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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #102560
Title: SAMPLING STRATEGIES FOR STUDIES OF ALFALFA FORAGE QUALITY

Author
item JEWETT, JANE - UNIVERSITY OF MINNESOTA
item SHEAFFER, CRAIG - UNIVERSITY OF MINNESOTA
item MOON, R - UNIVERSITY OF MINNESOTA
item Lamb, Joann

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Many researchers have worked on improving feed value of alfalfa forage by selecting plants with increased protein and reduced indigestible fiber. Well known laboratory procedures are used to estimate these feeding value components of alfalfa hay, but little research has been done on how forage sample collection from the field influences these estimates of forage quality. Samples hand-clipped from several locations within a plot and gra samples from mechanically cut swaths of alfalfa forage gave similar estimates of forage quality. Therefore, plant breeding programs creating new alfalfas with improved forage quality can use the simpler and less time consuming method of grab samples from mechanically harvested alfalfa hay compared to hand-clipped samples to improve the feed value of alfalfa hay.

Technical Abstract: Research is scarce on sampling techniques for field studies of alfalfa forage quality. There are standard formulas available for estimating the number of samples needed for reducing error in a study, but little is known about the impact of sampling strategies on forage quality. Our objectives were to compare the strategies of manual harvesting from small areas within nplots and of sampling from mechanically harvested forage, and to determine whether the location of hand clipped samples within a plot affects forage quality. Forage samples from field plots were taken from swaths of mechanically clipped forage (grab samples) and from hand-clipped areas within plots (area samples). Samples were analyzed for crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro digestible dry matter (IVDDM), and acid detergent lignin (ADL). Forage quality was higher for area samples than for grab samples in one experiment, but the reverse was true in a second experiment. Neither sampling strategy consistently gave smaller standard errors for forage quality prediction. There was no interaction between alfalfa entries and sampling strategy, indicating that both sampling strategies produced similar rankings of entries. We found no effect of within-plot location of sampling on forage quality. Three area samples or two grab samples per plot from two replicates, or one of either type of sample per plot from three replicates would provide an acceptable standard error for comparison of alfalfa entries for CP, ADF, and NDF.