Comparative studies on milk production of cows of black and white dairy breed imported from east germany and of cows three breed crosses of the bulgarian simmental with ayrshire and holstein friesian breed
Rasilev, I.; Ivanov, M.; Simeonova, S.; Stoikov, P.
Zhivotnov"dni Nauki 23(6): 3-8
The purpose of the study was to carry out a comparative evaluation of milk production of genotypes 30 and 31 of the Black and White dairy breed (SMR) imported from GDR and of the three breed crosses of the Bulgarian Simmental cattle with the Ayrshire and the Holstein-Friesian breed (HF .times. F1) (A .times. BSC). The study was conducted with 60 calves of the two populations to be compared commencing at parturition and lasting until completion of first lactation, feeding and rearing conditions being equal. It was found that the animal of the two populations showed in early age similar growth abilities e. g. the 18 month old three breed crosses (group 1) attained 395.28 kg and the genotypes 30 and 31 (group 2) 390.81 kg body weight; on the second month after first calving their body weight was 469.22 and 459.28 kg respectively. Milk production of the compared two breed groups first calvers was high and practically the same. For the 305th day lactation period the average milk production of the first calvers of group 1 was 3876.47 kg, containing 3.96% fat and 3.33% protein and of the first calvers of group 2 3822.32 kg 4.11% and 3.27%, respectively. Group 2 first calvers milk had a higher fat content by 0.15% to that to group 1 (P < 0.05), but as regards the 4% fat corrected milk and butter fat as well as the other indexes of milk production i.e. physical milk production and proteins in milk differences between the groups proved mathematically nonsignificant (P < 0.05). The first calvers of group 1 were characterized by a morphologically more adequate udder constitution and exceeded group 2 first calvers in milking speed per min. - 1.790 to 1.604 kg, but in respect to first 3 min, milking speed, the difference between them was negligible - 89.81 to 89.47%; negligible was also the difference between the obtained milk from the forequarters and hindquarters of the udder - 43.23 and 42.92% respectively.