Improved performance, but beware fat
PIG producers now vaccinating stock against enzootic pneumonia must consider its effects on performance when formulating rations.
Speaking at an SCI amino acid nutrition conference in London, Wokingham-based pig consultant William Close, said pig rations must be designed according to the herds potential for lean deposition, genotype, appetite and health status, all of which affected the animals potential growth rate.
One of the main problems was health status, which affected the ability of the animal to grow. The recent introduction of an enzootic pneumonia vaccine had improved animal performance on some units.
"These animals eat more, grow faster and deposit lean, but they have the energy to deposit fat as well," said Dr Close.
"This must be taken into account when specifying rations for individual farms.
"Increasing the supply of feed protein increases protein deposition up to a certain level and energy is also a limiting factor. Increasing the energy supply allows pigs to achieve their genetic potential," he explained. There was also a variation in the proportion of lean and fat deposition in different breeds, although the animals could achieve the same daily weight gain.
Genetic selection had also reduced appetites and the ability of animals to perform at higher levels, he claimed. If pig appetites had been greater the response to feeding would have been greater.
Reduced intakes and increased maintenance needs had made rationing harder. "We have to get feeding absolutely right for animals to perform," he said. That included an allowance for maintenance feeding – the higher the level of feeding and performance the higher the maintenance needs. But the difference in protein deposition could be small, providing sufficient nutrients were supplied for the pigs pattern of growth.
Dr Close also questioned the feeding efficiency of using only two diets in the growing period. This meant there were long periods of either over or under-supply of nutrients because every day the animals requirements changed. *