Feeding a marine-based rumen buffer increases milk production and decreases time of low reticulo-rumen pH in grazing dairy cows offered perennial ryegrass-based pasture

Abstract

Dairy cows grazing highly digestible perennial ryegrass-based pastures are reportedly susceptible to low rumen pH. This experiment investigates the effect of feeding a novel marine-based rumen buffering product on milk production, milk composition and reticulo-rumen pH in dairy cows grazing perennial ryegrass-based pasture supplemented with concentrates. Three primiparous and twenty-one multiparous spring calving dairy cows (58 ± 12.6 days in milk) were blocked by parity (3.2 ± 1.56) and pre-experimental milk yield (36.0 ± 6.55 kg) and randomly assigned to three experimental treatments in a three-period crossover-design experiment. Dietary treatments consisted of Control; 8 kg of a commercial cereal-based compound, BUF1; control diet +70 g of a novel marine-based buffer (a mix containing only calcified seaweed and a marine source of magnesium oxide: see detailed analysis provided) and BUF2; control +140 g of the same marine-based buffer in a changeover design experiment. Experimental periods lasted for 35 d with 21 d for diet adaptation and a 14 d measurement period. In-dwelling reticulo-rumen pH probes recorded reticulo-rumen pH and temperature during d 58–63 (Period 2) and d 93–98 (Period 3) of this experiment. Cows fed BUF1 and BUF2 showed an increased milk yield of 1.20 kg/d and 1.07 kg/d respectively when compared to the Control diet (P = 0.004 and P = 0.012). There were increases in energy corrected milk yield (ECM) of 1.53 kg/d (P = 0.02) and 3.5% and 4% fat corrected milk (FCM) of 1.87 kg/d and 1.76 kg/d, respectively (P = 0.012), when cows were fed BUF2 compared to cows fed the Control. Number of minutes per treatment per day at reticulo-rumen pH < 5.8 and < 6.0 was significantly greater for cows fed Control compared to cows fed BUF2 (P<0.001). Results of this experiment suggest that supplementation with a novel marine-based rumen buffering product increased milk production and reduced the amount of time the reticulo-rumen was below pH 5.8 and 6.0 in grazing dairy cows supplemented with a cereal-based concentrate.