Growth Performance and Carcass Characteristics of West African Dwarf Bucks Fed Different Forms of Processed Guinea Grass (Panicum Maximum)

Introduction

Small ruminants form an integral part in the livestock economy production system in Nigeria.¹ They provide animal protein, fibre and skin, food security and a stable household income. They also have whole range of advantage over large ruminants in terms of adaptation to and interaction with the environment. This suggests the relative importance of goats within the livestock economy.

In Nigeria, goats are significant in the socio-economic life of the people as they contribute about 35% of the animal meat supply² This figure may be higher if the animals processed in slaughter houses for which records are not available are included.² In most tropical countries, ruminant animals are maintained on native pastures and other feed resources as their main source of nutrients.³ Hence, the use of pasture grass has been advocated for small ruminants.

However, the dry season feeding of ruminants especially goats in Nigeria has always been a challenge to farmers since good quality pastures are scarce, hence, performance of these animals are seriously impaired. The situation becomes worst during this period as animals are unable to meet their protein and energy from available poor quality herbage with consequent marked weight loss and reduced productivity of goats.⁴ Hence, the need to process this feed resource to ensure the availability of feed all year round and prevent loss of weight associated with seasonality of forage. Panicum maximum (Guinea grass) is one of the most naturally occurring grasses in the tropics and subtropics of Africa which has high yield and regenerating ability. They are very responsive to nitrogenous fertilizer and highly palatable to livestock at all stages of growth which makes it one of the best fodder grasses.⁵

Silage and hay can be prepared from guinea grass.It can also be used in cut and carry system of feeding.⁶ reported that guinea grass can be managed as long- term grass if is consistently grazed .It regrows to 2.5 leaves/ tillers during the rest period. Good quality silage can be obtained during pre-flowering stage which can be made into silage and hay.⁶ Processing of grasses into hay and silage have been identified as a cheap way of ensuring feed availability without season.

Dried forages can be used as hay for ruminants. Silage is the most succulent feed produced as a result of controlled fermentation of fresh forage when stored in an air tight container under anaerobic condition. Silage can be stored for months or years and can be used when required.⁷

Silage making involve cutting grass at pre-flowering stage and legumes at initial flowering. This is the stage when the plants abound in protein, carbohydrates and mineral salt and vitamins. The plant cut were ensiled quickly, packed in a tight plastic bag and sealed appropriately to avoid pocket of air.⁸ This review article therefore is based on using different forms of processed Panicum maximum on the performance and carcass characteristics of West African dwarf bucks.

Materials and Method

Experimental Site

The experiment was carried out at the goat unit of the Teaching and Research farm of the Department of Animal Science, Akwa Ibom State University, Obio Akpa Campus. The area lies between latitude 4^o30יN and 5^o30יN and longitudes 7^o30יE and 8^o00יE of the Greenwich Meridian. The area is in the humid tropical region, characterized by two seasons, rainy and dry, which last respectively from March to November and from November to March. Other climatic parameters are; heavy rainfall of 2000-2500 mm in the wet season, annual temperature range of 24^oC-30^oC, and relative humidity range of 75-79 %.⁹

Experimental Animals and Management

Twelve (12) West Africa Dwarf bucks of age between 6 and 8 months with mean initial weight of 7.26 kg were used. The animals were bought from rural small holder farmers within Obio Akpa village in Akwa Ibom State. They were given anti-stress on arrival and were housed in a concrete floored pen with open sides covered with thick wire mesh for ventilation.

The bucks were quarantined for a period of 14 days, and were fed silage, fresh fodder, wilted fodder and hay in addition to concentrates. Long acting antibiotic (Oxytetracycline HCL 20%) injection was administered intravenously and repeated after four days to take care of any infection that may arise. One bolus of albendazole was administered orally to each animal for the control of endo-parasites and ivomectin injection at 2 ml/goat which was administered for the treatment and prevention of both ecto and endo parasites. Vaccination was done against kata or peste des petits ruminants (PPR).

At the beginning of the experiment, the animals were allotted to different treatments after balancing for weight in each treatment in a Complete Randomized Design (CRD) experiment.

Clean water was given ad-libitum on a daily basis for 56 days.

Experimental Diet

The experimental diet was basically Panicum maximum. This was offered to the animals in different forms viz:  wilted, cut and carry (fresh), silage and hay, designated as T₁, T₂, T₃ and T₄ respectively.

Hay Preparation

Panicum maximum forage was cut around the University vicinity at pre-flowering stage, chopped at 3 cm long, sundried for 3 days, bailed and stored for the experiment.

Silage Preparation

The grass was cut at pre-flowering stage chopped at about 3cm in length, loaded in a black plastic bag and pressed to ensure compaction and then sealed to ensure air tight or anaerobic conditions for 21 days. After 21 days, the ensiled materials were opened and samples were analyzed for proximate fractions. Black plastic bags or pressed bag method employed by¹⁰ was adopted for silage preparation.

Wilted Forage

Panicum maximum was cut and wilted for 48 hours under room temperature 25^o C and used for the experiment.

Data Collection

Data on voluntary feed intake was recorded every morning for each animal by subtracting feed refusals from the amount given on the previous day. Data emanated from the experiment was used to calculate weight gain, average daily weight gain and feed conversion ratio for 56 days.

Carcass Evaluation

A total of eight goats comprising two goats per treatment, were randomly selected, starved for 24 hours and then used for carcass evaluation. The animals were severed through the jogular. They were hung upside down to allow proper removal of blood .Carcass evaluation was carried out for the meat cuts.

Table 1: Composition of the Basal Diets.

	T1	T2	T3	T4
PKC	30	30	30	30
BDG	37.5	37.5	37.5	37.5
WO	30	30	30	30
BM	2.0	2.0	2.0	2.0
Salt	0.5	0.5	0.5	0.5
Total	100	100	100	100
Calculated Protein	17.4	17.4	17.4	17.4
Calculated Energy(Kcal-1/Kg)	2072.5	2072.5	2072.5	2072.5

T₁ = Wilted Panicum maximum;
T₂= Fresh (Cut and carry) Panicum maximum;
T₃ = Ensiled Panicum maximum;
T₄= Panicum maximum hay.

Statistical Analysis

The data collected were subjected to analysis of variance procedures. Significant means were separated using Duncan Multiple Range Test.¹¹

Results and Discussion

Table 2: Proximate Composition of Experimental Diets.

Nutrients	T1	T2	T3	T4	Conc.	SEM
DM (%)	52.48c	30.4d	23.45e	95.86a	86.06b	1.04
CP (%)	13.10bc	13.81b	12.31cd	11.38a	20.94a	0.36
CF (%)	4.55b	4.44b	4.44b	4.61b	6.58a	0.36
EE (%)	4.60a	5.24a	4.44a	1.46b	1.09b	0.40
Ash	6.52b	7.34b	6.43b	6.82b	9.83a	0.35
NFE	75.29a	74.66a	72.39a	75.73a	61.56b	1.13
Energy (Kca/Kg)	375.90ab	377.70a	370.77ab	361.55ab	339.81b	9.59

^abcde means on the same row with different superscripts are significantly different (P<0.05).
T₁ = Wilted Panicum maximum;
T₂ = Fresh (Cut and carry) Panicum maximum;
T₃ = Ensiled Panicum maximum;
T₄ = Panicum maximum hay;
SEM = Std error of mean.

Table 3: Growth Performance of Goats Fed Different Forms of Processed Panicum maximum.

Parameters	T1	T2	T3	T4	SEM
Initial body Wt (Kg)	7.72	7.50	7.14	6.67	0.76
Final body Wt (Kg)	8.94	8.67	7.90	7.48	0.78
Daily Concentrate Intake (g/day)	135.18ab	125.34b	167.32a	139.29ab	0.57
Daily Forage intake (g/day)	607.78a	634.46a	396.96b	345.18b	1.54
Total Daily Feed intake (g/day)	742.96a	759.80a	564.28b	484.47c	3.37
Daily weight gain (g/day)	21.78	20.89	13.57	14.46	3.49
FCR	34.11	36.37	41.58	33.50	10.09

^abc means on the same row with different superscripts are significantly different (P<0.05).
T₁ = Wilted Panicum maximum;
T₂ = Fresh (Cut and carry) Panicum maximum;
T₃ = Ensiled Panicum maximum;
T₄ = Panicum maximumhay;
SEM = Std error of mean.

The growth performance of goats fed the experimental diets is shown in Table 3. Final body weights were 8.94Kg, 8.67Kg, 7.90Kg, 7.48Kg for goats fed wilted Panicum maximum(T₁), Fresh Panicum maximum (T₂), Ensiled Panicum maximum(T₃) and Panicum maximum hay (T₄) respectively. There were no significant differences (P>0.05) among the treatments. Mean daily concentrate intake showed significant differences (P<0.05) among treatments. Goats placed on wilted Panicum maximum(T₁) (135.18g/day) and Panicum maximum hay (T₄) (139.29g/day) were similar in concentrate intake. Goats fed ensiled Panicum maximum (T₃) (167.32g/day) had higher value of concentrate intake. The observed intake were lower than the range (525.14-546.26g/day) reported by.¹² Goats fed wilted Panicum maximum (T₁) (607.78g/day) and fresh Panicum maximum (T₂) (634.46g/day) had similar intake but differed from goats placed on ensiled Panicum maximum (T_3­) and Panicum maximum hay (T₄).

Daily dry matter intake (DMI) differed (P<0.05) significantly among treatments. Dry matter intake of goat on wilted Panicum maximum and Fresh Panicum maximum were similar and differed from DMI of goats placed on ensiled Panicum and Panicum hay. The dry matter intake values observed were higher than the ranges 235.00-388.82g/day and 265.10-333.24g/day.¹³

Daily weight gain did not significantly differ (P>0.05) among treatments. The heavier weight gain was observed in goats fed wilted Panicum maximum (T₁). The values obtained in this study were lower than that reported by¹⁴ who reported a range of 31.27g-42.26g for WAD goats. The heavier weight gain of goats fed wilted Panicum maximum (T₁) may be due to high DMI and better feed utilization.

Feed conversion ratios did not show significant differences (P>0.05) among treatments. The feed conversion ratios of goats except for goats on ensiled Panicum maximum (T₃) have agreed with study of¹⁵ who reported the range of 25.25-36.52. The feed conversion ratio exhibited by goats fed wilted Panicum maximum (T₁) could be attributed to higher feed utilization.

Carcass characteristics of goats fed the experimental diets is presented in Table 4. The live weight at slaughter were 7.85Kg, 7.70Kg, 5.40Kg and 6.20Kg for goats placed on wilted Panicum maximum (T₁), Fresh Panicum maximum (T₂), Ensiled Panicum maximum (T₃) and Panicum maximum hay (T₄) respectively.  Goats fed wilted Panicum maximum produced higher value of live weight which did not differ (P>0.05) from other treatments. For bled weight, goat on fresh Panicum maximum(T₂) have higher value (7.40Kg) compared to 6.90Kg, 5.15 and 5.85Kg for treatment 1,3, and 4 respectively. Bled weight did not show significant difference (P>0.05). Heavier dressed weight was produced by goats fed wilted Panicum maximum but did not significantly differ (P>0.05) from other treatments. The dressed weights obtained were lower than the range (3.86-4.65Kg) reported by.¹⁶ Higher value was obtained in goats placed on wilted Panicum maximum (T_1­) closely followed by goats fed fresh Panicum maximum, the least dressing percentage was observed in goats fed ensiled Panicum maximum. Values obtained were in agreement with the reports of.¹⁶ Goats fed wilted Panicum (640.37g) had the highest value of shoulder; the least was produced by goat on ensiled Panicum maximum (410.15g). Thigh of goats fed fresh Panicum maximum weighed heavier, and the least weight was produced by goat on ensiled Panicum maximum (360.00g). There were significant differences (P<0.05) for weight of sets. Goats fed wilted Panicum (T₁) (575.41g) and Panicum hay (T₄) (437.00g) produced similar weight of sets. The highest value (1064.00) was obtained by goats fed fresh Panicum maximum. The values obtained were higher than that obtained by¹⁵ who reported 365-478g for WAD goats fed bambaranut based diets. Highest and least values of ends were obtained by goats fed wilted (T_1­) Panicum maximum and ensiled (T₂) Panicum respectively. The offals were not significantly (P>0.05) different. Fresh Panicum maximum (T_2­) (630.00g) produced heavier weight of skin (630.00g). The least weight of skin was observed in goats fed Panicum maximum hay (T_4­). The weight of skin obtained fell below the range (9.73-13.14%) reported for goats fed pigeon-pea cassava peel meal for WAD goats fed pigeon pea-cassava peel based diets.¹⁷

Heavier weight of full gut was observed in goats fed fresh Panicum maximum (T_2­) (2.60Kg), the least weight was obtained by goats fed ensiled Panicum maximum (T_3­) (1.72Kg). These values were higher than those obtained by.¹⁷ Gut content may constitute up to 20%of the liveweight of goats depending on how long the animal was fasted before slaughter.¹³ The result revealed that goat fed with any form of preserved forage does not have effect on its dressing percentage and formation of any body part. Lungs weight for all treatments were similar except for goats fed ensiled Panicum maximum which differed (P<0.05) significantly. The appreciable bone to lean ratio was obtained by goats fed fresh. Panicum maximum (T₂). The range 0.33-0.47 fed above the range (0.28-0.35) reported by.¹⁸ The result showed that Panicum maximum preserved in any form have no effect on the conversion of forage into meat.

Table 4: Carcass Yield of WAD Bucks Fed Different Processed Forms of Panicum maximum Treatments.

Parameters	T1	T2	T3	T4	SEM
Live Wt (Kg)	7.85	7.70	5	6.20	0.96
Bled Wt (Kg)	6.90	7.40	5.15	5.85	0.95
Dressed Wt (Kg)	2.80	2.71	1.75	2.14	0.46
Dressing %	35.62	35.43	32.08	34.63	1.79
Shoulder (g)	640.37	530.29	410.15	452.00	1.06
Thigh (g)	547.71	597.76	360.00	530.00	1.45
Loin (g)	575.26	445.23	345.12	365.00	1.46
Sets (g)	575.41ab	690.00a	380.19b	437.00ab	1.02
Ends (g)	425.22	420.11	240.35	390.00	0.95
Diaphragm (g)	50.20	30.16	15.11	35.31	0.35
Head (g)	600.00	750.00	600.00	595.00	4.56
Skin (g)	550.00	630.00	500.00	450.00	2.63
Feet (g)	250.00	250.00	300.00	250.00	1.12
Full gut (Kg)	2.15	2.60	1.72	2.45	0.47
Empty gut (Kg)	0.53	0.75	0.55	0.72	0.20
Liver (g)	120.00	132.50	97.50	107.50	0.49
Heart (g)	35.00	35.00	32.50	37.50	0.24
Spleen (g)	10.00	15.00	15.00	12.50	0.31
Lung (g)	60.00a	72.50a	35.00b	77.50a	0.38
Bone to Lean Ratio	0.39	0.33	0.63	0.43	0.20

^abc means on the same row with different superscripts are significantly different (P<0.05).
T₁ = Wilted Panicum maximum;
T₂ = Fresh (Cut and carry) Panicum maximum;
T₃ = Ensiled Panicum maximum;
T₄ = Panicum maximum hay;
SEM = Std error of mean.

Conclusion

The use of processed Panicum maximum in any form has no negative effect in the conversion of forage into meat and formation of any body part. The best performance of WAD goats placed on wilted and fresh Panicum maximum in terms of dry matter intake and weight gain makes it a diet of choice for fattening and reproduction. In line with the results from this research, the following inferences were made;

Wilted and fresh Panicum maximum are recommended for fattening and reproduction of West African Dwarf goat production.

Panicum maximum processed as silage and hay can be used in combination as maintenance ration for WAD goats in the tropics.

Acknowledgement

I wish to acknowledge the contributions from the Department of Animal Science laboratory, Akwa Ibom State University. Most of the analyses were carried out in this laboratory.

Sponsorship

The manuscript has no sponsorship apart from authors’ contributions.

Conflict of Interest

Authors declare no conflict of interest.

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