Document zQDpkbjmrb2mEwymRavOVpbMg

132 CHAPTER ^ C 1965 Guide And DarfcrBook pbysiologlcal Factors in Drying and Storing Farm Oops f-i; rates for non-linear airflow systems, has been developed by Ives etai.l,: s' - DRYING OF SPECIFIC CROPS Hay - .v Forage crops may be harvested, dried; and stored Whay, or Harvested and stored under anaerobic conditions as gras silage. Hay quality can be judged by its color, leafiness,' and general appearance. Laboratory tests'and feeding trials give a more detailed picture of hay quality. The traditional method of 'm'ulring hay is to mow the forage and allow it to field cure or dry in the swath''ahd windrow/but, with the advent of 'readily, available'electricity, mechanically operated blowers have been used to dry the hay in the bam or chow. ' Because forages,'principally alfalfa, have high'vitamin con- .tent, dehydrated ahd'groiihd alfalfa is of particular interest'to feed manufacturers: Alfalfa meal -supplies provitamin A (carotene), vitamin E, xanthophylls (poultry pigmenting fac- toreX'vitaihin K, vitamin C, and B-vitamihs. * . figs. 5 through 10 are the results of'careful studies ini the evaluation of the several methodsof harvesting hay.1* The 'study was conducted at Beltsville, Maryland. As shown in Fig/9, the rapid loss of carotene' immediately after the forage is cut indicates the need for rapid transport to the dehydrator when alfalfa meal with high vitamin content is desired. i II ackocuwtti urn ' pn Tl tl ato . ooitokatco Rg.`5:':.'.Pereentageof Dry' Matter Lost in Reid'and v/.During Storage and Percentage Preserved for Feeding.) .' (M - p I mjo ; corroatfO -RCLOCUKBWtr' Unas'` DssS 1 .fig. 6 -. Percentage of- Protein Lost in field qnd During Storage and PCrcentage PreseiVed for Feeding pjg 7 .... Percentage of N-Free Extract Lost in field and During Storage and Percentage Preserved for Feeding 'Several factors may influence the' retention of the vitamins during storage of dehydrated forages,' such' ;as the1 starting plant material,' conditions of dehydration, addition of stabilixers, and conditions of storage. Low temperature reduces the .rate of loss. Inert gas atmosphere in storage also-reduces losses/'as'shown by: Hoffman' and others." According to Thompson etal,n blanching of fresh alfalfa before drying does hot alter the storage stability of carotene. Table 4 shows the results of their tests'on the effect of prolonged heating at 212 F. "Hie - alfalfa was dried after three quarters of an hour; beating'beyond this time represented excessive exposure'to tliis temperature. They considered carotene retention in the intact meal at':149 F storage.temperature a measure of 'storage stability/ Table 5 shows the effects of underdryihg and overdrying on carotene stability, also determined by Thomp son et qL They determined that: normal material is considered to be a product that contains from 8 to 9 percent moisture after grinding, underdried material contains from 10 to IB percent, and overdried material contains less than 6 percent moisture. Grain The physiological factors involved in diying and storing grain are somewhat different from those applying to forages. Grain.is the end product of plant growth and most physio logical activity within the grain or seed is approaching a low leveL- With forage, the biological activity within the plant is at or near its peak at time of harvest. . Grain must be stored dry, to prevent destruction by micro-, organisms. There are two major considerations in the storage of grain, (1) the time grain ran be held at harvest moisture content before damage by. microorganisms will take place, and (2) the upper temperature limits of the diying air which will dry.the crop without'causing physical damage to the grain in terms of its ultimate use. Shelled Com / Shelled field com is used .primarily, as livestock feed. How ever, some of it is used by. the milling or processing industries in the production of com starch, com oil, and other products. This com can be severely damaged by mechanical drying if drying air temperatures exceed 150 F. The structure of the cell walls is changed by higher temperatures, making separa tion of gluten from the starch very difficult. -' There is very tittle information on the relationship between the drying method and the feed value of com. Market grade, as established by the Agricultural Marketing Service of the USDA, is the primary criterion for evaluating com value. Some investigation h* been made on the effect of drying air temperature oh the nutritive value of com as feed for rats.. According to .Cabell et al,B it appears in these tests that B9 to SS percent moisture shelled com can be dried tvithout loss of Storage and Percentage Preserved-for Feeding-- , Rg. 10.... Relation Between Time in Swath and Windrow and Reid Losses of Ether Extract, Ash, N-Ffee Extract,^ and Crude fiber.,..