeding laying hens diets consisting of wheat middlings, soybean hulls, and corn (low protein and low energy) were successful in providing for acceptable postmolt egg production performance and economic benefit compared with using a standard feed withdrawal method. Therefore, after 5 yr of experimenting with nonwithdrawal molting methods done in several university settings, the egg industry has successfully adopted these methods of molting laying hens. In addition, based on the finding of these experiments, the UEP has revised their recommended molting guidelines to state that only nonwithdrawal molting methods will be permitted after January 1, 2006. Thus, these guidelines will apply to approximately 82% of the US egg industry.     

Estimation of potassium and magnesium flows in animal production in Dianchi Lake basin,China

The objectives of this study were to estimate and evaluate potassium (K) and magnesium (Mg) budgets and flows of animal production in the basin of Dianchi Lake, China. Feed sampling and farmer interviews were conducted in field surveys. The supplies of K and Mg from local and external feeds and the retention, production and excretion of animals were calculated individually for dairy cows, fattening pigs, breeding sows, and broilers and laying hens. The K and Mg flows on a regional level were estimated using the individual budgets. At the individual level, in dairy cattle, the K and Mg supplied from local feeds accounted for large parts of the total nutrient intakes, whereas in the other animal categories most of the K and Mg in the feeds depended on external resources. Our findings also suggested that excessive Mg intake resulted in high Mg excretion and low use efficiency in dairy cattle and fattening pigs. At the regional level, the K and Mg amounts of manure produced and applied in the area (K: 339 and Mg: 143 t/year) exceeded those used as local feeds. Our results imply the animal production potentially increased the K and Mg loads in the regional agriculture system.     

日粮添加维生素A对肉鸡和蛋鸡生长性能及免疫功能的影响

试验研究了不同的维生素A(VA)添加水平对肉鸡和蛋鸡的生长性能及机体免疫功能的影响.试验选用1日龄的雌性蛋鸡和雌性肉鸡各270只,分别随机分成3个处理,每个处理6个重复,每个重复15只,分别饲喂含维生素A 0(对照)、4 000和20 000 IU/kg的日粮,饲养试验时间为84 d.试验结果表明,日粮添加维生素A为0 IU/kg处理的肉鸡和蛋鸡的采食最显著高于添加维生素A的各处理(P＜0.05);日粮维生素A添加水平对肉鸡和蛋鸡的免疫器官指数(胸腺指数、脾脏指数和法氏囊指数)无显著影响(P＞0.05);对照的肉鸡和蛋鸡异嗜粒细胞/淋巴细胞(H/L)高于其他处理(P＞0.05);肉鸡和蛋鸡绵羊红细胞(SRBC)抗体滴度和新城疫(ND)抗体滴度随着日粮维生素A添加水平的升高而升高;日粮添加4 000 IU/kg维生素A处理的肉鸡和蛋鸡钥孔戚血蓝蛋白(KLH)抗体滴度、白蛋白浓度和白介素-2(IL-2)的浓度最高.蛋鸡的免疫器官指数和血清白蛋白浓度显著高于肉鸡(P＜0.05);肉鸡和蛋鸡的其他免疫指标差异不显著(P＞0.05).综上所述,日粮添加4 000 IU/kg维生素A能提高肉鸡和蛋鸡的生长性能和免疫功能,当添加水平达到20 000 IU/kg时,可对生长性能和免疫机能产生不利影响.肉鸡和蛋鸡的主要免疫指标没有最著差异.     

Live Performance and Immune Responses of Straight-Run Broilers: Influences of Zinc Source in Broiler Breeder Hen and Progeny Diets and Ambient Temperature During the Broiler Production Period

Supplemental zinc in broiler diets has been reported to be more available to the chick when provided as a zinc-amino acid complex rather than an inorganic source. Previous work with broiler breeder and turkey hens has indicated that supplementing diets with zinc-amino acid complexes enhances immune status and livability of progeny. This study examined the effects of supplemental dietary zinc source [ZnSO₄ or Availa Zn 100 zinc-amino acid complex (ZnAA)] provided to broiler breeder hens and their progeny on live performance and immune status of broilers. Broiler breeder and progeny diets were supplemented with 160 and 140 ppm zinc, respectively. In addition to the dietary treatments, the broilers were subjected to either optimum or suboptimum temperatures during the first weeks of production. Supplementing broiler breeder hen and progeny diets with ZnAA and ZnAA + ZnSO₄, respectively, improved cumulative feed conversion (FC) of broilers. Providing diets supplemented with ZnSO₄ to hens or exposing broilers to optimum temperatures enhanced humoral immune response of progeny. Subjecting broilers to suboptimum brooding temperatures increased feed intake, but a higher incidence of mortality occurred primarily encompassing the first week of the growout. These data indicate that brooding temperature affected broiler performance, whereas the response to dietary zinc source was less pronounced.     

The broiler breeder paradox: ethical, genetic and physiological perspectives, and suggestions for solutions

1. Due to intensive selection, broiler chickens became the most efficient meat-producing animals because of their fast growth, supported by a virtually unlimited voluntary feed intake. These characteristics cause many problems in the management of broiler breeder hens because of the negative correlation between muscle growth and reproduction effectiveness. 2. This problem, namely the fast muscle growth versus reproduction health paradox, induces a second paradox, acceptable reproduction and health versus hunger stress and impaired welfare, because broiler breeder hens require dedicated programmes of feed restriction (1) to maximise egg and chick production and (2) to avoid metabolic disorders and mortality in broiler breeders. 3. Given that poultry selection is a global large-scale business and chickens are a prolific species, improvement in profit can only be obtained by selecting on feed conversion and/or for higher breast meat percentage, which will intensify the broiler-breeder paradox. 4. New feeding strategies are being studied, but it is questionable if the paradox can be solved by management tools alone. Because breeding and selection are long-term processes, involving animals, farmers, consumers, industry, environment etc., a more sustainable breeding goal needs to be determined by a multidisciplinary approach and an open debate between several actors in the discussion. 5. Using dwarf broiler breeder hens could be one alternative, because dwarf hens combine relatively good reproductive fitness with ad libitum feeding. Another possibility is to accept lower broiler productivity by assigning economic values to welfare and including integrity traits in an extended breeding goal.     

Effect of yeast cell wall supplementation in laying hen feed on economic viability,egg production,and egg quality

Yeast cell walls can strengthen the immune system and promote agglutination of gastrointestinal tract pathogens, thereby improving animal health and productivity. This study evaluated the effect of supplementing the diet of commercial laying hens with 0, 225, 450, or 900 ppm of yeast cell wall supplement on hen productive performance, egg quality, and economic viability. Yeast cell wall supplementation increased the feed intake, egg production, egg mass, albumen height, and Haugh unit score. Shell thickness and yolk color also were affected by the treatments. The economic viability analysis demonstrated that although feeding costs more with supplementation, the production of more eggs is possible, resulting in a greater than proportional increase in the gross margin. Thus, yeast cell wall supplementation had beneficial effects on the productive performance of laying hens, improved the internal and external egg quality, and contributed to greater profitability.     

Effect of daily feed intake in laying period on laying performance, egg quality and egg composition of genetically fat and lean lines of chickens

1. The objectives of this study were to evaluate the effects of feed intake on laying performance, egg quality and egg composition in a Fat line and a Lean line during the laying period (34 to 54 weeks of age). 2. The experiment was a 2 × 2 factorial design with two dietary intake levels (nutrition recommendation and 75% of recommendation) and two broiler genotypes (Fat line and Lean line). Hens (384 of each line) were randomly divided at 23 weeks of age into 4 treatments, with each treatment represented by 12 replicates of 16 birds each. The experiment started when the rate of lay reached 5% and continued until 54 weeks of age. 3. The results indicated that there was a significant interaction between daily feed intake and genotype on egg production, egg weight, percentage yolk, yolk/albumen ratio and yolk cholesterol content. Fat line hens produced significantly more eggs and had a lower incidence of cracked eggs than the Lean line hens. The reduction in feed intake decreased egg weight and increased egg production, egg-shape index and cholesterol content of yolk significantly.     

Dietary selenium increases vitamin E contents of egg yolk and chicken meat

1. The influence of different forms of dietary selenium (Se) on vitamin E (alpha-tocopherol) and Se contents of egg yolk and chicken meat was investigated. 2. Eggs were collected from laying hens subjected to 4 different dietary treatments after 24 weeks of age. Treatments compared the effects of inorganic Se supplementation (selenite) to those of organic (Se-enriched yeast, Se-enriched alga Chlorella) supplements. In a second experiment the effect of the above organic dietary Se supplementation on the alpha-tocopherol contents of meat from broiler chickens was evaluated. 3. Dietary Se supplementation increased the alpha-tocopherol content of egg yolks from 297 mg/kg dry matter in treatment without supplementation to 311 mg/kg when selenium was supplemented as selenite, and to 370-375 mg/kg when organic supplements were used. The Se and alpha-tocopherol contents of breast and thigh meat in broilers were significantly increased by organic dietary Se supplementation. 4. The inclusion of organic dietary Se sources in the diets of laying hens and broilers would enhance the nutritional value (vitamin E and Se contents) of products (eggs and meat) for human consumption.     

Protein utilization as well as crude protein and amino acid requirements of broiler hens

After N-balance experiments with broiler hens in the top laying period and the feeding of soybean coarse meal/fish meal protein the protein utilisation values were calculated. The PNu curve and the PEW curve could be described as utilisation values from the N-retention curve (e-function). At an intake of N at which the hen neither decomposed nor retained protein, the utilisation (PNu) for maintenance and egg production was 55.3% and the utilisation of feed protein for egg production 49.4%. Maximum PEW 34.3% could only be ascertained at an N-intake/LW0.67kg of 1500 mg. The corresponding crude protein quota of 18.7 g recommended as crude protein requirement is calculated from this N-quota (xm) and a live weight of the broiler hen of 2804 g. For the same N-quota (xm) and the same live weight of the hens this results in a necessary quota of S-AA of 694 mg per hen and day. Provided the daily feed intake is 145 g and thus the intake of crude protein 18.7 g and that of S-AA 694 mg per hen, the necessary crude protein content of the feed is 130 g per kg original substance and an S-AA concentration which is equivalent to 3.7% of the crude protein (in g/16 g N).     

The effect of egg formation and laying on the food and water intake of brown leghorn hens

Food and water intakes of four caged Brown Leghorn hens were studied on a daily and hourly basis in relation to egg formation. In addition the food intake of two similar hens was studied using a Skinner box which provided a more detailed record of ingestive behaviour in a non‐social situation in which social interactions might not mask the relationship between food intake and physiological needs. Food intake was greater on days on which ovulation occurred than on days during which there was neither ovulation nor oviposition. Water intake was greater on days during which ovulation occurred than on days with oviposition but no ovulation. On this latter type of day (laying day) food intake was greater than on days without ovulation and oviposition (resting day). Both food and water intakes were depressed for 1 to 2 h before oviposition, but ingestion increased during the hour of laying and remained high for 1 to 2 h.     

肉鸡能量需要量预测模型的研究进展

能量摄入对肉鸡的生长具有重要作用。肉鸡能量代谢受多种因素的影响,如性别、环境温度、活重、采食量等。建立肉鸡能量需要模型,对于改善饲料效率,提高经济效益具有重要的作用。本文就肉鸡能量需要预测模型的重要性、不同模型的比较及存在的问题和发展方向四方面进行综述。     

高温环境对家禽营养物质消化的影响

高温环境是影响家禽生产的一个重要因素,高温环境下家禽采食量降低,肉鸡生长速度减慢,蛋鸡产蛋率、蛋重及体重下降。高温环境影响家禽生产性能并非全部由于采食量下降引起的,即使在相同采食量的条件下,高温环境仍显著降低家禽的生产性能。本文针对高温环境对家禽营养物质消化代谢以及消化酶活性、肠道结构、饲粮排空速度等方面的影响进行归纳总结,为进一步了解高温环境对家禽消化吸收功能的影响及其营养调控提供科学依据。