An increase in dietary lipid content from different forms of double‐low rapeseed reduces enteric methane emission in Datong yaks on the Qinghai‐Tibetan Plateau

Abstract

Enteric methane (CH4) emission in cattle generally decreases by approximately 1 g/g dry matter intake (DMI) with an increase in dietary lipids of 10 g/kg dry matter (DM). The effect of dietary lipids on CH4 emission in yaks has not been reported and is the subject of this study. Four Datong yaks were used in a 4 × 4 Latin‐square design in which the four treatments included restricted intakes of double‐low rapeseed differing in form and lipid (ether extract—EE) content: (a) rapeseed meal (EE 32.6 g/kg DM); (b) rapeseed meal and rapeseed cake (EE 45.8 g/kg DM); (c) rapeseed meal and whole cracked rapeseed (EE 54.5 g/kg DM) and (d) rapeseed meal and rapeseed oil (EE 62.7 g/kg DM). The digestibility of feed components did not differ among treatments. The ruminal total volatile fatty acids (p = .082) and acetic acid (p = .062) concentrations tended to be lowest in yaks consuming the diet with highest lipid content. In addition, CH4 production was lowest in this group (p = .004), and declined by 1.75 g/g DMI per 10 g/kg DM reduction in dietary lipid content, a rate substantially faster than in cattle.

Effects of Concentrate Supplementation on Growth Performance, Rumen Fermentation, and Bacterial Community Composition in Grazing Yaks during the Warm Season

“…For determination of VFAs (acetic, propionic, isobutyric, butyric, isovaleric, and vleric acids), a 2 mL sample of thawed ruminal fluid was placed in a centrifuge tube, mixed uniformly with 0.5 mL of 25% ortho-phosphoric acid, and clarified by centrifugation at 13,000× g rpm at 4 °C for 15 min before analysis by gas chromatography (7980 A; Agilent Technologies, USA). The determination conditions were as follows: column temperature (FFAP 30 m × 0.32 mm × 0.5 um) 110 °C, inlet temperature 220 °C, detector temperature 220 °C, splitting ratio 30:1, high purity nitrogen as the carrier gas, as described by Zhang et al [ 23 ]. Concentrations of ammonia nitrogen (NH3-N) were determined according to a phenol hypochlorite assay, as described by Broderick et al [ 24 ], and ruminal microbial protein (MCP) was determined based on the method described by Makkar et al [ 25 ].…”