The three roles which veterinarians in rural practice commonly have on sheep farms are:

To be effective in these three roles, veterinarians need to know how sheep farms work and how farm decision-making occurs. This requires a sound working knowledge of the sheep reproductive cycle, seasonality, pasture growth, farm calendars and flock structures. Farm decisions are ultimately driven by a need to maintain a profitable and robust business. They are made to offer the greatest 'sustainable' return to the producer, within a framework of limitations imposed by personal objectives or external regulation. Examples of personal objectives are the desire to have a low risk of business failure or to avoid employing any or additional staff, and examples of limiting regulations are the prohibition of the use of certain agricultural/veterinary chemicals or restriction on the land use of some areas of the farm.

Farm decisions are not made to maximize condition score, animal health, wool production per head or the lamb marking percentage, but to make profits from the farm as a whole. This important principle will be developed in Chapters 2 and 3 in discussing farm economics and farm systems. Veterinarians must understand that a desire for business success drives farm decision-making. If veterinary advice does not increase farm profitability and financial security for the client, the veterinarian will probably not retain the client for long.

There are other, less common but important roles which veterinarians may have on sheep farms. These generally fall under the heading of consultancies. Effective veterinary sheep consultants or specialists must be able to carry out all of the above roles and give sound advice about stocking rate, genotype selection, flock structure, pasture production, wool clip preparation, marketing and financial management. A full training in these latter fields is beyond the scope of this undergraduate course; various forms of postgraduate training are necessary for graduates who choose to develop their careers in this direction. Nevertheless, the generalist rural veterinarian does require a nodding acquaintance of these topics in order to develop sound recommendations and plans.

Veterinary education and the veterinary role on sheep farms

The value of individual sheep in commercial flocks is generally too low for diseases with a low incidence to attract veterinary intervention. Rams, particularly newly purchased ones or highly valued ones, are a general exception. They often have replacement values 20 to 30 times that of ewes or wethers, even in commercial flocks. Flocks of sheep at risk of disease, however, may consist of 100 to 1000 or more individuals. The practice of sheep veterinary medicine is often concerned with the diagnosis of disease in a portion of the flock, perhaps the first few cases of a potential epidemic, and the institution of preventive plans for the rest of the flock. The large number of animals at risk and the large productive value of the flock justify significant expense on veterinary investigation and provides the veterinary practitioner with ample financial scope to display his or her diagnostic skills.

One would have to say that Australian sheep flocks are still under-serviced by private veterinary practitioners. The reasons for this are numerous. One major factor has been the emphasis on individual animal medicine in veterinary education and in most facets of veterinary practice work. Sheep growers have perceived this, usually correctly, and used their veterinary practitioner for services to individual animals of value - rams and farm animals of other species such as sheep dogs and house cows. Occasionally, animals are presented at clinics for post-mortem but the determination of action required on the farm in the light of the diagnosis has been very much in the hands of the client rather than the veterinarian.

Several aspects of veterinary education have led to this. First, a failure to appreciate that diseases in sheep flocks require an epidemiological approach to their investigation and management. Second, a difficulty in considering the economic consequences of both the disease and the steps that are necessary to reduce the disease prevalence, and that at some level of incidence the latter may cost more than the former. Third, a misunderstanding of the consequences of changing one aspect of a farm system for other parts of the farm system. A typical example is a veterinary tendency to recommend lowered stocking rates to reduce the incidence of nutritionally related diseases. The fact that there may be other less obvious and more complex strategies which achieve similar improvements in the disease condition without the economic consequences of reducing sheep numbers, is seen by veterinarians as 'the farmer's business' and beyond his or her brief as a farm advisor.

In the last twenty years, sheep veterinary education in Australia has started to address the need to change the approach of graduating veterinarians. Unfortunately, a strong influence on such graduates is the expectations and actions they experience in the practices which employ them after leaving the universities. Few new graduates will have the ability and confidence to offer novel services to clients who are not expecting such services when the more experienced practitioners they work with do not practise the 'new' approach.

These notes aim to encourage an interest in the practice of sheep veterinary medicine which is compatible with sound sheep management systems. The veterinarian must remain a sheep health expert but his/her knowledge of sheep management and sheep production systems and strategies must be developed to a moderate degree. This presents difficulties for many, particularly those which have not been exposed to rural life significantly before graduation. The problem however, is far from insurmountable and the rewards are large. Sheep producers react quickly to the presence in their community of a veterinarian who, in their words, 'knows what sheep farming is all about!'. They seek opinions on a wide range of sheep health matters and, if the advice is considered practicable, will implement the recommendations. This offers tremendous satisfaction to the veterinarian who will be able to witness the confirmation of the diagnosis and judge the effectiveness of the recommendations in the improvement of profits for the client.

First, however, the veterinarian must develop knowledge of sheep grazing systems both in general and specifically for the district and the client' s property. A primary rule for sheep veterinarians emerges - attend the farm. Much becomes obvious when sheep and their environment are viewed first hand provided, of course, that the veterinarian knows what to look at, to look for and to ask. While high levels of skill only come with experience, the following suggestions might help develop a basic approach.

Description of a sheep farm

Breed and genotype [1]

The various types and breeds of sheep present in Australia are well described elsewhere (see Recommended Reading). In short, Merinos dominate the national sheep flock, making up about 90%. Merinos are considered a wool-producing breed with limited suitability as a meat sheep, although there has been recent interest in exploiting the meat characteristics of the strong wool South Australian Merino, particularly in light of the consistently low prices paid for broad wool at wool sales. Approximately 7% of the national flock is Border-Leicester Merino crossbred ewes, which are the preferred type used as prime lamb dams. Sheep of other breeds are not numerous but some of these breeds are very important as prime lamb sires, particularly Poll Dorsets, Suffolks and Texels. There are some pure-breeds considered dual-purpose (meat and wool) and the Corriedale is the most populous of these in Australia. A discussion about the breed characteristics and the factors which make some breeds and genotypes more suitable for particular environments is beyond the scope of this text, but is essential knowledge for veterinarians working with sheep.

Production objective

Production objectives vary between farms within districts and between districts but, in commercial Merino flocks [2], the chief objective is to maximize income from the sale of wool. Nevertheless, additional income is derived from the sale of surplus sheep. Some Merino properties join a portion of the ewe flock to Border Leicester rams, so then income from wool is supplemented by the sale of prime or unfinished crossbred lambs and crossbred ewe lambs or hoggets. On prime‑lamb properties the chief objective is to maximize income from the sale of prime lambs, however significant income is derived from the sale of crossbred wool and cast-for-age (CFA) ewes. In stud flocks and other ram-breeding flocks, the production objectives different in emphasis from commercial flocks.

Flock structure and stocking rate

Flock structure and stocking rate will be examined in later chapters. It remains now in this introduction to consider the management calendar.

Farm management calendars

The timing of major sheep husbandry and management events on farms (the farm management calendar) is important information to veterinarians for three reasons. First, the timing of events may be an important predisposing factor to outbreaks of disease. The clearest examples of this are the relationship between the time of lambing and the incidence of pregnancy toxaemia in ewes; and the incidence of nutrition related disease in recently weaned lambs. Second, preventive medicine strategies, like drenching, vaccinating or footrot control, should be integrated with other management events which require mustering, to save time and labour for the farm operator. Third, the timing of particular management strategies can have implications for total farm productivity unrelated to occurrences of disease. This latter area is generally not considered the role of the general practitioner but forms a significant part of the activities of sheep specialist veterinarians.

Management calendars depend on whether the farm is a non‑breeding or breeding enterprise. The optimisation of the management calendar for a particular farm depends on the production objective and is complex, being influenced by environmental, disease and economic considerations. On non‑breeding farms, the key decision is when to shear. On breeding properties the key decision is when to join, followed by when to shear. The timing of most other husbandry practices will be related to these key decisions.

Non-breeding flocks

On non‑breeding properties, the sheep husbandry practices include some or all of the following:

A sample calendar for a farm in western NSW running strong‑wool (.24μ) Merino wethers only is shown in Table 1.1.

Table 1.1 : Hypothetical management calendar for a non-breeding flock

Practice	Time	Comments
Shearing	May - September	Why not in the warmer months?
Dipping	2 to 3 weeks after shearing	Or ' pour-on' immediately off-shears. Are lice present and is dipping necessary?
Crutching	September - April, depending on when shearing occurs	How much crutching do wethers require? What is the duration of the blowfly season?
Jetting	September - May	If fly strike is occurring or likely to occur
Drenching	December and February	Tactical treatments at other times
Pizzle rot prevention	September	Only necessary on improved pastures

Breeding flocks

On breeding properties there are additional husbandry practices which relate to the reproductive cycle and the management of pregnant and lactating ewes, lambs and weaners. These include some or all of the following:

A sample calendar for a Merino farm in southern NSW with winter rainfall and an autumn lambing is shown in Table 1.2. An example for a Merino flock in northern NSW is shown in Table 1.3. These calendars are, of course, incomplete. Not considered are such topics as:

Table 1.2 : Hypothetical management calendar for an autumn lambing Merino flock in southern NSW (winter rainfall zone)

Practice	Time	Comments
Joining	Dec - January	For 6 weeks from 1 Dec
Crutching	Early February	Shear rams
Vaccinate all ewes	April	Pre-lambing booster
Lambing	May - June	Lamb over 7 weeks
Mark, mules and vaccinate lambs	Late June	Lambs 1 to 8 weeks old
Wean lambs	Early September	At 3 to 4 months of age
Shearing	September	All sheep including rams
Class ewe hoggets	September	Before or at shearing
Purchase rams	September	Ready to join in December
Dip all sheep	September	2 weeks off-shears
Sell cull maidens, CFA ewes, CFA rams	October
Isolate rams from ewes	October	6 to 8 weeks before joining
Sell wether weaners	November	These weaners may be retained

Table 1.3 : Hypothetical management calendar for a spring lambing Merino flock in northern NSW (summer rainfall zone)

Practice	Time	Comments
Joining	March - April	For 6 weeks from 1 March (inside the breeding season)
Shearing	June	All sheep including rams
Dip all sheep	July	2 weeks off-shears
Lambing	August - September	Lamb over 5-6 weeks
Mark, mules and vaccinate lambs	Late September	Lambs 1 to 7 weeks old
Wean lambs	Early December	At 3 to 4 months of age
Purchase rams	December	To use in March
Crutching	January	Shear rams
Class maidens	January
Sell cull maidens, CFA ewes, CFA rams

The calendars in Tables 1.1 - 1.3, although fairly typical, would be optimal on only a small proportion of Merino properties. As before, optimal is here defined in terms of farm profitability and security for the client. Procedures for the optimisation of individual calendars will be examined in subsequent chapters. This requires further examination of topics such as stocking rate, seasonality in pasture quantity and quality, reproductive performance and markets for lambs, weaners and other surplus sheep.

Although not discussed here, a calendar for an irrigation farm which produces prime lambs from crossbred ewes would show marked differences from those illustrated. The availability of irrigation gives the producer more control over seasonal pasture quantity and quality, and hence more freedom to vary the time of joining and marketing.

Sheep Health & Production

Chapter 1 The sheep farm revisited

The role of the veterinarian in the Australian sheep industry