Study shows benefit of alternative feed ingredient for use in swine diets

The co-product flaxseed meal may offer an alternative energy and protein ingredient for use in the diets of growing pigs, say researchers. Photo by: iStock

A team of researchers from the University of Manitoba, the University of Guelph and DuPont Industrial Biosciences examined the use and nutritive value of flaxseed meal (FM) when included in swine diets. The group published its work in the journal of Animal Feed Science and Technology​​​.

“Characterization of the nutritive value of FM as an alternative to conventional ingredients opens the way for optimizing its use in pig diets,”​ the researchers said. “Thus, the objective of this study was to determine the digestibility of [amino acids] AA, digestible energy (DE), metabolizable (ME) and calculated net energy (NE) values of FM when fed to growing pigs.”​

The group found that flaxseed could provide an alternative protein, amino acid and energy ingredient in swine feed for growing pigs, the researchers said. “The use of FM is limited by its low lysine content as well as its dietary fiber content and the bulking capacity,”​ they added.

“The opportunity of incorporating FM in combination with other oilseed meals and exogenous enzymes during feed formulation for swine should be explored,” ​they said. “More work is needed to determine the net energy content of FM using more accurate methods such as indirect calorimetry.”​

The project was partially funded by DuPont Industrial Biosciences.

1/ Why flaxseed meal?​

Common energy and protein ingredient in feed, like corn and soybean meal, have increased in price over time, said the researchers. Alternative feed ingredients that can be used in swine diets are needed.

Flax is a common food crop used to generate vegetable oil, they said. However, the crushing process generates flaxseed meal (FM).

The co-product is high in alpha-linoleic acid, oil, protein and dietary fiber, they said. It has gained some attention both as a potential ingredient to add energy and amino acids to swine feed and as a functional ingredient to provide omega-3 enriched pork and improve gut health.

The AA and phosphorus (P) digestibility of FM has only been partially examined and there is a lack of information on the energy content of FM for growing pigs fed a corn- and soybean-based diet and in regards to the standardized ileal digestibility (SID) of some dispensable amino acids.

“If included beyond optimum level in pig diets, the dietary fiber and glucosinolates content of FM may depress feed intake and reduce nutrient utilization,”​ said the researchers. Additional information on nutritional elements is needed to improve the use of the alternative feed ingredient, they added.

2/ Methods and materials​

In the feeding trial nine cannulated barrows were given one of three experimental diets for a period of 11 days, the researchers said. Pigs were rotated between each of the diets for a total feeding trial duration of 33 days.

The diets included a basal diet made with corn and soybean meal (Basal), a corn-soybean meal-based diet that replaced a portion of those ingredients with 278g/kg FM (Basal-FM) and a low nitrogen (N)-casein and corn starch-diet (LND), they said. Titanium dioxide was used in all diets as an indigestible marker.

“The basal and Basal-FM diets were formulated to have similar ratios of common ingredients supplying energy, AA, and P,”​ they said. “The basal diet was used to determine the digestible nutrient content by the difference method according to Adeola (2001), whilst the LND was used to estimate the basal endogenous N and AA losses to determine the SID of N and AA.”​

Pigs were weighed at the start of each experimental feeding period, given a period of acclimation to the new diet and fecal, urine and ileal digesta were sampled, said the researchers.

The coefficient of apparent ileal digestibility (CAID) and coefficient of standardized ileal digestibility (CSID) of amino acids were calculated along with the crude protein (CP), digestible energy (DE) and metabolizable energy (ME) values of FM, they said. The net energy (NE) value of FM also was established.

3/ Results ​

Overall researchers found that pigs were healthy throughout the feeding trial and there were no palatability issues with the feeds, the researchers said.

“FM is an attractive alternative source of dietary AA and energy that can be incorporated in swine diets to replace common protein sources,”​ the researchers said. Using the CSID of amino acids and the determined NE values found, flaxseed meal is an ingredient able to provide protein and energy in the diets of growing pigs, they added.

The CSID and CAID of CP found in flaxseed meal were 0.694 and 0.599, respectively, they said. The CAID and CSID for AA ranged from 0.509 to 0.755 and 0.580-0.791.

“The CATTD [coefficient of apparent total tract digestibility] of GE [gross energy] in FM was 0.76,” ​they said. “The DE, ME and calculated NE values for FM were 12.6, 11.4 and 7.5 MJ/kg, respectively.”​

The most abundant indispensable AA in the feed ingredient were arginine, leucine, phenylalanine and valine, and the most digestible were arginine, isoleucine and phenylalanine, said the researchers. The least abundant AA were histidine, methionine and tryptophan and the less digestible amino acids were lysine and histidine.

Source: Animal Feed Science and Technology​

Authors: S. Ndou, E. Kiarie, M. Walsh, C. Nyachoti