Correlation between the milk ingredients in domestic spotted breed of cattle

Kvaliteta mlijeka najviše zavisi od količine proteina i masti koje se nalaze u njemu. Ove dvije komponente dalje utiču na suhu tvar i specifičnu težinu mlijeka. Laktoza kao energetska vrijednost ima daleko manji značaj u ishrani, a kod prerade mlijeka u sireve predstavlja čist tehnološki balast. Ranije tržište više je pokazivala ekonomski interes za mliječnu mast, pa su prerađivači nametnuli proizvođačima mlijeka i njegov otkup po procentu masti. Istina, postotak masti je pokazivao najbolju sigurnost da mlijeko nije patvoreno tj. da nije sipana voda odnosno obrana mast. Ova dva momenta su dalje uticala na dugogodišnji selekcijski rad u govedarstvu na povećanju masti u mlijeku, paralelno sa povećanjem i količina mlijeka. Selekcija nije poklanjala pažnju i sadržaju proteina u mlijeku, tako da oni stagniraju.An experiment has been carried out with 20 cows of Domestic Spotted breed in the course of the first three lactations aiming to determine the correlations between the milk ingredients. Milk control has been done once a month and the milking twice a day. The milk samples have been collected from every single cow and analyzed on butter fat, protein, dry matter and specific weight. The total number of analysis was 19.200. The following results are obtained: Correlations between protein and butter fat in accordance with milkings and lactations ranged from r = 0,009 to +0,079. These coefficients are not statistically significant. In other words there were no correlations found between protein and buttersfat content in milk. Therefore the present knowledge that concerns this problem should be corrected. Correlations between protein and dry matter content in accordance with the milkings and lactations is low and it is ranged from r = +0,172 to +0,307. These are highly statistically significant (P<0.01). Vice versa, the correlations between butter fat and dry matter content are high both, in accordance with milkings and lactations and are ranged from r = 0,671 to +0,793. These coefficients are, by all means highly statistically significant (P<0.01). Correlations between protein and specific weight of milk in accordance with milkings and lactations prove to be low, ranging from r = (+0,258 to +0,391. Coefficients are highly significant. Correlations between butter fat and specific weight is slightly negative and ranged from r = 0,104 to 0,346. These coefficients are significant (P<0.05) and highly significant (P<0.01). Correlations between dry matter content and specific weight of milk in accordance with milkings and lactations are low and ranged from r = 0,005 to +0,342. These coefficients for the first lactation are not significant, while for the next two lactations are highly significant (P