title: Effect of maturity and hybrid on ruminal and intestinal digestion of corn silage in dry cows.
abstract: The aim of this study was to evaluate the effect of stage of maturity at harvest on extent of starch, neutral detergent fiber (NDF), and protein digestion, and rumen fermentation in dry cows fed whole-plant corn silage from different hybrids. Four nonlactating Holstein cows cannulated at the rumen and proximal duodenum were fed 4 corn silages differing in hybrid (flint vs. flint-dent) and maturity stage (early vs. late) in a 4 × 4 Latin square design. From early to late maturity, starch content increased (from 234.5 to 348.5 g/kg), whereas total-tract (99.7 to 94.5%) and ruminal starch digestibility (91.3 to 86.5%) decreased significantly. The decrease in ruminal starch digestibility with increasing maturity was similar between hybrids. No effects were found of maturity, hybrid, or maturity × hybrid interaction on total-tract NDF digestibility, ruminal NDF digestibility, true digestibility of N and organic matter in the rumen, or microbial synthesis. Harvesting at later maturity led to increased ruminal ammonia, total volatile fatty acid concentrations, and acetate/propionate ratio but not pH. This study concludes that delaying date of harvest modifies the proportions of digestible starch and NDF supplied to cattle. Adjusting date of corn harvest to modulate amount of rumen-digested starch could be used as a strategy to control nutrient delivery to ruminants.
authors.affiliation: INRA, UMR1213 Herbivores, F-63122 Saint-Genès-Champanelle and Clermont Université, VetAgro Sup, UMR Herbivores, BP 10448, F-63000, Clermont-Ferrand, France; ARVALIS-Institut du Végétal, Station Expérimentale de la Jaillière, 44370 La Chapelle-Saint-Sauveur, France.
authors.forename: J
authors.initials: J
authors.lastname: Peyrat
authors.affiliation: INRA, UMR1213 Herbivores, F-63122 Saint-Genès-Champanelle and Clermont Université, VetAgro Sup, UMR Herbivores, BP 10448, F-63000, Clermont-Ferrand, France.
authors.forename: R
authors.initials: R
authors.lastname: Baumont
authors.affiliation: INRA, UMR1213 Herbivores, F-63122 Saint-Genès-Champanelle and Clermont Université, VetAgro Sup, UMR Herbivores, BP 10448, F-63000, Clermont-Ferrand, France.
authors.forename: A
authors.initials: A
authors.lastname: Le Morvan
authors.affiliation: INRA, UMR1213 Herbivores, F-63122 Saint-Genès-Champanelle and Clermont Université, VetAgro Sup, UMR Herbivores, BP 10448, F-63000, Clermont-Ferrand, France. Electronic address: pierre.noziere@clermont.inra.fr.
authors.forename: P
authors.initials: P
authors.lastname: Nozière
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D004043:Dietary Fiber / Q000378:metabolism*; D004063:Digestion; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005260:Female; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000378:metabolism; D012417:Rumen / Q000378:metabolism; D012820:Silage / Q000032:analysis*; D013213:Starch / Q000378:metabolism; D003313:Zea mays
chemical_list: D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D013213:Starch
keywords: corn silage; neutral detergent fiber; ruminal digestion; starch