Assessment of blood sampling time points to determine the relative bioavailability of ruminally protected methionine supplements using the plasma free amino acid dose-response technique.

The calculation of the relative bioavailability (RBV) of rumen-protected AA supplements using the plasma free AA dose-response technique currently relies on blood samples obtained 2, 4, 6, and 8 h after the 0500 h feeding during the last 3 d of each period in Latin square experiments with cows fed every 8 h (0500, 1300, and 2100 h). The objective of this study was to determine if this current blood sampling protocol captures the changes that may occur in plasma Met concentrations within a 24-h day to adequately determine the RBV of Met from Smartamine M (SM). Five multiparous lactating Holstein cows were used in a 5 × 5 Latin square design with 7-d periods.

Effects of rumen-protected methionine supplementation on the performance of high production dairy cows in the tropics.

Increasing methionine availability in dairy cow diets during the first third of lactation may enhance their performance and health. The aim of this study was to determine the effect of supplementing rumen-protected methionine (Smartamine® M, SM) in a lactation diet with protein and energy levels calculated according to the literature. Seventy-six multiparous Holstein cows (39.

A 100-Year Review: Protein and amino acid nutrition in dairy cows.

Considerable progress has been made in understanding the protein and amino acid (AA) nutrition of dairy cows. The chemistry of feed crude protein (CP) appears to be well understood, as is the mechanism of ruminal protein degradation by rumen bacteria and protozoa. It has been shown that ammonia released from AA degradation in the rumen is used for bacterial protein formation and that urea can be a useful N supplement when lower protein diets are fed.