Effects of hydrogenated fat-embedded calcium gluconate on lactation performance in multiple commercial dairy herds

Upon fermentation in the hindgut, gluconate acts as a prebiotic having shown benefits in multiple species. In previous studies, hydrogenated fat-embedded calcium gluconate (HFCG), developed to target the hindgut, improved milk and component yields in highly controlled research settings. The objective of the current study was to confirm these results in commercial dairy herds. Six farms, comprising a total of 907 lactating Holstein cows, were enrolled in a randomised cross-over design where the supplementation of HFCG (16 g/cow/d) was compared against a control. Farms were randomly assigned to one of the two possible treatment sequences and treatments were applied for ∼56 d. Milk yield and composition were measured on two milk test-days on approximately d 26 and 56 of each treatment period, and an average per animal per period was calculated. The effect of HFCG supplementation on performance was statistically analysed with two approaches: (1) using individually recorded milk yield and analysed milk composition from each test-day retrieved through the cattle improvement cooperative organization CRV (Arnhem, the Netherlands), and (2) using residual performance obtained by subtracting the observed from the predicted values estimated by the herd test-day model of CRV. Supplementing HFCG increased milk yield (3.6%; P = 0.02), protein content (1%; P = 0.01) and yield (4.6%; P = 0.01), and lactose yield (3.4%; P = 0.04); and tended to increase energy-corrected milk (3.1%; P = 0.10). The analysis of the residual performance retrieved similar trends, although with diminished statistical significancy. During the control period, milk yield, fat and protein yield, and urea content residuals were negative and significantly different from zero (P ≤ 0.05), indicating that farms underperformed relative to predictions. In contrast, during HFCG supplementation, farms performed as predicted. Overall, these results confirm the effectiveness of HFCG supplementation at improving performance at farm level.