贵州胚胎工程技术研究及示范应用效果

21世纪以来,贵州开展了牛同期发情、超数排卵、胚胎分割、早期胚胎性别鉴定、胚胎移植等试验及其示范应用。研究表明:结合使用孕酮阴道栓和氯前列烯醇进行同期发情,受体合格率分别为50.12%(423/840)和37.82%(247/653),同期发情率分别为81.09%(343/423)和65.58%(162/247),受体妊娠率分别为51.52%(136/268)和18.57%(26/140),胚胎移植总效率分别为16.36%和3.98%,前者均极显著高于后者(P<0.01);促卵泡素法处理供体平均获得可用胚胎数4·8枚(43/9),促卵泡素 雌二醇法处理供体获可用胚9.8枚(117/12),差异极显著(P<0.01),说明促卵泡素和雌二醇结合使用进行超排,可改善牛的超排效果,显著增加可用胚胎数;8、10月份移植妊娠率分别为40.34%(48/119)、45.41%(84/185),均高于12月份的24.80%(26/105),且差异显著(P<0.05),可见,由于天气较寒冷且受体牛的饲草料不足,将严重影响胚胎移植妊娠率;8月份供体牛超数排卵的平均采胚数(8.40枚/头)及平均可用胚数均高于12月份的(5.81枚/头),其中平均可用胚数两者差异显著(P<0.05),在天气较寒冷的月份对供体牛进行超数排卵将会影响超排效果;移植双半胚和整胚的妊娠率分别为54.20%(13/24)和27.30%(6/22),前者为后者的2倍,表明在生产实践中通过胚胎分割不但可以成倍增加胚胎的数量,而且可以提高移植后的妊娠率;性别鉴定雌性胚胎冻胚的移植妊娠率40%(40/100),略低于常规冻胚的43.55%(27/62),但差异不显著(P>0.05);2003-2004年全省共移植牛胚胎1208枚,妊娠463头,移植妊娠率37.58%(454/1208)。初步建成了牛良种繁育体系,成效明显。     

纯种和牛快速扩繁关键技术研究

为达到快速扩繁纯种和牛的目的,试验从供体牛高强度超数排卵、胚胎性别鉴定及不同品种受体牛移植对产犊、妊娠期和犊牛初生重的影响进行研究。结果表明,纯种和牛连续超排9次,每次间隔30 d,第2次头均回收胚数22.78枚,显著高于第5~9次结果（P< 0.05）,其余各组之间无显著差异（P> 0.05）;第1~3次头均可用胚数分别为8.67、13.78、8.56枚,组间无显著差异（P> 0.05）,第2次头均可用胚数显著高于第4~9次头均可用胚数（P< 0.05）,极显著高于第7、9次头均可用胚数（P< 0.01）。性别鉴定胚胎和常规胚胎移植妊娠率和产犊率差异均不显著（P> 0.05）,性别鉴定胚胎的母犊率为95.56%。西门塔尔杂交牛受体产犊率高于和牛杂交牛、荷斯坦奶牛受体,但差异不显著（P> 0.05）。和牛杂交牛受体妊娠期极显著高于西门塔尔杂交牛和荷斯坦奶牛受体（P< 0.01）,西门塔尔杂交牛和荷斯坦奶牛之间差异不显著（P> 0.05）;西门塔尔杂交牛受体所产和牛母犊初生重显著高于和牛杂交牛受体（P< 0.05）,极显著高于荷斯坦奶牛受体（P< 0.01）,3个品种受体牛产和牛公犊初生重之间差异不显著（P> 0.05）;同一品种受体牛其产公、母犊牛的妊娠期及初生重均相近。     

波尔山羊胚胎移植影响因素的研究

试验就胚胎的发育阶段、胚胎保存时间及移植胚胎数等因素对胚胎移植效果的影响情况进行了研究。结果表明,胚胎发育日龄对受体妊娠率没有显著影响(P>0.05),但移植8~16细胞的胚胎的妊娠率略高于2~4细胞(58.49%vs 61.47%)。人员不是影响受体妊娠率的主要因素。胚胎在体外保存0~120min对妊娠率没有显著影响,但以在体外保存0~30 min内移植的妊娠率最高(65.61%)。黄体与移植胚胎的相对位置对受体的妊娠率没有显著影响(P>0.05),但移植双胚的受体的妊娠率较移植单胚高(61.76%vs 45.17%)。同时,试验统计了经胚胎移植产生的羔羊和自然繁殖羔羊之间的差异,发现经胚胎移植产生的波尔山羊母羔的初生重极显著地高于自然繁殖的母羔(P<0.01),但公羔间的初生重以及公、母羔间的体高、体长、胸围、死亡率和性别比例与自然繁殖羔羊差异不显著(P>0.05)。     

影响受体牛冷冻移植胚胎效果的主要因素

试验研究影响受体牛移植冷冻胚胎效果的主要因素,目的是解决胚胎移植产业化中容易出现的技术问题,以提高牛胚胎移植妊娠率。在季节、饲养管理、同期发情处理和胚胎移植技术以及环境条件等基本相同的情况下,结果表明:西门塔尔杂交牛的移植利用率和移植妊娠率高于黄牛杂交牛和黑白花奶牛,但各组间无显著性差异(P>0.05);2～6周岁的受体牛移植利用率和移植妊娠率高于7周岁以上和2周岁以下的受体牛,但各组间无显著性差异(P>0.05);经产1～3胎受体牛移植利用率显著高于4胎以上的受体牛(P<0.05),而移植妊娠率则无显著性差异(P>0.05);体况上等与中等的受体牛移植利用率和移植妊娠率无显著性差异(P>0.05);同期发情处理时卵巢处于黄体期的移植利用率显著高于卵泡期,差异极显著(P<0.01);左侧卵巢有黄体的子宫角胚胎移植妊娠率显著高于右侧(P<0.05);胚龄对胚胎移植妊娠率高低依次为早期囊胚、桑椹胚和囊胚,但无显著性差异(P>0.05)。     

解冻后胚胎质量对移植妊娠率的影响

研究分析了胚胎质量等级对胚移妊娠率的影响,用于移植的冷冻性控胚胎由加拿大进口,胚胎移植的受体为鲁西黄牛和西门塔尔牛。分析结果显示:解冻后的胚胎等级对受体牛的妊娠率有一定程度的影响,其中A级胚胎的受体妊娠率较C级胚胎的受体妊娠率高15%左右,差异显著(P<0.05);另外,虽然受体母牛品种对移植受胎率也有一定程度的影响,但没有显著差异(P>0.05)。     

波尔山羊胚胎移植影响因素的研究

试验就胚胎的发育阶段、胚胎保存时间及移植胚胎数等因素对胚胎移植效果的影响情况进行了研究.结果表明,胚胎发育日龄对受体妊娠率没有显著影响(P＞0.05),但移植8～16细胞的胚胎的妊娠率略高于2～4细胞(58.49% vs 61.47%).人员不是影响受体妊娠率的主要因素.胚胎在体外保存0～120 min对妊娠率没有显著影响,但以在体外保存0～30 min内移植的妊娠率最高(65.61%).黄体与移植胚胎的相对位置对受体的妊娠率没有显著影响(P＞0.05),但移植双胚的受体的妊娠率较移植单胚高(61.76% vs 45.17%).同时,试验统计了经胚胎移植产生的羔羊和自然繁殖羔羊之间的差异,发现经胚胎移植产生的波尔山羊母羔的初生重极显著地高于自然繁殖的母羔(P＜0.01),但公羔间的初生重以及公、母羔间的体高、体长、胸围、死亡率和性别比例与自然繁殖羔羊差异不显著(P＞0.05).     

黑萨福克和杜泊羊新鲜和冷冻胚胎移植效率的研究

为提高优质肉用种用绵羊胚胎移植的效率,试验选取76只黑萨福克羊和27只杜泊羊作为供体,采用"CIDR+FSH+PMSG"法进行超数排卵处理。选取384只小尾寒羊为受体,采用"CIDR+PMSG"法进行同期发情处理,以探索供体胚胎发育阶段、胚胎冷冻处理、胚胎体外停留时间以及移植给受体时移植侧黄体数量等因素对胚胎移植妊娠率的影响。结果表明:移植新鲜囊胚的妊娠率极显著高于桑椹胚(P0.01);冷冻/解冻囊胚移植妊娠率极显著低于新鲜囊胚(P0.01),而冷冻/解冻桑椹胚移植妊娠率与新鲜桑椹胚无显著差异(P0.05);此外,移植桑椹胚时,移植侧有1个黄体的受体妊娠率极显著低于有2~3个黄体受体妊娠率(P0.01),但移植囊胚时两者间差异不显著(P0.05)。综上可知,子宫角移植桑椹胚和囊胚时,移植新鲜囊胚、移植冷冻桑椹胚效率较高;将新鲜桑椹胚移植给移植侧有2~3个黄体受体效果好于1个黄体受体。     

提高波尔山羊胚胎移植妊娠率研究

本文就波尔山羊胚胎质量、胚胎发育阶段、胚胎数量、受体卵巢黄体数、受体注射LRH-A3、供、受体发情同期化程度以及胚胎移植的方向等因素与受体移植妊娠率的关系进行了研究。结果表明:移植囊胚较移植1枚B级桑椹胚妊娠率高;A级桑椹胚妊娠率显著高于移植1枚B级桑椹胚(P<0.05);移植2枚B级桑椹胚妊娠率比移植1枚B级桑椹胚的高39.4%(P<0.05);受体注射LRH-A3有助于提高妊娠率;供、受体发情同步差在48 h以上组妊娠率显著低于0~24 h和24~48 h组(P<0.05);向子宫角前端方向的移植妊娠率比向子宫角基部方向的高12.2个百分点。     

牛胚胎日龄与移植时间对妊娠率的影响

探讨胚胎移植过程中受体与胚胎日龄的最佳结合点.本文对接受移植受体牛的发情天数与胚龄进行了研究,选取北京奶牛中心的3种不同胚龄的A级胚胎分成两组进行移植,A组采用随机移植方案,B组采用同步移植方案,结果B组胚胎妊娠率(61.11%)高于A组胚胎妊娠率(25.81%),两组之间存在显著性差异(P<0.05).表明在胚胎移植中同步移植的效果好于随机移植.     

波尔山羊供体和受体异地饲养鲜胚移植研究

为了进一步扩大良种波尔山羊的推广,提高胚胎移植效率,该文就饲养在不同牧场间的供体和受体实现鲜胚移植进行了系统研究,得到了以下结果:①洪体运输1h、2～3 h、＞4h、0h(对照)收集胚胎,分别得到可用胚胎数为15.8枚±4.3枚、13.0枚±5.7枚、13.8枚±6.6枚和14.2枚±6.3枚,不同运输时间回收可用胚胎数之间无显著性差异(P＞0.05).回收可用胚胎移植后,受体妊娠率分别为71.6％、67.6％、76.7％和80.7％,胚胎成羔率分别为74.1％、67.2％、69.9％和71.5％,供体不同运输时间回收胚胎移植妊娠率和胚胎成羔率无显著差异(P＞0.05).②胚胎在20℃,36.5℃和38.5℃运输2h后移植,受体妊娠率分别为42.0％、64.5％和66.7％,胚胎成羔率分别为41.7％、63.6％和66.7％.20℃运输胚胎受体妊娠率和胚胎成羔率显著低于36.5℃和38.5℃下运输胚胎(P＜0.01);胚胎在36.5℃分别运输0.5 h、1h、2h后移植,受体妊娠率分别为72.5 ％68.7％和64.9％,胚胎成羔率分别为69.1％、67.8％和63.0％,受体妊娠率和胚胎成羔率之间无显著性差异(P＞0.05).③受体在手术前2～4h通过卡车运输到另一畜牧场,运输时间分别为0.5 h、1h、≥2h,胚胎移植后受体妊娠率分别为61.2％、49.6％和42.0％.随着受体运输时间的延长,受体妊娠率呈下降趋势,运输时间超过2h的妊娠率显著低于运输0.5 h的妊娠率(P＜0.05).胚胎成羔率分别为60.9％、45.6％和32.0％,随着受体运输时间的延长,胚胎成羔率显著下降(P＜0.05或P＜0.01).从以上研究得出以下结论:山羊供体和受体饲养在不同饲养场,欲进行鲜胚移植,选择供体运输是最好的方法,其次为胚胎运输后移植.受体运输对胚胎移植效果(即受体妊娠率及胚胎成羔率)均有不利影响,不宜在生产中采用.     

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.     

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.     

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     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in