Distillers dried grains with solubles (DDGS), a co-product of the ethanol industry, is becoming a more common ingredient in swine diets. However, DDGS can be high in sulphur, and data are limited on the amount of sulphur that pigs can tolerate in the diet. Therefore, researchers at the University of Illinois (U of I) have conducted research to investigate effects of high levels of sulphur in diets for pigs.

"The sulphur content of DDGS can range from approximately 0.3 to 0.9 per cent," explained Hans H. Stein, professor of animal sciences at U of I.

"In a previous study, we determined that you can feed diets containing up to 0.38 per cent sulphur without affecting palatability or pig growth performance. We wanted to follow up by determining whether or not the quality of the carcass was affected by the sulphur in the diets."

Professor Stein's team used a source of DDGS that contained 0.3 per cent sulphur. One of the experimental diets in the study contained this low-sulphur DDGS at an inclusion rate of 30 per cent. The other diet had calcium sulphate added to simulate the use of high- (0.9 per cent) sulphur DDGS. The sulphur content of the second diet was 0.38 per cent.

Carcass length, 10th-rib fat depth, loin area and fat-free lean were the same among pigs fed the control, low-sulphur and high-sulphur diets when adjusted for hot carcass weight. No effect on organ weights, loin quality, loin pH, drip loss, loin subjective colour, marbling or firmness was observed in pigs fed either of the DDGS diets compared with pigs fed the control diet.

Pigs fed the diets containing DDGS did not have elevated concentrations of sulphur in their organs compared with pigs fed the control diet. Instead, Professor Stein said excess sulphur was excreted in the urine.

Thus, excess dietary sulphur does not accumulate in tissues from pigs, as is the case for some other minerals, because pigs appear to be able to regulate sulphur in the body by increasing or reducing urinary excretion in response to changes in sulphur intake.

Professor Stein said that the results of this research should give producers more confidence about incorporating DDGS into swine diets.

"What these results tell us is that even DDGS with a high sulphur content can be fed at up to a 30 per cent inclusion rate without negative effects because pigs have the ability to regulate sulphur retention and excretion," he said.