The effects of feeding an algae supplement on milk yield, milk components, and dry matter intake

Abstract Text: Feeding docosahexaenoic acid (DHA) via algae supplementation could increase milk polyunsaturated fats.  The objective of this study, conducted at the University of Kentucky Coldstream Dairy, was to determine the effects of feeding cows Schizochytrium sp. Microalgae (SP-1™, Alltech, Inc., Nicholasville, KY) on milk fat and DHA content, dry matter intake, and milk yield.  Eight multiparous, mid-lactation, Holstein cows were housed in a tie-stall barn and fed a basal ration 2X.  Cows were blocked by milk production and DIM and assigned to 1 of 4 treatments: 0, 100, 300, or 600 g of algae per day for 28 days.  Milk samples were composited by week and analyzed for fat and DHA composition.  Dry matter intake and milk yield were recorded daily and averaged by week. The MIXED procedure of SAS (SAS Institute, Inc., Cary, NC) was used to evaluate fixed effects of week, treatment, and their interactions on milk fat percentage and DHA content (g/d), milk yield (kg/d), and DMI (kg/d), with block within treatment as subject repeated by week.  Stepwise backward elimination was used to remove non-significant interactions (P ≥ 0.05).  All main effects were kept in each model regardless of significance level.  Week affected milk yield (P < 0.01) but treatment did not (P = 0.30). Milk yield (mean ± SE) for periods 1 to 4 was 30.44, 29.10, 25.10, and 25.21 ± 4.58 kg, respectively.  Treatment and week affected fat percentage (P = 0.02).  Fat percentage was greater (P < 0.05) for cows on treatments 0 and 100 (4.20 and 3.54 ± 0.18%, respectively) than cows on treatments 300 and 600 (2.52 and 2.52 ± 0.18 %, respectively).  Treatment, week, and the interaction of treatment × week affected DMI (P < 0.01, P < 0.01, and P = 0.02, respectively).  Dry matter intake decreased across time across treatments until week 4.  Treatment and the interaction of treatment × week affected milk DHA (P = 0.03 and P = 0.02, respectively).  DHA content in milk was greater (P< 0.05) for cows on treatment 300 and 600 (3.30 and 5.18 ± 0.66 g/d, respectively) than cows on treatment 0 and 100 (0.00 and 0.39 ± 0.66 g/d, respectively).  This data suggests supplementing lactating dairy cows with high-DHA microalgae may allow for the incorporation of polyunsaturated fats, including DHA, into milk; however, decreases in milk fat percentage and DMI may limit on-farm application.

Keywords: algae, milk fat, DHA