中国驴品种资源现状及其分子遗传育种研究进展

驴是中国一个古老畜种,对不良环境适应性强,耐粗饲、抗病力强,一直是役、驮、乘、肉、药多用资源之一。但随着农业机械化、运输业快速发展及人民生活水平提高,近些年来驴品种资源整体面临着种质资源退化、种群数量和质量显著下降等问题。本文针对我国驴品种资源概况、保护利用现状、存在问题及其分子遗传育种研究进展进行综述,以期为驴品种资源的保护及开发利用提供参考。     

Pyrantel resistance in two herds of donkey in the UK

Resistance to currently available anthelmintics is a serious phenomenon which is prevalent globally. Cyathostomins are one of the major parasites, and are of primary concern in donkeys. There have been reports of emerging resistance to pyrantel, but the status of pyrantel resistance in donkey populations in the UK is largely unknown. This report investigates pyrantel resistance in two geographically isolated donkey herds in the South West of England. The first herd had suspected pyrantel resistance, with already established resistance to other anthelmintics. In the second herd the efficacy of pyrantel was not suspected at the time the study took place. Faecal Egg Count Reduction Test (FECRT) was carried out, revealing large scale resistance. Eighty one percent of the first herd and 73% of the second herd had a FEC of less than 95% after treatment, and anthelmintic resistance was confirmed using the World Association for the Advancement of Veterinary Parasitology guidelines. These findings indicate that anthelmintic resistance to pyrantel exists in both tested donkey populations and illustrate the continuing development of resistance through different classes of chemotherapeutics.     

Advances in the Research and Application of Artificial Insemination to Equids in China: 1935–2012

China was one of the first countries to use artificial insemination (AI) in equids, and it achieved international recognition for its widespread application of AI to commercial horse breeding. This article reviews the history of equine AI in China. The technique originated from the high demand for horses to be used in agriculture, transportation, and the military. Artificial insemination was identified as an ideal tool for Chinese horse breeding to improve the productivity of native horses, especially during 1950-1970. Presently, AI is still practiced commonly in China, and it includes the use of fresh semen and transported cooled semen. The use of frozen semen has also been resumed to broaden the range of elite Sporthorse stallions and to preserve threatened or endangered native breeds. Accurate prediction of the optimum time for insemination depended mainly on transrectal palpation of the mare's ovaries. In addition to controlled methods of insemination, factors like volume and number of spermatozoa in the inseminate and timing and frequency of insemination were optimized to accomplish high fertility rates in the field. Production of hinnies and mules for agricultural labor and donkeys for meat and hide gelatin stimulated a nationwide upsurge of research into the reproductive physiology of and AI technology in donkeys. In the future, there will be further increases in the use of traditional and modern AI techniques in the breeding of Chinese equids.     

应用RACE技术扩增驴DGAT1基因3′端及序列分析

DGAT1（脂酰辅酶A：二脂酰甘油酰基转移酶）基因是产奶性状的一个重要功能侯选基因。由于通过预测奶牛DGAT1基因序列与马属动物DGAT1基因序列具有98%的同源性,本试验从影响牛产奶性状的DGAT1基因出发,以驴乳腺组织的RNA为模板,按照不同物种DGAT1基因的相似性设计特异引物,运用PCR和3′RACE技术扩增并获得了特异片断,特异片段回收纯化连接到pUCmT Vector载体后,转化到大肠杆菌中并筛选阳性菌落;提取质粒进行测序,结果发现该段序列与预期的目标一致,通过与其他动物同源性比较分析说明已首次克隆到驴DGAT1基因3′端。     

Plasma pharmacokinetics and faecal excretion of ivermectin (Eqvalan paste) and doramectin (Dectomax, 1%) following oral administration in donkeys

Ivermectin (IVM- Eqvalan paste, 1.87%) and doramectin (DRM-Dectomax 1%) were each administered orally to donkeys at 200 microgkg(-1) bodyweight. Blood and faecal samples were collected at predetermined times over 30 days and plasma pharmacokinetics and faecal excretion determined. Maximum plasma concentrations (C(max)) of IVM (23.6 ngml(-1)) and DRM (33.9 ngml(-1)) were obtained at (t(max)) 19.2 and 24h, respectively. The area under the concentration curve (AUC) of DRM (228.9 ngdayml(-1)) was significantly larger than that of IVM (119.3 ngdayml(-1)) and mean residence time (MRT) was 6.5 days for IVM and 9.1days for DRM. The highest (dry weight) faecal concentrations (9.33 microgg(-1) - IVM, 12.12 microgg(-1) - DRM) were detected at 55.9 and 48.0 h, respectively and each compound was detected (0.05 microgg(-1)) in faeces between 11h and 9 days following oral administration in donkeys.     

Digital Agenesia in Martina Franca Donkey Foal: A Case Report

A 4-day-old male Martina Franca donkey foal was evaluated for a forelimb alteration. Clinical examination and radiographs revealed the agenesia of the distal digit. Biochemical parameters were normal, and ultrasonographic evaluation did not identify any relievable organ alteration. Karyotype study revealed an abnormality on chromosome 1. The foal was discharged with a distal limb bandage in which a palmar splint was applied. A poor prognosis for the functionality of the limb was given. In endangered species, such as the Martina Franca donkey, the excessive inbreeding could result in an increase in genetic disorders. These findings shed new light on the possible pathogenesis of the digital dysgenesia. The study of the karyotype could be a useful approach to detect genetic alterations that could or could not be expressed in the animal, especially in endangered species in which a risk of an excessive inbreeding is considerable. These defects should be considered in the choice and selection of the breeders.     

A Cross-Sectional Survey of Foaling-Related Parameters of Jennies (Equus asinus) Under Smallholder Farm Conditions in Northeast China

It is important to assess the reproductive efficiency and improve the reproductive management to promote the donkey population development. The overall foaling-related parameters of jennies under smallholder farm conditions in China were hardly under investigation. A cross-sectional survey of randomly selected 694 smallholder farms was conducted in 40 villages in the north, east, and south areas of Western Liaoning Province and Eastern Inner Mongolia Autonomous Region between March and July, 2017. Foaling-related parameters were assessed such as the mean age at first foaling, foaling rate and foaling interval during 2014–2017. Only two-thirds of the adult jennies foaled during the 3-year survey period and delivered a foal every 1.9 years. The mean age at first foaling was 45.3 months. The lowest incidence of foaling rate was in coincidence with the peak of foaling. The overall mean values for the foaling rate and foaling interval were 75% and 500.5 days, respectively. Significant changes of foaling rates before the age of 15 years and foaling intervals in the first 8 parities were not observed. The results indicate that the jennies could maintain relatively fine foaling-related parameters under smallholder farm conditions in northeast of China. However, the foaling rates hardly remained high during the whole breeding season represented a major loss to the donkey breeding.     

Timed Artificial Insemination by Combining Estrous Behavior Observation With Deslorelin Treatment in Jennies

The purpose of this study was to determine the optimal time for ovulation induction and artificial insemination (AI) based on the relationship between estrous behavior and ovulation in jennies. Thirty-two jennies were teased by one jackass for 1 hour per day during 46 days and estrous behaviors were recorded, while the follicular development and ovulation was examined by ultrasound. Furthermore, another 31 jennies were teased by one jackass as the teasing group (group T), which were injected with Deslorelin at 2 and 4 days after the onset of estrus, and AI was performed at 8 hours after each injection. Moreover, Ultrasound was performed on the follicle development of 23 jennies as the ultrasonography group (group U). Injection with Deslorelin when the follicle diameter ≥ 30 mm, and AI was performed at 8 hours later. The results showed that mouth clapping was the specific estrous behavior of jennies and indicated the beginning of estrus. The mean time for jennies to develop dominant follicles (≥30 mm) after the onset of estrus was 3.5 ± 1.3 days, and the mean time between the onset of estrus and ovulation was 5.1 ± 1.5 days. Estrous behaviors ended 0.5 ± 1.2 days after ovulation. After AI, there were no significant differences in ovulation (96.8% vs. 91.3%) and conception rates (40.0% vs. 38.1%) between group T and U. The optimal breeding time of jennies can be determined by jackass teasing and hastening ovulation by Deslorelin injection.