Effects of type of fiber sources in the phosphorus-free diet on the endogenous losses of phosphorus in growing pigs

Abstract

An experiment was conducted to investigate the influence of fiber sources in phosphorus (P)-free diets on the endogenous losses of P in growing pigs. Eight barrows with an initial body weight of 37.4 kg (standard deviation = 2.7) were individually housed in metabolism crates. The animals were allotted to dietary treatments in a replicated 4 × 4 Latin square design with 4 diets, 8 animals, and 4 periods. Four P-free diets were based mainly on cornstarch, sucrose, and gelatin, and contained 10% purified cellulose, pectin, silica sand, or sawdust as a fiber source in each P-free diet. Each period consisted of a 4-d adaptation period and a 4-d collection period. Feces were collected quantitatively according to the marker-to-marker procedure. The feed intake of pigs fed the sawdust diet was less (P < 0.05) than that of pigs fed the silica sand diet. The total fecal output of pigs fed the purified cellulose or silica sand diet was greater (P < 0.05) than that of pigs fed the pectin diet. Fecal P concentrations were less (P < 0.05) in the pigs fed the purified cellulose or silica sand diet compared with the pigs fed the pectin diet. Total P output was not affected by fiber sources. The endogenous loss of P was 206, 350, 252, and 431 mg/kg dry matter intake (standard error of the means = 45.2) in the purified cellulose, pectin, silica sand, and sawdust diets, respectively. There were differences (P < 0.05) in the coefficient of apparent total tract digestibility of dry matter, organic matter, crude protein, ether extract, and calcium among experimental diets. In conclusion, fiber sources may have different effects on the endogenous P losses and the apparent total tract digestibility of nutrients.