Evaluation of factors associated with immunoglobulin, protein, fat and lactose concentrations in colostrum of dairy cows from Austria.

Background: Calves rely on the passive transfer with immunoglobulins derived from colostrum. Currently, there is a lack of knowledge on colostrum management practices and colostrum quality on small scale family-owned dairy farms in Austria. The objectives of this study were to describe factors that are associated with immunoglobulin, protein, fat and lactose concentrations in dairy cow colostrum from the federal state of Salzburg. Therefore, an online questionnaire was designed to gather information on general farm characteristics. Further, the farmers collected individual colostrum samples and completed a detailed accompanying questionnaire for each sample. Immunoglobulin levels were determined by using a Brix refractometer and protein, fat and lactose by standardized laboratory methods. Linear mixed effect models were built to test factors associated with colostrum immunoglobulin, fat, protein and lactose concentrations.

Results: In total, 1,050 colostrum samples from 72 dairy farms were collected. The number of calvings per year was distributed as follows: ≤10 calvings: 8.3% of the farms, 11 to 20: 31.9%, 21 to 30: 29.2%, 31 to 40: 15.3% and ≥ 41 calvings: 15.3%. Overall, the median Brix value was 22.0% (7.3-36.1%). The number of samples with good and poor-quality colostrum was 517 and 528, respectively. Cow-level factors significantly affecting colostrum Brix% were parity, calving season, ante partum colostrum leakage, time lag between parturition and colostrum collection. In total, a subset of 307 colostrum samples from 39 farms from pure-breed dual-purpose Simmental cows were further analysed for protein, fat and lactose concentration. The median concentration for fat was 5.1% (0.5-18.5%), protein 14.6% (4.2-27.5%) and lactose 2.3% (0.2-5.0%). The cow-level factors affecting protein concentration were similar to the factors influencing Brix%. Fat concentration was influenced by the time lag between calving and colostrum collection and by parity.

Conclusions: The present study confirmed the factors, which are currently known to have an impact on colostrum quality. This was the first large scale approach in the federal state of Salzburg to survey colostrum management including colostrum sample collection. The range of colostrum quality was wide (7.3% Brix to 36.1% Brix) therefore many calves will be at risk of receiving poor quality colostrum as defined by a Brix of ≤ 22%.