Standardized total tract digestibility of phosphorus in bakery meal fed to pigs and effects of bakery meal on growth performance of weanling pigs

Two experiments were conducted to test the hypotheses that microbial phytase improves the standardized total tract digestibility (STTD) of phosphorus (P) in bakery meal and that corn may be replaced by bakery meal in diets for weanling pigs without negative effects on growth performance. Two sources of bakery meal were used in experiment 1 and one of these sources was also used in experiment 2. In experiment 1, eighty weanling barrows (initial body weight: 14.25 ± 1.91 kg) were allotted to a randomized complete block design with 10 diets and 8 replicate pigs per diet. Two basal diets based on each source of bakery meal (i.e., bakery meal 1 and bakery meal 2) were formulated without addition of microbial phytase. Eight additional diets were formulated by adding 500, 1000, 1500, or 3000 units of microbial phytase to each of the 2 basal diets. Pigs were housed individually in metabolism crates and feces were collected quantitatively for 4 d after 5 d of adaptation. Results indicated that greater increases in apparent total tract digestibility and STTD of P were observed in bakery meal 1 compared with bakery meal 2 when phytase was added to diets (interaction, quadratic, P < 0.05). In the second experiment, 160 newly weaned pigs (initial body weight: 7.17 ± 0.94 kg) were randomly allotted to 5 treatments with 8 pens per treatment and 4 pigs per pen. A 2-phase feeding program was used with d 1–14 being phase 1 and d 15–35 being phase 2. A control diet, containing primarily corn, soybean meal, and no bakery meal was formulated in each phase. Four additional diets in each phase were formulated by replacing 250, 500, 750, or 1000 g/kg of corn in the control diet with bakery meal. Results indicated that for the overall 5-wk nursery period, increasing concentrations of bakery meal tended (linear, P = 0.064) to reduce average daily gain and reduced (linear, P < 0.01) gain to feed ratio of pigs, whereas blood indicators of energy and protein utilization were not affected. In conclusion, digestible P in bakery meal may be increased by including microbial phytase in the diets, but a full replacement of corn with bakery meal in diets for weanling pigs may reduce growth performance.