In ovo feeding of nutrients and its impact on post‐hatching water and feed deprivation up to 48 hr,energy status and jejunal morphology of chicks using response surface models

A Box–Behnken design (BBD) in a response surface methodology (RSM) was used to investigate the response of broiler chicks to in ovo feeding (IOF) of beta‐hydroxy beta‐methylbutyrate (HMB), dextrin and the timing of the first water and feed deprivation. On day 18th of incubation, 1,500 eggs were randomly assigned to 15 experimental runs of BBD, each with 4 replicates, as 3 levels IOF of HMB (0%, 0.5% and 1%) and dextrin (0%, 20% and 40%), and 3 levels of the first water and feed deprivation (6, 27 and 48 hr). Day‐old chicks from each replicate were then used to assess the effect of IOF and time first water and feed access on chick's responses. The IOF of dextrin leads to respectively 9.7%–15.5% lower hatchability for 20% and 40% inclusion (p < .05), whereas HMB inclusion appeared with no effect on hatchability (p > .05). Administration of dextrin or HMB into the amnion of embryos elevated length, width and surface area of villus, and increased glycogen content of liver and breast (p < .05). In all parameter models, the linear terms showed highest contribution (R² = 0.81–0.97) to explain existing variation in chick's responses. The first water and feed deprivation had largest effect on BW2 and glycogen content of liver and breast. It is concluded that if possible, place chicks before 7 hr of hatch to preserve BW loss and have maximum response from IOF. If not possible, use IOF with 40% dextrin + 0.5% HMB to preserve gut integrity and energy status up to 48 hr. This should give advantage to chicks to recover fast after feeding, but that would have to be confirmed by trials growing birds to slaughter age.     

黄鳝线粒体DNA的提取及其酶切分析

用碱裂解法从黄鳝肝脏组织中提取线粒体DNA,并对提取的线粒体DNA纯度、完整性进行了检测.结果表明,其紫外吸收比值为OD26/280在1.72～1.96之间,纯度较高,琼脂糖凝胶电泳表明提取线粒体的完整性好;用EcoR Ⅰ和HindⅢ对黄鳝线粒体DNA进行酶切,用琼脂糖凝胶电泳检测,均能检测出两套不同的酶切片段,证明黄鳝线粒体DNA存在多态性.     

根域限制对‘峰后’葡萄果实韧皮部糖卸载的影响

 为了探明根域限制提高葡萄果实糖度的机制,用5 年生‘峰后’葡萄为材料,在果实成熟 期用“浆果杯”技术比较了根域限制处理与对照的果实韧皮部糖卸载的日变化。结果表明,葡萄果实韧 皮部糖卸载在一天中有3 次高峰,分别出现在上午、下午和晚上（9：00、17：00 和21：00 左右）。上午 卸载量大,其峰值分别为下午和晚上的2.1 和1.4 倍左右;根域限制处理果实的糖卸载量始终高于对照, 约为对照的1.5 倍,并且上午糖的快速卸载提前了3 h,峰值为对照的2.0 倍。给“浆果杯”中的糖卸载 缓冲液添加ABA、EGTA,促进了糖卸载,但添加EB 却抑制糖卸载。表明葡萄果实韧皮部糖卸载需要消 耗能量,根域限制促进了葡萄果实韧皮部的糖卸载,并可能与其诱导ABA 含量的升高有关。     

营养限制对水貂补偿生长的影响

选取55只健康、体重相近的生长期水貂,随机分成5组,每组11只,进行了为期90d的试验。前50d饲喂基础日粮和基础日粮中的玉米粉分别用8．88％、17．77％、26．65％、35．53％的葡萄糖代替,同时添加适量的玉米蛋白粉制备成的5种等氮日粮。然后,各组均饲喂同样的鲜料。试验期间,每10d测1次体重,并记录,以研究营养限制对生长期水貂补偿生长的影响。试验结果表明：恢复常规饲喂后所有水貂体重都迅速增长,但是差异不显著（P〉0．05）。营养限制程度较重的第5组在补偿生长阶段体重增长较快,且超过限制程度较轻的组。在补偿生长后期,第Ⅳ、Ⅴ组的特定生长率较体重低的组显著下降（P〈0．05）。     

传染性法氏囊病病毒(IBDV)快速检测与分型技术

根据已发表的传染性法氏囊病病毒 (IBDV)核苷酸序列 ,在病毒结构蛋白 VP2编码基因的高变区两端外侧的保守序列内设计合成了 2条寡核苷酸引物 ,对各种不同致病性的 12株参考毒株进行了 RT- PCR检测。结果 :12个参考毒株均能扩增出约 6 79bp的目的片段 ,而对照的 5种鸡源性病原体 NDV、IBV、CAIV、E.coli、PM均未扩增到相应片段 ;对疑似 IBD的 34份临床病料进行检测 ,并同时在其扩增的片段内设计另 1对引物进行 Nested- PCR检测 ,结果基础 RT- PCR检测到 11份阳性 ,Nested- PCR检测到 2 3份阳性 ,后者的检出率大大提高。结果表明 ,建立的 RT- PCR诊断技术具有特异、快捷、敏感的特点。取限制性内切酶 Sac 和 Ssp 以及设计的 2条 vv IBDV(超强毒株 )特异性引物 ,分别应用 v VP2片段 PCR扩增产物的限制性内切酶分析和型特异性引物的 PCR扩增 2种方法 ,对 7个 IBDV分离参考毒株和 2 4个临床样品进行致病性分型。结果 ,确定 2 1株属于 c IBDV(经典毒株 ) ,8株属于 vv IBDV,2株未能确定 ;2种分型方法的结果基本一致 ,均可用于 IBDV的快速分型 ,型特异性引物的 PCR扩增方法更为简便和快捷     

Comparison of the Value of Pulsed-field Gel Electrophoresis,Random Amplified Polymorphic DNA and Amplified rDNA Restriction Analysis for Subtyping Taylorella equigenitalis

Eight strains of Taylorella equigenitalis were identified by a polymerase chain reaction using a primer pair specific to the 16S rDNA of T equigenitalis. These eight strains were chosen because they had previously been shown to represent eight distinct genotypes by pulsed-field gel electrophoresis analysis after separate digestion of the genomic DNA with ApaI or NotI. The eight strains could be classified into six or seven types by random amplified polymorphic DNA analysis using different kinds of primers. Amplified rDNA restriction analysis after separate digestion with five restriction enzymes, including AluI and MboI, of the 1,500 bp fragments of rDNA amplified by polymerase chain reaction did not discriminate the genomic variations among the eight strains of T equigenitalis. Thus, pulsed-field gel electrophoresis was shown to discriminate these eight organisms better than random amplified polymorphic DNA analysis, while amplified rDNA restriction analysis was found to be unsuitable for subtyping T equigenitalis.     

早期数量限饲对肉用仔鸡生产性能、胴体品质的影响

试验研究了早期数量限饲对肉用仔鸡生产性能、胴体品质的影响。以320只1日龄AA+肉用仔鸡为试验动物。设4个处理组,每个处理组4个重复,每个重复20只肉仔鸡。对照组根据AA+商品代肉鸡营养标准配制。各处理肉用仔鸡1～7日龄均为自由采食,8～14日龄对照组、限饲90%组、限饲80%组和限饲70%组分别饲喂自由采食量的100%、90%、80%和70%,15日龄恢复自由采食,以后按常规饲养管理。每周末,以重复为单位全部称重。分别于42、49日龄,每个重复随机抽取4只肉用仔鸡禁食12h、称重、屠宰、测定屠体品质。试验结果表明:在第2周,限饲各组肉仔鸡的体重和日增重分别显著低于对照组(P0.05);在第3周,限饲90%组完成补偿生长,体重与对照组差异不显著(P0.05);在第4周,限饲80%和70%组完成补偿生长,体重与对照组差异不显著(P0.05);5、6、7周及2～6、2～7周各组在体重、日增重、日采食量和饲料转化率等都无显著差异(P0.05)。早期数量限饲对肉仔鸡胴体特性没有显著影响(P0.05),限饲70%～80%,具有改善饲料转化效率、胸肌率、腹脂率的作用。     

Effect of feed restriction on dairy cow milk production: a review

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes. The study of FR is also of interest since with climate change issues, cows may be increasingly faced with periods of drought leading to a shortage of forages. The aim of this article is to review the effects of FR during lactation in dairy cows to obtain a better understanding of metabolism changes and how it affects mammary gland activity and milk production and composition. A total of 41 papers studying FR in lactating cows were used to investigate physiological changes induced by these protocols. FR protocols affect the entire animal metabolism as indicated by changes in blood metabolites such as a decrease in glucose concentration and an increase in non-esterified fatty acid or β-hydroxybutyrate concentrations; hormonal regulations such as a decrease in insulin and insulin-like growth factor I or an increase in growth hormone concentrations. These variations indicated a mobilization of body reserve in most studies. FR also affects mammary gland activity through changes in gene expression and could affect mammary cell turnover through cell apoptosis, cell proliferation, and exfoliation of mammary epithelial cells into milk. Because of modifications of the mammary gland and general metabolism, FR decreases milk production and can affect milk composition with decreased lactose and protein concentrations and increased fat concentration. These effects, however, can vary widely depending on the type of restriction, its duration and intensity, or the stage of lactation in which it takes place. Finally, to avoid yield loss and metabolic disorders, it is important to identify reliable biomarkers to monitor energy balance.     

早期限饲对肉鸡肌肉生长及生产性能的长期影响

本研究旨在比较不同生长阶段隔日限饲(早期限饲:1~14日龄限饲,后期限饲:50~63日龄限饲)对肉鸡肌肉生长及相关激素水平的影响,并探讨早期限饲对肉鸡肌肉生长的程序化作用。试验结果:1)早期限饲组整个试验阶段体重均极显著低于对照组,后期限饲组限饲一周后体重显著低于对照组并于63日龄实现完全补偿生长;2)早期限饲组14日龄和63日龄胸肌、腓肠肌重均显著低于对照组;后期限饲组63日龄胸肌、腓肠肌重均显著低于对照组,且二者与早期限饲组均差异不显著;3)早期限饲显著降低了14日龄肉鸡肌肉中DNA、RNA和蛋白含量,63日龄恢复至正常水平,且核酸、蛋白水平在胸肌和腓肠肌内的趋势表现不一致;4)早期限饲组14日龄血清中T3、T4水平均显著低于对照组,63日龄血清T3水平仍显著低于对照组;后期限饲组63日龄血清T3水平显著低于对照组,T4水平与对照组差异不显著。结果表明:1)限饲可显著阻碍肉鸡肌肉的生长;2)不同部位的肌肉对限饲的敏感度不同;3)早期营养因子对肉鸡肌肉的生长具有"程序化"作用,甲状腺激素可能参与这些过程的调节。