A tool for keeping heifers happy?
With the summer holidays over for many kids, the stress of starting a new school is as good an analogy as any for what heifers have to face joining the milking herd. Most of us are well aware of the turmoil that ensues when groups of cows are mixed and probably know that heifers receive more than their fair share of unwanted attention. Like the newbies off the school bus, heifers are the smallest in the herd and are quick to be pushed to the bottom of the pack as hierarchies are established. As if being the newest in the herd wasn’t enough, our poor heifers are thrown into the deep end as first time fresh cows; exhausted from calving, low on energy and all whilst adjusting to the milking routine. They are in no fit state to defend themselves.
The underlying issue around calving for all cows is a suppression of appetite. Eating is the most important job for any cow and feed intake is a key driver of milk production. She will spend up to five hours per day eating, followed by 10 hours ruminating to digest all that feed, leaving little time for other activities such as milking and resting and even less time if being shoved around. Furthermore a drop in feed intake is a known risk factor for all peri-parturient disease including DAs, ketosis and metritis therefore it’s vital that it’s kept in check. However we tend to make matters worse as we change diet and switch groups, with moving cows alone shown to account for a 2.5-5% reduction in yield lasting between 5-15 days post movement
But what can we do to help?
One way is to create a heifer only group. Research has shown that first lactation heifers kept separate from older cows, spent between 10-15% longer eating, with an increased feed intake of 17-18%. They made more visits to the feed face, spent longer lying and subsequently saw an increase in yield of 4-16%.
Keeping group changes to a minimum can help keep all cows happy. However it’s impractical to eliminate group changes completely as grouping by yield and pregnancy allows us to tailor nutritional requirements to production, minimising waste and maximising efficiency. But we can take steps to reduce the impact of changes.
- House sequential groups adjacent to one another (e.g. dry cows near fresh cows) to allow some contact prior to movement
- Introduce new cattle in small subgroups. Studies show cattle moved in groups of 8 or more experienced fewer negative social interactions than those moved in smaller groups.
- Move cows following afternoon or early evening milking. One study showed moving cows in the night was beneficial (however it only followed a small number of cows).
- Ensure housing has plenty of space especially in cubicle sheds, so that subordinate cows can avoid confrontation.
- Most importantly reduce competition for resources, especially feed, water and lying space. A minimum of 5% extra cubicles should be available and there should be enough feed space for the entire group to feed together, with additional spaces so cows can avoid feeding next to dominant cows.
Finally it’s important to consider when and whether a group change is necessary, especially around calving. A study by Wisconsin University found an increased risk of ketosis and DAs when cows were moved 3-7 days pre-calving. To overcome this the researchers adopted a ‘just in time’ approach to calving with movement to a calving pen at the start of second stage labour (when strong contractions start and the allanto-chorion (water bag) ruptures). If using this approach close observation is essential and it’s important not to move cows too early as this is associated with an increased risk of dystocia.
By ensuring plentiful feed space and comfortable beds, especially around the transition period, and avoiding regrouping in the last 7 days pre-calving you can provide the best start to lactation for your girls.