US - USDA Agricultural Research Service (ARS) scientists in Wisconsin are helping dairy farmers weigh the merits of protein supplements available for their cattle.
When it comes to protein supplements, dairy producers have two options: soybean meal and canola meal.
Canola meal is a relatively new option - production increased rapidly in the 1990s as a cold-tolerant crop, but it was initially raised primarily for its seed oil.
"Canola only recently caught on as a protein source for cattle when new varieties were developed," said Glen A. Broderick, a former ARS dairy scientist with the US Dairy Forage Research Center in Madison, Wisconsin.
Mr Broderick (now retired) and his colleagues divided 50 lactating dairy cows into 5 groups and varied their diets (high and low amounts of soybean meal, high and low amounts of canola meal, and a mix of low canola and low soybean meal).
Each group received a different diet every three weeks, and researchers measured the amount of milk, milk proteins and urine nitrogen produced by the cows while on each diet.
The diets were balanced to provide adequate levels of protein and included standard corn and alfalfa silages, corn grain and the usual supplementary vitamins, minerals and normal levels of neutral detergent fibre.
After 15 weeks, researchers found that the canola meal supplement resulted in more milk and milk protein production per day than soybean meal. The effects were about the same in both the high- and low-protein diets.
Specifically, cows fed canola meal produced an average 88.8 pounds of milk per day, compared with 86.6 pounds produced by cows on soybean meal, a 3-per cent difference per cow. Cows on canola meal also showed a similar increase in production of milk protein.
Many dairy producers have hundreds of cows, so every increase in yield per cow translates into a more financially viable dairy operation.
Per unit of protein, canola meal now costs about the same as soybean meal, but the findings could save costs in the long run by giving dairy producers a new option in the face of ever-changing prices, Mr Broderick said.
The study was partially funded by the Canola Council of Canada.
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