奶牛碘缺乏症的防治

宁夏农林科学院畜牧兽医研究所许斌等 ,对４２份奶牛饲料碘 ,６份饮水碘和１３８份血清蛋白结合碘（ＰＢＴ）进行了测试。临床检查８２３头奶牛 ,选取２３２头 ,每天日粮添加０ ４１ｍｇ／ｋｇ碘 ,连续喂３００天。结果表明 ,奶牛日粮碘０ １４ｍｇ／ｋｇ,饮水碘７ ７３μｇ／Ｌ ,含碘量严重缺乏。奶牛血清ＰＢＩ测值有４２ ９９ %低于正常范围的下限２ ４μｇ／１００ｍｌ。颌下水肿奶牛ＰＢＩ为２ １３８μｇ／１００ｍｌ（ｎ＝２１） ,肉垂肿大奶牛ＰＢＩ为２ ７９８μｇ／１００ｍｌ（ｎ＝１４） ,流产奶牛ＰＢＩ为２ ２１６μｇ／１０…     

奶牛碘缺乏证及其防治试验

对４２份奶牛饲料碘、６份饮水磺和１３８份血清蛋白结合碘（ＰＢＩ）进行测试。临床检查８２３头中，选取２３２头，每天日粮添加０．４１ｍｇ／ｋｇ碘，连续饲喂３００天，探讨奶牛碘缺乏及添加效应，结果表明，奶牛日粮碘０．１４ｋｇ／ｋｇ，饮水碘７．７３μｇ／Ｌ，含碘量严重缺乏，奶牛血清ＰＢＩ测值测值有４２．９９％低于正常的下限４２．９９％低于正常范围的下限２．４μ／１００ｍＬ。进一步分析，凳下水肿奶牛ＰＢＩ为     

长×荣杂交猪体蛋白沉积模型及氨基酸需要量的预测

以长×荣二元杂交猪为研究对象，通过饲养试验和屠宰试验，测定了试验猪２０～３５、３５～５０、５０～８０、８０～１００ｋｇ阶段的生产性能和胴体无脂瘦肉生长指数（胴体无脂瘦肉沉积速度）。试验结果表明：试验猪全期日增重平均为７６２ｇ，平均日采食量２１５３ｇ，饲料报酬（Ｆ／Ｇ）２．７８７，各生产性能公母间差异不显著（Ｐ＞０．０５）；日增重与体重的回归方程为ＡＤＧ（ｇ／ｄ）＝２９３．０３＋１５．１ＢＷ－０．１　０３４ＢＷ２（Ｒ２＝０．９９８８）；试验猪全期胴体无脂瘦肉生长指数为２２７ｇ／ｄ；体蛋白沉积模型Ｙ（ｇ／ｄ）＝７２．２１１－１．５２７５ＢＷ＋０．０６４８ＢＷ２－０．０００５ＢＷ３（Ｒ２＝０．９５５）；真可消化赖氨酸需要模型Ｙ（ｍｇ／ｄ）＝８６６５．４１－１８３．３ＢＷ＋７．７７８８ＢＷ２－０．０６１２ＢＷ３＋３６ＢＷ０．７５，据此模型推算出２０～５０、５０～８０、８０～１００ｋｇ阶段真可消化赖氨酸需要量分别为９．６７、１３．６３和１１．６１ｇ／ｄ，总赖氨酸需要量为１１．１２、１５．７６和１３．４２ｇ／ｄ，真可消化赖氨酸按占风干日粮的百分比表示为０．６１％、０．５６％和０．４１％，总赖氨酸需要量按占风干日粮的百分     

《四川畜牧兽医》杂志常用计量单位标准符号及换算

量的名称单位名称单位符号换算关系量的名称单位名称单位符号换算关系量的名称单位名称单位符号换算关系长　度千米（公里）ｋｍ１ｋｍ＝１０００ｍ面　积平方米ｍ２６６７ｍ２≈１亩＊重　量克ｇ１ｇ＝１０００ｍｇ〃米ｍ１ｍ＝１００ｃｍ〃平方厘米ｃｍ２１ｍ２＝１００００ｃｍ２〃毫克ｍｇ〃厘米ｃｍ１ｃｍ＝１０ｍｍ体　积升Ｌ１Ｌ＝１０００ｍＬ浓　度百万分之一ｍｇ／ｋｇ（μｇ／ｍｇ）１ｍｇ／ｋｇ＝　　　　　１×１０－６＝１ｐｐｍ＊〃毫米ｍｍ１ｍｍ＝１０００μｍ〃毫升ｍＬ光照度勒克斯Ｌｘ〃微米μｍ重　量吨ｔ１ｔ＝１００…     

硒增强雏鸡对IBD抵抗力机制的细胞免疫研究

为了解硒对雏鸡传染性法氏囊病（ＩＢＤ）抵抗大的影响及其细胞免疫机制，自１日龄起给雏鸡分别饲喂基础（含硒０．０８６ｍｇ／ｋｇ）、补硒０．３ｍｇ／ｋｇ和０．６ｍｇ／ｋｇ的不同日粮，于４９日龄采用微量全血培养￣３Ｈ－ＴｄＲ掺入法测定其中自然发生ＩＢＤ后第１０天和正常对照雏鸡的Ｔ淋巴细胞转化率，并计算ＩＢＤ鸡死亡率。结果，两补硒组ＩＢＤ雏鸡死亡率显著低于基础日粮组ＩＢＤ雏鸡（Ｐ＜０．０１）；ＩＢＤ明显抑制雏鸡Ｔ淋巴细胞转化率（Ｐ＜０．０５；Ｐ＜０．０１）；补硒的正常对照雏鸡和ＩＢＤ雏鸡Ｔ淋巴细胞转化率分别高于各自基础日粮雏鸡（Ｐ＜０．０５；Ｐ＜０．０１）。结果显示补硒可提高雏鸡细胞免疫功能，从而增强雏鸡对ＩＢＤ抵抗力，降低雏鸡死亡率。     

不同铜源及水平的日粮对产蛋鸡生产性能及蛋品质的影响

用６８周龄海赛克斯蛋鸡,研究玉米－大豆粕－棉仁粕型日粮中添加５水硫酸铜（ＣｕＳＯ４．５Ｈ２Ｏ）形式的铜６ｍｇ／ｋｇ、３０ｍｇ／ｋｇ、６０ｍｇ／ｋｇ、１２５ｍｇ／ｋ和柠檬酸铜（ＣｕＣｉｔ）形式的铜６ｍｇ／ｋｇ、３０ｍｇ／ｋｇ、６０ｍｇ／ｋｇ试验结果表明：与对照组经（含铜６．４ｍｇ／ｋｇ）,日粮中添加６ｍｇ／ｋｇＣｕ（硫酸铜）时耗料最低,蛋壳厚度最大,且随着添加量的增加蛋壳厚度变薄;日粮中添加３０ｍｇ／ｋｇＣｕ（硫酸铜）时产蛋率最高,料蛋比最低,蛋壳强度最大,日粮中添加不同铜源及水平对蛋黄铜含量的影响不大（Ｐ〉０．０５）。与对照组相比,日粮中添加１２５ｍｇ／ｋｇＣｕ（硫酸铜）时肝脏铜水平明显升高（Ｐ〈０．０５）,但各添加组之间的差异不显著（Ｐ〉０．０５）。随着日粮中铜添加水平的提高,蛋黄和肝脏胆固醇水平显著降低（Ｐ     

不同锰源及锰水平对雏鸭肝脏脂肪沉积的影响

选用１日龄北京雏鸭３００只，研究不同锰源及其锰添加水平对雏鸭肝脏脂肪沉积和肝锰含量的影响。试验１随机分为７组，每组３０只试鸭，在基础饲粮中（含Ｍｎ１９ｍｇ／ｋｇ），钙源及锰添加水平依次为４５、８５、１３５ｍｇ／ｋｇ（试剂级ＭｎＳＯ＿４·Ｈ＿２Ｏ或ＭｎＣＯ＿３）。试验２随机分４组，每组３０只试鸭，在基础饲粮上（含Ｍｎ１９ｍｇ／ｋｇ），补锰水平依次为０、１１０、１０００、３５００ｍｇ／ｋｇ（试剂级ＭｎＳＯ＿４·Ｈ＿２Ｏ），试验３周。结果为：锰源不影响雏鸭肝脏脂肪沉积，肝锰含量和千克活体肝重（Ｐ＞０．０５），锰缺乏（含Ｍｎ１９ｍｇ／ｋｇ）或锰过量（补Ｍｎ３５００ｍｇ／ｋｇ）均影响雏鸭肝脏脂肪沉积和肝锰含量变化（Ｐ＜０．０５或Ｐ＜０．０１）。综合试验结果为：如以肝锰变化作为机体锰营养状况评定指标，则饲粮锰适宜添加量为８５～１３５ｍｇ／ｋｇ。     

日粮铜水平对肉仔鸡生长性能和免疫功能影响的研究

１ 日龄艾维茵肉仔鸡１２０ 只,随机分组,自由采食以葡萄糖－ 大豆分离蛋白为主要原料的半纯合日粮,日粮中分别添加 ０、１１ 和４４０ｍ ｇ／ｋｇ 铜,饮用去离子水,分别于 １ 日龄皮下接种 Ｈ Ｖ Ｔ 冻干苗、７ 和１４ 日龄滴鼻接种 Ｌａｓｏｔａ 系冻干苗。试验结果表明,日粮中０ 或４４０ｍ ｇ／ｋｇ 铜添加组与１１ｍ ｇ／ｋｇ 铜添加组相比：１９、４３ 日龄体重小（ Ｐ＜ ００５）,０ｍ ｇ／ｋｇ 铜添加组０～４３ 日龄单位增重料耗显著高于１１ｍ ｇ／ｋｇ 铜添加组（ Ｐ＜ ００５）;胸腺、法氏囊和脾脏不同程度地萎缩（ Ｐ＜ ００５）,显微分析０ｍ ｇ／ｋｇ 铜添加组胸腺、脾脏、法氏囊、盲肠扁桃体和哈德氏腺发现,淋巴细胞减少且分布疏松,胸腺淋巴细胞膜和核膜不清晰; Ｔ、 Ｂ淋巴细胞对丝裂原的反应性降低（ Ｐ＜ ００５）;血清中 Ｎ Ｄ Ｖ、 Ｍ Ｄ Ｖ 抗体 Ｅ Ｌ Ｉ Ｓ Ａ 效价降低（ Ｐ＜ ００５）,说明铜对维持机体免疫功能状态必不可少。     

牛奶增锌研究

将锌剂ＰＺ按稀元素２，１２，２２，３２ｍｇ／ｋｇ４个水平加入产奶牛日粮中混匀喂牛，牛奶增锌效果极显著（Ｐ〈０．０１），并在正试期的第２阶段均有一增锌高峰期，其后奶锌有基本稳定，对照组，试验组奶锌平均含量分别为３．７３和１３．３０～１６．４８μｇ／ｍＬ。与对照组相比，试验组增幅为２５６．０％～３４２．０％以添加锌元素１２ｍｇ／ｋｇ最佳，各组奶牛生产性能和牛奶质量均无显著性变化（Ｐ〉０．０５）。     

0～4周龄肉仔鸡不同锰源锰需要量的研究

试验将３６０只１日龄ＡＡ（ＡｒｂｏｒＡｃｒｅ）肉鸡公雏随机分为添加锰０ｍｇ／ｋｇ,硫酸锰（ＭｎＳＯ４．Ｈ２Ｏ,下同）６０ｍｇ／ｋｇ,１２０ｍｇ／ｋｇ,１５０ｍｇ／ｋｇ和蛋氨酸锰（Ｍｅｔ－Ｍｎ,下同）４０ｍｇ／ｋｇ,６０ｍｇ／ｋｇ,６个组,６个组基础日粮组成及日粮营养水平相同。试验期为４周。结果表明,所有添加锰组体增重均均显著高于不加锰组（Ｐ〈０．０１）,添加锰６０ｍｇ／ｋｇＭｅｔ－Ｍｎ体增重显著高     

新型预混料对奶牛酒精阳性乳防治作用的研究

为了验证针对酒精阳性乳（alcohol positive milk,AMP）发病机理制作的新型预混料对奶牛酒精阳性乳的防治效果,本研究设计了试验1和试验2：在试验1中,根据泌乳天数、酒精阳性乳程度,采用完全随机区组方法将100头荷斯坦泌乳后期牛分为对照组、低剂量（LDG）、中剂量（MDG）和高剂量组（HDG）,每组5个重复,每个重复5头牛,各组在日粮中依次添加0、50、100和150 g/（头·d）新型预混料,试验期26 d,3 d为1个采样周期;在试验2中,按照试验1的分组方法,将370头荷斯坦泌乳后期奶牛分为对照组和试验组,每组185头,在日粮中依次添加0和100 g/（头·d）新型预混料,试验期35 d,每5 d为1个采样周期。将奶样与等量的75%中性酒精混合,通过观察奶样状态判断酒精阳性乳发生程度。试验1结果表明,与对照组相比,在日粮中添加50 g/（头·d）新型预混料对酒精阳性乳的发生率有一定的影响（P>0.05）;日粮中添加100和150 g/（头·d）新型预混料能显著降低酒精阳性乳发生率（P<0.05）,尤其对降低强阳性酒精阳性乳发生率效果极显著（P<0.01）,但两组之间差异不显著（P>0.05）。试验2结果表明,到试验结束时,日粮中添加100 g/（头·d）新型预混料可使酒精阳性乳总发生率降低75.73%,强阳性酒精阳性乳发生率降低90.82%。以上结果表明,新型预混料能有效防治奶牛酒精阳性乳的发生,且日粮中新型预混料的最佳添加量是100 g/（头·d）。     

Phosphorus supplementation of lactating dairy cattle on a Northland farm

Forty-eight Friesian or Friesian-X factory supply dairy cows were divided into two groups. Group 1 received a supplement of sodiumtripolyphosphate (TPP, 25g P, 25g Na/cow/day), and group 2 a supplement of sodium chloride (25g Na/cow/day). Supplementation began at peak lactation, when the mean serum inorganic phosphorus (Pi) of all cows was 1.13 mmol/l. After four weeks, group 2 changed from NaCl to dicalcium phosphate supplementation (25g P/cow/day). Serum Pi and yields of milk, butterfat and protein were measured before, during and after supplementation. Pasture availability was assessed and P and Ca contents in pasture and the Pi content in milk were also determined. Supplementation raised serum Pi from 1.30 mmol/l (NaCI) to 1.42 mmol/l (TPP, P<0.05) but when dicalcium phosphate replaced NaCl the difference between groups disappeared (P>0.05). P supplementation had no effect on any milk parameter. Pre-grazing pasture mass above estimated grazing height averaged 2260 kg DM and contained >or=0.39 per cent P. It is concluded that a herd mean serum Pi concentration of around 1.2-1.3 mmol/l imposes no limitation to dairy production around the period of peak lactation of grazing dairy cattle.     

Association of increased serum acute‐phase protein concentrations with reproductive performance in dairy cows with postpartum metritis

Background: It is known that quantification of bovine acute‐phase proteins could routinely provide early diagnostic and prognostic information for monitoring herd health status. Objective: The aim of this study was to test the hypothesis that haptoglobin (Hp) and serum amyloid A (SAA) have the potential for indicating uterine infection, mainly due to subclinical endometritis, which can seriously influence the reproductive performance in dairy cows. Methods: A total of 264 serum samples were collected from 24 Holstein dairy cows at defined intervals from 1 week prepartum to 6 months postpartum. Clinically healthy animals (Group 1, n=6) were compared with 24 animals having acute puerperal metritis (Group 2, n=18) and with concentrations obtained from healthy heifers (baseline values, n=10). The concentrations of serum Hp and SAA were measured using a hemoglobin‐binding assay and Western blot analysis, respectively. Reproductive performance was assessed as the number of days open and the conception rate at the end of the study. Results: Upper cut‐off values for Hp and SAA concentrations in heifers were 130.9 μg/L and 51.9 μg/mL, respectively. Hp concentrations in Group 2 were significantly higher than those in Group 1 at all time points (P<.001). Additionally, among the successfully pregnant animals, the number of days open was significantly higher in 6 cows with Hp >130.9 μg/mL (median=316 days) than in 11 cows with Hp ≤130.9 μg/mL (median=120 days) (P=.0024). Conclusions: Serum Hp and SAA concentrations can be used to recognize uterine infection in postpartum cows. The association between elevated Hp values and number of days open suggests Hp may also be a useful indicator of poor prognosis for reproductive performance.     

奶牛血清孕酮和总胆固醇水平与超数排卵效果的关系

为了研究血清中若干生化指标与母牛超数排卵的关系。在性周期中期第10天或11天超排处理之前颈静脉采血,用以测定血清中孕酮、总胆固醇等指标的水平,而后用FSH进行超排处理。输精后第7天左右采用非手术采卵,并通过形态学检查对胚胎进行鉴定。根据可用胚胎数将供体母牛分为A组(可用胚胎>2枚)和B组(可用胚胎≤2枚),并比较两组孕酮、总胆固醇等指标的水平。结果表明:周期中期血清孕酮水平在3.0ng/ml以上对于预选供体母牛是有效的。血清总胆固醇水平与可用胚胎数的相关系数r=0.6079(n=19;P<0.01),周期中期血清总胆固醇水平高于140mg/dl似乎可以做为预选供体牛较好的参数。     

日粮中添加酵母或酵母培养物对奶牛生产性能的影响

试验旨在研究日粮中添加酵母或酵母代谢物产品对奶牛生产性能的影响。选择70 头中国荷斯坦泌乳奶牛,按产奶量、泌乳天数和胎次等情况配对分成7组,每组10 头,其中试验1组为对照组,其余6组为试验组。对照组饲喂基础日粮,该日粮主要包含20 kg青贮、3 kg干草、2 kg苜蓿干草和9 kg泌乳期奶牛精料补充料。试验组在饲喂基础日粮的基础上再分别添加60 g益生素酵母1、50 g益生素酵母2、10 g益生素酵母3、10 g益生素酵母4、15 g益生素酵母5和15 g益生素酵母6。试验期为50 d,其中预试期10 d,正试期40 d。结果表明,不同的酵母或酵母代谢物产品对奶牛产奶量和奶成分有不同程度的影响,添加益生素酵母2试验组奶牛的产奶量与对照组相比增加显著( P<0.05)。不同的酵母及酵母代谢物产品对牛乳成分也有不同程度的影响,益生素酵母1、益生素酵母2和益生素酵母3显著提高了牛奶中乳脂含量(P<0.05);益生素酵母4显著提高了牛奶中蛋白含量(P<0.05);不同酵母或酵母代谢物产品对牛奶中干物质含量无显著影响;在体细胞数方面,添加益生素酵母2、益生素酵母3和益生素酵母4的试验组牛奶中体细胞数有一定的降低,但差异不显著(P>0.05)。因此,本试验证明饲料中添加酵母及酵母代谢物能提高奶牛的生产性能。     

我国规模牛场奶牛个体生鲜乳体细胞数水平及影响因素探析

本研究旨在探析我国规模奶牛场奶牛个体生鲜乳体细胞数（SCC）的水平、分布和影响因素。利用SAS9.0的GLM模型,统计分析覆盖16个省（市、区）,33个规模奶牛场,23 351头中国荷斯坦牛,从2007年至2009年连续3年的225 775条奶牛个体生鲜乳SCC检测记录。结果表明：奶牛个体生鲜乳SCC的总体均值为48×104cell/mL,标准差为117×104cell/mL,个体生鲜乳SCC波动范围较大;其中,77.9%的奶牛个体,其生鲜乳SCC小于50×104cell/mL,对群体混合样生鲜乳SCC的影响系数为0.26;11.3%的奶牛个体,其生鲜乳SCC介于50×104～100×104cell/mL之间,乳房处于隐性感染状态,对群体混合样生鲜乳SCC的影响系数为0.16;10.8%的奶牛个体,生鲜乳SCC大于100×104cell/mL,理论上乳房处于临床感染状态,对群体混合样生鲜乳SCC的影响系数为0.58。奶牛个体生鲜乳体细胞数评分（SCS）呈正态分布,与奶牛个体因素（产奶量、乳脂率、乳蛋白含量、胎次和泌乳阶段）和环境因素（泌乳月份、泌乳季节）差异极显著（P〈0.01）,与奶牛养殖区域、奶牛场差异不显著（P〉0.05）。我国规模奶牛场奶牛个体生鲜乳SCC主要在50×104cell/mL以下,依据影响参数能实现对生鲜乳SCC水平的调控。     

Phosphorus supplementation of lactating dairy cattle on a Northland farm

Abstract

Forty-eight Friesian or Friesian-X factory supply dairy cows were divided into two groups. Group 1 received a supplement of sodiumtripolyphosphate (TPP, 25g P, 25g Na/cow/day), and group 2 a supplement of sodium chloride (25g Na/cow/day). Supplementation began at peak lactation, when the mean serum inorganic phosphorus (Pi) of all cows was 1.13 mmol/l. After four weeks, group 2 changed from NaCl to dicalcium phosphate supplementation (25g P/cow/day). Serum Pi and yields of milk, butterfat and protein were measured before, during and after supplementation. Pasture availability was assessed and P and Ca contents in pasture and the Pi content in milk were also determined. Supplementation raised serum Pi from 1.30 mmol/l (NaCI) to 1.42 mmol/l (TPP, P<0.05) but when dicalcium phosphate replaced NaCl the difference between groups disappeared (P>0.05). P supplementation had no effect on any milk parameter. Pre-grazing pasture mass above estimated grazing height averaged 2260 kg DM and contained ?0.39 per cent P. It is concluded that a herd mean serum Pi concentration of around 1.2–1.3 mmol/l imposes no limitation to dairy production around the period of peak lactation of grazing dairy cattle.     

Management, feeding, production, reproduction and udder health on organic and conventional Swiss dairy farms

Organic dairy farms (OP; n=60) and conventional dairy farms (integrated production, IP; n=60), matched in size, location, and agricultural zone (altitude), were studied for possible differences in management, feeding, production, reproduction and udder health. OP and IP farms were similar in size (17.7 and 16.9 ha), milk quota (65900 and 70,000 kg/year), cow number (14 and 15), cow age (5.3 and 5.2 years), housing of cows of the Simmental x Red Holstein or Holstein breeds (87 and 75%; 45 and 60%), but differed significantly with respect to loose housing systems (18 and 7%), outside paddocks (98 and 75%), energy-corrected 305-d milk yield (5,695 and 6,059 kg), milk protein content (31.8 and 32.7 g/kg), use of bucket milking systems (73 and 33%), observance of regular (12-h) milking intervals (47 and 68%), routine application of the California-Mastitis-Test (10 and 28%), teat dipping after milking (25 and 43%) and blanket dry cow treatments (0 and 45%). Milk somatic cell counts on OP and IP farms (119 000 and 117,000/mL) and reproduction data were similar and there were no significant differences between OP and IP farms as concerns available feeds, planning and management of feeding. Alternative veterinary treatments were used more often on OP than IP farms (55 and 17%). Main causes for cow replacements on OP and IP farms were fertility disorders (both 45%), age (40 and 42%), sale (30 and 37%) and udder health (35 and 13%).Between OP and IP Swiss dairy farms thus relatively few larger differences were found.     

酶制剂对泌乳前期奶牛产奶量和乳成分的影响

选择年龄、胎次、产奶量和泌乳时间相近的30头泌乳前期荷斯坦牛,随机分为3组(试验Ⅰ组、Ⅱ组和对照组),每组10头。在试验组精料补充料中添加300g/t和600g/t的非淀粉多糖酶制剂,研究其对奶牛产奶量和乳成分的影响。结果表明,与对照组相比,试验Ⅰ、Ⅱ组奶牛产奶量分别提高了1.18kg/d和1.23kg/d,乳脂率分别提高了0.03和0.39个百分点,乳蛋白率分别提高了0.01和0.05个百分点,体细胞数分别下降15.86万个/mL和14.63万个/mL,但差异均不显著(P>0.05);在泌乳前期的奶牛日粮中添加外源非淀粉多糖酶制剂具有促进奶牛泌乳、改善乳成分的趋势。     

Effects of Ethanol on Synthesis of Prostaglandin F2α in Bovine Females

Ethanol stimulates the production of prostaglandins in many species. The purpose of this study was to verify the effect of ethanol on the production of prostaglandin F2α (PGF2α) and luteolysis in bovine females. In the first experiment, Holstein cows at day 17 of the oestrous cycle were treated with 100% ethanol (0.05 ml/kg of body weight, IV; n = 5), saline (0.05 ml/kg of body weight, IV; n = 4) or synthetic prostaglandin (150 μg of D‐cloprostenol/cow, IM; n = 4). The plasma concentrations of 13, 14‐dihydro‐15‐keto PGF2α (PGFM; the main metabolite of PGF2α measured in the peripheral blood) were assessed by radioimmunoassay (RIA). There was an acute release of PGFM in response to ethanol comparing to other treatments (p ≤ 0.05). However, only cows treated with PGF2α underwent luteolysis. In the second experiment, endometrial explants of cross‐bred beef cows (n = 4) slaughtered at day 17 of the oestrous cycle were cultured for 4 h. During the last 3 h, the explants were cultured with medium supplemented with 0, 0.1, 1, 10 or 100 μl of 100% ethanol/ml. Medium samples were collected at hours 1 and 4 and concentrations of PGF2α were measured by RIA. Ethanol did not induce PGF2α production by the endometrium. In conclusion, ethanol does not cause luteolysis in cows because it stimulates production of PGF2α in extra‐endometrial tissues.