Fundamentals for separation of particles mixture of two components

Abstract

A convenience sample of 20 farms in the geographic bounds of the Parmigiano Reggiano cheese producing region of northern Italy were studied. All farms used a TMR feeding system consisting of all dry hay (primarily alfalfa and grass) diets and adhering to the specific limitations of feeds as described by the Parmigiano Reggiano cheese consortium. Farms were visited twice for a survey of general farm characteristics and feeding management practices and collection of feed intake and samples at 0, 8, and 24 h after feeding to measure particle size characteristics of TMR in the feed bunk at each time. Many farms added 1 to 10 L of water per cow to the TMR in an attempt to reduce sorting and enhance intake. Based on particle size analysis it appeared that cows were not sorting diets to any great degree either with or without added water. However, it is likely that adding water to the TMR enabled cows to eat faster, thereby producing less saliva per kilogram of feed, and helped to create a situation for more slug feeding in the warm summer months of this study when the water-added TMR heated due to molding several hours after feeding. There was a positive correlation (r = 0.41) between the amount of added water and the percentage of cows on a farm that had an inversion of milk fat and protein or low fat percentage. Farms using pelleted concentrates also had less milk fat (r = −0.41). Overall there appeared to be no advantage of adding water to reduce TMR sorting on these farms.