Welcome back to our second discussion in the Herd health section. I'm Dr. Robert Van Saun and today we'll be discussing the single most significant time in a cows life cycle in its relationship to disease. Today's objectives are to learn the normal stages of calving, followed by an understanding of how to properly intervene when necessary. The time of calving is the final culmination in the nine month reproductive process. Goals of any farm relative to working with a calving cow are shown here. The calving process is the single, most challenging time for the cow from a health and production perspective. As was discussed in the pre-part of nutritional management discussion with Dr. Vargo, the late, pregnant cow must undergo significant metabolic adjustments to initiate lactation leading to increased risk for a variety of metabolic and infectious diseases. This is in addition to the physical challenge of delivering a 90 to 95 pound calf for a Holstein cow. Calving occurs over a period of time ranging from 3 to more than 24 hours depending upon cow age. This listing shows the three stages of calving. The normal time frame for Stage 1 is between 2 to 6 hours. Stage 2, 1 to 2 hours, possibly 3 with heifers. And 1 to 8 hours for Stage 3. Stage 1 is essentially the process of preparing the birth canal in positioning the calf for proper delivery. Ligaments around the pelvic area will loosen, thus allowing more give to deliver the calf. Other physical signs include swelling of the vulva and plumping of the teats as they fill with colostrum. Cows will usually become restless and isolate themselves from others. One should observe these cows about every four hours to monitor progress. During this time, the first water sac will protrude out and regress, as it uses hydraulic pressure to expand that cervix and birth canal. It is important not to open the sac too early preventing its dilation actions. Stage 2 is the physical delivery of the calf through the birth canal. Ideally cows should be placed in individual maternity pens that are clean, dry and have good footing and restraint methods available should she need some intervention. Abdominal contractions will be obvious in addition to frequent uterine contractions to move that fetus through the canal. Cows will typically lie down to complete the birthing process. Calf delivery is completed when either the hips or shoulders are passed through the birth canal depending upon the presentation. Stage 3 of calving is the process where the placenta detaches from the uterine connections and is released. Now that we understand how a normal calving should proceed, how do we determine when to intervene? It is important to remember that cows can calve on their own very well and only occasionally will need help. We don't want to intervene too quickly as this will increase the risk for birth canal damage, greater contamination of the uterus and injury to that calf. Farm managers should work with their veterinarian to develop appropriate Standard Operating Procedures or SOP in defining steps any worker should complete in deciding when to intervene and how to assess and correct the situation. Here are three key indicators of when you should decide to examine or assist a cow. Listed here are three more criteria for deciding if you should intervene. A distressed calf will often appear with a yellow-brown stain due to premature release of meconium during birthing. Meconium is that first feces passed from the calf when born. A lack of oxygen during birthing results in contraction of that lower colon, thus passing the meconium and staining the calf. Potential causes of dystocia are shown here, the first two will have some limitations and options for corrections in often require cesarean surgery to deliver the calf. Some disease is such a uterine torsion or twisting, or hypocalcemia can be corrected and birthing allowed to continue. The one where some practice in understanding corrective measures is fetal malposition. This is where the fetus is not in a correct presentation to allow delivery. This might mean a head is back or one or two legs are flexed or any combinations of these. Cows attempting to deliver twins could be a real challenge in determining which legs belong to which calf. Okay, so, let's say the cow or heifer is taking too long in delivering the calf. What steps should we take to intervene appropriately? The first step in assessing a dystocia case is to properly restrain the cow to prevent injury to her, or assistance providers. Next, you want to tie the tail out of the way, but not to a solid object, such as the barn. Clean the perineum thoroughly and use clean sleeves to protect yourself and the cow. The next step is to insert your arm to perform a pelvic exam and reach the calf to determine position. The best way to determine a calf presentation, head or tail first, is to identify the proper body part. If not present, then one can use the legs to determine presentation. Front and hind limbs bend in different directions, moving from the hoof up the leg. Once you have determined the calf presentation, you will extend the two front or hind legs. To extend the legs, one will need to use obstetrical chains. Chains need to be applied correctly to prevent injury to the calf's leg during the pull. A single loop just above the hoof could traumatically remove the hoof or break a leg bone. A double half hit should be applied to distribute the tension along the leg. Once the chains are properly placed, gentle tension should be applied to move the calf into position. Once the calf is engaged in the pelvis, some assessment of fetal size, and ability to deliver the calf through the birth canal is made. Tension on the chains to pull the calf should be coordinated with the cow's uterine contraction. Once the legs are protruding, pull downward at a 45 degree angle to facilitate the natural contour of the birthing canal. If the pull is hard, one can alternate pulling on individual legs to help reduce the size of the shoulders as they pass through the pelvis. Similarly, one can twist the calf 45 degrees to take advantage of oblong nature of the pelvic opening. There is much more detail in becoming proficient in correcting fetal malposition. But, we cannot cover each situation here. I encourage you to work with your veterinarian, or other appropriate person to gain further instruction. Once the calf has been delivered, you should examine the cow to assess if there is a second calf or some injury or damage to the birth canal. One should also keep records on the calving process, termed the Dystocia Score, for all cows to identify problem cows or heifers. This is part of that record keeping process of preventative Herd health programs, as previously discussed. Potential disease issues that could occur at the time of calving, or immediately afterwards, are shown here. Uterine torsion is a twisting of the birth canal, preventing the calf from being passed through. This could be corrected manually in some cases. Or by proper rolling of the cow. In severe cases, a cesarean surgery may be necessary. In manipulating the calf within the birth canal, the uterus or vaginal vault might tear. And have excessive bleeding. One can fill a clean sleeve with ice and insert it into the birth canal to reduce inflammation and swelling until the veterinarian can assess the severity of trauma or bleeding. Another critical event requiring veterinary intervention is a uterine prolapse. This is where the uterus is pushed out of the birth canal and turns inside out. The uterus will need to be thoroughly cleaned and carefully replaced. Depending upon the duration and the difficulty of a calving, there may be secondary damage to nerves passing along the pelvis. This may result in muscle weakness, or inability to stand, or control of the hind legs. Musculoskeletal injuries may result from the cow falling due to poor footing, nerve damage or Hypocalcemia. One of the most significant metabolic diseases of dairy cattle is Hypocalcemia or what is commonly termed milk fever. This disease results from the cow's inability to replace the calcium loss via colostrum precipitating a critically low blood calcium concentration. Clinical milk fever cows will be down, cold and depressed. Older cows are more commonly affected typically just prior to calving through 72 hours postpartum. More recently, a condition term, sub-clinical Hypocalcemia has been defined as blood calcium concentration blood normal less then two millimoles per liter or less then eight milligrams per deciliter but above a concentration that would induce clinical signs. These cows will be weak and prone to slipping or falling. Hypocalcemia is considered a gateway disease as it is often associated with other diseases such as retained fetal membranes, uterine prolapse, mastitis and other metabolic diseases. Dietary prevention of Hypocalcemia has been intensively studied for more than 60 years. In spite of all of this research, disturbed calcium homeostasis remains a significant problem for calving cows. Two documented methods of altering the prepartum diet for at least 14 days prior to calving have been used to prevent Hypocalcemia. Calcium supplementation at the time of calving or immediately afterwards via boluses or drench has been used on many farms to minimize calcium related issues. In this session, we have covered much material addressing critical issues of the calving cow. Our objectives were related to understanding the normal and abnormal birthing process, and how to properly intervene. We further discussed potential disease consequences of the calving process and highlighted the importance of calcium homeostasis. To this point, we have ignored management of the newborn calf. This will be our next discussion session in this course section. [MUSIC]