Evaluation of low molecular weight fractions and crude enzyme preparation from a Trichoderma enzyme complex on in vitro dry matter degradation and utilization of fibrous feeds, and, Influence of fall protein supplementation with a self-fed liquid supplement on performance of beef cows grazing native tallgrass-prairie in the Kansas Flint Hills.

摘要

Experiments were conducted to investigate the effect of separating the fibrolytic enzyme complex from Trichoderma reesei (Order, Hypocreales; Family, Hypocreaceae) by molecular weight of the components on subsequent digestion of six common feeds and two pure substrates. The crude enzyme preparation was filtered through membranes with a molecular weight cutoff of 5 kDa and 10 kDa. The feed treatments consisted of a non-treated control (buffer only), 5 kDa filtrate, 10 kDa filtrate, and crude enzyme preparation. The filtrates and crude enzyme preparation were diluted in 12.5 mM sodium citrate buffer. In vitro fermentation followed treatment of the feeds and two time-points (24 and 48 hours) were used to measure digestibility. Release of glucose and total monosaccharides were quantified following treatment of alfalfa hay and soybean hulls, and release of phenolic monomers was measured following a single 24-hour treatment incubation of alfalfa hay and wheat straw. The greatest relative effect for all substrates and response variables were with the 10 kDa filtrates and the crude enzyme preparation treatments.; Another experiment was conducted to evaluate the effect of providing a liquid, high-protein supplement during the fall grazing period on beef cow and calf performance. One hundred twenty-two multiparous, pregnant, spring-calving cows were assigned to supplementation treatments in a randomized complete block design. Twelve fall pastures were utilized providing four replications per treatment. Control cows received no fall supplementation and then were hand-fed a dry supplement (40% CP, as-fed basis) from 12/17 until calving. Fall supplemented cows were either allowed access to a liquid protein supplement (40% CP; as-fed basis) approximately 2 months before weaning until calving (fall supplementation from 8/14 to 12/17) or from weaning until calving (fall supplementation from 10/15 to 12/17). The provision of a self-fed liquid supplement to beef cows grazing poor quality forage resulted in body weight and body condition score gains during the period from weaning until the start of the winter grazing period. Those cows not receiving liquid protein supplementation during the fall had the ability to compensate for their earlier nutritive status during the pre-calving period when appropriately supplemented during the winter.