Effects of Methionine and Lysine on Fermentation In Vitro and In Vivo, Nutrient Flow to the Intestine, and Milk Production

Abstract

Three experiments were conducted to investigate the feasibility of using crystalline methionine and lysine as protein supplements for lactating Holstein cows. In the first experiment, Met (dl-methionine) and Lys (l-lysine-HCl) were added to diets used in continuous culture bioreactors to estimate optimal concentrations for use in subsequent in vivo experiments. The second experiment measured ruminal fermentation and nutrient flow to the small intestine when Met and Lys were top-dressed on diets fed to nonlactating cows. The third experiment measured lactation performance when Met and Lys were added to diets fed to late-lactation cows. Providing 0.29 and 2.27% of dry matter as Met and Lys, respectively, provided the largest improvement in fermentation in vitro and these concentrations were used in subsequent experiments. When Met and Lys were top-dressed on diets fed to nonlactating cows, no changes in total tract N digestion were observed. No changes in microbial protein production or ruminal fermentation were observed. Adding Met and Lys did not change production or efficiency of production of milk or milk components by late lactation cows. These data indicate that providing supplemental Met and Lys during late lactation does not significantly improve the protein status of the cow and therefore may not improve milk production.

Effects of addition of Aspergillus oryzae culture and 2‐hydroxyl‐4‐(methylthio) butanoic acid on milk performance and rumen fermentation of dairy cows

“…It was observed that responses of HMB (40‐50% protection of rumen degradation) on rumen fermentation were variable. The rumen volatile fatty acid (VFA) proportion was not influenced by added HMB in some studies (Vázquez‐Añón et al ; Wilson et al ), while the change in rumen VFA profile was observed in other studies (Noftsger et al ; Chung et al ).…”

Effects of Aspergillus Oryzae Culture and 2-Hydroxy-4-(Methylthio)-Butanoic Acid on In vitro Rumen Fermentation and Microbial Populations between Different Roughage Sources

“…However, the impact of HMB on rumen fermentation seems highly variable and remains unclear. Although addition of HMB improved microbial protein synthesis (Vázquez-Añón et al, 2001), some researchers found no changes in volatile fatty acid (VFA) proportions by HMB (Vázquez-Añón et al, 2001; Wilson et al, 2008), whereas others reported changes in VFA profile (Noftsger et al, 2003; Chung et al, 2006). In addition, the mechanisms by which HMB could impact microbial digestion in the rumen are not yet clear.…”

Effects of rumen‐protected methionine on milk production in early lactation dairy cattle fed with a diet containing 14.5% crude protein

“…On the other hand, Chung et al. () reported in an in vitro experiment that the contents of total VFAs and some individual VFAs were altered by the addition of rumen‐protected Met. With the exception of the values for N, the apparent digestibility percentages (Table ) were close to previous findings: dry matter and organic matter, (Ha & Kennelly, ; Miyaji, Matsuyama, Hosoda, & Nonaka, ), ether extract, NDFom and ADFom (Miyaji & Matsuyama, ; Miyaji et al., ).…”