|Jung, Hans Joachim|
|Payne, Arthur - FORMER ARS EMPLOYEE|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 19, 1996
Publication Date: N/A
Interpretive Summary: Limited digestibility of forage crops is a major impediment to milk production by dairy cattle. A component of forages known as lignin is thought to be the primary factor that limits forage digestibility. Unfortunately, the measurement of lignin concentration of forages is difficult, and there are several methods of lignin measurement that give very different estimates for lignin concentration of the same forage sample. Our study was designed to determine if two of the major lignin measurement methods were similarly related to forage digestibility. An examination of 36 forages indicated that although the two lignin methods gave different estimates of lignin concentration, both lignin methods were equally related to digestibility of the forages. This means that although these lignin methods may not agree on how much lignin is present in a forage sample, either lignin method can be used to predict the digestibility of the forage. This information will be useful to animal nutritionists as they evaluate forages and formulate dairy cow diets.
Technical Abstract: The acid detergent lignin and Klason lignin methods were compared for their correlation with digestibility of forages. Thirty-six forages, including C3 legumes and C3 and C4 grasses, were analyzed for sulfuric acid detergent lignin, Klason lignin, and in vitro digestibility of dry matter and neutral detergent fiber. Twenty of these forages were also fed to sheep at restricted intake for measurement of dry matter and neutral detergent fibe digestibilities. Lignin concentrations determined by the two lignin methods were positively correlated and the Klason lignin value was always greater than the acid detergent lignin concentration, with the largest differences being observed for grass forages. Digestibilities of forage dry matter and neutral detergent fiber were negatively correlated with both lignin methods for the in vitro system and the sheep digestibility trials. The degree of correlation for the two lignin methods with digestibility was sgenerally similar across all forages and within forage classes. Slopes of linear regressions of digestibility on lignin concentration did not differ between legumes and grasses. Although the sulfuric acid detergent lignin and Klason lignin procedures give very different estimates of forage lignin concentration, it appears that they are similarly correlated with digestibility and should yield predictions of forage digestibility of similar accuracy.