Nowadays, it is central to generate innovations that convert agricultural by-products and food waste into valuable animal products while promoting the long-term resilience and sustainability of vulnerable animal production systems. Nutraceuticals (i.e., ‘nutrition + pharmaceutical’) are derived from foods that offer health benefits. In animal production, nutraceutical supplementation with Withania somnifera and Lepidium meyenii has shown positive effects on the endocrine, cardiopulmonary, and central nervous systems. We aimed to evaluate the possible impact of nutraceutical supplementation on rams fed a diet based on surplus feed from a highly industrialized Holstein cow production system, on corporal (live weight [LW], kg; body condition score [BCS], units), metabolic (blood glucose [GLU], mg dL⁻¹; serum protein [PRO], g 100 mL⁻¹), and sexual–testicular variables [sexual odor (ODOR, units); scrotal circumference (SC, cm); testicular volumes (TVOL, cm³); and estimated daily sperm production (EDSP, millions)]. Black Belly rams (n = 12; LW = 70.36 ± 1.2 kg; BCS = 2.96 ± 0.03 units; age = 3.8 ± 0.2 years; 25° N) were divided into 3 experimental groups: (1) WITH, supplemented with Withania somnifera (400 mg kg⁻¹ LW d⁻¹); (2) LEPI, supplemented with Lepidium meyenii (400 mg kg⁻¹ LW d⁻¹); and (3) CONT, not supplemented. The variables LW, BCS, GLU, PRO, and SC, as well as some components of TVOL, did not differ (p > 0.05) among the main effects of treatment or time; only ODOR, right transverse testicular diameter, and total testicular volume differed among treatments, generally favoring the WITH group. Furthermore, the TRT × T interaction demonstrated superior performance (p < 0.05) in the WITH group, with the largest values for LW, GLU, PRO, ODOR, SC, width of the right testicle, volume of the right testicle, total testicular volume, and EDSP. From a productive–reproductive perspective, the Robin Hood Effect—through the use of rejected dairy cattle rations as the base diet for rams—and supplemented with nutraceuticals (WITH and LEPI), emerges as a viable alternative to improve not only the productive–reproductive performance of Black Belly rams, but also other productive and socioeconomic outcomes; the latter contributing to the strengthening of producer and family well-being.

This study capitalizes on computer-assisted semen analysis (CASA) to evaluate a precision nutritional strategy integrating agro-industrial feed upcycling and functional phytogenic supplementation in rams. Black Belly rams (n = 15) sustained on an upcycled basal diet derived from dairy-cow feed rejections were assigned to a non-supplemented control group (CONT) or supplemented with Withania somnifera (WITH) or Lepidium meyenii (LEPI) at 400 mg kg⁻¹ LW d⁻¹. The 64-day trial was conducted from May to July in arid northern Mexico. Sexual drive, seminal quality, and high-resolution sperm kinematics were evaluated using CASA. Body and testicular measurements, ejaculate volume, and most categorical motility traits remained comparable among treatments (p > 0.05). However, phytogenic supplementation enhanced selected seminal and sexual-drive variables (p < 0.05). Crucially, longitudinal treatment × time interactions (p < 0.05) showed that while the CONT group experienced a seasonal decline in local mobility (LOCMOB), it increased from 1.47% to 2.01% in the WITH group, representing a 37% relative increase over time. Moreover, both WITH and LEPI increased LIN and STR by the end of the experimental period (p < 0.05), demonstrating more linear and efficient sperm trajectories. These findings highlight the productive value of upcycled dairy-cow feed rejections and demonstrate that strategic supplementation with W. somnifera or L. meyenii can refine sexual drive, seminal quality, and sperm kinematic efficiency. This integrated bio-circular strategy provides actionable insights for sustainable small-ruminant production under challenging arid summer conditions.