Effects of supplemental calcium gluconate embedded in a hydrogenated fat matrix on lactation, digestive, and metabolic variables in dairy cattle

摘要

There is growing evidence suggesting that by improvinggut integrity and function, less energy is partitionedtoward immune responses related to xenobiotic infiltration,sparing energy for productive purposes. Gluconicacid and its salts have previously shown prebiotic effectsin the lower gut of nonruminant animals, where theyserve as a precursor for butyrate, although evidence inruminants is limited. Butyrate and its fermentative precursorshave demonstrated multiple beneficial effectsto gastrointestinal ecology, morphology, and function,such as the stimulation of epithelial cell proliferationand improvement of gut barrier function and ecology.The objective of this study was to evaluate changes inmilk production, milk fatty acid composition, and fecaland blood parameters in lactating dairy cattle fed ahydrogenated fat-embedded calcium gluconate (HFCG)supplement designed to target the hindgut for calciumgluconate delivery. In addition, the effects of a compoundfeed processing method (i.e., incorporated into amash or an extruded pellet) were tested to evaluate theeffect of extrusion on product efficacy. Forty-five lactatingHolstein cows at approximately 165 d in milk wereused in a 3 × 3 Latin square consisting of three 28-d periods,during which animals were offered a basal rationmixed with 3 different compound feeds: a negative controlin mash form containing no HFCG, or the HFCGsupplement fed at a target rate of 16 g/d, deliveredin either a mash or pelleted form. Supplementation ofHFCG tended to increase yields of milk fat and fat- andenergy-corrected milk. Total yields and concentrationsof milk fatty acids ≥18 carbons in length tended to increasein response to HFCG. Plasma nonesterified fattyacids and milk urea increased in HFCG treatments. Nodifferences were observed in fecal pH or fecal concentrationsof volatile fatty acids, with the exception of isobutyrate,which decreased in HFCG-fed cows. Changesin milk fatty acid profile suggest that increased milkfat yield was driven by increased incorporation of preformedfatty acids, supported by increased circulatingnonesterified fatty acid. Future research investigatingthe mode of action of HFCG at the level of the hindgutepithelium is warranted, as measured fecal parametersshowed no response to treatment.