Assessment of interactions between glutamine and glucose on meat quality,AMPK, and glutamine concentrations in pectoralis major meat of broilers under acute heat stress

The objective of this experiment was to evaluate the effects of dietary glutamine and glucose on pectoralis major meat quality in broilers under acute heat stress. Three hundred 35-day-old male broilers (Arbor Acres) were randomly divided into 5 groups. Broilers in the positive control group were kept in a thermoneutral environment (23 ± 1°C, RH 45%–55%) and fed a basic diet, whereas the experimental (2 × 2) group was exposed to acute heat stress (34 ± 1°C, RH 65%–75%) for 12 h and fed the basic diet that contained glutamine (0 and 10 g/kg) and glucose (0 and 10 g/kg). Compared with the positive control group, acute heat stress without glutamine and glucose supplementation increased (P < 0.05) drip loss, L* values, and AMPK concentrations, but it decreased (P < 0.05) water-holding capacity, moisture, pH, a* values, b* values, and glutamine concentrations in pectoralis major meat of chickens. However, dietary glutamine (10 g/kg) increased (P < 0.05) water-holding capacity, moisture, pH, a* values, b* values, and glutamine concentrations, while it decreased (P < 0.05) drip loss, L* values, and AMPK concentrations in heat-stressed chicken pectoralis major meat. Dietary glucose (10 g/kg) increased (P < 0.05) water-holding capacity, moisture, pH, and a* and b* values, while it decreased (P < 0.05) L* values and AMPK concentrations of pectoralis major meat in chickens exposed to acute high temperature. There were significant interactions between glutamine and glucose in the water-holding capacity, pH values, AMPK, and glutamine levels of pectoralis major meat in the heat-stressed chickens. The above results suggest that the addition of glutamine and glucose in the diet is necessary for broilers during acute heat stress condition.     

黄土高原地形对苜蓿种子产量和质量的影响

对产自甘肃环县黄土高原沟壑区阴坡，阳坡、沟谷阶地和塬地4种地形的苜蓿种子产量和质量进行了研究分析，结果表明，地形对种子产量和质量均有显著影响，其中，阴坡种子产量最低，分别为1．86g/株和311．74kg/hm^2，阳坡单株种子产量最高，为6．41g/株，塬地单位种子产量最高，为650．65kg/hm^2，质量最低种子也产自阴坡，其发芽率只有23％，硬实率却高达66％，地形对种子产量构成因素无显著影响，4种地形的种子产量与其构成因素的相关性完全一致，即除千粒重外，种子产量与其他各因素均存在显著正相关，相关性强弱依次为：单株生殖枝数＞每生殖枝荚果数＞每荚粒数＞千粒重，单株生殖枝数对种子产量贡献最大。     

Performance and Egg Characteristics of Laying Hens Fed Diets Incorporated with Poultry By-Product and Feather Meals

The effects of poultry by-product meal (PBPM) and feather meal (FM) incorporated separately and in combination in the diet on laying hen performance and egg characteristics during postpeak production were determined. Bovans White strain laying hens, 42 wk of age, were fed diets with 0% PBPM and FM, 5% FM, 5% PBPM, or 4% FM + 4% PBPM. Egg production, feed intake, and egg mass were not significantly affected by dietary treatments, whereas egg weight and feed conversion ratio (FCR) were significantly affected. Egg weights of hens receiving 4% FM + 4% PBPM were significantly lower than those fed the control diet, whereas those fed 5% FM or 5% PBPM were intermediate. FCR was significantly improved by the diets containing 5% FM or 5% PBPM compared with the diet containing 4% FM + 4% PBPM. Dietary PBPM decreased Haugh units, but FM did not. Egg breaking strength, shell weight, and weights of albumen and yolk were not affected by treatments. The results suggested that FM or PBPM could be incorporated up to 5% singly or up to 8% in combination in layer diets but with possible detrimental effects on Haugh units, egg weight, and FCR.     

牛冷冻精液质量评估研究进展

人工授精(AI)是第一代动物繁殖生物技术,最近几十年以来,研究人员已经探索出了许多评估冷冻-解冻后精液品质的新技术。由于精子质膜在低渗条件下的功能状态、离子分布及浓度和各种细胞器的功能都与冷冻解冻后精子的存活能力相关,冻精质量的评定也从最初的形态和主观活率分析,发展到更精确的染色质、质膜完整性及分解代谢活性的分子变化分析。但是,在实际应用当中,许多方法花费很大,况且单个的评估参数都与动物精子实际的受精力相关性不强。因此,要提高牛冻精质量的预言强度,应该将这些独立的参数结合起来,利用多元回归分析,建立一套更完美更精确的评估体系。     

西北牧区灌溉人工草地适宜发展规模分析

针对西北牧区水资源和草地资源已被超极限利用的现状,应用水草畜平衡原理,分析了西北牧区灌溉人工草地的发展规模,提出了西北牧区灌溉人工草地适宜发展规模为215.76～239.71万hm^2,载畜量控制在13833.18万羊单位之内即可实现草畜平衡,总体可达到人工种植冷季补饲水平。新增灌溉需水量约为71.85～83.55亿m^3,占2000年灌溉总用水量（777亿m^3）的9.25%～10.75%。解决这一灌溉需水量的可行途径是建设节水型社会,提高水资源利用效率。     

水分胁迫和复水对紫花苜蓿幼苗叶绿素荧光特性的影响

利用PEG-6000模拟水分胁迫(ψs=-0.2MPa,胁迫时间:48 h,复水48 h),研究了紫花苜蓿(Medicago sativa L)品种陇东苜蓿和阿尔冈金叶片叶绿素荧光特性和光合色素含量的变化,旨在探讨紫花苜蓿水分胁迫条件下的光合反应机制.结果表明:光化学淬灭系数(qP)和PSII线性电子传递的有效量子产额(YIELD)以及非光化学淬灭系数(qN)和表观光合电子传递效率(ETR)在胁迫前后随光合有效辐射(PAR)的变化规律分别可用公式:Y=aLn(X) b(Y:qP或YIELD,X:PAR,X≠0)和Y=aX2 bX c(Y:qN或ETR,X:PAR)来表示;在受到干旱胁迫后,PSII最大光能转化效率(Fv/Fm)、PSII潜在活性(Fv/Fo)和光合色素含量均明显低于对照,在任意光强下的qP、YIELD和ETR值也极显著低于对照的相应值,qN值则极显著高于对照的相应值;同时,和对照相比,qN和ETR光响应曲线顶点所对应的光强值在受到胁迫后亦明显下降,表明光抑制初始点的降低和最大光保护能力的减弱,甚至光抑制的提前到来.干旱胁迫使得PSⅡ反应中心结构和功能遭到破坏而部分关闭,光合电子传递受阻,光能利用与光化学转化与能力下降,吸收的光能更多的以热能形式耗散.复水后,虽然有光保护机制的存在,但除陇东苜蓿光合色素含量及阿尔冈金类胡萝卜素外,各参数均未能恢复到对照水平,因此旱后复水不能完全解除干旱对PSII反应中心所带来的伤害.紫花苜蓿幼苗对干旱胁迫较为敏感.供试品种相比,陇东苜蓿耐旱性优于阿尔冈金.     

鲜茧茧层含水率测定仪的研制

在测试鲜茧茧层含水率与其导电电阻存在高度线性对数关系基础上，研制出鲜茧茧层含水率测定仪，实现了不削茧就能准确快速测定鲜茧茧层含水率。     

穴播条件下株行距对紫花苜蓿种子产量和质量的影响

在甘肃省酒泉市研究了穴播条件下不同株、行距处理对紫花苜蓿种子生产性能的影响，结果表明：在产种第一年（2004年）行距和株距对种子产量和产量构成因素均产生了显著的影响（P〈0．05），随着行距从60cm递增至100cm，种子产量也随之从1240kg／hm^2下降到982kg／hm^2，而各株距处理的种子产量则从15cm的1426kg／hm^2依次递减至60cm的807kg／hm^2；行距60cm和株距15cm组合的产量最高，为1833kg／hm^2，100cm行距和株距60cm组合的产量最低，为753kg／hm^2。株行距的增加显著降低了枝条密度，但结荚花序数／枝条和荚果数／结荚花序却显著提高。品种间种子产量的差异不显著。品种间的结荚花序数／枝条、种子重量、正常种苗率、发芽势和硬实率存在显著的差异（P〈0．05）。     

含水量和乳酸菌制剂对狗尾草发酵品质的影响

研究含水量(30%、35%和40%)和乳酸菌制剂添加量(3%、6%、9%和12%)对成熟期狗尾草(Setariaviridis(L.)Beauv.干草发酵品质的影响。结果表明,在含水量30%条件下添加乳酸菌制剂显著降低粗蛋白质含量(P<0.05);含水量35%和40%条件下添加乳酸菌制剂显著降低粗纤维和中性洗涤纤维含量(P<0.05);随着含水量的升高pH值趋于降低,乳酸、丁酸产量趋于增加;含水量和乳酸菌制剂对pH值、乳酸产量以及乳酸菌数量具有显著的互作效应(P<0.05);在含水量30%-40%条件下,添加乳酸菌制剂3%-12%,各处理组的发酵品质均为优或良。     

Mussel shells as an environment enrichment and calcium source for floor-housed laying hens

Feather pecking is still a behavioral problem in laying hen flocks, resulting in impaired welfare and economic losses. Environment enrichment, e.g., providing access to litter, to increase foraging behavior in laying hens has been shown to decrease feather pecking. This study investigated the effect of spreading crushed mussel shells (particle size 10 to 20 mm) in the litter area as an environment enrichment and source of calcium for layers receiving a commercial feed and for layers given a feed with 40% less calcium. These treatments were compared with a control involving hens given the commercial feed, but no mussel shells in the litter. The study included 900 Dekalb White layers housed in a single-tier floor system during a production cycle (20 to 72 wk of age). The mussel shells were consumed to a lower extent than predicted, resulting in calcium deficiency in hens fed the low-calcium diet. This in turn was evident as increased degree of keel bone deviations and lower eggshell breaking strength. Daily addition of crushed mussel shells to the litter for laying hens on a balanced or calcium-deficient diets did not generate any positive effects on bird feather cover, eggshell quality, production performance, or fearfulness. Hence, with the particle size of mussel shells used in this study, there was no indication of improved welfare due to environment enrichment.