Estimates of (co)variance component and genetic parameters using multi-traits animal model, traits studied were lactation period (LP), total lactation milk yield (TMY), and days open (DO). In all lactations based on 4745 records of Egyptian buffaloes calved during the period from 1980 to 2014 at Mehallet Mousa Experimental farms of Animal Production Research Institute (APRI), Ministry of Agriculture. The  six mixed model used in the analysis included the non genetic effects of month and year of calving, parity, and the random effects of additive direct genetics, maternal effect, maternal permanent environmental and residual. Means for LP, TMY and Do were 220.632 d, 1445.26 kg and 184.34 d, respectively. The estimates of heritability in six models for LP, TMY and Do were ranged from (0.026±0.56 to 0.047±0.16), (0.15±0.57 to 0.021±0.15) and (0.02±0.020 to 0.020±0.13), respectively. While Estimates of maternal heritability was very low in six models for LP, TMY and DO and ranged from 0.055±0.026 to 0.18E-09±0.79E-05: 0.081±0.029 to 0.52E-09±0.13E-04; 0.053±0.01 to 0.83E-09±0.12E-04, respectively. The estimates of genetic correlations between LP and TMY in six models ranged from (0.53 to 0.84). Estimates of genetic correlation between DO and TMY in six models ranged from (-0.15 to 0.58).While the estimates of genetic correlation between LP and DO in six models ranged from (0.30 to 0.94). Corresponding estimates of phenotypic correlation among same traits fluctuated (0.17 to76). Thus, the influence of the maternal genetic effect for traits studied was lowest thereby no relative efficiency of improvement. Vice-versa, direct heritabilities for TMY and LP were efficiency, therefore considerable rate of genetic improvement these traits under investigation. Genetic betterment for LP following up improve each TMY and DO. The estimates of heritabilities were low for DO indicated that the major part of the variation in this trait was environmental and selection may not prove effective in bringing about genetic improvement. Therefore, preferable improving management can play a major role in this trait.