| dc.description.abstract | The aim of this study was to Measure the genetic impacts on 305 day Lactation production
and performance by crossbreeding with Holstein-Friesian from cows with different
proportions of Holstein-Friesian genes, obtained from the Serbian Fleckvieh (SF) and the
Holstein-Friesian (HF) crossbreeding program in Vojvodina. The upgrading of local breeds
with the Holstein-Friesian breed in Vojvodina started in 1971 and continued until 2008. Six
genotypes of cows (F1, R1, R2, R3, R4, R5) were obtained with increasing percentage of Holstein
genes, in order to attain purebred Holstein cows. Of all obtained genotypes, cows of
genotype R5 with a proportion of Holstein genes from 98.44 % had the highest 305 day
Lactation milk production (5801kg), followed by cows R4 with 5760 kg (96.87 % HF genes)
and cows R3 with 5712 kg (93.75 % HF genes). Finally the process of upgrading resulted in
pure Holsteins with 5752 kg of milk. The 305 day Lactation production of milk fat did not
show statistically significant difference (P>0.05) among the genotypes R1 – R5 which ranged
from 46 to 60 kg. The pure Holstein cow obtained after six intermediate generations had the
average 305 day Lactation milk fat production of 201 kg. With the increase in the proportion
of Holstein-Friesian genes, the percentage of milk fat was decreased, so that the cows of
genotypes R3, R4, R5 and pure Holsteins, had less than 3.5 % milk fat. | en |
