The most productive pigs are likely to be those contained in a thermally neutral environment; that is, when the environmental temperature around the pig is insistently between the pig’s lower critical temperature (LCT) and upper critical temperature (UCT). The pig’s metabolic heat production is then at a minimum, and it is neither using feed energy to keep warm, nor reducing feed intake to keep cool.
Other considerations for pig comfort and well–being in addition to temperature are:
• Protection from other climatic extremes such as direct sun, wind and rain
• Provision of dry conditions which are hygienic and do not predispose the pig to disease
• Allowing, as far as possible, for inherent behavior patterns of the pig, and minimizing the effect of social dominance
• Provision of accessible feed and clean water
• Providing conditions so that good stockman can practice
• Effective disposal of effluent.
General considerations of pig house design
Any buildings, whether simple or complex, cost money, both to build and to maintain. This makes it imperative that careful thought is given to the right design, so that the investment is justified by improved
productivity. Moreover, considerations that affect design of houses in the tropics can be very different from those in more temperate parts of the world.
Under tropical conditions, the paramount consideration is generally to ameliorate the effects of excess heat. At the same time, it is important to minimise temperature variations, keeping as close as possible to the pig’s zone of thermal neutrality. This often involves keeping pig cool by even under tropical conditions; a separate creep area for the piglets which is warmer than the ambient temperature is generally an advantage, especially at night. This is because the optimum environmental temperature for the sow is between 16 and 18oC, whereas that of the newborn pig is 33-350C. A simple, enclosed creep box is perfectly adequate for the piglets to creep into and generate their own warmth by huddling together. If electricity or a paraffin source is available a light or simple heater can be provided in the creep box. This not only provides extra warmth, but attracts the piglets into the box and away from the danger of being crushed by the sow.
If separate arrangements are not made for the piglets and the whole furrowing room is warm, this reduces sow productivity. American work has shown that for every oC rise in temperature from 25o-30oC, daily feed-intake by the sow declines by 400grams.
Multi-purpose pig pens
These are liable to be more appropriate to the tropics and the developing world, as they are cheaper and more flexible. Removable structures, such as creep barriers and furrowing rails, provide protection for the piglets and make the pen suitable for furrowing. At weaning, these are removed, leaving a fattening pen in which the winners can be fattened
through to slaughter.
Follow-on pens
If specialised farrowing houses are used, sows can normally be removed into cheaper housing after 10-14 days when all danger of sow-related piglet deaths is past. Piglets then require a separate creep area, similar to that provided by a multi-purpose pen. This has the advantage of
allowing the sow to exercise and move around freely.
Weaner cages
The combined trauma of weaning from the sow and change in diet makes the young pig very susceptible to disease,particularly digestive diseases. This can result in fairly heavy mortality of weaners. The weaner cage was originally designed in Europe with the idea of providing conditions for the weaner which would help overcome these problems. Weaner cages have since been adapted for hotter climates and
basically consist of a covered solid-floor sleeping and eating area and a dunging area floored by either wooden slats or metal mesh during cold periods, pigs can huddle and generate enough heat for their comfort inside the covered kennel section. Ventilation is provided by the centrally-hinged roof of the kennel. In hot weather, pigs can keep cool by lying out on the meshed floors, and are protected from the sun by an umbrella roof over all the cages. As dung and urine falls through the wire mesh or slats, this can be cleaned from below and there is therefore no need for stockmen to enter the cage with contaminated boots, brooms or shovels.
Pigs normally remain in the cages for three to four weeks before being transferred to fattening accommodation. The feed hoppers can be moved to allow additional space as the weaners grow.
Weaner pools
The traditional system of housing weaners is to take litters of similar age and move them into large pens holding up to 50 weaners. After three�four weeks, pigs are batched into groups of equal sizes for transfer into growing / fatttening pens
Ample watering and feed trough space must be provided, and some form of bedding is preferable. Kennel area, which can be insulated by a ceiling of hay bales or wood, can provide for added warmth.
Growing / fattening accommodation
The basic needs for good fattening pens are relatively simple, namely, a dry lying area and a demarcated dunging area the building should provide shade, some protection and adequate ventilation. Solid walls are not required between pens, as they will decrease ventilation and flow within the building. Pens designed to hold 8-10 pigs through to slaughters are the ideal size.
Extensive systems
Extensive systems are particularly appropriate for sows. Sows are run in
paddocks and have access to ark or huts in which to farrow. In trials in Zimbabwe, sows were allowed a choice of different designs of arks at farrowing time, and it was found that they preferred a design similar to those found in the UK. The major difference is that under tropical conditions, the roof should be insulated with a 5 cm layer of grass or similar material. Arks can be constructed from cheaper materials, but it is difficult to make them sufficiently robust to avoid destruction by the sow. Ample deep shade and wallows should also be provided for sows run under this system. As mentioned previously, tethers can be used as a means of restricting sows within a paddock. They can then be rotated around a given area of pasture or other forage
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