The Effect of Protecting Lysine and Methionine with Condensed Tannin Added Into Total Mixed Ration on Efficiency of Microbial Protein Synthesis by Using an in Vitro Gas Production Approach

Abstract

An in vitro study investigating the effects of adding CT-protected Lysine (Lys) and Methionine (Met) on gas production and efficiency of microbial protein synthesis (EMPS) of total mixed ration (TMR) was conducted at Animal Nutrition Laboratory.  TMR were composed of concentrate and maize stover at 50:50 ratios in DM basis.

The experiment used 4x4 factorial randomized design and 3 replications. The first factor  was level of Lys and Met (3 g Lys- 1 g Met; 5 g Lys- 1.67 g Met; 7 g Lys- 2.33 g Met; 9 g Lys- 3 g Met) and  the second factor  was level or percentage of  CT  (0%, 6%, 8% and 10%) of Lys and Met.

Parameters measured were cumulative gas production recorded at 0, 2, 4, 8, 12, 16, 24, 36 and 48 h, DMD and OMD of residues, concentrations of NH₃ and VFAs, and EMPS. The results showed that there was interaction effect between levels of Lys-Met and CT on cumulative gas production and b value, with treatment A1B3 (3g Lys + 1g Met) + 8% CT) being the lowest (106.2 ml 121.9 ml) and A4B1 (9g Lys + 3g Met) being the highest (121.9 ml and 136.8 ml). Increasing level of  Lys-Met alone significantly increased cumulative gas production, DMD, and ammonia-N, but did not increase c value, OMD , concentrations of acetic, propionic and butyric acids, total VFA, ratio of C2/C3, and EMPS. Increasing level of CT reduced cumulative gas production; b value, ammonia-N, C2, C3, C4, and total VFA, with 0% CT and 10% CT being associated with the highest and the lowest value of those parameters. The highest value of EMPS was found on treatment A1B4 (3g Lys + 1g Met+10% CT; 50.3 g N/kg DOM). It can be concluded that CT is able to protect Lys-Met from being fermented in the rumen, hence improving EMPS value.

Keywords: lysine, methionine, CT, in vitro gas production