奶牛产后首次发情的变化规律及其影响因素

奶牛产后恢复发情时间的早晚是繁殖方面一个很重要的问题。它与产后奶牛的受胎率、产犊间隔及终生繁殖效率均有密切关系。为探讨黑白花奶牛     

奶牛产后乏情病因的调查分析

奶牛产后期是指从奶牛胎衣排出后开始到生殖器恢复到正常状态为止.在此期间,奶牛没有明显的发情表现、卵巢无周期性机能活动,称为产后乏情.为了能够及时给产后的奶牛进行配种,缩短产犊间隔,要特别注意奶牛产后的第一次发情.奶牛产犊后,需要经过卵巢功能、子宫形态、子宫和内分泌机能等恢复过程,才会出现发情.奶牛产犊后第一次发情时间,通常在产后20～60 d.如果产后90 d还没有出现发情,就视为产后乏情.在奶牛生产实践中,其经济效益主要受奶牛产犊和产奶量的影响,要提高奶牛生产的经济效益,就是缩短产犊间隔.为了能达到奶牛1年1胎的目的,就要在产后75～85 d范围内受胎,不能超过90 d.一般认为在产后40～60 d发情配种最为适宜.     

产犊季节和胎次对荷斯坦牛部分繁殖指标的影响

为了研究不同产犊季节和胎次对荷斯坦牛部分繁殖指标的影响,为长江中下游地区荷斯坦牛合理安排配种时间提供科学依据.本试验利用海丰奶牛场引进的澳系荷斯坦牛的繁殖指标数据,分析了产犊季节和不同胎次对部分繁殖指标的影响.结果显示,产犊季节对产后第一次发情泌乳天数、配种指数、产后受孕天数以及产犊间隔等繁殖指标的影响达到极显著水平(P＜0.01).胎次对发情泌乳天数、产后受孕天数以及产犊间隔等繁殖指标的影响也达到极显著水平(P＜0.01).在本研究中,秋季产犊的奶牛繁殖指标最佳.此外,头胎产犊奶牛的繁殖性能在各胎次中最好,该结果对同类地区荷斯坦牛繁殖管理有很好的指导作用.     

奶牛产后常见繁殖疾病防控

随着奶牛行业发展,牧场走规模化、集约化道路,追求高产量同时,都关注奶牛产后是否能尽快配种并受孕,从而缩短产犊间隔,减少饲养成本。新产牛护理中子宫保健是指奶牛产后子宫恢复到未孕时形态和功能的生理过程。产后子宫保健的过程和子宫恢复的状态决定奶牛产后第1次发情的受胎率,即首配受胎率。奶牛产后如果子宫复旧不全,会多发繁殖疾病,严重影响奶牛首配受胎率。由于产后发情配种未怀孕则导致受孕时间推迟,产犊间隔增加,意味着空怀饲养天数增加和牧场经济效益降低,所以牧场应时刻关注奶牛产后子宫护理工作及常见繁殖疾病的防控。     

影响奶牛产后繁殖机能恢复的因素

健康的繁殖性能是奶牛泌乳和生产的基础,直接影响到奶牛养殖经济效益和奶业的可持续发展.奶牛产后繁殖机能的恢复,即奶牛产后正常发情与配种.它与奶牛产后的情期受胎率、产犊间隔及终身繁殖效率均关系密切,是评判奶牛繁殖力的重要指标.本文对奶牛产后繁殖机能恢复与品种、营养水平、胎次与胎儿、产奶量、季节与环境、疾病等因素的关系作简要综述.     

奶牛不发情的诊断及治疗

在生产中,奶牛不发情或发情延迟的现象经常出现,不仅使产犊间隔延长,还使奶牛的繁殖率大大降低.繁殖人员对14月龄以上的后备牛不见发情症状的和产后60d不发情的母牛,应及时进行分析和生殖检查,并从改善饲养管理和应用生殖激素着手,使其恢复性周期.     

利用GnRH和PGF_(2α)提高群体奶牛繁殖效率

<正>现阶段奶牛养殖过程中,由于营养和饲养管理等原因,普遍存在奶牛产后发情延迟和奶牛隐性发情的情况,这已成为奶牛繁殖的一大障碍,如处理不好会大大增加奶牛空腹天数,极大影响奶牛养殖的效益。发情鉴定在规模化奶牛养殖中是一个难题,容易因发情鉴定不及时而错过配种期,增加空腹天数,延长产犊间隔,降低繁殖效率。使用同期发情、同期排卵和定时输精技术可以有效地克服这一缺点。在兽医临床实     

奶牛不发情的诊断及治疗

在生产中,奶牛不发情或发情延迟的现象经常出现,不仅使产犊间隔延长,还使奶牛的繁殖率大大降低。繁殖人员对14月龄以上的后备牛不见发情症状的和产后60d不发情的母牛,应及时进行分析和生殖检查,并从改善饲养管理和应用生殖激素着手,使其恢复性周期。     

延长产犊间隔将影响奶牛产奶量

一些奶农在生产中,往往在奶牛产后72～93天内,由于发情鉴定不准和牛患生殖系统疾病不能及时治愈,造成奶牛不能及时受孕,使产犊间隔超过12个月,进而产奶天数也随之向后推迟,超过305天.有些奶农还错误地认为,只要母牛有奶可产,下一次产犊间隔延长也无妨.他们并没有意识到因产犊间隔延长而造成的隐性损失,利用的恰恰是奶牛泌乳末期的低产时间,而忽视了产犊后的高峰期.据测算,产犊间隔每延长1个月,其产奶量将递减2.5%.产犊间隔越长,损失越大,当间隔时间达到20个月时,比间隔12个月时年经济效益低1660多元.若从低产奶牛与高产奶牛的奶料比考虑,对经济效益的影响更大.     

胎次、犊牛性别和初生重及产犊季节对奶牛繁殖性能的影响

为研究不同胎次、犊牛性别和初生重以及产犊季节对繁殖性能的影响,为奶牛的科学配种与产后护理提供参考,本研究测定了120头荷斯坦奶牛产后第一次发情、配种时间、胎衣排出时间、子宫粘液评分及直肠检查评分等繁殖性能指标,并与奶牛的胎次、犊牛性别和初生重以及产犊季节进行相关性分析。结果表明,4胎及以上奶牛的产后第一次发情时间比前3胎要迟10~18d,其产后子宫粘液评分低0.59~0.79分,直肠检查评分低0.53~0.85分(P0.05);产母犊的奶牛第一次发情时间比产公犊的早3.15d,当犊牛初生重大于45kg时奶牛胎衣排出时间最长(17h);冬季奶牛产后第一次发情时间比其它季节早10~12d(P0.05)。研究认为,不同胎次、犊牛性别和初生重以及产犊季节对奶牛产后的第一次发情时间、胎衣排出时间、子宫粘液和直肠检查评分有显著影响。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein