Effects of first-lactation milk production and culling reasons on lifetime performance traits of Holstein cows culled from an intensive system in Egypt

Objective: This study investigates the effects of first-lactation milk production and culling reasons on the lifetime performance traits of Holstein cows culled from an intensive system in Egypt.Methods: Complete lactation records of 12209 for 4522 second-sixth parity cows culled during 2008-2019 were enrolled in this study.Results: Means of days in milk(DIM), lifetime total milk yield(LTMY), lifetime daily milk yield(LDMY), productive life(PL), longevity, number of services/conception(NSPC), days open(DO) and calving interval(CI) were 371 days, 30223 kg,13.5 kg, 38 months, 68 months, 3.6, 169 days and 437 days, respectively.The first-lactation milk production (FMY) affected all the lifetime performance traits significantly (p<0.0001).Cows that produced higher FMY had higher both LTMY and LDMY.Cows of FMY>12000 kg had the longest both PL and longevity.With the increase of FMY, the values of NSPC, DO and CI increased.Culling reasons significantly affected all lifetime performance traits (P<0.0001).Cows culled due to reproductive problems had the greatest longevity whereas those culled due to endemic diseases recorded the lowest.The highest LDMY was recorded by cows culled due to metabolic disorders while the highest LTMY was recorded by cows culled due to lameness.Cows culled as a result of reproductive problems, metabolic disorders or mastitis recorded higher values of NSPC, DO and CI than those culled due to other reasons.Conclusion: The higher the first-lactation milk production, the higher the productive performance and the lower the reproductive performance.The performance traits of culled cows A c c e p t e d A r t i c l e differed depending on the reason caused culling.Reasons for culling should be studied through their inter-relationships since one disorder may cause or support the occurrence of others.