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X-Chromatin Status of Rabbits in Selected Farms in Port Harcourt, Nigeria.

Byline: V.N. NYECHE, O.J. OWEN AND L. NDOR - E-mail: congomfx@yahoo.com

ABSTRACT

A study was carried out to determine the X-chromatin status of rabbits in Port Harcourt-Nigeria. Sixty sexually and clinically healthy adult rabbits (30 males and 30 females) with their ages ranging from 8 to 9 months were used. Blood samples were collected on EDTA reinforced sample bottles via the ear veins and blood smears made on clean glass slides. Thereafter they were stained with Leishman's, rinsed in distilled water and air dried. With the aid of microscope, 200 polymorphonuclear neutrophils were examined for the presence of drumstick appendages. The results revealed that the females had an average X-chromatin status of 2.78%, while the males showed 0%. These values were within the normal range of 2-12% for females and 0.00%-2.00% for males. It was concluded that these animals may well be free from X-chromatin-related physiogenetic problems or malfunctions. (c) 2010 Friends Science Publishers

Key Words: Drumstick; Polymorphonuclear neutrophils; Rabbits; X-chromatin

INTRODUCTION

Reproductive abnormalities in livestock create serious health problems to Veterinarians and animal breeders. It is a major source of economic setback to farmers (Wekhe and Yahaya, 1999). They are not easy to manage because their causative factors are diverse, varied and complicated. Amongst the diverse causative agents of reproductive abnormalities, congenital or hereditary ones are most common (Galloway and Norman, 1976). Other factors involved include infectious agents, nutritional and environmental (Ruder et al., 1981) and chromosomal (Galloway et al., 1992). These abnormalities lead to sub-fertility or total infertility and sometimes to abortion, stillbirth or neonatal deaths, repeat breeding, anoestrus, congenital defects, poor libido, poor semen quality as well as stunted growth and general poor performance in young animals (Berepubo et al., 1993; Omeje et al., 1994; Wekhe, 1998).

The problem of inevitable prenatal loss has been ascribed to chromosomal aberrations observed by direct karyotyping of embryos from infertile or sub-fertile dams or sires (Long and Williams, 1980; Hare et al., 1980; Berepubo and Long, 1983; King and Linares, 1983; Berepubo, 1985; Murray et al., 1985). One of the several techniques for the diagnosis of such reproductive anomalies is X-chromatin (drumstick) evaluation. A number of such studies in domestic species have revealed the presence of some chromosomal anomalies in the affected animals (Bhatia and Shanker, 1982; Parkanyi et al., 2008).

The use of X-chromatin (drumstick) in diagnosing major X-related reproductive abnormalities and stunted growth in the animal industry has contributed greatly in the detection of reproductive anomalies and stunted growth (Bhatia and Shanker, 1984; Berepubo et al., 1993). The technique can thus be used in culling individuals exhibiting morphological abnormalities of X-chromatin appendages early in life so as to reduce the cost of production (Omeje et al., 1994; Berepubo and Umanah, 1996). In modern genetic parlance, X-chromatin evaluation refers to the analysis of X-chromosome only without reference to the Y-chromosome. The X-chromosome has been successfully used in domestic animals to predict the cytogenetic or genetic merit of various economically important species. These include early detection of potential sex chromosomal and developmental anomalies, which considerably impair fertility and also the prediction of the growth potential of neonates (Wekhe, 1998).

A normal fertile female animal cells are expected to show at least one X-chromatin appendage (Drumstick or Barr body) in a preponderant proportion i.e., in at least 90% of its cells (Bhatia and Shanker, 1983). X-chromatin is found in the nucleus of the somatic cells of a normal female as "Barr body "and in the leucocytes as 'Drumstick". The drumsticks occur in the nuclei of polymorphonuclear neutrophils (Davidson and Smith, 1954).

The assessment of the sex chromatin in animals is based on the premise that it represents the sexual status (XX and XY) chromosomes of a particular animal. Thus an animal could have abnormal sex chromosomes. On the contrary, To cite this paper: Nyeche, V.N., O.J. Owen and L. Ndor, 2010. X-Chromatin status of rabbits in selected farms in port Harcourt, Nigeria. Int. J. Agric. Biol., 12: 781-784 the males having XY complement have no Barr body or drumstick; but have "Y body". Thus a male that shows Barr body or drumstick is considered abnormal (Berepubo, 1989; Wekhe, 1998) just as a female that does not show these nuclear projections at all would also be suspended chromosomal anomaly (Berepubo and Umanah, 1996). The technique of X-chromatin (drumstick) evaluation has been used extensively in the selection of reproductive anomalies, which result in stunted growth in the animal industry (Bhatia and Shanker, 1984; Berepubo et al., 1993).

The main objective of this study is to determine the percentage incidence of x-chromatin appendage in male and female rabbits in selected farms in Port Harcourt, Nigeria.

MATERIALS AND METHODS

Feeding and management of experimental animals: The study was carried out at the rabbitry section of Rivers State Ministry of Agriculture farm, Rumuodomaya in Obio/Akpor Local Government Area. A total of 60 sexually and clinically healthy adult rabbits (30 males and 30 females) with their ages ranging from 8 to 9 months were used. The rabbits were procured from Ministry of Agriculture Rabbitry Farm Rumuodomaya (10 males, 10 females), Beulah Farms (10 males, 10 females) and De John's Farms, Oyigbo (10 males, 10 females). These animals were raised under intensive system of husbandry in metal hutches. The animals were housed individually in standard type, two tier metal hutches of four compartments each. The males were housed separately from the females to avoid mix up and indiscriminate mating. The rabbits were allowed two weeks pre-conditioning period. They were medicated against diseases such as mange and scabies.

Standard sanitary conditions such as daily washing of the feeders and drinkers, cleaning of the hutches and the floor were maintained. The rabbits were fed poultry growers mash and forages such as Panicum maximum (grass), Centrosema mubescens and Calopogonium nucunoides (legumes) ad libitum. The hutches were placed in a building with concrete floor designed to allow cross ventilation (half wall) and the rest with wire mesh.

Collection of blood samples: Blood samples of one ml each were collected from all experimental rabbits. Sterile syringes and hypodermic needles were used to aspirate blood from the ear veins of the animals. One sterile syringe and hypodermic needle was used per rabbit after cleaning the ears with cotton wool soaked with pure methylated spirit to avoid mixing and or contamination of the blood samples. After collection, the blood was immediately decanted into a sterile heparinized sample bottle to avoid coagulation and was taken to the laboratory for evaluation.

Staining and examination: A drop of the whole blood was dropped onto a clean glass slide using a Pasteur pipette and a smear was made. Two slides were made from each sample and allowed to dry. The slides were stained with Leishman's stain inundated with distilled water and air dried.

The slides were examined under the microscope at a magnification of x 100 objective. The polymorpho-nuclear neutrophils were examined for "drumstick" occurrence on the basis of 200 polymorphonuclear neutrophils screened/examined morphologically. Data analyses were obtained using simple percentage (%).

RESULTS AND DISCUSSION

The analysis of X-chromatin incidence is presented in Table I and II. The average percentage of drumstick incidence in the female rabbits evaluated was 2.78%, whilst for the males was 0.00%. The range of drumstick frequencies observed in this study per 200 poly-morphonuclear ncutrophils among the females screened was between 0-5%. These observations agree with the results observed by earlier workers (Bhatia and Shanker, 1984; Berepubo, 1994; Omeje et al., 1994; Wekhe, 1998). They observed X-chromatin (drumstick) frequency in normal bovine females to be 2.59-3.60% of PMNS. Also, Basrur (1984) reported that normal mammalian female has X-chromatin incidence of 2-12%. Omeje et al. (1994) also confirmed this in West African Dwarf (WAD) goats by observing a frequency of drumstick of 2.83% in normal females.

In the present study, the incidence of X-chromatin status of females was 2.78% suggesting that the females screened for X-chromatin were free of inherent X-chromosome-related reproductive anomalies since the X-chromatin status here lies within the normal range (2-12%) according to Basrur (1984). The presence of drumsticks or Barr bodies is an indication of inactivated X-chromosome (Berepubo et al., 2001) and this is consistent with femaleness or the presence of two X-chromosomes.

Similarly, the result of the X-chromatin evaluation of thirty (30) males was 0.0% per 200 PMNs. This range agrees with the work by Basrur (1984) who confirmed that normal mammalian males have X-chromatin incidence of 0.0%-2.0%. From this result, it could be deduced that these males were free from sex-chromosome-related reproductive problems.

Although the size of the drumsticks was not morphologically evaluated in this study due to non-availability of facilities, Berepubo (1985) observed a relationship between the size of drumsticks and the presence of structural abnormalities of X-chromosomes in humans as well as in farm animals. Observation of three (3) of the females that had zero% drumstick incidence may therefore suggest that they may not have been affected by any form of health or management problems; nevertheless the zero X-chromatin (drumstick) incidence of (3) three of the females may be suggestive of a fundamental genetic (sex-chromosomal) disorder with the consequence of reproductive failure (Long and Williams, 1980; Hare et al., 1980).

Table I: X-Chromatin status of female rabbits

Ident-

ifica-###No of

tion###cells

of###counted###No of drumsticks % incidence of

animal

(rabbit) (pmns)###observed###drumsticks

Fl###200###5###2.5

F2###200###4###2.0

F3###200###7###3.5

F4###200###5###2.5

F5###200###8###4.0

F6###200###9###4.5

F7###200###4###2.0

F8###200###0###0.0

F9###200###6###3.0

F10###200###8###4.0

Fll###200###5###2.5

F12###200###10###5.0

F13###200###6###3.0

F14###200###3###1.5

F15###200###8###4.0

F16###200###0###0,0

F17###200###7###3.5

F18###200###9###4.5

F19###200###5###2.5

F20###200###6###3.0

F21###200###5###2.5

F22###200###7###3.5

F23###200###4###2.0

F24###200###6###3.0

F25###200###4###2.0

F26###200###5###2.5

F27###200###0###0.0

F28###200###7###3.5

F29###200###8###4.0

F30###200###6###3.0

Mean###2.78

Table II: X-chromatin status of male rabbits

Ident-

ifica-###No of

tion###cells

of###counted###No of drumsticks % incidence of

animal

(rabbit) (pmns)###observed drumsticksMl###

M1###200###0###0

M2###200###0###0

M3###200###0###0

M4###200###0###0

M5###200###0###0

M6###200###0###0

M7###200###0###0

M8###200###0###0

M9###200###0###0

M10###200###0###0

Mil###200###0###0

M12###200###0###0

Ml 3###200###0###0

M14###200###0###0

M15###200###0###0

M16###200###0###0

M17###200###0###0

Ml 8###200###0###0

M19###200###0###0

M20###200###0###0

M21###200###0###0

M22###200###0###0

M23###200###0###0

M24###200###0###0

M25###200###0###0

M26###200###0###0

M27###200###0###0

M28###200###0###0

M29###200###0###0

M30###200###0###0

Mean###0.00

CONCLUSION

Based on the observations of this research and similar reports, X-chromosome markers can successfully be used in rabbits to predict the cytogenetic or genetic merits of various economically important species. Thus, from this research, the rabbits can be passed as having X-chromatin status unless otherwise affected by other factors.

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V.N. NYECHE, O.J. OWEN1 AND L. NDOR

Department of Animal Science, Rivers State University of Science and Technology, P.M.B 5080, Port Harcourt-Nigeria

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Publication:International Journal of Agriculture and Biology
Article Type:Report
Geographic Code:6NIGR
Date:Sep 30, 2010
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