Gross morphological and sex wise morphometrical studies on the tenth, eleventh, twelfth and thirteenth thoracic vertebrae of Blue bull (Boselaphus tragocamelus)

The Blue bull (Boselaphus tragocamelus) is known to be one of the biggest antelopes in Asia and is widely found in both the forests and adjoining villages with enough green grass (Sathapathy et al., 2017). It belongs to the family Bovidae and comes under the genus Boselaphus (Sathapathy et al., 2018a). It is quite prevalent in northern and central parts of India especially in the foothills of Himalayas, eastern part of Pakistan and southern part of Nepal, but has vanished from Bangladesh (Sathapathy et al., 2018b). The adult male appears like ox and so called as Blue bull. They are usually seen in day times in the meadow pasture, timberland areas and agricultural land area. It prefers mostly plain or grassy plain and low hilly areas with shrubs, small bushes, scrub forests with scattered trees and does not usually found in dense forest areas, dense compact wood, etc. The Blue bulls are safeguarded beneath the IUCN since 2003 and also under safeguard of ‘Schedule III’ of the Indian Wildlife Protection Act, 1972 (Bagchi et al., 2004). The Blue bull is safeguarded in various parts of India such as Gir National Park (Gujarat), Kumbhalgarh Santuary (Rajasthan) and Panchamarahi Biosphere Reserve, India. The massive body of the Blue bull can be attributed to the large skeleton of the antelope. Further, the skeleton comprises of large and massive bones of axial and appendicular skeleton that not only protects the viscera, but also provides shape and support to the heavy musculature of the Blue bull (Sathapathy et al., 2018c and Sathapathy et al., 2018d). The present osteological study will furnish baseline data on the tenth, eleventh, twelfth and thirteenth thoracic vertebrae of adult Blue bull that would immensely help the wild life anatomists and Veterinarians in species identification and solving forensic and vetero-legal cases.

The present study was carried out on the tenth, eleventh, twelfth and thirteenth thoracic vertebrae of six specimens of adult Blue bulls (Boselaphus tragocamelus) of either sex. The permission for the collection of bones was acquired from the Principal Chief Conservator of Forests (PCCF),  Government of Rajasthan. The bones were possessed from the Jodhpur Zoo, Rajasthan getting authentic confirmation from the Principal Chief Conservator of Forests (PCCF), Government of Rajasthan. The skeletons were taken out from the burial ground that was located in the premises of the office of the Deputy Conservator of Forest Wildlife (WL), Jodhpur. The specimens were macerated and cleaned for further studies. The gross study was conducted under the supervision of the Zoo Authority, Jodhpur, India. The different biometrical parameters of tenth, eleventh, twelfth and thirteenth thoracic vertebrae of Blue bull were measured and subjected to routine statistical analysis as per standard technique given by Snedecor and Cochran (1994) and independent samples t-Test with Systat Software Inc, USA and SPSS 16.0 version software.

The thoracic vertebrae were thirteen in number in the Blue bull irrespective of sex (Fig 1). The present findings obeyed the observations made by Getty et al., (1930) in ox and sheep, Brelend (1943) in cat, Raghavan (1964) in ox, Miller et al., (1964), Kumar et al., (2000) in red deer, Dyce et al., (2006) in dog, Ozkan (2007) in mole-rats and Meena (2012) in chital. The tenth, eleventh, twelfth and thirteenth thoracic vertebrae were characterized by long supraspinous process, cylindrical, but short centrum (Fig 2 and Fig 3). The centrum was distinctly constricted in the middle. It presented a thin-edged ventral crest. The arch presented shallow notches and was perforated by intervertebral foramina at its caudal aspect. They also presented cranial and caudal facets on either side of their bodies. The transverse process was thick, strong and presented a rounded non-articular mammillary process and a facet ventrally that articulated with the facet of the tubercle of the corresponding rib. The mammillary processes were fused with the anterior articular processes in T₁₂ and T₁₃. The dorsal suprasinous process presented two surfaces, two borders and a summit. The lateral surfaces were found to be convex and the borders were nearly straight with thick margins. The backward slope of the dorsal supraspinous process decreased from T₁₀ to T₁₂. The supraspinous process of T₁₃ was vertical and wide like lumbar vertebra. The present finding was same as in ox and horse (Getty et al., 1930), in ox (Raghavan 1964), in dog (Miller et al., 1964), in camel (Smuts and Bezuidenhout, 1987), in mole-rats (Ozkan, 2007). However, the dorsal supraspinous processes of T₁-T₁₁ were caudally-sloped in porcupine (Yilmaz, 1998) and T₁-T₁₀ of otters (Yilmaz et al., 2000).
        
The costal facets were placed on either side at the end of the articular extremities of the centrum. However, the posterior costal facets were absent in T₁₃. Each articular facet was a demi-facet that articulated with the half the part of the head of the rib. The cranial vertebral notches were found to be shallower and smaller, but the caudal ones were deeper. The caudal arch was perforated by an additional intervertebral foramen on either side. The cranial articular processes were represented by oval facets on the anterior part of the arch and directed upwards except in T₁₁, where they are triangular in shape, whereas the caudal ones sprang from the base of the dorsal supraspinous process. Further, the left caudal artcular facets of T₁₃ was placed at a higher level than the right ones.
 
Biometrical observation
 
The biometrical observations on vertebrae revealed characteristic differences between the sexes of the Blue bull.
 
Tenth thoracic vertebra
 
The different biometrical parameters of tenth thoracic vertebra were represented in Table 1. The average width of the body at the middle was found to be 2.10±0.03 cm in adult Blue bull. Further, it was measured to be 2.05±0.03 cm and 2.14±0.03 cm in females and males respectively. Pandey et al., (2016) in tiger (Panthera tigris) reported that average widths of the body of T₁₀ at the anterior, middle and posterior aspects were 3.04±0.09 cm, 2.60±0.06 cm and 4.32±0.08 cm respectively.
 

 
Eleventh thoracic vertebra
 
The different biometrical parameters of eleventh thoracic vertebra were represented in Table 2. The average width of the body at the middle was found to be 2.82±0.02 cm in adult Blue bull. Further, it was measured to be 2.79±0.02 cm in females that was significantly lesser (P<0.05) than that of males, where it was found to be 2.85±0.01 cm. Pandey et al., (2016) in tiger (Panthera tigris) reported that the average widths of the body of T₁₁ at the anterior, middle and posterior aspects were 3.02±0.07 cm, 2.65±0.09 cm and 4.04±0.09 cm respectively.
 

 
Twelfth thoracic vertebra
 
The different biometrical parameters of twelfth thoracic vertebra were represented in Table 3. The average width of the body at the middle was found to be 2.80±0.02 cm in adult Blue bull. Further, it was measured to be 2.77±0.03 cm and 2.83±0.02 cm in females and males respectively. Pandey et al., (2016) in tiger (Panthera tigris) reported that the average widths of the body of T₁₂ at the anterior, middle and posterior aspects were 3.70±0.08 cm, 2.92±0.12 cm and 4.08±0.03 cm respectively. The average length of transverse process was found to be 1.85±0.01 cm in adult Blue bull. Further, it was measured to be 1.83±0.02 cm and 1.88±0.02 cm in females and males respectively. Kumar et al., (2000) found that the transverse process lengths (TPL) were fairly uniform in the thoracic spine in red deer. The minimum TPL was found to be 1.10 ± 0.082 cm at T₁₂. Meena et al., (2012) also stated in chital that the TPL minimum was 1.6 ± 0.06 cm at T₁₁ and T₁₂. Choudhary et al., (2015b) reported that the TPL maximum was found to be 1.96 ± 0.009 cm at fourth and fifth thoracic vertebra and TPL minimum was 0.96 ±0.01 cm at T₁₁ and T₁₂ vertebra in Black buck.
 

 
Thirteenth thoracic vertebra
 
The different biometrical parameters of thirteenth thoracic vertebra were represented in Table 4. The average width of the body at the middle was found to be 3.15±0.02 cm in adult Blue bull. Further, it was measured to be 3.12±0.02 cm in females that was significantly lesser (P<0.05) than that of males, where it was found to be 3.18±0.01 cm. Pandey et al., (2016) in tiger (Panthera tigris) reported that the average widths of the body of T₁₃ at the anterior, middle and posterior aspects were 3.78±0.06 cm, 2.80±0.02 cm and 4.00±0.06 cm respectively.
 

The tenth, eleventh, twelfth and thirteenth thoracic vertebrae of Blue bull were characterized by long supraspinous process, thick transverse processes, cranial and caudal articular facets and cylindrical, but short centrum. Further, the various biometrical parameters of the tenth, eleventh, twelfth and thirteenth thoracic vertebrae like average length, width and height of body, average width and height of dorsal supraspinous process, average length and width of cranial and caudal articular facets, average length of transverse process, average diameter of tubercular facet, average diameter of intervertebral foramen, average distance between cranial and caudal costal facets and articular facets, average transverse and vertical diameters of vertebral canal were significantly (P<0.05) more in males than female animals in the Blue bull. There is no previous information on these parameters in the tenth, eleventh, twelfth and thirteenth thoracic vertebrae neither of Blue bull, nor in any other domestic animals with which comparisons could be made. We therefore believe that the data presented above would form a baseline for further work especially comparability and compatibility are now desirable traits as efforts are geared up towards massive improvement in the livestock sector of the international economy.

The authors are grateful to the Dean, CVASc., GBPUA&T, Pantngar, Uttarakhand and Ministry of Environment of Forests (MoEF), New Delhi and Jodhpur Zoo, Rajasthan, India for providing facilities and support for carrying out research on the bones of Blue bull. Funding was provided by Department of Science and Technology, New Delhi and Indian Council of Agricultural research, New Delhi, India as Ph.D. grant (DST-INSPIRE Fellowship and ICAR-SRF (PGS)) to the first author.