Sheep Health, Wellbeing, and Welfare Management

Abstract

Traditionally, sheep are kept in the rural communities for the purpose of milk, wool and meat. Different types of husbandry system exist, intensive, semi-intensive and extensive system of management. Irrespective of the reason for keeping the animal, good management practices should ensure that the welfare of the animal do not suffer. For a profitable performance use of modern available techniques in production is necessary. Estrus synchronization, artificial insemination, early pregnancy detection, embryo transfer and supplemental lamb feeding have all been employed to optimize performance. The welfare of an animal is important. Practices as hoof trimming, shearing, tail docking have been found to improve welfare in sheep production. Diseases of sheep can be categorized into parasitic, bacterial, fungal, rickettsial and viral diseases. Ectoparasites and endoparasites in sheep farming affect the quality of wool and general performance of the animal by causing irritation and poor growth rate due to host dependability. Bacterial diseases in farmed sheep posed a risk of suppurative diseases that affect organs such as the lungs, joints, thyroid gland, lymph nodes and foot which is a consequence of damaging the organs and a risk of systemic diseases which can lead to death of the animal. Good biosecurity measures should be set in place and proper use of vaccines is to be ensued as these tend to keep disease causing agents away from the flock. Sheep farming is a good source of employment hence the need to employ modern techniques to replace traditional practices for optimum performance.

1. Introduction

Sheep belongs to the Kingdom; Animalia, order Atiodactyla, sub-order Ruminatia, family Bovidae, subfamily Caprinea, and genus Ovis. South-western Asia have remained the earliest domestication region and later dispersion into areas of Europe, Africa and Asia. In resent decade domestication has also been done in North and South America, Australia and New Zealand [1]. The survivability of animals and their reproductive capabilities lies on how healthy the animals are reared. Farmers should ensure animals are given close attention to maintain and keep the entire flock and individual animals healthy for better performance [2]. Whenever the overall health of the flock is compromised the entire management process will not be as efficient as possible and these will lead to severe loses in terms of resources [2]. Diseases generally affect performances and only few zoonotic diseases are associated with sheep husbandry. Intensive, semi-intensive and extensive system of management have remained the old systems of management that is still well practiced in sheep husbandry especially in Sub Saharan Africa. Each of the system has its own advantages and its disadvantages based on the selected area and usage [3]. Sheep are generally reared as a source of fiber, meat and sometimes milk which are a general source of livelihood especially to people living in the rural communities. Good management practice is necessary to prevent diseases from entry into the flock. Predisposing factors to diseases can occur during pregnancy, poor feeding, stress and poor management practices. Diseases in sheep can be classified broadly as infectious and noninfectious with various etiologies and management practices.

1.1 Traditional husbandry practices

Traditionally sheep are kept and reared in the house as a sole means of generating income, followed by meat consumption for the households, especially during festivities [4]. From the traditional point of view sheep generally feed on pasture with little or no supplements. Sheep are kept in extensive, semi-intensive and intensive system of rearing [5]. In extensive system of farming sheep are allowed to graze in an open field, they are moved out in the morning for grazing in the open fields and water sources have been river, ponds and streams and left throughout the season. With this method cost of feeding is extremely low however there is danger of the animals coming under attacks by predators. In semi-intensive system of farming both intensive and extensive system are combine together, the flock moves out in the morning for open grazing and later return to their stalls and feed and water is supplemented. The level of nutrition is simply optimal and better in comparison with the extensive system as stall feeding is added which supplements more nutrients. In intensive system of farming the sheep are kept indoors and feed in stalls all through, this is the most expensive of all the systems. However, it has the advantage of proper record keeping and disease management and control. Good disease surveillance can be practiced in this system of farming (Figures 1–3) [5].

Figure 1.

Traditional extensive system of farming.

Figure 2.

Traditional intensive system of farming.

Figure 3.

Traditional semi-intensive system of farming.

2. Tips for profitable farming

Modern systems of farming have brought about ease of welfare management in recent times as more and more discoveries about newer scientific methods of good farming systems are made available. Irrespective of the reason for keeping the animal, good management practices should ensure that the welfare of the animal do not suffer in anyway. Proper planning should however be ensued for good performance. These performance lies on the provision of good environment, type of modern housing, location of the farm site and fencing to avoid the predators. Depending also on the intended reason for the farming (wool, milk and meat), good breeds should be purchased from reputable markets and farms with a good disease free and reproductive performance records. Proper planning should also be ensued for the type of feeding and management practices [6]. Reproductive performance is key to a good and profitable farming and in recent times, the advent of modern technologies such as estrus synchronization, artificial insemination, early detection of pregnancy by the use of ultrasonic pregnancy detectors, have been found to improve performance in terms of reproduction. The proper use of modern vaccines also tends to improve performance by keeping infectious disease agents away from the flock (Figure 4) [7].

Figure 4.

Triad for successful and profitable sheep farming.

2.1 Disease predisposing factors in sheep farming

Predisposing factors are those specific attributes that act either negatively or positively in disease occurrence. These factors can either be from the environment, feeding, type of housing, pregnancy, or from the immune status of the sheep. Factors that causes immunosuppression in animals can directly predispose and animal to disease conditions that can be detrimental. Biobaku and Amid classified predisposing factor in production into four: veterinarian’s factor, animal factor, farmer’s (client) factor and environmental factor. Climate, temperature, humidity, geographic region, wind and vegetation forms the environmental factors. Animal factors include but are not limited to sex, age, specie, genetic makeup and nutritional status [8].

2.2 Welfare management in sheep farming

The welfare of sheep in as good as the production in itself. Limited information is available with regards to extensive management practice in sheep production [9]. There are number of different reasons to why sheep management is important in any given system to ensure high standard of welfare. Maximizing profit in terms of meat and wool is basically the sole aim of a good management practice [10].

3. Practices that improve welfare in sheep farming

3.1 Hoof trimming

As an essential component of sheep management and production hoof trimming plays a vital role in terms of welfare [11]. Across the globe one of the biggest welfare challenges in sheep husbandry is lameness. Sheep are known to show poor indications of impaired movement and posture owing to poor conditions of the hoof [12]. Over grown hooves are prone to cracks and this can predispose to foot rot, a bacterial infectious disease that is caused by Dichelobacter nodosus. It can also predispose to contagious ovine digital dermatitis [12]. The importance of hoof trimming cannot be over emphasized is sheep farming as it poses a great risk to the welfare of the animal.

3.2 Tail docking

Generally, the rationale behind tail docking in sheep farming varies from flock to flock depending on the geographic location, breed, and the type of husbandry system being practiced. There is reduction in the risk of flystrike in tail docked animals because of the prevention of fecal material accumulation around the tail, hind quarters and breech [13]. While other studies showed beneficial application of tail docking others do not especially in sheep with that are less hairy and those that are reared in regions with less incidence of flystrikes [13].

3.3 Shearing

Which is the process of removing or trimming the wool off the sheep is an important aspect of farming. Lack of shearing can predispose animals to risk of parasites and skin diseased [14]. There is also the incidence of sheep having increased body temperatures in summer due to lack of shearing and this have a positive effect on alleviating heat stress [15]. There is also a phenomenon known as “wool blindness” a condition impairing the sight of the animal making the sheep an easy prey. Good eyesight is necessary for survival and plays a vital role in flight away from predators. Survival of lambs is also important in farming, over grown wools tends to cover the teat making in inaccessible to the lamb who will later starve to death [14]. In as much as shearing is important to the survivability of the sheep, care should also be taken when carrying out the process to avoid injury to the skin from the tools as this will predispose to infections one of which is caseous lymphadenitis cause by Corynebacterium pseudotuberculosis.

3.4 Biosecurity

Biosecurity is one of the important components of a good husbandry system. It protects the flock from entry or introduction of new infectious agent. Biosecurity starts at to point of purchasing new animals. The owner of the flock should thoroughly check the physical condition of the animal to be purchased, the previous medical history, any history of travels and the overall breeding history of the farm. A period of 2 weeks or sometimes 30 days is recommended for newly animals to be kept under quarantine. Quarantine area should not be situated close to the main flock; 100 feet is recommended [16]. The area should be isolated under confinement preferably a new building should be provided for this purpose at least to prevent the entire flock from coming close or having a direct contact with the new animals. Quarantined animal’ s hooves should be trimmed and duly checked for foot rot. The animals should be made to stand in a footbath containing zinc sulfate [16]. Newly purchased animals should be dewormed thoroughly to prevent introduction of drug resistant worms into the flock. During housing construction provisions should be made for foot dips and full body dips for sheep as this will not only prevent against incoming diseases but also will serve as points for medicaments in ectoparasite treatment. Routine disinfection of pens, vehicles and equipment is also recommended in a good husbandry.

3.5 Methodology

Published literature about the different types of sheep farming from the traditional point of view were accessed from the internet and in-depth analysis and review of materials was carried in accordance to scientific standard in order to draw this manuscript. Farms were visited within Maiduguri metropolis to further categorize the type of practiced husbandry and images were snapped using a digital camera. Charts were drawn using Microsoft word chart tool.

3.6 Vaccination

Vaccination plays a vital role in sheep farming because they are cheaper in comparison to the cost of treatments. Different vaccines are available for sheep and goats which protect against different disease causing agents such as bacteria and viruses. Those vaccines must be easily accessible to the farmer and also economically affordable. Clostridial vaccines are the most widely used in North America because of the deadly nature and economical importance of the diseases cause by the organism [17]. Clostridium tetani an etiological agent of tetanus is known to pose a great risk especially after castration, tail docking and shearing to unvaccinated flock. Aside clostridial vaccines several others also exist which protect against infections and ailments. These include both not limited to vaccines that protect against contagious ecthyma, caseuos lymphadenitis, footrot, abortion, epididymitis, ovine pneumonia, and rabies. Traditionally when interacting with farmers they will tell you they have not used vaccine before with the claims that they have not suffer loses (this probably cannot be true). Each sheep farmer should however weigh the advantages and disadvantages of using vaccines against specific disease. The cost of the vaccine should not exceed the expected loses. The best management practice is that the expected loses should always exceed the expected loses. The farmer should not wait until there is an outbreak before he will vaccinate, he should always be guided by the risk and stress involved during outbreak. It is always better to prevent and also cheaper than to cure [16].

4. Common parasitic diseases of sheep

4.1 Endoparasitism

Helminthosis is an important clinical disease caused by internal parasites (helminths). This disease conditions occur in both animals reared on free range and those of pasture. Lungworms, flukes, nematodes and cestodes can all cause harmful effect to the flock. The eggs of the parasites are present on the pasture especially during the early rainy seasons when grasses are sprouting and are ingested by the animals and develop into adults in the animal at their predilection sites. The adults later lay eggs and the eggs are shed in feces and the cycle continues. It is always important to design a good parasite control in sheep farming. Sheep that are reared on free range tend to harbor more parasites than those reared on pasture. Rough hair coat, listlessness, anemia, diarrhea. Stunted growth are the general signs of helminthosis [18]. Helminths tend to be more in the middle of the rainy season, and also in flocks that are densely populated. Different antihelmintics of veterinary importance exist, however, care should be taken to prevent over usage and possibility of building drug resistance worms especially with haemonchosis (Haemonchus contortus) and Trichostrogylosis (Trichostrongylus colubriformis) infestation in the United States [19]. Haemonchus is among the most pathogenic helminth of sheep and goats causing mortality and morbidity in flocks devoid of routine deworming (Table 1) [20].

Parasite	Common name
1. Haemonchus spp	Barber’s pole worm
2. Trichostrongylus axei	Small stomach worm
3. Trichostrongylus spp	Bankrupt worms
4. Strongyloides papillosus	Intestinal threadworm
5. Nematodirus spp	Thread-necked intestinal worms
6. Thysanosoma actinioides	Fringed tapeworm
7. Oesophagostomum columbianum	Nodular worm
8. Chabertia ovina	Large-mouth bowel worm
9. Trichuris spp	Whipworms

Table 1.

Parasites of small ruminants and their common names.

4.2 Ectoparasitism

Ectoparasites are of great welfare concern in farmed ruminant because of their effects on the general wellbeing. They do not cause serious mortalities per se unless if there is heavy infestation. In production if ectoparasites are not controlled infestation might lead to unthriftiness, poor weight gains and loss. Animals on low nutritional supply, poor health status and young animals tend to be more susceptible to the condition. Broadly ectoparasites belong to one of the following; ticks, mites, fleas, mites and nasal bots (Oestrus ovis). Generally, ectoparasites cause anemia and severe irritation to the animal while others serve as vectors of protozoal, virus, rickettsial, and bacterial disease agents [21]. It also affects the wool and hide quality occurring as a result of constant scratching due to severe pruritus. If left unchecked wounds created by these parasites can serve as a nidus of entry for secondary bacterial contaminants leading to systemic infection and mortalities. Control usually is by dipping regularly with acaricides which will take care of ticks, lice, fleas and mites during one dipping, these have been reported to increase the general performance in terms of wellbeing and welfare [7]. Care should however be taken if there are external wounds as this will cause toxicities that will be fatal. Owners of the flock and care givers should occasionally and at regular intervals send fecal samples for worm load count.

5. Suppurative diseases of sheep

Sheep are susceptible to many bacteria causing suppurative diseases. These diseases affect various systems in the body leading to mortalities in many instances if left untreated. Some diseases are however under reported due to improper diagnosis or lack of available diagnostic laboratories around. Suppurative disease of sheep caused by different pyogenic bacteria has been reported to affect different organs of the body such as thyroid, central nervous system, joints, lungs, lymph nodes and muscles [22, 23, 24]. Those suppurative infection can pose the risk of severe systemic infections, calcification of the organs and organ failure if left unchecked [23]. There has also been report on general emaciation associated with organ damage due to suppurative disease caused by bacteria [22]. Bacteria such as Staphylococcus, Streptococcus, Escherichia coli, Corynebacterium pseudotuberculosis, Klebsiella, Actinomyces and Pasteurella have been incriminated as the etiological agents of suppurative diseases in sheep farming [25]. Sheep are farm animals raised for the purpose of meat production in some respect and any suppurative condition affecting the organs will lead to condemnation of the organ and possibly whole carcass during meat inspection. When the bacterial diseases are associated with the mammary gland it is also of public health concern as milk from sheep is also widely consumed by humans.

6. Diseases of zoonotic importance is sheep farming

Diseases can be transmitted from sheep to man and vice versa. These phenomenon is termed as zoonosis and is of public health significance. Increasing demand of milk from sheep and other animals has become popular in recent times. Most zoonotic diseases of small animals are transmitted by contact, inhalation and in some instances by vectors. Population at risk are famers and animal handlers such as veterinarians. However, consumption of raw or uncooked products have also been incriminated with milk serving as one [26] Camphylobacter spp, Brucella miltensis, Staphylococcus aureus, Listeria spp, E. coli (Shiga-toxin producing) and Salmonella spp have all being incriminated when sheep milk is consumed by human [27].

7. Conclusion

Sheep farming can be said to be a good source of employment especially to people in the rural areas. Modern management practices however help improve welfare in a good husbandry. Preventive methods of disease management have been the best approach in health care as this tends to be cheaper and cost effective than the curative processes which poses stress not only to the animal but also to the farmer. Knowledge about the diseases of sheep is important to the farmer in terms of planning and good welfare assessment.

Acknowledgments

The author appreciates the Department of Veterinary Pathology, Faculty of Veterinary Medicine, University of Maiduguri, Nigeria for providing opportunities for research and self-development.

Conflict of interest

The author has no conflict of interest to declare.