What’s important to know about the defense system of newborn calves?
The first weeks of life are a critical period for young calves as the immune system needs to develop and adapt and a huge load of pathogens is just waiting for a way to enter a weakened host organism.
Post-partum the immune protection of calves mainly relies on the innate unspecific part of the immune system and the passive immunity via maternal colostrum. The own adaptive acquired immune system is just slowly developing and is completed around week 8 up to week 12. The passive immune protection lasts for approx. 8 weeks with continuous decreasing power. Considering also the period of the development of the calf´s own adaptive antibody production a gap appears, when the sum of active and passive immunity in newborns is weakest and a high risk of disease arises. This phenomenon usually occurs around week 4 to 8 of life (Fig.1). In this phase calves are often just resettled into group housing units.
What to know about colostrum?
Even if the intestinal barrier is already closed for Ig uptake, a continuous colostrum feeding still can have a positive influence on the development of the intestine (Playford, Macdonald and Johnson 2000).
For the classification of Ig supply in the calf, usually IgG levels - the most common Ig group of bovines - and /or total protein in blood serum can be detected. A blood IgG level of 10-15 g/l is known to have clear positive effects on the health status of calves. An ingestion of 150 to 200 g of IgG via colostrum within the first 24 hours post-partum is therefore recommended (Quigley and Drewry, 1998). For a practical on-farm test, colostrometer or refractometer allow to assess the IgG content in colostrum in a quick manner. In general colostrum containing levels above 50g Ig/l can be stated as good and useable for calf feeding (Sanftleben, 2003).
How to improve colostrum quality and supply?
The particular content of colostrum relies on several aspects. Only Colostrum from cows of the 3rd lactation or higher should be used in order to cover a wide range of antibodies. Volume of the first milking should not be too high – about 4.5l to 8l in order to keep the valuable substances in a concentrated volume (Knutzen et al., 2011 ; Sanftleben, 2003).
The dry period of the cow should at least be 62 days, milk should not flow before first milking and the latter should be as early as possible (9h after calving already 41% of original Ig content in colostrum is gone) (Knutzen et al., 2011). The diet in the transition period needs to be balanced and sufficient in nutrients in order to gain the highest amount of valuable nutrients in colostrum. Furthermore, vaccination management of cows needs to be considered. In general, the cow should gain a good health status before giving birth due to various reasons. In this matter it is worth noting that the cow on the one hand needs to manage her own defense system around birth (increased inflammatory processes can be detected in cows a.p. and p.p., (Gessner et al., 2013)). On the other hand the cow needs to provide good colostrum quality for her calf. In case of metabolic disorders and other health problems around birth, it becomes more stressful and challenging for the cows organism to manage those processes in an efficient way. Phytogenic feed additives can often provide benefits for the dairy cow in this critical phase.
In good managed dairy herds it is standard to freeze and store high quality colostrum in order to be prepared for newborn treatment.Within the first 2 hours after birth the calf should already receive sufficient amount of colostrum (2l for a 40kg calf) at a temperature of 39°C. After 24 hours the colostrum intake of a newborn calf should reach one-tenth of its body weight (Sanftleben, 2005). It goes without saying, that besides the right colostrum supply hygiene in the stable/pen, staff and equipment, general housing conditions etc. need to be well managed.
Economic interest?
Calves are the high performing animals of tomorrow! Nonetheless, still 5-15% of live born calves die within the first month (Kaske and Kunz, 2007). Thus, caring for a good management from birth onwards is the right investment in order to gain a valuable dairy cow or well growing fattening bull. In optimizing the newborn management and caring for healthy mothers with good colostrum quality, the risk and incidence of diseases can be reduced. Colostrum feeding does not only reduce mortality and morbidity in newborn calves, but also still lowers morbidity at six months age. Also performance of first lactation is higher in heifers which had a good colostrum supply post-partum (Eulenberger, 2010).
Additionally, the improved proliferation of intestinal cells sets the basic for a healthy and good working digestive tract, with increased nutrient absorption and improved weight development (Sanftleben, 2003).