Hydrogenated fat-embedded calcium gluconate improves apparent total tract digestibility in lactating dairy cows in a dose-dependent manner.

Supplementation with hydrogenated fat-embedded calcium gluconate (HFCG) is a postruminal prebiotic that has previously been shown to increase yields of milk fat and/or protein, in addition to increased milk urea content. The objectives of this study were to evaluate apparent total-tract digestibility (ATTD) and nitrogen partitioning in response to HFCG supplementation in lactating cattle. Forty-eight lactating Holstein-Friesian cattle (16 primiparous; 31 multiparous) were used in a replicated 4 × 4 Latin square design to evaluate the response to HFCG supplementation at four dietary inclusion rates (0, 0.047, 0.093 and 0.186% DM) over 3-week periods. Apparent total tract digestibility was estimated using TiO2 as an indigestible marker. With increasing doses of HFCG supplementation, ATTD of all evaluated nutrients except ether extract increased linearly, in addition to a linear increase in milk protein yield and quadratic responses in milk urea nitrogen and yields of mixed C:16 and preformed milk fatty acids. No differences were observed in nitrogen partitioning. In conclusion, the improvements in performance observed may be partially explained by an increase in postruminal nutrient digestibility and improvements in gut health in response to HFCG supplementation.