Inclusion of calcium propionate in a protein supplement for replacement beef heifers fed low-quality forage: Growth performance, body fat reserves, and economic return

Objective Our objective was to evaluate the effects of different inclusion levels of calcium propionate (CaPr) in a protein supplement on growth performance, feed efficien-cy, body fat reserves, and economic return of replacement beef heifers managed under dry-season conditions and fed low-quality forage. Materials and Methods Forty full-blood Beefmas-ter heifers (~334 kg of BW) were randomly assigned to receive 0, 20, 40, or 60 g of CaPr/heifer daily for 42 d in a completely randomized design. Heifers were individually housed and fed a protein supplement (0.84 kg/d; 48.5% CP) plus ground corn stover offered ad libitum. Body weight and feed intake were recorded every 14 d, body fat reserves were assessed by ultrasound, and an economic evaluation based on feed costs was conducted. Results and Discussion Low-to-moderate CaPr in-clusion (20 to 40 g/d) improved BW gain and feed efficien-cy, reduced residual feed intake, and increased rump-fat thickness without affecting rib-fat thickness or longissimus lumborum area. In contrast, the highest dose (60 g/d) at-tenuated productive responses. Inclusion of 20 to 40 g/d increased income over feed costs and reduced cost of gain, whereas 60 g/d increased feed costs without productive benefit. Implications and Applications Supplementation with CaPr at 20 g/heifer per day (effective range 20 to 40 g/d) represents a practical strategy to support positive energy balance and body fat reserve accretion in dry-season beef systems relying on low-quality forage. Under these conditions, CaPr supplementation can improve growth performance, feed efficiency, and economic return without the negative associative effects commonly observed with cereal grain supplementation.