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Modern calves need modern milk rations

Dr. Julian “Skip” Olson for Progressive Dairy Published on 11 November 2019
dairy calves

We expect a lot from heifer calves in today’s modern dairy world, which requires more efficiency and consistency for success. Populating the milking herd with any heifer is no longer viable.

Calves have proven they can meet those high standards: doubling their birthweight and growing 4 to 5 inches in stature by 8 weeks is a realistic goal today. Many dairies are freshening healthy, productive, well-grown heifers as young as 21 months. 

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But we’ve also learned we can’t feed a 1970’s diet and expect to turn out a 2020 replacement heifer.

Fortifying: We owe it to the calves 

The old standard of feeding 2 quarts of milk or milk replacer twice a day is outdated. Calves nursing their dams full time would consume much more in 24 hours, and we’ve learned we should do the same.

Modern feeding systems accommodate Mother Nature’s model of providing calves more feed. In some cases, that’s accomplished by using an autofeeder system. Other farms deliver more feedings per day, more milk per feeding or both, through a variety of other management systems. Feeding calves more than twice a day also makes it easier for step-down weaning, shown to make weaning a smooth transition.

It’s also important to recognize that whole milk for calves is not as perfect as we might think. When compared to National Research Council (NRC 2001) guidelines, whole milk is deficient in some vitamins and trace minerals. 

Most milk replacers are fortified to meet NRC guidelines. When feeding whole milk, it’s up to us to supplement their ration with vitamins and trace minerals, just like adding a mineral pack to the lactating herd’s total mixed ration (TMR). Fortifiers can help deliver a nutritionally sound ration to calves. 

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When choosing a fortifier, be sure it is formulated for non-ruminants. Because their rumen is slowly developing, their digestion is more like that of a monogastric animal with a single stomach (the abomasum). Thus, they need B vitamins, along with vitamin C, in their feed supplement.

Balancing for success takes effort

Another key to successfully feed whole milk is balancing fat and protein content. As researchers learn more about lean tissue growth in calves, they have concluded protein should be higher than fat in liquid calf rations when feeding a higher volume of milk. High-protein milk diets promote skeletal frame development and greater deposition of muscle versus fat. Keeping fat levels lower also encourages calves to consume starter grain more readily, which benefits overall nutrient intake and the weaning transition.

A good rule of thumb is a protein-to-fat ratio of about 1.4, such as 28-to-20 or 26-to-18. Whole milk is typically much higher in fat. Calf raisers who feed waste milk, and routinely evaluate the components, find that the dry matter is around 26% protein and 32% fat. If milk this high in fat is fed to preweaned calves, the fat satiety effect leaves them with a lower desire to eat starter grain. The trade-off of lower milkfat feeding results in additional energy consumed in the form of starter grain, which has the added benefit of enhanced rumen development as the calf approaches weaning.

Consistency of whole milk is an additional challenge. Seasonality can alter fat and protein content considerably, even for farms feeding salable milk. If waste milk is fed, day-to-day nutrient levels can fluctuate more depending on which cows contributed to the source and how the milk is handled between the farm and calf. 

Transition milk from fresh cows is higher in solids. Treated cows may have a lower level of solids, and inadvertent incidents of human error – such as adding flush water to the milk or not agitating it properly – can also occur. While standard whole milk contains about 12.5% total solids, farms using hospital milk report ranges of 5% to 14%.

Balancers can help adjust protein and fat levels. These powder supplements are high in protein and, when added with supplemental water to whole milk supplies, can bring every batch of milk to the desired protein-to-fat ratio by diluting fat and extending out the whole milk supply over more calves. Balancer levels also can be adjusted to help calves cope with cold and heat stress.

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It takes management commitment to make balancers work. Total solids in every load of milk need to be evaluated using a tool such as a Brix refractometer. Evaluate solids before pasteurizing, then add the balancer powder and water to meet your feeding goals. 

Always provide fresh, free-choice water to calves and never exceed 16% total milk solids. As total solids levels continue to increase higher than that of whole milk, the resulting higher osmolality levels may put calves at risk of bloat, especially if freshwater access is marginal.

Enhancing the ration further

Fortifiers and balancers can deliver beneficial supplements, including feed-through larvacides, coccidiostats, yeast-based supplements and perhaps direct-fed microbials or essential oils.

How you formulate your liquid calf ration depends on your herd goals. Discussion with your herd nutritionist and veterinarian can help guide these decisions.

While whole milk may be considered an easy nutrition source for calves, feeding it requires attention to detail and careful management. But it’s worth the effort if your goal is to produce productive, modern replacement heifers ready to calve and enter the milking herd in less than two years.  end mark

PHOTO: Photo by Mike Dixon.

Julian “Skip” Olson, DVM

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