Milking frequency and effect of fill time on the production and conformation of the udder of female donkeys of the Nordestino ecotype

The present research aimed to assess the effect of milking frequency and the relationship between udder fill time and morphophysiological characteristics of udder and teats, as well as milk production by female donkeys of the Nordestino ecotype. A group of 15 female donkeys between 3 and 7 years old was employed. The study was split into two trials: The first assessed the effects of different udder fill times (2, 3, and 4 hours) on milk production and mammary morphometry, while the second analyzed the impact of milking frequency (once, twice, or three times a day) on milk production and somatic cell count (SCC). Trial 1 showed fill time of 4 h resulted in greater milk volume obtained (313 g), with a significant increase in udder length (4.5%), depth (3.6%), and teat diameter (9.7%) (P < 0.05). Most morphometric variables had a positive correlation with milk production, with the highest coefficients observed for udder and teat length. In trial 2, increasing milking frequency from one to three times a day led to an increase by up to 457% in milk production. SCC did not vary between treatments, which suggests increasing milking frequency did not compromise mammary health. It is concluded that udder fill time of 4 h and milking three times a day favor milk production in donkeys of the Nordestino ecotype. The moderate to strong correlations between morphometric characteristics and milk production suggest potential use of those parameters as criteria in genetic selection programs targeting donkey milk production.