Pelleting characteristics of fractionated sun-cured and dehydrated alfalfa grinds

A pilot scale pellet mill was used to produce pellets using ground alfalfa leaf and stem fractions. Both sun-cured and dehydrated alfalfa chops were used in the experiments. The moisture content of the sun-cured and dehydrated chops was 8.4% and 9.6% (w.b.), respectively. A stack of two square sieves with different opening sizes and a pan it-ere used to separate leaf and stein fractions. The leaf and stem fractions were further segregated into two sample lots and ground in a hammer mill using screen sizes of 3.20 and 1.98 mm (118 and 5/64 in.). The leaf and stem fractions from each sample lots of same grind sizes were combined to get five different samples with leaf contents ranging from 0% to 100%, in 25% increments. The moisture contents and temperatures of the samples were raised to 10% to 11% (w.b.) and 76degreesC, respectively, in a double chamber steam conditioner prior to the pelleting operation. The temperature of material was further raised to 95degreesC in the pellet mill due to the friction between its roller-die assembly. Average particle sizes of sample lots were determined. Temperatures and moisture contents of samples, after various pelleting stages, were recorded. High durability pellets were produced using fractionated sun-cured alfalfa, irrespective of grind size (except for 100% steins, which was low). Durability fluctuated between high and medium range for dehydrated alfalfa (except for 100% stems, which was low). Greener pellets were produced from dehydrated alfalfa, while harder pellets were produced from sun-cured alfalfa.