Early lactational response to supplemental protein by dairy cows fed grass-legume forage.

A total of 24 primiparous and 46 multiparous Holstein cows were in two trials to determine the influence of concentration of dietary protein on performance during early lactation. Treatments were 13.5 or 16.5% dietary crude protein for the first 12 wk of lactation. Complete mixed diets of grass-legume forage and concentrates were fed for ad libitum consumption. Treatment patterns repeated across trials. Yields of milk and 3.5% fat-corrected milk, intake of dry matter, and returns over feed costs were improved by feeding the diet with 16.5% crude protein. Percent milk fat, body weight change, and reproductive performance were unaffected by treatment. The results demonstrate benefit, during early lactation, from supplementing protein to grass-legume based diets containing 13.5% crude protein. Performance responses to increased concentrations of dietary crude protein during early lactation appear greater for multiparous than primiparous cows.