Johanna Ahmann

Mrs. Johanna Ahmann

University of Bonn, Institute of Agricultural Engineering
orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 December 2021 in Animals
Verified
Journal Article
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JAJohanna Ahmann
Johanna Ahmann
Julia Steinhoff-WagnerJulia Steinhoff-Wagner
Julia Steinhoff-Wagner
Wolfgang BuescherWolfgang Buescher
Wolfgang Buescher
The immunoglobulin concentration in bovine colostrum should be measured to ensure feeding with sufficient immunoglobulins (≥50 mg immunoglobulin G mL−1). Adequate feeding prevents diseases, promotes development, and has a positive influence on the adult animal. Indirect and direct measurement methods are available for this purpose. Direct measurement methods cannot be easily used in practice; therefore, farmers use indirect methods such as a colostrometer and a refractometer. Many factors influence the immunoglobulin concentration of colostrum; some of them have already been intensively researched. In particular, lactation and temporal aspects play an essential role. Newer aspects such as dry period, seasonal influences, and genetics are gaining importance, but their impact on immunoglobulin content has not been sufficiently investigated. Developments are still needed, especially in data management. This review analyzes the outcome of different studies on the indirect and direct measurement methods and discusses different factors influencing the immunoglobulin concentration of bovine colostrum.

1 November 2024 in Journal of Dairy Science
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Journal Article
Open access
JAJohanna Ahmann
Johanna Ahmann
JFJana Friederichs
Jana Friederichs
Wolfgang BuescherWolfgang Buescher
Wolfgang Buescher
Julia Steinhoff-WagnerJulia Steinhoff-Wagner
Julia Steinhoff-Wagner
Because calves are born with low levels of antibodies, effective colostrum management is one of the most critical factors for successful calf rearing. A timely and adequate supply of sufficiently high-quality colostrum immediately after birth is essential to ensure the passive immunization of calves. Frozen colostrum reserves are recommended to fulfill the immunological and nutrient requirements of newborn calves, even in exceptional situations; however, the implementation rates on German dairy farms and challenges of realization remain unclear. A 33-question online survey, focused on frozen colostrum reserves, was developed to obtain an overview of colostrum management practices on German dairy farms. The questionnaire was divided into 3 sections: 1. personal data; 2. farm characteristics; 3. colostrum management. Of the 155 responses we received, 63.9% were from female farmers, and 35.5% were from male farmers. Conventional farming was practiced on 89.0% of farms, and organic farming was practiced on 7.1% of farms. Of the respondents, 89.0% froze colostrum. The main reasons for freezing colostrum were: 1. the dam does not produce enough colostrum; 2. the dam cannot be milked; or 3. in cases where the dam dies during birth. Farmers primarily froze colostrum from cows during their third to fifth lactation. Before freezing, 33.1% of the respondents measured indicators in the colostrum to estimate Ig concentrations, whereas 2.3% determined the colostrum quality after freezing. Reusable and disposable PET deposits (23.1%, 22.3%) and ColostroBags (20.0%) were the primary containers used to freeze colostrum. The main reasons for not freezing colostrum were the high labor intensity and the availability of fresh colostrum from other cows. Thawing methods included buckets (47.7%) and professional water baths (13.8%). The survey identified areas in which improved knowledge transfer could enhance colostrum management. Furthermore, there appeared to be a lack of specific, feasible instructions for employees concerning the practical implementation of colostrum management. Most importantly, the regular determination and documentation of Ig concentrations should be emphasized. The added value of stored colostrum, relative to a greater workload, should also be promoted, particularly on smaller farms.

30 June 2023 in veterinär spiegel
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Journal Article
Closed access
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JAJohanna Ahmann
Johanna Ahmann
JSJulia Steinhoff-Wagner
Julia Steinhoff-Wagner
WBWolfgang Büscher
Wolfgang Büscher
Die Kälbergesundheit als wichtiger Schlüsselfaktor für eine anschließende erfolgreiche Milchviehhaltung basiert insbesondere auf einem optimierten Kolostrummanagement. Lesen Sie, auf welche Faktoren es hierbei ankommt und wie sie positiv beeinflusst werden können. Article published online: 30 June 2023 © 2023. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany