香菇多糖的免疫调节作用及在家禽上的应用

香菇多糖是从香菇中提取分离的一种活性多糖,具有较强的免疫活性作用。本文综述了香菇多糖的免疫调节作用及其在家禽中的应用效果。     

微胶囊技术在饲料业中的应用

介绍了微胶囊技术以及饲料业中常用的芯、壁材和微胶囊化方法,并论述了微胶囊技术在饲料业中的应用。     

Changes in hormones, growth factor and lipid metabolism in finishing pigs fed betaine

An experiment was conducted to investigate the effect of dietary betaine supplementation on carcass characteristics, hormones, growth factor and lipid metabolism in finishing pigs. Forty-eight crossbred barrows and gilts (Seghers × Seghers × Duroc) weighing about 55 kg were divided into two groups, each with three replicates of eight pigs (four barrows and four gilts) per replicate, and fed corn–soybean meal basal diets supplemented with 0 and 0.125% betaine for 42 days. At trial termination, two pigs (one barrow and one gilt) weighing about 90 kg were selected from each replicate and slaughtered for analyses. The results showed that betaine increased carcass lean percentage and longissimus muscle area by 5.19% (P < 0.01) and 17.85% (P < 0.01), respectively, and decreased carcass fat percentage and average backfat thickness by 13.07% (P < 0.01) and 10.30% (P < 0.05), respectively. Serum growth hormone, insulin-like growth factor I, free triiodothyronine, free thyroxine and insulin levels in pigs fed betaine were elevated by 45.61% (P < 0.01), 55.50% (P < 0.01), 57.95% (P < 0.01), 51.80% (P < 0.01) and 42.34% (P < 0.05), respectively. Fatty acid synthase activity in the 10th rib subcutaneous adipose tissue was decreased by 24.35% (P < 0.05) with betaine supplementation, whereas hormone-sensitive lipase activity was significantly increased (P < 0.05). Meanwhile, serum free fatty acids concentration in betaine-fed pigs was 25.75% higher compared to controls (P < 0.01). The study suggested that betaine could induce changes in hormones and growth factor in finishing pigs, and therefore could inhibit fat synthesis through reducing lipogenic enzymes activities and promote fat degradation by increasing hormone-sensitive lipase activity, with a resultant decrease in adipose tissue mass and improvement in carcass characteristics.     

Characterization of polymorphisms of transferrin receptor and their association with susceptibility to ETEC F4ab/ac in pigs

Diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 (F4ab, F4ac and F4ad) fimbriae is a significant cause of mortality and morbidity in newborn and weaned pigs. The locus controlling susceptibility towards ETEC F4ab/ac has been mapped to SSC13q41, in which TFRC (transferrin receptor) was localized and considered as a positional candidate gene for ETEC F4ab/ac receptor. In this study, we determined susceptibility/resistance to ETEC F4ab/ac in a total of 755 F2 animals from a White Duroc x Erhualian intercross using a microscopic enterocyte adhesion assay. We identified two TFRC polymorphisms (SNPs 591 A>G and 632 A>G) in a single exon after comparative sequencing analysis of 2371-bp amplicons containing the complete coding region of TFRC using RNA of eight full-sib F2 animals with susceptible and resistant phenotypes. The intron sequences flanking the two exon polymorphisms were obtained, revealing an intron polymorphism (SNP 291 C>T). We genotyped the 19 founder animals of the White Duroc x Erhualian intercross for the identified polymorphisms, showing that only the 291 C>T polymorphism is a highly informative marker. We further genotyped all 59 F1 and 755 F2 animals for the 291 C>T polymorphism, and the association of this polymorphism with susceptibility/resistance to ETEC F4ab/ac in these F2 animals was evaluated by the transmission disequilibrium test. The result showed that the 291 C>T polymorphism is not a causal mutation, however, has a significant linkage disequilibrium with the ETEC F4ab/ac, especially F4ac receptor locus.     

寡糖取代抗生素对泌乳母猪血清生化指标的影响

将24头长×大二元母猪随机分为4组,每组6头,以研究基础日粮添加吉它霉素、维吉尼亚霉素和半乳甘露寡糖对其泌乳期结束时血清生化指标的影响。试验结果表明:与对照组相比,半乳甘露寡糖可以显著降低血清中甘油三酯、磷酸肌酸激酶和谷草转氨酶的活性,显著提高血清中IgM的含量,进而间接地起到提高母猪免疫能力和健康水平的作用,总体效果要好于吉它霉素,和维吉尼亚霉素相当。     

精料补充料在家兔日粮中的应用研究

选择35日龄左右、健康无病的齐卡大型白兔120只,随机分为4组,分别饲喂全价饲料和3种不同营养水平的精料补充料,观察其采食量、日增重和成活率。结果表明:饲喂青草加精料补充料较饲喂全价饲料成本低。而精料补充料以消化能12.76MJ/kg、粗蛋白19.28%、粗纤维6.21%的营养水平饲喂效果最佳。     

菜籽饼中硫葡萄糖甙的去除方法

硫葡萄糖甙(GS)是菜籽饼中主要的抗营养因子。本文对硫葡萄糖甙的性质及其降解产物的毒害作用和菜籽饼的脱毒方法进行综述。     

二甲酸钾对肉仔鸡的抗菌促生长作用研究

将120只1日龄雏鸡随机分为3组,饲养21d,比较二甲酸钾和黄霉素对肉仔鸡生产性能、肠道菌群和pH值的影响。结果表明:1)日粮中添加4.5g/kg二甲酸钾显著降低嗉囊和肌胃内容物的pH值,且显著降低盲肠乳酸杆菌和大肠杆菌数量,两者之间的比例也显著提高(P<0.05)。2)日粮中添加4.5g/kg二甲酸钾显著提高肉鸡的日增重(ADG)和饲料报酬(P<0.05),达到与黄霉素同等的效果(P>0.05)。     

二氢杨梅素对肉仔鸡生长性能、免疫器官指数及血液生化指标的影响

1日龄AA肉公雏300只,随机分为5个组,每组6个重复,每个重复10只鸡。试验Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ组在基础日粮中分别添加0%、0.025%、0.05%、0.1%和0.25%的二氢杨梅素(DMY),研究DMY对肉仔鸡生长性能、免疫器官指数及血液常规理化指标等影响。结果表明:1)日粮中添加不同剂量的DMY对肉仔鸡日增重有提高的趋势,0.05%的DMY显著提高肉仔鸡饲料转化率(P<0.01);试验期间,各组试验鸡生长发育正常,各组织器官未见异常。2)0.05%DMY显著提高21d肉仔鸡法氏囊指数(P<0.05);3)0.25%DMY组显著降低21d肉仔鸡血清总蛋白、白蛋白含量,对球蛋白无显著影响;4)0.025%、0.05%DMY显著降低21d肉鸡血清谷丙转氨酶(GPT)活性(P<0.05,P<0.01),0.025%～0.1%剂量的DMY能显著降低42d肉鸡血清GOT活性(P<0.05);5)各剂量的DMY对21、42d肉鸡血清谷草转氨酶(GOT)无显著影响。     

饲料中添加植酸酶对草鱼鱼种生长性能和磷利用率的影响

采用两因素交叉试验法,以大豆粕、棉仁粕和菜籽粕为主要蛋白源,在饲料中添加2个水平(0.75%和1.50%)的Ca(H2PO4)2和3个水平(0,500,1000 U/kg)的植酸酶,经过8周饲养试验后,结果显示:在饲料中添加500 U/kg植酸酶可使草鱼的净增重提高15.45%～18.09%,饲料系数显著降低(P<0.05),鱼体磷的贮积率增加。