Intake of trichostrongylid larvae by goats and sheep grazing together

SUMMARY Cashmere goats and Merino sheep were grazed together at 7.5 animals per ha on annual rye grass and clover pasture in southern Victoria, a winter rainfall area. Intake of parasitic larvae was measured in oesophageal extrusa samples collected from 2 animals of each species, 4 times in one week, on 7 occasions between mid-March (autumn) and mid-June (winter). Pasture contamination with larvae was measured at the same times. The number of larvae per kg of green grass was lower than on green clover; the most heavily contaminated portion of the pasture was the mat of dead herbage on the ground. The diet selected by goats contained more green grass and dead herbage and less clover that that of sheep (P < 0.01). Goats ingested 643 infective trichostrongylid larvae per kg dry matter intake (DMI) versus 274 per kg DMI for sheep in autumn, increasing to 1892 versus 1143 in early winter. The heavier trichostrongylid burdens of goats compared with sheep, when grazed together, are due in part to greater rates of infection consequent on different grazing patterns as well as greater susceptibility to infection.     

Grazing behavior of horses on pasture: Predisposition to strongylid infection?

This study was designed to determine how the behaviors of horses on a fenced-in pasture in the northeastern United States may contribute to infection by Strongylus vulgaris. The infective stages of strongylid parasites of horses develop in the feces, and they must be ingested for infection to occur. Domestic horses are thought to be coprophobic, and to avoid grazing in areas contaminated with their feces. ^1,2 In this study, nine Standardbred colts were observed on two pastures three times a week during two observation periods (January, 1995 and February through mid-March, 1995). Nine adult Standardbred mares and geldings were also observed on the same pastures during one observation period from April through mid-May, 1995. On each pasture, the roughs (areas of group defecation associated with long grass), lawns (short-cropped grass) and bare areas (where hay was fed in racks), were mapped. Grazing occurred equally on roughs, lawns, and bare patches of the pasture in two of the three observation periods (January and April/May). In the February/mid-March observation period, most of the grazing activity occurred on the bare areas, where hay was provided, but there was still grazing in the roughs. Defecation and urination activities occurred at similar frequencies in all areas of the pastures during all observation periods. These data suggest that horses kept at high grazing intensities will graze near feces in the roughs, and will defecate in the “grazing” areas. It was also determined that the infective larvae of S. vulgaris are attracted to horse feces, but show no responses to grass, in laboratory chemical migration assays. These data suggest that the parasites may not migrate from the feces to the grass as part of their transmission strategy as previously reported. Thus, parasite infection may be occurring when horses graze in the roughs or near feces in the lawns and bare areas, and pasture management strategies for controlling these parasites may be most effective if focused on reducing the infective larvae present on the pasture.     

基于高寒草地放牧系统次级生产力的优化放牧强度研究

依据小嵩草（Kobresia parva）高寒草甸和垂穗披碱草（Elymus nutans）/星星草（Puccinellia tenuflora）高寒混播人工草地牦牛放牧系统、紫花针茅（Stipa purpurea）高寒草原藏系绵羊放牧系统中草地次级生产力（家畜增重）的试验数据,构建了放牧家畜个体增重与放牧强度之间的模型：Y=a-bX（b>0）,以此为基础确定了单位面积草地次级生产力（家畜增重）与放牧强度之间的数学模型：Y=aX-bX²（b>0）;计算出各放牧系统最大生产力放牧强度：高寒草甸冷季和暖季草场分别是1.68头·hm^-2和2.52头·hm^-2,高寒人工草地牧草生长季为7.23头·hm^-2,高寒草原冷季、暖季和全年连续放牧草场分别是4.33,6.45,2.36只·hm^-2。     

The evaluation of endophyte toxin residues in sheep fat

Abstract

AIM: To monitor changes in concentrations of lolitrem B and epoxy-janthitrems in the fat of sheep grazing perennial ryegrass infected with wild-type- and AR37-endophyte, respectively, during the time of year when ryegrass staggers would be expected to be observed.

METHODS: Ten 5-month-old lambs with no previous exposure to endophytes were grazed on either wild-type (containing lolitrem B, n = 5) or AR37 (containing epoxy-janthitrems, n = 5) endophyte-infected perennial ryegrass (Lolium perenne L.) pastures between October 2008 and June 2009. Animals were regularly assessed for ryegrass staggers using the Keogh scale (0 = no signs, 5 = severe tremors). When a score of > 3.5 was observed animals were removed from the treatment pastures for 1 month. Fat biopsy samples were taken from each animal at approximately monthly intervals and analysed for endophyte metabolites using high performance liquid chromatography (HPLC) methods developed during this study. Regular herbage samples were also taken and concentrations of endophyte metabolites measured.

RESULTS: Efficient and reproducible methods to analyse both lolitrem B and epoxy-janthitrems in fat were developed. Concentrations of lolitrem B and epoxy-janthitrems in herbage and in sheep fat increased from late November to peak in mid-February. Ryegrass staggers was observed in both groups of sheep at this time. Following 1 month of grazing non-infected pasture mean concentrations in fat of lolitrem B decreased by 43% from 61.8 to 35.3 ppb, and of epoxy-janthitrems by 38% from 1032.0 to 639.5 ppb. Maximum concentrations in herbage of epoxy-janthitrems (35.7 ppm) were higher than of lolitrem B (3.4 ppm), but signs of staggers were less severe in sheep grazing pasture containing the former compared with the latter (median Keogh scores in late February were 2 and 3, respectively), consistent with epoxy-janthitrems being low potency toxins.

CONCLUSION: This study demonstrated that concentrations of epoxy-janthitrems and lolitrem B in sheep fat increased quickly during the initial phase of the study when concentrations in pasture increased, and decreased when animals were removed from pastures containing these compounds. These data will be used in the risk assessment of the endophyte metabolites.     

Grazing by Steers at Different Sward Surface Heights on Extensive Pastures: A Study of Weight Gain and Fat Deposition

Live weight gain of steers grazing at three different target sward heights, Low (3-6 cm), Medium (6-10 cm) and High (>10 cm), together with carcass fat deposition, were studied during two grazing seasons. Sward height was measured with a sward stick. The grassland consisted of seminatural grazing areas mixed with previously cultivated areas. Animals grazed continuously with small adjustments in animal numbers (year 1) or pasture area (year 2) to maintain sward height within the target for each treatment. The recorded average sward heights were 4.7, 6.8 and 11.1 cm for pastures on treatments Low, Medium and High, respectively. The animals weighed approximately 440 kg at the start of the grazing season and went directly from pasture to slaughter at the end of the experiment. No differences between years were found and data from both years were thus pooled, giving a total of 50 steers of the Swedish Red and White breed in the data set. Over the whole grazing season, the average daily live weight gain of animals on treatment Low (0.43 kg day     

Clinical, pathological and epidemiological findings in three outbreaks of ovine protozoan myeloencephalitis

Ovine protozoan myeloencephalitis is a disease of sheep associated with the apicomplexan protozoan Sarcocystis tenella. This paper describes the clinical, pathological and epidemiological findings in three affected flocks from a well-defined geographical area. Clinical signs were restricted to sheep under one year old in their first winter and were first observed at least 42 days after they had been moved off the hill grazing areas to low ground pasture, or after they were given conserved forage. The findings are discussed in relation to the timescale of the life cycle of S. tenella and it is suggested that clinical disease was precipitated by the change from a low level of exposure to infection on the hill to a high level of exposure through contaminated pasture or forage. Possible preventive strategies are discussed.     

Gastrointestinal parasites in young cattle in Norway

Field experiments were carried out for three consecutive years to study the influence of gastrointestinal nematodes in young cattle during their first grazing season. Free-living stages of Ostertagia ostertagi and Cooperia oncophora were found to survive the winter in the pasture in sufficient numbers to cause reduced weight gain and clinical disease, including deaths, in the calves. The symptoms were most pronounced during the first half of the grazing season.The mean weight gain of calves on parasite-free pastures was 48.3, 15.5 and 31.2 kg above those on contaminated pastures during the 3 years.Calves grazing contaminated pasture from the spring onwards, treated with thiabendazole and moved to aftermath in July, showed significantly better weight gain during the last part of the grazing season than calves which remained on the same contaminated pasture. It was, however, suggested that the better grazing conditions were the main cause of the improved weight gain on aftermath.     

Heat energy for growing goats and sheep grazing different pastures in the summer.

Angora goat, Spanish goat, and Suffolk x Rambouillet sheep wethers (20 of each type; 30.4+/-.57, 31.3+/-.93, and 32.4+/-1.08 kg BW for Angora goats, Spanish goats, and sheep, respectively) were used to investigate influences of animal type and two grass-based pasture treatments on heat energy during summer grazing (mid-August through September in Oklahoma). The improved pasture treatment consisted of .7-ha paddocks primarily of Old World bluestem and johnsongrass, whereas the native pasture treatment entailed 10.8-ha paddocks dominated by big and little bluestems and indiangrass. Grasses were 95 to 100% of diets for the improved pasture treatment and 71 to 95% for the native pasture treatment; forbs were 2 to 25%, and shrubs were less than 4% of diets for the native pasture treatment. Metabolizable energy intake was similar (P > . 10) between pasture treatments but differed (P <.01) among animal types: 79, 99, and 113 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively; SE 7.1. Heat energy estimated via CO2 entry rate was affected by pasture treatment ( P = .08) and animal type (P < .001): improved pasture treatment 109, 132, and 151 kcal/(kg(.75) BW.d); native pasture treatment 126, 138, and 163 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively. Likewise, daylight grazing time was greater (P = .04) for the native than for the improved pasture treatment and differed (P < .01) among animal types: improved pasture treatment 5.3, 4.7, and 6.7 h; native pasture treatment 6.0, 5.7, and 8.1 h for Angora goats, Spanish goats, and sheep, respectively. In conclusion, heat energy during summer grazing of grass-based paddocks was less for goats than for sheep, and animal type can affect the increase in heat energy as energy intake and grazing time increase.     

Area use of two sheep breeds in contrasting summer alpine grazing environments in southern Norway

In Norway, approximately 2 million sheep are released for summer grazing onto highly heterogeneous outer-fields. The crossbred Norwegian White Sheep (NWS) is dominating, whereas the lighter short-tailed gregarious Spælsau (SP) is the second most abundant of the total Norwegian sheep population. We fitted 51 ewes with GPS collars in two contrasting alpine environment, Spekedalen (poor pasture) and Brathøa sauhavnelag (rich pasture), during the summer grazing seasons 2013 and 2014. We modelled breed differences in summer area use and found no significant effect of breed or pasture quality. No breed?* pasture interaction was found. Information of pasture quality and breed characteristics is vital to understand the resource–animal interplay and may prove important for sheep management.     

Short‐term effects of cattle‐to‐sheep ratio and stocking rate on patch grazing in sour grassveld

Abstract

The short‐term effects of stocking rate (AUE ha^?1) and cattle‐to‐sheep ratio on the extent and severity of patch grazing and on patch size were evaluated. The extent of patch grazing was proportional to stocking rate, and livestock species had a small but significant effect. Patch size was also a function of stocking rate. Cattle and sheep had similar effects on patch size distribution when stocked at the same number of AUE ha^?1. The severity of grazing within a patch was influenced by both stocking rate and cattle‐to‐sheep ratio. Recommendations that cattle should be grazed together with sheep and that cattle should be in greater proportion (in terms of AUE ha^?1) than sheep, which are aimed at limiting the severity of grazing by sheep, are supported. However, severe grazing within patches is an inevitable consequence of sheep grazing irrespective of the stocking rate or cattle‐to‐sheep ratio applied.     

The epidemiology of fasciolosis in Papua New Guinea

Fasciola hepatica metacercariae were present on pasture throughout the year at the trial site. The highest infection rate in trial sheep occurred in the first year after the beginning of the wet season, in December/January, when contamination of the pasture was maintained by other sheep. Variation in rates of infection in consecutive years was linked to differences in grazing pressure and to a change from sheep to cattle as accompanying grazing stock. A minimum precipitation of 125 mm over 4 consecutive weeks appears to be necessary for infected snails to move from their normal habitats and to contaminate wet pasture with cercariae. Infection of sheep can occur during a dry season if pasture has permanent seepage sites or swampy areas where infected snails can remain active and continue to liberate cercariae.     

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content

Aim. To obtain information on serum and liver vitamin B₁₂ and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B₁₂ in young dairy cattle when grazing pasture of low cobalt content.

Methodology. Forty dairy cattle (12 Friesian, 14 Friesian × Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for Vitamin B₁₂ concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations.

Results. No weight gain response occurred to Vitamin B₁₂ supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver Vitamin B₁₂ concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B₁₂ concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation.

Conclusion. Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum Vitamin B₁₂ concentrations at which growth responses to Vitamin B₁₂ or cobalt supplementation are likely under New Zealand pastoral grazing conditions.     

放牧强度对高寒草地产草量及羊体质量增加的影响

以托云牧场高寒草地为研究对象,通过设置3个放牧样地,一个对照样地,研究不同强度放牧对草地地上生物量的影响以及在不同放牧压力下羊体质量增加的效果。结果表明,1）托云牧场是以银穗草（Leucopoa albida）、羊茅（Festuca arioides）、点地梅（Androsace umbellata）和棘豆（Oxytropis falcatae）为优势种的高山草地;2）高寒草地地上生物量较低,禁牧区7月地上生物量（干物质）仅830 kg·hm-2;3）放牧活动对地上生物量有较大影响,重度放牧能显著降低牧场地上生物量;4）以羊体质量增加值为评价指标,该高寒牧场在载畜量为1.05羊单位·hm-2时能获得较好的体质量增加效果。     

Seasonal influence on diet selection of sheep grazing a weedy dryland lucerne pasture

The experiment was conducted to determine the seasonal effects on the availability, chemical composition and digestibility of a grazing dry-land lucerne pasture, as measured on samples either collected by hand or with oesophageally fistulated (OF) sheep. The pasture was monitored monthly for a period of thirteen months. An overall mean amount of 647 kg DM ha^?1 of material was monitored during the experimental period. Lucerne, as a percentage of the total DM availability was relatively low (approximately 19%), probably due to the preference of sheep to select lucerne in spite of the other available material. Both the crude protein (CP) content and the organic matter (OM) digestibility of the samples showed a seasonal tendency with higher values during the winter and lower values during the summer. Mean OM, CP, organic matter digestibility (OMD), acid detergentfibre (ADF) and neutral detergent fibre (NDF) contents of 91.7%, 10.7%, 57.5%, 47.1% and 74.0%, respectively, were obtained with hand-clipped samples, while the corresponding composition of samples collected by OF sheep was 83.1%, 21.0%, 64.7%, 38.2% and 58.4%, respectively. The sheep were able to select forage samples with a higher CP content than those collected by hand throughout the year. This was, however, not the case with the organic matter digestibility of the samples during the growing season July to October. The CP content of fistula extrusion samples (f) could be predicted from hand-clipped samples (h) from the linear relationship, CP_f = 10.51 + 0.97CP_h (r = 0.59). The study provided figures on the chemical composition and digestibility of dryland lucerne pasture at grazing in a Mediterranean environment.     

Acute coenurosis of dairy sheep from 11 flocks in Greece

Abstract

CASE HISTORY: A syndrome of acute neurological dysfunction with increased mortality was observed in lambs of 10 dairy sheep flocks and adult animals in one flock in Central and Northern Greece. Each farmer completed a questionnaire regarding the management and feeding of their flocks. In seven of the 11 flocks the affected animals were grazing pasture, while in the remaining four flocks (5, 8, 9, 10) the animals were fed alfalfa hay (Medicago sativa) and concentrates indoors. A follow-up study of the affected flocks was conducted during the next 12 months.

CLINICAL FINDINGS: Of 42 sheep with acute coenurosis that were examined, the most prominent neurological abnormalities were ataxia, depression, blindness, scoliosis, coma and dysmetria. Except for the four sheep that were comatose, all other animals had normal body temperatures and their appetites remained normal or were slightly decreased. Haematological findings of 15 examined sheep were within normal limits. The affected sheep were subject to euthanasia. A histopathological examination was performed in 13 cases. Faecal samples from dogs associated with these flocks were negative for taeniid infections. During the following 12 months cases of chronic coenurosis in these flocks were observed.

PATHOLOGICAL FINDINGS: In the 42 animals that were necropsied, the main gross findings were cystic formations between 0.5–1 cm in diameter with translucent walls that were seen lying free on the leptomeninges or partly penetrating the brain tissue, sterile microabscecess and brain necrosis. Histopathological evaluation of tissue sections of 13 brains showed multifocal purulent or pyogranulomatous meningoencephalitis, accompanied by eosinophilic infiltrations. No bacteria were isolated following bacterial culture of brain tissue Parasitological examination of the cysts from five cases revealed whitish specks on the transparent cyst wall and germination membrane representing the scolices.

DIAGNOSIS: Acute coenurosis was diagnosed in all cases studied.

CLINICAL RELEVANCE: Acute coenurosis can be one of the causes of acute encephalopathy mainly in lambs, but also in adult sheep. This condition is incurable, but can be controlled by changing the feeding regime. Cases of chronic coenurosis may be seen a few months later in the same flock.     

The ranging behaviour and habitat use of rabbits on farmland and their potential role in the epidemiology of paratuberculosis

Grazing herbivores avoid grass swards contaminated with faeces as the ingestion of faeces is a common route of micro- and macro-parasite transmission. The recent novel finding that herbivores do not avoid grass swards contaminated with rabbit faeces suggests that disease risk posed to herbivores by rabbits is determined by rabbit ranging and excretory behaviour. Using as a case study rabbits and the risk Mycobacterium avium sub-species paratuberculosis (M. a. paratuberculosis) poses to cattle, the interaction between rabbits and grazing pasture was studied on an infected farm in the east of Scotland in spring and autumn 2000. Radio telemetry, burrow surveys and faecal pellet count data were collected on two areas (Areas 1 and 2) of the farm with different habitat mosaics, to study the potential effects of season and habitat on the spatial distribution of rabbits faeces and thus disease in the environment. Twenty one rabbits were radio tracked and a total of 902 fixes collected. Mean home range sizes (100% minimum convex polygons) were between 2.0 and 7.1 ha per rabbit per season. Home ranges were significantly larger in spring, and in Area 1 which had more moor and woodland and less rough pasture. Rabbits used rough pasture most in Area 1 and gorse scrub in Area 2. In both areas, significantly more burrows were located in gorse scrub than in any other habitat. Most faecal pellets were deposited on the moorland habitat of Area 2 in autumn. In habitats to which grazing livestock had access, the mean rate of faecal deposition was 8571 pellets per ha per day. The greatest risk of disease transmission occurred in habitats of poor grazing quality (e.g., gorse scrub) which were used by rabbits for burrowing and thus contained high concentrations of faeces. The findings of the study are discussed in relation to management practices aimed at reducing disease risk to livestock, including the fencing of scrub and the reduction of rabbit population size to prevent expansion of rabbit burrows from scrub into grazing pastures.     

Influence of grazing management on the production of an irrigated grass/legume pasture in the Rûens area of the Southern cape

Abstract

The production of an irrigated grass/legume pasture was determined using Merino ewes on rotational and continuous grazing systems. The clover content of the pasture declined, while the grass content increased under both systems. The lucerne content of the rotationally‐grazed pastures did not change, but lucerne failed to persist under continuous grazing. Rotational grazing resulted in a lower clover content and, consequently, in a lower production per individual animal at low stocking rates during two seasons, but in a higher pasture production and grazing capacity, than under continuous grazing. At high stocking rates the individual animal production was, however, highest under rotational grazing, resulting in a higher animal production per ha than under continuous grazing.     

The grazing response of cattle to pasture contaminated with rabbit faeces and the implications for the transmission of paratuberculosis

Transmission of Mycobacterium avium subspecies paratuberculosis, the organism responsible for paratuberculosis (or Johne's disease) in ruminants, occurs through the faecal-oral route. As M. a. paratuberculosis has been isolated from rabbit faeces, cattle grazing rabbit faecal contaminated pasture may thus be at risk.A herd of 57 beef cattle was monitored on a farm in Perthshire, throughout the 1999 'grazing year', to investigate whether the cattle avoided rabbit faecal contaminated pasture and thus the potential for disease transmission. Grazing was measured every two days over eight rotations by sward heights on 40 marked treatment plots (0.5 m x 0.5 m) to which 0, 10, 50 and 250 rabbit faecal pellets were added. Cattle were also monitored by an active transponder system which enabled individual animals contacting two plots per field rotation (one control and one contaminated) to be recorded. During the monitored grazing year, grazing pressure was low with a net mean sward offtake of 18% of sward height per rotation. There were no significant differences between rabbit faecal treatments (0, 10, 50 and 250 pellets) with respect to the height or proportion of sward removed, or between the numbers of contacts made by cattle on contaminated and uncontaminated plots. Over 90% of all the cattle contacted contaminated plots, indicating that the potential for disease transmission was widespread among the herd.To our knowledge, this is the first reported instance of a lack of avoidance by grazing cattle towards swards contaminated with faeces, and implies that the potential for transmission of paratuberculosis from rabbit contaminated pasture is high.     

The Development, Clinical Signs and Economic Losses of Gastrointestinal Parasitism in Feeder Cattle on Irrigated and Non-irrigated Dikeland and Upland Pastures

Investigations were carried out over three grazing seasons with parasitized and treated (control) steers on irrigated and non-irrigated upland and dikeland pastures. The stocking rate in each paddock was adjusted by either adding or removing animals so as to maintain as uniform a sward and rate of grazing as possible. Animals were weighed on and off the pastures and fortnightly during the grazing seasons.

During the first grazing season clinically normal steers shedding low numbers of gastrointestinal worm eggs contaminated the parasite-free pastures sufficiently to give rise to large residual pasture infections and clinical parasitic gastroenteritis in grazing stock during the second grazing season. Worm burdens of 100,000 to 200,000 Ostertagia ostertagi and Cooperia oncophora were established in several steers showing marked clinical signs. In spite of treatments with high dosages of thiabendazole in attempts to keep worm burdens at a minimum, there was a slow but gradual buildup of pasture infections in the paddocks grazed by the control steers over the three year period.

During the second and third grazing seasons there were significant differences in the daily rate of gain between the parasitized and control animals on both upland and dikeland pastures. The parasitized groups of steers had daily rates of gain ranging from 0.29 to 0.80 pounds less than their comparable control groups.

Under Maritime conditions, irrigation did not have a consistent effect on weight gains and development of parasitism.

     

A model for predicting livemass gain from stocking rate and annual rainfall

Abstract

The relationship between livemass gain and stocking rate was established for young beef animals grazing kikuyu and Coastcross II pastures in each of five grazing seasons. The annual rainfall within these seasons ranged from 506 mm to 990 mm. Relationships between pasture production variables and annual rainfall are described and these are used to construct a model for predicting livemass gain/ha/season for different stocking rates and levels of annual rainfall.