Oilseed meals are commonly fed to pigs and poultry as sources of protein. The concentration and digestibility of amino acids in oilseed meals has been studied, but these ingredients supply other nutrients in the diet as well. Now researchers at the University of Illinois are providing a more complete picture of the nutritional value of oilseed meals.

A team led by Hans H. Stein, an animal sciences professor, evaluated canola seeds, canola meal, cottonseed meal, sunflower seeds and two types of sunflower meal.

The researchers conducted two experiments with growing pigs. In the first, they determined the digestible and metabolisable energy of each ingredient, and in the second they determined the standardised total tract digestibility of phosphorus with and without the addition of microbial phytase.

Professor Stein said: "From these results, we conclude that it is possible to include a number of different oilseed products in diets fed to pigs to meet the requirements for digestible phosphorus and energy.

“The current data provide feed formulators, nutritionists, and swine producers with the data needed to include different oilseed products in diets fed to pigs. Which ingredients are most economical to include in diets depend on local availability and cost."

The team based at Urbana-Champaign found that the concentration of digestible energy (per kg dry matter) in sunflower seeds (6,105kcal) and canola seeds (5,375kcal) was greater than that in soybean meal (4,518kcal) or corn (4,040kcal).

Canola meal, sunflower meal, dehulled sunflower meal and cottonseed meal contained less digestible energy (3,652, 3,238, 3,095 and 3,016kcal per kg dry matter, respectively) than soybean meal or corn.

Metabolisable energy values (per kg dry matter) followed the same pattern: 5,739kcal in sunflower seeds, 5,098kcal in canola seeds, 4,035kcal in soybean meal, 3,942kcal in corn, 3,306kcal in canola meal, 2,998kcal in sunflower meal, 2,860kcal in dehulled sunflower meal and 2,700kcal in cottonseed meal.

With no phytase added to the diets, the standardised total tract digestibility of phosphorus ranged from as little as 37.4 per cent in sunflower meal to 62 per cent in soybean meal. Phosphorus digestibility in sunflower seeds (51.7 per cent) and canola meal (58 per cent) was not different from that in soybean meal but the value for all other ingredients was less than in soybean meal.

The standardised total tract digestibility of phosphorus in all ingredients improved when phytase was added to the diets, ranging from 54.9 per cent in dehulled sunflower meal to 74.6 per cent in canola meal and 78 per cent in soybean meal.

“If phytase is added to the diets, the digestibility of phosphorus in canola seeds, canola meal and sunflower seeds is not different from the digestibility in soybean meal, but the digestibility of phosphorus in the other ingredients is less than in soybean meal,” Professor Stein explained.

The study, 'Energy concentration and phosphorus digestibility in canola, cottonseed, and sunflower products fed to growing pigs', was recently published in the Canadian Journal of Animal Science. Co-authors are Diego Rodríguez and Rommel Sulabo, both former members of the Stein Monogastric Nutrition lab, and current Ph. D. candidate Caroline González-Vega.

June 2014