Species and Stockpile Initiation Date Effects on Yield and Nutritive Value of Irrigated Cool-season Grasses

• Published in: Agronomy journal 2008-07, Vol.100 (4), p.931-937
• Main Authors: Volesky, J.D, Anderson, B.E, Stockton, M.C
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; cool season grasses; crop yield; crude protein; dry matter accumulation; forage crops; forage grasses; forage stockpiling; Fundamental and applied biological sciences. Psychology; grazing; harvest date; in vitro digestibility; irrigated farming; neutral detergent fiber; Nutritive value; pastures; species differences; weathering
• ISSN: 0002-1962; 1435-0645
• DOI: 10.2134/agronj2007.0312

Stockpiling forage for fall and winter grazing can extend the grazing season and reduce costs associated with harvesting, storing, and feeding forages. The objectives of this study were to determine species, stockpile initiation date, and winter harvest date effects on yield and nutritive value of eight cool-season grasses grown under irrigated conditions near North Platte, NE. Treatments included stockpile initiation dates of 15 July or 15 August and winter harvest dates of mid-November, December, January, and February arranged in a split-plot design. Stockpiled dry matter (DM) yield for the eight grass species ranged from 3.79 to 5.19 Mg ha-1 in 2005 and from 3.68 to 4.54 Mg ha-1 in 2006. Delaying initiation of stockpiling from 15 July to 15 August resulted in 30% less DM yield in November (P < 0.05). In 2005, stockpiled DM yield declined 18% from November to February while the decline was 24% for the same period in 2006. Species did not respond consistently to treatment effects for nutritive value of the stockpiled herbage. Herbage crude protein (CP) in November and December was greater when stockpiling was initiated in August (132 g kg-1) compared with July (112 g kg-1; P < 0.01). Initiating stockpiling in August resulted in greater in vitro dry matter digestibility (IVDMD) and lower neutral detergent fiber (NDF) throughout the winter period (P < 0.05). Late summer and fall growth of irrigated cool-season grasses and retention of adequate levels of nutrients supports their possible use as stockpiled forages in this area. However, cost-effectiveness of stockpiling grazing declines as hay value increases. Stockpiled forage grazing during the early part of the winter period (November and December) would be most advantageous because of weathering losses.