Open access publications in the SLU publication database

Abstract

Pig feed is mainly based on cereals where phosphorus (P) is mostly present in inositol hexaphosphate (IP6), which is not readily available to monogastric animals. More available P sources are often added to ensure that pigs’ requirements are fulfilled; this results in high excretion levels of P. The digestibility of P depends on phytase activity and amount of IP6 in feedstuffs. The overall aim was to study effects of liquid feeding, P levels and phytase supplementation on digestibility and performance. Effects of soaking and P levels on digestibility were studied by total collection in metabolic cages, and effects on performance were studied in 192 growing pigs. Effects of soaking fermentation and phytase supplementation on ileal and total tract digestibility were studied with indicator technique on pigs surgically fitted with PVTC cannulas. P levels and phytase supplementation were studied in 104 pregnant sows for two reproduction cycles. All diets were cereal based and included wheat. Basic properties of a cereal mix fermented with whey, wet wheat distillers’ grain and water in different temperatures were also studied. Soaking reduced the level of IP6, whereas apparent digestibility of P was not significantly improved. Soaking increased average daily weight gain, carcass weights and improved the energy conversion ratio in pigs fed a low P diet to the same level as pigs fed high P diets. Low P diets resulted in lower femur density than high P diets. However, soaking of a low P diet resulted in increased femur density. Fermentation degraded IP6 efficiently and improved ileal apparent digestibility of P, organic matter, nitrogen, amino acids and total tract apparent digestibility of organic matter. Microbiological and biochemical properties of fermented liquid diets are strongly affected by feed components and temperature used. Phytase supplementation slightly affected apparent digestibility of P. Supplementing a low P gestation diet with phytase did not significantly affect sow performance. The slight effects of phytase supplementations found may depend on high levels of intrinsic phytase in the diets, and possibly suggest that the provided P level in the sows may have been sufficient. Under typical Swedish conditions of sow management, reduced total P level in gestation diets seems not to negatively affect performance.