The effect of calcareous marine algae, with or without marine magnesium oxide, and sodium bicarbonate on rumen pH and milk production in mid-lactation dairy cows

摘要

Two experiments were carried out to evaluate differentdietary buffers and their influence on (1) rumen pHin dairy cows and (2) milk production in dairy cows.The supplements included were calcareous marine algae(CMA; Lithothamnion calcareum), with or withoutmarine magnesium oxide (MM; precipitated magnesiaderived from seawater), and sodium bicarbonate (SB).Dietary treatments in experiment 1 consisted of thecontrol [32.9% starch and sugar, and 19.9% neutraldetergent fiber from forage per kg of dry matter (DM)]including no dietary buffer (CON); the control plus0.45% DM CMA (CMA); the control plus 0.45% DMCMA and 0.11% DM MM (CMA+MM); the controlplus 0.9% DM SB (SB). Diets were formulated to a drymatter intake (DMI) of 18 kg per cow/d. Dietary treatmentsin experiment 2 also consisted of CON (28.3%starch and sugar, and 23% neutral detergent fiber fromforage per kg of DM), CMA, CMA+MM, and SB andwere formulated to achieve identical intakes of experimentalingredients (80 g of CMA, 80 g of CMA plus 20g MM, and 160 g of SB per cow/d) with a DMI of 22.6kg per cow/d. Experiment 1 used 4 rumen-cannulateddairy cows in a 4 × 4 Latin square design. Rumen pHwas measured over five 2-h periods, following feeding,using rumen pH probes. In experiment 2, 52 multiparousand 4 primiparous cows (62.7 ± 3.4 d in milk)were assigned to 4 experimental treatments for 80 d.Both CMA treatments maintained a greater meanrumen pH than the CON during 4 of the 5 periodsfollowing feeding and the CON had a greater numberof hours below rumen pH 5.5 compared with all othertreatments. Dry matter intakes tended to be higheron the SB compared with CON. The CMA treatmentincreased the production of milk fat and protein yield(kg/d) compared with all other treatments. Both CMAand CMA+MM increased milk fat yield compared withCON but were similar to each other and SB. Proteinyield was highest in the CMA treatment compared withCON, CMA+MM, and SB. All 3 buffer treatments increasedmilk fat concentration compared with CON butdid not differ from each other. The SB treatment reducedmilk protein concentration and milk productionefficiency, energy-corrected milk per kilogram of DMI.Results indicate that the addition of CMA can benefitmilk fat and protein production when included in dietsbased on typical feedstuffs of the northern Europeanregion. The use of CMA when compared with SB, insuch diets, can increase milk protein production andmilk production efficiency.