Project Decsription
There is widespread interest in the inclusion of flax seed in human and animal diets for health and performance benefits. Flax seed requires some form of processing for efficient nutritional utilization. Whole seed may not be fully digested and milled products may not be stable for a sufficient period due to oxidation of the high unsaturated fatty acid content. A number of companies produce extruded products. These companies include O & T Farms, Regina, SK, a company well positioned to make use of Saskatchewan produced flax seed.
Rations high in fat content are known to affect ration nutrient digestibility. In 1917 Givens (JBC 31:441) reported a reduction in calcium balance in dogs when fat was fed and Whitehead (Br Py Sci.12:249. 1971) reported reduced calcium, iron, magnesium and zinc retention when fat was added to broiler chick diets. In cattle, there may be a reduction in fiber digestibility and formation of soaps with fatty acids and divalent cations that may be poorly absorbed. Pantoja (1994) summarized literature documenting this effect of added fat decreasing NDF fermentation and digestibility. The effect of long chain unsaturated fatty acids on NDF digestibility was greater than for saturated fatty acids.
The objective of this research was to determine the effect of two extruded flax seed products produced by O&T Farms in comparison to a calcium salt fatty acid product and a control ration with no added lipid. The trial was conducted with high production dairy cows in the Rayner dairy herd to measure milk yield and composition, total tract apparent digestibility of major nutrients including minerals, and the effect on milk fatty acid content.
This project demonstrated that the inclusion of the extruded flax seed and pea product (LinPRO-R) and the calcium salt fat product (Megalac-R) did not reduce major nutrient or mineral apparent digestibility. The extruded product containing faba beans did reduce digestibility of NDF, cell wall bound protein (NDIN), magnesium, and manganese and tended to reduce calcium and fat digestibility. These findings are in contrast to the observed reduction in mineral digestibility associated with increased dietary fat in poultry, dogs, rats and humans. These rations contained a variety of ingredients. The lack of fat effect may be related to the high acid hydrolysis fat level in the control ration. Another factor may be the low intestinal pH of ruminants that allows dissociation of fatty acid salts. If the ether extract method had been used the control fat level would have been expected to be not more than 3% of dry matter. Further research is needed to identify the effect of non-triglyceride fatty acids on mineral apparent digestibility. The effect of the fat supplements on milk fatty acids was as expected. Saturated fatty acids were reduced while alpha-linolenic and total omega-3 fatty acids were increased. The high fecal DHA level requires further investigation. Previous work (Moats, MSc) has shown faba beans to be a satisfactory ingredient in an extruded flax product and the effects in this trial may have been due to the nature of the individual batch of faba beans used.
Grower Benefits
- The addition of fat in the form of extruded flax or calcium salts of fatty acids did not reduce major nutrient or mineral apparent digestibility in lactating cow rations.
- The digestibility of calcium, phosphorus and magnesium were close to the average reported in NRC Dairy requirement publications.
- Digestibility for some nutrients was lower for the extruded product that contained faba beans in place of peas.
- NDF digestibility was not depressed by added fat.
- Milk fat omega-3 fatty acids were significantly increased by both extruded flax products.
- Fecal fatty acid composition has not been widely reported in research literature. In this trial ration, did not change fatty acid content, however, feces from all four rations contained substantial levels of DHA (C22:6n3) and ALA (C18:3n3).
