The transition period, known as the three weeks before and after parturition, is one of the most challenging times for dairy cows, since they face numerous physiological challenges such as increased energy demands, decreased dry matter intake and impaired immune system, among others (Drackley, 1999). These challenges make cows highly susceptible to metabolic (e.g., hypocalcemia and ketosis) and infectious (e.g., metritis) diseases. Ketosis and hypocalcemia are prevalent metabolic diseases affecting dairy cattle that are known as “gateway” diseases, because they increase the risk of other diseases and losses by affecting cow dry matter intake and impairing immune system functions. Therefore, efforts in transition cow management should be primarily aimed at preventing and monitoring these two conditions.
One of the main goals in preventing these metabolic diseases is to minimize the decrease in dry matter intake that cows experience during this period. Practices such as proper stocking density, avoiding commingling first lactation cows with older cows, decreasing pen moves and adequate feed bunk management are crucial to maximize cow intake. For instance, first lactation cows that are housed with older cows in an overstocked pen during the close-up period will produce 1.6 lb/d less milk for each 10% increase in stocking density above the recommended value (i.e., 80%) during the next lactation (Nordlund et al., 2006). In addition, these cows may also suffer a decrease in intake and resting time, subsequently predisposing them to diseases, such as lameness, low milk production and infertility.
When it comes to ensuring proper stocking density, it needs to be considered that this parameter can be measured based on feed bunk space or the number of stalls in the pen. Overstocking at the feed bunk may increase the risk of metabolic diseases, such as ketosis, hypocalcemia and DAs; while overstocking based on stall numbers may increase the risk of lameness (Nordlund et al., 2006). The recommended stocking density based on feed bunk space is 30” per cows; while 80% of stalls filled is the recommended stocking density based on number of stalls (Nordlund, 2011). These recommended stocking densities ensure at least one stall per cow and enough space in the feed bunk to avoid feed bunk displacements of subordinate animals, which compromise feed intake. Also, it is important to keep in mind the barn design when stocking transition cow pens. For instance, in a two-row free stall barn there would be one feeding space for each stall; therefore, stocking density at the feed bunk would equal the stocking density at the stalls. However, most of the modern dairy barns are three-row free stall barns, which means that feeding space at the feed bunk would be reduced by one third if 100% of the stalls are filled. Therefore, stocking pens based on cow feed bunk space requirements is recommended in three-row stall barns.
Another factor to consider when stocking transition cow pens is the feeding barrier in the pen. For instance, in pens with headlocks, cows will only use 80% of the feeding spaces, regardless of the pen stocking density (Nordlund, 2011). Similarly, in pens with post-and-rail feeders, additional space per cow should be provided to prevent dominant cows from displacing subordinate cows from the feed bunk (Nordlund, 2011). Regardless of the well-known negative effects of overstocking in cow health and performance, many producers may overstock transition cow pens thinking that subordinate cows will wait to eat or lay down until dominant cows are done using the feed bunk or the stalls; however, this may not be totally true. Cattle are “allomimetic” animals (herd animals), which means that they like to do activities (e.g., eating, lying down) as a group at the same time (Cook and Nordlund, 2004). Therefore, if subordinate cows do not have a spot in the feed bunk at feeding time, most likely their intake will be affected. A similar scenario would happen if there are not enough stalls for all the cows, which will compromise cow resting time.
Avoiding commingling of heifers/first lactation cows with older cows is often challenging in modern dairy farms due to the additional facilities needed and the high costs involved. The main negative effects of commingling are observed in younger cows that must compete with older and stronger cows for food and lying space. The losses observed are even higher when coupled with high stocking density. Therefore, if heifers/first lactation cows cannot be housed separately from older cows during the transition period, at least the stocking density should be maintained low (80%), specially at the feed bunk (30” per cow).
Another practice that could help improve intake in transition cows is to minimize the number of pen moves. Each time that cows are moved to a different pen, the animal hierarchy has to be established, which takes around 2 days (Cook and Nordlund, 2004). During this time, newly introduced animals in the pen may experience a decrease in resting time and feeding time, which results in a decrease in milk production and an increase in the risk of diseases (Cook and Nordlund, 2004). Therefore, minimizing pen moves of this group of animals may benefit feed intake. Having a combined close-up/maternity pen, where cows are moved 21 days prior to expected calving date and are allowed to comfortably calve in, may help to reduce number of pen moves; however, pen maintenance and monitoring of cows starting labor must be strictly performed.
Perhaps a little easier to manage, feed bunk practices can have an incredible positive effect on cow intake in this group of susceptible animals. In a study, where different feeding barriers and stocking densities were assessed, researchers found that regardless of these factors, the main stimulator for cows to stand up and go to the feed bunk was delivery of fresh feed (Huzzey et al., 2006). Another practice that was found to stimulate cows to go to the feed bunk was pushing-up feed (Huzzey et al., 2006). Therefore, delivering fresh feed ≥2 times a day and performing feed push-ups every 2 h could significantly contribute to optimal cow intake. In addition, other best feed bunk management practices such as providing enough feed, so cows can comfortably grab the feed with their tongue, in the feed bunk for at least 23 hours a day (Caixeta et al., 2018) and feeding for a 5% refusal (Bach et al., 2008) could also aid on maximizing DMI in transition cows.
Even with the best management practices, often, due to unpredictable reasons such as undesirable weather conditions (e.g., heat wave), management can fail to address the transition cow challenges, which could predispose animals to metabolic diseases. Therefore, practices to monitor and treat these “gateway” diseases must be in place in order to identify and address, in a timely manner, transition cow management issues. Routinely monitoring mineral concentrations of dry cow TMRs and urine pH are common practices to ensure that hypocalcemia prevention practices are working properly. Similarly, assessment of transition transition cow body condition scores and ketone body concentrations (in urine, milk or blood) are excellent practices to monitor metabolic status of transition cows and modify management and/or proactively treat subclinical ketotic animals if needed.
Never forget that without a well rationed diet, that provides the right amount of nutrients, minerals and vitamins for the different transition cow groups, none of the above practices will be effective. Therefore, team meetings with farm nutritionists, veterinarians and consultants must be performed on a regular basis to maximize transition cow management, and stay one step ahead of monitoring and preventing future issues.
Source: extension.psu.edu
