**3. Sustainable livestock production and the challenge of animal pests and diseases**

With development efforts in the livestock sector, world animal production has continued growing with increased productivity. Between 1995 and 2002, the world total meat production increased by 19%, the total milk production by 11%, and the egg production by 23% [9]. Notwithstanding the research support for the development and improved productivity of the livestock sector, the sustainability of livestock production is still being challenged by several production and environmental factors; with the degree of impact being influenced by the management system put in place by farmers. While farmers may try as much as possible to give their animals all the necessary care in terms of good housing units—spacious, dry and well ventilated, quality feeds and water, and necessary healthcare, it remains inevitable to completely prevent the incidence of pests and diseases in livestock management basically because of the impossibility of eradicating disease-causing pathogens which could survive in almost all avenue. Reduction of the incidence of pests and diseases in farm animal management has though been achieved by a combination of good hygiene, appropriate use of vaccines and medical therapy, and selection of disease-free breeds of livestock, the result is by no means an eradication of infectious and contagious diseases owing to the fact that a multiplicity of pathogenic agents are inducing emergence of complex diseases that may even be difficult to diagnose [16].

Pathogens, which are groups of organisms that cause diseases in farm animals, exist in form of viruses, bacteria, fungi, protozoa, and parasites, and are so small that they cannot be ordinarily seen by sight except with the aid of electronic magnifiers. These pathogenic micro-organisms or microbes exist in different sizes and shapes and are readily transmitted to animals through various substrates or vectors such as water, soil, waste or faecal matter, humans and animals [17–19]. Viruses are very small micro-organisms and much smaller than all other pathogenic organisms such that it can only be viewed with a strong electronic microscope [16]. However, the micro-organisms can only survive and/or multiply within living cells basically because it lacks cell membranes, cytoplasm, ribosomes, and other cell organelles [20, 21]. This mode of survival and multiplication by viruses make it possible to destroy the cells of the infected host thereby result in certain diseases. About 60% of animal diseases are caused by a virus and unfortunately, such viral diseases have no cure thereby resulting in the death of infected animals [17]. On this note, preventive actions, usually by vaccination, are required to ensure the healthiness of farm animals. Viral diseases of farm animals include foot and mouth disease, rinderpest, bluetongue, vesicular stomatitis, swine fever, fowl pox, avian influencer, etc.

Bacteria, on the other hand, are relatively larger than viruses and also take different shapes and sizes but most are visible under an ordinary microscope. The micro-organisms, unlike viruses, could survive anywhere—within and outside living cells but could sporulate to form a protective coat that makes them survive in any environment for a long period, even years, and later cause infectious disease(s) in farm animals [16]. Bacteria that survive outside living cells could remain inactive until the emergence of favourable conditions to gain entry into the body of the animals, either through the skin or the eyes, breath into the lungs, consumed through food and water, to cause infections [22]. Similarly, some bacteria within the living cells, such as *Bacillus* and *Clostridium* species, envelope themselves with protective spores or endospores, which become dehydrated and highly resistant to an environmental condition such as heath, cold, or chemical compounds. The endospores, within which the bacteria may remain inactive for many years, produce

**29**

*Farm Animals' Health Behaviours: An Essential Communicative Signal for Farmers' Veterinary…*

endotoxin—a deadly substance that causes disease in animals [23, 23]. Bacterial diseases of farm animals include botulism, paratyphoid, anthrax, brucellosis, foot rot, tetanus, etc. Bacterial diseases are however not as deadly as viruses as these could be readily treated with antibiotics, particularly when detected on time. Besides, not all bacteria cause disease as some are of great value in ruminant digestion where they

In similarity to bacteria, fungi are widespread, exist in various shapes and sizes, and could survive in nearly all forms of environment, be it water, soil, air or in the mould on stale food and mushroom for a long period that runs into years. The micro-organisms are though ordinarily harmless, they cause disease in some situations which can be damaging or even devastating in some cases [17, 25, 26]. Some fungal diseases affect the mucous membrane (mucosal) though, most of them affecting the skin (cutaneous) by colonising and destroying their tissues [27]. Skin diseases are though rarely critical or deadly, their resultant irritation discomfort the animals leading to inhibition or disruption of their feed intake and consequently, a drastic drop in productivity [28]. Diseases of fungi could be highly contagious and primarily spread by direct contact between animals; with the clinically infected animals as the greatest source of infections [26]. Examples of fungal diseases include ringworm, aspergillosis, candidosis, mycotic, protothecosis,

Protozoa are single-cell microbes that survive both inside and outside living cells and could be found in most habitats. Most of the protozoa are though harmless and even play a vital role in controlling bacteria population and biomass; some are however parasitic pathogens of humans and animals [29] and as such significantly cause diseases in farm animals and even as potential drivers of zoonotic transmission [30, 31]. The parasites are a significant cause of abortion and infertility in domestic ruminants [32] and a relatively uncommon group of respiratory ailment [33]. Epidemiological situations of protozoan infection may occur as a single infection or zoonoses and may be sporadic in otherwise healthy hosts [34]. Also, infection of the nervous system is mostly fatal. An epidemiological situation that corresponds to pseudoepidemics occurs in a large host of the animal population due to a common source or poor housing conditions of the animals characterised by poor-quality or badly-stored bedding. Protozoan parasites in poultry are coccidia (species of the *Eimeria* genus), cryptosporidia (*Cryptosporidium baileyi*), and

Alongside the pathogenic micro-organisms causing diseases in farm animals are parasites that depend on the animals for growth and/or survival [34, 35]. The parasites may live and survive inside or outside the body of farm animals as internal and external parasites. Common parasites of farm animals exist as worms, flukes, protozoa, and insects such as lice, mites, ticks, flies. Unlike the parasitic protozoa, most parasites are visible to sight but some mites and worms can only be seen under a microscope at their early stages [16, 34]. With the dependence of the parasites on host animal(s) for survival, they may either inhibit the normal physiological functioning of the animals or act as a vector of other diseases thereby resulting in negative impacts on the health and welfare of animals. Such negative impacts, particularly by the internal parasites, may be manifested as anaemia as a result of substantial blood loss, reduction of the animals' appetite resulting in debilitating health and susceptibility of the animals to other diseases, diarrhoea and death of the animals arising from severity of the parasitic impacts [34, 36, 37]. The external parasites, on the other hand, cause open sores on the skin of livestock which becomes irritating and annoying to the animals thereby causing them to reduce

*DOI: http://dx.doi.org/10.5772/intechopen.89738*

dermatophytes, etc.

histomonads (*H. melegridis*).

grazing and feed consumption.

aid fermentation of consumed herbage in the rumen [24].

#### *Farm Animals' Health Behaviours: An Essential Communicative Signal for Farmers' Veterinary… DOI: http://dx.doi.org/10.5772/intechopen.89738*

endotoxin—a deadly substance that causes disease in animals [23, 23]. Bacterial diseases of farm animals include botulism, paratyphoid, anthrax, brucellosis, foot rot, tetanus, etc. Bacterial diseases are however not as deadly as viruses as these could be readily treated with antibiotics, particularly when detected on time. Besides, not all bacteria cause disease as some are of great value in ruminant digestion where they aid fermentation of consumed herbage in the rumen [24].

In similarity to bacteria, fungi are widespread, exist in various shapes and sizes, and could survive in nearly all forms of environment, be it water, soil, air or in the mould on stale food and mushroom for a long period that runs into years. The micro-organisms are though ordinarily harmless, they cause disease in some situations which can be damaging or even devastating in some cases [17, 25, 26]. Some fungal diseases affect the mucous membrane (mucosal) though, most of them affecting the skin (cutaneous) by colonising and destroying their tissues [27]. Skin diseases are though rarely critical or deadly, their resultant irritation discomfort the animals leading to inhibition or disruption of their feed intake and consequently, a drastic drop in productivity [28]. Diseases of fungi could be highly contagious and primarily spread by direct contact between animals; with the clinically infected animals as the greatest source of infections [26]. Examples of fungal diseases include ringworm, aspergillosis, candidosis, mycotic, protothecosis, dermatophytes, etc.

Protozoa are single-cell microbes that survive both inside and outside living cells and could be found in most habitats. Most of the protozoa are though harmless and even play a vital role in controlling bacteria population and biomass; some are however parasitic pathogens of humans and animals [29] and as such significantly cause diseases in farm animals and even as potential drivers of zoonotic transmission [30, 31]. The parasites are a significant cause of abortion and infertility in domestic ruminants [32] and a relatively uncommon group of respiratory ailment [33]. Epidemiological situations of protozoan infection may occur as a single infection or zoonoses and may be sporadic in otherwise healthy hosts [34]. Also, infection of the nervous system is mostly fatal. An epidemiological situation that corresponds to pseudoepidemics occurs in a large host of the animal population due to a common source or poor housing conditions of the animals characterised by poor-quality or badly-stored bedding. Protozoan parasites in poultry are coccidia (species of the *Eimeria* genus), cryptosporidia (*Cryptosporidium baileyi*), and histomonads (*H. melegridis*).

Alongside the pathogenic micro-organisms causing diseases in farm animals are parasites that depend on the animals for growth and/or survival [34, 35]. The parasites may live and survive inside or outside the body of farm animals as internal and external parasites. Common parasites of farm animals exist as worms, flukes, protozoa, and insects such as lice, mites, ticks, flies. Unlike the parasitic protozoa, most parasites are visible to sight but some mites and worms can only be seen under a microscope at their early stages [16, 34]. With the dependence of the parasites on host animal(s) for survival, they may either inhibit the normal physiological functioning of the animals or act as a vector of other diseases thereby resulting in negative impacts on the health and welfare of animals. Such negative impacts, particularly by the internal parasites, may be manifested as anaemia as a result of substantial blood loss, reduction of the animals' appetite resulting in debilitating health and susceptibility of the animals to other diseases, diarrhoea and death of the animals arising from severity of the parasitic impacts [34, 36, 37]. The external parasites, on the other hand, cause open sores on the skin of livestock which becomes irritating and annoying to the animals thereby causing them to reduce grazing and feed consumption.

*Livestock Health and Farming*

**and diseases**

to diagnose [16].

**3. Sustainable livestock production and the challenge of animal pests** 

With development efforts in the livestock sector, world animal production has continued growing with increased productivity. Between 1995 and 2002, the world total meat production increased by 19%, the total milk production by 11%, and the egg production by 23% [9]. Notwithstanding the research support for the development and improved productivity of the livestock sector, the sustainability of livestock production is still being challenged by several production and environmental factors; with the degree of impact being influenced by the management system put in place by farmers. While farmers may try as much as possible to give their animals all the necessary care in terms of good housing units—spacious, dry and well ventilated, quality feeds and water, and necessary healthcare, it remains inevitable to completely prevent the incidence of pests and diseases in livestock management basically because of the impossibility of eradicating disease-causing pathogens which could survive in almost all avenue. Reduction of the incidence of pests and diseases in farm animal management has though been achieved by a combination of good hygiene, appropriate use of vaccines and medical therapy, and selection of disease-free breeds of livestock, the result is by no means an eradication of infectious and contagious diseases owing to the fact that a multiplicity of pathogenic agents are inducing emergence of complex diseases that may even be difficult

Pathogens, which are groups of organisms that cause diseases in farm animals, exist in form of viruses, bacteria, fungi, protozoa, and parasites, and are so small that they cannot be ordinarily seen by sight except with the aid of electronic magnifiers. These pathogenic micro-organisms or microbes exist in different sizes and shapes and are readily transmitted to animals through various substrates or vectors such as water, soil, waste or faecal matter, humans and animals [17–19]. Viruses are very small micro-organisms and much smaller than all other pathogenic organisms such that it can only be viewed with a strong electronic microscope [16]. However, the micro-organisms can only survive and/or multiply within living cells basically because it lacks cell membranes, cytoplasm, ribosomes, and other cell organelles [20, 21]. This mode of survival and multiplication by viruses make it possible to destroy the cells of the infected host thereby result in certain diseases. About 60% of animal diseases are caused by a virus and unfortunately, such viral diseases have no cure thereby resulting in the death of infected animals [17]. On this note, preventive actions, usually by vaccination, are required to ensure the healthiness of farm animals. Viral diseases of farm animals include foot and mouth disease, rinderpest, bluetongue, vesicular stomatitis, swine fever, fowl pox, avian influencer, etc. Bacteria, on the other hand, are relatively larger than viruses and also take different shapes and sizes but most are visible under an ordinary microscope. The micro-organisms, unlike viruses, could survive anywhere—within and outside living cells but could sporulate to form a protective coat that makes them survive in any environment for a long period, even years, and later cause infectious disease(s) in farm animals [16]. Bacteria that survive outside living cells could remain inactive until the emergence of favourable conditions to gain entry into the body of the animals, either through the skin or the eyes, breath into the lungs, consumed through food and water, to cause infections [22]. Similarly, some bacteria within the living cells, such as *Bacillus* and *Clostridium* species, envelope themselves with protective spores or endospores, which become dehydrated and highly resistant to an environmental condition such as heath, cold, or chemical compounds. The endospores, within which the bacteria may remain inactive for many years, produce

**28**
