Citation of this paper

Evaluation of grasshoppers as a protein source for improved indigenous chicken growers

E S Nginya, J O Ondiek, A M King’ori and J M Nduko¹

Department of Animal Sciences, Egerton University, P O Box 536, 20115 Egerton, Kenya
shiloeunice84@gmail.com
¹ Department of Dairy, Food Science and Technology, Egerton University, P O Box 536, 20115 Egerton, Kenya

Abstract

The nutrient composition of three edible acrididae species was studied. Wild edible grasshopper (Ruspolia nitidula, ‘nsenene’), desert locust (Schistocerca gregaria) and reared African grasshopper (Acanthacris ruficornis) were used to determine the effects of substituting grasshopper meal (EG) for fishmeal (FM) on growth, digestibility, carcass characteristics, and meat sensory attributes of improved indigenous chicken (n=150). Grasshopper meal (EG) substituted fishmeal at 0 (EG0), 25 (EG25), 50 (EG50), 75(EG75) and 100 % (EG100) in grower diets. A completely randomized design was used with 30 birds per treatment, 6 per cage (3 pullets and 3 cocks). The crude protein content of FM was higher than that of insect meal, but was similar among the insect meals. Feed intake decreased with increasing levels of EG but the daily weight gain was similar. The feed conversion ratio tended to improve with increasing replacement of fish meal by grassshopper meal. Carcass characteristics were not affected by the treatments. Sensory attributes of meat appeared to be improved slightly by feeding grasshopper meal. Grasshopper meal diets had higher crude protein digestibility than the cotrol with fish meal. These results indicate that grasshopper meal could be used as a substitute for fishmeal in poultry diets..

Key words: alternative, digestibility, fishmeal, insects, poultry, sustainable

Introduction

Farming of improved indigenous chicken has been on the rise among Kenyan famers for income generation and production of meat and eggs (King’ori et al 2010). Despite these benefits farmers face a major challenge of high cost of feed ingredients especially those rich in protein (Magothe et al 2012). Fish meal is expensive, competitive and scarce.

Insects (Acrididae species) have been a major component in the diets of poultry, especially in their natural habitat (Rumpold and Schlüter 2013, Aman et al 2016) and have high nutritive value (Moreki et al 2012). This study aimed to determine the nutritive value of three Acrididae species compared with conventional fishmeal (Rastrineobola argentea) in the diets of improved indigenous chicken. The Acrididae included; reared desert locust (Schistocerca gregaria), reared African grasshopper (Acanthacris ruficornis), and edible grasshopper (Ruspolia nitidula, also known as ‘nsenene’) acquired from the wild.

Materials and methods

Grasshopper collection

African grasshoppers were collected in Naivasha, Gilgil, and Subukia, sub counties in Nakuru county and Kabarnet in Baringo county. Capturing was done early morning using entomological sweep nets. Grasshoppers from Subukia sub County were reared at Egerton University, Njoro campus, in aluminum/glass cages measuring 50cm x 50cm x 60cm. The desert locust was collected from Lodwar, Turkana County, and reared on kales, wheat sprouts and wheat pollard. Edible grasshoppers were bought from grasshopper vendors in Katwe market in Kampala, Uganda. They were prepared by hot water treatment (boiling) and sun drying. The insects were identified at the National Museum of Kenya.

Experimental design

Five iso-nitrogenous diets were formulated with "edible grasshopper" meal (EG) substituting fishmeal at 0, 25, 50, 75 and 100 %. Fishmeal was bought in Nakuru town and Mbita fish market in Homa Bay County, Kenya.

The diets (Table 3) in mash form were formulated to meet the nutritional requirements of improved indigenous chicken (Kenya Agricultural and Livestock Research Organization). Improved indigenous (Kienyeji) chickens four weeks old were procured from KALRO, Naivasha. They were allocated to the five treatments in a completely randomized design replicated five times in pens measuring 1x3m, each with six growers (3 cockerels and 3 hens).

Experimental birds and management

The house was dusted to control external parasites and the floor covered with clean, disinfected, wood shavings as litter. The pens were in a tent house which had 1m high drop down windows for ventilation. Routine management and vaccination were done according to guidelines by KALRO. The chickens received a commercial feed until 10 weeks old, and had 7 days adaptation period to the test diets before data collection. Feed and water were provided ad libitum. The experiment lasted ten weeks.

Digestibility trial

Fifteen improved indigenous chickens (14 weeks-old) were randomly selected and allocated to the five dietary treatments. The chickens were weighed and placed in individual cages. After 7 days adaptation, feed intake was recorded and excreta was collected over a 24h period. The excreta was weighed and chilled immediately for laboratory analysis.

Carcass evaluation

At the end of the feeding trial, four chicken from each of the 5 dietary treatments were randomly selected and fasted (but offered water) for 12h before slaughter. After evisceration, they were separated into different parts (Table 5).

Sensory evaluation

Skinless breast and thigh were boiled in different pots without addition of any spice or salt for 30 minutes. The cooked breast and thigh meat were cut into cubes, wrapped in aluminum foil and placed in sealed plastic containers, and labeled with three random digit codes. They were separately served warm (35^oC).

Twelve trained tasters were given instructions on a score sheet. Sample presentation was completely randomized across all tasters who evaluated the meat for color, flavor, juiciness, tenderness and after-taste on a 7-point hedonic scale. A score of 1 represented “dislike very much” and a score of 7 “liked very much”.

Laboratory analyses

Proximate analysis of insects, fishmeal, diets and excreta was done following AOAC (2000) procedures. . Mineral analysis was done using atomic absorption spectrophotometer.

Data analysis

Data were subjected to Analysis of Variance using the General Linear Model option of SAS (2009). Means were ranked using the Tukey pair-wise comparison test at 5% level of significance.

Results

Chemical composition

The insect meals had similar levels of protein and ash, which were lower than for fishmeal (Table 1). By contrast, EE, CF and gross energy were higher than in fishmeal. Fishmeal had higher levels of macro elements compared to the insect meals (Table 2).

Table 1: Mean values for proximal analysis of the three edible insect meals and fish meal
	% in DM				kcal/kg DM
	Ash	EE	CP	CF	GE

AG	6.40^b	18.8^b	50.5^b	15.3^b	5240^b
DL	6.00^b	20.5^a	50.9^b	16.5^b	5300^b
EG	5.50^c	21.4^a	52.0^b	17.7^a	5850^a
FM	14.8^a	4.90^c	56.6^a	1.60^c	4360^c
SEM	0.30	0.20	0.50	0.20	13.0
p	<0.001	<0.001	<0.0002	<0.001	<0.001
AG=African grasshopper, DL= Desert locust, EG= Edible grasshopper, FM= Fishmeal ^abcd Means in the same row having different superscripts differ at p< 0.05

Table 2: Mean values for mineral content (ppm) of the three edible insects.
	AG	DL	EG	FM	SEM	p

Macro minerals
Phosphorus	153^c	160^b	142^d	541^a	0.59	<0.001
Potassium	344^b	310^c	250^d	370^a	0.89	<0.001
Calcium	146^b	101^d	110^c	249^a	0.69	<0.001
Magnesium	56.4^b	13.3^c	5.0^d	103^a	0.37	<0.001
Micro minerals
Iron	32.2^b	22.5^c	0.70^d	61.3^a	0.42	<0.001
Copper	5.30^a	3.20^b	1.80^c	3.90^b	0.33	<0.001
Zinc	22.5^c	23.6^b	32.8 ^a	32.1^a	0.27	<0.001
Manganese	1.40^b	1.50^b	1.40^b	7.10^a	0.09	<0.001
AG=African grasshopper, DL= Desert locust, EG= Edible grasshopper, FM= Fishmeal ^abcd Means in the same row having different superscripts differ at p< 0.05.

Table 3: Composition of the experimental diets on “% air-dry” basis
Ingredients	EG0	EG25	EG50	EG75	EG100

Maize grain	40.0	40.0	40.0	40.0	40.0
Maize germ	6.00	6.00	6.00	6.00	6.00
Wheat pollard	24.0	24.0	24.0	24.0	24.0
Soybean meal	10.0	10.0	10.0	10.0	10.0
Fishmeal	10.0	7.50	5.00	2.50	0.00
Grasshopper (EG) meal	0.00	2.50	5.00	7.50	10.0
Vegetable oil	1.50	0.50	0.00	0.00	0.00
Limestone	6.00	6.00	6.00	6.00	6.00
DCP	3.50	3.50	3.50	3.50	3.50
Premix#	0.30	0.30	0.30	0.30	0.30
Common salt	0.20	0.20	0.20	0.20	0.20
Coccidiostat	0.03	0.03	0.03	0.03	0.03
Total	100	100	100	100	100
Chemical composition , % on DM basis
Crude protein	15.7	16.0	16.0	16.0	15.9
Ether extract	4.00	4.20	5.70	5.80	8.10
Crude fibre	5.30	5.90	5.70	7.20	6.80
Dry matter, % in air-dry	90.6	90.4	90.3	90.0	90.0
#Content per 2.5 kg: 8000000 IU of Vit.A, 2000000 IU of vit.D3, and 3000mg of Vit. E, 2000 mg of Vit. K3, 3500mg of Vit. B2,6600mg of Pantothenic Acid,20000 mg of Niacin, 550 mg of Folic Acid, 6mg of Vit. B12, 200000 mg Choline Chloride, 350 mg 0f Lysine, 120 mg of Methionine,63000mg of Manganese, 23000 mg of Iron, 63000 mg of Zinc, 14000 mg copper, 1000 mg of Cobalt, 2000 mg of Iodine, 100 mg of Selenium and 12000 mg BHT.

Daily feed intake was reduced when the grasshopper meal exceeded 25% replacement of the fish meal (Table 4) but there were no consistent effects on live weight gain. There were indications that feed conversion imroved with increasing proportions of grasshopper meal replacing fish meal. Protein digestibility appeared to increase with increasing proportionsof insect meal in the diet.

Table 4: Mean values for feed intake, LW gain, feed conversion and digestibility coefficients in chickens fed diets with fishmeal replaced by grasshopper meal
Parameter	EG0	EG25	EG50	EG75	EG100	SEM	p

DM intake, g/d	117^a	116^a	106^b	109^b	108^b	1.30	<0.001
Initial weight, g	991	975	970	953	997	24.9	0.74
Final weight, g	2185	2222	2173	2146	2136	29.1	0.28
Daily gain, g	17.1	17.8	17.2	17.0	16.3	0.90	0.82
DM feed conversion	3.64^a	3.55^ab	3.33^b	3.45^ab	3.44^ab	0.06	<0.001
Apparent digestibility, %
Crude protein	93.6^d	94.2^cd	94.6^c	96.3^b	97.4^a	0.2	<0.001
Ether extract	88.8^c	92.7^b	95.2^a	65.2^e	81.6^d	0.3	<0.001
Means in the same row with different superscripts differ at p< 0.

There were no differences among carcass traits (Table 5). Intestine weight was higher when the grasshopper meal replaced all the fish meal.

Table 5: Mean values for the carcass weights of chicken fed diets with grasshopper meal as a replacement for fishmeal.
	EG0	EG25	EG50	EG75	EG100	SEM	p

Live weight, g	2265	2313	2209	2078	2334	98.2	0.40
De-feathered weight, g	1814	1904	1817	1713	1871	90.7	0.58
Eviscerated carcass, g	1509	1555	1421	1368	1460	85.3	0.64
Dressing weight (%)	66.7	66.9	64.3	65.5	62.2	1.7	0.45
Breast, g	379	374	341	316	359	30.2	0.58
Thigh and drumstick, g	482	502	465	451	468	29.7	0.78
Whole wings, g	182	187	177	174	169	9.2	0.71
Head and legs, g	142	153	138	131	141	7.5	0.37
Liver, g	36.5	36.0	30.8	36.0	42.8	3.7	0.52
Gizzard- empty, g	46.0	51.5	45.3	49.3	55.5	4.6	0.53
Heart, g	11.5	11.5	12.5	12.8	13.3	1.3	1.00
Spleen, g	3.8	2.8	4.3	3.0	3.3	0.4	0.21
Viscera/ intestines, g	137^b	171^ab	126^b	138^b	203^a	15.1	0.01
Abdominal fat, g	33.5	19.5	33.7	38.3	33.0	22.8	0.62
Estimated feather, g	309	255	254	233	322	46.9	0.62
^ab Means within the same row with different superscripts differ at p<0.05

The breast and thigh meat did not differ among the treatments in color, flavor, juiciness, tenderness, after-taste and overall acceptability (Tables 6 and 7). There was a tendency (R² = 0.29 and 0.39) for “overall acceptability” of breast and thigh meat to increase with level of insect meal (Figure 1).

Table 6: Mean values for hedonic ranking of sensory attributes of cooked breast (b) meat of chickens.
	Color	Flavor	Juiciness	Tenderness	Aftertaste	Acceptability

EG0	4.25	4.13	3.92	4.46	4.08	4.10
EG25	3.77	4.23	4.19	4.54	4.00	4.40
EG50	4.33	4.29	4.13	4.39	4.13	4.25
EG75	4.37	4.67	4.38	4.71	4.46	4.46
EG100	3.91	4.38	4.08	4.46	4.54	4.35
SEM	0.26	0.24	0.25	0.26	0.17	0.24
p	0.19	0.15	0.71	0.81	0.07	0.70

Table 7: Mean values for hedonic ranking of sensory attributes of cooked thigh meat of chickens.
	Color	Flavor	Juiciness	Tenderness	After-taste	Acceptability

EG0	4.39	4.7	4.69	5.04	4.4	4.85
EG25	4.91	4.94	4.83	4.69	4.6	4.77
EG50	5.25	5.41	4.92	5.08	5.13	5.22
EG75	5.1	5.29	4.92	4.75	4.79	4.79
EG100	4.87	5.17	5.06	5.42	5.1	5.25
SEM	0.26	0.24	0.25	0.26	0.17	0.24
p	0.19	0.15	0.71	0.81	0.07	0.7

Figure 1: Relationship between overall acceptability of breast and thigh meat from
chickens and level of edible grasshopper meal (EG) in the diet

Discussion

The proximate analysis (Tables 1 and 2) indicates that the three sources of grasshopper meal can replace fish meal in meeting the requirement of protein, fat and minerals for poultry feed formulation.

The feed intake was negatively correlated with the inclusion level of insect meal in the diets which could be attributed to the higher fat content of the grasshopper meal (Table 3) (Engberg 2015). The decreasing feed intake with grasshopper meal inclusion in the diet was similar to that reported by Adeyemo et al (2007), Okah and Onwujiariri (2012), and Brah et al (2018), who fed desert locust meals, maggot meal and to broilers respectively, and observed decreasing intake with increasing inclusion.

The tendency for improved sensory attributes with increasing diet concentration of grasshopper meal is consistent with the findings of Sun et al (2013) who concluded that meat from chickens fed diets with grasshopper meal was preferred more than meat from chickens fed commercial feeds.

Conclusions

The inclusion of grasshopper meal in diets of local chickens improved feed conversion and protein digestibility.
The carcass characteristics of the meat were not affected by the inclusion of grasshopper meal in the diets but sensory attributes appeared to be improved sightly.

Acknowledgments

The authors are grateful to Global Center for Food Systems Innovation (GCFSI) for funding the work and Egerton University, especially staff of the department of animal science who supported the data collection for this study.

Conflict of interest

The authors declare that they have no conflict of interest.

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Received 3 September 2018; Accepted 17 November 2018; Published 1 January 2019

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