Protein digestibility of grain, oilseed co-products examined for young pigs

Digestibility only part of the picture; total protein concentrations also need to be considered.

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Co-products from the grain milling and oilseed industries can be included in swine diets for pigs, but limited data exist on the digestibility of protein in many of these ingredients when fed to younger pigs, according to the University of Illinois.

Research at the university is giving producers more information about the feeding value of grain and oilseed co-products fed to young growing pigs, an announcement said.

A team led by Hans H. Stein, professor in the University of Illinois department of animal sciences, determined the standardized ileal digestibility (SID) of crude protein and amino acids in brewers rice, full-fat rice bran, defatted rice bran, peanut meal, sesame meal, rapeseed meal, rapeseed expellers, soybean expellers, cassava meal and bakery meal fed to pigs starting at a weight of 14 kg.

The results, published in the Journal of Animal Science, indicated that the SID of crude protein and amino acids was greatest in brewers rice (with 93.7% crude protein digestibility) and sesame meal (88.5%) and lowest in cassava meal (30.2%).

The SID of crude protein and most amino acids was equivalent for rapeseed meal, rapeseed expellers and soybean expellers; SID of crude protein ranged from 78% to 82% in the three ingredients, Stein said. The SID of arginine, isoleucine, leucine, lysine and methionine was greater in full-fat rice bran than defatted rice bran, but the SID of crude protein and other amino acids did not differ between the two rice co-products.

Still, Stein pointed out that digestibility is only part of the picture. "To determine how much digestible protein was available to the pigs from each ingredient, we also had to take into account the total protein concentrations in each one," he said.

When adjusted for the total amount of protein and amino acids in each ingredient, the researchers found that sesame meal contained the greatest concentration of SID of crude protein (482.32 g/kg dry matter) and most amino acids. Peanut meal contained 452.38 g/kg digestible crude protein, followed by soybean expellers (351.33 g), rapeseed meal (286.64 g), rapeseed expellers (262.74 g), defatted rice bran (119.50 g), full-fat rice bran (112.19 g), bakery meal (76.63 g), brewers rice (73.87 g) and cassava meal (6.93 g).

However, due to the relatively low digestibility of lysine in sesame meal and peanut meal, Stein said soybean expellers, rapeseed meal and rapeseed expellers contained more digestible lysine.

"Based on these results, we conclude that sesame meal, peanut meal, rapeseed meal, rapeseed expellers and soybean expellers are excellent sources of digestible protein and amino acids. The last three are especially good sources of lysine," Stein said. "At the other end of the spectrum, brewers rice, bakery meal and cassava meal contain little digestible protein and amino acids, so they’re mainly a source of energy."

The paper, "Ileal Digestibility of Amino Acids in Selected Feed Ingredients Fed to Young Growing Pigs," was published in the Journal of Animal Science.