Monitoring your calves to stay ahead

In recent years, calf rearing has gained interest among dairy farmers. This is because research consistently shows that calves who grow faster in the first weeks of life will produce significantly more milk in the first lactation. The importance of colostrum and feed intake at weaning is well understood. However, do farmers know their exact performance results?

Since record-keeping is not common on commercial farms, limited figures about calf growth in practice are available. A recent study of 19 farms in Southern England by the Royal Veterinary College in London showed an extreme variation in calf growth in the first six months. The in-between farm variability ranged from 0.23 to 1.25 kg per day with a reasonable average growth rate of 0.77 kg per day. However, variation in daily weight gain within one herd was also large, with ranges of 0.45 to 1.13 kg per day reported on the same farm. Surprisingly, weight gain from 6–15 months was hardly related to weight gain in the first six months.

Overseeing a dairy farm has changed from viewing each dairy cow as an individual to considering the herd as a whole. Consequently, management and nutrition should be adapted to the best-producing members of the herd. Lower producing animals kept in an intensive system will not be profitable. The animals who lag from the start are likely to show both lower milk production in the first lactation and reduced lifetime production (Table 1). Monitoring young calves is essential to preventing a herd of some well-performing animals but instead to have all animals performing well during their first lactation. Herds with little individual variation will produce more and, as a whole, will respond better to changes. Monitoring to reduce internal-herd variability will result in a herd that is both more profitable and easier to manage.

Low mortality rates are the first indicator of excellent calf rearing, as it reflects if basic nutritional and housing needs are achieved. Mortality rates tend to rise when herd size increases, this is often because less attention can be given to individual calves. International studies mention stillbirth rates of 6–12% (including the death of calves < 24 hours) and further mortality in the first year at 6–8%. Ideally, the stillbirth rate and mortality rate in the first six months should be below 5%. The best farms obtain mortality rates below 1.6%.

The ultimate goal for a uniform and well-developed herd at calving requires precise evaluation of heifer performance. Bodyweight is preferably measured three times: at birth, at six months, and around the moment of insemination; the latter can be checked by the withers height as well. Body condition should increase gradually during rearing to end at 3.0–3.5 points at calving (Table 2). Bodyweight at six months is critical because higher growth rates before six months of age are positively correlated to higher milk yield in the first lactation. However, higher growth rates after six months of age do not correlate to higher milk yield. Ideal body weight at six months can only be achieved if growth rates are consistently at a high level from the beginning.

Weighing is preferably done at the same moment as another management practice, like vaccination or moving. Plotting the obtained body weights directly in a graph (Figure 1) makes it easy to determine if the target weights (or heights) are being met and whether underperforming animals should be referred to as a specific group of animals or season. The trends of this data can provide insight on management or nutritional needs:

Realistically, no farm can always have perfect housing conditions and feed supply for all calves. A certain level of infection pressure or unprecise feed supply is always present; with some underperforming animals as a result. In this case, opting for more safety in the feed can be a valuable option. In a 10 week trial with 52 male Holstein Friesian calves, starting at 14 days of age, Aromabiotic® Cattle—a specific blend of medium-chain fatty acids (MCFAs)—reduced the number of underperforming animals. All calves in the trial were kept in the same group—thus infection pressure was the same—and the prestarter was supplied by automatic individual feeding. The half of animals that received an MCFAs containing prestarter needed fewer treatments. Treated calves in the control group showed impaired growth (-6%), while the calves receiving MCFAs did not (Figure 2).

Gathering data is valuable for management decisions. First, by identifying and improving calf rearing management. Second, providing insight for better selection of animals before calving, or even before inseminating. Tracking weight and providing nutritional support against the innate challenges calves face, like medium-chain fatty acids, are valuable tools to encourage uniformity in the herd. In conclusion, monitoring on commercial dairies is needed to improve management. This will give technical insights for positive economic results and facilitate more advanced management decisions.