Meta analysis of responses of lactating cows to buffer supplementation

Abstract

Rumen acidosis is a common nutritional disorder inhigh yielding ruminants, especially in dairy cows.Buffer supplementation (BS) might be a way to limitdeleterous effects of acidosis. A meta analysis of dataextracted from literature (40 publications) allows toobtain some general laws of responses on performance,rumen and metabolic parameters. BS (by % in dry matterunit) increases significantly dry matter intake by 0.51 kg/d, raw milk yield by 0.52 kg/d and milk fat by 0.15%. BS increases rumen pH by 0.07 unit. Total volatilefatty acids are not affected by BS while molar percentageof propionate decreases and those of acetateand butyrate increase. Consequently the acetate: propionateratio increases significantly. It must be underlinedthat all these responses are strongly linked totheir initial values: BS is much more efficient in(sub)acidosis conditions. Blood pH tends to increase,blood bicarbonate concentration and urinary pHincrease significantly with BS. These observationsencourage to develop studies on the relationship betweenthese metabolic indicators of acid-base equilibriumand the rumen acidosic status, despite ofconsidering this latter separately.