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 critical importance of planned small ruminant livestock health and production in addressing global challenges surrounding food production and poverty alleviation

ABSTRACT

Small ruminants are particularly well suited to meet United Nations Sustainable Development Goals surrounding food security, human wellbeing and poverty alleviation in different environmental and climatic settings. However the current efficiency of food production from small ruminants in both developed agricultural regions and in lower and middle income countries is woefully inadequate to meet predicted global needs over the forthcoming decades. Most global research to address this challenge is focussed on the genetics of animal growth, conformation and disease tolerance or resistance traits, albeit the practical consequences of such selection and strategies to use genetically improved animals in the field are uncertain. Any long-term benefits derived from small ruminant genetic selection will only be impactful if steps are first taken to keep animals alive, healthy and productive through iterative planned health management. Parasites are the foremost global infectious disease constraints to efficient small ruminant production. Their genetic adaptability to exploit opportunities afforded by effects of climatic or management changes on free-living stages, or exposure of parasitic stages to drugs, presents specific challenges to their sustainable control. Hence, parasite control provides a relevant means of engagement with livestock keepers and farmers on the topic of planned animal health management. The value of parasitology in this regard is enhanced by the availability of simple to use and accessible diagnostic tools.     

Congenital nutritional myodegeneration (white muscle disease) in a red deer (Cervus elaphus) calf

CASE HISTORY A 5-day-old red deer calf was submitted with tachypnoea and dyspnoea, and was reluctant to move.

CLINICAL FINDINGS: Muscular damage was established via elevated creatinine phosphokinase (CPK) activities (5,000 U/L), while concentrations of Se in whole blood were low (24.8 nmol/L). The animal died despite treatment with penicillin-streptomycin and 0.1 mg/kg Se/vitamin E administered by S/C injection.

DIAGNOSIS: Necropsy and histological examination of cardiac and skeletal muscle confirmed the presumptive diagnosis of congenital white muscle disease (WMD). Prophylactic administration of a Se/vitamin E commercial preparation (as above) to another calf born in the same herd one month later was associated with good health and apparently normal growth and development.

CLINICAL RELEVANCE: Congenital WMD due to Se deficiency can be fatal in red deer calves. However, prophylactic administration of Se and vitamin E to neonatal calves may be beneficial for neonatal red deer calves.     

Loss of reserves of Cu in liver when Cu supplements are withdrawn from dairy herds in the Waikato region

Abstract

AIM: To monitor the consequences of withdrawing mineral Cu supplements from two dairy herds with initially high concentrations of Cu in liver.

METHODS: Two herds were selected from dairy farms in the Waikato region of New Zealand that participated in an earlier survey of Cu supplementation practices and Cu status of dairy cows. The herds were fed pasture, grass and maize silage, plus palm kernel expeller (PKE) containing 25–30 mg Cu/kg dry matter (DM) fed at 2–4 kg/cow/day. No mineral Cu supplements were supplied from January 2009. Pasture samples were collected for mineral analysis in September 2008 and April 2009. Concentration of Cu in liver biopsies from the same 9–10 cows per herd was measured on three occasions between April 2009 and May 2010.

RESULTS: Pastures on both farms contained 10 mg Cu/kg DM, 0.1–0.5 mg Mo/kg DM and 3.5–4.0 g S/kg DM. The initial herd mean concentrations of Cu in liver were 1,500 (SD 590) and 1,250 (SD 640) μmol Cu/kg fresh tissue. In the absence of mineral Cu supplements, those mean concentrations decreased over 12 months to 705 (SD 370) and 1,120 (SD 560) μmol Cu/kg fresh tissue, respectively. For cows in the first herd, the rate of depletion of liver Cu reserves was influenced by initial concentration of Cu, such that high concentration led to faster loss according to first-order kinetics.

CONCLUSIONS: Mineral Cu supplementation was not necessary over 12 months for two dairy herds with mean concentrations of Cu in liver >1,250 μmol Cu/kg fresh tissue, grazing pastures containing 10 mg Cu/kg DM and concentrations of Mo <1 mg/kg DM. The quantity and particularly the duration of feeding PKE appeared to be a factor in whether or not the herd lost substantial reserves of Cu in liver during the year. However, the Cu status of both herds in this study was more than adequate to support late pregnancy and mating.

CLINICAL REVELANCE: Copper status of the herd should be monitored and on-farm management of Cu nutrition should take into account all sources contributing to daily intake of Cu. Where Cu supplementation has been excessive and there is risk of chronic Cu toxicity, mineral Cu supplements may be withdrawn for a period commensurate with the expected rate of liver Cu depletion.     

Growth response to increasing doses of microencapsulated vitamin B12 and related changes in tissue vitamin B12 concentrations in cobalt-de cient lambs

AIM: To investigate growth responses of cobalt-deficient lambs to increasing doses of microencapsulated vitamin B₁₂, and to measure associated changes in serum and liver vitamin B₁₂ concentrations over 243 days.

METHODS: From a flock grazing pastures that had low cobalt (Co) levels (about 0.06 mg Co/kg dry matter), 4-6-week-old lambs (n=137) were assigned to four groups and received either no treatment or a subcutaneous injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B₁₂ on Day 1. At approximately monthly intervals, all lambs were weighed and blood samples were collected from a selection (n=10) of monitor animals, up to Day 243. Liver biopsies were also carried out on the monitor lambs (n=8) on Days 1, 124 and 215.

RESULTS: The vitamin B₁₂-treated lambs grew significantly faster (p<0.001) than untreated animals. Liveweights after 243 days were 28, 45, 45 and 47 kg for the untreated, 3.0, 4.5 and 6.0 mg vitamin B₁₂-treated lambs, respectively. Of the initial group of untreated lambs, 68% had to be removed before the end of the trial because of substantial weight loss, but none of the treated animals were similarly afflicted. Serum vitamin B₁₂ concentrations increased in all vitamin B₁₂-treated lambs, reaching a peak at Day 25, and those of the 4.5 and 6.0 mg vitamin B₁₂-treated lambs remained significantly higher (except at Day 124) than the untreated lambs to Day 187. However, at Day 124, but not Day 215, the liver vitamin B₁₂ concentrations of treated lambs were two to three times higher than those of controls.

CONCLUSIONS: The growth rates of Co-deficient lambs were markedly improved by injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B₁₂, and liveweights were maintained for at least 243 days. Serum vitamin B₁₂ concentrations were related to this growth response; concentrations of <220 pmol vitamin B₁₂/l were associated with a 95% probability that lambs were Co-deficient and would thus respond to Co/vitamin B₁₂ supplementation. Based on these data, the current New Zealand reference criteria for Co deficiency should be reviewed.

CLINICAL SIGNIFICANCE: An injection of 3 mg microencapsulated vitamin B₁₂2 given to lambs at tailing will treat Co deficiency and will increase and maintain liveweights in a flock for up to 8 months.     

A practical approach to managing the risks of iodine deficiency in flocks using thyroid-weight:birthweight ratios of lambs

AIM: To establish a protocol for determining the iodine status of a flock and managing the risks of iodine deficiency, using thyroid-weight:birthweight ratios of newborn lambs and serum iodine concentrations of ewes.

METHODS: Data were collected from iodine supplementation studies in Southland and Rangitikei, of sheep fed exclusively pasture or pasture plus brassica during the latter half of gestation (n=350, or 89 per treatment group). The ewes were supplemented pre-mating or at the time of pregnancy scanning with an injection of long-acting iodised oil. Serum iodine concentrations were measured in ewes prepartum in Rangitikei and postpartum at both locations. The thyroid-weight:birthweight ratios (as g/kg) in 229 newborn lambs were determined at post-mortem examination and compared between iodine supplemented vs unsupplemented flocks using probit analysis. Samples of pasture and kale were analysed monthly for determination of iodine and selenium.

RESULTS: Initial mean serum iodine concentration of all ewes was 41 µg iodine/L. Supplementation increased serum iodine concentrations regardless of forage fed, and concentrations remained high for between 127 and 206 days. The range of thyroid-weight:birthweight ratios in lambs from supplemented ewes was 0.09–0.70 (mean 0.35, standard deviation (SD) 0.147) g/kg. Among lambs from unsupplemented ewes, the range was much wider (0.21–8.5; mean 1.61, SD 1.95 g/kg). About half of those ratios were >0.8 g/kg and clearly indicative of goitre, including 62% from the groups on brassica and 18% from the Rangitikei group fed exclusively pasture. Probit calculations showed that a ratio of 0.40 (95% confidence interval (CI)=0.29–0.47) g/kg predicted with 35% probability, and a ratio of 0.80 (95% CI=0.70–0.99) g/kg predicted with 90% probability that a lamb came from an unsupplemented flock.

CONCLUSIONS: Compared to iodine concentrations in forages, thyroid-weight:birthweight ratios more accurately reflected the iodine status of the flock and could be used to identify which flocks to supplement the following year. Serum iodine concentrations of ewes measured before or after lambing did not reflect forage fed, but values near 40 µg/L were associated with goitrous lambs.

CLINICAL RELEVANCE: Thyroid-weight:birthweight ratios >0.8 g/kg were indicative of iodine deficiency, and ewes should be supplemented pre-mating or during pregnancy to prevent goitre the following year. Ratios <0.4 g/kg rarely occurred among deficient flocks, so the probability of benefit from supplementation was low. Intermediate ratios were ambiguous, and the iodine status of the flock could not be determined from biomarkers. In such cases individual-farm supplementation trials might be required to detect and manage the risks of marginal deficiency.     

不同温度下大西洋鳕（Gadus morhua）个体发生早期胚胎生长和卵黄蛋白的利用

本文报道了自受精至孵化,不同培育温度（０－６．１℃）大西洋鳕胚胎生长和卵黄及卵蛋白吸收动态。