荷斯坦牛体型线性性状对泌乳量的主成分分析

在荷斯坦牛体型性状与泌乳量相关性分析的基础上进行主成分分析，选取累计贡献率达85％以上的前9个主成分，并进行这9个主成分与泌乳量的相关分析。结果表明，主成分I、Ⅱ是荷斯坦牛泌乳量选择时应考虑的主要指标。     

Estimation of milk production losses due to sub-clinical mastitis in dairy cattle in Costa Rica

Five dairy farms, situated on the slopes of the volcano Poás in the pre-mountain cloud forest ecological zone, Alajuela and Heredia Provinces, Costa Rica, provided data for estimation of the production losses due to sub-clinical mastitis. Within the same farm, cows with proven sub-clinical mastitis were matched with cows without signs of sub-clinical mastitis, according to breed, lactation number and days in lactation. A total of 529 cows were detected with sub-clinical mastitis, of which only 200 could be paired with control cows free of mastitis; each pair was used only once.

Crude milk production losses per cow with sub-clinical mastitis were estimated at 1.56 kg day⁻¹for daily milk yield. Milk production loss per affected quarter due to sub-clinical mastitis was estimated to be 17.6% on average. The decrease in milk production in heifers with sub-clinical mastitis did not differ significantly from the decrease in production in older cows. No significant difference in milk production loss was detected when the data were stratified on parity or the number of quarters affected.     

成都麻羊研究

本文通过对成都麻羊的系统研究。揭示了该羊皮张品质优异、肉用性能好、繁殖力强、较早熟、乳脂含量高,但泌乳力低,没有毛用价值。应归属于普通肉用山羊品种。建议充分利用其早熟、高繁殖力、乳脂率高等优良遗传性状。     

西宁部分奶牛场奶牛乳硒含量的检测及评价

采用荧光法对西宁地区三个奶牛场的29头(A,B,C 场分别为10,11,8头)奶牛的乳样进行硒含量分析。检查结果表明:A,B,C 三场平均乳硒含量分别为19.93ng/ml,21.01ng/ml,13.40ng/ml,B 场和 C 场间存在着极显著差异(P<0.01);58.62%的被检牛乳硒在20ng/ml 以下,17.24%的被检牛乳硒在10ng/ml 以下。初步证实西宁地区存在着奶牛缺硒的状况。     

外源性cAMP和cGMP对黑白花奶牛泌乳性能的影响

对泌乳黑白花奶牛分别注射cAMP+cGMP组合剂、组合剂cGMP和自制环核苷酸组合剂(cAMP+cGMP).注射当月各组奶牛产奶量无差异;注射后1月,奶牛日平均产奶量比对照分别提高14.1%、23.6%和19.7%,差异达显着水平(P<0.05).对血液和乳生化指标测定结果表明,cGMP是提高黑白花奶牛产奶量的主要调节物;环核苷酸主要通过cGMP升高血糖、加快乳腺细胞乳的合成速度,从而使产奶量提高.     

乳汁中超氧化物歧化酶(SOD)活性测定方法的研究

乳汁不但营养价值高，而且具有一定的医疗保健作用。其中含有的SOD，不但对哺育下一代是不可缺少的，而且对乳的本身也起到抗氧化的保鲜作用。水试验对影响邻苯三酚自氧化法测定SOD活性的诸因素进行了探讨，摸索出了适合于乳汁中SOD活性测定方法，为深入研究乳汁中SOD提供了重要的实验手段。     

Milk antibodies against Ostertagia ostertagi: relationships with milk IgG and production parameters in lactating dairy cattle

The present study was carried out to evaluate the relationship between milk optical density ratios (ODRs) from an indirect Ostertagia ostertagi ELISA, total milk IgG levels and milk production and then establish a correction factor to adjust ODR. Five hundred and sixty composite milk samples collected from 358 cows on four dairy herds in June and August 2002 were used in this analysis. The average ODR was 0.34. A positive correlation was found between ODR and IgG values in milk, days in milk, age and log transformed somatic cell counts (SCC). However, ODR was negatively correlated with milk production. The IgG levels and ODR values were constant from 30 to 200 days in milk. However, ODRs increased from 200 days until the end of the lactation. After controlling for age, season, herd and SCC, an increase in milk production of 13 kg/day was associated with a reduction in ODR values of 0.052. The results of the present study suggest that ODR values are not greatly influenced by production factors. ODR follow the same pattern as the IgG variation across lactation and could be adjusted in order to compare ODR values obtained from high producing cows with those obtained from low producing animals.     

Milk amyloid A: correlation with cellular indices of mammary inflammation in cows with normal and raised serum amyloid A

This study compared concentrations of amyloid A in bovine milk with the cell-based indicators of intramammary inflammation, somatic cell count and California Mastitis Test. Mammary quarter data pertaining to 180 cows were categorised according to concentrations of serum amyloid A in the cow of origin. Ranked correlation, ranked regression and receiver operator characteristics all demonstrated acceptable agreement between milk amyloid A concentrations and cell-based indices. There were some indications of reduction in this agreement, in cows with raised concentrations of serum amyloid A. However, there were also indications that serum amyloid A did not significantly influence milk amyloid A. The results of the current study indicate that milk amyloid A exhibits good correlation with established cell-based indicators of intramammary inflammation.     

A survey to identify economic opportunities for smallholder dairy farms in Bangladesh

Identified economic opportunities for planning interventions greatly increase farmers’ compliance with an extension programme. We investigated opportunities for interventions to increase dairy farmers’ income in four areas of Bangladesh, including the districts of Mymensingh, Khulna-Satkhira, Sirajgonj-Pabna and Chittagong. The data were collected from 1440 dairy farms at a one-day visit and were summarized as the difference between management targets and each herd’s calculated management indices. The average number of lactating cows, feed cost as a percentage of income from milk, milk sold as percentage of milk produced, lactating cows as a percentage of mature cows, and lactating cows as a percentage of total cattle varied from 1.5 to 3.4, from 52.5% to 92.1%, from 78.7% to 92.6%, from 81.9% to 86.7% and from 34.3% to 37.7%, respectively. The average age at first calving, calf production interval, lactation length, and milk production were 35.0–44.3 months, 14.0–17.6 months, 249–286 days and 3.5–7.2 litres, respectively, depending on the locality. The average cost for producing 100 litres of milk was 18.9–35.1 US dollars. The production cost increased when daily milk production per cow decreased (r² = 0.43–0.55). Management improvements directed towards increasing average milk production per cow per day, increasing lactation length, decreasing age to first calving, and decreasing calf production interval could expect to yield an average income increase up to a range of 676.3–1730.6 US dollars depending on the milk-producing area.     

Milk progesterone enzyme-linked immunosorbent assay as a tool to investigate ovarian cyclicity of water buffaloes in relation to body condition score and milk production

Background

Application of assisted reproductive technologies in buffaloes is limited to some extent by farmers’ inability to detect oestrus because of its poor expression. The present study aimed at investigating reliability of a milk progesterone enzyme-linked immunosorbent assay (ELISA) to assess the ovarian cyclicity during post partum, oestrus and post-breeding periods in water buffaloes.

Methods

Progesterone concentrations were measured by an ELISA in milk of 23 postpartum buffaloes in relation to oestrus, pregnancy, body condition score (BCS) and milk production. Two milk samples were taken at 10 days intervals, every month starting from day 30 and continued to day 150 post partum. BCS and milk production were recorded during sample collection. Milk samples from bred buffaloes were collected at Day 0 (day of breeding), Days 10–12 and Days 22–24. Defatted milk was preserved at −80°C until analysis. Pregnancy was confirmed by palpation per rectum on Days 70–90.

Results

Seventeen buffaloes had 47 ovulatory cycles, one to four in each, 13 were detected in oestrus once (28 % oestrus detection rate). Progesterone concentration ≥1 ng/ml in one of the two 10-day-interval milk samples reflected ovulation and corpus luteum formation. The intervals between calving to first luteal activity and to first detected oestrus varied from 41 to 123 days (n = 17) and 83 to 135 (n = 13) days, respectively. Eight buffaloes were bred in the course of the study and seven were found pregnant. These buffaloes had a progesterone profile of low (<1 ng/ml), high (≥ 1 ng/ml) and high (≥ 1 ng/ml) on Day 0, Days 10–12 and Days 22–24, respectively. Buffaloes cycling later in the postpartum period had fewer missed oestruses (P < 0.05). Buffaloes with a superior BCS had a shorter calving to oestrus interval and produced more milk (P < 0.05).

Conclusions

Milk progesterone ELISA is a reliable tool for monitoring ovarian cyclicity and good BCS may be an indicator of resuming cyclicity in water buffalo.