title: Performance and methane emissions of grazing Nellore bulls supplemented with crude glycerin.
abstract: Supplementation of grass-fed cattle with low-cost feeding alternatives may be an attractive way to improve efficiency of cattle production. We hypothesized that inclusion of crude glycerin (CG) in supplements provided to grass-fed cattle could improve feed conversion without negative effects on growth performance while reducing methane emissions. Our hypothesis was tested using Nellore bulls grazing tropical pasture ( = 50; initial BW of 427 ± 19.41 kg; age of 17 ± 2 mo) supplemented with increasing concentrations (0, 70, 140, 210, and 280 g/kg DM basis of supplement) of CG and corn gluten replacing corn grain. A second experiment was conducted using 10 ruminally cannulated Nellore steers (490.1 ± 47.8 kg BW; age of 25 mo) to assess the impact of different concentrations of glycerin in the supplement on ruminal VFA concentration. Inclusion of CG did not affect total DMI ( = 0.53), DMI of forage ( = 0.41), supplement DMI ( = 0.47), organic matter intake ( = 0.50), crude protein intake ( = 0.24), NDF intake ( = 0.49), GE intake ( = 0.50), NDF digestibility ( = 0.17), final BW ( = 0.17), LM area ( = 0.50), rib fat thickness ( = 0.87), or carcass gain ( = 0.13). The inclusion of CG in the supplement linearly increased ( < 0.001) the molar proportion of propionate, butyrate, and valerate; linearly decreased acetate ( = 0.001); and did not affect the molar proportion of isovalerate ( = 0.31) and isobutyrate ( = 0.63), thereby reducing the acetate to propionate ratio ( < 0.001). The increase of CG supplementation of young bulls in pasture had a quadratic effect on BW gain ( = 0.002), with lower BW gain with 140 g/kg DM of CG in the supplement and tended ( = 0.06) to improve G:F. Inclusion of CG did not affect ruminal CH emission expressed in kilograms per year ( = 0.74), grams per kilogram of DMI ( = 0.69), and grams per kilogram of carcass gain ( = 0.48). Crude glycerin supplementation was not effective as a strategy to reduce CH emission in grass-fed cattle. However, CG can be effectively used as a partial energy source in supplement of grazing cattle, promoting an improvement in feed efficiency.
authors.forename: E
authors.initials: E
authors.lastname: San Vito
authors.forename: J F
authors.initials: JF
authors.lastname: Lage
authors.forename: J D
authors.initials: JD
authors.lastname: Messana
authors.forename: E E
authors.initials: EE
authors.lastname: Dallantonia
authors.forename: R T S
authors.initials: RT
authors.lastname: Frighetto
authors.forename: R A
authors.initials: RA
authors.lastname: Reis
authors.forename: A J
authors.initials: AJ
authors.lastname: Neto
authors.forename: T T
authors.initials: TT
authors.lastname: Berchielli
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004063:Digestion; D005990:Glycerol / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008697:Methane / Q000378:metabolism*; D006109:Poaceae; D012417:Rumen / Q000378:metabolism; D003313:Zea mays
chemical_list: D008697:Methane; D005990:Glycerol