The Effect of Guanidinoacetic Acid Addition on In Vitro Rumen Fermentation Characteristics and Gas Production of Early- and Late-Stage Sheep-Fattening Diets

This study explores whether guanidinoacetic acid (GAA) addition can regulate nutrient degradability, rumen fermentation characteristics, and gas composition in two sheep-fattening diets. A 2 × 8 factorial vitro culture was examined to determine the effects of GAA at following levels 0%, 0.03%, 0.05%, 0.07%, 0.09%, 0.11%, 0.13%, 0.15% total mixed rations (T1 diet: early fattening stage diet; T2 late diet). After 72 h incubation diets with liquid obtained from six rumen-cannulated lambs, diet exhibited higher dry matter (DM) digestibility, cumulative production (GP72), asymptotic production(A), longer time which half is reached (C). However, it a lower acetic ratio acetate propionate than T1. quadratic increase occurred neutral detergent fiber (NDF) (ADF) maximum point occurring 0.09% group. The kinetic result indicated that increasing level resulted mainly an GP72 A, for T1 0.07–0.09% diet. Moreover, did not affect pH, proportion any volatile acid, or composition, but when were increased, microbial crude protein (MCP), ammonia nitrogen (NH3-N), fatty (TVFA) content relationship. highest MCP contents seen 0.11% groups, while NH3-N TVFA 0.07% In summary, appropriate ranged 0.11%.