The Effects of Ovine Lentivirus Infection on Some Productive Aspects in a Sardinian Sheep Flock from Italy

The effects of ovine lentivirus infection on the fat, protein and lactose concentrations on the somatic cell counts in ewes' milk, on milk production and on the birth weight and growth of lambs were studied in a flock of Sardinian sheep from central Italy. Data on 61 lactations of ewes positive to both the agar-gel immunodiffusion test and an enzyme-linked immunosorbent assay were compared with those on 46 lactations of seronegative ewes. Confounders such as parity, age, lactation length, litter size, and the sex of the lambs were considered. None of these traits seemed to be negatively influenced by the infection     

Improving feeding systems for sheep in a Mediterranean rain-fed cereals/livestock area of Morocco

In rain-fed cereal-producing areas of Morocco, stubble and straw from barley and wheat and forage grazed from fallow lands are important feeds for sheep. Supplementation to maintain BW of ewes pregnant while grazing stubble, methods to improve utilization of straw, annual forage legumes to complement grazing of fallow land, and by-product feeds in diets for weaned lambs have been tested in collaborative research trials. Pregnant ewes grazing cereal stubble for 10 to 12 wk at a modest stocking rate and unsupplemented, or at a heavier stocking rate and supplemented after 5 wk, gained about 3 kg; most of the gain occurred in wk 1 to 4 due to intake of residual scattered grain. Following the stubble-grazing period (coincident with late gestation), straw plus an energy supplement alone resulted in low lamb birth weight and survivability. Urea treatment increased N content of straw and holds potential. After the onset of winter rains, self-reseeding annual legume (Medicago spp.) pastures allowed lactating Timahdit ewes to gain 4 kg during 90 d postpartum. Their suckling lambs gained 260 g/d, thus doubling the weight of lamb weaned per ewe compared with those grazing unimproved fallow. Confined growing lambs fed diets with 40% sugarbeet pulp or 20% carob meal gained more than 200 g/d, reducing the time needed to reach market weight. These results demonstrate that marked improvements in performance and efficiency of sheep in Mediterranean rain-fed cereal/livestock systems are possible using locally available resources.     

Effects of energy supplementation on lamb production of Javanese thin-tail ewes

A 3-yr study was conducted in North Sumatra, Indonesia, as part of an evaluation of the feasibility of integrating sheep and rubber production. The objective was to evaluate the effects of increasing energy supplementation on reproduction and other performance criteria of Javanese Thin-Tail sheep grazing volunteer forages under 8- and 14-yr-old rubber trees. The control group was unsupplemented. The medium group was supplemented with high-energy feeds at 1% of the flock body weight, with the low and high groups receiving 60% or 140% of the daily energy provided by the medium group diet. Supplements provided 1.2 g protein per kilogram BW. There were 158 lambs born to the 152 ewes in the 1st year of the study. Preweaning mortality rates of lambs were reduced (P less than .01) with supplementation (45 vs 12, 3 and 12% for the control, low, medium and high groups, respectively). During the 3 yr, litter size was higher (P less than .01) in the high group (1.33, 1.31 and 1.34 vs 1.71 for ewes on the four respective diets). Observed repeatability of litter size of individual ewes in all treatment groups for the first three parities was higher (P less than .01) than would be expected if litter size were a random event. Of the lambs born in the 1st yr, kilograms of lamb weaned per ewe joined were 3.1, 7.8, 7.3 and 9.8. At prevailing prices, only the high supplement level was profitable compared to the control. For the high group, the added return from the sale of lambs born the 1st yr was 120% of the added cost of supplementing the ewes until all the lambs were weaned (15 mo). Response of sheep to the high level of energy supplementation, especially with regard to litter size, indicates that supplementing sheep grazing in rubber plantations at a high level can be profitable.     

The effect of mixed or sequential grazing of cattle and sheep on the faecal egg counts and growth rates of weaned lambs when treated with anthelmintics

An experiment was conducted over two successive years (2002 and 2003) to investigate the effects of grazing improved permanent pasture (mainly perennial ryegrass/white clover) by cattle or sheep, either sequentially or mixed, on the faecal egg counts and growth rates of weaned lambs when treated with anthelmintics. The grazing season was divided into two parts, May-July then July-October, relating to the pre- and post-weaning of the lambs. Four grazing regimes, replicated three times, were compared: (1) sheep only from May to October (SS); (2) cattle May to July followed by lambs until October (C/S); (3) cattle and sheep May to July followed by lambs until October (C+S/S); and (4) cattle and sheep May to July followed by cattle and lambs until October (C+S/C+S). Sward height was maintained at 6 cm using a "put and take" stocking system. At weaning, lambs were weighed and treated with an anthelmintic (0.08% ivermectin drench, Oramec) before being allocated to plots. They were then weighed and drenched every 28 days until the end of the experiment (Day 84). Faecal egg counts (FEC) were measured in all lambs immediately prior to each anthelmintic treatment. In 2002 and 2003, there were differences between the groups in FEC, with the SS lambs having the highest values and C/S lambs the lowest (P<0.01). There were also differences in the rate of liveweight gain of the lambs in each of the study years: for this parameter SS lambs had the lowest growth rate but the fastest growth was in C+S/C+S lambs not C/S lambs (P<0.01), indicating that these differences were due to factors other than parasite infection. Overall, sequential grazing of pastures with cattle then sheep reduced the faecal egg counts in lambs regularly treated with anthelmintics when compared with lambs grazing in mixed systems with cattle and sheep or with sheep only systems, however, the highest growth rates were observed in lambs in the mixed cattle/sheep grazing system throughout.     

Towards the eradication of Haemonchus contortus from sheep flocks in Sweden

Previous studies have shown that between-year transmission of Haemonchus contortus in Swedish sheep flocks is almost entirely as over-wintered populations within housed animals, and not on pasture. This suggests that eradication of this parasite is a realistic possibility. Thus, two sheep farms with a history of H. contortus infection on the Swedish island of Oland were selected for study. During the winter housing period of 2003/2004 all ruminants (sheep and cattle) on both farms were treated with ivermectin. Monitoring by faecal egg counts and infective larval differentials of ewes and lambs for the subsequent two grazing seasons, together with total abomasal worm counts of 10 lambs from each farm at the end of the first grazing year, showed that this objective was achieved.     

The dynamics, prevalence and impact of nematode infections in organically raised sheep in Sweden

A three-year survey (1997-99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei. T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs.     

Reservoirs of Staphylococcus aureus in meat sheep and dairy cattle

The objective of the study was to investigate reservoirs and transmission of S. aureus in ewes and lambs in 3 meat sheep flocks. Repeated sampling of milk, teat skin, nasal- and vaginal mucous membranes was performed and samples were analysed for S. aureus. For comparison, samples were also collected from cows and young heifers in 3 dairy cattle herds. Selected isolates were compared by pulsed-field gel electrophoresis (PFGE). S. aureus was detected in 8 (1.5%) of 520 milk samples from ewes and in 38 (6.4%) of 588 milk samples from cows. From body site swabs, S. aureus was found in 394 (32.6%) of 1208 samples from sheep and in 67 (16.0%) of 420 samples from cattle. The proportion of S. aureus-positive nasal swabs from ewes and cows were 56.7% and 13.9%, respectively. From lambs, 58.2% of the nasal swabs were S. aureus-positive. In each flock, one S. aureus pulsotype predominated. Identical S. aureus pulsotypes were found in milk and from body sites. Paired S. aureus isolates from the nasal cavity of (i) ewes and their lambs, (ii) twins and (iii) from repeated swabs of individual ewes were compared by PFGE, and in the majority of cases the two isolates were identical. The results contribute new knowledge indicating frequent transmission of S. aureus between the dam and her lambs and within animals in a flock. In contrast to cattle, S. aureus is frequently present in the nose of sheep which may represent the primary reservoir of S. aureus in sheep flocks.     

Effect of farm characteristics and practices on hygienic quality of ovine raw milk used for artisan cheese production in central Italy

A survey on ovine dairy farms directly transforming own‐produced milk, in the Italian Marche region, was carried out to assess flock and milking practices that may influence milk hygienic‐sanitary conditions. A census survey established that 24 dairy farms were located in this region. Bulk milk samples were collected throughout the milking period in each dairy farm in 2013. Analyzed variables were: (i) chemical parameters such as fat, protein and lactose content, dry matter and pH; and (ii) total bacterial (TBC) and somatic cell counts (SCC). Chemical parameter values were in agreement with published data while, geometric mean (GM) log₁₀ SCC was 5.91 and TBC GM was 57 978 colony forming units/mL, in compliance with Eropean Union criteria. A positive correlation was found between SCC and TBC when GMs of all farm data were considered (Spearman's rho = 0.7925; P = 0.0001). Statistical analysis did not show significant correlation between SCC or TBC GM and dairy farm principal characteristics. Although SCC levels detected in the present study should suggest the need to implement mastitis control programs, Marche's dairy sheep flocks revealed a good hygienic condition level. This is an important aspect in implementing safety for end users of the final product.     

Effectiveness of photoperiod stimulation on reproductive performance of sheep housed continuously indoors on an accelerated breeding schedule.

Over five breeding periods, the reproductive performance (fertility, prolificacy and fecundity) of three strains of sheep housed continuously indoors was measured. The sheep were maintained as two separate flocks, A and B, with similar genetic background on an eight month accelerated breeding schedule under one of three lighting regimes, abrupt, contracted or constant, to induce ovarian activity. Overall fertility to one estrus was 59%. For flock A, fertility was greatest under the contracted lighting regime and lowest under the constant lighting regime; the opposite was true for flock B. Among the three strains, fertility was lowest for the Dam 2 strain in flock A. Prolificacy averaged 1.8 lambs per ewe lambing and was similar under each of the three lighting regimes. Fecundity (averaging 106%), the number of lambs born per 100 ewes exposed to rams, generally followed the pattern of fertility.     

Breeding for resistance to mastitis in United Kingdom sheep, a review and economic appraisal

Mastitis is a problem in the sheep industry, and its incidence varies widely with how it is recorded, the breed of sheep and the farm. Virtually all the published information about the genetics of mastitis refers to dairy breeds of cattle and sheep, and there is little information for meat sheep breeds. Many dairy breeding programmes worldwide use the somatic cell count (scc) in milk as an indicator of resistance to clinical and subclinical mastitis, but it is difficult to measure in meat sheep breeds. Molecular genetic technologies may therefore be a more practical way to assess susceptibility to mastitis. This paper reviews the genetics of mastitis and considers the opportunities for breeding for resistance to mastitis, with particular reference to sheep. In addition, to investigate the potential economic effects of mastitis in a purebred sheep population, a computer model of flock dynamics was developed. By making a modest set of assumptions about the key farm parameters that influence lowland sheep production, the model showed that breeding for resistance (or other control methods), if it could reduce the risk of contracting mastitis by 10 per cent, would be worth pounds 8.40 per ewe, equivalent annually to pounds 2.7 million for the purebred sector of the Texel breed alone.     

Epidemiologic approach to the control of sheep nematodes

Epidemiologic approaches to parasite control, with reduced reliance on the use of anthelmintics, were studied in 6 groups of weaned lambs and 4 groups of suckling lambs grazing fertilized pastures. Strategies tested included prophylactic treatments in the spring, provision of safe pastures, treat-and-move strategies, and winter (prelambing) treatment of ewes. Suppressive treatment with a non-benzimidazole drug was used as a production yardstick against which the epidemiologic approaches were judged. Suppressive treatment with a benzimidazole drug was used to determine the drug resistance status of the flock. The success of each strategy was evaluated by measurements of body weight, wool growth, fecal egg counts, pasture larval counts, and total worm burdens. Prophylactic treatments in the spring were just as effective as suppressive treatments throughout the entire grazing season and resulted in significant (P less than 0.001) increases in weight gain. Effective parasite control also was obtained by moving ewes and lambs to safe pastures (low infectivity) in May, and resulted in significant (P less than 0.001) increases in weight gain. A treat-and-move strategy led to significant (P less than 0.001) increases in weight gain until September, but then a loss of weight in October, suggesting the need for a double treat-and-move strategy in the case of late-marketed lambs. The value of winter (prelambing) treatments for ewes also was demonstrated. Suppressive treatments with a benzimidazole drug confirmed the presence of benzimidazole-resistant nematodes.     

基于Meta分析的母羊泌乳模型构建及泌乳性能预测

母羊泌乳量不仅关乎母羊自身营养需求,也是影响羔羊生长发育的重要因素,准确预测母羊泌乳量在母羊和羔羊精准饲养中具有现实意义。本文利用方差倒数Meta分析方法研究母羊泌乳曲线模型及泌乳参数,并对其泌乳性能进行预测。分别在Web of Science、CNKI等文献数据库中检索母羊泌乳曲线及影响因素的相关文献,依据纳入标准筛选和提取泌乳曲线相关参数,采用方差倒数Meta分析方法进行合并,综合评估母羊泌乳曲线及其影响因素。共纳入文献22篇,提取数据98条。结果显示：山羊泌乳曲线模型为y=0.943 8t^{0.359 9}e⁽(-0.008 5t)),绵羊为y=0.677 2t^{0.349 4}e⁽(-0.014 0t)),乳用山羊为y=1.143 7t^{0.318 7}e⁽(-0.008 0t)),非乳用山羊为y=0.419 0t^{0.468 1}e⁽(-0.011 8t)),乳用绵羊为y=0.796 8t^{0.256 2}     

The epidemiological control of nematodes in New England lambs

Epidemiological control of nematodes in weaned lambs in New England was investigated over three grazing seasons (n = 58, n = 52 and n = 62 lambs, respectively). Spring prophylactic treatment, clean pasture and mid-summer treat-and-move to hayfield strategies were compared to traditional fall treatments (control). In these studies when lambs were weaned prior to grazing, the most abundant nematodes were Nematodirus sp. Under these conditions, where only low levels of Haemonchus contortus were present, no significant improvement in body weight gain was observed for the epidemiologic approaches compared to the traditional fall treatments. No untreated control was used, and fecal egg counts and pasture larval counts indicate low total worm burdens with a controllable fall rise in pasture infectivity. These results indicate the importance of hypobiosis for the survival of H. contortus and suggest that weaning lambs prior to grazing can be an effective epidemiological control practice.     

Control of ovine gastrointestinal helminthiasis by the use of 'clean' grazing and strategic dosing in the field

Despite the widespread adoption of clean grazing systems in lowland sheep flocks, detailed parasitological investigations had not previously been carried out on such flocks. A trial was therefore conducted on two commercial flocks: a traditional permanent pasture flock (A) and one operating a system of clean grazing (B), and on an East of Scotland College flock (C) which had operated a clean grazing system for eight years. Ewe and lamb worm egg output, pasture larval levels and lamb liveweight gains were monitored and tracer lambs were grazed during July and August on each farm. Under clean grazing conditions on farm C all parasitological parameters were lower than on both commercial farms. However, in the commercial flocks comparable contamination was evident from midsummer onwards and tracer lambs grazed during August on farm B had significantly greater worm burdens than on the other two farms. The differences observed between the flocks were thought to be due to greater residual contamination by overwintered larvae in both commercial flocks while the higher worm burdens in August on farm B probably resulted partly from incomplete control of the periparturient rise in ewe faecal egg output and partly to autoinfection of the lamb crop. It was concluded that farm C grazing was the cleanest. Considerable contamination was present on farm A while farm B occupied an intermediate position which resulted in considerable worm burdens in lambs grazing during the latter part of the season.     

The epidemiology and pathogenic significance of haemonchosis in a merino flock in East Africa

The epidemiology of H. contortus was studied for 21 months in 80 set-stocked Merino ewes and their grazing in an endemic area in Kenya. Observations included faecal egg counts (weekly), worm burdens (monthly), haematological indices and clinical signs. The levels of infective larvae on the pasture were estimated using tracer sheep.The classical acute form of haemonchosis was seen with equal intensity in both ewes and lambs during periods of high rainfall and self-cure was confirmed as a flock phenomenon which occured simultaneously on one occasion in sheep of all ages.Not previously recognised were the uniformity of the faecal egg counts in both ewes and lambs over long periods when the worm burdens fluctuated greatly, the marked decrease in worm burdens without the occurence of classical self-cure during periods when the intake of infective larvae was low, and the inverse relationship between the individual worm-weight and the total worm population. It was also concluded that one of the most significant features of haemonchosis is not the acute syndrome so characteristically associated with the disease, but the fact that a moderate infection of a few hundred worms persisting over a period of several months will produce chronic anaemia and, ultimately, severe loss of bodily condition and deathes in ewes and lambs grazing on poor quality pasture.     

Establishment of a maedi-visna-free flock after the purchase of infected sheep

Maedi-visna (MV) infection was detected in a cohort of 68 purchased ewes, one of several groups of sheep introduced to a farm after the previous stock had been culled with suspected foot-and-mouth disease in 2001. Except for short periods totalling six to seven weeks when the sheep co-grazed with 13 ewe lambs and ram lambs, the infected cohort was kept separate from other sheep on the farm over a total of 21 months. During this period two crops of lambs were reared from the infected ewes. All the lambs were fattened and killed, and all ewes were culled after the second crop of lambs had been weaned. Subsequent serological testing of the remaining sheep on the farm confirmed the elimination of MV infection from the flock, leading to its acceptance in the Maedi Visna Accreditation Scheme of the Scottish Agricultural College's Sheep and Goat Health Schemes.     

A comparison of somatic cell count between organic and conventional dairy cow herds in West Germany stressing dry period related changes

Mastitis is one of the major threats to animal health and thus to productivity in all dairy farming systems. Previous studies of organic dairy herds have indicated better udder health in organic herds, as compared to conventional herds but opposite results have also been reported. In view of the great implications that the dry period (DP) has on udder health, we aimed to compare milk performance data between organic and conventional dairy herds by specifically addressing the relation of somatic cell counts in milk (SCC) before and after the DP. On 68 farms (35 organic, 33 conventional) in Western Germany individual cow and herd production data were recorded next to data on SCC (herd, individual) between June 2002 and June 2004. For data analysis, SCC values > 150,000 cells/mL were defined as indicative for disorders of udder health.     

Comparative study of gastrointestinal helminthiasis in sheep on 'clean' grazing and permanent pasture under field conditions

An investigation of sources of helminth infection was carried out on three flocks: a traditional permanent pasture flock (A), one operating a 'clean' grazing system (B), and an East of Scotland College flock (C) which had operated a clean grazing system for nine years. Ewe and lamb worm egg output and pasture larval levels were recorded and tracer lambs were grazed during July and August on each farm. Considerable contamination was present on farm B fields compared with farms A and C, which resulted in higher worm burdens in late summer in farm B tracer lambs and lower weight gains. The main source of this infection was thought to be ewe periparturient egg output, as 21 per cent of ewes had positive worm egg counts over the lambing period. Differences in management practices between farms B and C, eg, earlier stocking of farm B fields, were also considered contributory factors.     

不同品种受体对绵羊胚胎移植效果及羔羊早期生长性能的影响

旨在探讨以小尾寒羊和蒙古羊作为受体时,二者的胚胎移植效果及所产羔羊的早期生长性能之间的差异。选用南非肉用美利奴羊(n=11)和澳洲白绵羊(n=110)作为供体,以小尾寒羊(n=196)和蒙古羊(n=504)作为受体;对供体母羊进行超数排卵以及人工授精处理,记录供体母羊的收集胚胎总数和可用胚胎数,计算平均每只羊收集的可用胚胎数以及胚胎合格率;对小尾寒羊和蒙古羊进行同期发情及胚胎移植处理,记录受体母羊的产羔数,计算繁殖率;计算并比较不同受体母羊所产羔羊的平均初生重、成活率以及70日龄断奶羔羊数、70日龄断奶重、平均日增重、平均每只母羊提供的断奶羔羊数。结果表明,从供体母羊中共获得可用胚胎549枚,平均每只羊收集可用胚胎4.54枚,胚胎合格率为82.56%;利用胚胎移植技术,移植受体母羊529只,所产羔羊240只,平均繁殖率为45.37%;小尾寒羊的发情率和繁殖率明显高于蒙古羊;共获得70日龄断奶羔羊211只,羔羊成活率为87.92%,平均日增重为280.00g;小尾寒羊和蒙古羊所产的羔羊初生重没有显著差异(P>0.05),小尾寒羊所产羔羊的70日龄断奶重和平均日增重分别极显著(P<0.01)和显著(P<0.05)高于蒙古羊,而蒙古羊所产羔羊的成活率显著高于小尾寒羊(P<0.05);平均每只小尾寒羊母羊可提供的断奶羔羊数(0.42只)略高于蒙古羊(0.39只),小尾寒羊作为胚胎移植受体略具有优势。综合分析表明,在内蒙古兴安盟地区小尾寒羊和蒙古羊均可以作为胚胎移植的受体来使用。