THE EFFECT OF PHYSICAL EFFICIENCY OF FIBER ON THE CONSUMPTION AND SELECTION OF COMPONENTS OF TMR RATION FOR LACTATING COWS

Abstract

Total mixed ration (TMR) consists of many different nutrients contained in feeds of various origins, of a certain amount and composition, mixed into one meal. This structure of the meal began to be used due to the ability of animals to choose parts of the meal during feeding, preferring smaller and more digestible particles. By using TMR meals, animals are limited in their ability to select food, especially hay and silage, which is very important in the process of digestion and breakdown of food. Physically effective fibers are important for the prevention of various health disorders, chewing activity, rumen fermentation, pH value of rumen content, and fat content in milk. To determine the degree of selection of individual fractions of the TMR ration through time intervals, it is necessary to carry out appropriate experimental tasks such as sampling and fractionation of the TMR ration and different chemical analyses of nutrients in the completely mixed ration. Based on the analysis, it can be determined how much the physical effectiveness of fibers affects the consumption and selection of certain components of the TMR. Although TMR is a complete meal, various analyses have determined that selectivity still occurs on the part of cows in the mid-lactation phase, which consumed the smallest, more digestible food particles to the greatest extent. The peNDF8mm content ranged from 12.92 to 25.99%, while the peNDF4mm content varied from 23.25 to 37.23% throughout the feeding period. Such a dynamics of nutrition 
showed that in the first hours of nutrition, the most concentrated part of the TMR meal is consumed, followed by hay and silage that encourages chewing and rumination of food. This way of consuming feeds is a consequence of uneven nutrition, after which there are changes in the conditions of digestion in the rumen. The analysis of the experimental TMR ration proved the voluminous character of the ration, which, based on the average length of the particles, was classified as a finely ground ration. In addition to the aforementioned analyses, for more precise assessments of the physical effectiveness of TMR rations, additional tests can be included, such as measuring the pH value in the rumen and measuring the content of various parameters of milk, especially milk fat.