Sampling requirements for forage quality characterization of rectangular hay bales

Commercial lots of alfalfa (Medicago saliva L.) hay are often bought and so ld on the basis of forage quality. Proper sampling is essential to obtain a ccurate forage quality results for pricing of alfalfa hay, but information about sampling is limited to small, 20- to 40-kg rectangular bales. Our obj ectives were to determine the within-bale variation in 400-kg rectangular b ales and to determine the number and distribution of core samples required to represent the crude protein (CP), acid detergent fiber (ADF), neutral de tergent fiber (NDF), and dry matter (DM) concentration in commercial lots o f alfalfa hay. Four bales were selected from each of three hay lots and cor e sampled nine times per side for a total of 54 cores per bale. There was n o consistent pattern of forage quality variation within bales. Averaged acr oss lots, any portion of a bale was highly correlated with bale grand means for CP, ADF, NDF, and DM. Three lots of hay were probed six times per bale , one core per bale side from 55, 14, and 14 bales per lot. For determinati on of CP, ADF, NDF, and DM concentration, total core numbers required to ac hieve an acceptable standard error (SE) were minimized by sampling once per bale. Bootstrap analysis of data from the most variable hay lot suggested that forage quality of any lot of 400-kg alfalfa hay bales should be adequa tely represented by 12 bales sampled once per bale.