Longevity of Purebred and Triple-Cross Dairy Cows in Entre Rios, Argentina

This study evaluated animal longevity according to age at first calving of pure and triple-cross dairy cows in an establishment in Entre Ríos, Argentina. Retrospective data from 1.498 dairy cows between 2012 and 2021 were analyzed, belonging to a commercial establishment in the center-west of Entre Ríos province, Argentina. Analyzed cows were those discarded (due to sale or death) and with records of their entire productive life. They belonged to five different racial groups, pure Holstein (H), pure Jersey (J) and triple crosses, resulting from the insemination of Holstein x Jersey (F1) cross cows with semen from bulls of the Brown Swiss (P), Guernsey (G) and Montbeliarde (M) breeds, respectively. The cows were grouped into three levels (CAT), according to age at first calving. These categories were: CAT1: < 24 months; CAT2: 24 ≤ CAT2 ≤ 30 months and CAT3: > 30 months. Significant differences were found in survival curves of the productive life variable (p=0.0001) at 50% survival probability. Jersey cows had the lowest longevity (60.4 months) and showed significant differences with Guernsey (72.7 months), Holstein (65.8 months) and Montbeliarde (70 months). Brown Swiss cows (86 months) had the highest longevity compared to the rest (CAT was not considered). In CAT1, Brown Swiss showed significant differences from the rest (p<0.05). In CAT2, Brown Swiss showed significant differences (p<0.05), as J when compared with Guernsey. In CAT3, only Brown Swiss showed significant differences (p<0.05) compared to Guernsey, Jersey and Montbeliarde. Triple-cross Brown Swiss dairy cows had greater longevity. Those having their first calving at a later age showed higher longevity, both in comparison with other genotypes and among the Brown Swiss cows. Highlights: Triple-cross Brown Swiss (P) dairy cows demonstrated the highest longevity (86 months), significantly outperforming all other tested genotypes, including purebred Holstein and Jersey cows. Crossbred cows exhibited longer productive lifespans compared to purebred cows, suggesting crossbreeding is a relevant strategy to improve cow longevity and reduce replacement rates in grazing systems. Age at first calving is a significant factor in cow longevity. Triple-cross Brown Swiss cows that calved at an older age (CAT3: >30 months) showed the greatest longevity compared to other genotypes and the Brown Swiss in younger categories. Longevity differences among genotypes were statistically significant across survival curves at 50% survival probability ($p=0.0001$), emphasizing genetic and management factors on productive lifespan.