Rojas, O. J. and H. H. Stein. 2013. Phosphorus digestibility and concentration of digestible and metabolizable energy in corn, corn co-products, and bakery meal fed to pigs. J. Anim. Sci. 91(Suppl. 2):122 (Abstr.) Link to abstract (.pdf)

Rodríguez, D. A., R. C. Sulabo, J. C. González-Vega, and H. H. Stein. 2013. Energy concentration and phosphorus digestibility in canola, cottonseed, and sunflower products fed to growing pigs. J. Anim. Sci. 91(Suppl. 2):116-117 (Abstr.) Link to abstract (.pdf)

Almeida, F. N., R. C. Sulabo, and H. H. Stein. 2013. Effects of a novel bacterial phytase expressed in Aspergillus oryzae on digestibility of calcium and phosphorus in diets fed to weanling or growing pigs. J. Anim. Sci. Biotechnol. 4:8. Link to full text (.pdf)

Research has shown that grinding cereal grains in diets fed to pigs into smaller particle sizes improves growth performance. Feed ground to smaller particle sizes has more surface area on which digestive enzymes can work, so digestibility of energy and nutrients that are enzymatically digested may also  improved. Generating specific data on energy and nutrient digestibility will help determine the optimal particle size for feed ingredients.

An experiment was conducted to determine the concentration of digestible and metabolizable energy and to measure the apparent (ATTD) and standardized total tract digestibility (STTD) of phosphorus by growing pigs fed diets containing corn that was ground to different particle sizes.

Soybean meal is a high quality source of protein for swine diets. Due to the growth in global production of pigs and poultry, demand for soybeans is increasing rapidly, outpacing production. Therefore, other sources of plant protein are sometimes used in diets to supply indispensable amino acids to the animals.
The most abundant oilseeds produced in the world, aside from soybeans, are cottonseed, canola seed (rapeseed), and sunflower seed. These oilseeds may be fed as de-oiled meals, or the full fat seeds can be fed to increase the energy concentration of the diet.

Oilseeds and oilseed meals also provide phosphorus to the diet. However, most of the phosphorus in these sources is bound to phytate, and is not available to pigs. An experiment was performed to determine the standardized total tract digestibility (STTD) of phosphorus in canola, cottonseed, and sunflower products, and to discover how the addition of phytase influences the STTD of phosphorus. The apparent total tract digestibility (ATTD) of calcium and the effect of adding phytase on ATTD of calcium were also measured.

Rojas, O. J. and H. H. Stein. 2012. Digestibility of phosphorus by growing pigs of fermented and conventional soybean meal without and with microbial phytase. J. Anim. Sci. 90:1506-1512. Link to full text (.pdf)

Kim, B. G., J. W. Lee, and H. H. Stein. 2012. Energy concentration and phosphorus digestibility in whey powder, whey permeate, and low-ash whey permeate fed to weanling pigs. J. Anim. Sci. 90:289-295. Link to full text (.pdf)

By Dr. Hans H. Stein

November, 2011

Microbial phytase is often used in diets fed to pigs because it is well established that the digestibility of phosphorus in many ingredients is increased if microbial phytase is used in the diet. The reason for this increase in digestibility is that microbial phytase has the ability to release some of the phosphorus that is bound in the phytate complex in many feed ingredients. Without phytase in the diet, most of the phytate-bound phosphorus is not digested by the pigs and is instead excreted in the manure.

Meat and bone meal (MBM) is a product of the rendering industry composed primarily of the offal and bones of slaughtered livestock, fat from unmarketable animal tissues, unsellable retail meat products, and whole condemned carcasses (excluding hair, blood, hooves, horns, and contents of the gastrointestinal tract).  MBM is traditionally used as an animal protein source in swine diets, but because of its high concentrations of calcium and phosphorus, it can also replace inorganic phosphates in swine diets.

The proportions of soft tissue and bone in different sources of MBM can vary widely. Because mineral digestibility differs in bone and soft tissue, the variation in composition of MBM sources leads to a variation in mineral digestibility values.

An experiment was conducted to 1) determine the apparent (ATTD) and standardized (STTD) total tract digestibility of phosphorus and the ATTD of calcium in 8 different sources of MBM,  2) estimate variation among MBM sources, and 3) develop equations to predict the concentrations of digestible phosphorus and calcium in MBM.