Zh. Gergovska, T. Angelova, D. Yordanova, Zh. Krastanov, Ch. Miteva
Abstract. The study comprises 37 cows of which 20 Holstein and 17 Brown Swiss cows. The rearing technology in both breeds is free rearing in individual cubicles for rest. Milking is two times in milking parlour. Cows are divided in three technological groups depending on the physiological state, respectively: dry cows, І-st – up to 120-150 th day and ІІ-d lactation period. Feeding is on the basis of whole ration mixture including maize silage, alfalfa haylage, concentrated fodder and vitamin and mineral additives. The body condition of cows has been recorded on a monthly basis by using a 5-score evaluation system, from 0 to 5 points, recorded with accuracy up to 0.5 points. In Brown cows average BCS at calving is 3 points, average BCS during lactation is 1.64 points. In Holstein cows average BCS at calving is 2.8 points and average BCS during lactation is 1.38 points. Heifers from both breeds have a bit lower BCS at calving (3.0 points) than older cows, but they have less loss of body condition during lactation – 1.66 points. With cows at ≥ ІІ-d lactation loss is more intensive as early as the first lactation month and till the lowest BCS they lose a total of 2.04 points. Holstein cows lose at the beginning of lactation more points (an average of 2.14) and reach lower BCS (1.05) compared to Brown Swiss ones in which these values are 1.85 an 1.20 points. BCS drops to the lowest value during lactation in cows from both breeds with poor body condition at calving (2 and 2.5 points). The smoothest are the changes in the body condition of cows that had reached BCS at calving 3.5 and 4 points.