Nigerian J. Anim. Sci. 2016 (2):322 - 328 Influence of Human Chorionic Gonadotropin on the Fertility Rate in Artificially Inseminated Rabbit Does
*Ewuola E. O, Amao, T. M, Jones B. O, ++Oni A. A, Adeyemi A. A., and Lawanson, A. A
Animal Physiology and Bioclimatology Unit, Department of Animal Science, University of Ibadan, Ibadan, Nigeria ++Department of Veterinary Surgery and Reproduction, University of Ibadan, Ibadan, Nigeria.
*Corresponding author Email: [email protected]; GSM: +2348060862361
Target audience
Abstract An experiment was carried out on the influence of human chorionic gonadotropin hormone (hCG) on the fertility rate of rabbit does under artificial insemination. The rabbit does (7-8 months old) were used for the trial. The hCG was administered to the rabbit does at varying doses: 0, 50, 100 and 150 I.U representing treatments 1 (control), 2, 3 and 4, respectively. Twenty four does were randomly allotted to the four treatments with six does per treatment in a completely randomised design and the study lasted 5 weeks. The does were inseminated with semen harvested from proven bucks. The results showed that does on 0 and 50 I.U hCG had 0% conception rate, while does on 100 and 150 I.U hCG showed 16.67% conception rate. This implies that hCG at 50 i.u was not enough to initiate ovulation in rabbit does. There were no significant differences (p>0.05) in the weight of doe after parturition, gestation length and litter size among the treatments. Total Litter weight and average litter weight were significant (p<0.05) higher in does administered 150 I.U hCG than those treated with 100 I.U. This study suggested that hCG induced ovulation and influenced the fertility rate of rabbit does when administered with at least 100 I.U to artificially inseminated rabbit does. Keywords: Human chorionic gonadotropin, Conception rate, Rabbit, artificial insemination Description of Problem the underlying causes have not been yet The improvement of reproductive closely examined (1). A number of tools performance on farms is conditioned by and steps are needed to enhance the use of methods enabling the reproductive performance, such as using induction and synchronization of exogenous hormone, nutritional and oestrus. This concerns hormonal mechanical techniques (2). Of the treatments or non-hormonal alternative methods widely used in rabbit methods. Infertility afflicts rabbits, but husbandry practice for increasing
322 Ewuola et al reproductive potential, exogenous induction (4). Alternatively, Luteinizing hormone injection is perhaps the most hormone (LH) or hCG can be used to important technique that has proved to induce ovulation in rabbit breeding be exceedingly effective for breeding programme to enhance fertility (5). In rabbit especially when used with addition, it was found that GnRH and its artificial insemination (AI) (1). The analogues can be used repeatedly knowledge of the hormones that regulate without interfering with the immune the female reproductive activity and its response of hosts (6, 7). The potential of mode of action can help to improve these hormones in both synchronization reproductive management in order to and induction of ovulation in rabbit in increase receptivity and reproductive the tropics has not been adequately efficiency. documented. This prompted the design Artificial insemination which is the of this work to assess the influence of introduction of a male sperm into the human chorionic gonadotropin hormone female genital organs with special on the fertility rate of artificially instruments for its fertilization is carried inseminated rabbit does. out in farm animals for the intensive use of valuable males in order to improve the Materials and Methods breed and productive qualities of Experimental Site animals. For practical application, rabbit This experiment was carried out at the AI is usually carried out with fresh Rabbitry Unit of Teaching and Research diluted semen within 6-12 hours of Farm of the University of Ibadan, Oyo collection resulting in conception rates state, Nigeria. as high as those of natural mating (1). E x p e r i m e n t a l a n i m a l s a n d The success of AI technique in rabbits management depends mainly on the parity number; Thirty female rabbits (does) were used physiological status and sexual for this experiment consisting of twenty receptivity at the moment of four rabbit does and six proven bucks. insemination (2). When using AI, in the The rabbits were purchased from absence of a male, ovulation has to be reputable farms in Ibadan. The animals induced by artificial hormonal were allowed an acclimatization period stimulation. Overtime, the use of of two weeks and were later randomly hormones are employed to synchronise allotted to five treatments with six and induce ovulation in rabbit does and replicates per treatment. The animals the ovulation inducing method most were housed in individual wooden hutch frequently used is an intramuscular (55cm x 40cm x 40cm), managed and application of GnRH (3). fed ad libitum with commercial feed that Gonadoreline, Buserelin, Fertirelin contains 17.78% CP, 7.55% CF and Acetate, and Desloreline hormones are 2525.2kcal/kg metabolizable energy. highly potent, synthetic analogue of Experimental Layout gonadotropin releasing hormone used in The experimental rabbits were rabbit for synchronization and ovulation randomly allotted to four treatments with six replicates per treatment. All
323 Ewuola et al does were inseminated with 0.4ml of number of spermatozoa per mL of pooled fresh semen in the lordosis semen (8). Collective movement of p o s i t i o n . H u m a n C h o r i o n i c spermatozoa of freshly collected semen g o n a d o t r o p i n h o r m o n e w a s was evaluated at room temperature in administered to the rabbits does Just (x400) magnification under the before insemination at varying dosages microscope to determine the mass of 0, 50, 100 I.U and 150 I.U to animals activity of the sperm cells and it is in treatments 1, 2, 3 and 4, respectively. indicated by a +, ++, +++ symbol which Semen collection and Evaluation indicates how active the sperm cells are Semen was collected from the six depending on the activity. The proven bucks A to F using artificial classification of semen was made on the vagina (8). Semen with yellow and basis of waves, eddies and swirls abnormal colour samples was discarded formation. Sperm livability was to avoid deleterious seminal products. determined by putting a drop of semen The ejaculates from the bucks were on glass slide and stained with a drop of evaluated before use. The semen was eosin- negrosin, then it was mixed evaluated in Animal Physiology gently and smeared on a slide, air dried Laboratory of the Department of Animal and viewed under the microscope at Science, University of Ibadan for the magnification of x400. Any sperm cells quality characteristics. The temperature that absorb the stain gave a pink of freshly collected semen from bucks colouration which indicates that those was measured with a digital sperm cells are dead, while the living thermometer and volume of the semen sperm cells will not absorb the stain (8). was measured through the use of Fertility Rate Evaluation tuberculin syringe and graduated test The percentage conception rate was tubes. Sperm motility was done by determined by the numbers of animals adding a drop of semen on the slide and that were pregnant in a treatment divided one drop also of sodium citrate to by the total number of animals in the disperse the sperm cells. This was treatment multiply by100 and recorded covered with a cover slip and place on in percentage. Gestation length was the microscope and observed the sperm measured as the period of conception to cells are motile. Sperm motility was period of parturition in rabbit does. It identified at a magnification of x400. It was recorded in days. Litter size was is expressed as the percentage of sperm also determined by adding the total cells that demonstrated progressive number of kits that was kindled by the motility, from 0 to 100 %. Only samples rabbits does. It was expressed in that showed high motility (>80%) were numbers of kits per doe per treatment. used for on farm insemination The weight of kits was measured by This was done by diluting semen with weighing the kits using a weighing scale formal saline (v/v) for the sperm cells to and the value was recorded in grams. be easy to count under microscope using Weight of the overall kits was divided by haemocytometer and expressed as the number of kits to get average kit
324 Ewuola et al weight in gram. Number of kits that was Results and Discussion alive at the time of kindling was Semen characteristics of bucks used for considered as number of live kit at birth. AI are presented on Tables 1 and 2. The Experimental Design and statistical semen temperature ranges from 34.1- analysis 38.20C. The sperm motility was recorded The experimental design was a complete in percentage and it ranges from 75-85%. randomized design. Data collected were The sperm concentration of buck C analysed using descriptive statistics and recorded the highest value while the Analysis of variance (9) and means were sperm livability of rabbit buck E separated using Duncan Multiple Range recorded the highest value with the Test of the same software. average sperm concentration of 1.85x109 sperm cells/ml. Table 1 : Semen characteristics of rabbit bucks used for artificial insemination Bucks Temperature Volume Mass Sperm Concentration Livabilit O ( C) (mL) activity motil ity (%) (sperm cel ls/mL) y (%) A 37.0 0.81 3 85 1.00 x 109 95.46 B 34.1 0.3 3 80 1.022 x 109 93.46 C 36.1 0.81 2 70 3.54 x108 91.00 D 38.2 1.46 2 70 2.78 x 108 94.88 E 35.7 1.02 3 85 1.69 x 109 97.21 9 F 35.6 0.86 3 80 1.06 x 10 97.92 The influence of human chor ionic range between 32 and 35 days, while the gonadotropin hormone on the fertility litter size was 7 for does on treatments 3 rate of artificially inseminated rabbit and 4. The litter weight was does is presented on Table 3. The significantly (P<0.05) higher in does on gestation length of does in Treatment 3 treatment 4 than treatment 3, while was not significantly different from does weight of doe after birth was in treatment 4. It was observed that none significantly (p<0.05) higher in does in of the does on treatments 1 and 2 treatment 3 than treatment 4. The conceived. The conception rate of the apparently highest gestation length and does in treatments 3 and 4 was 16.67%. average litter weight were obtained in The gestation length of the rabbit does does administered 150 I.U hCG.
Table 2: Mean of semen parameters used for artificial insemination
Parameters Mean ±SD o Semen Temperature ( C) 36.1±1.40 Semen Volume (mL) 0.88±0.37 Mass Activity 2.67±0.52 Sperm Motility ( %) 78.33±6.83 Sperm Concentration (x 10 9sperm cells/mL) 1.85±1.07 Livability (%) 94. 99±2.53
325 Ewuola et al In this study, it was observed that there Garfary et al.(11) which stated that was no conception in does on treatment injecting does with 50 I.U hCG 1 (without hormone) and treatment 2 significantly decreases the number of treated with 50 I.U hCG. This could be services per conception, but increased attributed to the low level of hormone the litter size at birth, litter weight and and absence of the exogenous hormone litter weight gain. The result obtained for administration in treatment 2 and the conception rate of rabbit does administer control, respectively. This implies that 150 I.U of hCG was 16.67%. Also, the artificial insemination in rabbit does values obtained for litter size and require hormonal stimulation to number of live kits at birth corroborates synchronize the oestrus and or induce that of Lavara et al. (12) who reported no ovulation at a level higher than 50i.u for significant differences for litter size at hCG provided semen quality is not birth and live-born kits when synthetic impaired due environmental stressors. It PGF2alpha analogue (cloprostenol) was has been reported that the reproductive used. Pimenta et al. (13) obtained the quality of rabbit buck can be greatly same results after using natural PGF influenced by environmental stress (10). 2alpha and Mollo et al. (14) in Findings from this study are in contrast comparison to does treated with PMSG to those reported by Adams (7) and El- or untreated does. Table 3: Influence of hCG on fertility rate of artifi cially inseminated does with un -extended semen Parameters T1(0 i.u) T2(50 i.u) T3(10 0 i.u) T4(150 i.u) Weight of doe after birth(g) - - 1855.00±7.07 1699.50±6.36 Gestation length (days) - - 32.00±1.41 35.50±0.71 Weight of doe before birth (g) - - 2156.00±7.07 a 1929.00±2.83 b Average Litter size - - 7.00±0.00 7.00±0.00 b a Total Litter weight(g) - - 278.00±4.24 312.00 ±2.83 Average litter weight(g) - - 39.72±0.60 b 44.58±0.40a a,b,c: Means along the same row with different super script are significan tly different
(P<0.05)
The trend of values obtained for litter was within the range reported in weight, weight of doe after birth and the different breeds of rabbits which is average litter weight that were between 28 to 36 days (15). However, significantly different across the rabbit does normally kindle 31-33 days treatments could probably be attributed after mating or artificially inseminated due to influence of the hormone. (16). Gestation length recorded in this study
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Figure 1: Conception rate of artificially inseminated rabbit does administered human chorionic gonadotropin hormone
Conclusion and Application 4. Taponen, J., Hjerppe, P., Kopra, It can be concluded that M.E., Rodriguez, H., Katila, T. 1. Conception in rabbit is impossible and Kindahl, H. (2003).
without exogenous hormonal Premature prostaglandin F2á induction. secretion causes luteal regression 2. However, the use of hCG to induce in GnRH-induced short estrous ovulation will result in conception cycles in cyclic dairy heifers. with optimal dose of 100 I.U. Theriogenology, 60: 379-393. 5. Foote R. H. and Heath A. (1963). References Effect of sperm losses in semen 1. Scinkovicks G., Medgyes., I., and collection equipment on estimated Paljack., J. (1983). Some results of sperm output by bulls. Journal of insemination in rabbit. Journal of Dairy Science, 46: 242-244. Applied Rabbit Research 6: 43-48. 6. Kalaba Z.M. and Abdel-Khalek A.E. 2. Castellini C. (1996). Recent advances (2011). Effect of repeated GnRH in rabbit artificial insemination. injection and intra-vaginal 6th World Rabbit Congress, mechanical stimulation on Toulouse, 2: 13-26. reproductive performance of doe 3. Quintela L.A., Peña, A., Vega, M.D., rabbits. Asian Journal of Animal Gullon, J., Prieto, M.C., Barrio, and Veterinary Advances, 6, 1010- M., Becerra, J., Maseda, F., and 1018. Herradon, P. (2004). Ovulation 7. Adams, C.E. (1981). Artificial induction in rabbit does submitted insemination in the rabbit: The to artificial insemination by technique and application to adding buserelin to the seminal practice. Journal of Applied dose. Reproduction, Nutrition and Rabbit Research. 4, 10-13. Development, 44, 79–88. 8. Ewuola, E.O, Adeyemi, A.A and
327 Ewuola et al Lawanson, A. A (2014). An 13. Pimenta, A. A.; Rebollar, P.G.; improvised artificial vagina for Alvrino, J. M. R. and Alonso, R. rabbit semen collection and the (1996). Induction of rabbit characteristics of the extended parturition by administration of a rabbit semen as panacea for natural prostaglandin F2á. In: artificial insemination. Tropical Proc. 6th World Rabbit Congress, A n i m a l P r o d u c t i o n Toulouse, 107-110. Investigations. 17 (1): 19-24 14. Mollo, A.; Veronesi, MC.; 9. SAS (2003). SAS STAT User's Guide. Battocchio, M.; Cairoli, F.; Version 9.2 for windows. SAS Brecchia, G. and Boiti, C. (2003). Institute Inc., SAS Campus Drive, The effects of alfaprostol (PGF2á Cary, North Caroline, USA. a n a l o g u e ) a n d e C G i n 10. Cherfaoui, D.J., Theau-clement M., reproductive performance of Zerrouki, N. and Berchiche, M. postpartum rabbits. World Rabbit ( 2 0 1 3 ) . R e p r o d u c t i v e Science. 11: 63-74. Performance of male rabbit of 15. Morimoto, M. (2009). General Algerian local population. World Physiology of Rabbits.Rabbit Rabbit Science, 21: 91-99. Biotechnology (Houdebine, L. 11. El-Gaafary, M. N., El-Hamid, M. W. and Fan, J. Editors). Springer and El-Rahim, M. I. (1991). Science + Business Media B.V. Acrosomal damage and enzymic 27-35. Parks J. E., r e l e a s e o f r a b b i t s e m e n 16. Rashwan, A. A., Szendro, Z.S., supplemented with prostaglandin Matics, Z.S., Szalai, A., Biro- F2á. Animal Reproduction Nemeth, E., Szendro, E. and Nagy, Science, 24: 153-157. I. (2003). Effect ofthe time of 12. Lavara, R., Viudes-De-Castro M.P., insemination and the litter size on Vicente J.S., and Mocé E., (2002). the gestation length of rabbits. Effect of Synthetic prostaglandin World Rabbit Science, 11: 75-85 F2á (Cloprostenol) on litter size and weight in rabbit line selected by growth rate. World Rabbit Science, 10: 1-5.
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