We have previously discussed the research that indicates that the average length of time that a mature cow is in stage 2 of calving is less than half an hour. The average length of time that a first calf two-year old is in stage 2 of labor is about an hour. Remember stage 2 of calving is considered the time from the first appearance of a water bag and ends when the calf is completely delivered. What happens if a cow or heifer is allowed to stay in labor for a much longer time?
Every baby calf has a certain degree of respiratory acidosis. Acidosis is the result of the deprivation of oxygen and the accumulation of carbon dioxide that results from the passage of the calf through the birth canal. The excess of carbon dioxide results in a build-up of lactic acid (therefore the acidosis.) In order to correct the lack of oxygen and the excess of carbon dioxide and its by-products, the healthy calf will pant vigorously shortly after birth. The panting will allow the calf to take in more oxygen and release more carbon dioxide and the blood gas concentrations soon return to normal. Some calves, if they have been subjected to a lengthy stage 2 of calving, may be sluggish and slow to begin this corrective process. Depending on the severity of the respiratory acidosis, total correction may take place too late to prevent some damage to key organs. Oxygen deprivation to the brain may result in what ranchers have termed “dummy” calves.
In moderate respiratory acidosis, the calf may be slow to rise to its feet and therefore slow to find the teat and nurse. Colostrum intake in the first 6 hours of life is critical to the disease defense of the calf and any delay in the intake of colostrum may reduce the amount of passive immunity that the calf receives from its mother. Compounding the problem is the ongoing acidosis. Research has shown that calves that are acidotic will be less able to absorb the antibodies that are contained in the colostrum even if it is ingested on time.
As we observe cows and especially first calf heifers in this fall calving season, it is to our economic advantage to save as many calves as possible. Providing timely assistance to a cow or heifer struggling with the delivery process can be important in getting the most possible calves to market next year at sale time.