Relationship between udder filling time, morphological characteristics, and milk production in female donkeys of the Northeastern ecotype
Mammary gland, Female donkey (Jennet), Morphophysiology, teats
The objective was to relate udder filling time with the morphophysiological characteristics of the udder and teats in female donkeys of the Northeastern ecotype.
Fourteen Northeastern ecotype female donkeys were used, aged between 3 and 7 years, with an average body weight of 185 ± 30 kg. The jennies were separated from their foals at 5 a.m., with udder filling intervals of 2, 3, and 4 hours. Before manual milking, measurements of the udder and teats were taken, followed by milking and weighing of the milk. The results were subjected to tests of normality, variance, and correlation.
There was an increase in udder filling time in the female donkeys, resulting in a higher volume of milk obtained and increased dimensions of the udder and teats (P<0.05), with an average milk production of 313 g at the 4-hour interval. Udder morphometry showed changes according to the filling time (2–4 hours), with the greatest percentage increase (4.5%) observed in udder length. Measurements of width, circumference, and depth showed increases of 2.6%, 2.0%, and 3.6%, respectively. As for teat morphometry, the greatest effect was on teat diameter, with a 9.7% increase (both right and left), while teat length and the distance between teats increased by 7.0% and 6.0%, respectively.
Although most morphometric variables showed correlation with milk production, only udder length, and teat length and diameter were significantly correlated with milk yield. It is concluded that, in female donkeys of the Northeastern ecotype, a 4-hour udder filling time allows for a greater volume of milk to be obtained. The moderate to strong correlations between udder and teat lengths and milk production suggest that these traits should be considered as selection criteria in genetic improvement programs.