Short communication: Variation in serum immunoglobulin G concentrations from birth to 112 days of age in Holstein calves fed a commercial colostrum replacer or maternal colostrum

Dam-calf contact rearing in Switzerland: Aspects of management and milking

Cow-calf contact (CCC) rearing is becoming an increasingly popular alternative to the common practice of early separation of cow and calf in dairy management. Milkability can be impaired in nursing cows, which contributes to the loss of machine milk yield caused by calf intake, especially in pure dam-calf contact (DCC) systems. The aims of this study were (1) to describe the current status quo of DCC rearing regarding management and milking and (2) to evaluate the effects of DCC (suckling and milking vs. milking alone) and the effects of different types of DCC on milkability parameters, teat condition, and behavior during milking on Swiss DCC farms. By means of 17 telephone interviews with DCC farmers, we collected data on DCC management, housing, separation and weaning processes, milking procedures and techniques, and perceived milkability problems. Subsequently, we collected data on 10 of the interviewed DCC farms (183 cows): 4 DCC farms with a whole-day contact (WDC) system, 3 farms with DCC before milking (CBM), and 3 farms with DCC after milking (CAM). Five farms on which calves had no contact with dams were chosen as reference farms (178 cows). Using a milk flow meter, the occurrence of ejection disorders, bimodality of the milk flow curve, machine milk yield, duration of the decline phase, and duration of prestimulation were measured. The average mouthpiece chamber vacuum during the main milking phase and hind leg activity during milking were measured using a pressure sensor and an accelerometer, respectively. After cluster removal, the teat condition was evaluated, and a stripping milk sample was taken for fat content analysis. The interview results revealed that 8 of the 17 farms surveyed had a WDC system, and 2 farms operated a daytime DCC system. Contact before milking was applied by 3 farms, and 3 farms allowed CAM. On one farm, calves had access to dams 3 times a day. A great diversity in cow-calf management was found. In the on-farm data collection, 20 milkings of a total of 701 milkings examined met the criteria for a clear ejection disorder, with 17 of these observations occurring on WDC farms and none on reference farms. The stripping milk fat content was lower in nursing cows, indicating a lower degree of udder emptying. Machine milk yield was higher in nursing CAM cows than in nursing WDC and CBM cows. Farm types did not differ regarding teat condition, hind leg activity, or the occurrence of bimodal milk flow curves. In conclusion, the large variation in individual management approaches to DCC rearing even within DCC types, such as calf housing or cow breeds, implies caution when interpreting results. Contact after milking may be the system most beneficial for some productivity parameters, but adequate calf supply must be ensured. Higher amounts of milk remaining in the udder after cluster removal indicate that nursing can affect milkability, but future research should consider the effects of udder filling before milking to better interpret the fat content of stripping milk.

Invited review: The importance of colostrum in the newborn dairy calf

It is critical that bovine maternal colostrum is fed to newborn calves during their first hours of life. Colostrum is the secretion a cow produces after mammary involution that is rich in various nutrients. In addition to the nutritive value for newborn calves, immunoglobulins are of interest due to their role in developing the naïve immune system of calves at birth. The process by which a calf acquires immunity via absorption of immunoglobulins is defined as passive immunity. When calves consume an adequate amount of immunoglobulins, they are classified as having successful passive immunity (SPI). In contrast, if they are deprived of adequate colostrum, they are considered to have had a failure of transfer of passive immunity (FPI). Transfer of passive immunity is assessed by measuring serum IgG concentrations at 24 to 48 h of age. The major factors that influence whether a calf has SPI or FPI are colostrum IgG concentration, quantity fed, and age of calf at colostrum feeding. Monitoring apparent efficiency of immunoglobulin absorption in calves is often recommended to evaluate overall colostrum management practices. Serum IgG analyses can be determined with direct (radial immunodiffusion) or indirect (refractometry) methods and used to assess SPI or FPI prevalence.