By Lilian Schaer for Livestock Research Innovation Corporation

There is a strong relationship between health and growth in a calf’s early life and that animal’s total lifetime production. This means what happens to a calf in its first few hours and days is extremely critical, particularly what it is fed.

According to Dr. Michael Steele, a professor in the University of Guelph’s Department of Animal Biosciences, what we’ve known to date about what, how much and when to feed calves is changing and opens new opportunities for producers to impact the long-term health, growth and productivity of their animals.

“You can mold the calf when it is born; we call this developmental plasticity, which is strong early in life and goes down as time goes on,” Steele explained during a presentation at the most recent Healthy Calf Conference, where he focused his remarks on evolving perspectives around colostrum and weaning.

Colostrum quality and quantity

Measuring immunoglobulin (IgG) levels is currently the only way to assess colostrum quality. Producers should strive for an IgG level of at least 60 grams per litre, a level that’s been gradually increasing over the last 20 years as the industry develops new recommendations on what those thresholds for calves should be.

Producers with low quality colostrum should consider enrichment with colostrum replacer. The biggest benefit to the calf, research has shown, lies in enriching low quality maternal colostrum with IgG levels of 30 g/l with a dry colostrum source to get the IgG levels to 60 g/l.

“The key takeaway here for producers is that there are ways of dealing with low quality colostrum such as enriching with colostrum replacer to ensure passive transfer,” he said. “We’re also really under-estimating how much colostrum we should be feeding calves.”

Producers should be feeding a calf volume of colostrum greater than 10 per cent of its body weight within the first 12 hours of life. That means a 40-kilogram calf should get four litres of high-quality colostrum, but Steele suggests producers should feed more if the calf will drink it, especially during its first two meals of life.

Quickness also matters; the faster a calf gets its first colostrum feed after birth, the bigger its response will be.

“There is a lot more to colostrum than we give it credit for. Immunoglobulins are the main bioactive, and although our lab is now also starting to look at the carbohydrates and fats in colostrum, there are many other proteins that we don’t talk about,” he says.

Extended colostrum feeding

Producers should also consider feeding colostrum for a longer period of time. Research has shown that calves that received a second feeding of colostrum during their first day also received a big boost in IgGs. Extending colostrum feeding to days two and three after birth, even with a 50-50 mixture of colostrum and milk, improves gastrointestinal development, increases IgG levels and decreases mortality risk. And in days two to 14, feeding a mix of 10 per cent colostrum replacer and 90 per cent milk replacer has been shown to increase body weight and average daily gain, as well as lower the risk of calf death.

Milk feeding levels

Steele cautioned that calves today are heavier and grow faster than they did even just two decades ago. At that time, it was rare to see a 10-week-old calf weighing 100 kg, or recording an average daily gain above one kilogram so older feeding recommendations may no longer apply.

Calves will show more growth in the first month of life the more milk they are able to consume. That’s because they don’t eat as much calf starter as they should during that time, so they lose out on growth opportunities that will never come back.

“Milk consumption changes how the animal grows. Calves fed 1.3 kg of milk replacer per day showed larger mammary glands, liver, pancreas and kidneys than calves only fed 600 g of milk replacer per day,” he explained. “There are a lot of things we need to re-evaluate around milk replacers. We’ve seen in studies, for example, that high fat versus high protein milk replacers can generate the same average daily gain but have completely different metabolic footprints but what the impact of that is, we don’t yet know.”

Delayed weaning with a step-down approach

Weaning is another area where it could be time for some new thinking. Feeding plenty of milk early doesn’t mean producers should wean calves earlier; instead, a farm’s weaning and milk feeding strategies should work in tandem to avoid the growth loss that comes with early weaning.

This doesn’t apply to farms feeding less than five to six litres of milk daily, Steele noted, but for those feeding higher amounts, the highest benefit comes from extending weaning from six to eight weeks of age.

“If you wean too early, it can take six weeks to get them back to the same level of energy intake, so you’ll lose all the growth you gained from feeding higher levels of milk,” he said.

A step-down approach to weaning instead of an abrupt end to milk feeding is important, and although a one-step weaning approach used to be acceptable, Steele now recommends producers strive for at least two steps. That’s easily achievable with automated feeders, but also doable with manual feeding. And when milk is being taken away, calves should be transitioned to high concentrate diets to keep the energy in their ration.

Starch is one of the main calf starter ingredients in Ontario, with levels varying from 10 to 50 per cent. Here too, Steele believes the formula should be tied to a farm’s milk feeding program as research is showing a drop in average daily gain in calves coming from a high milk to a high starch ration, for example.

“Maybe producers feeding lower levels of milk should use a different starter mix than those feeding high milk levels. This is very preliminary yet, but feeding high levels of energy and concentrate is important for this age,” he said.

With the support of Veal Farmers of Ontario and other funders, Steele has just launched a multi-year research project to help address the knowledge gap in the nutrition and performance of dairy beef calves.