Influence of the age of first insemination and first calving in Holstein – Friesian heifers on farm economic efficiency

Abstract

Abstract. The present study aims to assess the influence of the age of first insemination and first calving in Holstein-Friesian heifers on the cost of breeding and the cost of their marketing as breeding animals. For this purpose, a study was conducted on 7 farms (A, B, C, D, E, F, G) situated in Central and Southern Bulgaria in which Holstein-Friesian cattle are bred. The results of the study indicated that the age of first insemination in the controlled farms was 17.2 months on average, and the age of first calving (AFC) was 26.6 months, which was within the established norms for the Holstein-Frisian breed raised in the country. The heifers from farm A, which entered breeding age the earliest (at 16 months), as well as the age of first calving (25.3 months) had the longest utilisation period – 4.9 lactations. However, they did not develop the highest milk yield either and the economic performance from their raising was low. The heifers on farm F, with age of first insemination of 17.3 months, and first calving age of 26.8 months, and the ones from farm G, with ages 17.4 and 26.6 months, respectively, developed maximum milk yield per lactation. The expenses for raising a heifer of the Holstein-Frisian breed varied from BGN 1922 up to BGN 2389, with an average sum of cost for the studied farms amounting to BGN 2123. This indicated that the raising of heifers from a high-yield breed was an expensive undertaking, but when taking the necessary care for their breeding at a younger age during the period of use they developed higher milk productivity.