Infl uence of Slaughtering Ages on Carcass Characteristics, Meat Composition and Haematology of Extensively Managed Red Sokoto Bucks Slaughtered In Abeokuta Metropolis, Nigeria

The study was conducted to evaluate the effects of ages at slaughtering on carcass characteristics, meat composition and haematology of extensively managed Red Sokoto bucks slaughtered in Abeokuta Metropolis, South-Western Nigeria. A total of twenty four (24) healthy and intact Red Sokoto bucks were sourced from reputable outlets within the metropolis. The animals were grouped into ≤1year, 1-2years and 2-3years of age by the means of dentition before slaughtering. The animals were slaughtered according to the method of severing the jugular veins of the throat and trachea without stunning, meat samples from various parts of the bucks were taken for proximate composition, while the haematological analysis which include: Haemoglobin, Packed cell volume, red blood cell, white blood cell, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and white blood differentials was carried out. Data obtained were subjected to one-way analysis of variance using General linear model (GLM) procedures of SAS. Level of signifi cance was taken at 5% probability, while means were separated using Duncan’s Multiple Range Test of the same statistical package. Results obtained revealed that bucks within 2-3years had highest (p<0.05) values for carcass components such as liveweight (14.63%); Slaughter weight (93.16%); Dressed weight (92.96%); and Chest weight (2.6%), while bucks ≤1year had highest (p<0.05) values for Empty carcass weight (70.29%); Hot carcass weight (54.77%); and Half carcass weight (23.15%). For organs and offal components, bucks within ≤1year had signifi cantly (p<0.05) highest values for all the components except for lungs weight which was highest (p<0.05) for bucks within 1-2years. Different primal cuts of the bucks were signifi cantly (p<0.05) highest for bucks within 2-3years, except for feet weight that was highest (p<0.05) for bucks within ≤1year. For meat composition, meat cuts at different parts from slaughtered bucks within 2-3years had overall best nutritive value. The haematological parameters examined in the study were not signifi cantly (p>0.05) affected by the age of the animals and they fell within the range for healthy animals. The result obtained from this study indicated that Red Sokoto bucks between the ages of 2-3years can be slaughtered for high carcass yield with best nutritive value and good health condition. Research Article


Introduction
In general, the global demand for goat meat is growing [1]. This may have been because goat meat is an important part of the national diet and has a special religious signifi cance in Nigeria. It is also an accepted red meat as part of the cultural heritage and tradition in Asia, Africa and some Mediterranean countries [2]. Moreover, goat meat is characteristically lean, thus rich in nutrients that could attract health conscious consumers. However, the product can vary according to genotype, age, gender and nutrition [3,4].
Haematological tests are important tools for evaluation of physiological and health status of farm animals and almost indispensable in organic farming, where permitted veterinary interventions are strictly regulated and limited in scope. Haematological analyses in farm animals have been extensively discussed as an essential part of clinical examination often pointing to a specifi c differential diagnosis or suggesting a prognosis [5,6]. This haematology have been reported by [7], to be infl uenced by age groups of different breeds of goats. and often the only living source of livelihood of people inhabiting the forest regions or regions not suitable for crop cultivation and cattle production [8]. They can digest and utilize cellulose and hemicelluloses, household waste and other range of feedstuff that are less important to man and other animals. Small ruminant animals also feed on varieties of edible plants; they make use of non-protein nitrogen (NPN) and synthesize most of the amino acid. They perform well on good forages most especially sown pastures [9]. Goats like other ruminants, play an important role in the livelihood of rural people in communal farming systems. Indigenous goats constitute valuable genetic resources because of their ability to adapt to harsh climatic conditions, to better utilize the limited and often poor quality feed resources and their natural resistance to a range of diseases and internal parasites [10]. Nigeria indigenous goats which include West African dwarf, Sahel goats and Red Sokoto goats are more common in the rural areas, with each of the breeds been adapted to a particular geographical location. The West African dwarf goat is adapted to south-west or forest ecological zone, Sahel goat is common to the Sahelian North-West of Africa ecological zone and found in the northern fringes of the country, while the Red Sokoto goats are found in the North-Western Nigeria and are the most popular breed of goats in Nigeria due to their wide acceptance for chevon production.
The Red Sokoto and the Sahel constitute majority of goats slaughtered in Nigeria. A choice between the meats of these breeds and age-related changes in macromolecular composition of their meats will allow for competitive maximization of nutritional and economic advantage [11]. Meat is one of the most important constituents of the human diet as it provides protein, energy, vitamins and minerals. The demand for meat from goat obviously is increasing as seen in major cities of Nigeria. This probably could be as a result of it characteristics fl avour or the advent of several food joints that have them as delicacy in the country. Haematological studies are a useful tool in the diagnosis of many diseases in livestock production and investigation of the extent of damages to the blood. It is important because blood is the major transport system of the body and the evaluation of the haematology parameters will provides vital information on the body response to injuries, cell damage and feed toxicity [12]. The constituent of the haematology usually refl ect the physiological responsiveness of the animal to it external and internal environments which includes; feed and feeding [13]. This study therefore was designed to determine infl uence of ages at slaughtering on carcass characteristics, meat composition and haematology of extensively managed Red Sokoto bucks slaughtered in Abeokuta Metropolis, South-west Nigeria.

Study area
Abeokuta is the capital of Ogun state in south-west, Nigeria. It is located on latitude 7° 07' 03" N and longitude: 3° 18' 23" E.

Experimental animals
A total of twenty four (24) Red Sokoto bucks were purchased from reputable sources within Abeokuta metropolis, South-Western Nigeria. The bucks were within age range of <1year, 1-2years and 2-3year. The age ranges of the animals were determined through their dentitions as described by [14]. Each of the age groups had 8 bucks i.e. 8bucks/age group. Before the bucks were purchased, health status examination of the bucks was conducted by a veterinary doctor for presence of diarrhoea on the anus; the whole body for presence of ecto-parasites like ticks, mites and lice; and overall body condition scores of the bucks among others. At the end of the examinations, only bucks found to be in good state of health were purchased for the study. The management of the bucks before purchase at the points of purchase was that the bucks were fed with cowpea haulms and stovers ad libitum daily after they have gone round to graze on grasses like Panicum maximum; Pennisetum purpureum; and Andropogon spp which are the most prevalent grass species in the city. Clean and drinkable water was also made available to the bucks unrestricted every day. were starved for 12hours before slaughtering. The liveweight of the animals was determined using spring balance before slaughtering. The animals were slaughtered according to the method of severing the jugular veins of the throat and trachea without stunning as described by [15].

Carcass evaluation
After thorough bleeding, the hair was scalded from the skin of the bucks by using warm water, evisceration was done to remove the internal organs and the following measurements f) The carcass was divided into two equal parts along the backbone to get the half carcass weight; g) Also the ribs, forelimbs, hind limbs, chest and scrotum were carefully removed and measured.

Proximate composition of meat collected
Boneless meat cuts were taken from different parts of the carcass such as loin, rib, thigh and fl ank, of the bucks grouped according to ages of the animals as ≤1year, 1-2years,

Data analysis
The experimental design adopted for the experiment was completely randomized design (CRD). Data generated were subjected to one-way analysis of variance using the General linear model (GLM) procedures of Statistical Analysis System [18] to test the effects of age on the carcass characteristics, meat composition and haematological parameters. Level of signifi cance was taken at 5% probability, while means were separated using Duncan's Multiple Range Test of the same statistical package.  [20,14,21]. The results obtained for this study are in agreement with the ones obtained by [15] for the same parameters for sheep fed varying levels of maize and cassava hay under feedlot management. Table 2 shows characteristics of organs and offal of Red Sokoto Bucks slaughtered in Abeokuta metropolis. It was observed that slaughter age had signifi cant effects (p>0.05) on most of the organs and offal weights such as: kidney, lungs, heart, spleen, scrotum and full gut of the bucks between the age groups which may be due to the fact that these organs are early maturing and may not be affected by the age of the animal which is in accordance with the fi ndings of [15] on sheep.

Results and Discussion
Bucks within ≤1years of age had highest (p<0.05) values for all the organs and offals examined, except for lungs weight where bucks within 1-2years recorded highest (p<0.05) value. The difference in gut weights among the age groups may be due to the fact that the capacity of the rumen differs with age and the    [23]. The crude protein from the thigh cut was not signifi cantly different (p>0.05) across the age groups while the crude protein from the rib, loin and fl ank were signifi cantly different (p<0.05) across the age groups which is in agreement with the report of [24]. The crude fat was signifi cantly different (p<0.05) for all the parts examined across the different age groups with the lowest value (0.36%) found in age group 1-2years from the loin and the highest value (0.84%) found in age group 1-2years.
Total ash from the loin was not signifi cantly different (p>0.05) across the age groups, while the total ash from thigh, rib and fl ank cuts were signifi cantly different (p<0.05) across the age groups. 2-3years age group had 1.15% from the thigh cut while lower value of 0.65% was found in the thigh. The NFE was also found to be signifi cantly different (p<0.05) across the age groups for all the cuts. slaughter. This is an indication that the bucks were in good state of health before slaughtering. The PCV is the measure   For meat composition, meat cuts at different parts from slaughtered bucks within 2-3years had overall best nutritive value. Age of the bucks had no effect on the haematology of the animals but were within the normal range reported for healthy goats.
Statement of Animal Rights: All applicable International, National, and Institutional guidelines for the care and use of animals were followed in the conduct of this research.
Informed Consent: Informed consent was obtained from all individual participants included in this study.