Incremental amounts of ground flaxseed decrease milk yield but increase n-3 fatty acids and conjugated linoleic acids...

Area of Science:

• Animal Science
• Dairy Nutrition
• Ruminant Metabolism

Background:

• Dietary fat supplementation influences milk composition and production in dairy cows.
• Flaxseed is a source of omega-3 fatty acids and can alter rumen fermentation.

Purpose of the Study:

• To evaluate the impact of increasing ground flaxseed (GFX) levels on milk yield, component yields, fatty acid profile, ruminal metabolism, and nutrient digestibility in dairy cows on high-forage diets.

Main Methods:

• A replicated 4x4 Latin square design with 20 Jersey cows (12 multiparous, 8 primiparous).
• Diets consisted of a 63:37 forage-to-concentrate ratio, with GFX replacing concentrate at 0, 5, 10, or 15% of dry matter.
• Measurements included milk yield, component analysis, fatty acid profiling, ruminal volatile fatty acids, and nutrient digestibility.

Main Results:

• Milk yield and dry matter intake decreased linearly with increasing GFX. Milk protein and fat yields also decreased linearly.
• Ruminal acetate and butyrate proportions decreased, while propionate increased, reducing the acetate-to-propionate ratio.
• Milk concentrations of odd- and branched-chain fatty acids and saturated fatty acids decreased, while beneficial n-3 fatty acids (e.g., cis-9,trans-11 18:2, alpha-linolenic acid) and total n-3 FA increased.

Conclusions:

• Ground flaxseed supplementation linearly reduces milk yield and nutrient digestibility in dairy cows fed high-forage diets.
• GFX inclusion significantly alters milk fatty acid profiles, increasing desirable n-3 fatty acids and decreasing saturated fatty acids.
• While milk production is reduced, GFX shows potential for modulating milk fat composition towards healthier profiles.