What canola by-products are beneficial for grower pigs?

The type of canola is used, and how the oil is extracted alter the nutritional offering of by-products used in swine feed, say researchers. 

An international group of researchers, from universities in both Brazil and Canada, evaluated the use of different types of canola by-products as feed ingredients in the diets of grower pigs.

The research team published their results in the journal of Animal Feed Science and Technology​.​​

“The objectives of the present study were to determine and compare the digestible energy (DE) and calculated net energy (NE) values and coefficient of standardized ileal digestibility (CSID) of amino acids (AA) for [Brassica] B. napus canola meal, with those of B. juncea canola meal, B. napus canola expeller and B. napus canola press-cake fed to growing pigs; and to establish interrelationships between chemical composition and energy and nutrient digestibility for canola co-products,”​ said the authors.

The group found that amino acid digestibility was not consistent among the different types of canola co-products evaluated and that not all forms of processing resulted in the same nutritional outcome.

“B. juncea canola meal had greater CSID of AA and calculated NE value than B. napus canola meal, indicating that B. juncea canola meal can contribute more dietary digestible AA and energy to the pig than B. napus canola meal,” ​said the team. 

They added: “Differences in CATTD [coefficient of apparent total tract digestibility] of GE [gross energy], NE value and CSID of AA data among B. napus canola co-products indicate that method of oil extraction from canola seed can affect energy and AA availability in the resulting canola co-products."​

By-product use​

Increasing demand for cereal grains and oilseeds has put economic pressure on ingredients used for swine feed, said the researchers. But co-products from food and biofuel industries should be examined for use as replacement feed ingredients.

Canola is an oilseed crop grown for use in the food and biofuel sectors, they said. Several strains of the plant are produced, and different oil extraction methods are used including expeller pressing, cold pressing or solvent extraction after pressing.

Solvent extraction is the most common and leaves a canola meal that is less than 30g oil/kg, they said. Cold pressing, without using solvent extraction, leaves a co-product with more than 100g oil/kg while expeller pressing leaves less oil than cold pressing.

Nutritional values for B. napus canola meal and its use in pig diets are known, said the researchers. But they stressed that information on the nutritional value, in vivo energy, nutrient digestibility and chemical composition of B. juncea meal and both B. napus expeller and press-cake is lacking.

Study details​

In the project, five ileal-cannulated barrows were given one of five diets for a period of nine days, said the researchers.  

The diets had an indigestible marker, were maize starch-based and included a control and the basal diet with B. juncea canola meal, B. napus canola meal, B. napus expeller or B. napus press-cake as the sole source of protein.

Feed ingredient and diets were analyzed for acid detergent fiber (ADF), inclusive residual ash, calcium, phosphorus (P) and starch, they said. Ingredients, feeds and ileal digesta were checked for AA and all samples, including feces, were tested for dry matter (DM) and crude protein (CP).

Gross energy (GE) was determined for feeds, ingredients, digesta and fecal matter, they said. And the coefficient of apparent ileal digestibility (CAID) and CATTD was established for the feeds, along with the CSID of amino acids.

The coefficient of apparent hindgut fermentation (CAHD) of GE also was calculated, they said.

Results​

Pigs stayed healthy and did not refuse any of the diets, said the researchers. On a fed basis, B. napus meal was similar in CP and AA to B. napus expeller, but B. napus expeller had more CP, AA, NDF and ADF and less EE than the press-cake.

“B. juncea canola meal can contribute via small intestinal digestion more dietary digestible AA and energy to the pig than B. napus canola meal,” ​they said. “Differences in CAID of GE, calculated NE value and CSID of AA data among B. napus canola co-products indicate that method of oil extraction from canola seed affects energy and AA availability in canola co-products.”​

B. juncea canola meal can offer more dietary AA and energy in pig diets than B. napus canola meal, concluded the authors. The CSID of lysine, CATTD, CAHD and CAID of GE and NE values were larger for B. juncea canola meal than for the other meal.

The CSID of lysine and CATTD of GE for B. napus meal and press-cake were similar, but were both lower than what was found in the B. napus canola expeller, they said. The press-cake had a greater calculated NE value than the expeller.