肉鸡饲养营养需要及配方技术研究进展

本文综述了肉仔鸡营养需要量、饲料效价评定及配方设计技术等方面研究进展.研究表明:(1)肉鸡饲养阶段的划分从3个阶段过渡到4个阶段更为科学;(2)营养需要规格呈现多元化趋势,将与肉鸡品种、环境、追求的生产目标及饲料原料本身的评价体系等相结合;(3)若将饲料养分的标准差即变异引入配方模型的系数矩阵,可明显提高配方养分实际达成的概率;(4)用标准化回肠可消化率氨基酸配制日粮,可提高对肉鸡生产性能的预测水平.     

猪饲料营养价值评定及营养需要的研究进展

本文针对猪饲料营养价值评定、营养需要量及配方设计技术等方面的研究进行了总结.研究表明:(1)猪饲料能量的评定指标正从消化能、代谢能体系过渡到净能体系;氨基酸生物学效价指标从表观消化率过渡到具有实际应用价值的标准化回肠氨基酸消化率等.(2)在猪的营养需要量的研究方法上,从过去的列表法向以影响猪养分需要的各种参数为驱动的数学模型预测养分过渡,在营养需要的指标上增加了净能和标准化回肠氨基酸需要量等.且新增的养分指标纳入配方设计与饲养实践条件基本具备.     

猪饲料和营养研究进展

作者针对猪饲料营养价值评定、营养需要量及配方设计技术等方面,概述了当前的进展与趋势。猪饲料能量的评定指标正从消化能、代谢能体系过渡到净能体系;氨基酸生物学效价指标从表观消化率过渡到具有实际应用价值的氮校正回肠氨基酸消化率等。在猪的营养需要量的研究方法上,从过去的列表法向以影响猪养分需要的各种参数为驱动的数学模型预测养分过渡,在营养需要的指标上增加了净能和氮校正回肠氨基酸需要量等,且新增的养分指标纳入配方设计与饲养实践条件基本具备。     

肉鸡营养中标准回肠可消化氨基酸

氨基酸标准回肠消化率的概念克服了用肉公鸡强饲法测定带来的缺点。迄今为止,已测定了常用饲料原料和饲用晶体氨基酸的必需氮基酸的标准回肠消化系数。使用原料的标准回肠可消化氨基酸及基于标准回肠消化率的氨基酸营养推荐值配制饲料,与基于总氨基酸配制的日粮相比,肉鸡生产性能及生产效益有所提高。     

肉鸡营养需求量及对生长影响的研究进展

本文综述了近十年来我国肉鸡对能量、蛋白质和氨基酸、矿物质元素、维生素四种营养物质的营养需求量及对生长影响的研究进展。结果表明,目前我国对肉鸡营养的研究在饲粮能量和蛋白质两大营养素方面已经得到较系统化的研究,对氨基酸、矿物质元素和维生素等微量营养物质的研究成为当今的热点。     

肉鸡铁营养需要量的研究进展

铁是所有动物的必需微量元素.本文综述了肉鸡铁的营养代谢,营养需要量的研究方法、研究现状、影响因素以及存在的问题和今后的研究方向.     

肉鸡蛋氨酸的营养研究与应用

日粮中蛋氨酸水平对肉仔鸡生产性能有着重要的影响。Kino等（１９８６）和Carew等（１９９７）研究表明：与其它必需氨基酸不足相比，蛋氨酸缺乏时对肉仔鸡的生长抑制最为严重。在蛋氨酸不足的日粮中添加蛋氨酸以提高肉仔鸡生长性能已达到共识，并在生产实践中广泛应用（Lin１９９６）。有关蛋氨酸的营养研究历来受到人们重视，目前它仍是畜禽氨基酸营养研究的一个热点，现将肉仔鸡蛋氨酸营养研究与应用情况阐述如下。１蛋氨酸的生理功能蛋氨酸的生理功能是多方面的，有人统计，动物体内有８０种以上的生化反应需要蛋氨酸的参与。动物体内…     

肉鸡蛋氨酸营养研究进展

蛋氨酸是肉鸡的第一限制性氨基酸,一直是家禽营养研究的重要内容。特别是近几年来甜菜碱的出现、可利用氨基酸概念的应用,国内外对这一方面进行了大量的研究。１　蛋氨酸的营养作用蛋氨酸在动物机体内作为必需氨基酸,不但作为体内蛋白质合成原料,而且参与体内重要的代谢过程,如参与肾上腺素合成胆碱,具有抗脂肪肝作用。有保肝解毒功效,在体内转换成胱氨酸、半胱氨酸、提供硫等。肉鸡缺乏蛋氨酸时,会出现发育不良,肌肉萎缩,体重减轻,皮毛变质,无光泽,肾肝功能减弱,啄羽,啄肛等症状。蛋氨酸在很大程度上能影响动物的免疫机能,…     

Effect of Phytase Supplementation in Diets on Nutrient Digestibility and Performance in Broiler Chicks

A performance trial was conducted with broiler chicks to study the effect of phytase (PHY) supplementation in diets formulated with reduced AME, Ca, and P. The nutrient digestibility was determined during the 14- to 21-d and 28- to 35-d periods. The treatments consisted of 3 diets (NC1, NC2, NC3) differing in nutrient content and each diet with or without supplemental PHY (NC1, 0 or 500; NC2, 0 or 750; NC3, 0 or 1,000 U of PHY/kg feed) and 1 positive control diet (PC). Compared with the PC diet, negative control diets (NC) resulted in lower AME and apparent ileal amino acid digestibility for some amino acids. Phytase supplementation of the NC diets increased AME, apparent ileal amino acid digestibility, and apparent ileal crude protein digestibility. Phytase addition also increased mineral absorption in 21- and 35-d-old broilers fed NC diets. Reduced nutrient digestibility appears to be a factor in the weight gain and feed intake results. Reducing Ca and P content reduced feed intake in a stepwise fashion in the NC diets. Phytase increased feed intake and generally improved nutrient digestibility, which resulted in an increase in digestible nutrient intake. Averaged across NC diets, PHY improved body weight. Bone-breaking strength was the most consistent predictor of Ca and P reduction. All NC diets had significantly lower bone-breaking strength than the PC. Phytase supplementation of the NC diets gave bone-breaking strengths that were comparable to the PC. Diets with PHY had the highest bioeconomic index.     

Estimation of Nutrient Equivalency Values of Natuzyme and Its Effects on Broiler Chick Performance

Two experiments were carried out to estimate nutrient equivalency of a commercial multi-enzyme (Natuzyme) and its effects on broiler chick performance. Experiment 1 was carried out using a completely randomized design to evaluate the response of chicks to Natuzyme (with different equivalency values assigned by the producer) in corn-soybean meal-based diets. Dietary treatments 1 and 6 were negative and positive controls, respectively. Diets 2 through 5 were graded levels of nutrient equivalency values of Natuzyme. Each diet was offered to 5 replicates of 16 chicks (n = 480). In experiment 2, a total of 480 male Ross 308 broiler chicks were used in a completely randomized design. Treatment 1 to 4 varied in ME, CP, and nonphytate P content, but in all cases, the ratio between these nutrients remained constant, and treatments 5 to 8 included graded levels of Natuzyme from 0.1 to 0.4 g/kg. Results of experiment 1 show that multi-enzyme supplementation could not restore chick performance to the levels equal to positive control. Equivalency values of Natuzyme for ME, nonphytate P, and CP obtained were 195,180 kcal/kg and 188.45 and 1,170%, respectively. As obtained in the first experiment, performance of chicks in the second experiment showed that Natuzyme did not liberate nutrient equivalency values recommended by the producer for broiler chicks when fed corn-soybean meal-based diets.     

Effect of dietary crude protein level on basal ileal endogenous losses and standardized ileal digestibilities of crude protein and amino acids in newly weaned pigs

The study was carried out to estimate basal ileal endogenous crude protein and amino acid losses (IAAL_B) and standardized ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) originating from casein in newly weaned pigs from linear relationships between ileal recoveries and dietary intakes of graded levels of CP and AA. A total of 14 (12 + 2 for replacement) 3‐week‐old barrows weighing 5.7 kg was fitted with simple T cannulas at the distal ileum. At 28 days of age, the pigs were randomly allocated to the six experimental diets with two pigs per diet in four weekly repeated measurements. Corn starch‐based diets, containing six graded levels of CP from casein (90, 155, 220, 285, 350, 415 g/kg CP as‐fed basis respectively), were formulated. Titanium dioxide (TiO₂) was included as a digestibility marker. Each experimental period consisted of 7 days. Ileal digesta were collected for a total of 24 h during day 6 and 8. Splitting the total range of 90 to 415 g/kg CP into smaller ranges, i.e. from 90 to 220, 220 to 350 or 285 to 415 g/kg CP, provides estimates for CP and AA recoveries which are not significantly different from zero. As a result, dietary CP and AA originating from casein are completely digested and absorbed until the end of the small intestine. In addition, the use of large ranges of dietary CP levels showed that IAAL_B were affected (p < 0.050) by the dietary CP content. Accepting that ileal recoveries of CP and AA are exclusively of endogenous origin when purified corn starch casein‐based diets are fed, IAAL_B were estimated as a function of the dietary CP level. There were linear increases (p < 0.050) in IAAL_B when the dietary CP content was increased from 90 to 415 g/kg. Average IAAL_B expressed in g/kg dry matter intake (DMI) were 16.3, 0.7, 0.2, 0.9 and 0.2 for CP, lysine, methionine, threonine and tryptophan respectively. These values are in close agreement with IAAL_B obtained in grower‐finisher pigs.     

Nutritional strategies to cope with reduced litter weight gain and total tract digestibility in lactating sows

Twelve lactating sows were used to evaluate the effects of reducing dietary crude protein (CP) (14% vs. 12%) and increasing neutral detergent fibre (NDF) levels (18% vs. 22%) on litter performance, total tract apparent digestibility and manure composition in a 4 × 4 latin square arrangement during a 36‐day lactation period. Diets were isoenergetic (2.9 Mcal ME/kg) and had similar total lysine content (0.9%). In addition, a second aim was to compare a reference external marker method (Cr₂O₃) with an internal feed marker [acid‐insoluble ash (AIA)] for the calculation of apparent total tract digestibility of nutrients in lactating sows. The reduction of dietary CP level in lactating sows had no effect on either live‐weight or backfat thickness or apparent total tract digestibility of nutrients. However, the piglets' average daily gain (ADG) was reduced in low dietary CP diets, which suggests that sows reduced milk production due to an underestimation of certain essential amino acid requirements (e.g. valine). The increase of dietary NDF level did not affect sow and litter performance. Nevertheless, the total tract apparent digestibility of organic matter, CP and carbohydrates was reduced, and ether extract digestion was increased in high NDF compared to normal NDF diets equally balanced for ME and lysine content. The coefficients of total tract apparent digestibility of nutrients in lactating sows were greater when using AIA compared to Cr₂O₃ marker, regardless of dietary CP or NDF level, but their coefficients of variation were lower in the former than in the latter. In lactating sows, a trade‐off between litter performance and nutrient digestion is established when reducing dietary CP or increasing NDF levels while maintaining similar lysine content through synthetic amino acids and balancing metabolizable energy through dietary fat sources.     

日粮中添加柠檬酸对肉鸡生产性能的影响

将36只21日龄的艾维茵仔鸡,随机分成6组(第一组为对照组),试验采用玉米-豆饼型基础日粮,各组日粮柠檬酸添加水平分别是0、0.15%、0.25%、0.5%、1%、2%,试验期5周,研究了日粮柠檬酸水平对肉仔鸡生产性能的影响.结果表明,日粮中添加0.25%的柠檬酸,鸡增重最快;添加2%柠檬酸,可显著降低肉鸡增重;添加0.15%、0.25%柠檬酸.鸡的饲料报酬最高.添加柠檬酸对日粮有机物质的消化率有显著影响,其中添加0.25%柠檬酸鸡的蛋白质消化率最高.因此认为,日粮添加0.25%柠檬酸为适宜添加量,添加2%柠檬酸为其最大耐受量.