Assessment of Friesian Cattle Performance Sustainability Through the Evaluation of Phenotypic and Genetic Parameters and Trends of some Economic Traits Under Egyptian Conditions

Total of 3380 records from 1635 Friesian cows kept in Sakha and El Karada farms between 1988 and 2020 were utilized to measure their sustainability in performance by estimating the genetic and phenotypic parameters and trends for 305-day milk yield (MY), calving interval (CI), and age at first calving (AFC) . Fixed effects are farm, year of calving – season, and animal parity. The VCE program was used to estimate variance components and genetic parameters. The MY, CI and AFC averages were 3280 kg, 15 mo and 32 mo and their heritability estimates were 0.20, 0.07 and 0.34, respectively. Genetic and phenotypic correlations among the traits ranged from 0.03 to 0.05 and from -0.04 to 0.04, respectively. The corresponding genetic (GT) and phenotypic trends for the studied traits showed deterioration in the overall rates and the ranges of breeding values were from -57 to +105 kg, -0.15 to + 0.25 mo and -0.35 to +0.30 mo for MY, CI and AFC, respectively. Strong intervention in selection and management powers may alter defects by using modern reproductive techniques in breeding programs for future generations. The farm's financial aspects were disturbed by delaying AFC or extending CI. The low CI produced more profit for the farm but prolonging it even for one day caused a financial loss. Also, as AFC expanded, MY increased, but overall farm profits decreased due to the high cost of rearing and replacements after AFC of 24 months