94 Semen Parameters from a Captive Population of the Endangered Chacoan Peccary (Catagonus wagneri) in Paraguay

Abstract

Priority conservation actions for the endangered Chacoan peccary (Catagonus wagneri) include improvement of captive breeding initiatives. Eleven captive male peccaries housed in mixed-sex groups of 17 to 35 animals at the Centro Chaqueño para la Conservación e Investigación in Paraguay were immobilised with intramuscular tiletamine/zolazepam (30 mg; Zoletil® 50, Virbac, Forth Worth, TX, USA), azaperone (10 mg; 50 mg mL⁻¹; ZooPharm, Windsor, CO, USA), and medetomidine (1 mg;10 mg mL⁻¹; ZooPharm). Animals were administered supplemental intranasal oxygen (1-2 L min⁻¹) and reversed with atipamazole (5 mg; 25 mg mL⁻¹; ZooPharm). Testis length, width, and firmness (1-3 scale; 1 = hard, 2 = normal, 3 = flaccid) were recorded. The preputial sheath was clipped, cleaned, and flushed with sterile saline using a Foley catheter. A lubricated 13-mm-diameter electroejaculator probe (Beltron Instruments, Longmont, CO, USA) was inserted into the rectum to a depth of 5 cm. The electroejaculation protocol consisted of 4 cycles of 10 stimuli each (1-4 V/cycle). Collection tubes were changed frequently during electroejaculation to avoid urine or gel fraction contamination of the sperm-rich fraction. Collected semen was evaluated for volume, color/appearance, and pH. Percent motility was determined as the average motility of spermatozoa from 10 fields (40×). Progressive motility of spermatozoa was scored on a scale of 0-5 (0 = dead sperm; 5 = rapid forward progression). Semen samples were assessed for total spermatozoa. Percent of live spermatozoa and spermatozoa morphology were evaluated with Eosin-Negrosin smears. The mean ± standard error of the mean of each parameter is presented. A Pearson correlation coefficient between age and semen parameters was calculated. Males assessed in this study were 10.5 ± 1.2 years old. The mean testis volume was 1005.7 ± 50.9 cm³ and mean testis firmness was 2.1 ± 0.1. The mean ejaculate volume was 2.9 ± 0.7 mL and pH was 7.7 ± 0.3. Few males had motile spermatozoa (n = 5/9), which yielded a mean percent motility of 18.3 ± 8.5 (range: 0-50%) and a mean progressive motility of 0.6 ± 0.3 (range: 0-2). The mean percentage of live spermatozoa was 25.1 ± 5.6 (range: 4-44%). Male Chacoan peccaries in this population had a low percentage of normal spermatozoa (12.4 ± 2.5%; range: 2.8-24.0%). The mean total count of spermatozoa per ejaculate was 1.58 ± 1.01 million (range: 0.09-8.28 million). Spermatozoa defects were predominantly primary (67.1%), with the most common defects being tapered head (15.4 ± 6.2%), diadem/crater (14.8 ± 2.6%), and excess residual cytoplasm (8.5 ± 2.7%). There was no correlation between age and semen parameters (percent live: r = –0.19; motility percentage: r = 0.01; percent normal spermatozoa: r = 0.38; total count: r = 0.29; P > 0.05). This is the first report of semen parameters in the Chacoan peccary. It is unknown whether the poor semen quality is inherent to the species or this population. Reproductive assessment of males from other captive populations and of wild male Chacoan peccaries is warranted.