Rumen Fermentation Characteristics of High- and Low-Residual Feed Intake Cattle Grazing Pasture: An In Vitro Study

Abstract

Residual Feed Intake (RFI) is an indicator of feed efficiency in beef cattle and is increasingly used in genetic selection programs. The main advantage of RFI is its relative independence from body size and growth rate. Although RFI has been widely applied in controlled feedlot systems, its use in grazing systems remains under debate. This study aims to evaluate the difference in fermentation rumen results from efficient or low RFI (LRFI) and inefficient or high RFI (HRFI) cattle grazing pastures. This study used the in vitro method of gas production. Ruminal fluid and feed substrate were taken from cattle and forage from the study site. The results showed that the average total gas production and total VFA were significantly higher (P< 0.05) in LRFI cattle compared to HRFI cattle; the total gas production of Low RFI cattle was (15.87 mL), and high RFI cattle was (14.19 mL). The total VFA of LRFI cattle is 5.78 mmol, and HRFI cattle is 5.07 mmol. In contrast, methane production did not differ significantly (P > 0.05) between the two groups. These findings show that the LRFI cattle grazing system still showed better fermented rumen results than the HRFI cattle.