By Adrian A Barragan
As I mentioned in one of my previous articles, the transition period is one of, if not the, most challenging period for dairy cows during their production cycle. During this time, cows experience four main physiological challenges: a drop in dry matter intake, an increase in nutrient demands, immunosuppression, and systemic stress and inflammation (especially around calving). Therefore, the best approach to manage this group of animals is by addressing these challenges. If we think about the drop in intake and the increase in nutrient needs, the main negative effects are animals going into a negative energy balance (because they are using more nutrients than what they are consuming) and developing metabolic diseases such as ketosis and fatty liver. Now, we cannot decrease the nutrient demands that cows have at this time, but we can decrease the drop in dry matter intake through proper management. Although cows will experience some degree of immunosuppression during this time regardless of management, an exacerbated stressful and/or inflammatory response may magnify this immunosuppression, increasing the risk of cows developing diseases. The losses for dairy cows associated with diseases are well known, but on top of affecting the welfare of cows and economics of the farm, these conditions have a long-term effect on the productivity and fertility of cows, decreasing milk production and conception rates, and increasing culling of animals. By modulating stress and inflammation after calving, the risks of developing diseases and poor performance may be decreased.
The management practices for transition cows must be focused on maximizing dry matter intake and modulating stress and inflammation. To maximize dry matter intake, diet composition — especially fiber and energy concentrations —is one of the most critical factors. Dr. Robert Van Saun clearly explained in our previous articles some of the key aspects for formulating transition cow diets. Although diet composition is important, I would argue that what we do with that diet is equally important. We could have the best formulated diet with the best ingredients, but if cows do not have access to it, the diet composition would be irrelevant. During this period, cows should have access to fresh feed at least 23 hours a day, and only have no feed available while cleaning the feed bunk in between feed deliveries. There are two main practices that stimulate cows to go to the feed bunk and eat — feed push-ups and feed delivery frequency. It is recommended to push feed up every two to four hours, with more frequent push-ups (every 30 minutes) during the first two hours after fresh feed is delivered. With regard to feed delivery frequency, research has shown that when performed often, up to four times a day, this practice will stimulate cows to go to the feed bunk and eat. However, feeding cows four times a day can be logistically complex in a farm setting, and the recommendation is to deliver fresh feed at least two times a day, ideally three, for this group of animals.
Now, none of the practices above will work if cows are not offered a spot at the dining table, which leads to an important factor: proper stocking density. Although this is a broad topic, I will try to summarize it in a few sentences. There are two ways to measure stocking density; one of them is based on the lying surface, or stalls, and the other one is based on the feed bunk space. The safest way to assess this, to guarantee feed availability, is to use the feed bunk space method. By measuring the feed bunk space in inches and dividing that by number of cows in the pen, the space at the feed bunk that each cow has access to can be estimated. Ideally, 30 inches of feed bunk space is required per cow in the pen, which will be equivalent to having a stocking density of 80%-85% based on number of stalls in the pen. Other practices that can increase dry matter intake and modulate stress are keeping the number of pen movements at the minimum possible (to decrease the stress associated with the re-establishment of pen social hierarchy) and avoiding commingling first-lactation cows with older cows.
Many of the practices described above may modulate stress and inflammation to some degree; however, there are specific practices around calving that may have a greater effect. In one of our studies, we found that cows that experienced a difficult calving had an elevated inflammatory response in the days after calving, and subsequently, a higher risk of developing diseases compared to cows that experienced a normal calving. Therefore, timely identification and proper assistance of cows experiencing a difficult calving is critical to decrease inflammation and stress during this time. As I have mentioned in many of my previous articles, personnel training is the very first, and perhaps the most important, step to achieve this. In the same study, we found that cows that experienced dystocia and were treated with a mild anti-inflammatory drug produced almost 10 pounds per day more milk during the first 30 days after calving compared to cows that experienced dystocia but were not treated. Similarly, multiparous cows, regardless of calving difficulty, that were treated with this anti-inflammatory drug had lower systemic inflammation and produced almost 4 pounds per day more milk during the first 30 days in milk compared to cows that were not treated. In a more recent study, we found that cows that received this mild anti-inflammatory treatment approach had reduced incidence of uterine diseases, such as metritis, and also improved fertility. Therefore, there may be an advantage to modulating inflammation after calving. If you noted, I said “modulating” and not “decreasing.” The reason behind this is that cows need the stress and inflammatory responses for natural processes such as parturition initiation and expulsion of the placenta. In a study where cows were treated with a strong anti-inflammatory drug during and after calving, treated cows had a higher rate of stillborn calves, postpartum fever, retained placenta, metritis and decreased milk production.
Management of transition cows is one of the most important aspects of farm management that will set up dairy cows for success during the lactation period. The main goals of these practices must be maximizing dry matter intake and modulating stress and inflammation. Excellent diet formulation and feed bunk management are critical for decreasing the drop in dry matter intake; however, if cows do not have access to the diet, these practices will be meaningless. Calving monitoring and proper assistance, along with mild anti-inflammatory treatment, can be beneficial to modulate stress and inflammation after calving and decrease the losses associated with this period.
Source : psu.edu