Growing&Fattening
Pigs are transferred from the weaning units to the growing and finishing pens at a body weight of 25 to 30 kg. From now on they have to grow efficiently to be marketed at about 100 kg of body weight. The well-being of hogs during this phase has a major impact on their daily gains. They range from 0.5 to 0.6 kg.
Only penmates of the same weaning group should be placed in a pen to minimize the stress associated with the transfer. Familiar faces help to adjust to a new environment and changes in diet. Large scale hog feeder enterprises purchase pigs of different ages and from different sources. Fights among unacquainted penmates and infectious diseases are major problems. The immune system of a hog gets used to a certain bacterial and viral environment, which is specific for the farm the hog was reared on. When pigs from different farms are grouped together, they all bring their own specific microorganisms. Penmates, which are not adjusted to the pathogens may fall ill.
There are several ways of housing growing hogs. No matter what system, the environment has to be dry, warm and draft-free. Conventional barns are either totally closed buildings with forced ventilation and additional heating or insulated open-front buildings. The latter are open on one side, rely on natural ventilation and usually do not have additional heating. Feeding and watering facilities are located outdoors in concrete lots.
The floor surfaces of feeding pens are either partially or fully slatted or solid floors with or without bedding. About 15 to 20 hogs are grouped within one pen. According to the current US recommendations the minimum floor space per pig should be 0.92 m² at the beginning of the feeding period and 1.04 m² towards the end. Reduced space allowance has a negative effect on growth and social stability.
Uninsulated hoop structures have become popular during the last years, because of low investment costs. The roof is made of arched steel tubes covered by a polypropylene tarp. Both ends are left totally or partially open. Deep bedding (straw or wood shavings) provides shelter from the cold and absorbs the manure. Hoop structures may house 160 or more pigs, which are reared as a group. They are being weight on regular terms and all animals that meet the market weight are sorted out. Finally, when the barn is completely empty, the bedding is removed and the facilities are cleaned and disinfected until the next group arrives. This is called an all-in all-out management and it improves the health of hogs considerably.
Most pork farms produce their own feed by mixing home grown grain with a commercial protein-vitamin-mineral mix. While growing pigs usually have unrestricted access to feed, the rations must be limited when they reach a body weight of about 120 lb. At this point the consumed feed is rather converted into body fat than muscles. But nowadays most consumers prefer lean pork.
