Genotype X environment interaction in two breeds of chickens kept under two management systems in Southern Ethiopia

Rhode Island Red (RIR) and Fayoumi chickens were evaluated on-station in a college farm and on-farm in village farms, whereas local chickens were only tested under on-farm condition. Traits recorded are egg production and egg quality, body weight and feed efficiency at 4, 8 and 12 months of age. Significant age effect was found for most traits except for shell thickness, albumen height and egg length. Also, significant breed by management system interactions were found for all traits measured in both systems. Fayoumi chickens were higher in egg production in both management systems. Moreover, they were higher than RIR in feed efficiency. RIR were higher in most egg quality traits and had higher weight gain. Local chickens performed below the two exotic breeds in most of the traits, but had higher weight gain than Fayoumi. Chickens kept on-farm had poorer performance than those kept on-station in all traits except for yolk colour.     

Evaluation of amino-acid supplemented diets varying in protein levels for laying hens

The ideal amino acid concept is increasing by being applied to laying hens. However, understanding the responses of modern laying hens to decreasing levels of dietary protein balanced with crystalline amino acids has yet to be examined. In this study, 5 dietary treatments varying in CP content (18.0, 17.5, 17.0, 16.5, and 16.0%) were formulated at a fixed dietary energy concentration of 2,825 kcal of ME/kg of feed. The crystalline amino acids, including Met, Thr, Ile, Val, Trp, and Lys, were supplemented according to an assumed ideal AA profile, and all diets contained 0.831% ileal digestible Lys. Irrespective of the CP levels, the ratio of Lys and the profile of different essential amino acids in relation to Lys remained similar in all the diets. A total of 540 21-week-old Hy-Line W36 hens were used with 6 replicates per treatment group. This trial was conducted for a period of 14 wk, ranging from wk 21 to 34. Egg production, daily egg mass, feed intake, and FCR were not affected in the low-protein groups. Egg weight and N excretion declined, whereas egg yolk color increased in the low-protein groups. Decreasing dietary CP was found to have no effect on blood ammonia and plasma uric acid. The application of the assumed ideal AA profile can lead to reduced dietary protein level, from 18 to 16%, without affecting the production performance of laying hens during 21 to 34 wk of age. The ratios of standardized ileal digestible Met, Met + Cys, Thr, Trp, Arg, Ile, and Val to standardized ileal digestible Lys were 50, 91, 70, 21, 104, 80, and 88%, respectively, in the assumed ideal AA profile. Excretion of nitrogen was significantly decreased from hens fed the protein-reduced diet without impairing BW.     

皖西白鹅3种常用蛋白饲料原料的氨基酸标准回肠消化率测定

为研究皖西白鹅对常用蛋白饲料原料豆粕、菜籽粕及DDGS的氨基酸标准回肠消化率（SIAAD）,选取体重相近的56日龄皖西白鹅288只,随机分为24个饲喂栏,每个饲喂栏12只（公、母各半）,试验期为35 d,0~28 d为预饲期,全部饲喂相同基础日粮;29~35 d为试验期,分别饲喂待测饲粮和无氮饲粮6 d,每种饲粮6个饲喂栏（重复）,第35天早上饲喂前采集回肠食糜并测定食糜中的氨基酸含量。结果显示：豆粕、菜籽粕和DDGS的平均SIAAD分别为88.30%、81.17%、88.99%,且豆粕和DDGS平均SIAAD显著（P<0.05）高于菜籽粕。豆粕中氨基酸的SIAAD如下：赖氨酸（Lys）81.27%、蛋氨酸（Met）95.14%、苏氨酸（Thr）85.08%、缬氨酸（Val）88.25%、亮氨酸（Leu）88.20%、异亮氨酸（Ile）87.33%、苯丙氨酸（Phe）91.66%、组氨酸（His）87.77%和精氨酸（Arg）92.18%;菜籽粕氨基酸的SIAAD如下：Lys 75.19%、Met 87.87%、Thr 82.96%、Val 84.25%、Leu 83.19%、Ile 81.94%、Phe 86.08%、His 84.39%和Arg 83.10%;DDGS 中氨基酸的SIAAD如下：Lys 83.74%、Met 94.59%、Thr 90.85%、Val 91.97%、Leu 93.67%、Ile 91.38%、Phe 94.73%、His 90.59%和Arg 94.09%。该试验结果为豆粕、菜籽粕和DDGS在皖西白鹅饲粮上的高效利用和合理配制低氮饲粮提供数据参考。     

Comparative effects of individual amino acid excesses when added to a corn-soybean meal diet: effects on growth and dietary choice in the chick

Six experiments were conducted with 8-d-old crossbred chicks to evaluate the effects of 4% excesses of DL-methionine (Met), L-phenylalanine (Phe), L-tryptophan (Trp), L-lysine (Lys), L-histidine (His), L-threonine (Thr), L-isoleucine (Ile), L-arginine (Arg), L-valine (Val) or L-leucine (Leu) on growth or dietary "choice" (i.e., self-selection) when added to 23% protein corn-soybean meal (C-SBM) diets. Arginine and His were supplied as the free base and Lys as Lys X acetate to avoid acid-base problems. In the growth studies, weight gain was reduced 92, 79, 53, 50, 47, 31, 29, 15, 9, 4 and 0% by additions of 4% Met, Phe, Trp, His, Lys, Tyr, Thr, Ile, Arg, Val and Leu, respectively. Improvements (P less than .05) in weight gain, feed intake and gain/feed occurred by addition of 1% Arg to the C-SBM diet supplemented with 4% excess Phe or Tyr. Addition of 1% Arg to the C-SBM diet supplemented with 4% excesses of most of the other amino acids also tended to improve performance, although diets imbalanced with Lys, Val or Leu did not respond to supplemental Arg. Self-selection studies revealed that chicks preferred the C-SBM diet containing 4% excess Lys over diets containing 4% excesses of Met, Thr, Arg or Trp. Moreover, chicks preferred diets with 4% excess Met, Thr or Arg over those containing an equal excess of Trp. When given a choice between the C-SBM diet and this diet supplemented with 4% Leu, chicks consumed similar quantities of both diets.     

奶牛小肠蛋白质体系的局限性与氨基酸平衡

现在国内外已将奶牛的可消化粗蛋白体系改进为小肠可消化蛋白质体系,但由于小肠蛋白质的氨基酸组成变异性很大,其CV高达5.6%~19.2%,因而导致可代谢蛋白质的转化效率不稳定,表观效率便会掩盖实际需要。奶牛的第一和第二限制性氨基酸分别为赖氨酸和蛋氨酸,较多研究认为组氨酸为第三限制性氨基酸,但当肝后部提供的组氨酸不能满足产奶需要时,组氨酸可来自体储存的分解,因此尚不能完全确定。据对87个试验结果的统计分析表明,在瘤胃后供给额外的赖氨酸和蛋氨酸,则奶牛的产奶量、乳蛋白量、乳蛋白率均明显增加;对48个试验结果的统计分析结果表明,在可代谢蛋白质被满足供应的基础上,当赖氨酸和蛋氨酸分别达到7.08%和2.35%时,乳蛋白质产量达到最高点。法国INRA在其试验的基础上,确定小肠可消化真蛋白质中的赖氨酸和蛋氨酸的适宜含量为7.3%和2.5%,由于我国现行的是小肠可消化粗蛋白质体系,故建议其赖氨酸和蛋氨酸的含量为6.0%和1.9%,但须评定瘤胃微生物蛋白质和饲料非降解蛋白质的赖氨酸和蛋氨酸含量,并调整日粮使其达到平衡。     

0～3周龄北京鸭氨基酸理想模式的研究

依据扣除法原理，根据现有氨基酸需要量标准和目前的研究结果规划出一种氨基酸模式，依次将模式中赖氨酸、蛋氨酸、色氨酸、苏氨酸、异亮氨酸扣除20％，而非扣除的氨基酸量保持不变，来确定扣除某一种氨基酸后对育雏期北京鸭生产性能和血液生化指标的影响，确定出理想的氨基酸比例。试验共设6个处理组，为6种氨基酸模式，每个处理设4个重复。结果表明：北京鸭育雏期氨基酸理想模式为赖氨酸：蛋氨酸：色氨酸：苏氨酸：异亮氨酸=100：42：22：38：48。     

Lipid profile in eggs of Araucana hens compared with Lohmann Selected Leghorn and ISA Brown hens given diets with different fat sources

1. In a cross-over trial, the egg cholesterol and fatty acid composition of Araucana hens was compared with those of two commercial breeds (Lohmann Selected Leghorn and ISA Brown) under two feeding regimes, either high (Hn-3) or low (Ln-3) in long-chain n-3 fatty acids. 2. The Hn-3 diet was formed by isocaloric substitution of animal fat in the control diet (Ln-3) by a dry product containing stabilised fish oil with standardised concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 3. Both breed and diet had influences on egg composition, without interactions. 4. The Araucana breed showed lower feed intake and lower egg weights than the other two breeds. The yolk weight was similar, leading to a much higher yolk:albumen ratio in the Araucana eggs. 5. In comparison to commercial breeds, Araucanas produced eggs with higher cholesterol content per g of yolk, which was even more pronounced when expressed per g of egg, due to the high yolk content of the eggs. The cholesterol content of an egg remained unchanged by the diet, irrespective of the dietary fat source. 6. Changing to the Hn-3 diet led to greater concentrations of polyunsaturated fatty acids (PUFA) and lower concentrations of monounsaturated fatty acids (MUFA) contents in the yolk, without a change in the ratio of saturated (SFA) to unsaturated fatty acids (UFA). 7. Within the PUFA, the n-3 fatty acids increased at the expense of the n-6 fatty acids, indicating a competition between n-3 and n-6 fatty acids for incorporation in the yolk.     

Effect of dietary excess of branched‐chain amino acids on performance and serum concentrations of amino acids in growing pigs

Depressed performance and availability of some amino acids (AA) in pigs fed excess Leu diets appear to be related to lower feed intake. Surplus Ile and Val may help to overcome this effect. An experiment was conducted with 24 pigs (31.8 ± 1.2 kg initial BW) to evaluate the effect of dietary excess of either Leu alone or with surplus Ile and Val on performance and serum concentration (SC) of essential AA. Treatments were as follows: T1, basal diet; T2, basal plus 0.43% L‐Leu (excess Leu); T3, basal added with 0.43% L‐Leu, plus 0.20% L‐Ile and 0.25% L‐Val (excess LIV). The basal diet was formulated to contain 0.90% standardized ileal digestible Lys and added with crystalline L‐Lys, L‐Thr, DL‐Met, L‐Trp, L‐Leu, L‐Ile, L‐His and L‐Val to create essential AA:Lys ratios close to an ideal protein for growing pigs. All pigs were fed the same amount of feed twice a day (average, 3.42× the requirement of NEm). Blood samples were collected at 2.5 (absorptive) and 11.0 h (post‐absorptive) post‐prandial to analyse SC of AA. Excess of either Leu or LIV did not affect growth rate nor feed conversion. Excess Leu increased Leu SC and decreased Ile and Val SC (p < 0.05) at both absorptive and post‐absorptive phases, but excess LIV restored the SC of Ile and Val. The SC of other essential AA was not affected by excess of either Leu or LIV. The SC of all AA during absorptive, on average, was about two times higher than that of post‐absorptive phase. These results suggest that the reduced availability (SC) of Ile and Val in pigs consuming excess Leu diets is attributed to a reduced absorption and increased cellular degradation rates of them.     

长期添加藤茶提取物对肥育猪血清游离氨基酸、胴体性状和肉品质的影响

本试验旨在研究日粮中长期添加藤茶提取物对肥育猪血清游离氨基酸、胴体性状和肉品质的影响。选用平均初始体重为30 kg的三元杂交（杜×长×大）去势公猪90头,随机分成3个处理组,分别为对照组（CON组,饲喂基础日粮）、植物精油复合物组（A组,基础日粮中添加0.03%植物精油复合物）、藤茶提取物组（B组,基础日粮中添加0.03%藤茶提取物）,每组6个栏,每栏5头猪。试验猪体重达到130 kg左右出栏称重,每栏挑选最接近该栏平均体重的猪进行采血、屠宰,以A组为阳性对照。结果表明：①与CON组比较,B组的血清游离氨基酸中必需氨基酸赖氨酸（Lys）、蛋氨酸（Met）、异亮氨酸（Ile）等的含量显著升高（P<0.05）,组氨酸（His）的含量显著降低（P<0.05）,非必需氨基酸谷氨酸（Glu）、丙氨酸（Ala）、脯氨酸（Pro）等的含量显著降低（P<0.05）;与A组比较,B组的血清游离氨基酸中必需氨基酸Met、苏氨酸（Thr）含量显著升高（P<0.05）,His含量显著降低（P<0.05）,非必需氨基酸均不存在显著差异（P>0.05）。②与CON组比较,A、B组猪的腹脂重均显著提高（P<0.05）,但A、B组之间腹脂重不存在显著差异（P>0.05）;宰前重、胴体重、屠宰率、背膘厚、眼肌面积等3组间均无显著差异（P>0.05）。③宰后背最长肌肉色、pH、滴水损失、大理石评分、肌内脂肪和剪切力3组间均无显著差异（P>0.05）;与CON组比较,B组肌肉嫩度评分显著提高（P<0.05）,A、B组的肉汤清浊度评分均显著降低（P<0.05）,而肌肉外形、气味、异味、多汁性、肉汤鲜度评分在3组间无显著差异（P>0.05）;3组的肌纤维直径和密度均无显著差异（P>0.05）。综上,日粮中长期添加0.03%藤茶提取物可以显著改变肥育猪血清游离氨基酸组成,并一定程度改善猪肉嫩度;长期添加藤茶提取物或植物精油复合物对肥育猪胴体和肌肉性状均无显著改善效果,且均易造成腹部脂肪沉积。     

断奶仔猪血清氨基酸含量和生化参数对不同蛋白质水平饲粮的动态响应

本文旨在研究断奶仔猪血清氨基酸含量和生化参数对不同蛋白质水平饲粮的动态响应。选取18头35日龄平均体重为(10.0±1.0)kg三元(杜×长×大)杂交断奶阉公猪,随机分为3组(每组6个重复,每个重复1头猪),并分别饲喂蛋白质水平为14%(LP)、17%(M P)和20%(HP)的饲粮。每头试验猪安装颈动脉血管插管,术后恢复5 d,于第6~8天正式试验。每天采食前,采食后30、60、120、180和300 min连续采集颈动脉血液10 m L,分别检测血清游离氨基酸含量和相关生化指标。结果表明:不同蛋白质水平饲粮对仔猪采食前后各时间点血清中游离赖氨酸(Lys)、蛋氨酸(Met)、苏氨酸(Thr)、色氨酸(Trp)、天冬氨酸(Asp)、丝氨酸(Ser)、甘氨酸(Gly)和谷氨酸(Glu)含量影响均不显著(P0.05)。但血清中Lys、Met、Thr、Trp含量随饲粮蛋白质水平的降低而升高。HP组仔猪采食前后各时间点血清游离氨基酸[缬氨酸(Val)、异亮氨酸(Ile)、精氨酸(Arg)]和尿素含量显著高于MP和LP组(P0.05)。采食后120~300 min HP组血清Leu含量显著高于LP组(P0.05)。采食后各时间点LP组血清总蛋白(TP)、白蛋白(ALB)含量及碱性磷酸酶(ALP)活性显著高于HP和MP组(P0.05)。各组仔猪采食后血清游离氨基酸含量和相关生化指标随时间变化无显著差异(P0.05)。综上所述,断奶仔猪饲粮在平衡4种氨基酸(Lys、Met、Thr、Trp)的基础上,常规饲粮蛋白质水平降低3个百分点,血清游离Val、Ile、Arg含量显著降低,但对血清中其他氨基酸和相关生化指标无显著影响;而蛋白质水平降低6个百分点,血清游离Leu和尿素含量显著降低,TP、ALB含量和ALP活性显著升高,但对血清中其他氨基酸和相关生化指标的影响不显著。     

不同精粗饲料对泌乳中期山羊氨基酸的代谢流向及乳蛋白含量的影响

 通过检测泌乳中期山羊血浆及乳中游离氨基酸含量的变化,探讨不同精粗比饲料对机体中氨基酸（ａｍｉｎｏａｃｉｄｓ,ＡＡ）的代谢流向及乳蛋白的影响。选用泌乳中期山羊７只,随机分为２组,分别饲喂精粗比４∶６（低精料组）和６∶４（高精料组）日粮,颈静脉血管瘘采血,手工挤奶取奶样。Ｂｒａｄｆｏｒｄ法测定乳中总蛋白质浓度,ＲＰ－ＨＰＬＣ检测山羊血浆和乳中游离氨基酸的含量。结果表明,２组山羊血浆中均分离出１４种游离氨基酸,乳中分离出８种游离氨基酸,不同精粗比饲料对血液或乳中游离氨基酸谱无明显影响。不同精粗比日粮情况下,除丙氨酸外,血液中游离氨基酸的含量均高于乳中同种氨基酸的含量;且血液中生酮氨基酸（Ｌｅｕ,Ｌｙｓ）、兼性氨基酸（Ｐｈｅ,Ｉｌｅ）和支链氨基酸（Ｌｅｕ,Ｉｌｅ和Ｖａｌ）含量显著或极显著高于乳中。高精料组除Ｇｌｙ和Ａｌａ外,其余氨基酸含量均低于低精料组;乳中总蛋白浓度略高于低精料组,但无统计学差异。表明血液中游离氨基酸为乳蛋白的合成提供了原料和能量保证。饲喂高精料日粮,血液中游离氨基酸含量较低,不利于乳蛋白含量和产量的提高。     

西藏地区改良黄牛和本地黄牛血液代谢指标和肉品质的差异比较

试验的目的是比较高海拔地区改良黄牛与本地黄牛血液生化指标和肉品质的差异。从血液中氨基酸的含量来看．本地黄牛蛋氨酸、异亮氨酸、酪氨酸、苯丙氨酸和赖氨酸5种氨基酸的含量均显著高于改良黄牛（P〈0．05）；色氨酸、天冬氨酸、丝氨酸、甘氨酸、丙氨酸、半胱氨酸、缬氨酸、亮氨酸、组氨酸和精氨酸10种氨基酸的含量，本地黄牛均高于改良黄牛，但差异不显著（P〉0．05）；苏氨酸、谷氨酸和脯氨酸3种氨基酸的含量，本地黄牛均低于改良黄牛的含量，但差异不显著（P〉0．05）；本地黄牛的总氨基酸、必需氨基酸、非必需氨基酸和鲜味氨基酸的含量均高于改良黄牛（P〉0．05）。从血液生理生化指标上来看，总胆固醇、尿素氮、总抗氧化能力3项指标，本地黄牛显著大于改良黄牛（P〈0．05）；低密度脂蛋白胆固醇的指标含量，本地黄牛高于改良黄牛，且极显著（P〈0．01）；补体第四成分、甘油三酯、葡萄糖、IgA、IgG、IgM、丙二醛、过氧化氢酶、脂蛋白胆固醇9项指标．本地黄牛均高于改良黄牛，但不显著（P〉0．05）；极低密度脂蛋白、C3、总蛋白、超氧化物歧化酶4项指标，本地黄牛均低于改良黄牛．但差异不显著（P〉0．05）。从肉品质上来看，改良黄牛和本地黄牛的大理石纹评分、眼肌面积、剪切力、蒸煮损失等指标均无显著差异（p〉0．05）。     

虫草粉联合酵母硒对蛋鸡产蛋高峰中期产蛋性能、蛋品质、抗氧化性和免疫功能的影响

为了研究虫草粉（古尼虫草地顶孢霉培养物）联合酵母硒对蛋鸡产蛋性能、蛋品质、抗氧化功能和免疫功能的影响,试验选用450羽24周龄海兰褐壳蛋鸡,随机分为5组,每组6个重复,每个重复15羽。对照组饲喂基础饲粮,试验Ⅰ~Ⅳ组饲喂添加0.1 mg/kg酵母硒联合不同剂量虫草粉（0、0.2%、0.3%和0.4%）的基础饲粮,试验期27周;选取产蛋高峰中期（第40周龄）蛋鸡进行产蛋性能、鸡蛋品质、免疫功能和抗氧化功能分析。结果显示,与对照组相比,产蛋高峰中期试验Ⅲ组蛋鸡的产蛋率、平均蛋重均显著提高,料蛋比显著降低（P<0.05）;鸡蛋哈夫单位、蛋壳颜色、蛋壳强度、蛋黄颜色、蛋清粗蛋白质含量、蛋黄粗蛋白质和粗脂肪含量均显著升高（P<0.05）,蛋清中必需氨基酸Leu、Lys、Met、Trp、Phe、Thr、Val和His及非必需氨基酸Ala、Asp、Glu、Pro和Tyr水平也显著增加（P<0.05）;试验Ⅳ组蛋鸡的蛋壳颜色、蛋壳强度、哈夫单位和蛋清粗蛋白质含量均显著提高（P<0.05）,蛋清中必需氨基酸Ile、Gly、Arg和非必需氨基酸Cys、Ser水平均显著增加（P<0.05）;试验Ⅰ~Ⅳ组蛋鸡蛋黄、蛋清中硒含量均显著增加（P<0.05）。同时,与对照组相比,产蛋高峰中期试验Ⅲ组蛋鸡血清MDA含量显著下降（P<0.05）,WBC数量、血清IFN-γ和IL-2水平及T-AOC和T-SOD活性均显著升高（P<0.05）。结果表明,饲粮中联合添加酵母硒和适量的虫草粉能明显提高产蛋高峰中期蛋鸡的产蛋性能和鸡蛋品质,增强机体免疫力和抗氧化能力,以0.1 mg/kg酵母硒联合添加0.3%虫草粉的效果最佳。     

添加剂对紫花苜蓿青贮品质及小肠可吸收氨基酸的影响

为研究添加复合乳酸菌和葡萄籽单宁对紫花苜蓿(Medicago sativa L.)青贮品质及小肠可吸收氨基酸的影响，选用凋萎后二茬现蕾期紫花苜蓿为材料，设置对照(CK)，葡萄籽单宁(G)、复合乳酸菌(戊糖乳杆菌+戊糖片球菌+乳酸片球菌，L)和复合乳酸菌+葡萄籽单宁(LG)组，青贮60 d后测定其品质，并采用体外三步法测定其小肠可吸收氨基酸含量。结果表明：与CK组相比，G和LG组青贮饲料乳酸、乙酸、丁酸、总挥发性脂肪酸和氨态氮含量均显著降低(P<0.05)；L和G组粗蛋白含量显著提高(P<0.05)。与其他三组相比，G组青贮饲料的Ile，Leu，Lys，His，Arg，Tyr和总氨基酸含量显著提高，菌体蛋白以及小肠可吸收Ile，Lys，His，Arg，Ser和总氨基酸含量显著提高(P<0.05)。因此，添加葡萄籽单宁对紫花苜蓿青贮品质有一定改善作用，明显提高青贮饲料中Lys，His和Arg以及总氨基酸的小肠可吸收量。     

Limiting order of amino acids and the effects of phytase on protein quality in corn gluten meal fed to young chicks

An amino acid deletion assay, a protein efficiency ratio (PER) assay, and a slope-ratio growth assay were used to establish the limiting order of AA, and to determine the effects of microbial phytase on protein utilization in corn gluten meal (CGM) fed to chicks during the period of 8 to 21 d posthatching. In Assay 1, a 12% CP CGM diet was fortified with AA to fulfill the digestible AA ideal profile (only Phe + Tyr, Leu, and Pro exceeded requirements) for young chicks. Amino acids were then individually deleted, and all diets were fortified to 23% CP, with Glu varying as necessary. A Met-fortified 23% CP corn-soybean meal diet served as a positive control. No weight gain or feed efficiency differences were observed between the fully fortified CGM basal diet and the corn-soybean meal positive-control diet. The limiting order of AA established in CGM was 1) Lys, 2) Trp, 3) Arg, 4) Thr, 5) Val, 6) Ile, 7) His, 8) cystine, and 9) Met. In Assay 2, diets with 10% CP furnished by CGM or casein were fed in the presence and absence of 1,200 U/kg phytase. A protein source x phytase interaction (P < 0.05) was observed for weight gain, gain:feed, and PER, indicating positive responses to phytase when casein was fed but negative responses to phytase when CGM was fed. In Assay 3, graded levels of protein (8, 16, and 24% CP) furnished by CGM were fed in the presence and absence of 1,200 U/kg phytase. Weight gain and gain:feed increased linearly (P < 0.05) as a function of protein intake, but phytase supplementation had no effect on weight gain or gain:feed slopes. These results indicate that 1,200 U/kg phytase did not increase either CP or AA utilization in CGM for young chicks.     

断奶羔羊4种必需氨基酸限制性顺序和需要量模型探索

本试验旨在采用氨基酸部分扣除法研究断奶羔羊的4种必需氨基酸的限制性顺序和需要模型。选取50日龄断奶湖羊公羊100只随机分为5组,每组4个重复,每个重复5只羊。对照组为氨基酸平衡(PC)组,饲喂氨基酸平衡的开食料,4个试验组开食料在PC组的基础上分别扣除赖氨酸(PD-Lys组)、蛋氨酸(PD-Met组)、苏氨酸(PD-Thr组)和色氨酸(PD-Trp组),其余氨基酸含量保持一致。预试期为10 d,正试期为60 d。于羔羊60、90和120日龄称量体重,在120日龄每组随机选取6只羔羊进行屠宰。结果表明:1)60~120日龄和90~120日龄,PD-M et组羔羊平均日增重(ADG)显著低于其他各组(P0.05),饲料转化率(F/G)显著高于其他各组(P0.05);120日龄时,PD-Met组宰前活重、空体重、胴体重、眼肌面积、头重、蹄重及皮毛重均显著低于PC、PD-Thr和PD-Trp组(P0.05),但是5组间屠宰率(DP)、GR值和血液重差异不显著(P0.05)。2)以最佳ADG和F/G为评价指标时,60~90日龄和90~120日龄氨基酸限制性顺序为Met、Lys、Thr和Trp;而以最佳DP为评价指标时,120日龄氨基酸的限制性顺序为Trp、Thr、Lys、Met。3)以最佳ADG作为评价指标时,60~90日龄和90~120日龄Lys、M et、Thr和Trp的适宜比例分别为100∶44∶44∶8和100∶42∶38∶12;以最佳F/G作为评价指标时,60~90日龄和90~120日龄Lys、M et、Thr和Trp的适宜比例分别为100∶54∶45∶7和100∶47∶39∶12;以最佳DP为评价指标时,60~120日龄Lys、M et、Thr和Trp的适宜比例为100∶34∶38∶8。总之,饲粮必需氨基酸(Lys、Met、Thr和Trp)缺乏严重影响湖羊断奶羔羊的生长性能、屠宰性能和器官指数,特别是Met影响最为明显,其次是Lys,Thr和Trp影响较弱;不同评价指标(ADG、F/G和DP)和不同生长阶段得出的Lys、M et、Thr和Trp的限制性顺序和需要模型是不同的。     

Genetic Relations between Reproduction,Chick Weight and Maternal Egg Composition in a White Leghorn Line

Selection is a viable way to increase egg dry matter, an important trait for the egg processing industry, but simultaneously a change in the embryonic environment takes place. The main purpose of this study was to estimate genetic parameters for the percentage of fertile eggs of eggs set (FERT), percentage of eggs hatched of fertile eggs (HATCH), percentage of live chicks 2 weeks post-hatch of hatched eggs (SURV/h) and of fertile eggs (SURV), and their genetic correlations with egg weight, albumen weight, yolk weight, yolk proportion, albumen dry matter and mean chick weight in a White Leghorn selection line. Direct and maternal heritabilities were low for FERT, HATCH and SURV, and non-existent for SURV/h. All direct-direct genetic correlations between reproduction traits and egg composition traits were not significant. Maternal-direct genetic correlations between HATCH and egg weight, albumen weight, yolk weight, yolk proportion and albumen dry matter were - 0.22, - 0.30, 0.28, 0.52 and 0.26, respectively. Similar correlations were found between SURV and egg composition traits. No significant genetic relationship was found between chick weight and post-hatch survival. In conclusion, within the range of values for egg composition in this study, selection for an increased egg dry matter should not impair reproduction.     

Effects of supplementary iodine on the performance and egg traits of laying hens

1. This experiment was carried out to determine the effects of dietary iodine supplementation on the performance and egg traits of laying hens. A total of 600 SHSY type brown layers aged 21 weeks of age were chosen at random from a large flock. They were randomly distributed into 30 pens at 20 hens per pen. Each treatment comprised 6 replicates of 20 layers in groups of 5 birds. The diets were supplemented with 0, 3, 6, 12 and 24 mg/kg iodine as calcium iodate. The experimental period lasted 30 weeks. 2. There were no significant differences among the groups in body weight, food consumption, egg production, food consumption per kg eggs, eggshell index, eggshell breaking strength, shell thickness or egg yolk index. 3. Supplementation of the diet with 12 mg/kg iodine increased food consumption per dozen eggs compared to the groups fed on diets supplemented with 0 and 6 mg/kg iodine. 4. Egg weight was less in groups fed on diets supplemented with 12 and 24 mg/kg iodine than in the group receiving no iodine supplementation. 5. Iodine supplementation to provide 12 and 24 mg/kg reduced egg albumen index and egg Haugh units. 6. There were no significant differences among the groups in egg cholesterol and egg yolk cholesterol contents. 7. The iodine concentrations in egg yolk, egg albumen and whole egg increased with increased iodine supplementation. 8. As a result, the 3 and 6 mg/kg iodine supplementation of diet could be used to enrich the eggs with iodine without any adverse effect on performance and egg traits.     

Ideal amino acid profile and dietary lysine specification for broiler chickens of 20 to 40 days of age.

1. The aim of the study was to determine the ideal ratio of the essential amino acids lysine (Lys), methionine (Met), threonine (Thr), tryptophan (Trp), arginine (Arg), valine (Val) and isoleucine (Ile) and to assess the required dietary lysine concentration for optimum performance in broiler chickens of 2 commercial strains from 20 to 40 d of age. 2. An identical basal diet was used throughout all experiments. It consisted mainly of maize and soyabean meal and contained 172 g crude protein and 13.2 MJ AME(N) per kg. For each experiment, the basal diet was adequately supplemented with all essential amino acids except the one to be tested, which was supplemented in 6 graded concentrations in exchange for maize starch. One (Met, Trp, Arg, Val, Ile) or 2 (Lys, Thr) growth trials were conducted per amino acid tested and the response in weight gain, food: gain ratio, breast meat yield and abdominal fat were examined. 3. The ideal amino acid ratio relative to Lys (expressed as a percentage) was calculated to be 75% Met+Cys, 63% Thr, 19% Trp, 112% Arg, 71% Ile and 81% Val on a true faecal digestible basis when the data were subjected to broken-line regression analysis. From both lysine studies the concentration for optimum food: gain ratio was calculated, by exponential regression analysis, to be 11.5 g true faecal digestible lys per kg diet.     

低蛋白日粮补充天冬氨酸对断奶至育肥阶段猪生长性能及肉品质性状的影响

旨在研究低蛋白日粮补充天冬氨酸对断奶至育肥阶段猪生长性能、血液生化指标和游离氨基酸、养分表观消化率以及肉品质性状的影响。选取20头45日龄,体重相近（（10.93±0.79） kg）的健康三元杂交（杜×长×大）断奶仔猪,随机分成两组,每组10个重复,每个重复1头猪,仔猪单栏饲养,试验期84 d。对照组饲喂玉米-豆粕型低蛋白基础日粮,试验组饲喂在基础日粮中添加0.5%天冬氨酸的试验饲粮。结果表明：1）添加天冬氨酸可显著提高猪断奶阶段平均日增重（P<0.05）并极显著降低料重比（P<0.01）,但在育肥和生长阶段对生长性能无显著影响（P>0.05）;2）添加天冬氨酸可显著提高断奶阶段血清白蛋白水平和碱性磷酸酶活性（P<0.05）,但对生长和育肥阶段血液生化指标均无显著影响（P>0.05）;3）添加天冬氨酸可显著降低断奶阶段血清中Pro、Met、Thr、Asp、His、Tyr含量（P<0.05）和提高Lys水平（P<0.01）,生长阶段血清中Asp、Lys含量和育肥阶段Asp、Thr含量显著降低（P<0.05）,对其他氨基酸含量无显著影响（P>0.05）;4）天冬氨酸处理可使育肥猪总能、粗蛋白、粗脂肪、粗灰分、粗纤维表观消化率极显著升高（P<0.01）;5）天冬氨酸处理可有效提高熟肉率（P<0.01）和背最长肌中MyHC1的mRNA表达水平（P<0.05）。综上可知,低蛋白日粮全程添加0.5%天冬氨酸可有效提高猪断奶阶段的生长性能,有利于促进其后期肌纤维的发育和改善其肉品质性状。