Optimizing concentrate feeding and calcium-fatty acid supplementation for sustainable milk production in Indonesian smallholder dairy farms.

Calcium-fatty acid (Ca-FA) supplementation has been proposed to improve dietary energy density and milk performance in early-lactation dairy cows. This study aimed to evaluate the effects of dietary treatments varying crude protein (CP) levels, with and without Ca-FA supplementation, on milk production, milk composition, and fat-corrected milk (FCM) in lactating dairy cows across five dairy farmer cooperatives (DFCs) in West Java, Indonesia. The study employed a completely randomized design with a 5 × 4 factorial arrangements. The main factors were DFC location (Bogor, Cianjur, Cisarua, Garut, and Pangalengan) and dietary treatment (CP 16% with Ca-FA, CP 16% without Ca-FA, CP 13% with Ca-FA, and CP 13% without Ca-FA). A total of 154 cows from the five DFCs were included: 42 in Bogor, 33 in Cianjur, 16 in Cisarua, 20 in Garut, and 43 in Pangalengan. Average milk production ranged from 11.22 to 14.86 kg/head/day. Diet significantly affected milk yield (P < 0.05); Ca-FA supplementation at both 13% and 16% CP resulted in similar milk yields, which were higher than those of diets without Ca-FA. Milk fat content was not affected by DFC or diet alone (P > 0.05), but a significant DFC × diet interaction was observed (P = 0.037). Similarly, Ca-FA supplementation at both 13% and 16% CP produced comparable and higher FCM than non-supplemented diets, with no significant DFC × diet interaction. Break-even analysis further confirmed that the additional cost of CP16 could be offset by attainable milk prices and production volumes, demonstrating the economic feasibility of CP16 + Ca-FA adoption for smallholder farmers. In conclusion, Ca-FA supplementation significantly improved milk production and FCM. Supplementation with Ca-FA in early lactation allowed dietary CP to be reduced from 16% to 13% without compromising milk yield or FCM.