Rumen Degradation and Availability of Various Amounts of Liquid Methionine Hydroxy Analog in Lactating Dairy Cows

Abstract

Ruminal escape of various amounts of methionine hydroxy analog [D,L-2-hydroxy-4-(methylthio)-butanoic acid (HMB)] was measured in an experiment designed as a 4 x 4 Latin square using four lactating dairy cows with cannula in the rumen and duodenum. The cows were fed a diet composed of corn silage, alfalfa haylage, rolled barley grain, canola meal, and blood meal, three times per day. The cows were fed the liquid analog each day for 1 wk before the experiment was started. On the day of the experiment, each cow received an intraruminal bolus dose of 0, 25, or 50 g of the liquid analog (Alimet feed supplement, 88% HMB) or 51.2 g of a dry calcium salt of the analog (86% HMB; MHA) mixed with 0.5 kg of ground barley grain. A liquid phase marker (Co-EDTA) was administered as a bolus dose into the rumen at the time of administration of the methionine hydroxy analogs. Rumen and duodenal contents, and blood serum were collected at 0, 1, 3, 6, 9, 12, and 24 h relative to the time of dosing. Rumen and duodenal samples were analyzed for Co and HMB, and serum was analyzed for free methionine. Fractional rate constants for the passage of the liquid marker (k(p)) and the decline of HMB concentration in the rumen (k(rHMB)) were determined by nonlinear regression. Liquid passage from the rumen was similar among the four analog treatments (0.136 +/- 0.012/h; mean +/- SEM). Ruminal escape of HMB as a percentage of the dose (100% x k(p)/k(rHMB)) did not differ between cows receiving 25, 50, and 51.2 g of the methionine analogs (42.5, 41.0, and 34.9 +/- 9.0%, respectively) and averaged 39.5%. Duodenal appearance of HMB as a percentage also did not differ between cows receiving 25, 50, and 51.2 g of the methionine analogs (16.2, 26.8, and 22.7%, respectively) and averaged 22%. Omasal absorption of HMB was variable ranging from 12.3 to 26.3% and averaged 17.6%. Serum methionine concentration peaked at 3 and 6 h after dosing and increased in proportion to the amount of the analog administered. It was concluded that 39.5% of the methionine hydroxy analog escaped rumen degradation, the percentage of the dose that escaped the rumen was not affected by the amount or form of the methionine analog fed, and the analog that escaped ruminal degradation was likely absorbed and metabolized to methionine.

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

“…Actually, HMB did not totally escape rumen microbial metabolism and could be a source of Met for rumen microorganisms. Previous studies indicated 40‐50% ruminal escape of HMB (Vázquez‐Añón et al ; Koenig et al ), which showed a significant amount of HMB was metabolized in the rumen. Because of the ruminal degradability, HMB could affect microbial fermentation by a direct stimulatory effect of Met on certain cellulolytic bacteria or through an indirect effect on the noncellulolytic species in the rumen (Martin et al ).…”

Meta-analysis of lactation performance in dairy cows receiving supplemental dietary methionine sources or postruminal infusion of methionine

“…On average, cows infused with dl-Met were provided with lower levels of Met; however, as this was assumed to be 100% absorbed, MP Met differences were comparable for dl-Met, Mepron, and Smartamine. Cows fed HMTBa were fed a higher amount of supplemental Met equivalent than cows fed the other sources; however, due to degradation of the product within the rumen (assuming 40% of HMTBa escaped rumen degradation; Koenig et al, 1999Koenig et al, , 2002Vázquez-Añón et al, 2001), predicted MP Met was not changed as much in HMTBa-fed cows.…”

“…Also missing from previous analyses are experiments that evaluated the use of HMTBa as a source of supplemental MP Met. Whereas the rumen escape of HMTBa has been debated in the literature (Koenig et al, 2002;Noftsger et al, 2005;Zanton et al, 2012), the production effects of HMTBa have been extensively investigated. However, a comprehensive estimate of the effectiveness of supplementation is unavailable for lactating dairy cows.…”

Effect of 2-hydroxy-4-methylthio-butanoic acid on ruminal fermentation, bacterial distribution, digestibility, and performance of lactating dairy cows

“…Limited data have suggested a possible effect of HM-TBa on rumen fermentation, fiber degradability, and microbial protein synthesis. With a reported ruminal degradability of 50% or more (Koenig et al, 1999(Koenig et al, , 2002Noftsger et al, 2005), HMTBa could affect microbial fermentation by a direct stimulatory effect of Met on certain cellulolytic bacteria or through an indirect effect on the noncellulolytic species in the rumen (Martin et al, 2013). Vazquez-Añon et al (2001) reported, for example, a quadratic increase in bacterial N outflow and the efficiency of bacterial N synthesis in continuous culture fermenters.…”