Effect of stage of maturity and growth cycle on shearing force and cell wall chemical constituents of alfalfa stems

Lignin: characterization of a multifaceted crop component

Lignin is a plant component with important implications for various agricultural disciplines. It confers rigidity to cell walls, and is therefore associated with tolerance to abiotic and biotic stresses and the mechanical stability of plants. In animal nutrition, lignin is considered an antinutritive component of forages as it cannot be readily fermented by rumen microbes. In terms of energy yield from biomass, the role of lignin depends on the conversion process. It contains more gross energy than other cell wall components and therefore confers enhanced heat value in thermochemical processes such as direct combustion. Conversely, it negatively affects biological energy conversion processes such as bioethanol or biogas production, as it inhibits microbial fermentation of the cell wall. Lignin from crop residues plays an important role in the soil organic carbon cycling, as it constitutes a recalcitrant carbon pool affecting nutrient mineralization and carbon sequestration. Due to the significance of lignin in several agricultural disciplines, the modification of lignin content and composition by breeding is becoming increasingly important. Both mapping of quantitative trait loci and transgenic approaches have been adopted to modify lignin in crops. However, breeding goals must be defined considering the conflicting role of lignin in different agricultural disciplines.

Evaluation of a nonstarch polysaccharidase feed enzyme in dairy cow diets

The objective of this study was to evaluate a commercial feed enzyme product (Natugrain 33-L; BASF Corporation, Ludwigshafen, Germany) used mainly in poultry diets for use in ruminant diets. The product contained mainly beta-glucanase, xylanase, and endocellulase activities. The study was conducted as a double 3 x 3 Latin square design with six lactating dairy cows (84 +/- 12 DIM) to measure intake, chewing activities, total tract digestion, and milk production. An additional three cows fitted with ruminal cannulae were used to measure dietary effects on ruminal fermentation and in sacco digestion characteristics. Cows received a diet consisting of 45% forage containing 0, 1.22, or 3.67 L of enzyme product/tonne of total mixed ration (DM basis). Using a low or high concentration of enzyme supplementation increased feed intake, but total tract digestibility only increased with the low concentration of enzyme. As a result, intake of digestible nutrients was increased to a greater extent for cows fed the low concentration than for cows fed the high concentration. Because the cows used in this experiment were in positive energy balance, increased intake of digestible energy due to enzyme supplementation did not increase milk yield or milk component yield. Further research is necessary to determine the mechanism by which adding a fibrolytic enzyme mixture enhanced intake, but only increased feed digestion when used at a low level.