Abstract
The objective of this study was to compare the forage nutritive value of cool-season perennial grasses and legumes with that of warm-season annual grasses grazed by organic dairy cows. Two pasture systems were analyzed across the grazing season at an organic dairy in Morris, Minnesota. Pasture system 1 included perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), meadow bromegrass (Bromus riparius Rehmann), meadow fescue (Schedonorus pratensis (Huds.) P. Beauv), alfalfa (Medicago sativa L.), white clover (Trifolium repens L.), red clover (Trifolium pratense L.), and chicory (Cichorium intybus L.). Pasture system 2 was a combination of system 1 and monocultures of warm-season grasses (sorghum-sudangrass (Sorghum bicolor [L.] Moench subsp. drummondii [Steud.]) and teff (Eragrostis tef L.)). Across the grazing season, forage yield was 39% greater for system 2 than system 1 due to greater forage yield during the summer. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were similar for cool-season and warm-season grasses. Warm-season grasses had greater forage yield during the summer months compared with cool-season grasses and legumes. The total tract NDF digestibility (TTNDFD) varied by month and year across the study for both pasture systems. Overall, weather may affect the forage nutritive value for both cool-season perennial grasses and legumes and warm-season annual grasses.
Highlights
Pasture-based dairy production may be an economically competitive management system, with benefits that include less labor, lower investments of facilities, and comparable net income to confinement dairy systems [1]
There was 38% greater seasonal forage yield (p < 0.05) in pasture system 2 compared with pasture system 1 (Table 2)
The least squares means for the seasonal forage nutritive value of Cool-season perennial (CSP) and Warm-season annual (WSA) grasses
Summary
Pasture-based dairy production may be an economically competitive management system, with benefits that include less labor, lower investments of facilities, and comparable net income to confinement dairy systems [1]. The profitability of grazing dairy farms is determined by pastures that produce a large quantity of high nutritive value forage for cattle to graze throughout the grazing season. Dry matter intake (DMI), and milk production, is controlled by forage biomass [2]. Organic dairy cattle in the USA require at least 120 d of grazing, with 30% of their daily dry matter intake from pasture according to the USDA National Organic Pasture guidelines [3]. Grazing represents a low-cost strategy for feeding dairy cattle during the summer. Cool-season perennial (CSP) grasses are the foundation of dairy pastures, which are typically productive between May and September in the northern half
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