Physical characteristics of feeds and their relation to nutrient components and dry matter disappearance in sacco

Abstract Samples of alfalfa hay (AA), orchardgrass hay (OG), maize silage (CS), alfalfa silage (AS), 70 : 30 (w/w) cracked maize to OG (70G) and 70 : 30 (w/w) barley straw to AA (70S) were collected weekly during each period (six samples per period) of a 6 × 6 Latin square design experiment. The weekly feed samples were pooled within each period and chemically analyzed for protein, neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and acid detergent insoluble nitrogen (ADIN) content. Grinding resistance, defined as the weight of the dried, preground (to pass through a 5-mm screen) feed that could be ground to pass through a 1-mm screen within the first 10 s, was measured in five replicates. Density of the feeds ground to pass through either a 5-mm or 1-mm screen was also determined dry and after a 24 h soak at 37°C in McDougall's buffer. Significant correlation coefficients were noted among these parameters, with the highest being 0.90 between grinding resistance and ADF content of the feeds. The density and hydration capacity values of the feeds were significantly correlated with various chemical components. Therefore multiple regression equations were developed to estimate feed composition.