University of Bonn, October 11-13, 2006
Conference on International Agricultural Research for Development
GROWTH, HAEMATOLOGY AND ORGAN HISTOPATHOLOGY IN BROILERS FED
RAW AND PROCESSED VELVET BEAN-BASED DIETS
E. A. Iyayi1, T. O. Ososanya1, V. O. Taiwo2 and O. A. Adeniji1
1Department of Animal Science, University of Ibadan, Ibadan, Nigeria, email:
2Department of Veterinary Pathology, University of Ibadan, Nigeria.
Velvet beans (Mucuna pruriens) is currently being promoted as food for man and feed for
animals in Nigeria. Its potential and implication as alternative plant protein was studied with one
hundred and eight 1-d-old Anak broiler chicks. Raw and heated Mucuna bean meals (RMBM &
HMBM, respectively) were used to replace soybean meal (SBM) and to assess the effect on
performance, histopatholpgical changes and haematology in broiler starters and finishers. Three
diets were formulated. Diet 1 was the basal diet and contained120g kg−1 SBM while diets 2 and 3
contained 120 g kg−1 HMBM and RMBM, respectively in place of SBM. Each diet had 3 groups
of 12 birds each. Feed intake, FCR and weight gain in birds on the RMBM and HMBM diets
were significantly (p < 0.05) depressed compared to birds on the SBM diet at the starter phase
but not at the finisher phase for the HMBM diet but at both phases for the RMBM diet. The
packed cell volume (PCV), haemoglobin (Hb), red blood cell count (RBC) and white blood cells
(WBC) were significantly (p < 0.05) reduced in the RMBM diets compared to the other 2 diets.
Histopathological results showed that birds on the RMBM diet showed severe and widespread
vacuolar degeneration and necrosis of the hepatocytes, interstitial congestion, tubular
degenerations and necrosis in the kidneys. The hearts in birds on the RMBM diet had
degeneration and fragmentation of their myofibrils and lymphoid depopulation in the spleen.
These results suggest the possibility of utilising Mucuna bean meal to replace soybean meal in
broiler feeding at both starter and finisher phases only when subjected to heat treatment. Thus, in
spite of its present promotion as food for man and feed for animals in the country, the bean
should be subjected to appropriate processing to overcome its depressive effects on feed intake,
growth and degenerative syndromes in organs.
In Nigeria, there is a need for readily available, high quality, alternative plant proteins that are be
inexpensive and capable of reducing production costs of meat and other animal products. It seems
that the utilization of underutilized tropical legumes will help in this regard. Such legumes may
possess as much agronomic and nutritional potential as the conventionally used ones. An
inexpensive and readily available but neglected legume is Mucuna pruriens (Velvet bean).
Mucuna pruriens is an important cover crop (or green manure crop) in many parts of the world,
especially among subsistence farmers (BUCKLES, 1995; BUCKLES et al., 1998). Like other
beans, Mucuna contains a high level of protein, vitamins and minerals making it an attractive and
important source of plant protein for feeding poultry. However, it contains some antinutritional
factors (ANFs) such as antitrypsin factors, tannins and cyanide (RAVINDRAN AND
RAVINDRAN, 1988), anticoagulants (HOUGHTON AND SKARI, 1984), analgestic, antipyretic
and anti-inflammatory factors (IAUK et al., 1993), and others (OLABORO et al., 1991). L-
dopa, a potentially neurotoxic agent occurs in large amounts in Mucuna (CAREW et al., 2003).
This study was designed to investigate the effects of dietary raw and heated Mucuna beans on the
performance, hematology and histopathology in the liver, spleen, kidney, heart, lungs and
intestines of broiler.
3 Materials and Methods
3.1 Animal housing and diets
One hundred and eight day-old broiler chicks (Anak strain) were used for this experiment. The
chicks were housed in temperature controlled brooder pens. Heated Mucuna was produced by
roasting the seeds obtained from a local feed shop with sand over fire for 40 minutes until the
shiny seed coat became dull. The roasted beans were milled using a hammer mill with a 3/16 in
screen. Three diets were formulated as shown in table 1. The control diet contained 120 g kg-1
soy bean meal (SBM), diet 2 contained 120 g kg-1 heated Mucuna bean meal (HMBM) as a
replacement for SBM, and diet 3 contained 120 g kg-1 raw Mucuna bean meal (RMBM) in place
of SBM. The chicks were allocated to the 3 experimental diets in a completely randomized design
with each treatment diet having 3 replicates of 12 birds. Feed and water were given ad libitum.
The duration of the study was eight weeks. Feed consumption and live weight measurements
were taken weekly and used to compute feed conversion ratio (FCR). Hematological parameters,
serum biochemistry and organ histopathology were also assessed. At the end of week 8, the birds
were killed, their cavity opened and the liver, spleen, kidney, heart, lungs and intestines were
quickly removed. Tissue samples from the organs were taken for hematological and pathological
Table 1: Dietary compositions of experimental starter and finisher diets
STARTER DIET FINISHER DIET
Ingredients (g kg-1) SBM HMBM RMBM SBM HMBM RMBM
Brewer’s Dried Grain
Mucuna seed meal
Fish meal (72 %)
Vitamin – mineral
*Vitamin-Mineral Premix (Agricare – Mix, Pfizer Production Plc, Lagos, Nigeria) contained per 1000g:
Vitamin A, 12,000,000 IU; Vitamin D3 2,000,000 IU; Vitamin E 7,000 IU; Vitamin B2 4,000 mg; Nicotinic
acid 15,000 mg; Calcium d-pentothenate 8,000 mg; Biotin 40 mg; Vitamin B12 10 mg; Mn 20,000 mg; Fe
50,000 mg; Zn 100,000 mg; 100,000 mg; Cu 10,000 mg; Iodine 750; Co 3000 mg.
4 Results and Discussion
Body weight gain and feed consumption of birds on the RMBM diet were reduced (P < 0.05) at
both the starter and finisher phases. Birds on the RMBM diet had poor FCR compared to those on
the SBM and HMBM diets (Table 2). The reports of HARMS et al., (1961) and OLABORO et
al., (1995) support this finding. The depression in growth observed was evident from the early
stage of the study and this could be due to the toxic effect of the anti-nutritional factors in the
bean. In the first 7 days, birds on the Mucuna diets had low feed intake but birds on the HMBM
diet, tolerated their feed more than those on the RMBM diets. During the starter phase, birds on
HMBM diet had decreased growth rate, but at the finisher phase this depressive effect on growth
did not show. The results suggest that heating reduces the growth depressing factors in Mucuna
beans. Moreover, it was observed that some of the birds on the RMBM diet had leg and neck
deformities beginning from week 4 while nervousness was noticed among the birds. These
conditions progressively caused paralysis in them by week 8 all contributing to the depressed
performance of the birds.
Table 2. Performance characteristics of broilers on diets of raw and heated Mucuna bean
STARTER DIET FINISHER DIET
SBM HMBM RMBM SBM HMBM RMBM
Wt. gain (kg)
Feed intake (kg)
Feed conversion ratio (FCR)
abc Values on the same row with different superscripts differ significantly (P<0.05)
Results of hematological values (Table 3) indicate that the Mucuna diets had significant influence
on the PCV, Hb, WBC and Neutrophil values while the Eosinophil and Monocyte values were
not affected. CHURCH et al., (1971) observed that hematological traits especially PCV and Hb
values are correlated with the nutritional status of the animal and the influence of diet on
hematological trait is very strong. The low value of PCV and Hb in birds on the RMBM diet
suggests normocytic-normochromic anemia which showed iron deficiency. This observation
agrees with the report of GRAITER et al., (1981) who noted a direct relationship between dietary
iron Hb, PCV and serum iron. The WBC value obtained on the SBM diet is fairly above the
values in the HMBM and RMBM diets which were below normal WBC count. This could mean
that the antibody formation and cell mediated immunity of birds fed the HMBM and RMBM
diets were affected. MCV values were higher than those of JAIN (1986). The MCHC values for
all the diets were of the same average and within the normal range of 30-34% reported. This
indicates adequate dietary energy for all the birds. However, the fairly low RBC value and the
high MCV value especially for birds on the RMBM diet showed hematological features of
macrocytosis or regenerative anemia.
Histopathological changes in the birds SBM diet showed that there were no histological changes
in the organs. Birds fed the HMBM diet showed mild to moderately severe vacuolar degeneration
of hepatocytes appearing slightly swollen but normal. A mild swelling of the bile ductular cells
and vacuolar degeneration were observed. Also, mild interstitial mononuclear cell filtration was
observed. There were however, no lesions observed in the heart and the brain of the birds. The
histology of the organs in birds fed RMBM diet showed severe vacuolar degeneration and
necrosis of the hepatocytes especially around the periportal region. Mild to moderate lymphocytic
periportal aggregation and kupffer cell hyperplasia were observed.
Table 3: Hematological parameters of broilers fed raw and heated Mucuna bean meal
PARAMETER SBM HMBM RMBM
RBC (x 106/ul)
WBC (x 103/ul)
Lymphocytes ((x 103/ul)
Neutrophil (x 103/ul)
Eosinophil (x 103/ul)
Monocyte (x 103/ul)
a,b,c Values on the same row with different superscripts differ significantly (P<0.05)
Furthermore, there were marked interstitial congestion, multifocal areas of glomerular and
tubular degenerations and necrosis in the kidneys. Some large tubules contain pinkish
pertinacious cast in their lumen. Also there were mild multifocal hyaline degeneration and
fragmentation of myofibrils of the heart. The brain showed focal area of neuronal degeneration,
gliosis and spongiosis especially in the grey matter while mild lymphoid depopulation was
observed in the spleen. These conditions are indicative of the degenerative effects associated with
feeding raw or poorly processed Mucuna beans.
In conclusion, results of the study showed that Mucuna has the potential for feeding broilers.
Feeding raw or heated Mucuna at a level of 120 g kg-1 diet in place of SBM caused reduced feed
intake, weight and FCR with marked effect on the histology of some internal organs and health
status of the birds. However, heating the beans prior to incorporation in the diets is effective in
ameliorating the depressive effects of the antinutrients in them on the performance of broilers at
both starter and finisher phases
BUCKLES, D.(1995).Velvet bean: a “new “plant with a history. 1995.Economic Botany
BUCKLES, D.A., EREKA, O., OSINAME, M., GALIBA, G., TIAN AND SANGINGA, N.
(1998). Cover crops in Nigeria, Sasakawa. Global 200, Cotonou, Benin.
CAREW, L. B., HARDY, D., WEIS, J., ALSTER, F., MISCHLER, S. A., GERNAT, A. AND
ZARKRZEWSKA, E. I. (2003). Heating raw Velvet beans (Mucuna pruriens)
reversessome antinutritional effects on organ growth, blood chemistry and organ
histology in growing chickens. Tropical and Sub tropical Agroecosystems, (2003):
CHURCH, D.C. AND POND, W. G. (1974). Basic animal nutrition and feeding. O & B Books,
GRAITER, P.L., GOLDSBY, J.B. AND NIEHAMAN, M. Z. (1981). Heamatoglobins and
haematocrits are they equally sensitive in detecting anaemia. Amer. J. Clin. Nutr. 34: 61 –
HARMS, R. H., SIMPSON, C.F. AND WALDROUP, P.W. (1961). Influence of feeding
various levels of velvet beans to chicks and laying hens. J. Nutrient 75: 127 – 131.
HOUGHTON, P. J. AND SKARI, K.P. (1994). The effect on blood clotting of some West
African plants used against snake bite. H. Ethnopharmacology 44: 99 – 108.
IAUK, L., GALATI, E. M., KIRJAVAINEN, S., FORESTIERI, A. M., AND TROVATO, A.
(1993). Analgestic and antipyretic effects of Mucuna pruriens. International Journal of
Pharmacognosy 31: 213 – 216.
JAIN, N. C. (1986). Veterinary clinical pathology. 4th Edition. Lea and Febieger, Philadephia.
OLABORO, G, OKOT, M. W. MUGERWA, J. S. LATSHAWA, J.D. (1991). Growth-
depressing factors in velvet beans fed to broilers chicks. East African Agricultural and
Forestry Journal. Uganda 57(2): 103 – 110.
RAVINDRAN, V. AND RAVINDRAN, G. (1988).Nutritional and antinutritional characteristics
of mucuna bean seeds. Journal of the Science of Food and Agriculture 46: 71–79.