万古霉素分离纯化工艺研究

研究了从发酵液中纯化万古霉素的工艺.联合应用阳离子交换树脂法和大孔树脂吸附色谱法,通过比较各备选树脂的载样量、洗脱回收率、纯化倍数,优选树脂型号,确定了万古霉素纯化工艺:发酵液上PK206树脂柱,用0.1 mol/L的NH4OH溶液洗脱,收集第4,5部分(0.5 BV/部分)上CM650树脂柱,用0.3 mol/L的NH4Cl溶液洗脱,收集第6-10部分(0.5 BV/部分).收集液经纳滤脱盐、浓缩,最后产品的纯度达93.44%,总回收率为64.73%.     

鸡新城疫Ⅰ系活疫苗拌料口服免疫试验

对３２３只２～１４月龄的鸡用新城疫Ⅰ系活疫苗混在饲料中经口服进行加强免疫，这些鸡在７日龄时曾以Ⅱ系活疫苗接种过。加强免疫前，ＨＩ滴度已降到２４以下，加强免疫后３０天，ＨＩ滴度升至２５，６０天后达到顶峰，１２０天开始下降，至１９０天时为２４，到２１０天时仍保存着一些免疫力。根据这次试验，作者认为口服剂量应为注射免疫剂量的２．５～３倍。     

Response of cattle persistently infected with noncytopathic bovine viral diarrhea virus to vaccination for bovine viral diarrhea and to subsequent challenge exposure with cytopathic bovine viral diarrhea virus

Nine steers persistently infected with noncytopathic bovine viral diarrhea (BVD) virus were allotted into 3 groups (3 cattle/group). Cattle in group A were vaccinated with a modified-live BVD virus vaccine of porcine cell origin, cattle in group B with a modified-live BVD virus vaccine of bovine cell origin, and cattle in group C with a killed BVD virus vaccine of bovine cell origin. Detrimental effects due to vaccination were not seen. Six weeks after vaccination, the steers were challenge exposed with a cytopathic BVD virus. All steers developed mucosal disease after challenge exposure, produced antibodies that neutralized various isolates of BVD virus, and remained persistently infected until death. Steers given killed virus vaccine had a minimal neutralizing-antibody response and developed mucosal disease as quickly as reported for challenge-exposed, nonvaccinated, persistently infected cattle. Steers given modified-live virus vaccines had higher neutralizing-antibody response and longer intervals from challenge exposure to development of mucosal disease. The specificity of the neutralizing-antibody response differed between groups of vaccinated cattle.     

Effects of body condition score (BCS) on steroid‐ and eicosanoid‐metabolizing enzyme activity in various mare tissues during winter anoestrus

The objective of this study was to determine the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses with varying BCSs. The BCSs of twenty non‐pregnant, anoestrous mares were determined prior to euthanasia, and tissue samples were collected from the liver, kidney, adrenal gland, ovary and endometrium. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A) and uridine 5′‐diphospho‐glucuronosyltransferase (UGT) activities were determined using luminogenic substrates. The MIXED procedure of SAS was used to test the effect of BCS on enzyme activity and differences between tissues. Activity of CYP1A in adrenals was increased (p ≤ .05) in BCS 5 versus BCSs 4 and 6. Activity of CYP1A in the liver was increased (p = .05) in BCS 4 versus BCSs 5 and 6. Activity of CYP1A was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and kidney. Activity of CYP2C was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and endometrium. Activity of CYP3A was only detectable in the liver. Activity of UGT in the kidney was decreased (p = .02) in BCS 4 versus BCSs 5 and 6. Activity of UGT was threefold greater (p < .0001) in the liver than in the kidney, whereas activity of UGT was ninefold greater (p < .0001) in the kidney than in the ovary and endometrium. In general, BCS did not alter the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses. However, tissue differences in these enzymes indicated abundant hepatic metabolism in horses, which is similar to other livestock species.     

Effects of Supplementing Holstein Heifers with Dietary Melatonin during Late Gestation on Growth and Cardiovascular Measurements of their Offspring

The objective was to examine the effects of supplementing dams with dietary melatonin during late gestation on offspring growth and cardiovascular measurements. On day 190 of gestation, heifers (n = 20) were blocked by body weight and randomly assigned to one of two dietary treatments consisting of 20 mg of dietary melatonin per day [melatonin (MEL)] or no melatonin supplementation [control (CON)]. Dietary treatments were terminated on day 262 of gestation. At birth, calves were separated from their dams with no further treatments. Calf (n = 18) blood pressure, cortisol, nitrites and total antioxidant capacity were collected on weeks 0, 1, 2, 3 and 4 of age. Calf hepatic portal blood flow and concentrations of insulin‐like growth factor 1 were determined on weeks 0 and 4 of age. Calf body weight, abdominal girth, hip height and wither height increased (p < 0.05) with age. An age by treatment interaction (p < 0.01) was observed for calf body weight, which was increased at weeks 8 and 9 of age in calves born to MEL heifers compared to calves born to CON heifers. Pulse pressure, mean arterial pressure, absolute hepatic portal blood flow and blood flow relative to calf body weight were not different (p > 0.05) between treatments. A main effect of calf age (p < 0.05) was observed for concentrations of insulin‐like growth factor 1, which was decreased at week 4 compared to week 0. An age by treatment interaction (p < 0.05) was observed for cortisol, which was decreased at week 2 in calves from MEL‐treated dams compared to calves from CON‐treated dams. Early post‐natal growth was altered in offspring born to dams supplemented with dietary melatonin. This could lead to further foetal programming implications in conjunction with post‐natal development.     

畜牧工程技术在民和企业中的运用

该文结合民和企业实例,论述了“工程防疫”长效防疫体系的建立,对企业发展和产品品质提升所产生的影响。认为将畜牧工程技术导入畜牧生产的全过程,有利于保障最大限度地发挥畜禽生产潜力,推进动物养殖业的技、工、贸一体化的产业化进程,有利于中国养殖业的健康可持续发展。     

不同采收期对红星苹果虎皮病采后生理变化及品质的影响

红星苹果虎皮病的发病率高低与采收期有着极其密切的关系。从1980—1981年试验的盛花后117天、127天、138天采收的红星苹果和1981—1982年试验的盛花后130天、140天及150天采收的红星苹果来看,都一致证明采收时期愈早,虎皮病的发病率愈高。塑料薄膜封闭包装有增加红星苹果虎皮病发病率的趋势。综合红星苹果在贮藏过程中生理和品质变化以及虎皮病的发病情况,认为北京地区的红星苹果以盛花后140天左右采收为宜,并初步认为果实采收时的乙烯浓度约为1ppm合适。