Effects of dietary tryptophan and stocking density on the performance,meat quality,and metabolic status of broilers

Background

Highly automated cage-rearing systems are becoming increasingly popular in China. However, a high stocking density can cause oxidative stress and decrease broiler performance. The tryptophan (TRP) derivative 5-hydroxytryptophan (5-HT) has been shown to preserve membrane fluidity in birds suffering from oxidative stress. Therefore, this experiment was conducted to determine the effects of dietary TRP supplementation on performance, breast meat quality and oxidative stress in broilers reared in cages with a high or low stocking density.

Methods

Female Arbor Acres broilers (25-d-old, n = 144) were randomly allocated to 1 of 4 treatments. The birds were fed a diet based on corn, soybean meal, cottonseed meal and corn gluten meal containing either 0.18 or 0.27% TRP and were housed with stocking densities of 11 or 15.4 birds/m² in a 2 × 2 factorial experiment. Broiler performance was evaluated from d 25 to 42. Eight birds from each treatment were slaughtered on d 42 and plasma and breast muscle samples were collected to measure biochemical indices.

Results

A higher stocking density tended to be associated with reduced weight gain (P < 0.10), and significantly increased plasma glutamic-pyruvic transaminase (GPT) activity (P < 0.001). Increased dietary TRP significantly reduced the activities of lactic dehydrogenase and GPT while increasing total cholesterol in the plasma (P < 0.01), reducing drip loss of breast muscle (P < 0.10) and improving feed efficiency (P < 0.10).

Conclusions

An increase in dietary TRP, 1.5-fold higher than the standard supplementation level, can alleviate oxidative stress as well as improve welfare and feed efficiency in broilers reared in cages with a high stocking density.     

外荡网箱养鳗试验

鳗鲡(Ahguilla japonica Temm.et Schl.)又名河鳗、白鳝，属淡水鱼珍品。国际市场畅销，为我国水产创汇的拳头产品．我国台湾50年代初建场养鳗，现可年产商品鳗约3．5万吨。大陆自1972年发展成鳗养殖，目前年产5千吨以上．绝大多数为露天或温室池塘。网箱养鳗始于1987年，是浙江针对本地气温偏低，又映地热、工厂余热，但有众多的水库和外荡，因一种紧迫感创造出来的新技术外荡网箱养鳗．嘉兴历来以出口鳗苗为主。本地却有1．8万公顷外荡可供利用．因为网箱养鳗在外荡比水库有更多技术难题，故有“外荡网箱养鳗不可行”之说，为此，从事研究适于外荡网箱养鳗的整套的技术。历时三年，于1990年完成．由于试验从观察外荡生态变化及河鳗生活入手，因势利导试用某些新技术和配套混养，充分利用与发挥生态效益，最终才有较好的技术经济效益。     

急升温对十种甲壳动物存活率的影响

温度是影响海洋生物生长繁殖和分布的一个重要因子。在适温范围内,生物可以正常生长繁殖;超过适温范围时,生物的行为活动以及生长繁殖都将受抑制,甚至导致死亡。张伟权等(1980)、王克行等(1984)曾观察过温度对中国对虾幼体存活率和生长的影响,黄加祺和郑重(1986)、林森杰和李松(1988)、Bhattacharga(1984)、Bradley(1975)、Moreira(1982)分别报道过温度与某些桡足类生长、繁殖及存活率关系的实验结果。有关虾、蟹等经济动物和浮游甲壳类的行为生态与分布,不少学者已作过较细致的研究和论述。     

小窑湾浮筏养殖区底质沉积物初步研究

20 0 0年 10月对小窑湾底质沉积物进行了 10个项目的海上调查 ,结果表明 :小窑湾底质重金属含量均为国家一类标准 ,符合渔业生产条件 ;硫化物、有机质含量虽然为国家一类标准 ,但已趋于上限 ,说明底质已被污染 ;油类已达国家二类标准 ,超出了渔业生产的许可范围 ;底质沉积物中每天向海水中释放的氮为 12 936mg/(m2 ·d) ,释放的磷为 0 4 95mg/ (m2 ·d)。     

Effect of dietary vitamin C supplementation on the oxygen consumption, ammonia-N excretion and Na/K ATPase of Macrobrachium nipponense exposed to ambient ammonia

The 96-h LC₅₀ of ammonia-N and the effects of dietary vitamin C on oxygen consumption, ammonia-N excretion and Na⁺/K⁺ ATPase activity of Macrobrachium nipponense exposed to ambient ammonia were investigated. The results showed that the 96-h LC₅₀ of ammonia-N was 36.6 mg l⁻¹ for the freshwater prawn, M. nipponense, at pH 8.0. When prawns were exposed to high ambient ammonia-N concentrations, the oxygen consumption rate increased and ammonia excretion decreased. Dietary vitamin C supplementation led to higher oxygen consumption and lower ammonia excretion. Na⁺/K⁺ ATPase activity increased with increased ambient ammonia-N exposure in the range of 0–18.3 mg l⁻¹, and then was reduced at ambient ammonia-N 36.6 mg l⁻¹. Na⁺/K⁺ ATPase activities of prawns fed a vitamin C-supplemented diet were significantly lower than those of prawns fed a diet which was not supplemented with vitamin C.     

Mechanical and thermal properties of epoxy composites containing graphene oxide and liquid crystalline epoxy

The graphene oxide (GO) sheets are chemically grafted with γ-etheroxygentrimethoxysilane (KH560) and liquid crystalline epoxy (LCE) is synthesized from 4,4′-bis(2-hydroxyhexoxy)biphenyl (BP₂) and epichlorohydrin before being incorporated into epoxy matrix. Then we present a novel approach to the fabrication of advanced polymer composites from epoxy matrix by incorporation of two modifiers, which are grafted GO (g-GO) and LCE. The mechanical properties of epoxy composites are greatly improved by incorporating LCE/g-GO hybrid fillers. For instance, the addition of 3 wt% hybrid filler (2 wt% g-GO and 1 wt% LCE) into the epoxy matrix resulted in the increases in impact strength by 132.6 %, tensile strength by 27.6 % and flexural strength by 37.5 %. Moreover, LCE/g-GO hybrid fillers are effective to increase thermal decomposition temperature, glass transition temperature, and storage modulus by strong affinity between the fillers and epoxy matrix.     

刈割高度对多花黑麦草新品种产量和品质的影响

为探讨不同刈割高度对多花黑麦草新品种饲草产量和品质的影响,以2个多花黑麦草新品种为对象,采用5个刈割高度分别测定2个品种的鲜、干草产量、粗蛋白、可溶性碳水化合物(WSC)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和干物质体外可消化率(IVDMD)。结果表明:在65 cm时刈割,所获得的鲜、干草产量最高;随着刈割高度的增加,2个黑麦草品种的粗蛋白和可溶性碳水化合物含量呈抛物线趋势变化,在刈割高度为55 cm时达到最高值;中性和酸性洗涤纤维含量则随着刈割高度的增大逐渐增加;干物质体外消化率亦呈现抛物线的趋势,在刈割高度为65 cm时达到最高。2个品种的表现规律一致。     

保水剂和氮肥对小粒咖啡生长及水分利用的互作效应

小粒咖啡生产经常受到季节性干旱和土壤营养不足的制约。为探讨小粒咖啡节水抗旱和水肥资源高效利用模式,采用3个保水剂水平和3个施氮水平,研究了保水剂和氮肥对小粒咖啡苗木生长及水分利用的影响。结果表明:低氮、低保处理可以获得小粒咖啡苗木的最大生长量(株高、茎粗及叶面积)。和对照(无氮处理)相比,低氮可使干物质累积量提高24.10%,而高氮减少干物质累积11.95%。和无保水剂处理相比,低保水剂提高干物质累积11.53%,而高保水剂抑制干物质累积8.65%。此外氮肥和保水剂能不同程度地降低日蒸散量,提高水分利用效率;施氮和保水剂可分别提高小粒咖啡水分利用效率2.72%~35.37%和8.48%~20.24%。小粒咖啡氮素累积量随着施氮量增加先增后降。过高水平保水剂和氮肥都会对小粒咖啡的苗木生长产生明显的抑制作用,而低氮低保处理可同时提高干物质累积和水分利用效率。     

山蚂蝗属(Desmodium Desv.)种质资源形态多样性研究

对37份山蚂蝗材料的植物学特征、外部性状的变异及其规律进行观测统计及聚类分析。通过数据统计和相关性分析,结果表明:(1)山蚂蝗的植物学特征存在广泛变异,其变异系数为85%(叶柄长)~9%(叶色),平均为45%;(2)山蚂蝗植物学各性状指标间存在不同程度的相关性,其中叶片类型、叶尖、花冠颜色、茎的生长习性、旗瓣大小、荚果长、荚果宽、单荚粒数之间存显著(p0.05)或极显著(p0.01)正相关,叶长与叶宽正相关系数最大(0.892);叶片类型与叶长、叶宽、花序轴长度成极显著负相关,系数分别为-0.611、-0.462、-0.485。通过聚类分析,在欧氏距离8.0处,可将37份供试山蚂蝗材料划分为6类,其中度尼山蚂蝗CIAT46562和灰色山蚂蝗CPI46561单独聚为一类,为直立或斜升、羽状三出复叶型。     

50％噻苯隆可湿性粉剂对鲁中地区棉花的脱叶及吐絮效果

为科学使用棉田脱叶催熟剂,2012年在山东省泰安肥城市安驾庄镇大龙岗石村进行了50％噻苯隆可湿性粉剂对棉花脱叶催熟田间药效试验。田间试验结果表明,50％噻苯隆可湿性粉剂（有效成分）225～300g·hm^-2的用量可显著提高棉花的脱叶率及棉铃的吐絮率;棉花品质和测产结果表明：施用50％噻苯隆可湿性粉剂可提高子棉产量,且对棉花的品质没有影响。