Associations between the time of conception and the shape of the lactation curve in early lactation in Norwegian dairy cattle.
Summary of "Associations between the time of conception and the shape of the lactation curve in early lactation in Norwegian dairy cattle."
ABSTRACT:
BACKGROUND:
This study was carried out to determine if an association exists between the shape of the lactation curve before it is influenced by the event of conception and the time from calving to conception in Norwegian dairy cattle. Lactation curves of Norwegian Red cows during 5 to 42 days in milk (DIM) were compared between cows conceiving between 43 and 93 DIM and cows conceiving after 93 DIM.
METHODS:
Data from 23,049 cows, represented by one lactation each, with 219,538 monthly test days were extracted from the Norwegian Dairy Herd Recording System, which represents 97% of all Norwegian dairy cows. Besides veterinary treatments, these records also included information on daily milk yield at monthly test days. The data were stratified by parity groups (1, 2, and 3 and higher) and time to conception periods (43-93 DIM and >93 DIM). The sample was selected using the following selection criteria: conception later than 42 DIM, calving season July to September, no records of veterinary treatment and the level of energy fed as concentrates between 8.69 and 12.83 MJ. The shape of the lactation curves were parameterized using a modified Wilmink-model in a mixed model analysis. Differences in the parameters of the lactation curves with different conception times were evaluated using confidence intervals.
RESULTS:
Lactations characterized by a low intercept and a steep slope before peak milk yield and a rapid decline after peak milk yield were associated with early conception across all parities. The peak milk yield was not associated with time of conception.
CONCLUSIONS:
A practical application of the study results is the use of the shape of the lactation curve as a proxy for the feeding strategy in future herd management. In this way groups of cows with impaired reproductive performance may be identified due to an unfavorable shape of the lactation curve. Monitoring lactation curves and adjusting the feeding strategy therefore may be useful for the improvement of reproductive performance at herd level.
Affiliation
Journal Details
This article was published in the following journal.
Name: Acta veterinaria Scandinavica
ISSN: 1751-0147
Pages: 5
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21299912
- DOI: http://dx.doi.org/10.1186/1751-0147-53-5
Medical and Biotech [MESH] Definitions
Area Under Curve
A statistical means of summarizing information from a series of measurements on one individual. It is frequently used in clinical pharmacology where the AUC from serum levels can be interpreted as the total uptake of whatever has been administered. As a plot of the concentration of a drug against time, after a single dose of medicine, producing a standard shape curve, it is a means of comparing the bioavailability of the same drug made by different companies. (From Winslade, Dictionary of Clinical Research, 1992)
Mental Health Associations
Voluntary organizations which support educational programs and research in psychiatry with the objective of the promotion of mental health. An early association in the United States was founded as the National Committee for Mental Hygiene in 1909, became the Mental Health Association in 1976 and later the National Mental Health Association in 1980. State and local mental health associations in this country are chartered by the national organization and affiliated with it.
Learning Curve
The course of learning of an individual or a group. It is a measure of performance plotted over time.
Posthumous Conception
Conception after the death of the male or female biological parent through techniques such as the use of gametes that have been stored during his or her lifetime or that were collected immediately after his or her death.
Pregnancy Rate
The ratio of the number of conceptions (CONCEPTION) including LIVE BIRTH; STILLBIRTH; and fetal losses, to the mean number of females of reproductive age in a population during a set time period.
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