الفهرس 
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Abstract
The study was conducted at a private commercial rabbit farm in Mansoura City, Dakahlia Governorate, Egypt, from December 2021 to April 2022. The experimental animals included 60 sexually mature APRI line bucks (7-8 months of age and 3.15±0.32 kg live body weight).
The experimental animals (n=60) were randomly divided into six groups (10/group). Bucks in the 1st group (control-NC, G1) were kept under normal indoor conditions (11-22 oC- 40 - 45% RH%) and fed on control diet without supplementation. Bucks in the 2nd group (control-HS, G2) were daily exposed to HS conditions (32±0.50 °C; 60-66% RH) for 6 h (8 a.m. to 2 p.m.) for 3 days/week, returned to the control condition, and fed on control diet without supplementation. Other four treatment groups, including bucks kept under HS conditions as in G2 and fed on control diet supplemented with 1g SP (G3), 25 mg SeNPs (G4), 1 g SP+25 mg SeNPs (G5), and 1 g SP+50 mg SeNPs (G6) per kg diet, respectively. The treatment period was two months, followed by semen collection period of 10 weeks.
Sexual desire (libido) was recorded. During the experimental period, semen was collected for 10 successive weeks (7 wks. for fresh semen and another 3 wks. for semen cryopreservation).
Semen of 70 ejaculates (10 bucks x 7 weeks) were taken. Semen volume (NSV) and pH value was recorded. In each semen sample, the score of mass motility (0-5) as well as the percentage of forward sperm motility, sperm morphological abnormality (head and tail) and, sperm cell concentration, acrosomal status the hypo-osmotic swelling test (HOS-t), membrane integrity was calculated. Total sperm outputs (TSO) per ejaculate was computed.
Cryopreserved semen straws were thawed at 37◦C for 30 s in a water bath. Post-thawed semen was evaluated for sperm forward motility, livability, abnormality, and membrane integrity.
At the end of the experimental period, 5 bucks in each treatment were randomly selected for blood testing. Blood samples were gathered from the marginal ear-vein of the bucks after topical anesthetized by Xylocaine 4% anesthetic into heparinized pipes to assess hematological parameters. Other blood samples were collected into non-heparinized tubes and left to clot, then centrifuged at 700 g for 20 min at 4°C to separate serum collection, which was stored at −20°C until subsequent analyses of blood biochemicals and antioxidant and immunity markers. Hematological parameters included hemoglobin concentration (Hb), packed-cell volume (PVC), and counts of red blood cells (RBCs), white blood cells (WBCs), and platelets. Blood serum biochemical included concentrations of total protein (TP), albumin (AL), triglycerides (TG), total cholesterol (TC), high (HDL) and low-density (LDL) lipoproteins, urea, and creatinine as well as activity of aspartate (AST) and alanine (ALT) amino transferees. Globulin was determined by calculation (the differences between concentration of TP and AL. In blood serum, levels of total antioxidant capacity (TAC), glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA) were assayed. All biochemicals, enzyme activity, and oxidative capacity studied were assayed.
Also, TAC, MDA, and testosterone as well as protein carbonyl levels (POC) in sperm media were determined in the seminal plasma.
Sperm fertility of fresh semen of each group was performed by using 180 sexually mature APRI rabbit females. The pregnancy rate and kindling rate was calculated. Also, the litter size of does and viability rate of kits (total born and alive) were calculated. At weaning (28 days of kit age), litter size and viability rates (live and dead) were recorded.