Objectives
The major objective of this research was to investigate the effects of feeding ground flaxseed, defatted flaxseed meal and organic flaxseed meal on feed intake, milk production and composition, and milk fatty acid profile in dairy cows.
Project Description
This study aimed to determine the effects of feeding ground whole flaxseed and two types of mechanically extracted flaxseed meals on dry matter (DM) intake (DMI), milk production and composition, ruminal fermentation characteristics, total-tract nutrient digestibility and N balance in dairy cows. Twelve multiparous Holstein cows [122 ± 20 days in milk at the start of the study] were used in a replicated 4 × 4 Latin square design with 4 dietary treatments. One square had 4 ruminally cannulated cows that were used to determine dietary effects on ruminal fermentation characteristics and total tract nutrient digestibility. The 4 dietary treatments tested were a barley silage-based diet with canola meal (CM; 21.1% of diet DM) as the main protein source (designated CON), and diets containing ground whole flaxseed (designated GWF; 4.92% of diet DM), defatted flaxseed meal (designated DFM; 19.7% of diet DM), or organic flaxseed meal (designated OFM; 20.2% of diet DM) as partial replacements for CM. Experimental diets were balanced for crude fat content (3.66%; DM basis). Experimental periods consisted of 18 d of dietary adaptation and 10 d of data and sample collection. Orthogonal contrasts were used to test for the following treatment differences: CON vs. GWF; CON vs. [DFM + OFM]; and GWF vs. [DFM + OFM]. Cows fed GWF or flaxseed meals (i.e., DFM and OFM) exhibited greater DMI compared to cows fed the CON control diet; however, milk yield tended to be greater in cows fed the CON diet compared to those fed the flaxseed meals. Milk protein content was improved and milk urea-nitrogen concentration reduced in cows fed flaxseed meals compared to those fed the CON diet, whereas milk fat content and yield were unchanged. Ruminal fermentation profiles were unaffected by diet. Fecal nitrogen excretion was greater for cows fed the CON diet compared to those fed GWF and flaxseed meals and, therefore, total-tract crude protein digestibility was reduced in cows fed the CON diet compared to those fed GWF and flaxseed meals. Feeding GWF and flaxseed meals increased the milk concentrations of omega-3 fatty acids (C18:3n-3) in milk while reducing total saturated fatty acids compared with the control diet. In conclusion, replacing CM with GWF or flaxseed meals increased feed intake and improved milk protein content and nitrogen utilization, while enhancing the omega-3 content of milk. These benefits were achieved without negative impacts on rumen fermentation or overall nitrogen balance. However, a tendency for reduced milk yield was observed with flaxseed supplementation, suggesting a balance between improving milk nutritional quality and maintaining production efficiency.
Grower Benefits
It can be summarized that feeding ground whole flaxseed (4.92% of DM), defatted flaxseed meal (19.7% of DM) and organic flaxseed meal (20.2% of DM) as a partial replacement for canola meal can use as a dietary strategy for increase bovine milk fat content of omega-3 PUFA including ALA while maintaining the rumen fermentation, ruminal digestibility of nutrients, N balance and microbial protein production. Contrary to expectations based on increased DMI, supplementation with ground flaxseed and mechanically separated flaxseed meals showed a tendency to negatively impact milk yield.
