title: Effect of harvest date and variety on ruminal degradability of ensiled maize grains in dairy cows.
abstract: In this study we investigated the influence of harvest date and genotype on the ruminal degradability of the organic matter of ensiled maize grains. Grains of the varieties Avenir, Byzance, CGS 5104 and CGS 5107 from six different harvest dates were available; they are classified as intermediate types between flint and dent corn. The six harvest dates, during which time the dry matter content of the ensiled grains rose from 52% to 66%, extended from 1st September to 19th October. Assuming a passage rate of k = 0.08, the effective ruminal degradability declined in this period on average from 93% to just under 79%; variety-specific deviations also increased markedly during this period. The dry matter content (x, DM in %) of the ensiled grains had a profound influence on ruminal degradation: a highly significant curvilinear decline in ruminal degradability (y) was calculated at increasing DM levels (k = 0.08), which can be described by the equation y = -0.072x2 (+/- 0.010) + 7.417x (+/- 1.186) - 98.71 (+/- 34.58) (B = 0.96; sy.x[%] = 1.36). The ruminal degradability of ensiled maize grains is about 5-10% higher than that of fresh maize grains.
authors.affiliation: Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt, Department für Tierwissenschaften, Bereich Tierernährung, Technische Universität München, Hochfeldweg 4, D-85350.
authors.forename: T
authors.initials: T
authors.lastname: Ettle
authors.forename: P
authors.initials: P
authors.lastname: Lebzien
authors.forename: G
authors.initials: G
authors.lastname: Flachowsky
authors.forename: F J
authors.initials: FJ
authors.lastname: Schwarz
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D003902:Detergents; D004063:Digestion; D005260:Female; D005838:Genotype; D007700:Kinetics; D007774:Lactation / Q000378:metabolism / Q000502:physiology; D012417:Rumen / Q000378:metabolism*; D012621:Seasons; D012820:Silage; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: D003902:Detergents