Quality in Roughages. I. Factors which Influence Hay Composition and Quality

Abstract

Summary Average air temperature during the growing season was negatively correlated with moisture in the green hay and with ether extract, total ash and sugar in the dry matter. Amounts of rainfall and sunshine during the growing season were without substantial effect on the composition of these hays. The principal loss during curing of these hays was in carotene; exposure to bright sunlight was more destructive of carotene than was a moderate amount of rain. Protein was substantially unaffected by the curing process, regardless of weather. Hays in which the curing process was completed by mow drying were significantly higher in carotene at time of storage than those completely cured in the field. Changes in composition during storage were considerably greater than those which took place in the field after cutting. The significant changes in storage were an increase in fiber, and a decrease in N-free extract, sugar, and carotene, the losses of carotene being very high. Most of these changes during storage took place in the first month, a large part of them during the first week of storage. Losses of N-free extract, sugars and carotene during storage were significantly correlated with moisture content of the hays at time of storage. This was true for carotene regardless of method of curing. In barn-dried hays the correlation of losses in N-free extract and sugars with moisture content was not significant; it was significant for field-dried hays. Although barn-cured hays had a higher content of carotene than field-cured hays when stored, this advantage had disappeared almost entirely by the time the hays were fed out. Feeding trials for milk production with the two kinds of hay gave identical results in fat-corrected milk yield per pound of dry matter consumed. Some illustrations are given of how easily good hay can be spoiled by an indifferent job of curing, especially barn-curing. None of the constituents determined, with the possible exception of fiber, offers any promise as an indicator of the nutritive value of hay. The search for such an indicator will be continued.