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The objective of this study was to investigate the factors that affect the quantity, quality, and calcium content of the first colostrum in Holstein Friesian cows, with special emphasis on composition and potency. It should be verify that the lactation number is the main influence factor and that the amount of colostrum is etiologic for the developing of puerperal paresis. Another aim was to obtain more detailed data on the relation between the quantity and quality of colostrum and explore the possibilities and limits of affecting it. An observational study was conducted from April 2012 to March 2013 at a commercial dairy farm (2177 Holstein Friesians, average annual milk priduction approx. 11,300 kg, fat content 3.9%, protein content 3.3%).
The quantity of the colostrum was determined within a half an hour after calving using a direct-tocan milking machine. The immunoglobulin concentration was estimated by refractometer and the calcium content was measured in an external laboratory. To determine calcium, phosphorus, nonesterified fatty acids (NEFA), and beta hydroxybutyrate (BHB), a blood sample was taken from the coccygeal vein on calving day and on one and seven days postpartum. To determine body condition, the back fat thickness was measured by ultrasound at drying off (6 weeks prepartum), at transfer to the preparatory group (2 weeks prepartum), one day postpartum, at transfer to the production groups (2 weeks postpartum), and 6 weeks postpartum. In addition, the daily milk production on milking days 1 to 7, the mean production on milking days 7, 14, 21, 28, 35, and 42, and the 100-day milk production were documented. Calving data (calf gender, number, weight, calving process, stillbirths) and lactation number, father of the cow, length of gestation, age at first calving, length of the dry period, fertility parameters of prelactation (days open, number of inseminations), and diseases during the dry period and up to 3 days postpartum were included in the analysis. A stepwise analysis of the data for correlations and influencing factors was conducted by means of variance analysis, correlation analysis, and multiple linear regression analysis. The average colostrum quantity was 5.6 kg with an immunoglobulin concentration of 65.6 g/l and a calcium concentration of 2,386 mg/l.
The analysis showed that there are a number of influencing factors that have an effect on the quantity of colostrum. However, only ¼ of the variability of the colostrum quantity could be explained using the influencing factors examined. The dominant effect of the lactation number that was assumed in the working hypothesis was not confirmed. Instead, the effect of the lactation number is attenuated by other, more potent factors. Strong factors were milk production in the following lactation period, diseases after calving, the length of the period from drying off to transfer to the preparatory group, the father of the cow (genetics), and the weight of the calf. There is no relation to the content of calcium in the blood. The amount of calcium is not etiologic for the appearance of hypocalcaemia or milk fever. Selective breeding for high milk production and using bulls whose daughters have high milk production can also breed for high colostrum quantities. In farms with good colostrum quality, the effect of dilution of immunoglobulins is not large enough to lead to a noticeable decline of the Ig concentration. Colostrum should therefore not be excluded because of its quantity. Heavier calves result in an increase in colostrum quantity. However, breeding for higher birth weight is not recommended due to the risks involved for calving. The most important influencing factors for colostrum quality are genetics and the colostrum quantity. While almost half of the variation can be explained by the influencing factors examined, there is little possibility of significantly improving the Ig concentration by individual factors such as the length of the dry period. The lowest Ig concentration in colostrum was found in second lactation cows, but the effect of the lactation number was not confirmed in the multiple regression analysis.
In well-managed farms, the colostrum quality in Holstein Friesians is very high.
The influencing factors can explain only 25% of the calcium concentration in colostrum. The mean milk quantity in the first week postpartum and body condition at drying off have the strongest correlation. Although the source for the calcium content in colostrum is the calcium content in serum, there is no significant correlation. The transport paths of calcium from blood to the alveolar cell of the udder and through the cell into the colostrum are very complex and not sufficiently understood. Relationships and interactions with other components of colostrum such as immunoglobulins must be investigated in more detail.