Evaluation of ground grain versus pre- and post-pellet whole grain additions to poultry diets via a response surface design

1. The objective of this study was to compare the effects of pre- and post-pellet whole grain wheat additions to diets on growth performance, gizzard and pancreas development, nutrient utilisation and starch and protein (N) digestibility coefficients in broiler chickens via an equilateral triangle response surface design.

2. The three apical treatments of the equilateral triangle comprised (1A) a standard diet containing 600 g/kg ground wheat, (2B) the same diet containing 600 g/kg pre-pellet whole wheat and (3C) the same diet containing 300 g/kg ground wheat and 300 g/kg post-pellet whole wheat. Seven blends of the three apical diets were located within the triangle to complete the design and a total of 360 male Ross 308 chicks were offered the ten experimental diets from 7 to 28 d post-hatch. Model prediction and response surface plots were generated with R 3.0.3 software.

3. The most efficient FCR of 1.466 was observed in birds offered an almost equal mixture of the pre- and post-pellet whole grain apical dietary treatments, which corresponded to 172 g/kg ground grain, 256 g/kg pre-pellet whole grain, 172 g/kg post-pellet whole grain in a diet containing 600 g/kg wheat.

4. The most efficient energy utilisation (ME:GE ratio of 0.766) was observed in birds offered a blend of the ground grain and pre-pellet whole grain apical dietary treatments which corresponded to a mixture of 384 g/kg pre-pellet whole grain and 216 g/kg ground grain.

5. Pre-pellet whole grain feeding generated the most pronounced responses in increased relative gizzard contents, reduced gizzard pH and increased relative pancreas weights. Consideration is given to the likely differences between pre- and post-pellet whole grain feeding.     

Ileal amino-acid digestibility of wheat, autoclaved wheat and spaghetti by-products for broiler chicks

An experiment was conducted to determine true and apparent ileal amino‐acid digestibility of a native cultivar of wheat (Mahdavi), autoclaved wheat (120°C for 30 min) and spaghetti by‐products available in Iran. One hundred 21‐day‐old broiler chickens were fed a standard corn–soybean meal starter diet from day 0 to 28 post hatch. At 28 days 80 chicks were distributed according to possessing very nearly the same average bodyweight to 20 wire cages. The experimental units were allocated at random to five dietary treatments with four replicates per treatment. The basal diet contained corn and soybean meal as the major ingredients. Three test diets were formulated containing wheat, autoclaved wheat and spaghetti by‐products as the sole source of dietary protein and each test diet was combined with a basal diet 50:50 on a weight basis to form three assay diets. The apparent and true digestibility of amino acid in the test ingredients were estimated from those in the assay diets basal/test diet mixtures, using the difference method. The apparent and true amino‐acid digestibility of the test ingredients were significantly different (P < 0.01). Autoclaving of wheat increase its amino‐acid digestibility (P < 0.01). Among the test ingredients, the average ileal amino‐acid digestibility of spaghetti by‐products was higher than wheat and autoclaved wheat but it was lower than values for the basal diet (P < 0.01).     

西北地区和尚头小麦遗传多样性及农艺性状的关联分析

为了解西北地区和尚头小麦种质资源的遗传特性及主要农艺性状特征,采用43份不同来源的和尚头小麦种质材料,在均匀分布于小麦21条染色体上的150个SSR(simple sequence repeats)位点上检测遗传多样性,同时对19个农艺性状在两个试验点进行表型鉴定,并采用GLM(general linear model)模型进行分子标记与表型性状的关联分析。结果表明,19个农艺性状中数量性状遗传多样性明显高于质量性状,除壳色外,其他性状之间均存在不同程度的相关性。利用45对具有多态性的SSR标记共检测出151个等位变异,各标记等位位点变化范围为2～6,平均为3.36个,PIC(polymorphism information content)值变异范围为0.044～0.771。群体遗传结构分析将43份材料划分为8个亚群。关联分析发现11个SSR标记与农艺性状显著关联,单个标记对表型变异的解释率为8.89%～24.74%,这些标记可为特色小麦分子标记辅助选择育种提供理论参考。     

Model averaging for genome‐enabled prediction with reproducing kernel Hilbert spaces: a case study with pig litter size and wheat yield

Predictive ability of yet‐to‐be observed litter size (pig) grain yield (wheat) records of several reproducing kernel Hilbert spaces (RKHS) regression models combining different number of Gaussian or t kernels was evaluated. Predictive performance was assessed as the average (over 50 replicates) predictive correlation in the testing set. Predictions from these models were combined using three different types of model averaging: (i) mean of predicted phenotypes obtained in each model, (ii) weighted average using mean squared error as weight or (iii) using the marginal likelihood as weight. (ii) and (iii) were obtained in a validation set with 5% of the data. Phenotypes consisted of 2598, 1604 and 1879 average litter size records from three commercial pig lines and wheat grain yield of 599 lines evaluated in four macro‐environments. SNPs from the PorcineSNP60 BeadChip and 1447 DArT markers were used as predictors for the pig and wheat data analyses, respectively. Gaussian and univariate t kernels led to same predictive performance. Multikernel RKHS regression models overcame shortcomings of single kernel models (increasing the predictive correlation of RKHS models by 0.05 where 3 Gaussian or t kernels were fitted in the RKHS models simultaneously). None of the proposed averaging strategies improved the predictive correlations attained with single models using multiple kernel fitting.     

景泰绿洲3种小谷物的产草量与牧草营养成分预测

为了预测景泰绿洲春小麦(Triticum aestivum)、燕麦(Avena sativa)、黑麦(Secale cereale)的产草量和营养品质,通过田间试验,测得牧产草量、株高和分蘖,室内测定粗蛋白、粗脂肪、中性洗涤纤维、酸性洗涤纤维、粗灰分和可溶性碳水化合物,分析各指标之间的相关性。结果表明,收获干草的3种小谷物分蘖和株高均与可溶性碳水化合物之外其它5个营养指标存在显著相关性(P0.05),模拟轮牧的春小麦和黑麦株高与营养指标均无相关性(P0.05),燕麦和黑麦的分蘖与6个营养指标均呈显著相关(P0.05)。建立了根据株高预测产草量和营养品质的模型、用分蘖预测牧草营养品质的模型、用产草量预测牧草营养品质的模型、用分蘖和产草量两个因子综合预测营养品质的模型。经过与实测值对比,各预测模型的准确性均较高。     

旱地栽培小麦及秸秆青贮饲料的发酵特性、营养成分及体外瘤胃降解特性

本研究总结了全珠小麦青贮饲料和小麦秸秆青贮饲料的保存和营养特性。选择25包来自4个不同田间的全珠小麦青贮饲料和10包小麦秸秆青贮饲料,分别进行了全株小麦青贮和秸秆青贮试验。全珠小麦青贮饲料保存良好,平均pH值为4.46,乳酸、乙酸和丁酸盐的浓度分别为19.2、10.4和4.7g/kg。小麦秸秆青贮饲料的平均pH值为5.46,由于干物质含量较高,发酵受到抑制,乳酸、乙酸和丁酸盐的浓度分别1.9、2.2和1.0g/kg。全株小麦青贮饲料粗蛋白含量为78g/kg,中性洗涤纤维含量为546g/kg,非纤维碳水化合物含量为306g/kg。全珠小麦青贮饲料中粗蛋白和非纤维碳水化合物含量变化较大,中性洗涤纤维含量变化相对较小,这与籽粒成熟度的差异有关。全株小麦青贮饲料和秸秆青贮饲料的体外有机质降解率分别为56.1%和29.3%。全株小麦青贮饲料的体外有机质降解与pH、乳酸和乙酸盐含量无显著相关性(P>0.05),与丁酸盐含量和氨氮比值有显著相关性的趋势(P=0.07)。瘤胃对全珠小麦青贮饲料的发酵早期体外气体生成的变异系数越高,相对于一些纤维组分,如中性洗涤纤维和酸性洗涤纤维,测定的非纤维碳水化合物变异系数也相应升高。综上所述,冬季旱地栽培的小麦可以作为全株青贮饲料在瘤胃中发酵提供能量,小麦秸秆也可以作为纤维原料进行青贮。     

组合型木聚糖酶对21日龄黄羽肉鸡器官指数、内源消化酶活性以及肠道吸收功能的影响

通过对21日龄黄羽肉鸡器官指数和胃蛋白酶、胰蛋白酶、胰脂肪酶、胰淀粉酶以及血清中木糖水平进行检测,研究酶制剂对动物内脏器官所产生的影响,以及组合酶和单酶之间的差异。木聚糖酶在小麦型日粮中添加,降低了肝脏、肌胃、腺胃、十二指肠、空肠和回肠的器官指数,增加了胰腺的器官指数;降低了胃蛋白酶和胰蛋白酶的分泌水平;组合酶比单酶降低小肠器官指数更明显,单酶增加了胰脂肪酶的分泌水平,组合酶降低了胰脂肪酶的分泌水平,差异不显著(P>0.05)。小麦型日粮饲喂组血清中木糖的水平高于玉米型日粮组和加酶组,酶制剂的添加降低了血液中的木糖水平,各处理组之间差异不显著(P>0.05)。     

再论生长的冗余

生长冗余概念是由盛承发在１９９０年首先提出来的。本文从作物个体与群体对立统一关角度出发提出了作物生长冗余的一个解释。盛承发提出的随机波动环境假说可以导致生长冗余的产生；但是，他从物种利益角度出发解释生物进化还有待商榷。本文还综述了黄土高原阗干旱雨养农业地区小麦根系生长冗余问题，并根据前入工作提出适度增加播种深度和苗期叶片刈割等高产栽培措施。     

甘肃陇南冬小麦条锈病气象等级预测模型的建立与应用

甘肃陇南地区是中国小麦（Triticum aestivum）条锈病菌核心越夏区,其越夏菌量对中国中东部来年春季小麦条锈病发生发展程度影响很大。本研究利用陇南冬麦区14个代表站点1990-2007年的气象资料和条锈病资料,依病田率将气象条件划分为5个等级,采用逐步回归方法建立了小麦条锈病气象等级预测模型。经历史回代检验,预测模型误差达2个等级的占12%,完全准确的为25%;对于实际病害等级为1~2级的气象等级拟合误差达2个等级的为23%,其他都在1个等级之内,预测效果良好。     

Feeding value of enset (Ensete ventricosum), Desmodium intortum hay and untreated or urea and calcium oxide treated wheat straw for sheep

Feed intake, in vivo nutrient digestibility and nitrogen utilization were evaluated in male sheep fed different fractions (leaf, pseudostem, corm, whole plant) of enset, untreated or 2% urea‐ and 3% calcium oxide‐ (CaO or lime) treated wheat straw and Desmodium intortum hay as sole diets. All feeds, except D. intortum hay and enset leaf had low crude protein (CP) content. Non‐fiber carbohydrate contents were higher in enset fractions, especially in pseudostem and corm relative to other feeds. Enset leaf and pseudostem had high calcium, phosphorus and manganese contents. Corm, whole enset and D. intortum hay were rich sources of zinc. Daily dry matter and CP intakes were higher (p < 0.05) in sheep fed D. intortum hay (830 and 133 g, respectively) than those fed pseudostem (92 and 7.8 g, respectively). Organic matter digestibilities were highest for corm (0.780) and whole enset (0.776) and lowest for D. intortum hay (0.534) and untreated wheat straw (0.522). The CP digestibility ranged from 0.636 in D. intortum hay to 0.408 in corm. Nitrogen (N) balance was highest (p < 0.05) in D. intortum hay (10.4 g/day) and lowest in corm (?1.3 g/day). Enset leaf could be a useful protein supplement whereas the pseudostem and corm could be good sources of energy.