Day in day out I put together ration after ration designed to try and maximise milk production, health and fertility. In reality there is very little variation in the nutrient profile of these diets. Although the forage quality between farms vary, the biggest likely cause of variation will be the environment, management or the non-nutritional factors associated with the cows environment.
It is now a 7 years since Alex Bach (2008) characterised the most influential non-nutritional factors that accounted for over half the variation in milk production level between herds fed the same diet and of similar genetic merit. Most dairies however are still not recognising all these factors as being significant and applying management changes to address them.
According to Bach the following factors had the biggest effect on milk yield variation
- Age at first calving
- Presence or absence of feed refusals
- Number of push-ups per day
- Stalls per cow
These factors explained 56% of the variation in milk yield between herds; a staggering 32% was attributed to stocking density of the herds.
The majority of these non-nutritional factors have one thing in common and that is that they are directly or indirectly affecting the time budget of the cow and influencing the time spent lying down producing milk. Below is the target time budget of a dairy cow.
A cow’s time budget will come under pressure if she spends more than 2.5-3 hours away from the pen and feed. In a research study cows were kept away from the pen and fed for 3 hours instead of 6 hours per day. When the time away from the pen and feed was halved the cows gained 2 hours of resting time and 2 litres of milk, heifers gained a staggering 5 hours of resting time and nearly 4 litres of milk. Lame cows identified as having a locomotion score of 3 and above are even less tolerant of time away from the pen and feed. For these cows milk yield will begin to decline after just half an hour away from the pen and feed.
The time spent away from the stall and feed can be greatly reduced by matching group size to parlour capacity. On twice a day milking group size should be no more than twice the hourly capacity of the parlour and on thrice a day milking no more than 1 times. Segregating cows for routine vet checks or treatments can have a big effect on time budgets. Although headlocks are a great management tool and can help reduce the need to segregate cows, time spent in a lockup should be limited to 1 hour per day
Ideally heifers should be grouped separately to cows. In mixed groups the performance of heifers is compromised more than mature cows at higher stocking rates. As stocking rate increases the difference between the performance of heifers and cows also increases. When heifers are grouped separately feeding times, meals per day, lying times, lying periods, DMI and milk yield will all increase.
Trough design, feed availability, feeding times, feed space and diet composition will all effect milk yield however, there is an interesting dynamic between lying times, eating times and DMI which is often not taken into account. A cow will sacrifice 1 minute of eating time for every 3.5 minutes of resting time lost. They will stand waiting for a stall rather than go and eat. Based on this principle we can calculate the effect this has on DMI. In a 24 hour period we would like our cows to eat say an average of 24kg of DM. That equates to an eating rate of 80g/minute of DMI in the 5 hour time budget available. A loss of an hour lying time would equate to a loss of 1.4kg DMI worth quite easily 2+ litres of milk per cow per day.
Getting lying times and eating times working in harmony can only be achieved if the cows have adequate space to lie down, on comfortable beds and have adequate time to do so. Optimal DMI can only be achieved if again the cow has ample space, in a well-designed feeding area, serviced with regular and adequate feed deliveries and push-ups.
A stocking rate of greater than 120% has been shown to limit the performance of the dairy cow, and have a greater detrimental effect on the performance of heifers. Higher stocking rates can be tolerated if cows and heifers are in separate groups or if fresh cows are kept in a separate group. Stocking rates greater than 120%, especially for freshly calved cows will result in increased rates of displacements, reduced lying times, faster eating rate, reduced rumination and increased idle time spent standing in alleys.
The stocking rate of the stalls should not be considered independently of the feed space availability. For example 100% stocking in a three row barn is already overstocking the feed bunk or barrier by 33% based on a feed space requirement of 2ft per cow. In situations where the feed fence is overstocked a number of measures can be taken to limit the negative effect.
Allowing cows to move directly back from the parlour post milking to a feed fence that has been fed up during milking will significantly improve the situation. Quite simply this results in stocking rate pressure at the feed fence being more staggered. As the last of the cows to be milked are coming out of the parlour the first cows out will be close to finishing eating and will have gone to lie down.
Increasing the frequency of push-ups during day light hours will stimulate the cow to eat and increase DMI. The biggest motivators of DMI are time of day and milking. For this reason it is essential that feed is available to the cows as they return from milking. More importantly ensuring that there is sufficient fresh feed at the feed bunk at dawn and just before dusk. During the morning feed cows can eat anywhere between 35-60% of daily feed requirement. There is no benefit from feeding cows more than twice per day. It is also important to remember that cows are herd animals and therefore like to eat as a herd. Other design features which will promote DMI include a smooth surface to the feed bunk, a feeding level of 4 to 6” above ground level, a feed rail 1.5m high set 30 degrees forward over a dwarf wall 0.5m high.
Stall design and stall surface will have a bearing on lying times. Lying times can be increased by selecting the right kind of stall base as outlined in table 2.
Depth of bedding has a profound effect on lying times; basically the more you put on the longer the cows will lie down and the more time they will have for eating. Feeding frequencies greater than twice daily reduce lying times. Stall dimensions and design are also important, most common mistakes are length of bed, especially where the stalls are placed against a wall, neck rail height and brisket board height. From a management point of view maintaining stall fill especially in deep bedded systems is a common fault.
Finally, Empathy and gentle handling of the cows is essential. Aggressive handling and vocalisation has a negative effect on milk yield and residual milk at milking time.
Interestingly most of the points and recommendations covered in this article do not involve a large amount of capital expenditure to implement but will result in healthier more productive cows.