To investigate the effect of Conocarpus erectus tree leaves and branches as a partial replacement of forage on milk yield and components, blood and rumen parameters of goats, 16 Najdi goats were used in a completely randomized design with 2 treatments (CON, without C. erectus ; CE, contains C. erectus ). The basic ratio consisted of 60% concentrate and 40% forage. In treatment CE, 22.5% of the forage (alfalfa hay and wheat straw) was replaced with C. erectus leaves and branches. The lowest amount of dry matter intake and digestibility were observed in the treatment CE ( P < 0.05). The amount of milk production significantly increased ( P = 0.01) in the treatment CE. The total count did not differ between treatments, but the highest amount of Lactobacillus spp. ( P = 0.01) and the lowest amount of mold ( P = 0.01) were observed in the treatment CE. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity decreased on days 15 ( P = 0.02) and 31 ( P = 0.01) of the experiment in treatment CE. The highest amount of short-, medium-, and long-chain fatty acids and also conjugated fatty acids were observed in the treatment CE ( P < 0.05). Also, the concentration of fatty acids C16:0 and C18:0 was lower in the treatment CE ( P < 0.05). The lowest amount of triglycerides, blood urea nitrogen, cholesterol, low-density lipoprotein, high-density lipoproteins, serum glutamic pyruvic transaminase, and serum glutamic oxaloacetic transaminase were observed in the treatment CE ( P < 0.05). Ruminal pH and ammonia-N concentration were not affected by experimental treatment ( P > 0.05). According to the results, the use of C. erectus leads to improved milk production and fatty acid profile, antioxidant activity, and microbial load.