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Scrotal Circumference, Daily Sperm Production and Epididymal Spermatozoa of the Indigenous Bunaji and Sokoto Gudali Bulls in Nigeria
Br. vet.). (1983). 139,487
SCROTAL CIRCUMFERENCE, DAILY SPERM PRODUCTION AND EPIDIDYMAL SPERMATOZOA OF THE INDIGENOUS BUNAJI AND SOKOTO GUDALI BULLS IN NIGERIA
Bv C.
SALAU DAuou AND
V.
SHOYINKA
Department of Veterinary Surgery and Obstetrics and Department of Veterinary Microbiology and Pathology, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria.
SUMMARY
Testicular and epididymal tissues were obtained from 10 Bunaji and 10 Sokoto Gudali bulls aged four to five years. Testicular weights (paired sides) were 298·71 ± 12·55 and 412·24 ± 14·94 g for the Bunaji and the Sokoto Gudali bulls respectively. Scrotal circumferences, as determined on live animals, were 34·12 ± 0·42 and 34·54 ± 0·65 em for Bunaji and Sokoto Gudali bulls respectively. Scrotal circumference was positively correlated to the testicular and caudal epididymal spermatozoa in both breeds. Daily sperm production was estimated to be 4·15 X 10 9 and 3·57 X 109, while epididymal transition times were 4·18 and 5·71 days for Bunaji and Sokoto Gudali respectively. INTRODUCTION
The reproductive potentials of various breeds of bulls have been well documented (Almquist & Amann, 1961; Igboeli & Rakha, 1971; Amann et al., 1974). In artificial insemination programmes information on the reproductive capacity of the bulls is essential to facilitate the detection and exploitation ofbulls ofhigh genetic potential. In Nigeria at present, Bunaji, Sokoto Gudali and Friesian bulls are used in artificial insemination programmes. However, adequate information on the sperm production rate of the indigenous bulls is not available. The present study was designed to provide information on the daily sperm production and the epididymal sperm reserves of indigenous bulls. MATERIALS AND METHODS
Ten Bunaji and 10 Sokoto Gudali bulls, aged four to five years, were used. Scrotal circumference was determined at the point of the greatest scrotal-testes complex in the live animal. Following slaughter, the genital tract was removed; the testes and
BRITISH VETERINARY JOURNAL, 139,6
488
epididymides were removed from the tunics and unwanted connective tissues. The tract was then separated into testes and caput, corpus and cauda epididymides, and weighed. The right and left sides of these portions were treated separately. Each testis was homogenized for I min in a normal saline solution containing 0·05% Triton X-1 00 (v/v). The caudae epididymides were each similarly homogenized for 2 min. The volume of the homogenate was determined and emptied into a conical f1ask containing known quantity of 0·17% saponin in 0·5% formalin solution as a preservative. The final volume of the homogenate used for counting was determined and recorded. Counting was done haemocytometrically on the day of homogenate preparation and 24 h later. Each homogenate sample was counted four times and the mean recorded . The results were analysed statistically. RESULTS
The results arc presented in Table I. Scrotal circumference was positively correlated to the paired testicular weight (r = 0·96), testicular spermatids/spermatozoa (r = 0·84) and the caudal epididymal spermatozoa (paired sides) (r = 0·88) for the Sokoto Gudali bulls and for the Bunjai bulls (r = 0·91, r = 0·87 and r = 0·89 respectively). Testicular weight (paired sides) was significantly (P<0·05) greater in the Sokoto Gudali compared to the Bunaji bulls . In both groups of bulls the right testes were significantly heavier than the corresponding left testes. This asymmetry was not observed in the other paired reproductive structures. However, the caudae epididymides (paired sides) of the Sokoto Gudali were significantly (P<0·05) heavier than those of the Bunaji, and the caudal epididymal sperm reserves (paired sides) were significantly (P0·05). TABLE!
REPRODUCTIVE PARAMETERS OF 10 BUNAJI AND 10 SOKOTO GUDALI BULLS IN NIGERIA
Parameters
Scrotal circumference em Testicular weight (paired sides) g Epididymides (paired sides) Caputg Corpus g Caudag Sperm reserves X I 09 Testes (paired sides) Epididymal sperm reserves X 109 Caput Corpus Cauda Daily sperm production X I 0 9 (time divisor 5·32) Epididymal transit time days
Bunaji bulls
Sokolo Gudali bulls
34·12:!: 0·42 398· 71 :!: 12·55
34·54:!: 0·65 412·24 ± 14·94
24-85 :!: 2·42 8·57 ± 1·06 18·76:!: 2·97
23·81 :!: 2·04 4·61 :!: 0·47 25·7 ± 2·60
22·06:!: 2·78
19·02:!: 2-47
5·05:!: 0·83 2·48:!: 0·14 9·91 :!: 0·77 4·15
5·50:!: 1·09 I ·25 :t 0· 1 I 14·60 ± 1·69 3·57
4·18
5·71
REPRODUCTION PARAMETERS IN NIGERIAN BULLS
489
DISCUSSION
The scrotal circumference observed in the present study for the Bunaji and the Sokoto Gudali falls within the range earlier reported for these bulls (Osinowo et al., 1977). The testicular asymmetry observed was also recorded by Osinowo, Molokwu & Osori (1981) and would appear to result from asymmetrical growth of the testes. Although the testicular weight (paired sides) of the Sokoto Gudali is significantly higher than that of the Bunaji, it appears, however, not necessarily to be accompanied by a higher rate of sperm production. The high correlation coefficient observed between the scrotal circumference and the testicular weight, testicular spermatids and caudae epididymides in both bulls is in accord with the observations of Osinowo et al. ( 1981). Testicular size is an heritable trait and it would be desirable to select animals with large testicular sizes on the basis of the above correlative relationships, especially ifit is accompanied by semen of high quality. The testicular and epididymal sperm reserves recorded for the Bunaji and Sokoto Gudali bulls are lower than those reported for temperate breeds (Almquist & Amann, !961; MacMillan & Hafs, 1968). The time divisor used to convert testicular spermatid/spermatozoa to daily sperm production was 5·32 (Amann et al., 1976). In both the Bunaji and the Sokoto Gudali bulls the daily sperm production of4·!5 X 109 and 3·57 X 109 respectively was lower than the 7·5 X 10 9 reported for dairy bulls in temperate zones (Amann et al., 1976). This study shows that in Bunaji and Sokoto Gudali bulls, the caudae epididymides constitute the major sperm storage area. The caudal epididymal spermatozoa (paired sides) of9·91 ± 0·77 X 10 9 in the Bunaji would represent an accumulation of2·39 days' production and in the Sokoto Gudali, with much bigger caudae epididymides, the sperm reserve of 14-60 ± 1·69 X !09 would represent 0·2 days production. KumiDiaka, Osori & Nagaratnam ( 1980) observed a monthly average of0·56 X I 0 9 cells/ml in the semen of Sokoto Gudali buiJs on range. It would appear, therefore, that with adequate sexual preparation during semen collection, the mature Sokoto Gudali bull could be ejaculated 18 times before exhaustion of the caudal epididymal reserves. Further comparative studies with Friesian bulls and their male offspring from indigenous cows under tropical humid conditions should provide more information on the reproductive capacity of these bulls and a rational basis for their use in artificial insemination programmes.
ACKNOWLEDGEMENTS
The authors gratefuiJy acknowledge the help from the Department of Biochemistry, University of Nigeria, Nsukka for supplying the Triton X-100 used for this project. REFERENCES ALMQUIST,]. 0. & AMANN, R. P. (1961) . joumal of Dairy Science 44, 1668. AMANN, R. P., KAVANAUGH,]. F., GR!EL, L. C.jR & VOGLMAYR,j. K. (1974).Joumal
of Dairy Science 57, 93. AMANN, R. P., jOHNSON, L., THOMPSON, D. L. jR & PICKETT, B. W. (1976). Biology of Reproduction 15, 586. IGBOELI, G. & RAKHA, A.M. (!971).Journal of Reproduction and Fertility 25, 107.
490
BRITISH VETERINARY JOURNAL, 139, 6
KUMI-OIAKA,j., OSORI, D. & NAGARATNAM, U. (1980). British Veterina7J•Joumall36, 222. MACMILLAN, K. L. & HAFS, H. D. (1968).Joumal of Animal Science 27, 697. OSINOWO, D., DENNIS, S.M., OSORI, D. I. K . & MOLOKWU, E. C. I. ( 1977) . NigerianJoumal
of Animal Production 4, 36. OSINOWO, D. A., MOLOKWU, E. C. I. & OSORI, D. I. K . (1981) . Journal of Animal Production and Research l, 55. (AccejJted for publication 15 January 1983)
ANNOUNCEMENTS
MODELLING AND SIMULATION FOR SAFETY AND RISK ASSESSMENT
-an alternative to animal experimentation? An international seminar on this subject is being organized by Information Transfer International. The seminar will be held at the Royal College of Physicians, London, between 4 and 6 December 1983. The following subjects are likely to be in the programme: mathematical modelling of physiological processes, pharmacokinetics modelling, quantitative analysis of structure/activity relationships, quantum chemistry and modelling of drug design, estimation of toxicological endpoints. Further information may be obtained from Information Transfer International, P.O. Box 62, Beaconsfield, Bucks, HP9 2NY, England.
INTERNATIONAL SOCIETY FOR ANIMAL HYGIENE
The 5th Congress of the International Society for Animal Hygiene will be held from I 0 to 13 September 1985 at the Veterinary School in Hannover, West Germany. Details of the Congress may be obtained from: Prof. Dr D. Strauch, U niversitat Hohenheim -460, Postfach 700562, D- 7000 Stuttgart 70.
SCROTAL CIRCUMFERENCE, DAILY SPERM PRODUCTION AND EPIDIDYMAL SPERMATOZOA OF THE INDIGENOUS BUNAJI AND SOKOTO GUDALI BULLS IN NIGERIA
Bv C.
SALAU DAuou AND
V.
SHOYINKA
Department of Veterinary Surgery and Obstetrics and Department of Veterinary Microbiology and Pathology, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria.
SUMMARY
Testicular and epididymal tissues were obtained from 10 Bunaji and 10 Sokoto Gudali bulls aged four to five years. Testicular weights (paired sides) were 298·71 ± 12·55 and 412·24 ± 14·94 g for the Bunaji and the Sokoto Gudali bulls respectively. Scrotal circumferences, as determined on live animals, were 34·12 ± 0·42 and 34·54 ± 0·65 em for Bunaji and Sokoto Gudali bulls respectively. Scrotal circumference was positively correlated to the testicular and caudal epididymal spermatozoa in both breeds. Daily sperm production was estimated to be 4·15 X 10 9 and 3·57 X 109, while epididymal transition times were 4·18 and 5·71 days for Bunaji and Sokoto Gudali respectively. INTRODUCTION
The reproductive potentials of various breeds of bulls have been well documented (Almquist & Amann, 1961; Igboeli & Rakha, 1971; Amann et al., 1974). In artificial insemination programmes information on the reproductive capacity of the bulls is essential to facilitate the detection and exploitation ofbulls ofhigh genetic potential. In Nigeria at present, Bunaji, Sokoto Gudali and Friesian bulls are used in artificial insemination programmes. However, adequate information on the sperm production rate of the indigenous bulls is not available. The present study was designed to provide information on the daily sperm production and the epididymal sperm reserves of indigenous bulls. MATERIALS AND METHODS
Ten Bunaji and 10 Sokoto Gudali bulls, aged four to five years, were used. Scrotal circumference was determined at the point of the greatest scrotal-testes complex in the live animal. Following slaughter, the genital tract was removed; the testes and
BRITISH VETERINARY JOURNAL, 139,6
488
epididymides were removed from the tunics and unwanted connective tissues. The tract was then separated into testes and caput, corpus and cauda epididymides, and weighed. The right and left sides of these portions were treated separately. Each testis was homogenized for I min in a normal saline solution containing 0·05% Triton X-1 00 (v/v). The caudae epididymides were each similarly homogenized for 2 min. The volume of the homogenate was determined and emptied into a conical f1ask containing known quantity of 0·17% saponin in 0·5% formalin solution as a preservative. The final volume of the homogenate used for counting was determined and recorded. Counting was done haemocytometrically on the day of homogenate preparation and 24 h later. Each homogenate sample was counted four times and the mean recorded . The results were analysed statistically. RESULTS
The results arc presented in Table I. Scrotal circumference was positively correlated to the paired testicular weight (r = 0·96), testicular spermatids/spermatozoa (r = 0·84) and the caudal epididymal spermatozoa (paired sides) (r = 0·88) for the Sokoto Gudali bulls and for the Bunjai bulls (r = 0·91, r = 0·87 and r = 0·89 respectively). Testicular weight (paired sides) was significantly (P<0·05) greater in the Sokoto Gudali compared to the Bunaji bulls . In both groups of bulls the right testes were significantly heavier than the corresponding left testes. This asymmetry was not observed in the other paired reproductive structures. However, the caudae epididymides (paired sides) of the Sokoto Gudali were significantly (P<0·05) heavier than those of the Bunaji, and the caudal epididymal sperm reserves (paired sides) were significantly (P
REPRODUCTIVE PARAMETERS OF 10 BUNAJI AND 10 SOKOTO GUDALI BULLS IN NIGERIA
Parameters
Scrotal circumference em Testicular weight (paired sides) g Epididymides (paired sides) Caputg Corpus g Caudag Sperm reserves X I 09 Testes (paired sides) Epididymal sperm reserves X 109 Caput Corpus Cauda Daily sperm production X I 0 9 (time divisor 5·32) Epididymal transit time days
Bunaji bulls
Sokolo Gudali bulls
34·12:!: 0·42 398· 71 :!: 12·55
34·54:!: 0·65 412·24 ± 14·94
24-85 :!: 2·42 8·57 ± 1·06 18·76:!: 2·97
23·81 :!: 2·04 4·61 :!: 0·47 25·7 ± 2·60
22·06:!: 2·78
19·02:!: 2-47
5·05:!: 0·83 2·48:!: 0·14 9·91 :!: 0·77 4·15
5·50:!: 1·09 I ·25 :t 0· 1 I 14·60 ± 1·69 3·57
4·18
5·71
REPRODUCTION PARAMETERS IN NIGERIAN BULLS
489
DISCUSSION
The scrotal circumference observed in the present study for the Bunaji and the Sokoto Gudali falls within the range earlier reported for these bulls (Osinowo et al., 1977). The testicular asymmetry observed was also recorded by Osinowo, Molokwu & Osori (1981) and would appear to result from asymmetrical growth of the testes. Although the testicular weight (paired sides) of the Sokoto Gudali is significantly higher than that of the Bunaji, it appears, however, not necessarily to be accompanied by a higher rate of sperm production. The high correlation coefficient observed between the scrotal circumference and the testicular weight, testicular spermatids and caudae epididymides in both bulls is in accord with the observations of Osinowo et al. ( 1981). Testicular size is an heritable trait and it would be desirable to select animals with large testicular sizes on the basis of the above correlative relationships, especially ifit is accompanied by semen of high quality. The testicular and epididymal sperm reserves recorded for the Bunaji and Sokoto Gudali bulls are lower than those reported for temperate breeds (Almquist & Amann, !961; MacMillan & Hafs, 1968). The time divisor used to convert testicular spermatid/spermatozoa to daily sperm production was 5·32 (Amann et al., 1976). In both the Bunaji and the Sokoto Gudali bulls the daily sperm production of4·!5 X 109 and 3·57 X 109 respectively was lower than the 7·5 X 10 9 reported for dairy bulls in temperate zones (Amann et al., 1976). This study shows that in Bunaji and Sokoto Gudali bulls, the caudae epididymides constitute the major sperm storage area. The caudal epididymal spermatozoa (paired sides) of9·91 ± 0·77 X 10 9 in the Bunaji would represent an accumulation of2·39 days' production and in the Sokoto Gudali, with much bigger caudae epididymides, the sperm reserve of 14-60 ± 1·69 X !09 would represent 0·2 days production. KumiDiaka, Osori & Nagaratnam ( 1980) observed a monthly average of0·56 X I 0 9 cells/ml in the semen of Sokoto Gudali buiJs on range. It would appear, therefore, that with adequate sexual preparation during semen collection, the mature Sokoto Gudali bull could be ejaculated 18 times before exhaustion of the caudal epididymal reserves. Further comparative studies with Friesian bulls and their male offspring from indigenous cows under tropical humid conditions should provide more information on the reproductive capacity of these bulls and a rational basis for their use in artificial insemination programmes.
ACKNOWLEDGEMENTS
The authors gratefuiJy acknowledge the help from the Department of Biochemistry, University of Nigeria, Nsukka for supplying the Triton X-100 used for this project. REFERENCES ALMQUIST,]. 0. & AMANN, R. P. (1961) . joumal of Dairy Science 44, 1668. AMANN, R. P., KAVANAUGH,]. F., GR!EL, L. C.jR & VOGLMAYR,j. K. (1974).Joumal
of Dairy Science 57, 93. AMANN, R. P., jOHNSON, L., THOMPSON, D. L. jR & PICKETT, B. W. (1976). Biology of Reproduction 15, 586. IGBOELI, G. & RAKHA, A.M. (!971).Journal of Reproduction and Fertility 25, 107.
490
BRITISH VETERINARY JOURNAL, 139, 6
KUMI-OIAKA,j., OSORI, D. & NAGARATNAM, U. (1980). British Veterina7J•Joumall36, 222. MACMILLAN, K. L. & HAFS, H. D. (1968).Joumal of Animal Science 27, 697. OSINOWO, D., DENNIS, S.M., OSORI, D. I. K . & MOLOKWU, E. C. I. ( 1977) . NigerianJoumal
of Animal Production 4, 36. OSINOWO, D. A., MOLOKWU, E. C. I. & OSORI, D. I. K . (1981) . Journal of Animal Production and Research l, 55. (AccejJted for publication 15 January 1983)
ANNOUNCEMENTS
MODELLING AND SIMULATION FOR SAFETY AND RISK ASSESSMENT
-an alternative to animal experimentation? An international seminar on this subject is being organized by Information Transfer International. The seminar will be held at the Royal College of Physicians, London, between 4 and 6 December 1983. The following subjects are likely to be in the programme: mathematical modelling of physiological processes, pharmacokinetics modelling, quantitative analysis of structure/activity relationships, quantum chemistry and modelling of drug design, estimation of toxicological endpoints. Further information may be obtained from Information Transfer International, P.O. Box 62, Beaconsfield, Bucks, HP9 2NY, England.
INTERNATIONAL SOCIETY FOR ANIMAL HYGIENE
The 5th Congress of the International Society for Animal Hygiene will be held from I 0 to 13 September 1985 at the Veterinary School in Hannover, West Germany. Details of the Congress may be obtained from: Prof. Dr D. Strauch, U niversitat Hohenheim -460, Postfach 700562, D- 7000 Stuttgart 70.