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As a major energy source, fat is an important element to consider in a calf milk replacer. Type of fat and the selection of emulsifiers impact the digestibility of triglycerides (fats), and thus subsequent metabolism and incorporation into body tissues. Fat, however, has other nutritional effects beyond a source of energy. Essential fatty acids, such as omega-3, are critical to support neurological functions and modulation of inflammatory response. Moreover, medium chain fatty acids, such as those found in coconut oil and butterfat, are not only easy to digest by a young calf, but also have positive health benefits due to antimicrobial/antiviral properties. Butterfat offers a unique fatty acid, namely butyric acid. As extensively studied in animal and human research, butyric acid is an interesting short chain fatty acid. The use of butyrate products in humans has shown to be effective in improving intestinal health of individuals compromised with health conditions such as Crohn’s disease.

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Available butyrate products for animal feed are commonly in a salt form, and pose a handling challenge due to smell. A butyrate salt product is sodium or calcium based. Sodium and calcium are loosely bound to a butyric acid molecule, and when dissolved in water, disassociate from each other at varying rates. What this means in the animal is that butyric acid is released in the stomach. For simple monogastric species, such as poultry, beneficial health and efficiency results are presented in research. However, the use of butyric salts in calf milk replacers have shown inconsistent results. This is likely due to the type and dose of butyrate salt, site and extend of release of the butyric acid molecule, with a minimal amount of butyric acid released lower in the gastrointestinal tract (GIT).

Butterfat contains a high amount of butyric acid, on the third chain (or “end” position) of a fat molecule. Lipases are enzymes which breakdown molecules of fat. Enzyme activity is specific to certain molecular structures, and lipase activity is different depending on the type of fatty acid, and its position on the triglyceride. Calf salivary lipases are specific to cleave off the third molecule of butyric acid from a fat, and this happens quickly after consuming milk. In the case of tributyrate (three molecules of butyrate composing the fat), this leaves two molecules of butyrate attached to the glycerol backbone to enter the small intestine where butyrate can impart a biological effect lower in the GIT. The release of one more butyric acid in the small intestine by pancreatic lipases will have a direct effect on the cells in the lower GIT. As this is a new area of calf research, exact changes to the structure of the small intestine, upregulation or downregulation of hormone and metabolic pathways have yet to be specifically determined when using tributyrate in a calf milk replacer. However, anecdotally using evidence from other species, hypothesized changes would be of benefit to gut health and perhaps feed efficiency.

Gro Mega research trials at the Grober Young Animal Development Centre

Innovative technology is required in order to deliver tributyrate in a commercial feed. Grober Nutrition Inc. evaluated the use of a proprietary encapsulated form of tributyrate in a calf milk replacer in three research trials. Overall, there were no differences found for pre-weaning growth or calf health when supplementing the milk replacer with tributyrate. However, interesting results were found regarding starter intake and feed efficiency. Calves fed a milk replacer supplemented with tributyrate tended to have greater starter intakes and improved feed efficiency (results presented in table 1). This is particularly important as jointly improving nutritional intake from milk and solid feed pre-weaning has long lasting benefits into a heifer’s first lactation (Gelsinger, 2016). Not to mention the immediate benefit of improved readiness to wean due to more starter consumed prior to the removal of milk.

Table 1. Summary of data obtained when supplementing milk replacer with tributyrate
Control Tributyrate supplemented
Pre-Wean ADG 950 g/day 975 g/day
Post-Wean ADG 1704 g/day 1830 g/day
Total Pellet Intake Pre-Wean 9.62 Kg per calf 12.04 Kg per calf
Pre-Wean Feed Efficiency 1.71 1.56

Considering the use of supplemental fatty acid products is therefore of relevance to calf nutrition, and can be another tool to improve gut development, integrity, and feed efficiency. Butyric acid can exert positive biological effects such as enhanced gastrointestinal development, more robust epithelial structure in the gut, and promote a shift of the gut microbiome to a more healthy population. Positive effects seen in a calf can therefore be improved feed consumption and efficiency. Timing, dose, and utilization of the correct type of butyrate product, influence the extent of benefits seen.

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