安格斯肉牛与牦牛杂交及其效果研究

［目的］为了进一步优化牦牛肉品质,有效缩短牦牛养殖周期,提高其受胎率和犊牛成活率。［方法］本研究进行了安格斯肉牛与牦牛杂交试验,,利用安格斯肉牛冷冻精液,对251头经产母牦牛进行了人工授精。［结果］人工授精后,分别于2013年产犊42头,成活率66.67%;2014年产犊51头,成活率95.7%;2015年产犊67头,成活率91.04%。［结论］牦牛膘情较好时期,受胎率可达83.33%,接近于奶牛人工授精的受胎率,达到了青海省牦牛人工授精的较高水平。     

体外受精温度、时间及卵子质量对延边黄牛受精卵体外发育的影响

本研究探讨了体外受精温度、时间及卵子质量对延边黄牛卵母细胞体外受精后体外发育的影响。试验结果表明，体外受精温度为39℃、体外受精时间12h时，卵裂率、囊胚发育率及囊胚孵化率最佳；卵子的质量对受精卵体外发育的影响很大。     

Sulfadimidine metabolism in vitro: II. comparative studies in cultured rat, goat, sheep and cattle hepatocytes

van't Klooster, G.A.E., Blaauboer, B.J., Noordhoek, J. & van Miert, A.S.J.P.A.M. Sulfadimidine metabolism in vitro: II. comparative studies in cultured rat, goat, sheep and cattle hepatocytes. J. vet. Pharmacol. Therap. 16, 454–461.
Hydroxylation and acetylation of sulphadimidine (SDD) and the deacetylation of N4-acetyl SDD was investigated in cultured hepatocytes from male and female rats, from male and female goats and from female sheep and cattle. Significant sex differences were observed for hydroxylation of SDD in hepatocytes from rat and goat. In goat, sheep and cow hepatocytes, the hydroxylation pathway is relatively important, whereas in rat hepatocytes, acetylation is predominant. Hepatocytes of all four species deacetylated N4-acetyl SDD. In ruminant hepatocytes, deacetylating activity was of considerable importance, whereas in rat hepatocytes, it appeared a minor pathway of metabolism. Similar to the in vivo situation, formation of N4-acetyl SDD in cultured hepatocytes results from an equilibrium of acetylation and deacetylation. A good correlation was found between results in isolated hepatocytes and previous findings in vivo , both in levels of species-related activities and in acetylation-hydroxylation ratios. In conclusion, cultured hepatocytes appear a useful in vitro model to study comparative sulfonamide metabolism.     

An evaluation of the effect of clotting on the relationship between copper and caeruloplasmin in bovine blood

The ratio of caeruloplasmin activity to copper concentration (CP:Cu) has been suggested as a more accurate determinant of the requirement for additional copper than plasma or liver copper concentrations. Although this test has no peer-reviewed evidence of efficacy, it has been used by a large number of UK veterinarians. However, the available test uses a serum caeruloplasmin (sCP) activity to plasma copper (pCu) concentration ratio which, because of the preferential loss of caeruloplasmin during clotting, is likely to underestimate the true CP:Cu, although it has been suggested that the marginal range accounts for this. This study was undertaken to evaluate the effect of using serum copper (sCu) rather than pCu concentrations in calculating CP:Cu. Using sCu rather than pCu increased CP:Cu by more than was accounted for by the marginal range. Of 48 cattle which were reported as 'low' using sCP:pCu, 22 were 'normal' when sCu was used instead of pCu. All herds with 'marginal' or 'low' mean CP:Cu when the sCP:pCu concentration ratio was used had 'normal' ratios when sCu was used instead of pCu.     

The effect of Rumensin on mineral metabolism and on the conversion of nutrients in feedlot cattle

A study on mineral metabolism and conversion of nutrients by applying sodium monensinate, 125 mg per head and day, in cattle fattening was performed. This experiment was realized under production conditions in the fattening station of pavillion type for 367 days and included 985 bulls of Bohemian Spotted cattle. The feed ration consisted of maize silage with addition of dried poultry bedding and concentrates. At the beginning of the experiment the appetite antipathy was observed, the adaptation period lasted 4 weeks. During the adaptation period the weight gains decreased; after adaptation of animals to monensin the weight gain not only counter-poised, but in comparison with the control it increased. Throughout the experiment no health disorders connected with the applied additive were observed. In the rumen fluid the content of calcium, magnesium, phosphorus, zinc, copper and iron was followed. In the blood plasma the levels of sodium, potassium, calcium, magnesium, phosphorus, zinc, copper and iron were followed. The application of sodium monensinate did not affect the followed parameters of mineral metabolism. The experiment was aimed at the evaluation of production and operational parameters with a view to the weight gain and feed conversion. In the experimental group the weight gain was higher by 3.85%. The saving of maize silage in the experimental group amounted to 5.8%, by using of this additive the saving of concentrates amounted to 1.35%. In the experimental group the feed conversion converted to dry matter increased by 7.12%. Sodium monensinate at the dose of 125 mg per head and day had positive effect on the followed production and economic parameters.     

卵巢保存温度、激素及体外培养时间对延边黄牛卵母细胞体外成熟的影响

本研究探讨卵巢保存温度、激素及体外培养时间对延边黄牛卵母细胞体外成熟的影响.研究结果表明,将卵巢分别保存在25～29℃、30～35℃、36～40℃的生理盐水中运输时,卵母细胞体外成熟率分别为55.3%、70.1%、60.7%,各组间无显著性差异(P＞0.05);当将卵母细胞分别培养在无激素的对照组(TCM199 10?S)、添加雌二醇(estradiol)-17β组、LH 雌二醇-17β组时,卵子的成熟率分别为57.8%、64.3%、70.1%,对照组与LH 雌二醇-17β组差异显著(P＜0.05);卵母细胞各自培养22～25 h、26～30 h、31～34 h时,卵子体外成熟率分别为56.3%、65.4%、68.4%,3组间无显著差异(P＞0.05).     

The effect of tetrathiomolybdate upon sheep caeruloplasmin amine oxidase activity in vitro: the influence of substrate on apparent sensitivity to inhibition.

The effect of molybdate, dithiomolybdate, tetrathiomolybdate and diethyldithiocarbamate on caeruloplasmin amine oxidase activity was examined using o-dianisidine as a substrate. Enzyme activity was strongly inhibited by tetrathiomolybdate (1.5 X 10(6)M), oxidation of another substrate, p-phenylenediamine, was inhibited only slightly.     

Divergent selection for postweaning feed conversion in Angus beef cattle: II. Genetic and phenotypic correlations and realized heritability estimate.

A single generation divergent selection study, replicated four times (1983, 1984, 1985, and 1986), was conducted to assess genetic differences between progeny of high and low feed conversion sires in Angus beef cattle and to determine correlated response for weight gain (ADG140), feed intake (AVFD140), and BW (OFFTSTWT) in a time- (140-d) and fat-constant (8.9 mm) period. Realized heritability estimates for unadjusted (feed/gain; FEFF140; .26) and adjusted feed conversion (adjusted as recommended by the BIF, 1986; ADJFDEFF; .46) were obtained. The difference in heritability estimates reflects variation accounted for by adjustment for BW differences, and thus maintenance requirements, of individual progeny. Phenotypic and "pseudo" realized genetic correlations of FEFF140 with ADG140, AVFD 140, and OFFTSTWT were -.33 and -.66, .49 and -.26, and .15 and -.41, respectively. Phenotypic and "pseudo" realized genetic correlations of ADJFDEFF with ADG140, AVFD140, OFFTSTWT, and FEFF140 were -.54 and -.59, .30 and -.23, .27 and -.36, and .97 and .49, respectively. Subcutaneous fat (as estimated by ultrasonic measurement; BF140) had phenotypic and "pseudo" realized genetic correlations with FEFF140 of -.33 and .66, respectively, and with ADJFDEFF of -.44 and -.58, respectively.     

Relationships between the concentrations of trichloroacetic acid-soluble copper and caeruloplasmin in the serum of cattle from areas with different soil concentrations of molybdenum

The concentrations of trichloroacetic acid (tca)-soluble copper and caeruloplasmin were determined in 345 serum samples taken from cattle in March 1998 by eight Scottish Agricultural College veterinary disease surveillance centres serving areas with soils ranging from being 'high' in molybdenum (Thurso) to 'low' (Perth and St Boswells). The mean concentrations varied significantly between the centres, with Thurso having the lowest values for both variables. There were strong linear regressions (r>0.8) between caeruloplasmin and tca-soluble copper for each centre but no significant differences in slope or intercept between the areas with the highest and lowest soil molybdenum, and the pooled regression accounted for 88 per cent of the variation. The distribution of the ratios of caeruloplasmin to tca-soluble copper, unlike those of the individual variables, was not normal, and 70 per cent of the values fell within 10 per cent of the mean ratio of 20.3 mg/micromol and close to the 22 mg/micromol copper expected in pure caeruloplasmin. Low ratios were generally associated with low tca-soluble copper. Ratios above 24 were found in 8 per cent of the samples and were probably attributable to acute-phase reactions and the non-specificity of the assay for caeruloplasmin.     

奶牛氨基酸营养及其对乳蛋白分泌的影响

乳蛋白是一种营养价值很高的蛋白质 ,它的氨基酸含量和构成比例基本上与人体所需氨基酸的数量、比例相近。然而长期以来我国奶牛育种工作过分强调产奶量和乳脂率两项生产性能指标 ,而忽视了乳蛋白的选育 ,因此奶牛乳蛋白浓度始终较低。近些年随着研究的不断深入 ,人们发现 ,牛奶中含有大量的高度饱和脂肪酸助长了胆固醇的循环水平 ,增加了心血管疾病的发生率 ,同时人们也发现 ,乳蛋白除给新生动物和人类提供蛋白、氨基酸外 ,某些乳蛋白及其消化产生的肽类活性物质还具有特定的生理功能。目前世界很多国家低脂乳销售比例均在逐年增加 ,并且世…     

An evaluation of milk temperature measurement for detecting oestrus in dairy cattle. II variations in body and milk temperature associated with oestrus

Vaginal and milk temperatures were measured at each milking in 15 postpartum Friesian cows showing recurrent oestrous cycles for a total of 33 oestruses. A significant increase (P<0.001) in both vaginal and milk temperature of 0.29±0.05°C was shown between the milking prior to oestrus and the milking when oestrus occurred. Cows were divided into 3 groups: showing either a definite temperature rise (27% of cases), a limited temperature rise (60%) or no temperature change (13%) associated with oestrus. Various methods of analysis were investigated to determine the usefulness of the milk temperature data for oestrus prediction. The optimum compromise of high oestrus detection rate (73.3±16%) and lowest percentage of false positives (10.8±3.0%) was based on a temperature rise on the day of oestrus of 0.2°C over the corresponding mean temperature of the preceding three days. These rates suggest the measurement of milk temperature is less useful for oestrus prediction than some earlier reports have indicated.