烟酸对热应激条件下奶牛生产性能、血清离子浓度的影响

本试验旨在研究向日粮中添加不同水平的烟酸对热应激条件下奶牛生产性能、维持行为及血清中离子浓度的影响。试验选择健康泌乳后期中国荷斯坦奶牛3头,采用3×3拉丁方设计,在基础日粮中添加0、8、 15 g/d 烟酸,试验期63 d。结果表明：①添加8、15 g/d烟酸与对照组相比热应激奶牛的产奶量提高29.9%（P<0.05）、22.0%（P<0.05）,4%标准乳含量分别提高了28.5%（P<0.05）、21.5%（P＜0.05）,且不同添加水平间并无显著差异（P>0.05）。添加烟酸不影响奶牛的乳蛋白率、乳脂率和乳糖的水平;②添加8、15 g/d烟酸与对照组相比对热应激奶牛卧息和站立时间、排粪和排尿次数及饮水次数均无显著影响（P>0.05）,但显著提高奶牛反刍时间（P<0.05）,且不同添加水平间并无显著差异（P>0.05）;③添加烟酸8、15 g/d与对照组相比均不同程度提高奶牛血清Ca2+、K+、Na+浓度,但两添加组间无显著差异（P>0.05）;添加烟酸使奶牛血清Mg2+浓度提高,Cl-浓度降低,但未达显著水平（P>0.05）。综合分析试验奶牛生产性能、维持行为和血清离子浓度指标的变化,给热应激条件下奶牛补饲烟酸有助于缓解热应激,烟酸适宜添加量为8 g/d。     

过瘤胃烟酸对北方奶牛热应激及生产性能的影响

通过温湿度指数确定北方高温季节奶牛的生产环境,并对烟酸在北方奶牛抗热应激的应用进行了系统评价。选取体况、胎次和产奶量相近的健康奶牛30头,随机分为三个试验处理组,分别添加过瘤胃烟酸0 g·d~(-1)(对照组)、6 g·d-1(试验Ⅰ组)、12 g·d~(-1)(试验Ⅱ组)。结果表明,试验组与对照组相比奶牛体温、皮温、呼吸频率、产奶量以及乳成分方面均没有显著差异(P0.05)。这说明在日粮中单独添加6 g·d~(-1)及12 g·d~(-1)过瘤胃烟酸不会对北方夏季轻度热应激的奶牛产生显著影响。     

肉鸭对杂粕型日粮烟酸的需要

本试验采用单因子试验设计，选择10日龄健康樱桃谷肉鸭240只，按性别相同，公母各半，体重相近的原则随机分为4个处理，每个处理4个重复，每个重复15只，根据玉米一杂粕型日粮中不同烟酸含量（40ppm、60ppm、80ppm及1OOppm）分别饲喂试验肉鸭至31日龄。10～17日龄以烟酸含量为60ppm日增重较好，以烟酸含量为1OOppm日粮的料肉比较好；10～24日龄以烟酸含量为60ppm日粮日增重较好，烟酸含量为40ppm的料肉比较好；10～31日龄以烟酸含量为80ppm日粮日增重和料肉比较好。     

烟酸和烟酸铬对热应激奶牛产奶性能和血液激素水平的影响

用36头泌乳中期的荷斯坦奶牛按配对原则分为对照组、烟酸组和烟酸铬组,进行65 d的饲养试验。对照组为基础混合精料,烟酸组在混合精料中添加800 mg/kg的烟酸,烟酸铬组在混合精料中添加10 mg/kg的烟酸铬。结果表明:在夏季热应激条件下,烟酸和烟酸铬使奶牛的粗饲料采食量增加,产奶量分别比对照组提高4.86%和12.02%(P<0.05);烟酸铬组提高乳脂5.0%、乳蛋白2.8%、非脂固形物1.8%;烟酸和烟酸铬使血清PRL、T3、T4激素水平上升(P<0.05),对GLU影响不明显(P>0.05);烟酸对血清COR水平无显著影响,烟酸铬使血清COR水平降低8.80%(P<0.05)。     

Dietary niacin requirement of juvenile blunt snout bream Megalobrama amblycephala based on a dose–response study

This study aimed to determine the optimal dietary niacin requirement of juvenile Megalobrama amblycephala. Fish, with an average weight of 3.62 ± 0.02 g, were randomly divided into six groups and fed six purified diets with graded levels of niacin (0, 10, 20, 30, 40 and 50 mg/kg) three times daily for 8 weeks. The survival rate, weight gain (WG), feed conversion ratio, protein efficiency and protein retention all significantly improved (p < .05) as the dietary niacin level increased from 0 to 30 mg/kg but showed no significant difference (p > .05) with further increases in niacin levels. The supplementation of 30 mg/kg niacin also led to a significant (p < .01) reduction in the viscerosomatic index, hepatosomatic index and mesenteric fat index. The dietary niacin levels exhibited minimal effects on whole‐body moisture and ash content (p > .05) but exerted a significant (p < .05) influence on protein and lipid contents and liver nicotinamide concentrations with high values obtained in fish receiving greater than 30 mg/kg of niacin. In addition, moderate levels of niacin lowered plasma triglycerides, non‐esterified fatty acid and low‐density lipoprotein cholesterol concentrations (p < .05). Based on the broken‐line regression analysis of WG and liver nicotinamide content, the optimal dietary niacin requirement of juvenile blunt snout bream was 31.25 and 30.62 mg/kg, respectively.     

Quantifying the dietary niacin requirement of the Indian catfish, Heteropneustes fossilis (Bloch), fingerlings

A growth study was conducted to determine the dietary niacin requirement of the Indian catfish, Heteropneustes fossilis (Bloch), fingerlings (Mean weight 9.41 ± 0.18 g). Semi‐purified diets with five levels (0, 5, 10, 20 and 40 mg kg^?1 diet) of supplemental niacin were fed to H. fossilis for 15 weeks. Each diet was fed to three replicate groups of fish. Results indicated that the highest (P < 0.05) weight gain was for the fish fed the diet supplemented with 20 mg niacin kg^?1, followed by fish fed the diets with 40, 10 and 5 mg niacin kg^?1, and the lowest in fish fed the unsupplemented control diet. Patterns of specific growth rate (SGR) and protein efficiency ratio (PER) were similar to those of the weight gain. Survival of fish fed the control diet and niacin‐supplemented diet was 58% and 91–100% respectively. Niacin deficiency signs such as anaemia, anorexia, lethargy and skin haemorrhage were observed in fish fed the control diet. The haematocrit values (Ht) were higher (P < 0.05) in fish fed the diets supplemented with niacin than in fish fed the control diet. The hepatosomatic indexes (HSI) of fish fed with or without niacin‐supplemented diets were not significantly (P > 0.05) different from each other. Both body protein and lipid content were higher (P < 0.05) in fish fed the diet supplemented with 20 and 40 mg niacin kg^?1, respectively, than those fish fed other diets. The niacin content in liver significantly (P < 0.05) reflected the supplementation level in the diet and ranged from 29.11 to 40.31 mg g^?1 tissue. The associated liver niacin content for growth was about 47 μg g^?1 tissue. Quadratic regression analysis showed that the dietary niacin requirement for maximal growth of H. fossilis under these experimental conditions was about 25 mg kg^?1 diet.     

动物色氨酸与烟酸互作关系研究进展

色氨酸和烟酸在动物体内均具有很重要的生理和生化功能 ,二者存在明显互作关系 ,色氨酸可以转化成烟酸 ,其转化效率是个动态的过程 ,受多种因素影响。通过对日粮中色氨酸与烟酸适宜的添加比例关系的研究 ,探索日粮色氨酸与烟酸之间的互作规律 ,可以为经济、合理使用这两种必需营养元素提供一个配伍模式。     

尿素-麻饼型日粮条件下绵羊瘤胃内烟酸产生、消失及流通规律研究

选用3只体重为35-43 kg安装永久性瘤胃痿管、十二指肠近端瘘管的内蒙古半细毛羯羊,在饲喂尿素-麻饼型日粮条件下,通过非同位素Co标记烟酸的启动-连续灌注方法,测定绵羊瘤胃烟酸的基本产生、消失、外流速率及十二指肠的流通速率。试验结果表明:饲喂尿素-麻饼型日粮的绵羊瘤胃烟酸的基本产生速率为2．92 mg/h。通过灌注的方法提高烟酸产量后,烟酸在瘤胃内的产生速率为5．62 mg/h;消失速率为2．65 mg/h;瘤胃内烟酸的外流速率为2．97 mg/h;同时得出烟酸在十二指肠的流通速率为1．74 mg/h。     

吉富罗非鱼成鱼对烟酸的需要量

选用初始体质量为(220.16±7.66)g的吉富罗非鱼Oreochromis niloticus 360尾,随机分成6组(每组3个重复,每重复20尾),分别饲喂烟酸质量分数为11.84(对照组)、37.78、64.70、89.44、157.15、335.36 mg.kg-1的半纯化饲料10周.研究烟酸对吉富罗非鱼成鱼生长、饲料利用、鱼体营养组成、部分血清指标及肝脏烟酸累积的影响,以确定其对烟酸的需要量.结果表明,经过10周的生长,饲料中添加烟酸显著提高了试验鱼的增质量率和饲料效率(P<0.05).157.15和335.36 mg.kg-1组全鱼粗蛋白含量显著高于其他组(P<0.05);粗脂肪含量在64.70mg.kg-1组最高,显著高于对照组(P<0.05);水分与粗灰分含量各组间无显著差异(P>0.05);试验鱼血清总胆固醇、高密度脂蛋白胆固醇和总蛋白含量先升后降,在烟酸质量分数为157.15 mg.kg-1组达到最高;三酰甘油含量显著降低(P<0.05);试验鱼肝脏烟酸含量先上升后稳定,各烟酸添加组显著高于对照组(P<0.05).对增质量率、肝脏烟酸和血清高密度脂蛋白胆固醇含量回归分析,确定吉富罗非鱼成鱼获得最大生长时对饲料中烟酸的最低需要量为63.62 mg.kg-1,维持正常生理功能的需要量为158.52～172.41 mg.kg-1.     

烟酸对奶牛代谢和生产性能的影响

本文综述了烟酸的特点、营养作用机理;烟酸在奶牛体内代谢作用及对瘤胃微生物和瘤胃发酵的影响;烟酸对奶牛产奶性能、预防酮病的作用及奶牛生产中烟酸的需要量等多方面的研究。