University of Illinois research indicates the nutritional value of whey co-products – whey powder, whey permeate, low-ash whey permeate – can be utilized in weanling pigs diets when formulated on the basis of metabolizable energy and the standardized total tract digestibility of phosphorus.

The new research shows the whey co-products can serve as a lactose source for pigs, explains Illinois swine nutritionist Hans Stein. "We wanted to determine the energy concentration and digestibility of phosphorus in whey powder, in conventional whey permeate, and in low-ash whey permeate because these values had not been determined," Stein explains.

Skim milk powder can be used to meet the weanling pigs’ requirement for lactose, but it is costly and often uneconomical. Whey powder, a co-product of the cheese industry, contains lactose and protein and is less costly, he adds.

Some cheesemakers remove protein from whey powder for use in human foods. "When they take the protein out, they are left with whey permeate, which contains mainly lactose and ash,” he says.

The Illinois researchers used conventional whey powder – 66% lactose, 13.2% crude protein, 15.8% ash – and two permeate products. One was a conventional whey permeate that contains approximately 76% lactose and 9% ash. Most of the ash had been removed from the other permeate product, which was approximately 89% lactose and only 1.7% ash.

The concentration of metabolizable energy and the standardized total tract digestibility of phosphorus were determined in the three ingredients using weanling pigs.

Results showed the conventional whey permeate contains less metabolizable energy than whey powder (3,081 vs. 3,462 kcal/kg DM [dry matter]). But the low-ash whey permeate contained 3,593 kcal metabolizable energy/kg DM.

Removing protein from the whey powder lowered metabolizable energy in the whey permeate. “If ash is also removed, the resulting high-lactose, low-ash whey permeate has a concentration of metabolizable energy that is slightly greater than that in whey powder,” Stein explains.

The concentration of phosphorus in whey powder, conventional whey permeate and low-ash whey permeate was 0.63, 0.57 and 0.10%, respectively, but the standardized total tract digestibility of phosphorus was not different among the three ingredients (91.2, 93.1, and 91.8%, respectively).

“These data clearly indicate that phosphorus from all three ingredients is well digested by weanling pigs,” he says, which makes it a viable ingredient for young pig diets.

The study, published in a recent issue of the Journal of Animal Science, was co-authored by Jung Wook Lee, University of Illinois, Beob Kim, Konkuk University, Seoul, South Korea and Stein.