Muizelaar1,2*, S. K. Kar1, G. van Duinkerken1, J. Dijkstra2
1Wageningen Livestock Research, Wageningen University & Research, PO Box 338, 6700 AH Wageningen, the Netherlands
2Animal Nutrition Group, Wageningen University & Research, PO Box 338, 6700 AH Wageningen, the Netherlands
Research on supplementing ruminant diets with seaweeds has mainly focused on the use of Ascophyllum nodosum (Phaeophyta) and Asparagopsis taxiformis (Rhodophyta). In the current study, supplementation of diets of lactating dairy cows with three algae commonly found in northwestern Europe was evaluated for its effects on lactational performance, enteric gas production and rumen microbiota composition. 64 Dairy cows (91 ± 22.6 days in milk; 35.4 ± 8.13 kg/day fat- and protein-corrected milk; mean ± standard deviation) were randomly assigned to one of four treatments. A basal diet (54% grass silage, 21% corn silage, 25% concentrate; DM basis) was not supplemented (control) or supplemented with either 150 g/day (fresh weight of dried seaweed) of Chondrus crispus (Rhodophyta), Saccharina latissima (Phaeophyta) or a 50/50 mixture (DM basis) of S. latissima and Fucus serratus (Phaeophyta). To investigate short- and long-term effects of seaweed on the rumen microbiota, 8 cows per treatment were randomly selected and rumen fluid (performed 16S rRNA amplicon sequencing) was obtained via oral stomach tube technique at five different time points (-3, 2, 35, 60 and 81 d after first day of feeding seaweed). Milk yield (29.5 vs 28.3 kg/d, respectively) and milk lactose content (4.59 vs 4.53%, respectively) increased at S. latissima compared to the control. Other milk or efficiency related parameters did not differ between the control and the seaweed treatments. Gas emissions (CH4, CO2 and H2) were not affected by the seaweed treatments. Microbiota composition results are currently being evaluated and will be presented at the congress.