Milk production and anatomical udder capacity changes of udder halves subjected to increased milking frequency at two stages of lactation.

This study aimed to characterize the effects of increased milking frequency (IMF) at early and mid-lactation on milk yield and its association with changes in cistern and alveolar capacity. Fourteen multiparous Holstein cows were subjected to IMF using the unilateral frequent milking method from 3 to 24 d in milk (DIM). At mid-lactation, cows were randomly assigned to one of 2 treatments, Control (C) or Repeated (R). From 150 to 170 DIM, IMF treatment was re-imposed in the R group. During IMF, left udder halves were milked 2 × and right udder halves were milked 4 × . To separate individual milk yields of udder halves, separate buckets were used to collect samples from each udder half. Milk samples and milk yield from right and left udder halves were collected on d 150, 170, 200, 230, 260, and 290 of lactation. Alveolar and cistern capacity were measured 26 h after the last milking at 140 and 172 DIM using an oxytocin inhibitor. Cistern and alveolar capacity were measured by evaluating the milk harvested after oxytocin inhibitor and oxytocin administration, respectively. Udder half difference yields were calculated by subtracting left half yield from right half yield. At 170 DIM, the udder half difference in R was 2.27 kg greater than the udder half difference in C. Udder halves milked 4 × produced more milk and protein than 2 × udder halves in the R group at 170, 200, 230, and 260 DIM. Cumulative (150 to 290 DIM) and carry over (200 to 290 DIM) udder half differences in milk yield were similar between the C and R treatments. Alveolar volume was similar between udder halves milked 2 × or 4 × at 140 DIM, while cistern volume was larger for udder halves milked 4 × than 2 × in early lactation. There was no difference between alveolar or cistern volume proportion in udder halves milked 2 × or 4 × before mid-lactation IMF. After 20 d IMF for the R group, alveolar volume was similar between C and R independent of udder half milking frequency. However, R held 4.9 kg more cistern milk than C. Control treatment udder halves had a greater alveolar proportion than repeated treatment udder halves. As expected, the cistern proportion was smaller in C and larger in R after mid-lactation IMF. IMF at early and mid-lactation enhances milk and protein yield largely during differential milking frequency regimens. The lack of enhancement in milk yield after IMF might be associated with a different response to IMF in the mammary gland at early vs. mid-lactation. Based on our results, we conclude that udder halves subjected to early and mid-lactation IMF had increased cistern volume capacity.The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Citation

G Perez-Hernandez, H H Hanling, H H Schramm, A J Lengi, B A Corl. Milk production and anatomical udder capacity changes of udder halves subjected to increased milking frequency at two stages of lactation. Journal of dairy science. 2023 Aug 23

PMID: 37641323

search → result