P. Lattaioli

Effect of number of motile sperms inseminated on reproductive performance of rabbit does

The relationship between the number of motile sperms inseminated and fertility rate and litter size at birth in rabbits was investigated. A total of 651 artificial inseminations on multiparous rabbit does in different physiological states (lactating or not; sexually receptive or not) were inseminated with a number of motile cells/dose varying from about 1-20 x 10(6). The statistical model computed the following traits: maximum expected value (a), rate of approach to this value (b) and number of motile spermatozoa/dose needed to obtain threshold level (95% of the maximum). The physiological condition of the doe affected the reproductive performance. The sexual receptivity had significant effect during lactation: non-receptive does had the lowest fertility (a: 43.70%; P < 0.05) while no significant differences were found in non-lactating ones (73.80 vs. 89.11%). Also the rate of approach to this maximum was different: non-receptive does showed a higher dependence on spermatozoa number than receptive females (b: 0.69 and 0.58, respectively, in lactating and non-lactating does) and consequently more spermatozoa (13.1 and 11.1 x 10(6) motile/dose) were needed to reach the threshold value. The physiological state of the does did not affect litter size and only 4.1 x 10(6) of motile spermatozoa/dose are needed to reach the threshold value.

Effect of seminal plasma on the characteristics and fertility of rabbit spermatozoa.

The effects of different dilutions of seminal plasma (SP) on the qualitative characteristics of rabbit spermatozoa and on their fertilising ability were analysed. Ejaculated semen was centrifuged twice and the sperm resuspended in media with decreasing ratios of SP/Tris: (1/2; 1/5; 1/10; 1/20; 1/30; 1/100) until the complete substitution was with SP. The control constituted sperm in undiluted SP. Samples were maintained at 37 degrees C and kinetic analysis done at fixed intervals (0-6h). Also the thiobarbituric reactive substances (TBA-RS) values were determined. Rabbit sperm suspended in Tris, or with extremely low content of SP, lost motility and viability within 1-3h, while sperm suspended in SP either undiluted or diluted up to 10-fold, showed similar motility during the 6h period (from 39 to 49%). Further dilutions of SP (1/20-1/30) had no effect during the initial 2h of storage but thereafter the decline of motility was more marked (after 6h: from 0 to 17%). Kinetic parameters followed the same trend and differences were particularly marked after storage: the highest values were in samples diluted up to 1/10; a sharp decline in motility characteristics was observed at higher dilutions. The addition of SP (1/2 v/v) to immotile sperm reactivated 35.5% of cells. However, SP did not significantly affect fertility rate or litter size possible involving an interaction with the female reproductive tract. SP reduced lipid oxidation (TBA-RS) of semen only after storage. A positive correlation between final TBA-RS and cell viability indicated that peroxidation was one of the cause of rabbit sperm deterioration during conservation.

Effect of supranutritional level of dietary α-tocopheryl acetate and selenium on rabbit semen

Abstract This research examined the effects of dietary α-tocopheryl acetate (50 or 200mg/kg diet) and selenium (Se, 0 or 0.5ppm) supplementation on motion characteristics, oxidative stability and fertilizing ability of rabbit spermatozoa, fresh and stored for 24h at 5°C. The higher amount of dietary α-tocopheryl acetate increased the level of Vitamin E in the fresh semen (1.75mmol/l versus 0.95mmol/l) and its oxidative stability (thiobarbituric acid reactive substances—TBARS 12.44nmol malondialdehyde/10 8 sperm versus 21.4nmol malondialdehyde/10 8 sperm). Dietary Se increased gluthatione peroxidase activity (GPx) in erythrocytes (285U/g Hb versus 207U/g Hb), seminal plasma (270U/l versus 190U/l) and spermatozoa (1338mU/10 9 sperm versus 1103mU/10 9 sperm), whereas it did not show any effect on α-tocopherol level and TBARS. No synergy between Vitamin E and Se was shown. Storage for 24h at 5°C increased the TBARS level in all the experimental groups. Neither live and acrosome reacted spermatozoa, nor kinetic parameters, nor fertility rate were modified by dietary supplementation.

Effect of dietary α-tocopheryl acetate and ascorbic acid on rabbit semen stored at 5 °C

Abstract The objective of this research was to verify the effects of dietary α-tocopheryl acetate (50 vs. 200 mg/kg diet) and ascorbic acid (0 vs. 1 g/L water) on the relative amounts on semen and motion characteristics, oxidative stability and fertilizing ability of rabbit spermatozoa stored for 24 h at 5 °C. A high amount of dietary α-tocopheryl acetate significantly increased the level of Vitamin E in the semen (0.90 vs. 0.41 μmol/L) and its oxidative stability after storage (Thiobarbituric Acid Reactive Substances — TBARS 15.88 vs. 20.90 nmol Malondialdehyde — MDA/mL). Ascorbic acid showed a different effect in relation to the Vitamin E status of animals: when associated with the higher level of Vitamin E it increased the α-tocopherol and the oxidative stability of semen (2.67 μmol/L and 12.25 nmol MDA/mL, respectively), whereas both parameters were reduced with lower Vitamin E (0.13 μmol/L and 21.20 nmol MDA/mL). Semen traits were not modified by the separate supplementation of supranutrional levels of vitamins, whereas their combination significantly improved the viability and the kinetics of spermatozoa (e.g. track speed: 95.13 vs. 71.31 μm sec −1 ) with an increase in fertility rate (70.0 vs. 63.3; P=0.06) that could be considered almost significant.