Influence of weather conditions during swath drying on the nutritive value of hay

The influence of weather conditions during swath drying on the composition and nutritive value of hay was investigated at seven plots of conditioned Gramineae hay. Hays were tedded 1-2 times a day except on rainy days. Five of the hays were sampled and analyzed daily, two at cutting and baling and on one other day only. One hay was harvested in fine weather and dried in just over two days. The protein content decreased, but the sugar content remained unchanged. The f.u. value (fattening feed unit = 0.7 x starch unit) fell 4 %, the DCP value 12 %. A second hay was exposed to eight days of rain. The main changes were a rise in lignin content and decrease in digestibility. The protein and sugar contents and the pepsin solubility of protein changed very little. The f.u. value fell 18 %, the DCP value2 %. Five other hays were 6-12 days as swath in variable rainy and dry weather conditions. The quality changed depending on the time, duration and amount of rain. The decreases of f. u. and DCP values were 10-30 % and 8-28 %, respectively. The contents of sugar, ash and crude fat fell 31-64, 3-51 and 36-39%, while the crude fibre content rose 6-23 %. The reduction in the DCP value in bad weather depended more on the decrease of pepsin solubility of protein than on the decrease of protein content. The potassium content of hay proved to be a good measure of the leaching due to rain. In the present hays the potassium content decreased 0-79 %. The average total losses calculated on the basis of lignin content of hay were as follows (ranges in parenthesis): DM 22 % (12-29), F. u. 35 % (15-51), DCP 32 % (22-49), sugars + fructosan 50 % (12-74) and ash 33 % (18-65)