Effect of whole seaweed and seaweed extract on rumen fermentation, nutrient digestibility, and methane emissions of beef heifers fed a high-forage diet

Abstract

The effect of the whole seaweed Ascophyllum nodosum and a seaweed extract generated from Himanthalia elongata on rumen fermentation, nutrient digestibility, and methane (CH4 ) emissions of beef heifers fed a high-forage diet was assessed. A replicated 3 × 3 Latin square was conducted using six ruminally cannulated beef heifers fed a basal diet consisting of 52% barley silage, 44% barley straw, and 4% mineral supplement (dry matter (DM) basis). Whole A. nodosum and H. elongata extract were supplemented into the diet at 2% of dietary DM replacing equal proportions of barley silage and barley straw. There was no effect of treatment (p > 0.05) on the production of ammonia (NH3 ), protozoa counts, total volatile fatty acids, or ruminal pH. The apparent total tract digestibility of neutral detergent fibre (NDF) and acid detergent fibre (ADF) was increased (p < 0.05) by the H. elongata extract compared to the control, but there was no effect (p > 0.05) of A. nodosum or H. elongata extract on CH4 production (g/day) or yield (g/kg DM intake). In conclusion, neither the whole A. nodosum nor the H. elongata extract demonstrated anti-methanogenic activity in a high-forage diet.