An epidemiological study of parasitic gastroenteritis in sheep under an intensive grazing system

Romanov X Rasa Aragonesa ewes rearing twins and kept on pasture at a mean stocking density of 35 ewes ha-1 were used to study the epidemiology of parasitic gastro-enteritis under an intensive grazing system on irrigated land in the northeast of Spain. Measurements were made of the population of infective larvae on the pasture, level of serum pepsinogen, faecal worm eggs in ewes and lambs, and lamb growth rates. In addition, postmortem worm counts from "indicator" lambs were used to establish the level of infection at each rotational grazing cycle. Two generations of parasites were identified in the experiment. One of them, derived from the eggs deposited the previous autumn, gave rise to the first infection of the animals in March and April. This was responsible for the first outbreak of parasitism in the lambs. This was indicated by an increase in serum pepsinogen levels, the appearance of diarrhoea and a significant decrease in lamb growth rates. Ostertagia spp., Nematodirus spp. and Trichostrongylus spp. were present. The second generation, which appeared during May, was derived from the eggs of the previous generation and gave rise to an outbreak of parasitism in the lambs at the beginning of May and the middle of June. Haemonchus spp. and Chabertia ovina were present. Under the conditions of this experiment, the overwintering larvae have an important epidemiological significance as the gastro-intestinal nematodes are one of the main limiting factors for developing intensive sheep production systems.     

产羔期、补饲水平对考力代羊生产和繁殖性能影响的研究

为了研究草地一绵羊系统中草畜供求间的动态平衡，寻求在人工草地放牧条件下适宜的产羔时期及在此时期给产羔母羊的合理补饲水平，１９９０～１９９３年，在贵州省威宁县灼甫联户示范牧场进行了两期产羔期及补饲水平对绵羊生产性能影响的试验。产羔期的改变，导致了母羊及羔羊体重的不同变化趋势。结果显示出母羊体重对其生产、繁殖性能的重要性。春羔母羊配种前体重较之冬羔母羊提高９．７５ｋｇ，两者产羔率分别为１３９．２％和１１６．１％。春羔母羊较高的双羔率导致了春羔母羊较之冬羔母羊更低的繁殖成活率（分别为９１．２％和１０４．７％）。断奶时，春羔较之冬羔体重高５．２５ｋｇ，但断奶以后这种优势即消失了。补饲水平的差异对母羊及羔羊体重有一定的影响，但在牧草丰富的条件下表现得并不很强烈。     

An outbreak of severe iodine-deficiency goitre in a sheep flock in north-east Victoria

Background Several outbreaks of goitre, considered to be related to iodine deficiency, occurred in sheep flocks throughout Victoria in 2010. Objective We describe one outbreak in Merino–Border Leicester‐cross ewes and their lambs in north‐east Victoria that appeared to be associated with increased rainfall and pasture growth, particularly during the preceding summer and autumn. Results The outbreak was characterised by a four‐fold increase in neonatal lamb deaths and goitre, alopecia and poor skeletal development in the lambs. Most cases occurred in lambs born to 2‐year‐old crossbred ewes that had grazed long, lush perennial pastures throughout their entire pregnancy, whereas few cases occurred in mature crossbred or Merino ewes that had grazed shorter, annual pastures on hill country for 3 weeks in late pregnancy but were otherwise managed similarly. Conclusion Existing recommendations for south‐eastern Australia are that only spring‐lambing ewes in iodine‐deficient areas require iodine supplementation to prevent goitre in years with high autumn–winter rainfall. Aspects of this outbreak suggest that ewes lambing at other times of the year and grazing abundant pasture for prolonged periods may also require supplementation to prevent goitre, even if autumn–winter rainfall does not exceed previously established thresholds.     

Grazing management strategies for the control of parasitic diseases in intensive sheep production systems

The effect of forward (F) and lateral (L) creep grazing, as two possible management alternatives of intensive production systems, on the gastro-intestinal nematode epidemiology of ewes and lambs was studied. Two groups of Romanov x Rasa Aragonesa ewes rearing twins and maintained on an autumn-contaminated pasture at a mean stocking density of 35 ewes ha-1, were used. Measurements were made of the population of infective larvae on the pasture, level of serum pepsinogen, worm eggs in faeces of ewes and lambs, and lambs' growth rate. In addition, post-mortem worm counts from 'indicator' lambs were used to establish the level of infection at each rotational grazing cycle. Two different waves of nematode infection were identified. In both treatments, the over-wintering larvae were responsible for the first outbreak of parasitism which was particularly important for lambs on Treatment F. The second wave of infection apparently came up with several overlapped L3 generations and had different effects on the animals of each group. While early pasture contamination was suffered by the lambs of Treatment F, lambs on Treatment L were not seriously affected until the end of the third grazing cycle (end of May). The different grazing behaviour of lambs in both treatments appeared to be related to the outbreak of parasitism in lambs. The general pattern of liveweight gains was similar for both groups of animals. However, during the first 90 days on pasture lamb growth rate under Treatment L (193 g day-1) was significantly higher than that under Treatment F (164 g day-1). The serum pepsinogen values, worm burdens and liveweight gains indicate that under intensive systems where lateral creep grazing is allowed for lambs, the level of parasite infection is maintained within acceptable limits for the first 90 days on pasture with lambs' growth rate close to their potential. However, the parasitic consequences of grazing under a forward creeping system indicate that anthelmintic drenchings should be used at lambing and at 3-week intervals thereafter during the first 42 days on pasture, after which the risk of contamination from the over-wintering population is over.     

Fostering lambs by odor transfer: the add-on experiment

Lamb-specific odor is used by ewes to discriminate between their own and alien offspring. Recent studies have demonstrated that fostering can be facilitated by transferring own-lamb odor to alien lambs via cloth stockinettes. The objective of the present study was to investigate the effectiveness of the odor-transfer technique in enticing ewes with a single lamb to adopt an additional lamb ("add-on" procedure). Shortly after birth, nylon stockinettes were placed on the single offspring of 49 ewes and 49 additional alien lambs designated for fostering. Approximately 20 h following parturition, stockinettes were removed from 41 natural lambs and placed on alien lambs (experimental treatment). In the control treatment (eight ewes) own and alien lambs retained their own stockinettes. Four acceptance tests were conducted, 24 h apart, starting at the onset of fostering. Successful adoptions were attained for 21 of 31 experimental ewes (68%) exposed to add-on lambs similar in facial coloration to their own lambs. Only 2 of 10 experimental ewes (20%) with whiteface natural lambs adopted blackface add-on lambs. One of eight control ewes (12.5%) adopted an add-on lamb. Of the 24 ewes that adopted alien lambs 10 (41.7%) demonstrated immediate acceptance and 20 (83.3%) had adopted lambs by the second test day. A higher proportion of primiparous than multiparous ewes adopted alien lambs. The presence of own-lamb odor on stockinettes worn by add-on lambs appears to facilitate fostering. However, the presence of own-lamb odor may not be a significant-enough cue to override obvious differences in facial coloration between own and add-on lambs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of worm control strategies in grazing sheep in Denmark.

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.     

Evaluation of dicyclanil (CLiKZiN®) treatment for the early-season protection of ewes against blowfly strike

Protecting sheep against early season myiasis (strike) is a significant problem in northern temperate farming systems, where fully-fleeced ewes and early-season lambs approaching market weight, are at high initial risk. Here, the prevention of early-season blowfly strike in ewes was examined on matched commercial sheep farms in south west England, using a new formulation of dicyclanil (CLiKZiN(?) pour on) with a short withdrawal period of 7 days. The ewes on seven farms received a prophylactic treatment with dicyclanil (CLiKZiN 1.25% pour-on suspension) in April 2011; ewes on three control farms received no treatment. The lambs at all farms remained untreated. No adverse reactions to treatment were recorded. On the treatment farms no ewe strikes were recorded between April and June (10 weeks). On control farms, there were 16 strike cases in ewes over the same period, giving a cumulative incidence of 31 cases per 1000 ewes. On the treatment farms only one lamb was struck whereas at the control farms 10 lamb strikes were recorded. The data demonstrate that CLiKZiN was highly effective at protecting ewes against early season strike-challenge.     

Managing anthelmintic resistance: untreated adult ewes as a source of unselected parasites, and their role in reducing parasite populations

AIMS: To test the hypotheses that when untreated adult ewes are rotationally grazed (follow behind) on pastures after lambs receiving routine anthelmintic treatments, the ewes can function as a source of unselected parasites in refugia, capable of slowing the development of anthelmintic resistance, and suppress the build-up of parasites resulting from the development of anthelmintic resistance. METHODS: Firstly, the potential of untreated adult ewes to slow the development of anthelmintic resistance, and to suppress parasite populations under differing levels of anthelmintic efficacy, was investigated using a simulation model. Secondly, a field trial with three replicates of each treatment compared two grazing systems (lambs only vs lambs followed by ewes) and two types of anthelmintic, viz albendazole (ALB), to which resistance was present (faecal nematode egg count reduction (FECR)=57-59%) and ivermectin plus levamisole (IL), to which resistance was absent (FECR=97-99%), in a factorial treatment structure. Parasite populations were monitored using faecal nematode egg counts (FEC), faecal larval cultures, pasture larval sampling, and slaughter of tracer lambs. Animal performance was measured using liveweight, dag score, body condition score, and fleece weights. RESULTS: Model simulations indicated that parasites cycling in the untreated ewes could slow the development of resistance being selected for by the anthelmintic treatments given to lambs and this could occur without a nett increase in larval numbers on pasture. Further, as worm control in the lambs declined with increasing levels of anthelmintic resistance the ewes increasingly functioned as nett removers of parasite larvae, effectively reducing parasite population size. In the field trial, untreated adult ewes contributed to pasture infestations of most parasite species, but not Nematodirus spp. Parasite species on pasture and infecting lambs changed when ewes were present, but larval populations on pasture in the autumn were no greater than when lambs grazed alone. In the presence of anthelmintic resistance, parasite populations were reduced when ewes grazed in rotation with lambs, implicating the ewes as nett removers of parasite challenge. CONCLUSIONS: Untreated adult ewes were a source of unselected genotypes, capable of slowing the development of anthelmintic resistance in most, but not all, parasite species. Further, the potential of adult ewes to remove from pasture more parasite larvae than they contribute through faecal contamination indicates a potentially useful role in suppressing parasite populations, particularly when worm control in lambs is less effective as a result of anthelmintic resistance.     

High mineral and vitamin E intake by pregnant ewes lowers colostral immunoglobulin G absorption by the lamb

A 2 x 2 factorial arrangement of treatments with 78 mature ewes was used to evaluate the effects of supplementing the pregnant ewe's diet with high levels of minerals and vitamin E on immunoglobulin G (IgG) absorption by the lamb and whether any altered efficacy of IgG absorption was due to the colostrum or to the lamb. The ewes were estrus-synchronized in October and housed in wk 10 of gestation. In the final 7 wk of gestation, a grass silage-based diet, offered ad libitum, was supplemented with 500 g of a 19% CP concentrate, and from 1 wk later until lambing, half the ewes was offered 48 g of a mineral/vitamin supplement containing 6.5 g of Ca, 4.9 g of P, 5.9 g of Mg, 4.0 g of Na, 790 mg of Zn, 3.5 mg of Se, 40 mg of I, 200 mg of Mn, 20 mg of Co, and 40 IU of vitamin E. At birth, the lambs were allocated to one of four treatments in a 2 x 2 factorial arrangement, with lamb origin and colostrum origin as the two factors. The lambs born to ewes not offered the mineral supplement were fed colostrum obtained from their own dams or from ewes in the mineral-supplemented treatment, whereas lambs born to ewes given supplemental minerals were fed colostrum obtained either from their dams or from ewes in the control treatment. The ewes were milked at 1, 10, and 18 h postpartum and the lambs were fed using a stomach tube. A 5-mL blood sample was taken from each lamb at 24 h postpartum for IgG analysis. The level of fecal adhesion to the upper tail/rump area of the lamb was subjectively scored at 72 h postpartum. There was no difference in gestation length, lamb birth weight, colostrum yield, or IgG production (P = 0.16 to 0.82). When ewes were fed supplemental minerals, the serum IgG content of the progeny was lower than in their control counterparts (6.8 vs. 16.1 g/L; P < 0.001), regardless of whether the lamb received colostrum from ewes with or without access to supplementary minerals. The difference in serum IgG concentrations at 24 h postpartum was a direct reflection of a compromised efficiency in IgG absorption. The progeny of ewes with access to minerals had higher (P < 0.05) levels of fecal adhesion, which was not related to the origin of the colostrum, indicating altered digestive function in these lambs. We conclude, using the sheep as a model, that high mineral intakes in late pregnancy not only lower serum IgG concentrations in the lamb, but also that high mineral intakes result in the neonate being preprogrammed at birth so that it is born with a compromised ability to absorb colostral IgG.     

Individual animal risk factors for clinical mastitis in meat sheep in Norway

An m:n matched case–control study was conducted to identify risk factors for ovine clinical mastitis (CM). Data were from a national sheep registry and only ewes that lambed in the spring of 2004 were included. Eligible cases (n = 2857) and controls (n = 76,716) from 1056 flocks of meat sheep were matched on flock and conditional logistic regression was used for analysis of the data. CM risk was associated with age of the ewe and whether or not assistance at lambing was needed owing to dystocia; however, the effects of both these factors were modified by the number of lambs born. In ewes with 1 lamb, increasing age was associated with increased odds of CM (OR = 1.2 for each 1-year increase), while only a slight numerical increase in the odds was observed in ewes with >1 lamb. Dystocia was associated with increased odds of CM in ewes with 1 lamb (OR = 1.7) or 2 lambs (OR = 1.4), while no association was observed in ewes with >2 lambs. The odds of CM increased markedly with increasing number of lambs born to the ewe. For example, odds for 2-year-old ewes without dystocia were 6.7 times greater for those with >3 lambs than for those with 1 lamb. Compared with ewes of old Norwegian breeds, ewes of other breeds were more likely to experience CM (OR = 1.7). Ewes treated for CM at least once during the preceding 3 years had 4.0 times greater odds of CM compared with ewes without a CM history. It is likely that the effect estimates from this study, which are adjusted for breed and unaffected by inter-flock variations, are valid also for other meat sheep populations.     

Use of a long acting injectable formulation of moxidectin to control the periparturient rise in faecal Teladorsagia circumcincta egg output of ewes

A field study was conducted in a sheep flock in the south east of Scotland with a history of ivermectin resistance in Teladorsagia circumcincta. The objective of the study was to compare the effects of single anthelmintic treatments in ewes before turn-out onto pasture that was contaminated with a moderate level of overwintered, ivermectin resistant, T. circumcincta infective larvae. The ewes were treated according to label directions with either a long acting injectable formulation of moxidectin (1mg/kg; affording up to 14weeks persistent action against macrocyclic lactone (ML)-susceptible T. circumcincta) or an oral formulation of moxidectin (0.2mg/kg; affording up to 5weeks persistent action against ML-susceptible T. circumcincta). The lambs were enrolled in the normal management of the farm, and received a total of three oral ivermectin treatments during the 16week study. The efficacy of both treatment strategies in controlling the periparturient rise in faecal nematode worm egg counts and subsequent pasture contamination was assessed from the faecal worm egg counts of the ewes and their lambs between lambing and weaning. Ewes that were treated with the oral formulation of moxidectin shed approximately 3.5 times more T. circumcincta eggs between lambing and weaning than ewes that were treated with the long acting formulation of moxidectin. This difference was reflected in the faecal worm egg counts of the lambs that were grazed alongside the different treatment groups of ewes. The results of the current study demonstrate persistent efficacy of the long acting formulation of moxidectin against an ivermectin resistant T. circumcincta population. The decreased pasture contamination after treatment could lead to improved lamb growth and a need for fewer anthelmintic treatments, thus potentially reducing one possible selection pressure for anthelmintic resistance. However, treatment with the long acting formulation of moxidectin would give rise to fewer susceptible nematodes being present in refugia, which could increase another possible selection pressure for anthelmintic resistance, depending on the subsequent grazing management of that pasture. The rationale for use of a persistent anthelmintic drug to control the periparturient rise in faecal ML-resistant T. circumcincta egg output of the ewes is discussed and potential differences in selection for macrocyclic lactone anthelmintic resistance using the different formulations of moxidectin are acknowledged.     

Efficiency of Duddingtonia flagrans against Trichostrongyle infections of sheep on mountain pastures

The control of sheep nematode parasites in extensive mountain/transhumant management systems using the nematophagous fungus Duddingtonia flagrans was assessed in this study. Two groups of Churra Tensina ewes were allowed to graze for 8 weeks in autumn on two separate paddocks of infected pasture near their winter sheds in the valley. At lambing, ewes and their twin lambs were turned out into the same paddocks for the following 12 weeks. One group of ewes received a daily dose of 5 x 10(5) chlamydospores of Duddingtonia flagrans/kg live weight per day both in autumn and in spring, while the other group was used as a non-treated control. Daily dosing of grazing ewes with the fungus D. flagrans had a clear effect on reducing autumn pasture contamination. This had a subsequent effect on the over-wintering larvae population that was confirmed by a 20% lower worm burden of tracer lambs kept in early spring on the paddock previously grazed by fungus treated ewes. In spring, pasture contamination was also significantly reduced in the paddock grazed by fungi-treated ewes and their lambs showed a 61% lower worm burden and a better performance than the control lambs. Results herein show that fungal spores fed to sheep at critical times with regard to the epidemiology of parasite infection, can have a significant effect on the infective larvae present on pasture, which could further improve lambs performance. This novel approach to parasite control would be of interest amongst both organic and conventional sheep farmers operating in mountain regions.     

Successful fostering of orphan lambs by nonpregnant ewes induced to lactate using exogenous hormone treatment

Six nonpregnant ewes were induced to lactate by an exogenous hormone treatment lasting 6 weeks. At the end of the treatment one alien lamb was adopted by each ewe. Each ewe was initially indifferent to the alien lamb and required only mild restraint to allow the lambs to suck successfully. Maternal interest subsequently increased and strong ewe-lamb bonding was evident by 80 minutes (n=l), 10 hours (n=4) or 24 hours (n=l) in different cases. The lambs required supplementary milk for 4–6 days while milk production by the ewes increased to adequate levels. Thereafter they were reared entirely by the ewes. Another four nonpregnant ewes were induced to lactate by a similar hormone treatment and were then hand-milked thrice daily for 2-3 weeks. One alien lamb was then introduced to each ewe. All four ewes were aggressive towards the lambs which were removed after 10–30 minutes. The ewes were then injected subcu- taneously with 5 mg of oestradiol-17β and were placed in fostering stocks. After a further 3–5 hours the lambs were re-introduced. Strong ewe-lamb bonding occurred during the subsequent 10 hours in all cases. All 10 lambs were reared successfully by these ewes until at least 3 months of age, when observations stopped. It was concluded firstly that nonpregnant ewes induced to lactate artificially will adopt and rear orphan lambs successfully, provided that additional milk is given to meet shortfalls during the first 4–6 days; and secondly that a 5 mg injection of oestradiol-17β may facilitate fostering of lambs by ewes in established lactation whether the lactation is induced artificially or not.     

Successful fostering of orphan lambs by non-pregnant ewes induced to lactate using exogenous hormone treatment

Six nonpregnant ewes were induced to lactate by an exogenous hormone treatment lasting 6 weeks. At the end of the treatment one alien lamb was adopted by each ewe. Each ewe was initially indifferent to the alien lamb and required only mild restraint to allow the lambs to suck successfully. Maternal interest subsequently increased and strong ewe-lamb bonding was evident by 80 minutes (n=1), 10 hours (n=4) or 24 hours (n=1) in different cases. The lambs required supplementary milk for 4-6 days while milk production by the ewes increased to adequate levels. Thereafter they were reared entirely by the ewes. Another four nonpregnant ewes were induced to lactate by a similar hormone treatment and were then hand-milked thrice daily for 23 weeks. One alien lamb was then removed after 10-30 minutes. The ewes were then injected subcutaneously with 5 mg of oestradiol-17beta and were placed in fostering stocks. After a further 3-5 hours the lambs were re-introduced. Strong ewe-lamb bonding occurred during the subsequent 10 hours in all cases. All 10 lambs were reared successfully by these ewes until at least 3 months of age, when observations stopped. It was concluded firstly that nonpregnant ewes induced to lactate artificially will adopt and rear orphan lambs successfully, provided that additional milk is given to meet shortfalls during the first 4-6 days; and secondly that a 5 mg injection of oestradiol-17beta may facilitate fostering of lambs by ewes in established lactation whether the lactation is induced artificially or not.     

THE EFFECT OF ANTHELMINTIC TREATMENT OF MAIDEN EWES IN THE PERIPARTURIENT PERIOD ON PASTURE CONTAMINATION AND PRODUCTION OF PRIME LAMBS

SUMMARY A replicated experiment using first cross Border Leicester/Merino maiden ewes set stocked at the rate of 9.9 per hectare was conducted to examine the effects of treatment of the ewes in the periparturient period (PPP) and treatment of lambs at about 12 weeks of age on the production of prime lambs. All treatments given were thiabendazole. Four groups each of 100 ewes (4 replicates × 25) were treated either pre-lambing, 2 weeks before lambing commenced and again post-lambing, 8 weeks later when lambing was almost complete (DD), pre-lambing only (DO), post-lambing only (OD) or not treated during the lambing period (OO). Lambing commenced 24 July 1972 with the bulk of lambing (98%) occuring within the first 4 weeks of a 6 weeks lambing period. The effectiveness of the drenching regimes was judged by observing bodyweight gains per day during four overlapping intervals between birth and 18 weeks of age. The bodyweight gain of lambs up to 18 weeks and the number of lambs exceeding a target weight of 33 kg at 18 weeks of age were considered to be critical measurements of production efficiency. Significant bodyweight differences were observed within 30 days from birth, favouring DD and DO over OD and OO lambs (p < 0.01). These differences continued until 12 weeks of age at a reduced level of significance (p < 0.05). By 18 weeks of age the results favoured DD over DO (p <0.05) over both OD and OO lambs (p < 0.05). Further differences were created by the treatment of lambs at 12 weeks of age (p < 0.01). At no time during the entire experiment were any significant differences observed between OD and OO lambs. The periparturient rise (PPR) in faecal nematode egg output was monitored throughout the experiment. Anthelmintic treatment of the ewes in the PPP did not eliminate the PPR but did affect the onset, magnitude and duration of the PPR which was either delayed by the prelambing treatment or truncated by the post-lambing treatment; treatments both before and after lambing delayed and depressed the PPR and reduced total pasture contamination by 29%. An effect on bodyweight of ewes was also observed with ewes being treated pre-lambing (Groups DD, DO) being significantly heavier at 18 weeks post-lambing than OD and OO ewes (p < 0.05). The observed effects on lamb production have been attributed in the main to an apparent, though not specifically measured, effect on lactation in those ewes being treated pre-lambing. The effect of delayed (Groups DD, DO) and/or reduced (Group DD) pasture contamination was considered to be additive to the earlier lactation response. Treatment of lambs at 12 weeks did not obscure these responses.     

Evaluation of ewe and lamb immune response when ewes were supplemented with vitamin E

Fifty-two Targhee twin-bearing ewes were used in a factorial arrangement of treatments to investigate the role of supplemental vitamin E (vit E); 0 (NE) vs 400 IU of vit E x ewe x (-1)d(-1) (E) and parainfluenza type 3 (PI3) vaccination; none (NP) vs PI3 vaccination (P) in immune function. Parainfluenza type 3 vaccination was used to evoke an immune response. Ewes receiving PI3 were vaccinated at 49 and 21 d before the expected lambing date. Ewes receiving vit E were orally dosed daily, 32 to 0 d before lambing. Blood was collected from ewes at the time of the initial PI3 vaccination and 4 h postpartum. Blood was collected from lambs (n = 104) at 3 d postpartum. Ewe and lamb sera were analyzed for anti-PI3 antibody titers, immunoglobulin G (IgG) titers, and vit E concentrations. Colostrum was collected 4 h postpartum and analyzed for IgG. The model for ewe and lamb analysis included the main effects of vit E and PI3, sex (lambs model only), and their interactions. No interactions were detected (P > 0.20) for any ewe or lamb variables. Serum anti-PI3 titers were greater (P < 0.01) in P ewes and their lambs than NP ewes and their lambs. Serum vit E concentrations were greater (P < 0.01) in E ewes and their lambs than NE ewes and their lambs. Colostral IgG titers and serum anti-PI3 titers did not differ (P > 0.20) between E and NE ewes. Serum IgG titers in E ewes and their lambs did not differ (P > 0.15) from IgG titers in NE ewes and their lambs. Lamb anti-PI3 titers did not differ (P = 0.76) between lambs reared by E and NE ewes. These results indicate that, although supplemental vit E to the ewe increased lamb serum vit E concentration, it had no effect on measures used in this study to assess humoral immunity in the ewe or passive immunity to the lamb.     

The impact of daily Duddingtonia flagrans application to lactating ewes on gastrointestinal nematodes infections in their lambs in the Netherlands

Two experiments were performed in 2002 and 2003 to evaluate the effect of biological control of gastrointestinal nematodes in sheep through the daily feeding of 500,000 chlamydospores of Duddingtonia flagrans/kg bodyweight to lactating ewes during the first 9 weeks with their young lambs on pasture. In both experiments four groups of eight ewes and their April-borne lambs were used. They were turned out on four separate plots (plots A) at the beginning of May, moved to similar separate plots after 3 (plots B) and 6 weeks (plots C), respectively, and weaning occurred after 9 weeks. In both experiments, two groups were fed spores daily while the two other groups served as controls. The effect of D. flagrans application was evaluated through faecal egg counts of ewes and lambs, the yield of faecal cultures in ewes, pasture larval counts and worm counts of lambs and tracer lambs. The results demonstrated no effect of D. flagrans application during the first 5 (2002) or 4 (2003) weeks. Subsequently, fungus application strongly reduced the yield in faecal cultures of the ewes. This was, however, not reflected in the pasture larval counts, but lower worm burdens were observed in tracer lambs of 'treated' plots C in 2002 than on those of 'control' plots. In 2003 worm burdens in 'treated' lambs returned to plots B were lower than those of 'control' lambs and a tendency for the same was observed for plots C. However, in all groups, lambs and tracer lambs developed severe haemonchosis.     

Inheritance of fecal egg count and packed cell volume and their relationship with production traits in sheep infected with Haemonchus contortus

This study describes responses to artificial infection with Haemonchus contortus in ewes and lambs of 50% Dorset, 25% Rambouillet, and 25% Finn-sheep ancestry and provides estimates of genetic parameters for measures of parasite resistance. One hundred ninety-eight ewes out of 64 sires, and 386 lambs out of 25 sires were evaluated in autumn and spring of 2 yr. Ewes were dewormed shortly after weaning their lambs and lambs were dewormed at about 120 d of age. One week after deworming, ewes and lambs were dosed with approximately 10,000 infective larvae of H. contortus. After infection, BW, fecal egg counts (FEC), and packed cell volume (PCV) were measured weekly for 7 wk in lambs kept in drylot and fortnightly for 11 wk in ewes on pasture. Summary traits were defined as initial PCV, mean BW across all times, and means for PCV (MPCV) and log-transformed FEC (MLFEC) at wk 3 to 7 after infection for lambs and wk 3 to 11 after infection for ewes. Ewes and lambs did not lose weight overall in any year or season, but there was no consistent effect of year or lambing season on mean LFEC or mean PCV during infection in either ewes or lambs. Yearling ewes were less resistant to infection than older ewes, with lower PCV (P < 0.05) and higher LFEC (P < 0.05). During infection, PCV was positively correlated with BW and negatively correlated with LFEC in both ewes and lambs. In lambs, heritabilities were 0.39 (P < 0.01) for PCV, 0.10 (P < 0.05) for LFEC across all measurement times, and 0.19 (P < 0.01) for three measures of LFEC taken at the peak of infection. Heritability estimates for ewes were 0.15 (P < 0.05) for PCV and 0.31 (P < 0.01) for LFEC. Repeatabilities for LFEC and PCV across measurement times were moderate in ewes and lambs. Correlations between dam and lamb records for MLFEC were generally low, suggesting different mechanisms of resistance in lambs and nonlactating ewes. Ewes with higher genetic merit for growth as lambs were less resistant to infection as adults, but genetic merit for fertility and prolificacy were not related to parasite resistance. Lambs with higher genetic merit for body weight were more resistant to infection. Selection for resistance to H. contortus is therefore possible and should not adversely affect growth of lambs and fertility of ewes in this production environment.     

甘肃高山细毛羊枯草季放牧与暖棚舍饲饲养对比试验

枯草期选甘肃高山细毛羊成年母羊180只,后备母羊38只,羔羊40只,进行为期171 d的放牧与舍饲对比试验。结果表明:试验组(暖棚舍饲)平均每只成年母羊、后备母羊和羔羊体质量分别增加5.1、9.8和6.9 kg,增幅为:11.72%、30.81%和32.86%;对照组(放牧)每只成年母羊、后备母羊和羔羊体质量分别平均下降7.3、5.0和1.0 kg;试验末,试验组成年母羊和后备母羊体质量极显著高于对照组(P0.01),试验组羔羊体质量显著高于对照组(P0.05)。羊毛长度试验组成年母羊、后备母羊和羔羊羊毛每只分别平均增长3.9、3.8和2.7 cm,试验组成年母羊和后备母羊比对照组提高10.4%和16.0%,羔羊比对照组降低11.2%,试验组和对照组差异不显著(P0.05)。试验组各年龄段产羊毛量分别达5.24、4.56和3.79 kg,比对照组分别提高60.24%、73.38%和49.80%,差异极显著(P0.01)。试验组纯收入分别为成年母羊5.35元/只,后备母羊45.65元/只,羔羊59.57元/只,对照组由于掉膘损失严重,成年母羊和后备母羊分别损失28.32和13.05元/只,羔羊收益29.3元/只。