CORRELATION BETWEEN SCROTAL CIRCUMFERENCE, AGE AND LIVE BODY WEIGHT IN RED SOKOTO AND WEST AFRICAN DWARF BUCKS

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1 Vom Journal of Veterinary Science Vol. 10, 2015: CORRELATION BETWEEN SCROTAL CIRCUMFERENCE, AGE AND LIVE BODY WEIGHT IN RED SOKOTO AND WEST AFRICAN DWARF BUCKS OBANDE, G.E., DAWUDA, P.M., OYEDIPE, E.O. AND ODEH, S. Department of Veterinary Surgery and Theriogenology, College of Veterinary Medicine, University of Agriculture, PMB 2373, Makurdi, Benue State, Nigeria *Correspondence: ; SUMMARY Age, live body weight and scrotal circumference were obtained from 221 bucks (99 Red Sokoto and 122 West African Dwarf) between 3 months and 27 months of Age. The live bodyweight of bucks was measured by taking the weight of the observer first and then the live body weight of the animal was taken by the observer carrying the buck and standing on a weighing scale. The difference between the weight of the observer when carrying the buck and that of the observer alone gave the weight of the buck in kilogram. Scrotal circumference was measured by grasping the scrotum but not the neck of the scrotum to avoid distracting the testes then using two fingers to push the testicles ventrally to eliminate any wrinkles and for both testes to be held at the same level. A measuring tape (Model: DSP-0080) was passed around the scrotum and tightened at the greatest width of the two testicles and measured in centimeters when the buck was relaxed. Age estimates were carried out by examination of the presence or absence of temporary and permanent incisors and the degree of tear and wear of the molars.red Sokoto goats had significant (p<0.05) higher live body weight and scrotal circumference than West African Dwarf. Within breeds, there was a linear relationship between age, live body weight and scrotal circumference. As age increased, live body weight and scrotal circumference also increased.scrotal circumference had the highest significant correlation coefficient (0.94 and 0.88) with live body weight in both Red Sokoto and West African Dwarf bucks, respectively. Consequently, scrotal circumference in both breeds of goats was the best single predictor of live body weight (R²=0.889 and 0.858) for Red Sokoto and West African Dwarf, respectively. Therefore, in conclusion the current study has demonstrated that both live body weight and scrotal circumference are better in determining age in Red Sokoto bucks than in West African Dwarf bucks. Keywords: Scrotal circumference, age, live body weight, Red Sokoto bucks, West African Dwarf bucks INTRODUCTION Live body weight is often the most common and informative measure of animal reproductive performance (Adeyinka and Mohammed, 2006) which is often unavailable to goats producers working with animals under field conditions in Nigeria (Raji et al., 2008). Decision making on the field is sometimes difficult and husbandry techniques like animal medication are usually based on questionable and subjective estimates of body weight. Similarly, subjective 127

2 Obande et al: Correlation Between Scrotal Circumference, Age and Live Body Weight estimates using dentition for ageing can lead to inaccurate aging of animals and hence a false indication of age estimation especially at puberty. Research findings have shown that there is a relationship between age, live body weight and semen characteristics and fertility traits in goats. However, Researchers have indicated that scrotal circumference is one of the most heritable components of fertility in ruminants and should be included in the breeding soundness examination (Al- Ghalban et al., 2004; Blood et al., 2007). Since local producers may not be in a position to test ejaculate quality and quantity of males before using them for breeding, a procedure that would link external testicular measurements with sperm output will provide a good guide to breeding soundness (Peter and Lesile, 1980; Palasz et al., 1994; Agunwamba and Mecha, 1982; Ogwuegbu et al., 1985). Testicular size or the amount of sperm producing tissue is estimated through the use of scrotal circumference. This is because there is a high correlation between scrotal circumference and sperm output (Bitto et al., 2008; Willett and Ohm, 1957). Scrotal circumference measurements can be a valuable tool in making sire selection decisions because scrotal circumference has been shown to favorably relate to growth rate and live body weight from birth to adulthood (Neely et al., 1982; Knights et al., 1984; 1988; Bourdon and Brinks, 1981; Lunstra et al., 1988; Smith et al., 1989). Therefore, a correlation between scrotal circumference, age and live body weight may serve as the basis for using scrotal circumference instead of using age and live body weight estimates to predict fertility traits under field conditions in both West African Dwarf and Red Sokoto goats. Hence the objectives of the current study are (i) to determine scrotal circumference and its relationship with age and live body weight of West African Dwarf bucks in Nigeria, (ii) to determine scrotal circumference and its relationship with age and live body weight of Red Sokoto bucks in Nigeria, (iii) to establish whether scrotal circumference is a useful predictor for age and live body weight in both Red Sokoto bucks and West African Dwarf bucks. MATERIALS AND METHODS Location of the experiment This study was conducted in Makurdi, Benue State, Nigeria. Makurdi is located in North Central Nigeria on longitude 8 0 and 9 0 E, and latitude 9 0 and 8 0 N.Rainfall distribution and temperature range between millimeter and C, respectively. Data collection methods One hundred and twenty-two West African Dwarf (122) and ninety nine (99) Red Sokoto bucks were sampled from the International Cattle Market, North Bank, Makurdi. The experiment was conducted for a period of two (2) months (from 6 th September 2012 to 12 th of November 2012). Live body weight was measured using a weighing balance (Model: H89 DK BLUE). The live bodyweight of the bucks was measured in kilograms by following the procedure as described by Akpa et al. (1998). The weight of the observer was taken first and then the live body weight of each buck was taken by the observer carrying the buck and standing on a weighing scale. The difference between the weight of the observer carrying the buck and that of the observer alone gave the weight of the buck in kg (PLATE I).Scrotal circumference was measured by grasping the scrotum but not the neck of the scrotum to avoid distracting the testes

3 Vom Journal of Veterinary Science Vol. 10, 2015: (Ott 1986; Memon et al., 2007) then using two fingers to push the testicles ventrally to eliminate any wrinkles and for both testes to be held at the same level. A measuring tape (Model: DSP-0080) was passed around the scrotum and tightened at the greatest width of the two testicles and measured in centimeters (Adedeji and Gbadamosi, 1999; Ahmed, et al, 2005) when the buck was relaxed. This was easily done with the buck standing (PLATE II). Age estimates were carried out by examination of the presence or absence of temporary and permanent incisors and the degree of tear and wear of the molars (PLATE III). Sample analysis The mean (X) and the standard error of the mean (± s.e.m) were determined for each parameter. Correlations (Pearson s correlation coefficients) between scrotal circumference, live body weight and age were computed within each breed of goats. The choice of best fitted regression model was selected using coefficient of determination (R²). Pearson s correlation coefficients were calculated to determine the correlation or relationship between live body weight, age and testicular parameters. Regression equation and Coefficient of determination (R²) were developed to determine the proportion of variance between scrotal circumference and live body weight. PLATE I. Proceeding of weighing bucks PLATE II. Measurement of scrotal circumference PLATE III. Ageing of bucks using dentition RESULTS Live body weight and scrotal circumference of Red Sokoto and West African Dwarf bucks at various ages are presented in Table I. Within breeds, live body weight was significantly (P<0.05) higher in bucks aged 27 months than those between 15 months and months. Also weight was significantly higher (P<0.05) in bucks aged months than those 15.Fig.Ishows the comparison between live body weight of Red Sokoto and West African Dwarf bucks at age 15 months, months and months. There was no significant (p>0.05) difference between the two breeds. Fig. II shows the comparison between scrotal circumference of Red 129

4 Obande et al: Correlation Between Scrotal Circumference, Age and Live Body Weight Sokoto and West African Dwarf bucks at 15 months, months and months. There was no significant (P>0.05) difference between the two breeds. The correlation coefficients indicating the relationship between live body weight, age and scrotal circumference are shown in Table II. Live body weight and scrotal circumference had the highest correlation coefficients of 0.94 and 0.88 for both Red Sokoto and West African Dwarf bucks respectively, this is highly significant (P<0.01). The correlation coefficient between live body weight and age was 0.93 and 0.79 for both Red Sokoto and West Africa Dwarf bucks respectively. This was significant (P<0.01) for both Red Sokoto and West Africa Dwarf bucks. The correlation coefficient between scrotal circumference and age was 0.93 and 0.79 for both Red Sokoto and West African Dwarf respectively. This was significant (P<0.01) for both Red Sokoto and West Africa Dwarf bucks. Fig. III shows a regression equation and coefficient of determination(y=0.299x+14.20; R²=0.889)between live body weight and scrotal circumference of Red Sokoto bucks. The R² (0.889) was highly significant (P<0.01).Fig. IV shows a regression equation and coefficient of determination (y=0.336x+12.04; R²=0.858) between live body weight and scrotal circumference of West Africa Dwarf bucks. The R² (0.889) was highly significant (P<0.01). ± TABLE I. Mean (X ± s.e.m) live body weight and scrotal circumference of West African Dwarf and Red Sokoto bucks. Breed Age (months) Total no Live body Scrotal of bucks weight (kg) circumference (cm) Red Sokoto bucks e c a West African Dwarf bucks f d b P-Value Means in the same column with different superscripts differ significantly (P<0.05)

5 Vom Journal of Veterinary Science Vol. 10, 2015: TABLE II.Correlation coefficient between live body weight, age and scrotal circumference in Red Sokoto and West African Dwarf bucks. Correlation Matrix for Red Sokoto Buck Live body Age Live body Weight Weight 0.933*** Scrotal circumference 0.929*** 0.943*** Cell contents: Pearson correlation P-value (1) Correlation Matrix West African Dwarf Live body Age Live bodyweight Weight 0.785*** Scrotal circumference 0.785*** 0.882*** Cell contents: Pearson correlation P-value (1) FIGURE I. Comparison of live body weight between Red Sokoto and West African Dwarf bucks aged between 3 and 27 months. There was no significant difference between breeds (p>0.05) 131

6 Obande et al: Correlation Between Scrotal Circumference, Age and Live Body Weight FIGURE II. Comparison of scrotal circumference of Red Sokoto and West African Dwarf bucks between 3and 27 months. There was no significant difference between breeds (p > 0.05). FIGURE III. The Regression equation and coefficient of determination (R²) for scrotal circumference in Red Sokoto bucks

7 Vom Journal of Veterinary Science Vol. 10, 2015: FIGURE IV. The regression equation and coefficient of determination (R²) for scrotal circumference in West African Dwarf bucks DISCUSSION The results of this study which shows a linear relationship between live body weight, scrotal circumference and age is in agreement with the previous finding of Land et al. (1982). Thus, as body weight and age increase, scrotal circumference also increase in both Red Sokoto and West African Dwarf bucks. Bilaspuri and Singh (1993) also reported that testicular measurements increase with age and live body weight in Saneen and Jumnapari goats in Malaysia. Adedeji and Gbadamosi (1999) reported scrotal circumference of 22.6cm at 24months of age and body weight of 26kg for Red Sokoto bucks. These values are similar to those of Red Sokoto bucks of 22cm and 26kg for scrotal circumference and live body weight, respectively at 24 months of age reported in the current study.the results of the present study is in agreement with the report of Raji et al. (2008) and Adedeji and Gbadamosi (1999) who reported similar body weight of 26kg and 25.5kg respectively for Red Sokoto bucks at 24 months of age. Higher body weight had also been reported by Hamayun et al. (2006) and Fida et al. (2006) at comparable age group in other breeds of goats. This study has shown that there is a wide variability in live body weight and scrotal circumference measurements at all ages (Table I). This is especially so with live bodyweight which is in agreement with earlier reports (Hamayun et al., 2006; Fajemilehin and Salako, 2008) in goats. Ebegbulem et al. (2011) reported live body weight of 13.46±0.54 kg for West African Dwarf bucks at 12months while Okpeku et al. (2011) reported kg live body weight on West African Dwarf bucks at 12 months. Their observation is similar to the live body weight observed in the current study (15.87±0.91kg) at 15 months. This variability in live body weight among different studies could be due to individual differences in genetic composition, nutrition and environmental 133

8 Obande et al: Correlation Between Scrotal Circumference, Age and Live Body Weight or management style. The above reasons could be the cause(s) of this variability in live body weights recorded in these various studies. Bucks in this market were brought for sale from different production systems ranging from semi-intensive to extensive. This could affect live weight of bucks that are at the same age group. Another reason for variability of results especially age could be as a result of subjective ageing using dentition. Adedejiand Gbadamosi (1999) reported correlation coefficient of 0.94 between live body weight and scrotal circumference for Saneen and Jamnapuri goat crosses. The current study which shows a correlation coefficient of 0.94 between live body weight and scrotal circumference is in agreement with these reports observed in bulls (Coulterand Foote, 1979), rams (Braun et al., 1980) and Buffalo (Bongso et al., 1984).The highly positive and significant correlation between live body weight, age and scrotal circumference in the current study suggests that either of these variables or their combinations could provide a good estimate for predicting reproductive functions such as puberty, libido, semen output and possibly fertility of these breeds. Coulter and Foote (1977) were of the view that correlation between live body weight and scrotal circumference often ignored the considerable influence of age and suggested that males with larger testis may readily possess larger body size as a result of anabolic effect of androgens. Therefore the observation of Coulter and Foote (1977) is worthy of consideration when interpreting or using these correlations. The coefficient of determination R² indicated that scrotal circumference accounts for 88% in Red Sokoto bucks and 85% in West African Dwarf bucks in predicting live body weight. The R² values obtained from the regression analysis of this study shows that scrotal circumference was reliable in predicting body weight at any age ( 15months and 27months). Raji et al. (2008) reported R² values for scrotal circumference of 51.7% in Red Sokoto goats which is lower than that obtained from this study. The difference could be attributed to the plane of nutrition, management practices and variation in climatic conditions. CONCLUSION The high and positive correlations between live body weight, age and scrotal circumference in this study suggest that we may use any of these parameters to reliably predict reproductive status of the bucks in both Red Sokoto and West African Dwarf goats. However, scrotal circumference was the most reliable predictor. Where there is difficulty in predicting the age of bucks accurately using dentition, the measurement of the scrotal circumference and/or live body weight can be used to predict age of bucks and their reproductive status. Scrotal circumference has an overarching beneficial effect over live body weight in determining age in these breeds because it is more user friendly than live body weight which is highly subjective, cumbersome, needs a weighing scale and needs subtracting between the weight of the observer and that of the observer plus buck in order to get that of the buck. This can introduce unnecessary errors in the result (i.e. the substantive weight of the buck). Recommendation Measurement of scrotal circumference early in life of bucks should be incorporated into the Breeding Soundness Examination System (BSES) for Red Sokoto and West African Dwarf bucks in order to

9 Vom Journal of Veterinary Science Vol. 10, 2015: aid early selection of genetically superior breeding males. This will afford the farmer the opportunity to properly feed and manage all selected breeding bucks in a manner so as to maximize their genetic potentials early before they are sexually matured for breeding. REFERENCES 1. Adedeji, O.S. and Gbadamosi, A.J. (1999). Relationship of scrotal circumference to age, body weight, the right and left scrotal length in the red Sokoto goats. In: Proceedings of 26 th Annual Conf. NSAP March, Ilorin, Nigeria, pp: Adeyinka, I.A. and Mohammed, I.D. (2006). Relationship of live body weight and linearbody measurements in two breeds of goats of Northern Nigeria. J. Anim. Vet.Adv., 5 (11): Agunwamba, C.C. and Mecha, I. (1982).Classification of goats in Southern Nigeria (WAD goats). Proc.3 rd International Conference on Goat production and Diseases. Arizona. pp Ahmad, N. and Noakes, D.E. (1996.) Seasonal variation in the semen quality of young Britishgoats. Br. Vet. J. 152: Ahmed, A., Babiker, A., Gubartallal, A., Kamal, A. and Bakhiet, O. (2005). Comparative Studies on reproductive performance of Nubian and saanen bucks under the climatic conditions of Khatoum. J. Anim. Vet. Adv., 4: Al-Ghalban, A.M., Tabbaa, M.J., Kridli, R.T. (2004).Factors affecting semen characteristics and scrotal circumference in Damascus bucks. Small Ruminant Research; 53: Akpa, G.N., Duru, S. and Amos, T.T. (1998). Influence of strain and sex on estimation of within-age group body measurements. Tropical Agriculture, Trinidad. 75: Bilaspuri, G.S. and Singh, K. (1993). Distinction between Malabari and Beetal goat breeds. Small Ruminant Research. 10: Bitto, I.I., Egbunike, G.N. and Akusu, M.O. (2008).Seasonal variations in morphometric characteristics of the pubertal West African Dwarf bucks in native tropical environment. Int. J. Morphol., 26 (2): Blood, D.C., Studdert, V.P. and Gay, C.C. (2007). Saunders Comprehensive Veterinary Dictionary.3rd ed. page Bongso, T.A., Jainudeen, M.R. and Sitizahrah, A. (1982).Relationship of scrotal circumference to age, body weight and onset of spermatogenesis in goats. Theriogeniology. 18(5): Bongso, T.A., Hassan, M.D. and Novelin, W. (1984).Relationship of scrotal circumference and testicular volume to age and body weight in swamp buffalos. Theriogenology. 22: Bourdon, R.M and Brinks, J.S. (1981). Scrotal circumference in yearling Hereford bulls: Adjustment factors, heretabilities and genetic environmental and phenotypic relationships with growth traits. J. Anim. Sci. 62:pp Braun, W.F., Thompson, J. M. and Ross, C.V. (1980). Ram scrotal circumference measurements. Theriogeniology. 13: Coulter, G.H. and Foote, R.H. (1977).Relationship of body weight to testicular size and consistency in growing Holstein bulls. Anim. Sci. 44: Coulter, G.H. and Foote, R.H. (1979).Bovine testicular measurement as an indicator of reproductive performance and their relationship to productive trait in cattle.areview. Theriogenology. 11: Ebegbulem, V.N., Ibe, S.N., Ozung, P.O. and Ubua, J.A. (2011). Morphometric trait characteristics of West African Dwarf goats in Abia state, South East Nigeria. Continental Journal of Agricultural Science. 5(2): Fajemilehin, S. and Salako, A.E. (2008). Body measurement characteristics of the West African Dwarf Goats in deciduous forest zone of southern Nigeria. African Journal of Biotechnology. 7 (14):

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