Spin age-dependent correlation between live weight and milk yield of cows

For a long time the domestic black-and-white cattle was systematically improved by adding the blood of the world’s best dairy breed – i.e. the Holstein breed. In 2002 a new Ural type of black-and-white breed was officially registered. In first heifers with live weight of less than 550 kg an average negative correlation of milk yield is observed, in the first heifers with live weight of 625 kg or more this correlation is low negative to an average positive. In cows a positive correlation between live weight and milk yield per lactation is noted, except for group of cows with a high live weight where this correlation is not established. It should be noted that along with an increase in live weight from 550 kg or less to a weight of 599 kg, the correlation between these signs decreased, but this correlation increased among the cows with a live weight of 600-624 kg. The correlation between live weight and milk quality parameters per lactations is also ambiguous and ranged from high positive (0.89, 1 lactation, weight up to 550 kg) to low negative (-0.19, 1 lactation, weight 625 kg or more) in terms of correlation between live weight and mass fraction of fat (MFF) in milk.