A syndrome of hepatogenous photosensitisation, resembling geeldikkop, in sheep grazing Tribulus terrestris

Two outbreaks of photosensitivity disease occurred in weaner sheep in south western New South Wales during early autumn 1982. In each instance there was a history of access to the annual herb, Tribulus terrestris and both the clinical and pathological findings were consistent with geeldikkop, a major disease in the Republic of South Africa. The prevalence rates of clinical cases were 21 and 37%, while the case fatality rates approached 70%. Clinical signs were dominated by jaundice and photosensitisation. Ochre and khaki discolouration were present in the liver and kidneys, respectively. Histopathologically, the most characteristic lesion was the presence of acicular, cholesterol-like clefts in the lumens of bile ducts and in the cytoplasm of hepatocytes and Kupffer cells. Similar structures were also evident in the lumens of nephrons in association with segmental hyperplasia of the neighbouring tubular epithelium. The possible pathogenesis of the hepatogenous photosensitisation and its resemblance to geeldikkop are discussed.     

Measurement of phylloerythrin (phytoporphyrin) in plasma or serum and skin from sheep photosensitised after ingestion of Narthecium ossifragum

AIM: To establish a method for measuring phylloerythrin in plasma or serum and skin from lambs photosensitised after ingestion of the plant, Narthecium ossifragum, which induces an hepatogenous photosensitisation similar to the disease known as facial eczema in sheep. METHODS: For two successive summers, lambs were grazed on uncultivated pastures containing N. ossifragum. Clinical photosensitisation was deemed to have occurred when symptoms such as restlessness, scratching, oedema and reddening of the skin were observed. Sixteen lambs that exhibited signs of photosensitisation were included in this study in the first year and five in the following year. A total of 16 clinically healthy lambs served as controls. Fluorescence emission and excitation spectra of phylloerythrin were measured in plasma or serum samples from the 21 photosensitised and 16 non-photosensitised lambs. In the first year of the study, skin samples were collected post mortem from the ear, lip, neck, nose, leg, belly, udder, back, vulva and perineal region, from all photosensitised and from seven non-photosensitised lambs, and examined by fixing them between two glass plates (each of 1 mm thickness) and placing them at a fixed angle in front of a fluorescence spectrofluorometer. RESULTS: All plasma or serum samples obtained from the photosensitised lambs exhibited strong phylloerythrin-like fluorescence of identical spectra; maximum fluorescence was at 650 and 711 nm, and maximum excitation at 425 nm. Emission spectra obtained from plasma or sera from non-photosensitised sheep grazing the same N. ossifragum-containing pastures exhibited either no or only minor fluorescence. Phylloerythrin concentration in plasma or serum exceeded 0.3 microg/ml before clinical photosensitisation occurred, whereas the concentration in samples from clinically healthy lambs was <0.05 microg/ml. Fluorescence from skin samples from the photosensitised lambs showed emission peaks at 650, 670 and 711 nm, whereas the phylloerythrin emission peaks at 650 and 711 nm were not observed in skin from clinically healthy lambs. CONCLUSION: Plasma concentrations of phylloerythrin in healthy sheep were <0.05 microg/ml. Clinical signs of photosensitisation were not observed until the concentration of phylloerythrin in plasma exceeded 0.3 microg/ml. This is the first reported spectroscopic method for analysis of phylloerythrin and the only one which does not involve exposure of the analyst to hazardous chemicals. It has the additional benefit of distinguishing between hepatogenous and primary photosensitisation.     

Suspected photosensitisation in lambs grazing birdsfoot trefoil (Lotus corniculatus)

Suspected photosensitisation occurred in three groups of lambs grazing birdsfoot trefoil (Lotus corniculatus c.v. Grasslands Goldie). In one group, sucking lambs aged about 10 weeks, grazing birdsfoot trefoil, developed skin lesions while lambs of a similar age and from the same flock grazing lucerne (Medicago sativa) or a mixed sward of both species showed no signs of photosensitisation. Affected lambs had lesions on their backs and ears. In a few animals the tips of the ears were shortened by 2-3 cm. In the affected lambs, serum liver enzymes (gamma-glutamyltransferase, glutamate dehydrogenase), bilirubin and serum Vitamin B12 levels were within the normal range. At necropsy, no significant pathological changes were detected in the liver and histological changes in the skin were consistent with primary photosensitisation. In the second group, three of 80 weaned lambs grazing the same birdsfoot trefoil at a restricted intake were affected in the same manner as the first group. In the third group, 15 animals from 28 sets of sucking twin lambs were also affected. In only two sets of twins were both lambs affected. None of the ewes grazing with the lambs in the first or third groups showed any clinical signs of photosensitisation.     

WHITE LIVER DISEASE IN LAMBS

An outbreak of white liver disease in lambs in Western Australia is described. The disease affected 2- to 3-month-old lambs and was characterised by liver damage, severe ill-thrift, depression, serous ocular discharge, photosensitisation, and a high mortality rate. Transient central nervous system signs occurred. A positive response to vitamin B₁₂ therapy was demonstrated.     

Spectrofluorometric analysis of phylloerythrin (phytoporphyrin) in plasma and tissues from sheep suffering from facial eczema

AIMS: To study the increase in phylloerythrin concentration in plasma and the disposition of phylloerythrin in skin and other tissues of sheep in which the hepatogenous photosensitisation,facial eczema, had been experimentally induced by dosing with the mycotoxin, sporidesmin. Spectroscopic differences between plasma and skin measurements of animals kept inside and outside after dosing were also studied in order to establish whether phylloerythrin undergoes photodegradation when exposed to sunlight. METHODS: Twenty-six Romney x Polled Dorset (25-30 kg)weaned female lambs were purchased from a commercial flock in the Waikato region, New Zealand. Twenty-two of these lambs were dosed with 0.25 mg sporidesmin/kg liveweight on each of two consecutive days (Days -1 and 0); the remaining four lambs served as controls. Both sporidesmin-dosed lambs and controls were randomly divided into two penned groups, one group housed inside in a darkened room and the others outside, exposed to natural sunlight. The lambs were fed green lucerne pellets and lucerne chaff ad libitum for 10 days prior to dosing and until Day 12 after the first dose; thereafter, all the lambs were fed fresh, cut grass (mainly ryegrass) ad libitum, until the end of the experimental period on Day 26. Plasma samples collected on Days -2, 7, 10, 12, 14, 17, 20 and 25were analysed for gamma glutamyltransferase (GGT) activity, bilirubin concentration, and the fluorescence spectrum of phylloerythrin. Spectrofluorometric analysis of phylloerythrin in skin was performed in vivo on the same days, using an external fiber-optic probe. RESULTS: Eight of 11 lambs (73%) kept outside after sporidesmin dosing became photosensitised during the experimental period. None of the sporidesmin-dosed animals kept inside showed clinical signs of photosensitisation. The GGT activity in plasma increased exponentially during the experimental period in all sporidesmin-dosed animals until it reached a plateau. All plasma obtained from sporidesmin-dosed sheep had spectral characteristics similar to those of phylloerythrin, namely a peak in the excitation spectrum at 422 nm and strong emission band at 650 (SE 1) and 709 (SE 1) nm. The fluorescence under excitation at 422 nm of phylloerythrin added to plasma from control lambs had identical peaks. Emission spectra obtained from plasma from healthy sheep without addition of phylloerythrin showed either no fluorescence or minor fluorescence at around 671 nm. Fluorescence in skin of sporidesmin-dosed animals had similar spectra to that in plasma. The appearance of the phylloerythrin-like spectra occurred 2-3 days later in the skin than in plasma, and phylloerythrin in sunlight-exposed skin did not suffer photodegradation during the course of the study. CONCLUSION: Plasma concentrations of phylloerythrin in healthy sheep were <0.1 micromol/l, and clinical signs of photosensitisation were not evident until concentrations exceeded 0.3 micromol/l. Plasma concentrations of phylloerythrin rose as high as 4.9 micromol/l in some animals. The concentration of phylloerythrin in skin began increasing 2-3 days later than that in blood. Hepatogenous photosensitisation can be diagnosed by analysis of plasma phylloerythrin concentrations using a spectroscopic method.     

Accumulation of Sapogenin Conjugates and Histological Changes in the Liver and Kidneys of Lambs Suffering from Alveld,a Hepatogenous Photosensitization Disease of Sheep Grazing Narthecium ossifragum

Sixteen lambs exhibiting hepatogenous photosensitization (alveld) after grazing pasture containing Narthecium ossifragum and seven nonphotosensitized lambs grazing the same pastures were studied. All the alveld-affected lambs revealed liver damage dominated by single cell necrosis, portal fibroplasia and bile duct proliferation. Crystalloid clefts were demonstrated in the bile ducts of two and in the hepatocytes and Kupffer cells of nine photosensitized lambs. Plasma bilirubin concentration was severely increased in ten of the cases of alveld whereas the activity of aspartate aminotransferase was moderately to severely increased in seven cases. The activity of glutamate dehydrogenase was moderately elevated in one of the photosensitized lambs. The main histopathological findings in the kidneys from the alveld-affected lambs were dilated tubules, often with eosinophilic material in the tubular lumina. Regenerative changes were seen in a large proportion of the renal sections. Elevated plasma concentrations of urea and creatinine, and the renal histopathological changes, suggested that the photosensitized lambs had been through a phase of renal injury. Analysis of the free and conjugated sapogenin content in liver tissue and bile was performed by gas chromatography–mass spectrometry. There were significantly higher concentrations of conjugated episapogenins in both the liver and bile in the alveld-affected lambs than in the nonphotosensitized lambs.     

PERINATAL LAMB MORTALITY IN WESTERN AUSTRALIA: 5. VIBRIONIC INFECTION

Vibrionic abortion was diagnosed in sheep on 48 occasions between 1963-65 and 3 of these were associated with other major abortion pathogens. The outbreaks were scattered throughout the agricultural area of Western Australia. Time-of-death of 91 infected lambs was: ante-parturient death 50.5%, parturient death 13.2% and post-parturient death 36.3% (deaths occurring immediately after death 28.6%, deaths delayed after death 2.2%, and late post-parturient death 5.5%). The majority of lambs had gross lesions, mainly subcutaneous oedema and excess fluid and fibrin in the serous cavities. The characteristic gross liver foci were present in 37.4% of the infected lambs examined. Seven lambs with signs of starvation had liver lesions: necrotic foci (6) and hepatomegaly (1); Campylobacter fetus subsp. intestinalis was recovered from the liver and/or gall bladder of each of the lambs. Epizootiological observations were reported including outbreaks under hot semi-arid conditions.     

Hepatogenous photosensitisation in Scottish sheep casued by Dicrocoelium dendriticum

Dicrocoeliosis was identified as the probable predisposing cause of weight loss and hepatogenous photosensitisation affecting half of a group of 14month-old ewe lambs on a farm on the Inner Hebridean island of Coll. Oral dosing of the ewe lambs with 15mg/kg albendazole only achieved a 79.2% reduction in Dicrocoelium dendriticum egg count, 21day post treatment. Thus, this report of dicrocoeliosis differs from the disease that occurs elsewhere, both in the severity and nature of its clinical signs, and in the response of the parasite to anthelmintic drug treatment. These differences could indicate the existence of a genetically divergent D. dendriticum population, which may have evolved within the unique and isolated biotope afforded by the machair on the island of Coll. Better understanding of these factors is a prerequisite for effective and sustainable disease control.     

Congenital dilatation of the bile ducts (Caroli's disease) in young dogs

We describe 8 young dogs with congenital dilatation of the intra- and extrahepatic bile ducts and diffuse cystic kidney disease, compatible with Caroli's disease in humans. The dogs were referred between 1980 and 2000 because of chronic disease at an age of 6 months to 3 years. These dogs included 3 Collies, 2 Frisian Stabyhouns, 2 Jack Russell Terriers, and 1 mixed-breed dog. The most common signs were vomiting (6/6), polyuria and polydipsia (4/6), and anorexia (4/6). Ascites was a common finding (4/6). Clinicopathologic abnormalities were available for 6 dogs. All had increased plasma alkaline phosphatase activity and fasting bile acids: increased alanine aminotransferase activity and urea and creatinine concentrations were present in 50% of dogs. Ultrasound examination of the liver showed severely dilated bile ducts without evidence of obstruction, and calcification in all cases but 1. Postmortem examination revealed severe dilatation of the larger intra- and extrahepatic bile ducts. The common bile duct and gall bladder were normal, and the bile system was patent. The ducts contained a clear viscid fluid often with calcified material. Microscopically, marked portal fibrosis was present, often with abnormally structured dilated bile ducts lined with columnar or cuboid epithelium and regularly small calcifications. The lesion was complicated by ascending cholangitis in 1 dog. The kidneys showed marked cortical and medullary fibrosis with a diffuse radial cystic pattern; only slight renal fibrosis was found in the oldest dog. Seven dogs were euthanized without treatment; the oldest dog was alive and well 5 months after diagnosis and was maintained on a protein-restricted diet.     

Pithomycotoxicosis (facial eczema) in ruminants in the Azores, Portugal

Outbreaks of pithomycotoxicosis (facial eczema), a hepatogenous photosensitisation caused by the mycotoxin sporidesmin, have affected ruminants in the Azores Islands of Portugal after warm, humid periods during late summer and autumn. Twenty-two outbreaks were recorded in cattle between 1999 and 2001, affecting 11.4 per cent of the animals in the affected herds, and in 2000 there was an outbreak in one sheep flock in which more than 20 per cent of the sheep died. The clinical signs included decreases in milk production, weight loss, photosensitisation and its sequelae, including death. The animals had high activities of gamma glutamyltransferase in their serum, and icterus and severe liver disease, including biliary hyperplasia and fibrosis, were found postmortem. The characteristic spores of the toxigenic saprophytic fungus Pithomyces chartarum were found on grass; all 381 isolates of the fungus were toxigenic for sporidesmin by elisa, and the results were confirmed by high-performance liquid chromatography analysis. Cattle from farms at greatest risk of pithomycotoxicosis were protected by supplementing their concentrate feed with zinc oxide, or using a slow-release intraruminal zinc bolus.     

Glycogen accumulation and histological changes in the livers of lambs with alveld and experimental sporidesmin intoxication

Alveld is a hepatogenous photosensitization disease seen in lambs grazing Narthecium ossifragum pastures in Norway. Mycotoxins, possibly sporidesmin, have been suspected to cause the liver damage in alveld as in facial eczema. The histological changes in the liver of alveld cases and in lambs photosensitized after experimental sporidesmin intoxication were compared. The liver damage characterized by necrosis in single centrilobular hepatocytes, was of the same type in both conditions. Minor to moderate portal fibroplasia and bile duct proliferation were almost always present. Accumulated glycogen was seen in hepatocytes in the centrilobular areas. This was significantly correlated to the enzymatically measured glycogen content and there was good correlation between parenchymal damage and glycogen accumulation. The glucose-6-phosphatase and glycogen phosphorylase activities were normal. These findings indicate that parenchymal damage, rather than obstruction of the bile ducts, caused the retention of phylloerythrin both in alveld cases and in experimentally sporidesmin-intoxicated lambs. The accumulation of glycogen could not be explained.Abbreviations HE haematoxylin and eoson - PAS periodic acid Schiff - EDTA ethylene diamine tetracetic acid     

Outbreaks of photosensitisation and deaths in cattle due to Myoporum aff.Insulare R. Br. toxicity

Outbreaks of photosensitisation and deaths in cattle on 5 farms in Victoria occurred following access to Myoporum affinity insulare. Signs were observed 2 to 6 days after access to myoporum trees or pruned branches and included depression, anorexia, photosensitisation, constipation, agalactia, jaundice, and mucosal petechiation. Serum gamma glutamyl transferase and aspartate amino transferase levels were elevated in all cases. Gross findings in fatally intoxicated cows consisted of widespread haemorrhages and pale yellow mottling of the liver. Distinctive histological lesions of periportal hepatic necrosis and bile duct proliferation were seen in all cases. An 8-month-old heifer given 30 g/kg fresh minced leaves by stomach tube died approximately 70 h after initial dosing. Post-mortem findings of widespread haemorrhage and hepatic periportal necrosis and bile duct proliferation were identical to those of field cases.     

Encephalomyocarditis virus disease of pigs associated with a plague of rodents

An epizootic of encephalomyocarditis virus (EMCV) disease in pigs in the central west of New South Wales in association with a plague of mice (Mus musculus) in 1984 is described. The disease was confirmed in 47 outbreaks in 37 piggeries and 1152 pigs died, representing an overall death rate of 17.4% in pigs considered at risk. The disease was diagnosed in both intensively housed pigs and pigs farmed outdoors, with mortality rates higher in piggeries with less than 50 sows. The age at which pigs died ranged from 4 days to 24 weeks with higher death rates in younger pigs. Serological testing of pigs slaughtered at Blayney abattoir indicated EMCV infection to be more widespread than the disease reported. Mice were present in all piggeries reporting the disease while rats were present in 66% of the outbreaks. The role of rodents as natural reservoirs of EMCV and the possibility of variations in pathogenicity amongst strains of the virus are discussed.     

Anaemia in housed lambs: effects of oral iron on clinical pathology and performance

An experiment including 39 pairs of housed twin lambs was performed to evaluate the effect of an oral iron supplement (Fe-MAX Starter) on clinical pathology, growth rates and disease occurrence. Significant differences between the iron supplemented group (Fe-group) and the controls were seen, for varying periods of time, for all red blood cell and iron parameters examined. In spite of this, 25% of the iron supplemented lambs had haemoglobin values below 80 g/L 4 weeks after treatment, whereas 33% of the controls had corresponding values 3 weeks after treatment, indicating that one single iron dose was insufficient to prevent iron deficiency anaemia. No significant positive effect on live weights was seen. However, the Fe-group had a poorer daily weight gain during the first week after dosing (p < 0.01), but a better daily gain during the second (p < 0.01) and third weeks. No effects were seen on disease occurrence. An additional trial with iron dextran injections to 5 untreated 21 days old lambs with varying haemoglobin values, revealed a rapid increase in the red cell distribution in anaemic lambs, with production of macrocytic, mainly normochromic erythrocytes. The new erythrocyte population was visible on the cytogram after 2 to 3 days and on the histogram after 5 days.     

Naturally occurring and experimental Stachys arvensis (staggerweed) toxicity in lambs in New Zealand

Stachys arvensis (staggerweed) is a common, widely distributed weed of cultivated and waste land with the potential to intoxicate sheep. Two naturally occurring outbreaks of suspected staggerweed toxicity in the lower North Island were investigated. Affected lambs had been recently moved onto staggerweed-contaminated Brassica spp. crops. In total, 150/1,200 (13%) lambs developed hindlimb paresis, a fine generalised muscular tremor, and hunched posture. When forced to move, many became recumbent. Most lambs recovered within 48 h of removal from staggerweed, although a few developed clinical signs again when transported 2–3 weeks later. Grossly, affected lambs had large amounts of staggerweed plant material and seeds within the rumen. Histopathology showed mild, multifocal degeneration of the white matter tracts of the central nervous system (CNS), most commonly in the ventral funiculi of the spinal cord, and acute, mild to moderate, multifocal degeneration of skeletal muscles. Creatine kinase (CK) activity in serum was mildly to markedly elevated in affected lambs. In a feeding trial, ten 10-month-old Romney lambs were randomly assigned to equal treatment and control groups. Treated lambs were drenched with a liquid extract of staggerweed once daily for 7 days. Three of five treated lambs developed mild exercise intolerance, and 1/5 displayed mild paresis of the hindlimbs, slightly crouched hindlimb stance, and shortened gait, on days 6 and 7. Histologically, 4/5 treated lambs had degeneration in white matter tracts of the CNS, indistinguishable from those seen in the lambs in the outbreak, and in 1/5 lambs there was scattered regeneration of skeletal muscle. CK activity in serum in treated lambs was not significantly higher than that in control lambs. None of the control lambs developed significant clinical signs, histological changes or increases in CK activity in serum. The clinical signs and lesions observed in both the outbreaks and feeding trial were similar to those previously described in studies in Australia, with the exception that myodegeneration was more prominent in the outbreaks in New Zealand. Further characterisation of the pathogenesis of staggerweed toxicity and its potential role as a food safety hazard will be facilitated through identification of the toxic principle(s).     

Pathological,serological, and virological findings in sheep infected simultaneously with <Emphasis Type="Italic">Bluetongue</Emphasis>, <Emphasis Type="Italic">Peste-des-petits-ruminants</Emphasis>, and <Emphasis Type="Italic">Sheeppox viruses</Emphasis>

In this study, pathological, serological and virological examinations were performed on 15 sheep from a flock of 250 sheep and lambs that suffer from simultaneous naturally occurring BTV, PPRV and SPV outbreaks. SPV was diagnosed macroscopically and histopathologically, BTV was diagnosed by ELISA, and PPRV was diagnosed pathologically and by ELISA. Clinically fever, diarrhea, depression, polypnea, conjunctivitis, lacrimation, rhinitis, erosive stomatitis, edema of eyelids, photophobia, cutaneous eruption with erythematous areas especially noticeable in wool-free parts of the body and axilla lesions evolving into papules were observed. At necropsy, the most effected organs were lungs and gut. Subepicardial hemorrhages were also commonly seen. While typical pox lesions were observed in some lambs, usually fibrinous pleuropneumonia was more prominent lung lesion. SPV and PPRV lesions were seen at the histopathological examination of the lesioned tissues, BT lesions were mild than SPV and PPRV microscopically. Serum and leukocyte samples of 15 animals were examined for PPRV and BTV by ELISA; 5 samples were positive for PPRV and 6 BTV, 4 were positive for both PPRV and BTV simultaneously. One hundred animals died, most were lambs. Mortality rates were 100% in lambs and 80% in the herd.     

B-mode and color Doppler sonography of kidneys in healthy lambs and lambs with urolithiasis

The objectives of this study were to determine some morphological characteristics of kidneys and resistive index (RI) changes in renal interlobar artery using B-Mode and color coded doppler sonography in lambs with urolithiasis. The study was performed in 14 male lambs (8 patients, 6 healthy) aged between 2-2.5 months in the same herd. The kidneys had a mean length of 55.6 +/- 1.6 mm, a width of 31.8 +/- 1.2 mm and a parenchymal width of 10.6 +/- 0.6 mm in healthy lambs. These values were 95.4 +/- 3.6., 52.4 +/- 1.3 and 8.75 +/- 0.5 mm, respectively in lambs with urolithiasis. These differences between both groups were significant. Furthermore, the mean resistive index values in lambs with urolithiasis (0.81 +/- 0.017 m/sn) were significantly higher than controls (0.62 +/- 0.013 m/sn). It was concluded that B-Mode and color coded doppler sonography might provide useful information for detection of changes in kidneys of lambs with urolithiasis like hydronephrosis and renal swelling as well as elevated resistance in the renal interlobar artery.     

Lamb and Kid Mortality in Village Flocks in the Coastal Savanna Zone of Ghana

A cohort study was designed to observe and follow up mortality in lambs and kids in 88 flocks of sheep and goats under the traditional production system in five villages within the coastal savanna zone of Ghana over a 2-year period. The overall mortality rates for kids and lambs were 30.8% and 33.5%, respectively. Significantly higher proportions of kids (80.2%) and lambs (75.6%) up to 3 months of age died compared to kids and lambs from 4 to 12 months of age. The differences in mortality rates, either between male and female kids and lambs or between single-born and multiple-birth kids and lambs, were not significant. The odds ratio (OR) and relative risks (RR) for lambs and kids, on the basis of sex and birth types, were not significant; neither were the values obtained for attributable risk, attributable fraction, population attributable risk and population attributable fraction. The overall mortality rate on the basis of species of animal was not significant. At the village level, significant differences in the proportions of mortality on the basis of sex were seen in two villages. At Akotokyir, more male lambs (54.2%) died compared to females (27.6%), while at Apewosika more female lambs (42.2%) died compared to males (16.7%). The only significant difference in mortality proportions on the basis of birth type at the village level was seen at Apewosika, where more single-born kids died (52.8%) compared to kids born with sibling(s) (28.4%). The significant ORs for mortalities were 3.10 for male lambs at Akotokyir, 3.35 for female lambs at Apewosika and 2.82 for single-born kids at Apewosika. The corresponding RRs were equally significant. On the basis of species, significantly more lambs died at Akotokyir (44.2%) and Kwesimprah (44.7%) compared to kids. The implications of these findings are discussed.     

不同品种绵羔羊超数排卵及胚胎体外生产技术研究

探讨品种对羔羊超数排卵效果和卵母细胞发育能力的影响,并将体外受精胚胎进行了移植,为研究利用绵羊羔羊卵母细胞生产后代提供理论和技术方法。对4～8周龄不同品种羔羊用FSH+PSMG处理后获得的平均卵母细胞数量和体外胚胎卵裂率和囊胚率进行了比较,并比较成熟液中有无β-巯基乙醇对胚胎卵裂率和囊胚率的影响。结果:各品种获得的平均卵母细胞数分别为:哈萨克为210.22枚,湖羊为0枚,美利奴为135.80枚,湖羊与哈萨克的杂交后代为37.80枚,湖羊羔羊和湖羊与哈萨克羊的杂交羔羊获得的平均卵母细胞数显著低于哈萨克羔羊(P<0.01,P<0.05)。哈萨克羔羊卵裂率(69.0%)显著高于湖羊与哈萨克羊杂交羔羊(66.4%,P<0.05);哈萨克羔羊囊胚率(17.5%)和美利奴羔羊囊胚率(16.2%)显著高于湖羊×哈萨克羔羊(13.8%)(P<0.01,P<0.05)。β-巯基乙醇对羔羊胚胎卵裂率影响不显著,对囊胚率影响极显著(P<0.01)。哈萨克羔羊卵子体外受精获得的2-8细胞胚胎进行输卵管移植,14只受体羊中7只妊娠,妊娠率为50.0%;共产羔9只,其中8只存活。