Dietary potassium diformate improves slaughter performance, systemic metabolic homeostasis, and intestinal health...

A 63-day feeding trial was conducted with 1,800 one-day-old male Qingyuan Partridge chickens, covering three feeding phases: starter (days 1-22), grower (days 23-42) and finisher (days 43-63). Birds were randomly allocated to four dietary treatments with six replicate pens of 75 chickens each: an antibiotic-containing control (ACC), an antibiotic-free control (AFC), and two groups supplemented with 0.45% and 0.60% potassium diformate (KDF), respectively. The evaluated endpoints included phase-specific growth performance, slaughter traits at day 63, routine hematology, serum biochemistry, arterial blood gas profiles, and cecal microbiota characterized via 16S rRNA high-throughput sequencing. Growth and blood indices were analyzed by one-way ANOVA followed by Tukey's post-hoc test, while microbiota data were assessed via PERMANOVA and Kruskal-Wallis rank-sum test. Statistical significance was set at P < 0.05, and 0.05 ≤ P < 0.10 was defined as a statistical trend. Over the entire experimental period, no significant intergroup differences were detected in average daily gain (ADG) or feed conversion ratio (FCR), though 0.60% KDF significantly increased FCR exclusively during the starter phase. The 0.60% KDF group achieved slaughter rate (SR), semi-eviscerated weight ratio (SEWR) and eviscerated weight ratio (EWR) comparable to the antibiotic control, and significantly outperformed the 0.45% KDF group. The AFC group exhibited elevated serum blood urea nitrogen (BUN), uric acid (UA), lactate dehydrogenase (LDH) and creatine kinase (CK), all of which were attenuated by KDF supplementation. The 0.45% KDF group had significantly higher serum carbon dioxide combining power (CO₂CP) and lower chloride (Cl⁻) than both the AFC and ACC groups, while the anion gap (AG) remained unchanged. KDF did not alter cecal microbial alpha diversity but selectively regulated the relative abundance of specific taxa, enriching butyrate-producing genera and suppressing opportunistic pathogens including Gammaproteobacteria. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional prediction revealed that 0.60% KDF downregulated microbiota-mediated infectious disease pathways. Collectively, dietary supplementation with 0.60% KDF was identified as the optimal inclusion level for Qingyuan Partridge Chickens in the present trial. Dietary KDF exerts negligible improvement on overall growth performance but markedly improves core slaughter traits, regulates host metabolism and enriches beneficial cecal microbes. This work provides dosage-specific recommendations and a theoretical basis for KDF application in premium native yellow-feathered broilers in China.