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US/Chinese study wheat bran digestibility in pigs

Research conducted by US and Chinese researchers is helping to determine the nutritional value of wheat bran in diets fed to pigs. More inclusion of wheat bran meant less energy available for pigs.

A news update by the University of Illinois explained about the research, written by scientists from the University of Illinois, USA and the China Agricultural University in Beijing, China. It was recently published in the Journal of Animal Science.

Wheat bran, like many other co-products from the human food industries, contains more fibre than corn and soybean meal, which adversely affects energy digestibility

Co-products for pigs

“To save on feed costs, more producers are turning to co-products,” explained Dr Hans H. Stein, professor of animal sciences at the University of Illinois. “Therefore, there is a need to determine the energy contribution from fibre-rich ingredients. But the effect of dietary fibre on heat production and net energy of diets is unclear.”

The research was conducted in the calorimetry unit at China Agricultural University. Growing barrows were fed diets containing 0, 15, or 30% wheat bran. The pigs were housed in metabolism crates inside calorimetry chambers built to measure gas exchange and heat production.

Photo: Koos Groenewold
Photo: Koos Groenewold

More wheat bran, less energy

The digestible energy (DE), metabolisable energy (ME), and net energy (NE) in the diets declined as more wheat bran was included. The DE content of diets containing no wheat bran was 3,454 kcal/kg, compared with 3,161 kcal/kg in diets containing 30% wheat bran. The ME content of the diets decreased from 3,400 to 3,091 kcal/kg, and NE content decreased from 1,808 to 1,458 kcal/kg.

The research also validated a procedure commonly used to determine NE. Using the difference procedure, Stein’s team determined the DE, ME, and NE of wheat bran to be 2,168, 2,117, and 896 kcal/kg, respectively. These values were similar to those derived using a regression procedure.

Accurate digestibility values

Stein says that DE and ME are usually determined using the difference procedure, but NE is usually determined using regression equations. As far as he knows, nobody has compared values derived from the difference procedure with values derived via regression.

“Since experiments to determine NE via the difference procedure are more difficult to conduct than determining DE and ME, it’s helpful to know that using regression to determine NE will yield an accurate value,” Stein concluded.

The paper, ‘Wheat bran reduces concentrations of digestible, metabolizable, and net energy in diets fed to pigs, but energy values in wheat bran determined by the difference procedure are not different from values estimated from a linear regression procedure’, was published in the July 2016 issue of the Journal of Animal Science. It was co-authored by Neil Jaworski of the University of Illinois, and Dewen Liu and Defa Li of China Agricultural University in Beijing.

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