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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #160089
Title: QUALITY OR YIELD: WHICH IS MOST CRITICAL

Author
item Jensen, Kevin
item Waldron, Blair
item ASAY, K - ARS - RETIRED

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2002
Publication Date: 11/10/2002
Citation: Jensen, K.B., Waldron, B.L., Asay, K.H. 2002. Quality or yield: which is most critical. Agronomy Abstracts.

Interpretive Summary: As water resources become limiting, the need to produce stable amounts of highly nutritional forage increases. An understanding of how levels of irrigation affect crude protein (CP), digestible neutral detergent fiber (dNDF), in vitro true digestibility (IVTD), and neutral detergent fiber (NDF) is critical in pasture forage management. Cultivars of orchardgrass (Dactylis glomerata L.) and perennial ryegrass (Lolium perenne L.) were established under a line-source irrigation system to evaluate the effect of five water levels (WL) and three harvest dates on concentrations of CP, dNDF, IVTD, and NDF. Perennial ryegrass forage had higher CP, dNDF, IVTD, and lower NDF concentrations than orchardgrass at all harvest dates and within WLs. However, due to decreased DMY in perennial ryegrass cultivars, orchardgrass cultivars produced more total (kg ha-1) CP, dNDF, IVTD, and NDF. The most notable trend in nutrutional value across WLs was the near linear increase in CP ranging from 175 g kg-1 at the wettest WL to 217 g kg-1 at the driest WL. Digestible NDF ranged from 709 g kg-1 to 757 g kg-1 at corresponding WLs. These trends were particularly evident later in the growing season. Orchardgrass maturity (early vs late) had little effect on forage nutritional characteristics across WLs. Combined over WLs, tetraploid perennial ryegrass cultivars averaged higher concentrations of CP, IVTD, dNDF, and lower NDF values when compared to diploid cultivars. In general, as water stress increased, forage nutritional value (i.e., CP and dNDF) increased.

Technical Abstract: As water resources become limiting, the need to produce stable amounts of highly nutritional forage increases. An understanding of how levels of irrigation affect crude protein (CP), digestible neutral detergent fiber (dNDF), in vitro true digestibility (IVTD), and neutral detergent fiber (NDF) is critical in pasture forage management. Cultivars of orchardgrass (Dactylis glomerata L.) and perennial ryegrass (Lolium perenne L.) were established under a line-source irrigation system to evaluate the effect of five water levels (WL) and three harvest dates on concentrations of CP, dNDF, IVTD, and NDF. Perennial ryegrass forage had higher CP, dNDF, IVTD, and lower NDF concentrations than orchardgrass at all harvest dates and within WLs. However, due to decreased DMY in perennial ryegrass cultivars, orchardgrass cultivars produced more total (kg ha-1) CP, dNDF, IVTD, and NDF. The most notable trend in nutritional value across WLs was the near linear increase in CP ranging from 175 g kg-1 at the wettest WL to 217 g kg-1 at the driest WL. Digestible NDF ranged from 709 g kg-1 to 757 g kg-1 at corresponding WLs. These trends were particularly evident later in the growing season. Orchardgrass maturity (early vs late) had little effect on forage nutritional characteristics across WLs. Combined over WLs, tetraploid perennial ryegrass cultivars averaged higher concentrations of CP, IVTD, dNDF, and lower NDF values when compared to diploid cultivars. In general, as water stress increased, forage nutritional value (i.e., CP and dNDF) increased.