基于套算法和消化率计算法估测肉鸭饲料原料代谢能的比较研究

本试验旨在研究2种计算方式对肉鸭饲料原料代谢能（ME）的影响,为采用生物学法测定肉鸭饲料原料ME时选择合适的计算方式提供参考。本研究分为2个试验。试验一：采用绝食法分5个批次测定肉鸭内源能损失的变异,同时通过排空强饲法测定10个肉鸭饲料原料配制的试验饲粮的ME,并通过2种公式计算各待测饲料原料的ME,公式1（套算法）根据基础饲粮、试验饲粮的ME及试验饲粮中基础饲粮的比例计算待测饲料原料的ME;公式2（消化率计算法）通过待测饲料原料的能量消化率乘以待测饲料原料的总能得出ME。试验二：以试验一中的10个肉鸭饲料原料配制10种验证饲粮,采用排空强饲法测定其ME,同时根据饲粮中各原料的比例及试验一中2种计算方式得出的原料ME计算饲粮的ME,比较饲粮ME计算值与实测值的差异。结果显示：1）在内源粪排泄量及内源能损失的差异上,1～3批次显著地低于4～5批次（P<0.05）,内源粪排泄量与内源能损失变异系数分别在8.21%～12.20%和9.37%～15.35%变化;2）在2种计算方式间,玉米及棉籽粕的表观代谢能（AME）和真代谢能（TME）均有显著差异（P<0.05）;3）根据公式1和...     

一氧化氮对果蔬采后保鲜机理的研究进展

近年来,一氧化氮(NO)作为一种气调保鲜剂,在果蔬采后保鲜方面逐渐引起人们的重视.从各方面阐述了NO处理对延缓采后果蔬成熟衰老的机理和效果,包括NO抑制果蔬组织内乙烯、活性氧自由基的合成,促进抗氧化酶系活性,延缓组织呼吸作用,参与介导细胞凋亡,改善果蔬的品质特征.综述了外源NO熏蒸对基因的差异性表达的影响.     

Mg17Al12、Al2Y及Al2Ca相稳定性与弹性性能第一原理研究

采用基于密度泛函理论的Castep和Dmol程序软件包,计算了Mg₁₇Al₁₂、Al₂Y及Al₂Ca相的结构稳定性、弹性性能与电子结构。形成热和结合能计算结果表明：Al₂Y具有最强的合金化形成能力和结构稳定性;热力学性质计算结果表明：在298~573 K温度范围内,Al₂Y的Gibbs自由能始终最小,其结构热稳定性最好,Al₂Ca次之,Mg₁₇Al₁₂最差,Y和Ca合金化Mg-Al系合金形成Al₂Y及Al₂Ca利于提高镁合金的高温抗蠕变性能;弹性常数的计算结果表明：3种金属间化合物均为脆性相,Mg₁₇Al₁₂的塑性最好;采用弹性常数计算结果预测的Al₂Y熔点最高,其结构热稳定性最好。态密度和Mulliken电子占据数的计算结果表明：Al₂Y结构最稳定的原因,主要源于体系在Fermi能级以下区域成键电子存在强烈的共价键作用。     

绵羊中草药饲料添加剂预试初报

为了帮助我国北方旱区或半干旱区绵羊度过草枯严寒的漫长冬、春季，开发研制一种能够提高现有草料利用率的绵羊中草药饲料添加剂。根据中兽医药学的辨证施治理论，采用小鼠日粮添加倍量秸秆粉和不同中草药复方的方法，在120只小鼠上进行了增重率和重料比的中草药复方的筛选研究。结果表明，以益气养血和消食健胃为主的两个中草药复方能够较好地改善小鼠的增重率和重料比。     

猪圆环病毒与胸膜肺炎放线杆菌混合感染的诊治

2019年3月,大庆某规模化猪场个别猪出现发育不良、咳喘、消瘦、皮肤苍白和呼吸困难等症状,随后出现死亡。为明确发病原因,降低损失,对送检病死猪进行临床症状观察、剖检及实验室检测,并对病原菌进行药物敏感性试验。检测结果为致病性胸膜肺炎放线杆菌和猪圆环病毒混合感染所致,分离的胸膜肺炎放线杆菌对阿莫西林和头孢唑高度敏感。本研究为养殖场饲养猪的死亡病因分析和防治提供了参考。     

蚓激酶成熟肽的原核表达及纯化

应用PCR技术扩增获得蚓激酶成熟肽基因，并按相应的阅读框架克隆入表达载体pGEX-4T中谷胱甘肽S-转移酶（GST）的下游。重组质粒转化大肠杆菌Rosetta株，分别在1．0mmol／LIPTG、37℃和0．1mmol／L IPTG、28℃条件下诱导，蚓激酶成熟肽-GST融合蛋白获得了高效表达，且后者得到了可溶性蛋白。经SDS-PAGE证实所表达的融合蛋白产物相对分子量与预期的53kD相符。并且以等电点和亲和层析的方法对表达出的可溶性蛋白进行了纯化。     

香精油抗蜂螨作用的研究进展

香精油及其组分具有显著的抗螨效果。萜类化合物(主要是单萜)是香精油的主要成分。占总量的90％左右。研究者通过筛选试验测定了多种香精油及其一些组分的抗螨能力。大部分表现出良好的抗螨效果。但只有少部分在蜂群试验中表现出强抗螨能力。因此，有必要对此作进一步的研究。以达到最优化目标。同时联合其它防治手段，建立一套全面的害虫防治策略，实现蜂螨的最终控制。     

Surgical outcome and ocular complications of evisceration and intraocular prosthesis implantation in dogs with end stage glaucoma: a review of 20 cases

Surgical outcome and complications following evisceration and implantation of intraocular silicone prosthesis (ISP) in 20 canine eyes with end-stage glaucoma were analyzed, including clinical signs, complications, cosmetic appearance, and owners' responses. The mean postoperative follow-up time was 312 days. Major short-term surgical complications were central corneal ulceration (6/20) and infections (3/20), while long-term complication was keratoconjunctivitis sicca (KCS) (2/20). All patient owners (100%) showed satisfied with the surgical outcome and postoperative cosmetic effect including 85% of the owners gave an excellent or good rating of satisfaction. No more medication needed for long term control except the KCS cases. With careful case selection and post-operative care, evisceration with ISP implantation proves a good and safe surgical procedure with minimal complications for end stage glaucoma.     

LPS-TLR4/MD-2–TNF-α signaling mediates alcohol-induced liver fibrosis in rats

Liver fibrosis results from liver inflammation and progresses to liver cirrhosis or liver cancer. It is known that nonalcoholic liver disease is mediated by the Toll-like receptor 4 (TLR4)/myeloid differentiation factor-2 (MD-2)–tumor necrosis factor-alpha (TNF-α) signaling pathway. This study aimed to investigate whether alcoholic liver disease is also mediated by this pathway. To this end, we first established rat models of liver fibrosis by administering alcohol. Next, the rats were injected with anti-TLR4 and anti-MD-2 antibodies. Real Time Quantitative PCR (RT-qPCR) and Western blotting were used to detect the activation of the TLR4/MD-2–TNF-α signaling pathway and hepatic stellate cells (HSCs). Moreover, the expression of molecules related to liver fibrosis was estimated. The morphology of rat liver tissue was observed through hematoxylin–eosin staining and Masson staining. For in vitro studies, Kupffer cells (KCs) isolated from the liver were transfected with si-TLR4 and si-MD-2 and co-cultured with HSCs to determine the activity of HSCs. It was found that alcohol treatment activated the TLR4/MD-2–TNF-α signaling pathway and upregulated the molecules associated with liver fibrosis. However, inhibition of TLR4 and MD-2 partially reversed this trend. Notably, in vitro studies indicated that knockdown of TLR4 and MD-2 in KCs partially inhibited LPS-induced activation of KCs and HSCs. Overall, this study showed that alcohol induces liver fibrosis via the LPS-TLR4/MD-2–TNF-α signaling pathway.     

Effects of magnesium on the performance of sows and their piglets

The objective of this study was to evaluate the effects of supplemental magnesium (Mg) on the performance of gilts and parity 3 sows and their piglets. Fifty-six gilts (Trial 1) and 56 sows (Trial 2) were assigned to one of 4 treatments according to their mating weight, respectively. The treatments comprised corn-soybean meal based gestation and lactation diets (0.21% magnesium) supplemented with 0, 0.015, 0.03, or 0.045% Mg from mating until weaning. The results showed that magnesium supplementation significantly (P < 0.05) reduced the weaning to estrus interval in both gilts and sows. There were significant effects (P < 0.05) of supplemental magnesium on the total number of piglets born, born alive and weaned in sows. In late gestation and lactation, the digestibility of crude fiber (quadratic effects, P < 0.05), and crude protein (P < 0.05), were significantly influenced by magnesium in gilts and sows, respectively. There were differences among the 4 groups in terms of the apparent digestibility of dry matter and crude fiber in sows (P < 0.05) during both early and late gestation. The apparent digestibility of gross energy was increased for sows in late gestation (P < 0.05), and lactation (quadratic effects, P < 0.05). At farrowing and weaning, serum prolactin levels and alkaline phosphate activities linearly increased in sows as the Mg supplementation increased (P < 0.05). Serum Mg of sows at farrowing and serum urea nitrogen of sows at weaning was significantly influenced by Mg supplementation (P < 0.05). The Mg concentration in sow colostrum and the serum of their piglets were increased by supplemental magnesium (P < 0.05). In addition, growth hormone levels were linearly elevated (P < 0.05) in the serum of piglets suckling sows. Our data demonstrated that supplemental magnesium has the potential to improve the reproduction performance of sows, and the suitable supplemental dose ranged from 0.015% to 0.03%.