Milkability traits across milk flow curve types in Sarda sheep

A temporary interruption of the milk flow is observed between alveolar and cisternal fraction in ewes for the peculiar anatomy of the mammary gland. Often during milking a physiological delay in milk excretion between the cisternal and the alveolar fraction occurs. However, long delays may indicate suboptimal pre-stimulation of teats and/or insufficient oxytocin release in the bloodstream, resulting in undesired protracted interruptions between the 2 milk peaks. Moreover, a clear distinction between the fractions may be undetectable in high-producing ewes, particularly in early lactation. Based on both milk flow curve shape and duration of different excretion phases during milking, 3 curve types can be identified: single-peak (P1), double-peak (P2), and long plateau (PL). The aim of the present study was to compare milkability traits across the 3 milk flow curve types using data recorded in Sarda sheep breed; for this scope, 10 features were measured with a milkmeter in 568 ewes belonging to different parities, lactation stages, and commercial farms. After editing, data of 544 ewes reared in 17 farms were available for the analysis. The P1 curves were the most frequent (57.5 %), but ewes with a PL curve were significantly more productive than those with a P1 curve (0.61 ± 0.03 vs 0.53 ± 0.02 kg of milk/milking). Milk yield of P2 ewes was intermediate (0.58 ± 0.03 kg of milk/milking) and in all curves the majority of milk was excreted in the first 60 s of milking. The highest milk flow rate and the shortest milk emission time were estimated for the P1 curves; moreover, the blind time, indicator of overmilking, was the minimum in PL curves and the maximum in P1 curves. Based on such findings, farmers are recommended to pay more attention to milk emission curves in their herd in order to avoid overmilking, particularly in the presence of P1 curves. Considering the large herd size of Sarda breed farms (170.3 ewes per farm in 2020), part of milking routine could be slightly modified and customized according to milk flow curve type and lactation stage. Ideally, this will allow optimal milking practices to be adopted within groups of ewes with similar milkability. Monitoring milk emission curves and adopting less-standard and more adjusted milking practices is useful to meet the ewe's individual milking ability and in the long term would limit mammary gland stress, reduce antimicrobial use due to udder issues, and improve the udder health in Sarda sheep.