2,6-Diaminopimelic acid as a biological marker of rumen synthesis and fermentation capacities in the transition period and early lactation of dairy cows

Abstract

The experiment was conducted to evaluate the effect of different types of available nutrients of total mix rations on fermentation and synthesis capacities of the rumen in Holstein dairy cows divided into groups in the transition period (± 3 weeks after parturition) and early lactation (60–80 days in milk). The diets were fed as a total mixed ration. Results obtained with feeding Diet C (high concentration of available nutrients) to dairy cows confirmed a significant increase in 2,6-diaminopimelic acid from the initial mean 2.2 μg/ml at 21 days before calving to 6.2 μg/ml (P < 0.01) at 21 days after calving or 7.6 μg/ml (P < 0.01) at early lactation, and a parallel significant increase in the concentration of volatile fatty acids (P < 0.01). The concentration of propionic acid increased from the initial mean 25.3 to 39.3 mmol/l (P < 0.01) in the transition period, and to 43.1 mmol/l at early lactation (P < 0.01). All indicators of rumen fermentation and synthesis determined in dairy cows with Diet B (low concentration of available nutrients) of the total mix ration according to productive phases were not significant. High regression coefficients of examined indicators of 2,6-diaminopimelic acid to volatile fatty acid (r = 0.813), propionic acid (r = 0.780) and acetic acid (r = 0.635) indicate direct correlation between fermentation and synthesis activities of the rumen. Our results show that 2,6-diaminopimelic acid appears as a perspective marker for the monitoring and evaluation of the synthesis function of the rumen and production of bacterial biomass under breeding conditions.