Performance of Djallonké Sheep under an Extensive System of Production in Faranah,Guinea

A total of 147 ewes, 4 rams and 188 lambs of their progeny of the Djallonké breed of sheep were used to study the factors affecting reproductive and growth traits and the causes of lamb mortality. Data on ewes were collected during a 12-month period, while those on the lambs born to 123 of the ewes were collected until they were 12 months of age. The average fertility and abortion rates were 0.84 and 0.09. The fertility rate increased and the abortion rate decreased with increasing age of the ewes (p<0.05). The number of lambs born per ewe joined, litter weight at birth per ewe joined and litter weight at weaning per ewe joined were 1.28, 3.5 kg and 17 kg, respectively. The average numbers of lambs born per ewe, lambs born alive per ewe, lambs born dead per ewe and lambs per ewe that died between birth and weaning were 1.53, 1.43, 0.03 and 0.3, respectively. The age of the ewes significantly (p<0.05) affected all these traits except the number of dead lambs and the index of fertility (94%). The age of the ewes significantly (p<0.05) affected the birth weight and the weight at 6 and 12 months of age, whereas the lambing season significantly (p<0.05) affected all the growth traits studied. The type of birth was the most important source of variation in body weights of lambs. Sex had no significant (p>0.05) effect on the growth traits studied. The complex `starvation–bad management–light body weight at birth' caused 48% of the lamb mortality between birth and weaning, while diarrhoea, pneumonia and internal and external parasites caused approximately 52% of the lamb mortality over the same period. The seasonal raw mortality rate of the lambs before weaning was highest in the humid season.     

鼢鼠亚科繁殖特性研究进展

繁殖是生物为延续种群所进行的生理过程,是影响生物种群数量和种群动态的一个重要因素。作为研究地下啮齿动物生活史的一个重要参数,繁殖一直是啮齿动物学研究的焦点之一。鼢鼠亚科动物是地下啮齿动物中重要的一类,栖息于草原、农田和森林,在这些生态系统中占据着重要的位置。但是,由于鼢鼠营地下栖息的生活特性,难以观察,导致繁殖研究难度相对较大,文献报道也相对较少。本文从目前已报道的鼢鼠亚科动物的性比、交配、繁殖强度、胎仔数等,概述了其繁殖研究的一些基本情况,并从研究动物种类、研究方法等进行了小结,以期为今后研究鼢鼠危害控制和草地生物多样性保护研究提供参考依据和技术支撑。     

哺乳动物早期胚胎性别鉴定研究进展

性别控制技术已经成为繁殖生物学中重要的研究课题和研究方向,哺乳动物的性别控制是指通过对精子或胚胎的性别鉴定以达到调控子代性别的目的。目前,哺乳动物性别控制的方法很多,主要有精子控制法和早期胚胎性别控制法等。文章主要介绍了早期胚胎性别鉴定方法的基本原理、研究现状、优缺点及在畜牧业中的应用,为进一步探讨哺乳动物的性别控制提供参考。     

Some Production Characteristics of Sudan Desert Sheep under Range Conditions in North Kordofan,Sudan

The records on the flocks of sheep at El-Obeid Research Station during 1988–1990 were analysed using least-squares mixed-model procedures. The objective was to study some production characteristics of Sudan Desert sheep in North Kordofan, Sudan, in relation to the seasonal variation and husbandry systems. No significant differences (p>0.05) were found between sedentary and nomadic flocks in the number of ewes serviced and the conception, lambing or abortion rates. Mortality rates were significantly (p<0.05) higher in the nomadic flock. The breeding season had a significant effect on all the parameters measured. Higher conception (p<0.05) and lambing (p<0.01) rates were recorded for the rainy and late dry seasons. However, the highest ewe mortality (p<0.01) was in the rainy season. The highest (p<0.01) lamb weights at birth and at 30 days of age were recorded under the nomadic system. None the less, lambs kept under the sedentary system had somewhat higher weight gains from 60 to 150 days of age. Lambs born during the rainy season had the highest birth weights (p<0.05) and the highest weight at 30 days of age. However, the live weights from 60 to 150 days of age were significantly higher in lambs born in the late dry season. The highest lamb mortality was recorded in the lambs born in the rainy season. Lambs born under the nomadic system and during the rainy season had the highest (p<0.05) weights at 30 and 60 days of age, and also higher (p<0.01) mortality rates compared to the other flock×season combinations. It was concluded that the production characteristics of Sudan Desert sheep reflect the seasonal nutritional status and husbandry system. The effects of supplementary feeding on breeding and pregnant ewes, and on the performance of weaned lambs in the area should be studied. Moreover, the socioeconomic factors governing mobility in nomadic flocks should be thoroughly investigated.     

Rusa deer (Cervus timorensis russa) farming in New Caledonia: impact of different feed levels on herd breeding rate and performance of newborn fawns

Objective To measure the impact of undernourishment during the rutting period on the breeding rate of Javan rusa deer and performance of fawns from birth to weaning.
Design A random controlled trial.
Animals Two groups of 37 hinds.
Procedure Group P grazed improved pasture and group M native grassland through the rutting period. Hinds were weighed at the beginning and the end of rutting, at ultrasound scan and prior to fawning. Fawning was monitored.
Results At the end of the rutting period, the mean difference in weight between the two groups was 8.5 kg and the pregnancy rate was 95% for group P and 57% for group M. Fifty births were recorded which equates to a fertility rate at 24 hours of 60% for group P and 30% for group M. Fawn mortality occurring in the first 24 hours affected 26% of all fawns. In 54% of the cases, newborn deaths were subsequent to abandonment by the hind. Average rusa fawn weight at birth was 3.6 + 0.1 kg, regardless of sex or group. Among fawns that weighed less than 3.0 kg, the mortality rate was 55%. The newborn fawn weight was related to the weight of the hind at ultrasound scanning. The weaning rate at 20 weeks was 84% for both groups. Mean weight gains for sucking fawns were 150 g per day for the first 2 months and 108 g per day from 60 to 120 days regardless of sex or group. The mean weight at 60 and 120 days was 12.7 kg and 18.5 kg, respectively. Two regression equations enable the calculation of the weight at 60 and 120 days using the fawn weight at birth and hind weight at the beginning of the rutting period.
Conclusion A 5% weight loss for the hinds resulting from undernourishment during the rutting period causes a 32% reduction in the herd fertility rate, without affecting the weight of newborn fawns, the survival rate nor growth performances in the sucking phase.     

Reproduction and Mortality in a Colony of Captive Greater Cane Rats,Thryonomys swinderianus,Temminck

The reproductive performance and mortalities in a colony of captive greater cane rats, Thryonomys swinderianus, were monitored from 1992 to 1998 at the Grasscutter Domestication Centre, Achimota, Ghana. The animals were kept in cages and exposed to constant lighting from a 100 W electric light bulb during the night. The diet consisted mainly of freshly cut Panicum maximum (guinea grass) fed ad libitum, with occasional supplements of cassava and cane sugar. The results indicate that the mean litter size and litter weight were 2.9±0.51 and 439.4±81.23 g, respectively. These figures are low compared to those reported elsewhere. However, the mean birth weight was 151.2±11.08 g, higher by 12% than previously reported values. It is considered that poor nutrition, excessive exposure to light and stress were responsible for the relatively poor reproductive performance reported in these animals. The main causes of death were traumatic injuries (32%) and pulmonary congestion (16%).     

动物的性别控制

动物的性别控制是指通过对精子或胚胎的性别鉴定以达到调控子代性别的目的,人为调控动物的性别是人类长期以来的愿望,随着胚胎冷冻、胚胎切割、体细胞克隆技术的日渐成熟,动物的性别控制显得更为重要。     

凤头鸭胚性反转建立及性别候选基因的表达

试验通过对鸭胚注射芳香化酶抑制剂(AI)和β-雌二醇(E2)构建性反转模型,观察其性腺外观形态变化,并荧光定量检测雌性基因P450arom、FOXL2、SF-1和雄性基因DMRT1、SOX9、AMH等6个基因在性反转和正常鸭胚中的表达情况。结果显示:芳香化酶抑制剂能促进公鸭性腺发育,母鸭表现雄化;雌二醇能促进母鸭性腺分化,公鸭表现雌化。DMRT1、SOX9、AMH表达趋势相似,AI促进基因表达使胚胎雄化;E2抑制基因表达使胚胎雌化。P450arom、FOXL2、SF-1在AI组中被抑制使胚胎雄化,在E2组中得到促进发生雌化。该研究结果为研究鸭胚性反转机制奠定理论基础。     

不同苜蓿品种自交结实性的研究

对10个苜蓿品种、3种自交方式、2种授粉方式处理的苜蓿自交结实性进行了调查.结果表明,不同处理的苜蓿自交结实率各不相同,均存在着显著性差异,但单荚螺旋敬和种子千粒重各处理间差异不显著.3种自交方式的自交结实率按照单花自交一同花序自交一同植株自交的顺序呈递增趋势.但同花序自交与同植株自交的差异不显著,而均与单花自交的差异达显著水平;人工授粉与天然授粉相比,可以显著提高苜蓿的自交结实率.但人工授粉对单花自交的结实率提高不显著,主要提高同花序自交和同植株自交的结实率.     

哺乳动物性别决定相关基因研究进展

性别控制技术在畜牧生产中具有很强的应用性,其基础主要来源于性别决定。哺乳动物性别决定是一个复杂的过程,其主要以Sry基因为主效基因,同时,还受其他基因级联作用调控。主要性别决定的基因有Sf1基因、Wt1基因、Wnt4基因、Dax1基因等,对哺乳动物性别决定机制及其相关基因研究进展进行综述,以期为哺乳动物性别决定相关基因及分子机理研究提供参考。     

Growth Performance and Reproductive Traits at First Parity of New Zealand White Female Rabbits as Affected by Heat Stress and Its Alleviation under Egyptian Conditions

Exposing growing and adult New Zealand White (NZW) female rabbits to severe heat stress (temperature–humidity index = 28.9) during summer adversely affected their growth and reproductive traits. The traits that declined significantly (p<0.01) were the live body weight, daily weight gain and feed intake of growing rabbits, and the litter size and litter weight at weaning (p<0.05) and the pre-weaning weight gain of pups (p<0.01) for adult females. The conception rate declined considerably with heat stress. The declines in the values of the digestibility coefficients due to heat stress were 7.9% (p<0.05) for dry matter (DM), 8.1% (p<0.05) for crude protein (CP) and 1.0% for crude fibre (CF). The traits that increased significantly (p<0.01) due to heat stress were water intake, water/feed ratio and rectal temperature in growing rabbits and pre-weaning mortality for adult females.Alleviation of heat stress in the growing and adult female NZW rabbits was more efficient with drinking cool water (10–15°C; between 10:00 and 17:00) than with supplementation with palm oil (as a source of energy) or natural clay (as a natural enhancer to growth and milk production). Supplying the animals with cool drinking water gave the highest body weight and weight gain, conception rate, litter size and weight and digestibility coefficients for DM and CP and the lowest rectal temperature, respiration rate and pre-weaning mortality.The loss in rabbit production pertaining to heat stress estimated from the percentages of decline in conception rate×pre-weaning mortality×litter weight at weaning was 73.0%. The provision of cool water restored 11/12 of heat loss.     

两性异型红隼的子代性比研究

Fisher经典的性比分配理论预测:如果双亲繁殖雄性和雌性子代的代价相同,那么子代的性比应趋于平衡.然而,性比组成是长期进化的结果,常因不同因素的影响而出现偏离.文献报道猛禽由于存在不同形式的两性异型现象而导致子代性比常出现偏离,但子代性比偏离方向因种而异.本研究中我们对红隼(Falco tinnunculus)子代的性比组成进行了调查,目的是检验红隼子代性比是否受产卵日期、产卵顺序、卵重、出雏顺序或窝卵数影响.在窝水平上,红隼(雄性)的初级性比为47.0%,没有偏离0.5,但次级性比为40.8%,显著偏离0.5(p=0.029).在种群水平上,初级性比和次级性比都没有出现偏离.窝卵数和卵重影响红隼的次级性比组成,窝卵数越大,雄性后代数量越多,且发育为雄性后代的卵重较发育为雌性后代的重.初级性比和次级性比都受到产卵日期的影响,产卵越早,雄性后代比例越高.     

Patterns of crossfostering and piglet mortality on commercial U.S. and Canadian swine farms

A data base of 300 farms using computerized records was used to examine the extent and timing of crossfostering being practiced in commercial herds in the Midwestern U.S. and Canada in 1994–1995. Crossfostering was used on 98% of farms. Across all farms, the mean percent of piglets crossfostered was 8.6%. Farms varied greatly in the age at which they moved piglets. The 20 farms that moved piglets the earliest after birth were classified as early-move farms and the 20 that moved the oldest piglets were classified as late-move farms. Early-move and late-move farms did not differ in herd size (P = 0.14), average parity of farrowed sows (P = 0.47) or age at weaning (P = 0.37). There were differences between early-move and late-move farms in percent of piglets fostered (P = 0.0001), pigs born alive/litter (P = 0.04), and pre-weaning mortality (P = 0.0005). A subset of late-move farms that were part of an integrated production group had unique production parameters that suggested inaccurate record-keeping.     

一氧化氮对动物生殖机能的影响

一氧化氮(NO)是动物体内发挥多种生物学效应的自由基,是一种重要的生物信使,它几乎对哺乳动物的各个系统都会产生一定的作用。近几年的研究结果也表明,NO对动物生殖机能的许多方面都有很大的影响。文章着重介绍了NO对动物排卵前LH峰、排卵、胚胎附植和发育、妊娠、分娩以及NO对动物精子获能、精子活力、阴茎勃起等生殖过程的影响。     

我国香根草繁殖方法的研究进展

针对香根草Vetiveria zizanioides需求量较大和种苗供不应求的现状,综述了我国香根草繁殖方法的研究进展.认为整合组织培养法和种子繁殖法的独特优势,大力开展以种子为材料的组织培养研究,使香根草组织培养工作系统化和产业化,并诱导提高香根草的结籽率,是解决目前我国香根草繁殖慢、种苗供不应求的难题和进一步推广应用的有效途径.