Influence of udder type traits on stayability in the Italian Mediterranean buffalo

In previous studies, stayability has been found to be a useful tool to assess longevity in Mediterranean Italian Buffalo. Animal longevity has been shown to correlate with type traits in dairy cows and in dairy buffaloes, as long as milk production increases thanks to genetic selection. In buffaloes, morphology was found to influence stayability up to parity 7, after which milk production was the discriminating trait. A wide thorax, properly angulated and with a good diameter, together with a longer trunk, allows higher production without compromising the health status of the animal, leading to greater longevity. A correct rump conformation, wide in both fore and hindquarters and only slightly angulated, also allows greater longevity, probably due to its involvement in reproductive events. The aim of this study was to correlate longevity with the udder traits measured by ANASB for IMB. The ANASB dataset including 49,667 animals born between 2005 and 2018, with type trait evaluations carried out between 2010 and 2021 was used. Data preparation and all statistical analyses were performed using the R programming environment v.4.3.0 (R Core Team, 2023). The R package lme4 (Bates D, 2015) was used to run a mixed effects logistic regression model using the ’glmer’ function, including milk yield, all type traits for udder conformation included in the ANASB type trait evaluation, age at first calving as fixed effects, and the interaction of herd-year of evaluation-inspector as a random effect. The morphological traits that were found to have a significant influence on stayability, especially at parity 1 to 5, were mainly udder depth with an inverse relationship and mean ligament strength with a positive relationship. However, milk production was always the most important trait for culling.