[Reproductive capacity and milk production in cows of various cattle breeds as related to age at the ist calving].

The course of parturition, the ability to get in-calf, and milk production were studied in 348 first-calved cows, in 162 cows of the Bohemian Spotted breed, 88 cows of the Black-Pied Lowland breed, and 98 crossbreds of these two breeds divided into three categories according to the age at the first calving (from 21 to 23 months, 24 months, and from 25 to 29 months). There were only slight differences in the average calf birth weight between the cows of all the breeds calving for the first time before the age of 24 months and cows calving later (lower by 0.70 kg, 1.

[Conception ability of early mated heifers of Bohemiam spotted and black-pied lowland cattle and their crossbreeds].

The conception rate of heifers was studied in dependence on their age and body weight at the first mating. The trial included 163 heifers of the Bohemian Spotted breed, 72 heifers of the Black-Pied Lowland breed, and 101 crossbreds between these two breeds. The heifers of the Bohemian Spotted breed mated for the first time at the age of 12 months had a lower weight than required by the standard (336 kg -- standard requires 360 kg) and a lower weight than the heifers of the other breeds under study.