Effect of Feed Supplement Containing Dried Kratom Leaves on Apparent Digestibility, Rumen Fermentation, Serum Antioxidants, Hematology, and Nitrogen Balance in Goats

The objectives of the present study were to examine the influence of supplementation with dried kratom leaf (DKTL) on the performance, hematology, and nitrogen balance in goats. Four 12-month-old male crossbred (Thai Native x Anglo Nubian) goats with an initial body weight (BW) of 24.63 ± 0.95 kg were allocated randomly to receive four different levels of DKTL using a 4 × 4 Latin square design. The DKTL was added to a total mixed ration (TMR) diet with doses of 0, 2.22, 4.44, and 6.66 g/day to investigate the treatment’s efficacy. The DKTL was high in secondary metabolites, including mitragynine, total phenolics, total tannins, flavonoids, and saponins. There were quadratic effects on total DMI in terms of kg/day (<i>p</i> = 0.04), %BW (<i>p</i> = 0.05), and g/kg BW.75 (<i>p</i> = 0.02). DKTL increased apparent digestibility with quadratic effects (DM; <i>p</i> = 0.01, OM; <i>p</i> = 0.01, CP; <i>p</i> = 0.04, NDF; <i>p</i> = 0.01, and ADF; <i>p</i> = 0.01). The pH value was within the rumen’s normal pH range, whereas NH₃-N and BUN concentrations were lower with DKTL supplementation, and also reduced cholesterol (CHOL, <i>p</i> = 0.05) and low-density lipoprotein (LDL, <i>p</i> = 0.01). The protozoa population decreased linearly as DKTL levels increased (<i>p</i> < 0.01), whereas <i>Fibrobacter succinogenes</i> increased quadratically at 0 h (<i>p</i> = 0.02), and mean values increased linearly (<i>p</i> < 0.01). The average value of acetic acid (C2) and methane production (CH4) decreased linearly (<i>p</i> < 0.05) when DKLT was added to the diet, whereas the quantity of propionic acid (C3) increased linearly (<i>p</i> = 0.01). Our results indicate that DKTL could be a great alternative supplement for goat feed. We believe that DKTL could provide opportunities to assist the goat meat industry in fulfilling the demands of health-conscious consumers.