Evaluation of some economic traits in Holstein dairy cattle under Egyptian conditions

The objectives of this study were to estimate heritability and breeding value for some economic traits and the impact of some environmental factors on these traits in Holstein dairy cattle in Egypt. The data of 10034 records for 3295 Holstein cows were studied during the period from 1998 to 2021 in El-Alamia farm which is belonging to Universal Company for Agricultural Development and Soil Reclamation and has a commercial dairy herd located at Nubaria region in the K 90 Alex - Cairo desert road. The traits under study were: Total milk yield (TMY, kg), 305-day milk yield (305-dMY, kg), Lactation length (LL, day), Dry period (DP, day), Days open (DO, day), Calving interval (CI, month) and Gestation length (GL, day). The results showed that all traits under study were significantly influenced by parity. Also, the calving year has a significant effect on the studied traits except for gestation length. In the same trend, the effect of calving season was significant in all traits except lactation length and gestation length. Heritability estimates were 0.265, 0.393, 0.488, 0.238, 0.12, 0.138 and 0.57 for TMY, 305-dMY, LL, DP, DO, CI and GL, respectively. Cow breeding values for TMY, 305-dMY, LL, DP, DO, CI and GL ranged from -957 to 2170.5 kg, from -2432.75 to 2713.75 kg, from -266.25 to 340 days, from -114 to 100.25, from -105.75 to 164 days, from -13.9 to 13.18 months and from -0.33 to 0.45 days, respectively. Dams breeding values ranged from -823.5 to 1364.25 kg, from -1076.75 to 1531.75 kg, from -139.75 to 186.5 days, from -79.75 to 46.5, from -58.25 to 82 days, from -8.23 to 8.63 months and from -0.28 to 0.53 days, respectively. Sires breeding values ranged from -1057.75 to 1082 kg, from -1458 to 1549.25 kg, from -219.25 to 292.75 days, from -79.5 to 85.25 days, from -75.5 to 89 days, from -8.7 to 7.08 months and from -0.58 to 0.60 days, respectively. In conclusion, heritability values for all traits under study were low to moderate except for gestation length was a high value, so the most useful way to improve the traits under the study would be by improving the management level. Also, an estimated cow's breeding value has a wide range than sires' or dams' breeding value revealing a higher genetic variance and a good chance of selecting superior cows.