On a dairy farm, there is certainly no shortage of data. Key performance indicators for milk production and livestock health have come to form an indispensable part of modern-day livestock farming and with the advent of sensors, the flow of data has expanded still further. In a large-scale practical study, Utrecht University, Wageningen University & Research, Vetvice and Nedap are seeking to identify a method that will make it possible to derive practical value from the information provided by sensors. In a series of articles, we will look over their shoulders as they carry out their research. In this edition: A separated group of heifers produces more milk.
Produce more milk with a separate group of heifers
It takes at least one month before the behavior of dairy heifers normalizes in a herd with mature cows, the practical study Sense of Sensors shows. Heifers demonstrate specific behavior, have different needs and thus merit special care.
They require more lying time, have a higher feed intake and produce almost 10% more milk. The advantages of housing dairy heifers separately are well-known. American dairy scientist Rick Grant already published impressive data in this field in 2012. Despite that, it is still rather unusual for dairy farmers to keep their heifers apart from older cows. “What many farmers don’t realize is that heifers represent a separate group of animals. They exhibit specific behavior and have different needs”, says Assistant Professor Frank van Eerdenburg of the Faculty of Veterinary Medicine in Utrecht. Van Eerdenburg is involved in the practical study Sense of Sensors. In part 3 of the series on this study, he explains the reasons why every farmer should consider arranging a separate group for dairy heifers in the stable.
When everything is new
On introduction to the livestock, heifers are at the bottom of the pecking order. They are smaller than adult cattle and experience greater stress. “For heifers, everything is new. They undergo a metabolic change for the production of milk and need to learn to walk to the milking parlor and the feeder,” says Van Eerdenburg. “In a separate group, heifers face less stress because they do not get into conflict situations with older animals. This not only contributes to increased milk production, but also improves the wellbeing of the animals.” For small businesses, separate housing of heifers is more difficult to achieve, but, in Van Eerdenburg’s opinion, it is feasible to look after them as a separate group from as few as a dozen heifers.
More steps, more stress
The practical study Sense of Sensors shows, among other things, how it takes at least one month before heifers get used to their new herd and surroundings. This graph demonstrates for three regimes how many extra steps heifers take in comparison to the herd. The closer the lines get to zero percent, the more similar their behavior is to that of the mature cattle.
It is even clearer that introduction after three days leads to greater stress (more steps) than doing so right after calving. Certain farmers wait a few days with the introduction of heifers into the herd, but this effort is in fact in vain. Van Eerdenburg: “On the day of calving, heifers are geared up to defending their calf, and are thus more assertive. This is hormonally driven.”
The advantages of a separate group of heifers are all well and good, but what happens if the heifer still ends up in the group of mature cows after her second calving? “This question is justified, but the problems at introduction are not extended. The advantage of keeping a separate group of heifers lies in particular in being able to better respond to heifers’ typical eating behavior,” says project coordinator Jan Hulsen. Heifers eat more slowly than mature cows; they will more easily get the extra time needed in a group of peers than in a group with dominant older cows. The routine of milking and feeding is no different during the second lactation, as is well-known.
However, the new second cow calf will still have to determine her ranking. Hulsen: “However, this already happens after two or three days, that is not the problem in regards to introduction.” The occupancy of the barn is especially important, argue Hulsen and Van Eerdenburg. “Occupancy of more than 80% already impacts on milk production,” claims Van Eerdenburg. “Heifers need to lie down for twelve to fourteen hours a day. At ten hours, you already lose money. Each extra hour of lying down yields one and a half kilos of milk. This also explains the additional milk in a separate group of heifers. Sensors can precisely demonstrate this.”
Paul van Asseldonk:
“The BSK* of dairy heifers is higher now than that of more mature cows”
*BSK: Standardized milk production value for each cow to the 50th day of the third lactation period
For Paul van Asseldonk, milk heifers no longer have to compete with their mature barn companions. Since September of last year, the dairy farmer from Rosmalen has been tending to his first calf animals in a separate group. “The genetics of the youngest cattle are of the highest level, but this was never evident to us in the BSK and lactation value,” Van Asseldonk. The farmer milks using three robots, one of which is specifically reserved for the heifers. His dairy farm is part of the Sense of Sensors study. From when the heifers were kept in their own section onwards, the BSK value increased significantly by 2.5 kilos of milk per animal (table 1). The number of steps dropped by 400 and the lying time increased by 37 minutes per day. This all points to a lowering of stress. “The BSK is now higher for the heifers than for the adult cows. At the most recent milk recording, the heifers showed a BSK of 54.7 and the cows 51.7,” states Van Asseldonk satisfactedly. “However, I had expected the heifers to also be eating for a longer period, but actually the reverse happens. It seems that they can eat to capacity more quickly and then find a quiet spot to lie down and ruminate.”
