Finding the Ideal Combination

Peas for animal feed

by Kim Waalderbos

Low grade peas or pea screenings still have high starch content after processing, and may be a good energy and protein source in livestock feeds. However, these co-products also have some shortcomings to address.

Researchers at the University of Saskatchewan have been exploring how to balance these shortcomings by blending low-value pea screenings with biofuel co-products to determine if it is possible to make high-value pellets for animal feeds. 

“Pea screenings can have lots of nutrients, and on the Prairies we have lots of pea screenings,” says Peiqiang Yu, a Department of Animal and Poultry Science Professor and Ministry of Agriculture Strategic Research Chair. “We have been developing different pelleted products with peas to find which
combinations work best and provide the best nutrient profiles for ruminants.”

Yu says peas have two key shortcomings. First, they degrade very quickly in the rumen, which limits nutrient availability, can lead to protein loss, and may cause digestive disorders in ruminants such as beef and dairy cattle. Second, peas have a unique amino acid profile. “They are high in lysine and tryptophan, but deficient in sulphur-containing amino acids: methionine and cystine,” Yu explains.

Yu and team recognized that these two shortcomings must be addressed for peas to be used efficiently in livestock feeds. To balance the amino acid profile, the research team looked to the oilseeds: canola and carinata. Oilseeds have the opposite amino acid profile of peas, Yu says. “If we combine peas with these oilseeds, we hypothesized we could balance the amino acids.”

Additionally, carinata meal is a relatively new offering from the biofuel sector and, to date, has not been fully understood or registered for all species with the Canadian Food Inspection Agency (just as beef cattle feed). So, the team was keen to explore its potential in livestock feeds. 

To address the rate that peas degrade in the rumen, the researchers looked to a feed additive called lignosulfonate. This is a byproduct of the wood industry and has been effectively used with soybeans to slow down the rumen degradation, thus increasing bypass protein. It can also increase pellet
durability, Yu says. The researchers hoped it might have similar benefits if used with peas. 

For this study, Yu and his team developed eight different combinations of these ingredients into feed pellets (see chart on next page). Pea screenings were included at either low (20 to 25 per cent of the pellet) or high (45 to 50 per cent of the pellet) levels. If used, lignosulfonate was included up to five per cent.

Through several different experiments, the pellet types were evaluated for the quality of the pellet durability as well as nutritive values including: chemical composition, condensed tannins, glucosinolates, amino acids, protein and carbohydrates fractions, and various measures of energy and protein
for beef and dairy cattle.

The results showed the research team could overcome the two key shortcomings of using peas as livestock feed. “We showed we can blend these feed ingredients effectively to optimize the nutrients available to ruminants,” Yu says. The team found using the feed additive lignosulfonate successfully reduced the degradation of crude protein in the rumen. They also found blending peas with canola or carinata can successfully increase amino acids and nutrient availability.

In all the blended pellet products tested, glucosinolate and condensed tannin levels were low. “This means they do not cause any risk to the health of ruminants,” Yu explains.

Ultimately, the most durable pellet was found to be the products containing higher carinata meal and lower pea screenings (BPP3 and BPP4). These two pellet products also were found to have the highest total amino acids on a dry matter basis, the highest bypass protein, total metabolizable protein, and truly absorbed protein supply, as well as the highest net energy (lactation) and feed milk values. 

“Based on these studies, these two particular carinata-based pellet products, BPP3 and BPP4, can be used as a potentially highvalue concentrate feed for cattle,” Yu says.