Growth, carcass and behaviour characteristics of castrated and intact male grasscutters (Thryonomys swinderianus)

Forty eight (48) male and twelve (12) female grasscutters, 4-5 months old and weighing between 0.69-1.94kg were used for the study. The male grasscutters were divided into two (2) groups of 0.69-1.00kg and 1.18-1.94kg live weights, constituting two blocks (blocks 1 and 2). Twelve (12) male grasscutters from each block were randomly selected and surgically castrated. The Randomized Complete Block Design (RCBD) was used. To find the effect of castration on growth and carcass characteristics, two treatments, namely, intact males (IM) and castrates (CS) were used. Carcass evaluation was conducted using eight (8) intact males and eight (8) castrated grasscutters. To find the effect of castration on behaviour of grasscutters, castrated and/or intact grasscutters were mixed in the same cage with or without a female. The treatment groups were intact males only (IM), castrates only (CS), intact males and females (IMF), castrates and females (CSF), intact males and castrates (IMCS), and intact males, castrates and females (IMCSF).

Keywords: carcass composition, castration, docility, feed intake, organoleptic characteristics, rodent, weight gain

Introduction

Grasscutter is a wild rodent. Its meat is a delicacy and it is the most preferred and perhaps the most expensive meat in West Africa (Mensah and Okeyo 2006). The meat attracts higher prices than beef, mutton, chevon, chicken and pork (Olomu et al 2003). The high demand for grasscutter meat has led to its domestication in the West African sub-region. NRC (1991) observed that successful domestication of grasscutter could bring about a reduction in Africa’s chronic protein shortage.  

The immense benefits of grasscutter production have led to the widespread promotion of grasscutter farming by individuals, governmental and non-governmental organizations in the West African sub-region. The progress in the domestication process has however been slow due to paucity of information on the biology of the grasscutter (Yeboah and Adamu 1995).  

The grasscutter has nervous temperament and are difficult to rear in captivity (Hemmer 1993). On attainment of puberty, male grasscutters in colony fight a lot, most often resulting in injuries and deaths (Mensah et al 2005). Traumatic injuries caused 32% of mortalities in a colony of grasscutters (Adu 2002). Aggression and hostility, leading to high mortality, is of great concern in the grasscutter industry, as it lowers productivity. Aggressive behaviour further reduces feed intake and this could translate into slow growth rate. One solution to this problem is to separate males into individual cages at puberty. This would however require many individual cages. However, buying many cages may be too expensive for the poor farmer (Annor et al 2009). The high cost of cages limits separating sexually mature males into individual cages. In this regard, there arises the need to research into other husbandry practices to find solution to the problem. Castration is an option to be considered.  

The objective of this study was to find the effects of castration on growth, carcass and behaviour characteristics of sexually mature male grasscutters. 

Materials and Methods

Experimental Site and Period of study 

The study was conducted at the grasscutter section of the Department of Animal Science Education of the College of Agriculture Education, University of Education, Winneba, Asante Mampong, Ghana. The vegetation and climate of the study area have been described by Annor et al (2012). The study took place between April-August, 2009 in three phases. The first phase was carried out from April to July, 2009. The second and third phases took place in August, 2009. 

Experimental Animals 

Forty eight (48) male and twelve (12) female sexually mature grasscutters, 4-5 months old and weighing 0.69-1.94 kg were used for the experiment. The male grasscutters were divided into two (2) live-weight groups of 0.69-1.0 kg and 1.18-1.94 kg, respectively. Each group constituted a block. Twelve (12) male grasscutters were randomly selected from each block and castrated. 

Castration of Grasscutters 

The surgical method of Andersen (2007) with anesthesia (Mensah et al 2005) was used in castrating the grasscutters. The males were restrained by covering the head and thorax regions with cloth bag (Rand 2001), and handled by two persons. Lidocaine concentration of 4% (Rand 2001) was injected intra-muscularly into the scrotal and pelvic regions at a rate of 1ml/kg live-body weight, after disinfecting the area with methylated spirit. The testicles were located by palpating the inguinal area and incised with a scalpel blade. The spermatic cord with its associated testicular blood vessels were located and ligated to prevent internal bleeding. Oxytetracycline aerosol was sprayed onto the incised tissues to disinfect and facilitate quick wound healing. There was 100% wound healing at 2 weeks after castration in all the animals.

Management of Experimental Animals

Housing 

The grasscutters were housed in 3-tier wooden cages lined with wire mesh. In the first phase of the experiment (investigating the effect of castration on growth and carcass characteristics), the grasscutters were housed in individual cages with dimensions of 50cm x 50cm x 40cm. In the second phase (investigating the effect of castration on behaviour of grasscutters), each cage had a dimension of 100cm × 50cm × 40cm with a floor space of 94.92cm × 44.92cm, accommodating 2-3 animals. Each cage apartment was barricaded with iron roofing sheets to prevent grasscutters in one apartment from seeing and reaching others in adjacent apartments.

Health care 

Cages were disinfected with a disinfectant (Dettol solution) at a rate of 7.5ml/l of water before the start of the experiment. The cages, feeding and watering troughs were cleaned each day before feeding the animals. Grasscutters that sustained external injuries were treated with Oxytetracycline aerosol spray that contained 5mg of Oxytetracycline hydrochloride.

Feeding and watering   

The grasscutters were fed ad libitum with elephant grass (Pennisetum purpureum) as the basal diet and supplemented with concentrate, containing 14% crude protein, and fed at a rate of 50g per animal per day. Proximate analysis of the concentrate diet and that of elephant grass were carried out in the laboratory.  The composition of the concentrate diet and the results of the proximate analysis are shown in Tables 1 and 2, respectively. The concentrate was moistened with water at a rate of 6.12ml/50g (0.1224ml/g) to reduce dustiness and avoid choking of the animals. The grasscutters were fed and provided with fresh drinking water ad libitum daily.

Data Collection 

Feed intake and live weight 

Grass, concentrate and left-over feed were weighed with electronic weigh master digital scale (Penn Scale Manufacturing Company, Philadelphia).  Daily feed intake was computed by calculating the difference between the amount of grass and concentrate fed and the left-over feed. The live grasscutters were weighed with electronic weigh master digital scale fortnightly and their weights recorded. Feed conversion ratio (FCR) was computed as ratio of feed eaten to gain in weight.     

Injuries and mortalities 

All injuries and deaths were recorded as and when they occurred. Post-mortem examination was conducted on each dead animal.  

Docility 

Docility was defined as the ability of an animal to accept human presence (Annor et al 2011). The capacity of an animal to accept human presence was scored on a scale of 1 to 4 (Mensah and Okeyo 2006; Annor et al 2011). The scores were as follows: 

• Score 1: Docile – animal is friendly and accepts being touched and caressed;

• Score 2: Flighty – animal accepts to be touched but moves away without panic;

• Score 3: Restless – the animal does not allow physical human contact. It stays away and moves around in the cage. It is excited and agitated; and

• Score 4: Indocile – the animal jumps when it sees somebody in an attempt to escape. It hits itself on the sides of the cage. It is in complete panic.

Carcass evaluation 

Sixteen (16) grasscutters comprising 8 intact males and 8 castrates were randomly selected and slaughtered for carcass evaluation at the end of the experiment. Carcass weights were recorded using an electronic weigh master digital scale. After scalding with hot water at a temperature of 80^oC (Omole et al 2005), the carcasses were weighed again using an electronic weigh master digital scale to obtain the defurred weights. The carcasses were dissected with a sharp knife and the internal organs were removed. Whole and individual viscera (heart, liver, kidneys, lungs and spleen) and fat from the visceral organs were weighed on an electronic weigh master digital scale and their weights recorded. The weights of the eviscerated carcasses, hot and cold, were also recorded and the dressing percentages calculated using the formula: (Dressed carcass weight/Slaughter weight) x 100 

Chemical composition of grasscutter meat 

Castrate and intact grasscutter meat samples were taken for chemical analysis. Two meat samples of 100 g each were taken from each treatment. Each sample comprised 100 g meat from the longissimus dorsi muscles, loins, fore legs, hind legs, thorax, neck and abdomen, respectively. The meat samples were put in plain polythene sheets separately and frozen for 24 hours in a deep freezer. The frozen samples were transported in cold flask containers to the laboratory. Samples were kept frozen in a deep freezer and analyzed 48 hours after slaughter. Moisture, energy, protein, lipid, pH and ash contents of meat were determined according to the procedure of AOAC (1980).

Organoleptic/sensory evaluation of grasscutter meat

Sensory evaluation was conducted on the meat of intact and castrated grasscutters, as described by Van Heerden et al (2007) and Osman and Aldosari (2006). Sensory panelists were given 4 hour training on sensory evaluation procedures at the Science Laboratory of the University of Education, Winneba, Asante Mampong. Ten (10) trained sensory panelists took part in the sensory analysis. Meat was taken from the animals’ fore legs, hind legs, Longissimus dorsi and skin.  

The meat samples were frozen in a deep freezer for 36 hours and cut into 1.5cm³ sizes, each weighing about 8g. Ten meat cubes from each part were cooked separately for 10munites in 65ml of water with 3g of salt. 

The meat cubes were served warm to 10 trained panelists in panel booths. Five minutes break was allowed between each of the 8 sessions for mouth rinsing to reduce sensory fatigue and halo effects. The meat cubes were coded and served randomly to ensure that each panelist evaluated every sample at the end of the test.  

Each panel member tasted 8 different samples of meat from intact and castrated animals.  The panelists evaluated meat colour, meat colour intensity, aroma, juiciness, texture, flavour and over all acceptability (Omole et al 2005) using a score sheet with 7 point hedonic scale (Osman and Aldosari, 2006). Panelists used colour charts and designed meat attribute description chartsin rating the meat (Van Heerden et al 2007). A meat coding chart was used to conduct the sensory evaluation.

Experimental Design and Treatments 

The experiment was conducted using the Randomized Complete Block Design (RCBD). The live-weight groups, 0.69kg-1.0kg and 1.18kg-1.94kg of grasscutters constituted blocks 1 and 2 respectively.  The experiment was conducted in three (3) phases. In the first phase, there were 2 treatments (intact males and castrates) using RCBD. Each treatment was replicated 6 times in a block. This phase lasted for 8 weeks and sought to determine the effect of castration on growth and carcass characteristics of grasscutters.  

In the second phase, there were 6 treatments and 4 replications. The experimental treatments were made up of colonies of intact males, castrates or intact males and castrates, with or without females as follows:  

To further enhance easy identification, the experimental animals were fitted with ear tags of varying colours. Intact males, castrates and females were fitted with red, white and black coloured tags respectively. This phase lasted for 8 weeks and sought to determine the effect of castration on docility and aggressive behaviour of grasscutters. Injuries and mortalities were recorded at this phase.  

In the third phase there were three sub-phases. Sub-phase 1 was to evaluate carcass characteristics. That is, slaughter weight, dressed carcass weight (hot and cold), dressing percentages (hot and cold), organ weight and viscera fat weight of grasscutters. There were 2 treatments (intact males and castrates) with 8 replications. Sub-phase 2 was to determine the chemical constituents of grasscutter meat. There were 2 treatments (intact males and castrates), each with 12 replications. Sub-phase 3 was to conduct the sensory analysis of intact and castrated grasscutter meat. There were 2 treatments (intact males and castrates) with 10 replications. 

Data analysis

Data were analyzed using Analysis of Variance (ANOVA) and General Linear Model (GLM) procedures of Statistical Analysis System (SAS 2008). Data on docility were analyzed using Generalized Linear Mixed Models (GLMM) with GLIMMIX procedure of SAS (SAS 2008). Differences between means of significant effects were separated by the Probability of Difference (PDIFF) procedures of the Statistical Analysis System (SAS 2008). 

Results and discussion

Feed utilization and growth performance of grasscuters 

There were no differences between intact males and castrates for initial and final live weights, and total weight and daily weight gains (Table 3). However, daily dry matter intake was lower in castrates than in intact males which translated into a better feed conversion ratio by castrates. 

Mensah et al (2005) reported similar results to this study in feed conversion ratio. However, in that same study, castrates performed better than intact males in terms of live body weight and daily weight gain. Grasscutters castrated between 1-2 months of age grew 1.4 times faster than intact ones of the similar age (Mensah et al 2005). However, Alogninouwa et al (1999) reported that growth rate of male grasscutters castrated over four months of age was found to be lower than that of intact males. There have been contradictory reports in other species. In cattle, castration reduced feed intake (AVMA 2007) but in goats it improved it (Muhikambele et al 1994). Studies on the effect of castration on the growth rate of rams have also shown contradictory findings (Bani-Ismail et al 2007).  

Injuries 

Animals in colonies of intact males only (IM), castrates only (CS), intact males and females (IMF) and castrates and females (CSF) sustained body injuries (Table 4). Similar numbers of injuries were observed in intact males only (IM), castrates only (CS) and castrates and females (CSF) on one hand, and intact males (IM), intact males and females (IMF) and castrates and females (CSF) on another hand (P> 0.05). The castrates only (CS) sustained higher number of injuries than the intact males and females group (IMF). Injuries found on the animals were located around their snouts, loins, fore quarters and hind quarters. No injuries were recorded in colonies of intact males and castrates (IMCS) and intact males, castrates and females (IMCSF). 

Castration of grasscutters between ages 4-5 months could not eliminate injuries caused by the aggressive behaviour of the animals because both castrates and intact males were injured to the same degree. The result is in agreement with report by Manharth and Harris-Gerber (2002) that significant aggressive fighting and injuries were observed in colonies of castrated Rock hyrax (Procavia capensis). The result is however contrary to report that castration of male rats decreased aggression significantly (DeBold and Miczek 1981). The injuries in this study were observed to have been caused by aggressive behaviours, particularly fighting. The animals fought by using their claws and teeth to scratch and bite respectively, thereby resulting in external injuries. No aggressive fighting was observed in the colonies of intact males and castrates (IMCS) and intact males, castrates and females (IMCSF), and hence no injuries were sustained by animals in these treatments. Therefore, intact males and castrates mixed in colony, with or without females (IMCS and IMCSF) co-existed peacefully than other treatments. As to why such phenomenon happened is still not well understood and requires further investigations. 

Mortalities

The proportion of animals that died in all treatment groups was similar, with the exception that higher proportion of animals was lost in the intact males and females groups (IMF) than the intact males only group (IM) (Table 4). This observation is in agreement with reports presented by Mensah and Okeyo (2005) and Adu (2002) that male grasscutters at puberty can fight to death in the presence of females. Djang-Fordjour et al (2012) also noted that when males are reared together from puberty they become constantly aggressive and hostile towards each other. From the post mortem findings, internal bleeding as a result of fighting was one major cause of deaths in all treatments. Septicaemia was responsible for the deaths recorded in colonies of intact males and castrates (IMCS) and intact males, castrates and females (IMCSF). Septicaemia has been observed to cause about 13.6% (Djang-Fordjour et al 2012) and 12.0% (Jori and Cooper 2001) of deaths in grasscutters, as a result of injuries. 

Docility  

Animals in all the treatments had similar docility scores (Table 4). The current finding contrast previous reports that castration promotes docility in cattle (Turk 2007; Stafford and Mellor 2005). Based on the results, it could be determined that castration alone was not enough to ensure success in significantly reducing inter-male aggressive behaviours of grasscutters in colony. Other factors such as live weight and growth rate also influence docility. For example, it has been reported that cattle with higher body weight are more docile than those with lower body weights, and grew faster during fattening than aggressive animals (Fordyce et al 1988). These other factors need to be investigated in combination with docility to find their combined effect on aggressive behaviour of grasscutters.

Carcass weight, organ weight and dressing percentage of grasscutters  

Castration had little influence on carcass weight (hot/cold), dressing percentages (hot/cold), internal offals (plus or less fat), and heart, liver, kidneys, lungs and spleen proportions (Tables 5). 

Similar findings were reported in Awassi lambs (Haddad et al 2006). The result may be due to the late castration as delayed castration was reported to confer no benefits in terms of carcass weight (Fisher et al 2001). Castration did not influence eviscerated weight and dressing percentage at 32 weeks of age of Pheasants (Severin et al 2007). Fat content, which is often a great concern as a public health issue was also not significantly affected by castration (Table 5). In goats, it was observed that early castration is recommended for thick fat deposition in the meat (Kebede et al 2008). Other reports also show that early castration of Damascus goats produced fatter carcasses in castrates than in intact males (Louca et al 1977).

Chemical composition  

The chemical composition of the meat of intact males and castrates were similar with regards to moisture content, energy, protein, fat, pH and ash (Table 6). However in other studies, castration had effect on fat and moisture content of meat. In pheasants, fat and moisture in the meat were reported to be higher in castrates than in intact males and protein content was also lower in castrates than intact males (Severin et al 2007). Higher intramuscular fat deposition was reported in castrated goats than in intact males (Koyuncu et al 2007). In cattle, higher protein content with lower moisture contents were observed in castrates than in intact males (Destefanis et al 2003).  

Organoleptic/sensory characteristics  

Among all variables evaluated on sensory characteristics of meat, panelists were able to determine differences between only longissimus dorsi muscle colour intensity of intact males and castrates (Table 7). Castrates produced lighter longissimus dorsi muscle colour than intact males. Castration had little influence on cooked meat colour. The meat colour for both intact male and castrates ranged from ivory to yellow lemon for fore legs, and ivory to light ivory for hind legs, longissimus dorsi muscle and skin. The cooked meat aroma, juiciness, texture and flavour were also slightly influenced by castration. Similar reports were presented by Morgan et al (1993) in cattle.  

Generally, the meat of intact males and castrates were both acceptable as sensory panelists could not detect any differences in both (Table 7). Significant differences did not occur between cooked meat attributes of intact males and castrates perhaps because of the late castration of the animals. Late castration confers no benefits in terms of taste/flavour (Shahidi 1994) and fat deposition (Kebede et al 2008).

Conclusion

• Castration of grasscutters between 4-5 months of age had little influence on body weight and growth rate. Castration however influenced grasscutters to consume and utilize feed better than intact males.

• Injuries occurred in both intact males grouped alone and castrates also grouped alone as a result of fighting. However, castrates and intact males grouped together co-existed peacefully.

• Mortality was higher in intact males and females group than in intact males only group.

• Docility could not be achieved by castration of grasscutters between 4-5 months of age.

• Castration had little influence on carcass weight (hot/cold), dressing percentages (hot/cold), internal offals (plus or less fat), and heart, liver, kidneys, lungs and spleen proportions.

• Late castration had little influence on moisture, protein, fat, energy, pH and ash contents of grasscutter meat.

• Sensory panelists identified cooked grasscutter meat colours to range from ivory to yellow lemon for fore legs, and ivory to light ivory for hind legs and longissimus dorsi.

Recommendations

• For efficient feed utilization, male grasscutters should be castrated between ages 4-5 months.

• The work should be repeated by using castration at an early age at 2 months.

• For low fat content in meat, grasscutters should be castrated between ages 4-5 months.

References

Adu, E. K. 2002. Experiences of a Research Institute on Grasscutter Farming in Ghana. Deuxième Conférence sur la promotion de la diffusion de l’élevage d’aulacodes en Afrique au sud du Sahara, des 17,18 et 19 Decembre, 2002, Institut International d’Agronomie Tropicale (IITA), Godomey, (BENIN), pp. 1-17. 

Alogninouwa, T., Kpodekon, M. and Yewadan, L. T. 1999. Effects of castration on growth and endocrine pattern in the Grasscutter (Thryonomys swinderianus, Temminck, 1827). Annales de Zootechnie 48(3): 225-230 

American Veterinary Medical Association (AVMA) 2007. Backgrounder: Welfare implications of castration of cattle. Retrieved March 21, 2009, from http://www.avma.org/backgrounders/castration-cattle-bgnd-asp. 

Anderson, N. 2007. Castration of calves. Retrieved March 10, 2009, fromhttp://www.omafra.gov.on.ca/english/livestock/beef/facts/07-029.htm.  

Annor S Y, Adu E K, Donkor J, Otsyina H and Ahiaba J 2009. In: Grasscutter Production: A Handbook. Qualitype Ltd. Accra, Ghana, 109 pp.  

Annor S Y, Ahunu B K, Aboagye G S, Boa-Amponsem K, Djang-Fordjour K T and Cassady J P 2011. The genetics of docility of the grasscutter (Thryonomys swinderianus). Livestock Research for Rural Development, Volume 23, Article #176. Retrieved September 16, 2011, from http://www.lrrd.org/lrrd23/8/anno23176.htm. 

Annor S Y, Ahunu B K, Aboagye G S, Boa-Amponsem K and Cassady J P 2012. Non-genetic factors affecting grasscutter production traits. 1. Growth traits. World Applied Sciences Journal, 18(1): 1412-1424. 

Association of Official Analytical Chemist (AOAC) 1980. Official Methods of Analysis. Association of Official Analytical Chemists, Washington D. C.

Bani-Ismail Z A, AL-Zghoul M F, Al-Majali A M and Khraim N M 2007. Effects of castration on penile and urethral development in Awassi lambs. Bulgarian Journal of Veterinary Medicine 10(1): 29-34. 

DeBold J F and Miczek K A 1981. Sexual dimorphism in the hormonal control of aggressive behaviour in rats. Pharmacology of Biochemistry and Behaviour 14(1): 89-93. 

Destefanis G, Brugiapaglia A, Barge M T and Lazzaroni C 2003. Effect of Castration on Meat quality in Piemontese Cattle. Meat Science 64(2): 215-218. 

Djang-Fordjour H, Annor S Y, Djang-Fordjour K T and Antwi E. 2012. Profiling mortality in grasscutter (Thryonomys swinderianus) at the Department of Animal Science farm of the University of Education, Winneba. Proceedings of the 30^th Ghana Animal Science Association Conference 2010, Animal Research Institute, Frafraha, Accra, pp. 142-148.

Fisher, A D, Knight T W and Cosgrove G P 2001. Effects of surgical or band castration on stress responses and behaviour of bulls. Australian Veterinary Journal 79: 279-284.  

Fordyce G, Dodt R M and Wythes J R 1988. Cattle temperament in extensive beef herds in Northern Greensland. Factors affecting temperament. Australian Journal of Experimental Agriculture 28: 683-687. 

Haddad S G, Husein M Q and Sweidan R W 2006. Effects of castration on growth performance of Awassi lambs fed high concentrate diets. Small Ruminant Research 65(1-2):149-153. 

Hemmer, H. (1993). Domestication: Concept and consequences. In: Schrage, R. and Yewadan, L. T. (eds.). 1^ere Conference Internationale sur l’aulacodiculture: Acquis et Perspectives, pp. 189-202. 

Jori F and Cooper J E 2001. Postmortem findings in captive Cane Rats (Thryonomys swinderianus) in Gabon. The Veterinary Record 148(20): 624-628. 

Kebede T, Lemma T, Dinka H, Guru M and Sisay A 2008. Growth performance and carcass characteristics of Arsi-Bale goats castrated at different ages. Journal of Cell and Animal Biology 2(11): 187-194. 

Koyuncu M, Duru S, Kara Uzun S, Ozis S and Tuncel E 2007. Effect of castration on carcass traits in hair goat kids under a semi-intensive system in South Marmara Region of Turkey. Small Ruminant Research 72(1): 38-44. 

Louca A, Economides S and Hancook J 1977. Effects of castration on growth rate, feed conversion efficiency and carcass quality in Damascus Goats. Animal Production 24:387-391. 

Manharth A and Harris-Gerber L 2002. Surgical castration and the effect on aggression on Rock Hyrax (Procavia capensis). Journal of Zoo and Wildlife Medicine 33(1): 80-82. 

Mensah G A and Okeyo A M 2006. Continuous harvest of the diverse African Animal Genetic Resources from the wild through domestication as a strategy for sustainable use: A case of the larger Grasscutter (Thryonomys swinderianus). Retrieved March 15, 2009, from http://agtr.ilri.cgiar.org/agtrweb.  

Mensah G A, Huinato M, Koudande O D, Bembide C, Dossou-Gbete G S O, Mensah S E, Pomalegni C B and Et Kpera G N 2005. Castration of male grasscutter (Thryonomys swinderianus). Proceedings of the International Forum on Grasscutter: Promoting Grasscutter as a Business in West Africa, 12-16 Dec., 2005, Institute of Local Government Studies, Accra, Ghana. 

Morgan J B, Wheeler T L, Koohmaraie M, Savell J W and Crouse J D 1993. Meat tenderness and the Calpain Proteolytic System of longissimus dorsi muscle of castrated young bulls and steers. Journal of Animal Science 71(6): 1471-1476. 

Muhikambele V R M, Mtenga R A, Owen E, Kifaro G C, Sendalo D S C, Masawe N F, Kiango S M and Nkungu D R 1994. Effect of castration and diet on performance and feed utilization in Saanen goats. Proceedings of the 3^rd Biennial Conference of the African Small Ruminant Research Network, 5-9 Dec., 1994, UICC, Kampala, Uganda, pp. 1-7. 

National Research Council (NRC) 1991. Micro-livestock: Little-known small animals with a promising economic future. Washington D.C., National Academic Press. 

Olomu J M, Ezieshi V E and Orhueata A M 2003. Grasscutter production in Nigeria: Principles and Practice. A Jachem Publication, Nigeria 61pp. 

Omole A J, Ayodeji I O, Ashaye O A and Tiamiyu A K 2005. Effect of scalding and flaming methods of processing on the physico-chemical and organoleptic properties of Grasscutter meat. Journal of Applied Sciences Research 1(2): 249-252. 

Osman B M and Aldosari M N 2006. Sensory evaluation of Awassi and Najdi lambs’ meat. Scientific Journal of King Faisal University (Basic and Applied Sciences) 7(2): 137-146. 

Rand M S 2001. Handling, restraint and techniques of laboratory rodents. Retrieved March 21, 2009, from http://www.ahsc.arizona.edu/uac.  

Severin K, Masek T, Horvatek D, Konjevic D, Janicki Z, Cvrtila Z, Kozacinski, L, Mirza H and Baric-Rafaj R 2007. The effects of castration on the growth parameters, carcass yield and meat chemical composition of intensively reared common Pheasants (Phasianus colchicus colchicus). Italian Journal of Animal Science 6(2): 12-29. 

Shahidi F 1994. Flavour of meat and meat products: an over view. In:  F, Shahidi (ed). Flavour of meat and meat products. London: Blackie Academic and Professional pp. 1-3. 

Stafford K J and Mellor D J 2005. The welfare significance of the castration of cattle: A review. New Zealand Veterinary Journal 53: 271-278. 

Statistical Analysis System (SAS) (2008). SAS User’s Guide: Statistics. Statistical Analysis Institute, INC., Cary, North Carolina, USA. 

Turk D S 2007. Castration: Detailed discussion of cattle laws. Retrieved February 2, 2009, from http://www.animallaw.info/articles/ddusbovine.htm.

Van Heerden S M, Strydom P E, Schonfeldt H C, Kruger R and Smith M F 2007. Effect of fatness on meat quality of the loin cut of Sa Dorper lamb. Journal of Sensory Studies, pp: 237. 

Yeboah S and Adams E K 1995. The Cane Rat. Biologist 42: 86-87.

Received 24 November 2012; Accepted 16 February 2013; Published 1 March 2013

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