In most calf milk replacer formulations today, the fat content is equal to or lower than the protein level, and the fat typically falls in the range of 18-20%.
But is that tried-and-true standard worth challenging? Dairy researcher Dr. Marcos Marcondes with the W. H. Miner Institute, Chazy, NY, believes it is. Marcondes and his colleagues have been recently studying the effects of raising fat levels in milk replacer.
Marcondes shared on a recent episode of the Dairy Nutrition Blackbelt podcast that fat in milk replacer has always been a challenge. While all-dairy milk replacer ingredients are highly desirable, butterfat has high market value, so the industry has sought less-expensive fat sources for calf milk replacers.
“In the 50’s and 60’s, there were a lot of links between high-fat milk replacers – especially those with vegetable fats – and a high incidence of scours,” he explained. “So, for many, many years, the great majority of milk replacers were formulated using a low-fat and high-lactose content.”
While lactose can be an effective swap in terms of energy content that may equal that of fat, Marcondes said it does bring its own set of issues. High lactose will increase the osmolarity of the gastrointestinal tract, meaning that it draws in more water to the digestive system. “This can result in more watery feces, and some view it as problematic because it speeds up the passage rate of nutrients through the digestive tract,” said Marcondes.
Marcondes’ work with higher-fat milk replacers has shown improvements in health, and sometimes growth performance compared to high-lactose formulations. “Usually when we replace a high-lactose calf milk replacer with a high-fat formulation, we’re not expecting huge changes in performance in terms of average daily gain or body weight at weaning,” he noted. “However, we are starting to see very consistent results in terms of calf health, especially in terms of fecal consistency, scours, and some other health status.”
Just what level of fat are they studying? A least 28% said Marcondes. While that may sound high, he said it actually gets calf milk replacer much closer to the fat content of whole milk, noting that a 4.2% butterfat test would be equivalent to 32-33% fat on a dry-matter basis.
And it can’t just be any fat source. “We’re not using a lot of corn or soybean oil, because they are linked to those bad results of the past,” he noted. “They are high in polyunsaturated fatty acids, and we need to use saturated fatty acids.” Animal fat sources like lard, tallow, and choice white grease; or vegetable sources like palm, rapeseed, and coconut fat can provide much more desirable fatty acid profiles.
Marcondes said additional benefits to feeding higher-fat milk replacer include:
- Antioxidant properties of fat.
- Linkages between fat and better absorption of vitamins A, D, and K.
- Improved immunity due to more effective lipid storage and energy utilization efficiency.
- Better liver metabolism, thanks to improved oxidization of fat in the liver and improved distribution of fatty acids from the liver to the rest of the body via very low-density lipid protein (VLDL).
Finally, Marcondes said his research has shown that high-fat milk replacer formulations typically contain 5-10% more energy than high-lactose formulations, which can be helpful in addressing higher seasonal energy requirements. “Farmers tend not to adjust to cold-weather feeding, so that extra energy intake could be a good bump in the wintertime, especially if the calves are housed outside,” he shared.
