O congelamento da dieta total não afeta a avaliação da homogeneidade

Abstract

It is not known whether the freezing of TMR (total mixed ration) samples alters their physical characteristics, to the point of modifying the assessment of diet homogeneity supplied in the bunk for lactating cows. In this sense, the objective was to evaluate if freezing and thawing process of TMR samples alters the particles physical characteristics and, consequently, the diet homogeneity, when sieved with Penn State particle separator. In the Dairy Cattle Sector (SEBOL) at Fazenda Experimental do Glória (FAMEV/UFU), two samples of TMR offered at eight points on the bunk were collected. Of the sixteen samples collected, half were sieved immediately after collect (in natura sieving), the remaining samples being frozen for 72 hours, thawed for 12 hours and sieved (post- freezing sieving). The procedure for collecting samples of the diet offered for in natura and post-freezing sieving was repeated nine times. The sieving was done using the particle separator composed of three Polypropylene PP fiber sieves, with holes of 19 mm, 8 mm and bottom. After sieving, the particles retained in each sieve were weighed and thus the particles percentage was calculated, as well as standard deviation and coefficient of variation in sieves of 8 mm and depth. The experimental design used was completely randomized (DIC) with repeated measures over time. The measured variables were compared using the paired t test, at a 5% probability level for type I error. It was concluded that freezing of TMR samples for three days at a temperature between -25°C and -18°C and thawing for 12 hours does not cause changes in their physical characteristics and in proportion of particles retained on the 19 mm, 8 sieves. mm and bottom, being possible to determine the coefficient of variation and identify flaws in the process of mixing the diet.