title: Effect of ensiling and silage additives on fatty acid composition of ryegrass and corn experimental silages.
abstract: Two experiments were conducted using laboratory mini-silos to study the effect of ensiling and silage additives on fatty acid (FA) composition, including minor or unusual FA, of ryegrass and corn silages. Ryegrass was ensiled for 12 wk with no additives, with the addition of a bacterial inoculant or formic acid. Corn was ensiled for 9 wk without additives, with the addition of a bacterial inoculant or calcium formate. Ensiling affected both total FA content and FA composition of ryegrass silages. Total FA concentration increased (P < 0.001) during ryegrass ensiling. The proportions (g/100 g of total FA) of the major unsaturated FA, 18:3n-3 and 18:2n-6, were not affected (P > 0.05) by ensiling. However, their concentration (mg/g of DM) in silages was greater (P=0.017 and P=0.001, respectively) than in fresh ryegrass. Two 18:2 FA (trans-11,cis-15 and cis-9,cis-15) that were not originally present in the fresh ryegrass were detected in silages. Silage additives affected the FA composition of ryegrass silages, mostly by increasing the proportions of SFA, but not on total FA concentration. Ensiling did not affect (P=0.83) total FA content of corn silages; however, FA composition was affected, mostly by decreasing the proportions of 18:2n-6 and 18:3n-3. Silage additives had no effect on corn silage FA composition. Exposing corn silages to air resulted in no oxidation of FA or reduction in total FA content or composition.
authors.affiliation: Instituto Nacional dos Recursos Biológicos (INRB), Unidade de Produção Animal, Fonte-Boa, 2005-048 Vale de Santarém, Portugal.
authors.forename: S P
authors.initials: SP
authors.lastname: Alves
authors.forename: A R J
authors.initials: AR
authors.lastname: Cabrita
authors.forename: E
authors.initials: E
authors.lastname: Jerónimo
authors.forename: R J B
authors.initials: RJ
authors.lastname: Bessa
authors.forename: A J M
authors.initials: AJ
authors.lastname: Fonseca
mesh_terms: D000818:Animals; D005227:Fatty Acids / Q000737:chemistry; D005285:Fermentation; D005516:Food Microbiology; D005561:Formates / Q000737:chemistry; D008129:Lolium / Q000737:chemistry*; D012820:Silage / Q000032:analysis*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D005561:Formates; C030544:formic acid