Oxidative stress (OS) is brought on by heat stress (HS), which weakens antioxidant defense and initiates OS. Since mitochondria are the primary source of reactive oxygen species (ROS), HS-mediated OS may be lessened by targeting mitochondria with particular antioxidants. The purpose of this study was to investigate the effect of oral coenzyme Q10 (CoQ10) supplementation on the reproductive performance of goat bucks under HS conditions. Ten mature bucks were randomly separated into two groups and housed in an environment with a high-temperature humidity index (THI: 88.3 to 94.8; summer season). The first group (n = 5) got the baseline diet while the second group (n = 5) received supplemental oral CoQ10 (3 mg/kg BW; CoQ10 group) daily for six weeks. Testicular blood flow parameters (TBF), testicular volume (TV) and echogenicity (TE), nitric oxide (NO), seminal alanine aminotransferase (ALT) and catalase (CAT) activities, total antioxidant capacity (TAC), malondialdehyde (MDA) content, and semen quality traits were all measured. The examinations started a week before (W-1), on the first supplementation day (W0), and weekly for eight consecutive weeks (W1-W8). There were marked (P < 0.05) increases in TBF (W3-W6) and TV, and a decrease in TE (W3-W5) in the CoQ10 group compared to the CON group. Similarly, testosterone (T) and NO levels (W3-W5) in the CoQ10 group were higher (P < 0.05) than those of the control group. The CoQ10 group demonstrated significant (P < 0.05) increases in seminal CAT (W4-W8) and TAC (W2-W6) activities and decreases in ALT (W4-W7) activity and MDA (W5-W8) concentration as compared to the control group. The CoQ10 group showed improvements (P < 0.05) at W3-W6 for sperm progressive motility, viability, and normal morphology and at W6-W8 for sperm concentration. In conclusion, oral CoQ10 supplementation improved testicular hemodynamics, testosterone production, semen quality, and antioxidant capacity in goat bucks during summer heat stress conditions.

Fifteen cyclic, multiparous goats were equally stratified and received the common Ovsynch protocol (GPG: intramuscular, IM, injection of 50 mg gonadorelin, followed by an IM injection of 125 µg cloprostenol 7 days later, and a further IM injection of 50 mg gonadorelin 2 days later) or the Ovsynch protocol using nanofabricated hormones with the same dosages (NGPG) or half dosages (HNGPG) of each hormone. The ovarian structures and ovarian and luteal artery hemodynamic indices after each injection of the Ovsynch protocol using B-mode, color, and spectral Doppler scanning were monitored. Levels of blood serum progesterone (P₄), estradiol (E₂), and nitric oxide (NO) were determined. After the first gonadotrophin-releasing hormone (GnRH) injection, the number of large follicles decreased (p = 0.02) in NGPG and HNGPG, compared with GPG. HNGPG resulted in larger corpus luteum (CL) diameters (p = 0.001), and improved ovarian and luteal blood flow, compared with GPG and NGPG. Both NGPG and HNGPG significantly increased E₂ and NO levels compared with GPG. HNGPG increased (p < 0.001) P₄ levels compared with GPG, whereas NGPG resulted in an intermediate value. After prostaglandin F_2α (PGF_2α) injection, HNGPG had the largest diameter of CLs (p = 0.001) and significantly improved ovarian blood flow compared with GPG and NGPG. Both NGPG and HNGPG increased (p = 0.007) NO levels, compared with GPG. E₂ level was increased (p = 0.028) in HNGPG, compared with GPG, whereas NGPG resulted in an intermediate value. During the follicular phase, HNGPG increased (p = 0.043) the number of medium follicles, shortened (p = 0.04) the interval to ovulation, and increased (p < 0.001) ovarian artery blood flow and levels (p < 0.001) of blood serum P₄, E₂, and NO, compared with GPG and NGPG. During the luteal phase, the numbers of CLs were similar among different experimental groups, whereas the diameter of CLs, luteal blood flow, and levels of blood serum P₄ and NO increased (p < 0.001) in HNGPG, compared with GPG and NGPG. Conclusively, the nanodelivery system for the Ovsynch protocol could be recommended as a new strategy for improving estrous synchronization outcomes of goats while enabling lower hormone dose administration.

Drastic climatic changes threaten animal productivity and prolificacy, whose adaptability is governed by its pheno- and genotypic traits. This study was aimed at investigating the effect of coat color on the adaptability of goat bucks under heat stress conditions from the perspectives of testicular blood flow (TBF) and biometry, reproductive hormones, and semen quality. Twenty bucks (Capra hircus) bearing different coat colors were selected from a large flock and divided into four equal groups (n = 5 each) as follows: black coat (BC; 100% black), brown coat (BrC; 100% dark brown), white coat (WC; 100% white), white-black coat (WBC; 50–60% white). Bucks were examined for TBF [Doppler ultrasonography and serum nitric oxide (NO)], testosterone (T) and luteinizing hormone (LH), seminal plasma oxidative biomarkers [catalase (CAT), total antioxidant capacity (TAC), and malondialdehyde (MDA)], and sperm traits percentages [progressive motility (PM), viability (SV), normal morphology (NM), and sperm concentration (SC) once a week for seven consecutive weeks (W1-W7) in the summer season (temperature humidity index = 88.4–92.2). Specifically, at W3-W7, darker bucks (BC and BrC) testicular volume, testicular colored area, T, NO, CAT, TAC, PM, SV, NM, and SC (W7 only) differed significantly (P < 0.05) by decrease than the lighter ones (WC and WBC). Both Doppler indices and serum MDA concentrations were elevated (P < 0.05) at W3-W7 in the BC and BrC bucks compared to WC and WBC groups. In conclusion, bucks with lighter coats were more resistant to the negative effects of HS on TBF, seminal oxidative biomarkers, and semen quality.