Abstract
Determining the optimal insemination moment for individual cows is complex, particularly when considering the effects of pregnancy on milk production. The effect of pregnancy on the absolute milk yield has already been reported in several studies. Currently, there is limited quantitative knowledge about the association between days post-conception (DPC) and lactation persistency, based on a lactation curve model, and, specifically, how persistency changes during pregnancy and relates to the days in milk at conception (DIMc). Understanding this association might provide valuable insights to determine the optimal insemination moment. This study, therefore, aimed to investigate the association between DPC and lactation persistency, with an additional focus on the influence of DIMc. Available milk production data from 2005 to 2022 were available for 23,908 cows from 87 herds located throughout the Netherlands and Belgium. Persistency was measured by a lactation curve characteristic decay, representing the time taken to halve milk production after peak yield. Decay was calculated for 8 DPC (0, 30, 60, 90, 120, 150, 180, and 210 d after DIMc) and served as the dependent variable. Independent variables included DPC, DIMc (≤60, 61-90, 91-120, 121-150, 151-180, 181-210, >210), parity group, DPC × parity group, DPC × DIMc, and variables from 30 d before DIMc as covariates. The results showed an increase in decay, which is to say, a decrease in persistency, during pregnancy for both parity groups, albeit in different ways. Specifically, from DPC 150 to DPC 210, multiparous cows showed a greater decline in persistency compared with primiparous cows. Furthermore, a later DIMc (cows conceiving later) was associated with higher persistency. Except for the early DIMc groups (DIMc <90), DIMc does not affect the change in persistency by gestation. The findings from this study contribute to a better understanding of how DPC and DIMc during lactation influence lactation persistency, enabling more informed decision-making by farmers who wish to take persistency into account in their reproduction management.
| Original language | English |
|---|---|
| Pages (from-to) | 5794-5804 |
| Number of pages | 11 |
| Journal | Journal of Dairy Science |
| Volume | 107 |
| Issue number | 8 |
| Early online date | 3 Apr 2024 |
| DOIs | |
| Publication status | Published - Aug 2024 |
Bibliographical note
Publisher Copyright:© 2024 American Dairy Science Association
Funding
We gratefully acknowledge the MmmooOgle program (Puurs, Belgium) and Bonifacius van Ranst for providing the data. The authors thank Jan van den Broek and Hans Vernooij for statistical advice (both of the Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands). Author Yongyan Chen is financially supported by the Oversea Study Program of the Guangzhou Elite Project (Guangzhou, China). Supplemental material for this article is available at https://github.com/Bovi-analytics/Chen-et-al-2023b. Because no human or animal subjects were used, this analysis did not require approval by an Institutional Animal Care and Use Committee or Institutional Review Board. The authors have not stated any conflicts of interest. Nonstandard abbreviations used:decay \u221230 = decay at 30 d before DIMc; DIMc = days in milk at conception; DPC = days post-conception; G1\u2013G7 = DIMc groups; IQR = interquartile range; peak yield \u221230 = peak yield and decay at 30 d before DIMc; P1 = primiparous cows; P2+ = multiparous cows; Ref = referent.
| Funders | Funder number |
|---|---|
| Faculty of Veterinary Medicine, Utrecht University | |
| Oversea Study Program of the Guangzhou Elite Project |
Keywords
- dairy
- days in milk at conception
- days post-conception
- lactation persistency