Abstract

SCHULTZ, M.E; CAPELLARI, A.  and  SANCHEZ, S.. Analysis of age at first calving on productive and reproductive performance in first-lactation Holstein cows in an intensive system in Argentina. Rev. vet. [online]. 2023, vol.34, n.2, pp.48-54. ISSN 1669-6840.  http://dx.doi.org/10.30972/vet.3427043.

This study examined the relationship between age at first calving and milk production in Holstein heifers within an intensive system in the dairy basin of Córdoba, Argentina. Retrospective data from 452 cows calving between 2016 and 2017, aged between 23 and 32 months, were collected. The results revealed a significant decrease in adjusted 305-day milk yield as age at first calving increased. Cows calving at 24 months yielded higher total milk production by the end of lactation compared to those calving at 31 and 32 months. A significant difference in daily milk yield during lactation was observed based on age at first calving, while no significant effect of calving year was found. Total daily milk yield was also influenced by age at first calving, with cows calving at 24 months exhibiting higher production compared to those calving at 32 months. The dry period, representing the days from drying off to the start of the subsequent lactation, was also influenced by age at first calving, with significant differences observed between cows calving at 23 and 31 months, as well as at 24 and 31 months. In terms of reproductive variables, a significant difference in the calving interval was found based on age at first calving. No significant interaction between age at first calving and calving year was identified for any of the analyzed variables. In conclusion, this study demonstrated that age at first calving has a significant impact on milk production in Holstein cows within an intensive system. The findings suggest that placing greater emphasis on achieving first calving between 23 and 25 months of age may enhance productive and reproductive efficiency in dairy farms.

Keywords : dairy cattle; data analysis; milk yield; days open.

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