Earlier this month we reported on a study which found that canola meal can be included in the diets of weaned pigs at levels of up to 25% without a detrimental effect on growth. Now, researchers from Agriculture and Agri-Food Canada in Sherbrooke, Quebec, have carried out a meta-analysis of data on the inclusion of canola meal in the diets of dairy cows, and concluded that milk production and milk protein yield responded positively to substitution of protein ingredients with canola meal.
“This research showed that substitution of proteins with canola meal resulted in 0.75kg more milk and 29g more milk protein per cow per day,” Brittany Dyck, canola meal manager for the Canola Council of Canada, told FeedNavigator.
She said the meta-analysis results indicated improvements in milk yield at canola meal inclusion levels as low as 1kg per day.
Mechanism still a mystery
The mechanism behind these results is not fully understood, but it is thought to be linked to RUP (rumen undegradable protein) levels – the research indicated that canola meal provided the cows with higher levels of rumen bypass protein than is reported in literature.
“We know that the RUP values, regardless of method of determination, are higher than most models predict,” said Dyck.
She said this had been confirmed by new research, which had shown that the amount of protein escaping degradation in the rumen and being available for digestion in the intestine was higher than previously reported.
Amino acids in balance
It is also thought that the balance of amino acids - as opposed to the presence and levels of individual amino acids - plays a key role.
“Although production with a canola diet was slightly better than with soybean meal, this did not appear to be due to methionine or lysine – adding these amino acids made no difference. Nor was it due to phenylalanine – increasing that amino acid did not produce the response expected,” said Dyck.
She added that the amino acid profile of wheat DDGS (dried distillers grain with solubles) is better than that of corn DDGS, and, that the results obtained with wheat DDGS were closer to those obtained with canola meal.
“Canola meal has a great amino acid profile very complimentary to the amino acid profile of milk, otherwise known as protein score. Canola meal’s protein score is second only to fish meal,” she said.
The Canola Council of Canada is currently in the process of developing better profiles for canola meal, so that users can predict the animal’s response to a meal more accurately.
“Right now, both the energy and RUP values seem to be underestimated in ration balancing programmes,” said Dyck
The industry association is also hoping the new profiles will provide “some additional clues” to the “elusive mechanism behind the higher milk and milk protein yield”.