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Reviewing the ‘survivability’ of goats

by
01 February 2014, at 12:00am

Veterinary Practice reports on some of the papers presented at the latest meeting of the Goat Veterinary Society

THE Goat Veterinary Society (GVS) has a reputation for involving students and new graduates and Rachel Simmons, a final-year student at Edinburgh, presented the results of a survey on survivability and longevity in commercial goat herds, during its latest meeting.

There is a lack of data about milking goats and four herds with an average of 1,800 milking does made their data available. The data were taken at face value and differed in detail between herds but do provide an indication with which other records can be compared.

The two most common causes of kid mortality found were pneumonia and diarrhoea with peak losses between March and July. The mean culling age within the adults was 4.5 years but there were a significant number of older goats. Older goats were culled most commonly for gangrenous mastitis, mastitis and Johne’s disease.

Gangrenous mastitis also accounted for over half of the culls in the 1-2 year old group. Most Johne’s cases were recorded for the 2-4 year old group but there were few laboratory confirmations or post mortem evidence.

Fertility and lameness were not recorded as significant reasons for culling but this aspect needs to be looked at more carefully. This study is a useful starting point and members are seeking further information on which to establish baseline figures that will be of particular value in herd health planning.

Kit Cornell, a fourth-year student at Bristol, described the findings from a questionnaire on the occurrence of endo- and ectoparasites and the treatments applied. Faecal samples were received from 13 respondents during February 2013. These samples came from a selection of goat herds including hobby farmers and milking units.

Unsurprisingly, the common endoparasites were worms and coccidia but there were significant worm egg counts in the samples. This was not expected in February. Post-hatching larvae were Teladorsagia, Trichostrongylus and Haemonchus in roughly equal populations. Haemonchus is not frequently encountered in goats.

Benzimidazole or ivermectin were commonly used to worm goats with 73% of the goat keepers considering that their choice of anthelmintics and its use was effective. Choroptic mange was the most common ectoparasite with a variety of treatments used from within large and small animal products. There are no ectoparasiticide products with a marketing authorisation for goats. This project has added to the general awareness of the lack of recorded information and efficacy data with parasites and goats.

Nick Perkins has been involved with goats in practice for many moons and in his current role with the Veterinary Defence Society he considered the issues with prescribing for goats.

With few products available that have a marketing authorisation, veterinary surgeons have to apply the cascade principle with inherent pitfalls. Off licence use may be associated with higher risk and this needs to be explained to the owner. Off licence consent forms should be considered by practices, he said, particularly if a product is regularly used as part of a health plan.

Contraindications need to be carefully considered when choosing a medicine and the accurate weight of goats is an issue because “they are heavier than they look”. Withdrawal periods with milking animals are a practical consideration with the increasing production of commercial milk products.

Murray Corke from the University of Cambridge presented an overview of some work he is currently involved in collaboration with seven other European partners, and funded by the EU. The project is entitled “AWIN” (animal welfare indicators).

The routine use of analgesics in animals is only a fairly recent development – mainly within the last 20 years. Farm animals tend to hide any signs of pain since they have effectively evolved as prey animals and become vulnerable if they appear weak or ill. Experienced stockmen can often recognise early signs of illness and pain, but they often cannot explain why.

Using sheep as their model, the Cambridge team have been looking at identifying pain biomarkers associated with footrot and acute mastitis. Trials involved clinical examination, laboratory examination of samples including blood, wool and faeces for cytokines and other metabolites in two groups, one of which used NSAIDs alongside other conventional therapies.

Supporting these approaches was a study of facial expression, particularly ear carriage, partial closing of lids and changes to cheek musculature, which varied depending on severity of discomfort. All these measurements then contributed to an overall composite pain score. Further information is available at www.animal- welfare-indicators.net/site/.

Overseas projects

The GVS supports some overseas projects and Rob Ankcorn described the work of two local projects and the charity “Send a Cow” in Rwanda, which also sends goats, rabbits and bees.

Following the genocide in the country the soil has become impoverished and local people are being taught the value of compost and manure and growing vegetables in raised beds. As well as supplying livestock, support is provided to ensure that the animals remain fit, healthy and productive. The improvements achieved enable locals to become self-sufficient.

Copper deficiency

Richard Laven from Massey University in New Zealand described copper deficiency as one of the most commonly diagnosed mineral deficiencies in ruminants. VIDA data between 2005 and 2012 confirmed 44 cases of deficiency (but only one of toxicity) in goats, compared to 497 deficiency and 387 toxicity in sheep, raising the question as to whether goats are less susceptible to toxicity.

Diagnosis, however, is not simple, and no single test can give a definitive answer. Signs of deficiency in goats have included depigmentation, defective keratinisation, enzootic ataxia/swayback and reduced weight gain.

Primary deficiency can occur if there is simply too little copper in the diet, but secondary deficiency occurs as a result of reduced absorption from the gut due to antagonists such as molybdenum, sulphur and iron.

The speaker emphasised the importance of assessing liver copper levels either from cull livers, or from biopsy samples. Liver copper levels demonstrate the actual store of available copper, which single blood samples cannot; these can be maintained within the reference range even as liver copper levels fall dramatically.

The measurement of TCA insoluble copper can give an indication of “bound” copper if secondary copper deficiency is suspected. Measurement of the copper dependent enzyme caeruloplasmin offers an alternative enzymatic method, but as it is also an acute phase protein, false elevation can occur following inflammatory insults.

Supplementation if required can be given either orally or by injection. Injectable copper products give a rapid response, but the speaker did favour copper in slow-release bullet format, being cheaper, safer and longer lasting.

History

Gathering research for a talk to the Veterinary History Society, David Harwood highlighted that the goat was the first livestock species to be domesticated, with archaeological records dating back 10,000 years.

Evolving from the wild goat or Bezoar ibex, the benefits of goats to mankind include milk, meat, skins to carry water and wine, faeces for fuel, pulling carts – and kid skin was an early writing paper. Greek mythology and Egyptian hieroglyphs depict the goat and the animal features in satanic rituals and masonic folklore.

Unrelated, perhaps, David recommended delegates to consider the Animal Welfare Foundation as a worthwhile charity with ongoing projects aiming to improve the welfare of all animals through veterinary science, education and debate. n Many thanks to David for providing technical notes and photographs from the York meeting.