Due to competition for resources, overcrowded cows spend less time lying, show increased aggression and feeding rates at the feedbunk, display greater risk of subacute ruminal acidosis and are at increased risk of lameness. Despite more limited research into the impacts of overcrowding on transition cows and heifers, we can apply the typical behavioral changes in lactating cows to make nutritional and management recommendations for these two production stages.
Overcrowding during the transition period is often not advised, with typical industry recommendations 80 to 100 percent of resources from the close-up period through two to three weeks of lactation. Due to the increased stress on the cow during calving, overcrowding can exacerbate this stress, resulting in lower peak milk, increased metabolic issues and greater 60-day cull rates. However, seasonal breeding or heavy calving months can overwhelm limited transition facilities. During these intermittent periods of overcrowding:
1. Formulate mixed parity pens with first-lactation cows in mind – In mixed parity dry cow pens, first-lactation cows are often subdominant to more mature animals, resulting in less access to fresh feed. Making rations denser can allow subdominant first-lactation animals to maintain proper nutrient intake, particularly anionic salts if the herd is on a negative-DCAD program. If possible, separating parities during the close-up period can further reduce stress and set first-lactation cows up for success through transition.
2. Provide a well-mixed TMR with ample access – Due to drier feed ingredients such as hay or straw, dry cow diets can be challenging to prevent sorting. Often, cows will sort for the smaller concentrate package immediately following fresh feed delivery, leaving subdominant or first-lactation heifers without proper concentrate intake. Carrying vital vitamins, minerals, transition additives and metabolizable protein, concentrate intake is important for colostrum production and immune support, as well as proper peaks. Ensure diets are properly mixed, add water or molasses to keep concentrate in mixture and make sure forage is proper length (less than 4 inches) to reduce sorting drier forages. Further, keep feed pushed up following feed delivery to allow subdominant animals access to the full TMR rather than picked-through feed.
3. Identify movable fresh cows to minimize overcrowding – Challenge your fresh cow moving programs away from set days in milk (DIM); rather, identify healthy cows ready to move to high pens. Keeping healthy cows on fresh cow diets too long can not only limit dry matter intake (DMI) and energy balance, impacting peak yield, but it can keep higher numbers of cows in transition pens unnecessarily. During times of heavy calving and higher stocking density in fresh pens, work to identify cows with issues that need closer attention and treatment versus those ready to move and lessen the crowding.
In the last year, we have seen the industry make great progress to limit heifer populations to true farm replacement needs. Whether breeding lower-potential cows to beef semen, culling calves with health issues or culling problem breeders, overcrowding has lessened on many farms. However, some farms are still going through this transitionary phase, with previous heifer inventories creating significant overstocking in older heifer facilities.
Two main points of a heifer program are to achieve adequate growth (95 percent mature weight pre-calving) and maintain appropriate body condition. Overstocking can create significant variation within heifer pens, limiting their ability to achieve maximum potential following calving. During this period, while reducing excess heifer inventories:
1. Feed extra fiber – Due to competition at the feedbunk, overcrowding can lead some heifers to overeat higher-nutritive feed and gain excessive bodyweight while others struggle to maintain intake. Feeding higher physically effective diets (well processed) can minimize condition variation in the pen, leading to more uniform diet intake.
2. Avoid limit feeding simultaneously – Overcrowding heifers creates significant competition at the feedbunk and increases physical altercations or displacements. Limit feeding, and creating stretched periods without feed, can exacerbate this aggressive behavior once feed is finally delivered. This can result in slips and falls at the feedbunk, increased slug feeding behavior that predisposes rumens to increased risk of SARA and increased risk of heifers falling behind growth curves.
3. Analyze heifers on an individual basis – Subdominant animals may not grow fast enough for on-farm goals and will enter the milking herd at a lower bodyweight and height if moved/bred with the rest of their pen. Consequently, these small heifers need to spend some of their first-lactation milk potential to finish growing. Look at heifers on an individual basis and ask yourself these questions: Are they ready to move onto the next pen or should they be held back? Are they ready to be bred or do I need to delay a reproductive cycle or two? Measure and monitor individual heifer growth where possible to determine if they are ready for the next stage.
4. Prioritize cleanliness and safe flooring – Overcrowded pens tend to get dirtier much faster due to the high foot traffic in the pen. This excess manure can lead to more slick surfaces, which can lead to involuntary culls from splitting heifers and foster an environment with greater spread of disease such as hairy heel wart. Increase bedding amount and frequency in heifer pens to promote cleaner and safer pens.
While overcrowding heifers, and particularly transition animals, may not be the most ideal for setting animals up for a successful lactation, limited facilities and unequal calving months make this practice inevitable on most farms. However, limiting additional stressors with detailed nutrition and management practices can set cows and heifers up for better health, production and overall success in the herd. 
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Mac Campbell
- Cargill Dairy Specialist
- Cargill Animal Nutrition
- Email Mac Campbell
