FISH FARMING AND FISHERY REGULATIONS

In the same way as crops and livestock which are cultivated or raised on land, fishes can be reared for meat, oil and bone and fish meals. The practice of rearing fish meals. The practice of rearing fish in specially designated areas of land and water is referred to as fish farming (or fish culture). This practice requires a knowledge of the different species of fish, their growth requirements, and the conditions under which an optimal production of fishes can occur.

As a source of animal protein for man, fish farming is an important aspect of Agriculture. It is also important to the nation as:

(i)                 An avenue for providing employment;

(ii)               A source of foreign exchange earnings through fish exportation; and

(iii)             A source of vitamin-rich-oil, calcium and phosphorous (in the form of bone meal) and fish meal for livestock.

It is important, therefore, to learn about the different types of fish farming that can be practiced in Nigeria. It is equally important to learn and acquire some skills in site selection, establishment and maintenance of fish farms. All these points, including the existing laws regulations on fishing, will be the focus of this chapter.

At the end of this chapter, you should be able to:

(1)   Define fish farming and explain its importance;

(2)   List and describe the various types of fish farming;

(3)   State the conditions necessary for siting a fish pond;

(4)   Establish and maintain a fish pond or an aquarium; and

(5)   State the basic laws and regulations on fishing.

TYPES OF FISH FARMING

The practice of fish farming developed out of a human desire to control, with ease, the amount and availability of fish at a given period in time. Depending on the environment under which fish production is desired, several approaches can be adopted. Some of these approaches include ranch, pond, and cage cultures.

FISH RANCHING

This is similar to ranching of cattle on the range; but in this case fish are produced within an expanse of natural water. Fish ranching involves the fencing of bodies of water such as the coastal lagoons, streams, and rivers, to retain and restrict the movement of fishes contained there. The fence serves to restrict the movement of fish within the encashment (pen) area thus promoting efficient utilization of energy foods for body building and production.

In situations of high tides, fish from the open sea are washed into the pens and become retained within the fenced areas as the tides recede. The fisherman is thus able to harvest these fishes in addition to previous inhabitants of the ranch.

Little or no supplemental feeding is required in fish ranching, while water is naturally supplied all-year round from the rest of the body of water. Fencing is the major expenditure incurred in fish ranching, though the cost of preventing poaching (stealing) often adds to the production cost. How would you prevent poaching on a fish ranch?

PONDS

These are bodies of water which are naturally existing or are man-made for the purpose of rearing fishes. Fish-pond farming involves the selection of a suitable location, excavation of soil to create a water reservoir, continuous provision of suitable water, stocking, and maintenance of the pond to ensure optimum fish production. Pond culture provides for the effective control of breeding, feeding, poaching, and harvesting. This is because ponds have limited areas that can be easily managed.

The household aquarium of beautiful fish species is an example of a portable mini-fish pond. Can you list some privately owned fish ponds in your locality?

The productivity of a fish pond is usually higher than that of a ranch of similar area (size) because supplemental feeding, selected species combination, and good quality water supply can be maintained in ponds.

Cage Culture

This involves the rearing of fishes in specially constructed cages which are suspended in a body of shallow water such as lagoons, streams and rivers. This system capitalizes on the fact that if given water in which to swim and breath, and adequate feeding, fish would grow rapidly. That is, like birds raised in battery cages, fish in cages have restricted movement and adequate feeding which enables them to utilize nutrients efficiently for growth and production.

The cages can be made of palm fronds, bamboo, synthetic plastic or any other suitable material. They are usually suspended in water, stocked with desired fish species, and maintained till the fishes reach market size. In this way, the cage culture ensures effective protection of the farmer’s fishes and easy harvesting. It also ensures the regular supply of quality water to the fishes. Although the initial costs of cage production or procurement could be high, the returns on investment are however, very high. The profit margin in cage culture is much higher than in ranching or ponds.

A less popular type of fish farm which is sometimes found in the rice-producing areas of Nigeria is the integrated rice-fish farms. The rice and fish farm entails the stocking of rice paddies/fields (which are usually flooded) with fast growing fish species which are tolerant to low oxygen levels – e.g. Clarias spp or catfishes. Fish thus stocked are harvested with hand nets when the water is drained from the paddy in preparation for rice harvesting.

SELECTING SITE AND FISH SPECIES FOR A FARM

In the selection of a site for fish farming, certain environmental factors are considered.

These are;

(a)    Quantity and quality of water supply;

(b)   Type of soil;

(c)    Type and density of vegetation; and

(d)   Topography and ground elevation.

Water Supply. Water supply is an important factor in selecting a site for fish farming. This is because fish depend on water for all their needs, that is, to breathe, eat, grow, and reproduce. Thus, water must be available at all times and in good supply.

Water comes from many sources, e.g. rainfall, springs, rivers, the sea, and boreholes. Whatever the source of the water, it must be pollution and contaminant-free to support fish culture. A desirable water source is that which has high plankton population since most culturable fish species are planktivorous (i.e. feed on planktons).

Type of soil: The best   soil for a fish farm is one that contains a lot of clay. This is because the clay holds water well, it serves as a good diking material, and allows little water infiltration. Clayey soils also provide a suitable substrate for algal (planktonic) growth which most fishes feed on.

Type and Density of Vegetation: Sparse vegetation is normally preferred to densely forested areas because of the cost of site clearing. In addition, the amount of stumps and roots found in sparse vegetation is lower and can be completely removed; this becomes necessary to prevent decomposition which may reduce available oxygen and possibly change the acidity of the aquaculture to the detriment of growing fishes.

Topography and ground elevation: topography refers to the run of the land. For fish farming, a topography that allows the farmer to fill and drain the farm with ease is preferred. A gentle slope is most ideal for it allows for less excavation work in constructing the ponds. A survey of the site will indicate the elevation and the ways of ensuring the entry and exit of water to the farm.

CULTURABLE FISH SPECIES IN NIGERIA

Some of the culturable species of fishes in Nigeria are as follows;

1.      Clarias spp. (aro – Yoruba)

2.      Cbrysicbthys nigrodigitatus (Obokun)

3.      Gymnarchus niloticus (eja osan)

4.      Tilapia Sp. (epiya)

5.      Lates nilotica (giwa ruwan)

6.      Gyprinus carpio (Common carps)

7.      Heterotis niloticus

Some of these species of fish, e.g. Tilapia, are planktivorous and generally fast growing while others e.g. Gymnarchus niloticus are essentially predatory. Thus, for the purpose of rearing in fish farms, a combination of planktivores and predators is maintained to reduce supplemental feed supply and achieve a bigger Tilapia harvest. A stocking ratio of ten planktivorus to one predator is considered adequate for optimum production of both species in captivity.

The combination of culturable species on a fish farm is however, based on

(a)    Quickness of growth,

(b)   Shortness of the food chain,

(c)    Resistance to diseases,

(d)   Acceptance of available supplemental feeds,

(e)    Ease of breeding in captivity, and

(f)    Acceptance by consumers, that is, in terms of meat quality, taste, etc.

Establishment and maintenance of fish farms

The site available to a farmer often determines the type of fish farm to establish, for instance, farmers located around the coastal lagoons or along streams and river-banks usually exploit the natural water supply by establishing ranches or cage cultures. On the other hand, farmers located away from such natural water sources are able to produce fish only in artificially created ponds. Thus the type of fish farm to establish is dictated by the available water source.

Also, the species of fish a farmer can rear is determined by the quality of water available. This is because certain fish species are capable of growth in salty waters only while others will only thrive in fresh-water (e.g. heterotis niloticus, Clarias Lazera). There are however, compromise species such as Tilapia, which are capable of surviving in both salt and freshwaters, including brackish waters. In other words, the salinity of available water dictates the types of fish species to rear in a fish farm.

RANCH ESTABLISHMENT AND MAINTENANCE

The establishment of a fish ranch is probably the easiest among the three types of fish farming. This is because it only involves the use of wooden poles or bamboo and mesh plant materials or nets. The poles, usually about 2 metres in length, are spaced and forced down into the riverbed or shore bottom to demarcate the area of the farm. Mesh made of plant materials like palm leaves or net are then strung from pole to pole (to about I metrehigh on the poles),to form the enclosure (pen) which often times substends the river bank or shore.  

Where specific types of fish are not the production goal, the native fish fauna of the ranch may be allowed to breed and grow to harvest. If the converse is the case, the ranch is first depleted of its naïve fauna before the desired fish species are introduced (stocked); in which case, the number stocked must equal the amount recommended for the size of the ranch (i.e. the stocking capacity).

The subsequent maintenance of the ranch would involve provision of supplemental feeds and reinforcement of the fence to preven loss of stock or invasion of the ranch by predatory species from the surrounding waters. Aeration of the ranch is achieved by the movement of the surrounding water (in which oxygen dissolution continues undisturbed) in and out of the ranch. In this case, ‘spent’ water from the ranch is constantly replaced with oxygenated water of the surrounding waters.

The desire for easy and efficient harvesting of ranches has often led to the establishment of practical sized ranches. These are easily harvested at will using such tools as fish traps, drag nets, and cast nets. One major advantage of fish ranching is the production of fish and fingerlings on the same farm. Thus at harvesting mature fishes are selectively removed while the fingerlings serve to re-stock the ranch.

Cage culture and management

For cage culture, natural water sources like the lagoons, streams, and rivers are usually used. Cages of about 2 metre x 1 metre x 1 metre are constructed using suitable material such as bamboo. These cages are fitted with floats on the top-sides and suspended and anchored in water about three quarters way up. An opening is usually made at the centre of the top through which fish are stocked, and fed regularly (i.e. twice daily).

The flow of the water source in addition to the 0.25 metres space left on top of the cage enables adequate replacement and aeration of the cage water. Regular brushing of the cage sides is also carried out to prevent clogging by algae (plankton), which may reduce the movement of water in and out of the cage.

The species of fish encaged are usually surface feeders and fast growers (e.g. Tilapia, Carps). The stocking rate is determined by the cage size, but ranges from 200-300 fingerlings for the 2 x 1 x 1m cage. The restriction created by the cage, and the high quality feed (e.g. fish pellets) provided in cage cultures enables the caged fish to grow rapidly and make them ready for market within six months of stocking.

Harvesting is effected by lifting the cages out of the water and collecting the fishes. Unlike the ranch, only mature fish is harvestable in the cage culture; fingerlings and eggs produced by the stocked fishes usually get lost in the surrounding water through the tiny spaces left on the sides of the cage for water movement.

In comparative terms, the cost of cage construction and feed supply is much higher than that of fence construction and management in ranches. The productive ability of cage culture is however, higher than that of reaches. Cages are also amenable to movement from one spot to another with the stock they contain.

Establishment and maintenance of fish ponds

In establishing a fish pond, the factors considered in site selection must be taken into account. The farmer also takes into cognizance the type and size of a pond he can afford, and manage, and which meets his needs completely.

Preceding the construction of the pond, a survey of the land is carried out to determine the slope and thus decide the location of the pond’s main wall (normally located where the slope is greatest and marks the deepest part of the pond). A site with a slope of 2 – 5% is ideal for a fish pond. Next, the wall locations are marked out on the site and excavation work commences.

The depth of the pond depends upon the purpose and the growth of the fish. For instance, a nursery pond for fry is usually shallow (about 0.5m deep) while a production pond for adult fish is usually between 1.5-2 metres deep. Ponds should not be too deep, so as to allow adequate light penetration for plankton growth, and for easy harvesting.

The walls of the pond are then constructed so that their height is at least 30cm – 50cm higher than the water level to be maintained. Also, to make room for the ‘settling’ of the wall after construction, a 10% allowance is further given, so that a pond that is to contain 1.2m of water should have 1.2m + 0.3m + 0.15m (i.e. 10% of 1.5m) as a wall height or 1.65metres. the walls (also called dam dikes, levees or bunds) hold water within the pond; as such they must be made impervious (water-tight) to prevent leakage, and strong enough to withstand the pressure of the water inside the pond.

The drainage system is then established, using bamboo or plastic piping through the main wall of the pond. The pipe is located 30cm from the base of the wall; the end inside the pond is covered with a screen to prevent the escape of pond fish while the outer end is plugged with clay or wood which can be easily removed when the need to drain arises.

The inlet pipe, also of bamboo, plastic or other suitable material should be placed above the water level so that incoming water drops into the pond. This break in water flow enables the water to pick up (dissolve) more oxygen from the air.

If the site had a clayey soil of hard pan, it may be unnecessary to artificially seal the bottom of the pond and walls. However, where the bottom is sandy or gravelly, it should be made water-proof by lining with polythene sheeting or rubber wedged down with some soil.

On completion of the pond construction, it is then conditioned by placing a layer of lime (usually hydrated (builders) lime at the rate of 114kg/ha) at the bottom, about 2 weeks before the pond is filled with water. The lime helps fertilizers to be effective in the pond, and it controls the acid in the soil which may harm fish. After water filling, the pond is left to settle for a few days before it is tested for quality. This implies that the pond water is tested for temperature, oxygen content, pH, hardness, and alkalinity.

For a productive pond, the water temperature should usually range between 20^o and 35^oC, because at a higher temperature, the fish will not feed and will move slowly, resulting in poor growth.

Fish grow better between a pH of 6.5 and 9.0 and as such, the water ph should be maintained within this range and possibly go through liming. Also, like other living things, fish require an adequate oxygen supply for respiration. This can be maintained in pond water by stirring the water occasionally with a paddle or bubbling air into it artificially (i.e. aeration) or replenishing the water with fresh water.

Once the optimum hardness (of between 50 – 300 parts per million of dissolved salts such as calcium and magnesium) and alkalinity (of between 50-200ppm of dissolved carbonates and bicarbonates) is achieved along with the appropriate pH, the pond could then be stocked. Usually, 10,000 – 20,000 carps per hectare or about 20,000 tilapia per hectare is considered adequate in monoculture of these species.

Subsequent maintenance of the pond would include:

(a)    Daily feeding of the fish with foodstuff such as bread-crumbs, rice bran, fish meal, ground maize, broken rice, soyabean cake, sweet potatoes, groundnut cake, silkworm, pupae, fish pellets, and some animal manures. Occasional fertizers could be effected to promote plankton growth which later becomes a food source to pond fishes. It is important to provide only the amount of feed the fish can consume at the time of feeding because, excessive feeding may be injurious to the fish and leftover feed may or could tie-up pond oxygen through decay oxidation. 5% of the fish body weight should be fed daily for six days a week,

(b)   Checking the pond for leaks,

(c)    Watching fish behavior near the feeding area to determine if there is any stress on them as a result of low oxygenation of pond water, which may then imply need for replenishment,

(d)   Watching for predators such as crabs, eels, strange fish, and snakes,

(e)    Improving the water quality through the addition of lime.

FISHERY REGULATIONS

There are two sets of regulations, governing fishing and fishery. These can be classified as

(i)                 International regulations and

(ii)               Local regulations.

For our purpose, it is sufficient to summarize international fishery regulations as those which

(a)    Defines national fishing zones (preserves) as that 100 nautical miles of water sub-stending the  national land mass;

(b)   Declares bodies of water outside this national fishing zone as international fishing areas;

(c)    Forbids nations of the world from mining or polluting international waterways; and

(d)   Forbids the killing of near-extinct aquatic animals such as certain species of whales, seals, etc.

On the local level, the Nigerian government have regulations which

(i)                 Forbids the harvesting of fish by poisoning (e.g. with gammalin 20) or dynamiting (with explosives) both of which pose health hazards to human consumers;

(ii)               Forbids industries and manufacturers from discharging factory waste into streams, or rivers, which serve as a source of water to fish farmers or as a source of drinking water to other communities upstream.

Summary

In this chapter, you have learnt that:

1.      The practice of rearing fish in special or artificially created areas of land and water is known as fish farming.

2.      Fish farming is important for the production of fish which is a source of animal protein, vitamin-rich oil, calcium and phosphorus as well as fish meal for livestock.

3.      Three types of fish farming exist in Nigeria, ranching, cage and pond cultures.

4.      Water source and supply, soil type, and topography are some of the factors to be considered in site selection for fish farms.

5.      Combination of culturable species of fish for farms are based on quickness of growth, resistance to disease, ease of breeding in captivity, acceptance by consumers, and feeding habit.

6.      About procedures for the establishment and maintenance of ranch, cage and pond cultures.

7.      Regulations are established which specify national fishing zones, international fishing zones, and forbids use of poisons and dynamites for harvesting fish.

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RABBIT PRODUCTION

INTRODUCTION

The domestic rabbit (Oryctolagus cuniculus) has long been associated with man and has contributed to his well-being for many centuries. It is used as food, as an experimental subject in research, for fur production, and is a source of much pleasure as a pet and fancy animal. The rabbit adapts to a great variety of environmental conditions and is found in the wild and domesticated states on every continent.

Rabbit production as an industry is small when compared to the amount of meat produced, and the monetary income derived from poultry and the other livestock industries. However, the contributions of rabbits to research, the aesthetic value of its fur, and the pleasure provided to owners as pets and fancy animals make rabbit raising far more beneficial and significant than its economic value alone.

Most rabbit production units are small, thus many families and individuals are involved. The capital investment needed to begin raising rabbits is not large when compared to that needed by most other livestock industries. The amount of land, equipment and other items required is relatively small. Since the space requirement is not much, it is often possible to raise rabbits near the home on rather small acreages.

Production purposes

1.      Meat

2.      Research and laboratory

3.      Show and fancy.

4.      Youth projects

5.      Miscellaneous uses – pleasure, pets, etc.

Meat

Most domestic rabbits are slaughtered for food. Rabbit meat is of high quality, white, appealing and tasty, and tender. The dressing percentage of good quality rabbit is about 60%. Rabbit meat may be cooked in a number of ways, and traditionally it has been prepared in most of the same ways as poultry. The young 8 – week old rabbits are referred to as fryers while the mature rabbits are called roasters.

RESEARCH AND LABORATORY

Rabbits possess many characteristics similar to other species of mammals. The domestic rabbit has been and continues to be used in a variety of experiments both biological and medical, as well as in a variety of physiological, disease, nutritional, and other types of studies. The  unique characteristic of induced ovulation and the habitual practice of coprophagy (eating of faeces) are of special importance in certain types of research. There is therefore a market demand for rabbits as laboratory animals and many producers raise rabbits only for this purpose. This is of course a specialized activity.

SHOW AND FANCY

Some people are interested in and produce rabbits entirely for the pleasure of breeding and showing fancy animals; and there are a number of breeds which are considered fancy breeds and are seldom sed for other purposes. Such shows not only provide pleasure and a means of exchanging information but also provide an incentive for genetic improvement and good quality rabbit production.

MISCELLANEOUS USES

Associated with the production of rabbits for show and fancy, is the pleasure they provide as pets. Pelt production is not a primary objective of raising rabbits, but rabbit furs are used in the manufacture of clothing. Pelts (skin of fur-bearing animals, used as garments) from some breeds are highly prized for making coats, gloves and other items, and those from the slaughter of fryer rabbits are generally used in the manufacture of Pelt (fabric of wool, often mixed with fur or hair, worked together with pressure, heat, chemical process, etc., without weaving or knitting).

THE ATTRACTIVE PROPERTIES OF RABBIT FARMING

1.      Rabbit production requires relatively low capital to start.

2.      Feed cost is minimal as rabbits depend extensively on forages; feed materials are mostly obtained free of charge, or at minimal costs.

3.      Generation intervals and maturity periods are short and as such, in the face of animal protein shortages in Nigeria, the potential of rabbits to augument the total animal protein supply in Nigeria is indeed quite high.

4.      Rabbits are neat, non-smelly and non-noisy animals, and as such can be kept near human houses, school buildings or even around offices without causing health hazards, particularly through environmental pollution.

5.      Because of the small size of rabbit a family can use a rabbit for “one meal” thereby not requiring storage facilities.

6.      Rabbit has a “popular choice” advantage because there are no known taboos restricting the production and consumption of rabbit.

7.      Rabbit meat is white meat, a source of high quality protein, low in fat, and therefore has low tendency to deposit cholesterol. The meat is recommended for people who have heart problems and those convalescing after sickness.

8.      It is a good research animal, particularly in medicine since it possesses a physiology similar to that of man.

9.      Basic skills of livestock  rearing are easily acquired with rabbit rearing. Rabbit responds to careful handling but can withstand the occasional rough handling of a beginner.

10.  Rabbit is friendly and harmless and therefore can be handled by the handicapped who enjoy caring for and managing them.

HANDLING OF RABBITS

To appreciate the need for proper handling and a good knowledge of the appropriate handling techniques are veritable instruments for an effective management of rabbits. Wrong handling method is a source of stress to the rabbit and this can up-set its temperament and make it cruel. This situation becomes more obvious because the skeleton of rabbit is not strong and in case of sudden drop of a ro   its backbone may break causing paralysis.

There is varying temperame between and within breeds of rabbits. While some domestic rabbits are docile and easy to handle, some others are aggressive and resort to biting.

It is wrong to chase a rabbit round its hunch. The correct approach is for the farmer to use a board to trap the rabbit in a corner of the hutch.

Farmers should avoid lifting rabbit by its ears because it is painful, and may cause stretching of the ears at their bases and they may droop when they should be erect.

During handling, rabbits should be talked to in a soothing voice.

METHODS OF HANDLING/HOLDING RABBITS

i.                    Scruff method

ii.                  Pelvis method

i.                    The Scruff Method

In this method, the handler must trim his finger nails. The rabbit should be lifted by the skin behind the ears and supported by placing the other hand under the hindquarters. The farmer should avoid struggling and kicking.

ii.                   The Pelvis Method

This method is recommended for young rabbits only. in this method, the young rabbit is lifted by the pelvis or skin and quickly transferred either from hutch to basket or vice versa.

TRANSPORTING RABBITS

If rabbit is to be transferred for short distances, it is easier for the handler and more comfortable for the rabbit to be held close to the handler’s body. In this practice it is common to see rabbit tucking its face into a corner of the handler’s arm. On the other hand, if rabbit is to be transported to long distances, provision should be made for a “transport box” which should be fairly dark inside but ventilated. The box should preferably have a cover (lid) and the box possibly kept inside the hutch to accustom rabbit before transport. There is need to clear and disinfect the transport box each time it is used.

THE ENVIRONMENT OF RABBIT

Like every other animal, rabbit interacts with its habitat. The elements of rabbit environment include:

-          The rabbit keeper

-          The rabbit itself

-          The hutch micro-climate: temperature, humidity and air movement.

-          The hutch space

-          Predators such as snakes, gods, etc.

It is good practice for a rabbit keeper to modify the rabbit environment with a view to providing optimum circumstances for production.

The rabbit employs some behavioural factors in the environment, e.g. when the ambient temperature is high, the rabbit stretches out itself to lose heat but when too cold, It curls up. When it breathes faster, it increases blood circulation to the ear. When the rabbit feels too cold, it curls up to keep itself warm, while it quickly runs and hides at the corners if it is frightened or disturbed.

HOMEOTHERMY

The domestic rabbit is a homeotherm because its body temperature swings within specific limits in order to keep alive. The normal temperature of the rabbit (rectal temperature) is 37 – 39.5⁰C (99 – 103⁰F). The body temperature is maintained by burning or breaking down food in its body or by working to keep warm e.g. by shivering. The ambient temperature determines the gain or loss of heat by rabbits. It excess heat is promptly dissipated, the animals gains an excess heat load which consequently causes “heat stress”.

Methods of Heat Loss in Rabbits

(a)    Evaporation of moisture from the body surface.

(b)   Conduction: This method involves the loss of heat through solid material e.g. heat of the rabbit feet is conducted by the hutch floor.

(c)    Convection: Heat is lost through convection when the body heats up air and the air moves away heat from the rabbit.

(d)   Radiation: This involves the loss of heat in direct waves from the body.

HEAT STRESS

Heat is a critical constraint to rabbit production because rabbit is not adequately adapted for rapid heat loss.

Heat stress is mostly initiated by sudden rise in ambient temperature to which the rabbit cannot easily acclimatize. Other causes of heat stress include: exposure of rabbit to direct sunshine which causes the rabbit to admit more heat from the sun than the rabbit can tolerate. The rabbit finds it difficult to lose heat thus building up its heat load and subsequently stress results. Also, the construction of rabbit hutches with metals such as tin could make the hutch always too hot especially during the dry season or on sunny days. This affects the temperature of the rabbit, thus subjecting it to stress. Absence of shade exposes the hutch to much heat of the sun. if, however, there is free air movement, the temperature moderating effect is guaranteed. The absence of shade and restricted air movement also contributes substantially to heat stress in rabbits.

The prevailing circumstances is that the rabbit may be unable to lose enough heat thereby causing its rectal temperature to rise above the normal range thus causing heat stress.

Effects of Heat Stress

i.                    Ambient temperature above 20⁰C causes reduction in food intake.

ii.                  There is increase in water intake arising from the need to reduce the rabbit’s body temperature.

iii.                Growth rate or rate of gain reduces.

iv.                When the ambient temperature is above 25⁰C, there is impaired reproduction.

PHOTOPERIODISM

In temperate regions, sexual activity of the wild rabbit is known to be affected by changes in day length. Photoperiod stimulates the commencement and cessation of reproduction. Changes in day length are not significant in the tropics and their effects are not known. However, keeping a rabbit in a dark environment will cause a cessation of reproduction.

BIOLOGY

Biological characteristics of the rabbit in terms of gross anatomy and physiology are similar to those of other domestic animals. In terms of growth, new born rabbits grow rapidly and more than double the birth weight by one week if the doe is lactating normally. At 2-4 weeks, when growth is still dependent upon the mother’s milk, the weight is approximately 12% of the adult weight. By 8 weeks, the weight approaches 40% of the mature weight.

The females are larger than males in most breeds and weights shown after 8 weeks reflect this.

Milk production of the doe and the number of young per litter have a major effect on early growth. At 6 weeks of age, when most of the weight is dependent upon milk consumed, the weight of individual young in a litter of 8 or 9 will be about 80-85% of the weight of the young in a litter of 4.

The rabbit has been referred to as pseudo-ruminant, but the digestive system doe not function like that of ruminant and is rather characteristic of monogastric animals.

The term ‘pseudo-ruminant’ has been applied to the rabbit because it consumes and recycles a portion of its fecal matter (coprophagy) during which process certain nutrients synthesized in the lower intestinal tract including ceca in colon are made available to the rabbit. Digestion of food nutrients takes place under the influence of enzymes as is characteristic of other monogastric animals. Significant synthesis of some of the B-vitamins and possibly some amino acids takes place in the lower intestinal tract (primarily in the cecum and large intestine, by microbial action).

Since the rabbit is herbivorous, consuming the vegetable portion of plants as well as the seeds, it is assumed that the rabbit can digest and utilize significant amounts of crude fibre. Actually the rabbits digests relatively small amounts of fibre, probably less than 20%. The fibre digestion however, does not take place in the cecum, since when the cecum is removed, there is little or no change in the amount of crude fibre digested by the rabbit although there is a decrease in vitamin synthesis.

Coprophagy

Copra refers to the act of eating faeces and is a normal practice in rabbits. Animals that practice coprophagy are able to obtain some nutrients, especially water soluble vitamins, which have been synthesized by micro organisms living in the intestinal tract. Rabbits excrete two types of fecal matter: the dry, hard rounded pellets normally observed, and a moist jelly-like material referred to as the soft or night faeces. It is this soft faeces that the rabbits recycle, collecting it directly from the anus as it is excreted. It is not common to see the rabbit consume this soft faeces, it is necessary to collar the rabbit or restrain it in some way.

Coprophagy in the rabbit has been referred to as pseudo-rumination. It aids in digestion but does not correspond to the rumination process characteristic of other ruminants. It is thought that the soft faeces form in the cecum and rapidly pass out through the large intestine with a little time for a change in consistency; hence they appear as clusters, each pellet is surrounded by a membrane. The soft faeces has a higher vitamin and crude protein level than the hard faeces. Thus the practice of coprophagy by rabbits is perfectly normal and is an advantage in digestion and in supplying additional B-vitamins.

If the cecum is removed, coprophagy is not practiced, but both types of faeces are still excreted.

FEEDING

The efficient production of rabbits is largely dependent upon adequate and proper feeding. Feeds make up a large component of the major costs of animal maintenance and of meat production. The quantity of food provided is important, but the quality or type of feed is equally or more important. Poor nutrition can result in slow growth, inefficient reproduction and predisposition to diseases.

In order to provide adequate feeds, a knowledge of the requirements for each nutrient is necessary. When the requirement for any nutrient is not met, the animal may not grow or reproduce normally and may eventually die. On the other hand, supplying in excess amount of a nutrient is neither necessary nor economical. The need therefore to supply a balanced diet cannot be over emphasized. Nutrient requirements vary with age or stage of growth and the reproductive function of the rabbit; maintenance, pregnancy and lactation. The rabbit is a herbivorous animal, subsisting on feeds of plant origin, grass or vegetable type plants in the growing season, and hay or dry forages and seeds in the dry season.

Although rabbits can live and reproduce on these bulky type roughage feeds, some concentrate feed is required for efficient growth and reproduction. At the present, a commercially prepared pelleted diet is available for rabbits.

Housing

The most widely used type of housing is a shed or other structure fitted with cages. The size of the building will depend on the number of rabbits kept. In warm climates, the building may consist primarily of a shed which protects the rabbits from rain and direct sun. various construction materials are used, including wood, aluminum and steel.

The building floor is an important consideration. Most commercial rabbitries have concrete floors, and the area directly under the cages usually consists of a drainage bed from which fecal droppings and effluents are removed periodically. Where litter pans are provided, the floors may be concrete but Sloped For Drainage.

The cages or hutches may be arranged in a number of different ways inside the building. The common arrangement consists of rows of cages, with two rows opening onto a central walk path, which should be wide enough to allow feeding, servicing and watering. Where multiple tiers of cages is in use to make for more efficient use of space within the building, litter pans must be used (placed under each row of cages) to ease manure removal and cage cleaning. A sheet of metal sloping in such a way that water can be used to remove the manure, may be used in place of litter pans. Efforts must be made to prevent entry of rats and other pests into the building, and yet allow for maximum ventilation. Cage sizes vary depending on the breeds being kept, but cages must be large enough for rabbits to make normal posturing adjustments and to provide adequate freedom of movement.

The material most used for rabbit cages is woven wire. Stainless steel cages are used primarily in the laboratories. These are much more expensive but are non corrosive and last for longer periods.

Two measurements are needed to identity wire used for rabbit cages; the grid or mesh, and the guage or the diameter of the strand of the wire. Grid or mesh refers to the size of openings between strands of wire, while guage is the size or diameter of the strands of wire. One half inch (2 x 2 mesh) means that the openings are ½ inch, or 2 openings per linear inch. With guage, the larger the guage, the smaller the wire.

Particular attention should be given to the mesh and guage of wire to be used for the floor of the cage. Grid openings must be large enough to allow faeces to pass through readily, but small enough to provide comfort and prevent the faeces from becoming entangled.

HOUSING REQUIREMENTS

Adequate space

The rabbit hutch should be constructed in such a way that the rabbits should have adequate space for free movement. This measure is intended to avoid stress imminent when the movement of rabbits is restricted in hutches. Space, both vertical and horizontal is a critical factor in ensuring adequate ventilation and temperature control within the hutch as well as keeping the animal comfortable and free from disease outbreaks.

Protection or Safety in the Hutch

A good hutch should be capable of protecting the rabbit from injury, rain, direct rays of sunlight, wind, sudden noise and predators such as snakes, dogs, cats, rats and human thieves. 

Convenience and ease of Management

For effective management of the rabbits, a hutch should be designed to assist the farmer in observation, feeding, breeding the rabbits a hutch should be designed to assist the farmer in observation, feeding, breeding the rabbit, cleaning and disinfection. At the age of 3 months, the males should be separated from the females while arrangements should be perfected to create one rabbit per hutch.

Materials for building a rabbit hutch

The floor must permit easy drainage of both urine and faeces of the rabbits. Wooden materials could be used for building the floor, frame and roof while the sides could be covered with wire mesh for easy ventilation and screening out predators. However, hay could be placed on the floor as bedding material.

PHYSIOLOGY OF RABBIT REPRODUCTION

Heat (Estrus)

Unlike most farm animals, rabbits do not have a regular estrus cycle. The heat continues for a long period until doe is bred. This situation is caused by the fact that the follicles on the ovary remain active for at least 12 days before regressing. At regressing, others become active to take their place – within 1 to 2 days.

The doe is usually receptive when placed with the buck. This receptivity is signaled by some signs of estrus.

Signs of Estrus

i.                    The vulva appears red and swollen.

ii.                  Restlessness.

iii.                The doe tries to join other rabbits in adjacent hutches

iv.                The doe rubs her chin on the floor

v.                  An estrus doe raises her hindquarters when placed with the male.

When the buck mounts the doe, he grasps the doe with his forelegs. The buck achieves intromission after 8-12 rapid copulatory movements while ejaculation is made following the first intromission. In many cases, after ejaculation, the buck falls off to one side and could make a crying noise while a vigorous buck will make an attempt to mount again. The fluid portion of the ejaculate ranges between 0.5 and 1.5ml and the sperm density ranges between 0.5 x 10⁶ and 3.5 x 10⁶ml. extreme temperatures or those above the tolerance level reduce sperm count and this situation can be remedied by adding thyroxine to rabbit diet. About 10-13 hours after mating, the doe drops her eggs. Thus breeding the doe can take place morning and evening of the same day.  This practice increases the litter size. After breeding, some does will stop to ovulate, particularly those associated with a deficiency in Luteinising hormone (LH). The regulation of the doe’s weight through feeding is vital because fat does are not good breeders.

Ovulation

This is the process of egg release. Ovulation is the process of large overian follicles breaking away to become an egg, usually after about ten hours following mating.

Within this period, the spermatozoa have moved through the female reproductive tract to the oviduct where fertilization takes place.

DEVELOPMENT OF THE FOETUS

After fertilization, the fertilized egg (zygote) grows into a foetus. As many as 10 eggs can be shed at the same time in doe of high reproductive efficiency, while as low as 4 eggs may be shed in low productive does. The gestation period of rabbits is within the range of 28 to 35 days.

Breeding methods

Breeding Age

Smaller breeds develop faster and attain sexual maturity earlier. The bucks for breeding should be at least one month older than the doe at first breeding. Does weighing 4-6kg should be bred at 5-6 months of age, while larger breeds of 8 -10kg should be bred at 8-10 months.

The doe should be taken to the buck’s hutch or cage by good handling methods and observed for up to 20 minutes. If mating does not take place, another should be tried, or the same buck tried the next day.

Kindling (giving birth to young)

Parturition in rabbits takes place usually in the early morning hours. Parturition in rabbits is called kindling. As preparation for kindling, the doe makes nest with available hay or straw. She further plucks her hair and lines the nest. At parturition, the doe eats the placenta and foetal membranes. 

SOME ABNORMAL BEHAVIOR OF THE DOE

i.                    Failure of the doe to build a nest

ii.                  Birth of the young outside the nest

iii.                Cannibalism

iv.                Scattering the young

v.                  False pregnancy

The average litter size of rabbits is 8 kits which should reach the weight of 10-12kg at three months of age at which age they are mostly slaughtered for.

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