Effect of rumen-protected methionine and reduced crude protein in lactating mediterranean buffaloes diet

Sixteen Mediterranean homogenous lactating buffaloes were divided into low protein (LP) and high protein (HP) groups of eight animals each. Groups were fed for 120 days two isoenergetic diets (0.90 Milk FU/kg DM) with different crude protein (CP) contents and rumen protected methionine (RPM) supplement. Milk yield and quality were determined. Faecal, blood, and urine samples were collected for the detection of urea and insulin in plasma; total-N, urea-N, and creatinine in urine; and total-N and N-digestibility in the faeces. To investigate rumen microbial diversity four cannulated Mediterranean buffalo cows were fed LP and HP diets according to a cross over design. Rumen samples, were analyzed for pH, microbial population quantity and diversity using classical and molecular techniques including DGGE and Q-PCR. Milk yield, protein, casein and fat content were similar in the two groups. Milk urea level was significantly lower in LP group. Both urea level in plasma and urea-N in urine were significantly higher in the HP. The total organic nitrogen excreted detected in urine and manure was higher in the HP group. The protein level reduction in diet supplemented with RPM seems to negatively affect the growth fungi and protozoa and methane production can be reduced by reducing rumen ciliate protozoa. Moreover these results indicate that the use of a low CP, RPM supplemented diet did not negatively affect milk production or quality, and reduced the nitrogen quantity excreted with urine and faeces, thus contributing to reduce the impact of buffalo herds on the environment.