Semen characteristics of Muturu Bulls — Bos brachyceros

THERIOGENOLOCY Bos brachyceros SEMEN CHARACTERISTICSOF MUTURU BULLS - B.I. Orji, G. Igboeli and L.N. Nwakalor Departmentof Animal Science Universityof Nigeria Nsukka, Nigeria Received for publication: January 30, 1984 Accepted: May 22, 1984 ABSTRACT Six mature Muturu Bulls were elecroejaculatedonce a week for nine weeks to study their semen quality and ejaculate characteristic / The semen volume was 1.8 ml + 0.1, the sperm concentration2.16 x 108. ml + 0.29, and the progressivesperm motility 36.2% + 2.6. Morpho1ogTcallynormal sperm averaged 70.0% + 3.1, primary-abnormalities 13.4% + 1.0 and secondaryabnormalities15.1% + 2.3. Except in one bull, no measurablelevels of fructosewere obzerved. The contents of major cations and chloride ions in whole semen and seminal plasma were also determined. Keywords: Semen, characteristics,Muturu, bulls. INTRODUCTION The Muturu is a small unimprovedhumpless shorthornbreed of cattle, indigenousto the southern forest zones of West Africa. The breed stands about 90 to 105 cm at withers, weighs 100 to 120 kg at maturity and has a scrotal circumferenceof 5.9 to 7.9 cm. Among its attributesare its hardiness and apparent toleranceto trypanosomiasis. At present, this breed of cattle, which in the rainforestzones of West Africa has a high socio-traditionalvalue, may be facing possible extinctionunless a programmeof breeding improvementis initiated. A series of studies was thereforeinitiatedto characterizethe sexual behaviourof Muturu bulls (I). The present study is a follow-upaimed at evaluatingsemen characteristicsof these bulls. MATERIALS AND METHODS The study was conductedfor nine weeks during the late dry season (Januaryto March). This period is characterizedby low rainfall (34.1 mm), high environmentaltemperatures(27.4OC),low relative humidity (54.5%)and scanty pastures and vegetation.

Acknowledgements This study was supportedby the Senate Research Grant No. 00238/76 of the Universityof Nigeria, Nsukka, to which we express our immense gratitude. We are also grateful to Messrs A.M. Allam, B.O. Nwegbu, S.C. Adimonye,U.M. Kalu and the laboratorystaff of the Departmentof Animal Science, Universityof Nigeria, for their assistance. AUGUST 1984 VOL. 22 NO. 2

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Six mature Muturu bulls whose history and managementhave been previouslydescribed (1) were electroejaculated once weekly followinga two-week pre-experimentalperiod. Before each semen collection,the bulls were led singly into a crush; the prepuce was washed with soap and water, rinsed with clean water and dried thoroughly. The preputialhairs were trimmed as necessary. The bulls were electroejaculatedwith a rectal probe using a Standard PrecisionElectronicsejaculator (StandardPrecisionElectronics, Inc. Colorado, U.S.A.) after stimulatoryerection. The semen was collectedin a prewarmedcovered collectiontube. After collection,each ejaculatewas examined for volume, progressivemotility, concentrationand morphology. The sperm concentrationwas determinedby the photometricmethod (2). Duplicate were used for smears of each ejaculate,stained with.nigrosin/eosin, the classificationof sperm morphology. One hundred sperm cells were classifiedfrom each smear. Following initial processingas describedabove, whole semen collectedduring weeks 1, 3, 5, 7 and 9 was pooled for each bull and stored frozen at -20°C until analyzed for fructose,calcium, magnesium, sodium, potassiumand chloride ions. Whole semen collectedduring weeks 2, 4, 6 and 8 was centrifugedat 15,000$ and 5OC, similarlypooled and stored, and similarlyanalyzed. Pooling was considerednecessary to accumulatesufficientvolumes of both whole semen and seminal plasma for biochemicalanalyses. Fructose concentrationwas determinedaccording to Mann (3) and chloride concentrationaccording to modified proceduresof Lisk (4); both determinationswere done with Cecil CE 303 Spectrophotometer, Cecil Instruments,Cambridge,England. Sodium and potassium concentrationswere determinedby means of a flame photometerand magnesium and calcium by the Atomic AbsorptionSpectrophotometer, Pye Unicam Ltd., Cambridge,England (5, 6, 7). The means and their standard errors were computed and analysis of variance was used to determinethe effects of bulls and weeks of collectionin accordancewith the methods of Snedecor and Cochran (8). Student's t-test was also used to compare the mean cation and chloride contents of whole semen and seminal plasma. The relationship between the various semen characteristicswas examined by simple correlations. RESULTS A total of 50 out of 54 expected ejaculateswere collectedfrom the bulls and the means of the ejaculatecharacteristicsare presentedin Table 1. The semen volume was 1.8 + 0.1 ml. Ejaculate volume between bulls did not differ significanTly. The percent of progressive sperm motility averaged 36.2 + 2.6. The estimate of percent of progressivesperm motility was significantlyaffected by bulls (P/0.05)but not by the weeks of collection. The mean sperm AUGUST

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THERIOGENOLOGY concentrationwas 2.16 + 0.29 x 108/m1. No significantdifference was found between the mean sperm concentrationof the ejaculates the bulls. The total sperm output/ejaculatewas 3.95 -+ 0.62 x 10if . Table 1: Ejaculate characteristicsof Muturu bulls Parameter

Mean

Range

Volume (ml)

1.8 + 0.1

0.4-5.0

Motility (%)

36.2 + 2.6

0.0-70.0

Sperm cone/ml (~10~)

2.16 + 0.29

trace-6.58

Sperm output/ejac (~10~)

3.95 + 0.62

0.88-7.02

Normal sperm morphology (%)

70.0 + 3.1

6.0-98.0

Head (%)

4.1 2 0.4

0.0-12.0

Midpiece (%)

4.2 + 0.7

0.0-24.0

Tail (%I

5.1 + 0.5

0.0-13.0

15.1 f 2.3

0.0-75.0

Primary sperm abnormality:

Secondaryabnormality (%)

The average morphologicallynorma- spermatozoain the ejaculate was 70.0% + 3.1, with significantdifferencesbetween bulls (PLO.05).-The average percentageof primary abnormalitieswas 13.4% made up as follows: 5.1% + 0.5, tail; 4.2% + 0.7, midpiece; and 4.1% + 0.4, head. However, no-significantdifferenceswere found Between bulls and between weeks of collectionfor primary abnormalities,except for the effect of weeks on the midpiece abnormality (PLO.05). The percent of secondaryabnormalitiesshowed no significantdifferencebetween bulls and between weeks. Tailless, coiled, and broken-tailspermatozoaas well as spermatozoawith protoplasmicdroplets were the most frequent secondary abnormalitiesobserved. The fructose,major cations and chloride contents of whole semen (WS) and seminal plasma (SP) of the bulls are presented in Table 2. Only one of the bulls had positive fructose content, with a concentration of 337.5 mg/lOO ml for WS and 262.5 mg/lOO ml for SP. There were no significantdifferencesbetween the major cations and between the chloride ion contents of WS and SP. Sodium:potassiumratio in WS was 1.08:1 and in SP 1.23:1. The correlationcoefficientsbetween individualcations and chloride contents in WS and SP (Table 3) indicate that sodium and chloride contents in WS were significantlycorrelated (P/0.05). The correlationcoefficientsbetween sodium, Calcium, ma@eSlum, Potassium and chloride ion contents in WS and SP were not significant.

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1.9-8.7 3.3-7.0 250.0-433.3

4.8 + 1.0 4.8 + 0.6 330.7 2 33.7

2.4-8.9 1.8-7.0 210.0-413.0

4.9 + 0.8

341.7 + 29.4

Magnesium

Chloride

aBull No. 2 averaged 337.5 mg % and 262.5 mg % in the whole semen and seminal plasma, respectively, while all other bulls showed no measurable levels of fructose.

Calcium

5.9 + 1.0

239.7 2 21.0

Potassium

60.0-310.0

130.0-445.0

260.0 + 47.0

Sodium 210.0 + 43.9

Range

140.0-270.0

trace

Mean

200.0-300.0

trace

Fructosea

Range

Seminal Plasma

257.7 + 15.2

Mean

Whole Semen

Fructose, cation and chloride contents (mg/lOO ml) of Muturu bull semen

Variable

Table 2:

THERIOCENOLOCY

Table 3: Correlationcoefficientsabetween the cation and chloride contents in whole semen and seminal plasma

Calcium Magnesium

Calcium

Magnesium

(0.671b

0.36

-0.09

0.42

-0.14

(0.60)

-0.81

-0.22

-0.30

0.66

0.55

0.55

Sodium

Sodium

-0.39

-0.75

C-0.06)

Potassium

-0.40

-0.41

0.58

Chloride

-0.01

-0.44

0.86W

Potassium

Chloride

(0.50)

-0.18

0.43

(-0.69)

aWhole semen lower left of diagonal, seminal plasma upper right of diagonal. b

(

1 Refers to correlationcoefficientsbetween concentration in whole semen and seminal plasma.

*PLo.o5. DISCUSSION The most significantfindings in this study relate to the small quantity of the ejaculatevolume, the low motility and the relatively high number (approximately30%) of morphologicallyabnormal spermatozoa. The lowvolume maybe a reflectionof the small body and testicularsize of the bulls since, as indicatedin earlier publications (9, IO), sperm productionis highly positivelycorrelatedto the testis size. The sperm concentrationwhich ranges from trace to 6.58 x 108/ml,althoughbelow values previouslyreported for some tropical bulls (Ill, does suggest that with such bulls which were unselectedfor any productivefunctions,there could be improvement in the semen characteristicsthrough selectivebreeding of the animals. Notable in the biochemicalanalyses,however, was the virtual absence of seminal fructose but a well-balancedcation and chloride complex. The sodium and chloride concentrationin WS and SP (Table 2) are within the range reported in the literaturefor other bulls (12, 13). With the possible applicationof artificialinseminationfor the rapid improvementof this breed of cattle, great limitationsmay be encounteredin semen extensionand preservationbased on the values of sperm concentrationand sperm motility reported here. However, the present study, which covers only one season, represents

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THERIOGENOLOGY an.initial attempt to accumulate relevant breeding data aimed at the subsequent improvement of the breed. It will be necessary to study further the observed virtual absence of fructose content in order to determine the total metabolisable energy content of the Muturu bull semen and to determine to what extent this will constitute an impediment to sperm motility and survival. REFERENCES 1.

Nwakalor, L.N., Orji, B-1. and Igboeli, G. Sexual behaviour in Muturu, N'dama and Holstein-Friesian bulls in a humid tropical environment. Wld. Rev. Anim. Prod. -15: 35-46 (1979).

2.

Salisbury, G.W., Beck, G.H., Elliott, F.I. and Willett, E.L. Rapid methods for estimating the number of spermatozoa in bull semen. J. Dairy Sci. 6: 69-78 (1943).

3.

Mann, T. Fructose content and fructolysis in semen, Practical application in the evaluation of semen quality. J. Agric. Sci. -38: 323-331 (1948).

4.

Lisk, D.J. Rapid combustion and determination of residues of chlorinated pesticides using a modified Schoniger method. J. Agr. Food Chem. 8: 119-121 (1960).

5.

Willis, J.B. The determination of metals in blood serum by atomic absorption spectroscopy. I. Calcium. Spectrochim. Acta -16: 259-272 (1960).

6,: Willis, J.B. The determination of metals in blood serum by atomic absorption spectroscopy. II. Magnesium. Spectrochim. ,Acta -16: 273-278 (1960). 7. Quinn, P.J., White, I.G. and Wirrick, B.R. Studies of the c distribution of the major cations in semen and male accessory secretions. J. Reprod. Fert. -10: 379-388 (1965). 8. 9.

Snedecor, G.W. and Cochran, W.G. Statistical Methods, 6th ed. Iowa State University Press, Ames, Iowa, 1967, pp. 258-298. Willett, E.L. and Ohms, J.I. Measurement of testicular size and its,relation to production of spermatozoa by bulls. J. Dairy _,Sci.,40: 1559-1569 (1957). -

10.

Nwakalor, L.N. and Orji, B.I. Testicular size and sperm output in Holstein-Friesian and N'dama bulls. Nig. J. Anim. Prod. 9: (in press, 1982).

11.

Igboeli, G. and Rakha, A.M. Ejaculation and ejaculate characteristics of Angoni (short-horn Zebu) bulls. J. Reprod. Fert. -26: 183-187 (1971).

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12. Mann, T. The Biochemistry of Semen and of the Male Reproductive Tract. Methuen & Co. Ltd., London. 1964, pp. 94-100. 13. Igboeli, G. and Rakha, A.M. Major cations in the semen of Angoni (short-horn Zebu) bulls. J. Reprod. Fert. -24: 377-381 (1971).

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