Response of supplemental cassava root sievate-cassava leaf meal based diets on carcass and cost benefits of kano brown goats Capra aegagrus

The experiment was conducted to determine the organ weight characteristics, carcass yield and cost benefits of Kano Brown goats fed cassava root sievate and cassava leaf meal (CRSCLM) based diets as supplement to (Pennisetum purpureum) using 36 Kano Brown goats of 8 to 10 months of age. Four diets T1, T2, T3, and T4, were formulated at the levels of 0%, 20%, 40% and 60% CRSCLM respectively in a completely randomized design. Each animal received a designated treatment diet in the morning for 97 days. Feed offered was based on 3.5% body weight per day; the animals in addition were fed a kg wilted chopped P. purpureum later in the day as basal diet to enhance rumination and fine chewing. Results on carcass indices showed significant (p<0.05) response on live weight at slaughter, empty carcass weight, warm carcass weight, dressing percentage, shoulder, leg, loin, end and shank with T4 having relatively best results. The dressing percentage was numerically (49.59%) best at T4. On the offal weights, head and full guts were significantly (p<0.05) improved for T4 and T1 goats. The organ characteristic proved the safety of using CRSCLM through the significantly (p<0.05) lower organ weights at T4 goats. Cost per kg feed, feed cost/weight gain and cost/benefit ratio were positively influenced (p<0.05) at T4 with expected income of 4.79 / 1 invested. It could therefore be concluded that Kano Brown goats fed 60% CRSCLM had the best carcass and organ yields at a reduced feed cost.


INTRODUCTION
Livestock production is an important tool in the economy of developing countries.Goats particularly play an important role in the livelihood of small scale farmers as a major component of livestock mixed farming systems, which produce meat, milk, skin, fiber and manure to large number of low income earners (Ahaotu and Ayo-Enwerem, 2018).The products are however in short supply due to seasonal fluctuation in feed quality and quantity, thus making feeding an important constraint to improved goat production.
The provision of adequate nutrition could thus be a pathway to enhanced goat production.Grasses which are the most abundant basal feed for goats dry up during the dry season thus resulting to highly lignified feed material with very poor digestibility coefficient, low energy and protein values.The complex factor that affects livestock production is nutrition, as feed resources are limited in quantity and quality (Ahaotu, 2018).The systems of goat production in Nigeria are usually characterized by limitations posed by non-availability of year-round feed resources due to prolonged dry season of northern Nigeria ( Aina et al., 2002).This will in turn lead to poor performance of the animals (Katuromunda et al., 2012).This however has encouraged the need for a dry season supplementation to augment for the shortfall in the deficient nutrients so as to meet the nutrient requirements of goats.One of the readily, abundant http://jurnal.unsyiah.ac.id/AJAS and cheaply sourced feedstuff which could be used to formulated a dry season supplement for goats is cassava root sievate and cassava leaf meal due to their high energy, fibre and protein profile.
The supplemental diets must be formulated in such a way not to compromise the nutritional need of the goats, but should be however be at affordable cost.The use of cassava or its by-products in the formulation of supplemental diets for ruminants has been extensively researched.Goats (Oni et al., 2012;Katuromunda et al., 2012;Oni et al., 2017), sheep (Fasae et al., 2015;Fadiyimu et al., 2016) and cattle (Oduguwa et al., 2013) fed with cassava or its by-products showed improved feed intake, nutrient utilization, blood profile, growth rate, carcass and organ characteristics.Cassava root sievate and cassava leaf meal have been identified as an underutilized feed resources for goats, its nutritional quality has necessitated its utilization as goat feed.Cassava leaf meal is a non-conventional feed stuff that is readily available at little or no cost.The root sievate has a high energy and fibre profile which are essential for goats.Cassava and its by products have been however, implicated with anti-nutritional factor majorly cyanide (Morgan and Choct, 2016) which has been reported to affect nutrient availability, blood formation and utilization when not properly processed (Oelker et al., 2009).Thus, the fermentation, drying and further milling employed in this study would perhaps further reduce the anti-nutrients to tolerable level for goats.This experiment was designed therefore to determine the carcass yield, organ weights and economics of production of Kano brown goats fed cassava root sievatecassava leaf meal based diets.

MATERIALS AND METHODS
The experiment was carried out at the Goatery Unit of Animal Production and Health Technology Department, Imo State Polytechnic Umuagwo, Nigeria.Imo State Polytechnic Umuagwo is located at the site is situated between longitudes 7 o 0 1 06 11 E and 7 o 03 1 00 11 and latitudes 5 o 28 1 00 11 N and 5 o 30 1 00 11 N in the humid tropical West Africa (IMLS, 2016).The climate is marked by two seasons.

Experimental feeds
The cassava root sievate and cassava leaf were sourced and harvested within the Imo State Polytechnic Communities, Umuagwo, Nigeria.The cassava root sievate is a by-product of cassava root processing.It was gotten after the processed cassava roots production are peeled or not, washed clean and soaked in clean water for 3-5 days to ferment so as to reduce the hydrogen cyanide level and also to soften the roots to enable sieving.Thereafter, the soaked cassava roots are sieved, the sievate (waste) collected and sundried for about 5 days to reduce the moisture contents and possible anti-nutrients that were not removed during the fermentation process.The cassava leaves were harvested from the Department of Crop Production research and demonstration cassava farms after root harvesting.The both were coarsely milled using hammer mill to encourage fine chewing.The cassava root sievate meal (CRSM) and cassava leaf meal (CLM) were mixed in the ratio of 3:1 and used in the formulation of the experimental diet.Four diets T1, T2, T3, and T4, were formulated.The cassava root sievate-cassava leaf meal (CRSCLM) was included at the levels of 0%, 20%, 40% and 60% for T1, T2, T3, and T4, respectively as presented in Table 1.All feeds and test ingredients were analyzed for proximate compositions using the method of AOAC (2000).

Animal management
Thirty six (36) Kano Brown goats within the range of 8 -10 months of age and averaging 7.19kg in weight were selected from the Imo State Polytechnic goatery farm for this experiment.The goats were randomly divided into four groups of nine animals each with three goats http://jurnal.unsyiah.ac.id/AJAS constituting a replicate.The groups were randomly assigned the four experimental diets (T1, T2, T3, and T4) in a completely randomized design (CRD).
The animals were housed individually in a well-ventilated cement floored pens equipped with feeders and drinkers.Each animal received a designated treatment diet in the morning (8am) for 97 days.Feed offered was based on 3.5% body weight per day; the animals in addition were fed 1kg wilted chopped P. purpureum later in the day (5pm).Regular access to fresh drinking water was made available.

Carcass and organ evaluation
After the 97 days feeding trial, one goat from each replicate was starved of feed for 24 hours and weighed prior to slaughter.The goats were cut at the throat, and then slaughtered by severing the heads at its articulation with the atlas bone.After dressing, the carcasses were weighed to determine the warm carcass weight.This represented the weight of the goats after removal of head, skin, thoracic, abdominal and pelvic contents and the limb distal to the joints.The dressing out percentages were calculated by dividing the warm carcass weight by the live weight prior to slaughter and multiplied by 100%.Other carcass components, organ, guts and muscles were weighed as well.The empty weights were determined by subtracting the weights of the gut contents from the live weights at slaughter.The warm carcasses were divided into two with a saw through the spinal column.The left halves were cut into various parts.The leg/thigh was severed from the attachment of the femur to the acetabulum.The loin consisted of the lumber region plus a pair of ribs and the ends (9 spare ribs and the belly) of six abdominal ribs.The shoulder consisted of the scapula, humerus, radius, ulna, carpals while the sets are made up of the breast and the neck.Each of the cut parts was weighed and doubled in each case before being expressed as a percentage of warm carcass weight.http://jurnal.unsyiah.ac.id/AJAS

Economics of production
The variable cost of feeding the goats considered as the cost of the feed and all other cost (i.e.labour, capital investment and housing) were the same for all the treatments.The cost of processing the cassava root sievate-cassava leaf meal (CRS-CLM) was included as the feed cost.The cost per 100kg feed (#) was determined by the summation of the cost of each feed ingredient used in the formulation per treatment.The cost per kilogramme of feed (#) was determined by dividing the cost per 100kg feed by 100.Total cost of feed (#) was calculated by multiplying total feed consumed by cost per kg of feed and daily feed cost was calculated by dividing total feed cost by the number of experimental days.Feed cost/weight gain (#) was determined by dividing total cost of feed by total weight gain.Cost benefit ratio was calculated by dividing cost/kg live weight by feed cost/weight gain.

Statistical analysis
The results were analyzed using one-way analysis of variance (ANOVA) to determine the means and standard error.Treatment means were compared using Duncan's new multiple range test (Gordon and Gordon, 2004).

RESULTS
The proximate composition of the experimental diets, CRSM, CLM and P. purpureum are presented in Table 2.The dry matter (DM), crude fibre (CF) and gross energy increased with increasing levels of CRSCLM while crude protein (CP), Neutral detergent fibre (NDF) and Acid detergent fibre (ADF) decreased with increasing levels of CRSCLM.Ash, ether extract (EE), Nitrogen free extract (NFE) and hemicellulose failed to follow a specific trend across the treatment groups.Diets had significant (p<0.05)effects on all the carcass parameters (Table 3), except for set that remained significantly (p>0.05)similar across the treatments.T3 had the lowest slaughter weight which significantly (p<0.05)differed from T4.The difference in the slaughter weight may be attributed to lower initial weight of T3 animals or may be due to high final weight observed for T4 goats.T3 showed significantly (p<0.05)lower empty weight in comparison to other treatments.The meat cuts are expressed as percentage warm carcass weight apart from set, were influenced (p<0.05) by the dietary levels.
The fibre fractions (NDF, ADF and hemicellulose) have implication on the digestibility of plants.The NDF, which is a measure of the plants' cell wall contents, is the chemical component of the feed that determines its rate of digestion.The DM, CP, ash, NDF, ADF and hemicellulose were higher in the control, but however compared to the treatment groups.

DISCUSSION
The empty weight (7.75-11.35kg)obtained in this study is lower than 13.09-19.72kgreported by Marques et al. (2014) for Moxotó growing goats, but somehow comparable with 8.1-9.2kg reported by Grum (2010) for Kano brown goats.The warm carcass weight (4.43-7.17kg)obtained in this study is lower than 11.01kg reported by Rodriguez et al. (2014) and higher than 3.40-4.65kgreported by Ifut et al. (2011).
The carcass weights are however in agreement with the findings of Ifut et al. (2011) who reported significant values in warm carcass weights.The values obtained in this study also fell within the range of 2.9-9.81kg reported by Marichal et al. (2003).Ahaotu and Ayo-Enwerem (2008) stated that dressing percentage (DP) is affected by plane of nutrition and other factors such as breed, age and sex.However, the significant (p<0.05)differences observed in this study may be attributed to nutrition, age and slaughter weight of the goats.The dressing percentage obtained in this study however, fell within 38 and 56% baseline reported for goats.This is an indication that the diets were nourishing and supported lean meat deposition across the treatment groups.The effect of nutrition on dressing percentage cannot be over emphasis because changes http://jurnal.unsyiah.ac.id/AJAS in goat diets may improve both the quantity and quality of the goat meat as a final product (Geay et al., 2001).The influence of nutrition, age and slaughter weights has been reported to positively influence dressing percentages in goats.
The meat cut is an important factor in evaluation of meat yield of goat.T4 diet showed a superior shoulder, leg, loin, and shank weights than other treatment groups.This suggested that T4 diet influenced the development of these cut parts better than the other treatment groups.The factors that may have attributed to the variations in the shoulder, leg, loin and shank weights include age, slaughter weight and body condition of the goats.The improved meat cut parts at T4 may be attributed to higher available energy and lower ADF, NDF and lower protein content of the diet.High percentages of crude fibre and roughage with low digestibility could contribute to low dressing percentages which is a function of the meat cuts.Mahgoub et al. (2005) noted that increased level of protein supplement resulted to decrease in the dressing percentage (meat cuts) while increased ME levels resulted to increased carcass weight and DP.
The edible offal weights of Kano brown goats fed CRSMCLM based diets are presented in Table 4. T1, T2 and T4 showed significantly (p<0.05)superior head values than T3 goats.Table 5 summarizes the organ yields of Kano brown goats fed purpureum supplemented with CRSM-CLM based diets.The significant (p<0.05)value observed in this present study for head is in agreement with Ifut et al. (2011) for Kano brown goats.The full gut also differed significantly (p<0.05) with T3 having the lowest value.The result however, is in disagreement with Anbarasu, (2004) who reported that gut fill could constitute 20 -22% of live weight.
There was significant difference (p<0.05) in the organ yields of the treatments evaluated except for spleen weights.It is a common practice in feeding trials to use weight of some internal organs like kidney and liver as indicators of anti-nutritional factors (Ahaotu and Ayo-Enwerem, 2008).Ahaotu (2018) reported that if there is any toxic element in feed samples used in feeding trial, abnormalities will arise because of increased metabolic activities of the organ in an attempt to reduce these toxic elements or anti-nutritional factors to non-toxic forms.
The cost benefit evaluation of Kano brown goats fed CRSCLM in their diets is presented in table 6.The cost of production per 100 kg feed, cost per kg of feed, total cost of feed and daily feed cost differed (p<0.05)significantly across the treatment groups and tended to decrease with increasing levels of CRSCLM inclusion in the diets.As the level of inclusion of CRSCLM in the diets of Kano brown goats increased from 0% (T1) 0% to 60% (T4), the overall cost of feed decreased.The feed cost/weight gain showed significant (p<0.05)values decreasing with increasing levels of CRSCLM.The decrease in feed cost maybe attributed to the inclusion of locally non-competitive and very cheap unconventional feed (CRSCLM) in the diets of Kano brown goats.This is in agreement which earlier reports by Katuromunda et al. (2012) who reported a reduced feed cost when Moringa oleifera leaf meal (locally and cheaply sourced alternative) was included in the diets of Kano brown goats.From the result, it could be deduced that CRSCLM also enhanced weight gain which further resulted to lower feed cost per kg weight gain.A similar result was reported by Katuromunda et al. (2012).This further entail that inclusion of some potential locally cheap feed stuffs do not only reduce feed cost, but also increases weight gain.Cost benefit ratio was best for T4.This was agreement with the results of earlier studies by (Ogundipe et al., 2003) who reported that the need to lower feed cost in order to produce affordable meat and other animal products for the populace cannot be over-emphasized in the face of dwindling standard of living.The result demonstrated the qualitative benefits and financial returns of using CRSCLM diets; with T4 having the highest ratio and T1 had the lowest value.This entails an expected benefit of # 4.79 for every # 1 in cost for T4 diet.This result suggested that the optimum level of inclusion of CRSCLM in the diet of Kano brown goat may not have been attained and perhaps incremental level beyond 60% inclusion may still yield higher cost benefit ratio beyond the value recorded for T4 in this trial.
The proximate composition of P. purpureum in this study is in comparison with the values reported by Onyeonagu and Eze (2013) and Amaefule and Elendu (2010) for the same forage.The cassava leaf meal (CLM) is comparable with the DM, CP, ash and NFE values reported by http://jurnal.unsyiah.ac.id/AJASAllen (1984) and Akinfala et al. (2002).The crude protein content of the CRSM is below the acceptable 7% CP for ruminant performance as recommended by Ahaotu (2018) and 8% suggested by Ahaotu and Ayo-Enwerem, (2008) for ruminal function.
The NDF comprises mainly the cell wall fraction of forages and roughages and includes a complex matrix of lignin, small amounts of protein, and various polysaccharides, Ocheja et al., (2014) noted that the higher the NDF, the lower the plant's digestible energy.The values obtained for the CRSM may imply moderate cell wall content, moderate digestible energy and DM intake.The ADF consist mainly the lignin and cellulose.Hemicellulose has been reported to be more digestible than cellulose (Ihezuo et al., 2013).The reportedly lower values of the fibre fractions are in agreement with the findings of Ajeigbe et al. (2011) for the same cassava by product.The high energy value reported for the CRSM is in agreement with Khampa et al. (2009) who noted that cassava roots contain high levels of energy and have been used as a source of readily fermentable energy in ruminant rations.The high dry matter value reported is favourably compared with the values of Boonnop et al. (2009).The proximate composition of the experimental diets revealed that the crude protein and the energy requirements are within the ranges reported for goats (Ahaotu and Ayo-Enwerem, 2008).

CONCLUSIONS
This study revealed that the inclusion of cassava root sievate -cassava leaf meal in the diets of Kano brown goats resulted to superior carcass and organ weights and lower production cost with high return on investment.It further revealed that the processing methods used in this study reduced the level of anti-nutritional factors (HCN) to a tolerable level by Kano brown goats.It was therefore concluded that Kano brown goats fed 60% cassava root sievate -cassava leaf meal had the best carcass and organ yields at a reduced feed cost.

Table 1 .
Composition of the experimental diets for Kano Brown Goats

Table 2 .
Proximate composition of the experimental diets, cassava root sievate meal, cassava leaf meal and Pennisetum purpureum

Table 3 .
Carcass characteristics of kano brown goats fed cassava root sievate-cassava leaf meal based Diets

Table 4 .
Offal characteristics of kano brown goats fed cassava root sievate-cassava leaf meal based diets

Table 5 .
Organ characteristics of kano brown goats fed cassava root sievate-cassava leaf meal based diets

Table 6 .
Cost benefit analysis of kano brown goats fed supplemental cassava root sievate -cassava leaf Meal