Objective
1. To evaluate alkaline (calcium hydroxide) treatment of canola seed [whole seed control, green seed (Canada Grade 3), or heated seed (Canada Grade 3)] on ruminal degradability as a strategy to create rumen protected lipid.
2. Evaluate the dose (3, 4, 5, or 6% of dry matter intake) of alkaline-treated canola seed for high producing dairy cattle.
3. Evaluate cost effectiveness of using calcium hydroxide-treated canola seed.
Project Description
Canadians value milk and milk products consuming, on average, nearly 65 L of fluid milk, 22 kg of cheese, 10 L of cream, nearly 10 L of yogurt, and over 6.5 kg of butter per person annually. In addition, the value of milk is based on milk components and quota is regulated based on the amount of fat shipped. As such, producers are highly motivated to produce milk with high component concentrations to maximize revenue, manage production, and minimize transportation costs. Adding palmitic acid has been an effective strategy to increase milk fat yield. However, there have been numerous concerns associated with the use of palmitic acid including concerns over the hardness of butter, markedly increasing cost, and concerns over the sustainability of palm harvest and oil extraction. With tight margins for dairy producers, identifying local and renewable feed ingredients that stimulate milk fat and potentially milk protein yield could help improve profitability. While canola is a high value crop used primarily for oil extraction, canola with too many green seeds or heated seeds results in downgrading and reduction of value. In addition, canola exports from Canada have been targeted recently as countries have imposed tariffs thereby affecting the value for canola producers. Strategies that help build alternative markets may help improve options for canola growers. From a nutritional standpoint, whole canola seed has high crude protein (20%) and greater than 40% lipid. In addition, canola has a recalcitrant seed coat preventing ruminal degradation of the protected inner components unless the seed coat is damaged. Feeding canola meal has been reported to improve the supply of essential amino acids in the plasma of dairy cattle helping to support the greater milk production often observed when canola meal partially replaces other protein sources. Feeding whole canola seed has been evaluated with cows fed ground canola seed consuming a similar amount of feed and producing a similar amount of milk; however, milk fat concentration was reduced as could be expected given the high concentrations of ruminally-available unsaturated fatty acids. Even strategies utilizing mechanically extracted canola meal can result in lower dry matter intake and potentially milk yield. Strategies to reduce the ruminal availability of nutrients within canola seed while increasing post-ruminal supply have also been evaluated including micronization, a proprietary protection method that heats proteins and fats to prevent rapid degradation in the rumen, or through alkaline treatment. Of those methods, alkaline treatment (calcium hydroxide) has greatest likelihood for on-farm adoption as it requires the least infrastructure and lowest energy consumption. Past research evaluating alkaline treatment of whole canola seed has shown that alkaline treatment of canola seed without any additional processing increased the flow of unsaturated fatty acids to the duodenum relative to ground canola indicating that alkaline treatment provided protection of the fatty acids from ruminal modification. The treatment process in that study included exposing whole canola seeds to calcium hydroxide followed by treatment with hydrogen peroxide. Alkaline treatment damages the seed coat and the high pH and abundant calcium allows for the formation of calcium salts (fatty acids covalently bound to Ca) which have relatively low ruminal availability. In a follow-up study, the same authors fed crushed, alkaline treated whole canola, a diet with calcium-salts of fatty acids, or a no added fat control. In that study, authors used diets that were very high in fatty acids (>8%) which is well beyond that recommended. As could be expected, cows fed the supplemental fatty acids tended to eat less dry matter, but milk yield and fat percentage did not differ. When comparing the ground and alkaline treated canola, cows fed alkaline treated canola had similar milk yield but greater milk fat percentage. Canola feeding also resulted in a greater proportion of unsaturated fatty acids helping to improve the concentration of desirable fatty acids in milk. Some studies provide compelling support that alkaline treatment of whole canola may be a means to produce a low-cost rumen protected fatty acid supplement for dairy cows with methodology that is simple enough to apply on farm. However, research is needed to confirm whether responses occur when feeding green or heat damaged canola and to confirm milk fat and milk protein yields with diets reflective of current formulation strategies used in Western Canada.
