Effects of Calcium Propionate Supplementation Levels in Postpartum Dairy Cows on Productive Performance, Milk Mineral Composition, and Fatty Acid Profiles

Calcium propionate serves as an effective feed additive for mitigating hypocalcemia and ketosis in early-lactation dairy cows by providing supplemental calcium and gluconeogenic substrates. This study investigated the effects of varying calcium propionate supplementation levels during the postpartum period on productive performance, milk mineral composition, and fatty acid profiles in dairy cows. Thirty-two multiparous Holstein cows were randomly assigned to four groups (8 cows/group) at calving: a control group (CON) fed a basal diet without supplementation and three treatment groups receiving a basal diet supplemented with 200 (LCaP), 350 (MCaP), or 500 g/d (HCaP) of calcium propionate until 35 days in milk (DIM). All cows were transitioned to the same diet from 36 DIM onward. Productive performance was monitored daily through the peak of lactation (36–125 DIM), with milk samples collected at 7, 21, and 35 DIM for mineral and fatty acid analysis. Calcium propionate supplementation during early lactation tended to increase milk yield during the peak of lactation, with the highest value observed in the MCaP group. The milk K concentration exhibited a quadratic response, with significantly greater values observed in the LCaP and HCaP groups. Conversely, milk Mg and P concentrations decreased linearly with increasing supplementation with calcium propionate. The fatty acid profiles demonstrated a linear decline in the proportions of short-chain fatty acids (C6:0, C8:0, and C12:0) with increasing calcium propionate supplementation. Furthermore, the proportions of C18:2 cis-9,12 and the sum of polyunsaturated fatty acids exhibited a quadratic response, with the lowest values observed in the MCaP group. These findings indicate that calcium propionate supplementation modulates milk mineral homeostasis (K, Mg, P) and alters fatty acid metabolism, concurrently improving lactation performance. The 350 g/d supplementation level achieved the most favorable balance between production enhancement and milk composition, suggesting its potential as an optimal strategy for early-lactation dairy cow management.