Post-ruminal effects of rumen-protected methionine supplementation with low protein diet using long-term simulation and in vitro digestibility technique

Imtiaz Hussain Raja Abbasi,Farzana Abbasi,Mohamed E Abd El-Hack,Junhu Yao,Yangchun Cao,Ayman A Swelum

doi:10.1186/s13568-018-0566-7

Abstract

Microbial degradation in the rumen and dietary availability of methionine amino acid have been reported as limiting in dairy ruminants. The aim of the present study was to examine the post-ruminal effects of feeding ruminants different concentrations of rumen-protected methionine (RPM) in low crude protein diets using the long-term rumen simulation method (Rusitec) followed by in vitro abomasum and ileum digestibility technique. The experiment contained four treatment groups: (1) high protein, without RPM supplementation (HP); (2) low protein, without RPM supplementation (LP); (3) low protein supplementation with low RPM (LPLM); and (4) low protein supplementation with high RPM (LPHM) mixed per 20 ± 0.04 g basal diet in every fermenter. The results showed that the LPLM and LPHM groups had significantly higher disappearance of crude protein and neutral detergent fiber in the abomasum and ileum than the HP treatment (P < 0.05) and were the same as the LP group (P > 0.05). The proportions of short-chain fatty acids and total volatile fatty acids in the abomasum and ileum were the same between the LPHM and HP groups (P > 0.05); however, the LPLM group was found to be significantly (P < 0.05) lower than the HP group and similar to the LP group (P > 0.05). Rusitec pH before or after changing feed bags and daily ammonia nitrogen production in the abomasum and ileum were non significantly (P > 0.05) different among all groups. In conclusion, RPM supplementation with low crude protein diets promoted post-ruminal digestibility and production of volatile fatty acids.

Highlights

Proteins, amino acids profiles, are the most limiting nutrient for milk production in ruminants with high genetic merit
The present study evaluated the post-ruminal effects of different supplementation levels of rumen-protected methionine (RPM) with low protein on digestibility, volatile fatty acids, NH3-N, and total tract digestibility using the rumen simulation technique (Rusitec) and in vitro techniques
The post-ruminal disappearance of crude protein (CP) and aNDF were significantly higher in low protein supplementation with low RPM (LPLM) and low protein supplementation with high RPM (LPHM), but no effects were found on dry matter (DM), acid detergent fiber (ADF), and gross energy (GE) with RPM

Summary

Introduction

Amino acids profiles, are the most limiting nutrient for milk production in ruminants with high genetic merit. Feed is a rich source of proteins; it is hard to digest and animals cannot maintain the amino acids (AA) balance between the high production of milk and supplementation of free AA and the balance of essential AA, which limits the key methyl donor, methionine, in dairy ruminants. In this situation, RPAA supplementation is a common method to counteract AA deficiency in dairy cow diets (Abbasi et al 2018). Several techniques have been developed to ensure the proper supply of methionine including encapsulation or matrix protection of methionine (Patton 2010) into the diets of ruminants to balance energy by increasing glucose production, promote hepatic oxidation of AA, or directly endorse protein synthesis

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