Introduction

Boer goat (Capra hircus) is considered as one of the largest desirable goat breed for chevon production. Boer breed is well known worldwide for superior body conformation, high FCR, fast growing rate, adaptability, resistance to diseases and higher meat quality compared to other exotic breeds (Casey and Van Niekerk, 1988; Barry and Godke, 1997). Boer goats are known to have a fast growing rate compared to other goat breeds. i.e. 180-280 g/day in first 12 months under good pasture conditions (Greyling, 1990). Male fertility is an important factor in caprine reproduction since numerous does are generally bred to a single buck. Hence, evaluation of male fertility prior to breeding is of paramount importance to achieve breeding success. Size and conformation are important characteristics in meat animals. Traditionally, animals are visually assessed, which is a subjective method of judgment. In goat’s body growth and development, objective means (linear body measurements) of describing and evaluating body size and conformation characteristics would overcome many of the problems associated with visual evaluation (Okpeku et al., 2011). Breeding soundness examination (BSE) is thus valuable and probably represents the most practical tool with which to select the potentially best breeding male animal in a flock, as demonstrated in beef bulls. Numerous studies have shown that testicular growth and development is closely related to body size. Other reports have investigated various phenotypic measurements.

Age is also one of the major contributing factors to differences in scrotal circumference and semen characteristics (Toe et al., 1994), with testicular size being closely related to total sperm output (Oldham et al., 1978; Ahmad and Noakes, 1995). For Boer bucks, information is almost non-existent with regard to the body conformation, testicular traits and BCS at different ages under semi-temperate conditions. So to avoid selection of infertile males there is a need of studies with regards to linear body measurement, testicular biometry and BCS at different age groups. The objective of this study was to evaluate linear body measurement parameters (body weight, stature, chest width, heart girth / chest girth, wither height, body depth, body length, flank width, rump width), BCS and testicular traits (scrotal circumference SC and testicular length and diameter) in Boer bucks at different age in local area.

Materials and Methods

Experimental Design and Animal Management

Seven Boer kids were purchased at the age of 4 – 5 months from Nimbkar Agriculture Research Institute (NARI), Phaltan, Maharashtra state and kept separately under routine management. Birth weight and weaning weight values were collected records from NARI. This study was conducted from 29^th to 49^th weeks of age at the Semen Collection Centre, Department of Veterinary Gynaecology and Obstetrics, Veterinary College, Bidar. Animals received routine inspection and dipping (ectoparasite), as well as anti-helminthic, drenching (deworming) and vaccination against endemic diseases. Drinking water was provided ad libitum. The experiment commenced when the bucks were 29^th week of age and terminated when they were 49^th week of age.

Data Collection and Traits Measurement

Body Weight Measurement

The body weight of the bucks was measured in kilograms by following the procedure as described by Akpa et al. (2013). Body weight was measured by digital weighing balance in kilograms.

Body Linear Measurement

Measurement of linear conformation traits were taken on the day of measurements in centimeters (cm) using flexible tape as described by Alphonsus et al. (2011) and Boisot et al. (2002). The measurements were taken at the onset and subsequently on weekly basis.

Heart Girth (HG): This is the circumference of the body at a point immediately behind the fore limbs and perpendicular to the body axis.

The Stature (ST): This was measured from the top of the spine in between the hips to the ground.

Chest Width (CW): This was measured from the inside the surface between the top of the front legs.

The Wither Height (WH): This is the highest point over the scapular vertically to the ground.

Body Depth (BD): This is the distance between the top of the spine and the bottom of the barrel at the last rib.

Body Length (BL): This was measured from the point of shoulder to the ischium.

Rump Width (RW): This is the distance between the most posterior points of pin bones.

Flank Width (FW): This is the highest distances between transverse process of lumbar vertebra.

Growth Rate (GR):  was calculated by using the formula.

Testicular Measurement

These were done at the onset and subsequently on weekly basis.

Testicular Length (TL)

This was measured in centimeter with a flexible measuring tape as the distance along the caudal surface of the scrotum, from its point of attachment to the tip of the scrotum as described by Akpa et al. (2013) and Bratte et al. (1999).

Scrotal Circumference (SC)

It was measured (cm) by encircling the neck of the scrotum with the hand using the finger to push the testicles ventrally to eliminate wrinkles in the scrotal skin. The scrotal tape was passed over the scrotum and tightened at the point of greatest circumference to note down the reading.

Scrotal Diameter (SD)

Was calculated in centimeters by standard formula i.e. measured scrotal circumference (SC) is product of one by pie (P) where P = 22/7 or 3.143.

SD=SC x 1/p

Body Condition Score

The body condition score of the Boer goats was assessed subjectively and ranged from a score of 1 to 5. Amount of fat deposit was determined by the use  of  fingertip  pressure  that  was  exerted  on  the  backbone,  pin  bone  and hipbone respectively Akpa et al. (2013).

Statistical Analysis

Statistical  analysis  such  as mean,  standard  error  and co-variance were recorded variables and compared  using the mixed  design ANOVA model tests for repeated measures, considering the treatments (in various parameters) and the age and their interaction as fixed effects and the animal into the random effect. Linear measurements of body measured in the standard statistical analysis. Data were presented as mean and mean standard error of the mean. Statistical  analyses  of  data  were  carried  out  as  per  ANOVA  method (Snedecor and Cochran, 1994).

Results and Discussion

The mean body weight, Body linear measurements, scrotal parameters and BCS from 29^th  to 38^th  week and 39^th  to 49^th  week is shown are Table 1 and Table 2 respectively. In the present study, it was revealed that the linear body measurement parameters viz. body weight, stature, chest width, heart girth/chest girth, wither height, body depth, body length, flank width, rump width, testicular length and body condition score were increased significantly (P<0.01) from 29^th to 49^th weeks of age (Table 1 and 2).

Table 1: Linear body and testicular measurements from birth to 38th weeks of age in Boer kids

The present study results are in accordance with the reports of Paul et al. (2011) and Akpa et al. (2013) who have stated that there is positive correlation between the increased body measurement values and their specific age periods in Black Bengal goats and Red Sokota goats respectively. Along with this, Akpa et al. (2013) also reported that bucks with higher BCS (4) produced more semen volume (SV) than those with lower BCS (3).

The results in the present study are in accordance with findings of Madani and Rahal (1988) and Bilaspuri and Singh (1992), who reported a rapid growth in kids above age of 180 days in Southern male kids and Local male goat kids and in 4–11 months of age in Malabari male goat kids respectively. Bhat (1988) observed that Jamunapari breed had variation in the body height from 58 to 98 cm for males and from 55 to 104 cm for females. The average body height in Sangamneri breed males value was 80.20 ± 2.22 cm while in females the value varies from 69.83 ± 0.66 cm in (Misra and Koratkar, 1994). Addition to this the similar results were observed by Bilaspuri and Singh (1992) in Surti and Marwari breeds of goat kids, which showed rapid growth post to 6 months. Body weight is often the most common and informative measure of animal performance. In the present study the body weight increased significantly (P < 0.01) from 29th week (16.53±1.23) to 49^th week (23.39±1.48). Similarly, Pathodiya et al. (2004) also reported that in Sirohi goats the body weights increased from three, six, nine and 12 months as 11.39, 16.49, 20.03 and 23.39 kg, respectively and the average daily gain in body weight at birth, 3months, 3-6 months, 6-9 months and 9-12 months was 88.64 ±2.27, 51.23 ± 2.99, 47.00 ± 3.17 and 41.77 ± 3.63 kg respectively. Madani and Rahul (1988) stated that Southern (S) kids and Libya (L) kids reached sexual maturity as significantly at very younger age and lighter weight (158.7 ± 6.7 days and 18.9 ± 0.9 kg) and (192.1 ± 7.0 days and 22.0±1.0 kg), respectively (P < 0.01).

In the present study the heart girth increased significantly (P < 0.01) from 29^th week to 49^th week and heart girth at 49^th week of age was 67.14±1.44. The results of heart girth are in consistent with reports of Matlova (1998) and Ambhore et al. (2003). Ambhore et al. (2003) reported that the Berari goats of Nagpur region had mean body length 45.77 ± 0.71 and 50.11 ± 0.62 cm, height at withers 54.00 ± 0.43 and 60.77 ± 0.55 cm respectively in females at 6 months and 9 months of age. The results are in consistent with the present study (Table 1 and 2) Whereas, Ali et al. (2004) reported the slightly lower mean values of body length (36.37 cm and 36.10 cm) and height at withers (53.16 cm and 53.41 cm) in males at 6 months and 9 months respectively. The probable reason for variation could be due to species, breed and climate variation. Attah et al. (2004) found no significant differences between males and females of goat kids at 10, 15 and 20 kg in measurements of chest girth; wither height and pelvis height in Red Sokoto goats.

Table 2: Linear body and testicular measurements from 39^th to 49^th week in Boer kids

*P-values (P <0.01) significant at 1%,  **P-values (P <0.05) significant  at 5%.

In the present study, the scrotal circumference (SC) and scrotal diameter (SD) were also increased significantly (P<0.05) from 29^th (16.64±1.62 and 5.30±0.51) to 49^th (23.14±1.22 and 7.36±0.39) weeks of age. According to Okere et al. (2014) found that SC is positively correlation with body conformation traits such as BW (0.61), CG (r = 0.53), HTW (r = 0.41) respectively. In addition, SC and BW increased (P<0.01) linearly from week 6 through 1 year and the results are in consistent with the present study. Based on the results, it can be interrelated that SC measurements, when used in conjunction with body weight can be valuable tool for breeding soundness assessment of Boer goat sires at an early age.

Conclusion

As there is a paucity of data on breeding soundness in Boer goats, the present study was conducted and as age advances linear body measurements, testicular measurements and body condition score of Boer kids increases significantly. The study showed positive relation of age with testicular measurement and linear body measurement and this would help in predicting the semen production ability as well as provide information that will be useful in early selection of sires for genetic improvement in Boer goats.

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