Sheep Health, Husbandry and Disease

A Photographic Guide

Agnes C Winter, Clare Phythian

• Éditeur: Crowood
• Année: 2013
• ISBN:
  9781847975409
• Sujet: Technology & Engineering
• Sous-sujet: Animal Husbandry

This comprehensive book covers all aspects of sheep health and disease, and sheep husbandry throughout the annual breeding cycle. Through extensive and detailed photographs it highlights the disease and welfare issues that can arise within the great variety of breeds and flock types. Written by two veterinary surgeons closely involved in sheep health, this book takes a veterinary view of husbandry and emphasizes the importance of keeping diseases out of a flock. From practical tasks such as how to check teeth, feet and udders, through to vaccination schedules, injection techniques and parasite control, it covers the whole life cycle of your flock. Topics covered include: Routine procedures; Selecting breeding stock; Internal and external parasites; Tupping time; Pregnancy; Lambing ewes; Lameness. An essential guide to all aspects of sheep health, disease and sheep husbandry through the annual breeding cycle. Invaluable reference for anyone who keeps sheep on a small scale, with one or two as pets, to those with a commercial flock. It will be of interest also to agricultural and veterinary students and shepherds working with valuable pedigree flocks. Considers how to tackle common diseases, the potential problems that can arise and the preventative measures that can be taken. Superbly illustrated with 609 extensive and detailed colour photographs. Agnes Winter is a specialist sheep vet and Honarary Professor of the Veterinary School at the University of Liverpool and Clare Phythian is a full-time veterinary surgeon specializing in sheep health and welfare.

1 Keeping Your Flock Secure

To some people the title of this first chapter might suggest that it is just concerned with fencing, keeping your sheep in and other people’s out. Of course this is an important part of managing flocks that are kept on enclosed land, but flock security has a much wider meaning, encompassing all the precautions that should be taken to minimize the introduction of costly infectious diseases.

Types of Flock

Flocks can be simplistically classified according to how they are managed, together with the associated disease risks.

Closed purebred flocks: Closed flocks breed their own replacements and have no contact with sheep in other flocks. In most of these flocks there will be the occasional purchase of new rams, and these are the risky animals as far as possible disease introduction is concerned.

Lowland flocks of crossbred ewes: These include Mules, Welsh or Scotch halfbreds, and Greyfaces or other recognized crosses. Unless a hill flock to breed these is in the same ownership, young replacement ewes are likely to be purchased every year, meaning annual opportunities for disease introduction. Terminal sire breed rams (such as Texel, Suffolk and Charollais) are also likely to be purchased annually.

Purebred isolated hill flocks: These graze extensively, but are prevented from mixing with other flocks by fencing or natural geographic features. These flocks may also make occasional purchases of rams, which pose a potential risk.

Hill flocks that graze extensively on land with access by several flocks: These are at risk of picking up disease from each other, and unless there is cooperation from all flock owners involved, it can be extremely difficult to control infectious disease, particularly sheep scab.

Store lamb finishing flocks: In such flocks weaned lambs may be purchased from many sources and mixed together, creating the perfect opportunity for disease spread.

Fig. 2 Closed purebred flocks should be able to achieve high health status, but beware of the risks in bringing in new rams.

Fig. 3 Double fencing makes sure that a closed flock cannot contact neighbouring animals, and keeps stray sheep out.

Fig. 4 Mule ewes with their lambs. This type of ewe is bought in from flocks that breed them by crossing hill ewes with Bluefaced Leicester rams.

Fig. 5 A hill flock grazing on fenced land, but do the sheep have contact with others on the mountain beyond?

Fig. 6 Where flocks belonging to several owners graze extensively on common land, disease risks are high and it needs cooperation from all involved to control them.

Fig. 7 Markets, where sheep from many different flocks come into contact, form a potential source for disease spread, which is why there are restrictions on movements for several days after purchase.

Fig. 8 Showing sheep often allows contact with animals from other flocks so poses potential health risks.

Fig. 9 Sheep scab is one of the most important diseases that can be introduced into a flock via bought-in or stray sheep.

Fig. 10 This ram has a barely noticeable healed scar below the ear indicating it has almost certainly had an abscess as a result of CLA infection. He is likely to have other abscesses elsewhere in his body so could introduce the disease into a previously uninfected flock.

Draft ewe flocks: Draft ewes originate from a variety of sources; they are often purchased through markets, and are probably the most risky of all sheep to introduce into a flock.

Organic flocks: These flocks are run according to organic farming principles, with strict regulations regarding fertilizer and pesticide use. Conventional medicines can be used to treat sick individual animals, but vaccine use is usually based on a known risk of disease on the farm involved.

Milking flocks: Compared with countries such as Spain and Greece, milking flocks make up a very small part of the UK sheep industry. Most milk is made into products such as cheese.

Of course there are many more types of flock than those described above, but the examples serve to show that the more mixing of sheep that occurs, the greater the risk of introducing diseases that can have a serious impact on the welfare and profitability of the flock. There are other opportunities for disease spread, for example:

• showing sheep
• borrowing rams for small hobby flocks
• acquiring spare lambs from another flock for ewes that have lost their own lambs
• straying sheep are put with a nearby group of sheep through an unlocked gate by well meaning passersby.

Two real examples will serve to highlight the possible consequences. In one flock of 500 ewes, two new rams were purchased...