INVESTIGATION OF SUPPLEMENTARY MILK CONCENTRATES IN LARGE-SCALE DAIRY-COW HERDS

Requirements and principles about the composition of the so-called supplementary milk concentrate are described. According to the authors' experience, large-scale dairy farms use supplementary concentrates of various composition. To investigate these, out of 59 large-scale units, a total of 61 samples of supplementary milk concentrates fed to a total of about 40,000 dairy cows were collected for analysis. Composition, dry matter, crude protein, crude fat and mineral element contents were determined in each sample. The main conclusions of the investigations are summarized as follows: In intensive large-scale dairy farms supplementary milk concentrates are composed primarily of feed wheat, corn meal, extracted sunflower meal and wheat bran (Table 1). Some 34.5% of the 55 concentrates of known composition contained only 2-3 components (Table 2). - The crude protein, crude fibre and mineral element content of them varied between wide ranges (Tables 3 and 5). - According to information given, common salt (NaCl) supplementation occurred only in 29% of the concentrates and in 11% of them no information whatsoever has been given about mineral element supplementation (Table 4). - The practically important Ca, P and Na content of the samples showed not only unusually wide variations, but their concentrations fell often short to the requirements of milk production (Table 5). Out of the microelements, in some samples the Zn content reached excess levels (more than 250 mg/kg) and the Cu content of other samples was very low (7 mg/kg) (Table 6). - Out of the toxic mineral elements Cd was present in average values of 0.27 mg/kg and Hg in 0.80 mg/kg. - Extreme variation in mineral element concentration can be explained by the great variation in the number and quality of the feed mix components as well as in some cases with unsufficient mineral element supplies. In favour of economic milk production, the authors suggest the more careful selection and combination of components in preparing supplementary milk concentrates and the incorporation of properly balanced mineral element mixtures.