The increase in human population in Nigeria over the last decades has
greatly influenced the demand for food products of animal origin hence
the livestock producers at large are having difficulties in meeting the
demand for animal products by the ever-growing population. The Food and
Agricultural Organization (FAO, 1985) recommended a minimum of 56g of
animal protein intake per person per day. Many Nigerians cannot meet this
requirement due to high cost of animal products (Fasuyi, 2005).
An effective and quick approach for balancing the demand and supply of
animal products in Nigeria and other developing countries is through the
expansion of the livestock industry especially through the use of animals
with short generation intervals. Rabbit is one of such animal species.
It is highly prolific with short generation intervals, early maturity
and rapid growth rate (Cheeke, 1980). Baymen (1984) reported that rabbit
meat rank highest in protein and lowest in fat content (cholesterol) and
calories compared to beef, chicken, mutton and pork.
A major constraint of the livestock industry in meeting consumer demand
for more meat, milk, egg and other livestock products is dependent to
a major extent on the availability of regular supplies of appropriate,
cost effective and safe animal feeds and as a result, animal feeds have
become an increasingly critical component of the integrated food chain
(FAO, 2004). Further more, among all the nutrients required for effective
performance of monogastric and Pseudo-ruminant animals, energy has remained
the most abundant nutrient to supply in a balanced diet constituting between
45-60% of finished feeds (Nestel, 1975; Machin, 1992). Maize has also
remained the major source of energy supply in livestock diets. In several
developed and developing countries, the highest proportions of maize produced
are used for animal feed, hence maize has been and continues to be an
indispensable cereal grain in the diets of monogastic and pseudo-ruminant
animals and it typically form between 50-60% of such diets. The normal
maize variety used in livestock diets has two significant flaws; like
all cereals, firstly, it is low in protein (9-10%) and secondly, it does
not provide the essential amino acids; (lysine and tryptophan) in sufficient
quantities for the nutritional needs of farm animals, thus as far as protein
quality is concerned, the normal maize variety has poor protein quality
(Okai et al., 2005; Vasal, 2006). Thus, livestock diets based on
normal maize are supplemented with protein — rich feed ingredients
such as soyabean meal, fishmeal and synthetic lysine to compensate for
the deficient lysine.
However, improving maize varieties to possess an improved balance of
essential amino acids can reduce the dietary inclusions of protein - rich
ingredients such as fishmeal and synthetic lysine and thereby provide
savings on the cost of feed and production, thus making animal products
more affordable. “Opaque-2 variety is an example of such improved
maize with high protein content and the lysine and tryptophan levels are
better than those of the normal maize. Animals (chicken and pigs) fed
this variety of maize (Opaque-2) have significantly performed better than
their counterparts fed on normal maize (Asche et al., 1985; Sullivan
et al., 1989; Okai et al., 2005;).
However, the development of high lysine mutant maize “Opaque -2-mutant
through intensive breeding have succeeded in producing Quality protein
maize (QPM) which is richer in lysine, tryptophan and other amino-acids
than the existing maize lines. QPM contain twice the amount of essential
amino acids than in normal maize (Showemimo et al., 2005; Babu,
2005) and it yield 10% more grain than the traditional varieties of maize
(Surinder and Evangelina, 1999). Okai et al. (2005) reported that
a particular variety of QPM known as Obatamppa in Ghana contained 0.36%
lysine in contrast to the 0.23% in normal maize and that except for methionine;
the levels of six other indispensable amino acids were also high. Although
these levels of lysine are lower than that in the conventional protein
sources such as soyabean (4.00%) and Blood meal (7.00%), but the fact
that maize constitutes about 50-60% of the diets of rabbits and monogastric
animals makes the contribution of lysine in maize to be of great importance.
Supplementation of QPM in the diets of rabbits and monogastric animals
is therefore very important as QPM could be seen to substitute for high
protein but rather costly sources like soyabeans, fishmeal and Blood meal
(Vasal, 2006). QPM is relatively cheap and an excellent source of lysine
and other essential amino acids such as tryptophan since the quantity
of the maize is very high in the ration. Thus most of the benefits of
using QPM as an animal feed are likely to be through economic savings,
in addition to being superior in protein quality and higher in feed efficiency
The Objectives of the Study are to:
||Determine the proximate composition of both local maize
and Quality Protein Maize.
||Determine the effects of QPM on the performance and carcass characteristics
of weaner rabbits.
||Determine the economic implication of feeding rabbits with QPM as
replacement for the normal maize.
Materials and Methods
Experimental location: The research was carried out at the livestock
unit of the Teaching and Research unit of the Department of Animal Science,
Ahmadu Bello University, Zaria, Kaduna State, Nigeria.
Laboratory analysis: The laboratory studies involved the determination
of proximate composition of the local maize, QPM and formulated diets
according to A.O.A.C (1990) procedures.
||Proximate analysis of quality protein maize and normal
Biological study: Growth trials were conducted using 36 weaner
rabbits in a completely randomized experimental design to evaluate the
percent replacement of normal maize with QPM in rabbit diets using groundnut
cake as protein source. There were six treatments with six rabbits per
treatment. The rabbits were individually caged. Diets were formulated
to meet the NRC (1995) nutrient requirements for rabbits. The experiment
lasted for eight weeks. Table 2 shows the composition
of diets for the study.
The rations involved a percent replacement of normal maize with QPM as
||Maize — Groundnut cake base diet (100% Normal
||Maize — Groundnut cake based diet (75% Normal Maize + 25%
||Maize — Groundnut cake based diet (50% Normal Maize + 50%
||Maize — Groundnut cake based diet (25% Normal Maize + 75%
||Maize — Groundnut cake based diet (100% QPM)
||Maize — Groundnut cake based diet (100%Normal Maize + Synthetic
Management of experimental animals and data collection: The rabbits
were fed for two days with the feed under test to remove residues of previously
fed feeds from their digestive tract. The rabbits were dewormed before
the experiment commenced, and proper sanitary conditions were maintained
to avoid disease outbreak. The rabbits were weighed at the start of the
experiment; the initial weights was recorded and subsequently weighed
on a weekly basis. Feed intake, weight gain, feed efficiency, water consumption,
mortality rate, cost per kg feed (N) and cost per kg weight gain (N) were
computed. The rabbits were weighed at the end of the experiment to get
the final live weight.
Carcass evaluation: At the end of the study, three rabbits per
treatment were randomly selected, weighed, slaughtered and eviscerated
for carcass evaluation. The rabbits were skinned, the head, tail, skin
and legs were cut off and weighed, each animal was cut open, the alimentary
canal, heart, liver, lungs, kidneys and spleen were removed and weighed
individually. The weight of the warm carcass devoid of internal organs
||Composition of the experimental Diets
|*A Vitamin mineral premix provides per kg of diet: Vitamin
A, 13.340 i.u; D3, 2680 i.u; Vitamin E, 10 i.u; Vitamin
K, 2.68 i.u; Calcium pantothenate, 10.68mg, Vit B12 0.022mg;
Folic acid, 0.668mg; choline chloride 400mg; chlorotetracycline, 26-28mg;
Manganese, 133.34mg; Iron, 66.68mg; Zinc, 53.34mg; copper, 3.2mg;
Iodine, 1.86mg; Cobalt, 0.268mg, selenium, 0.108mg. *QPM: Quality
Protein Maize. * ME: Metabolizable energy. *GNC: Groundnut cake, *i.u:
The skinned carcass was dissected into retail cuts of loin, shoulder
and thigh, which were then weighed individually. The weight of each of
these organs was expressed as a percentage of the live weight.
Data analysis: Data collected were subjected to analysis of variance
as described by Steel and Torrie (1980). Significance difference was determined
by applying the Duncan’s Multiple Range Test (Duncan, 1955) across
The proximate composition of quality protein maize and normal maize
variety: The proximate composition of Quality Protein Maize and Normal
Maize are presented in Table 1. The average dry matter
content is 96.84%, crude protein 8.25%, crude fiber 3.33%, ether extract
15.86%, total ash 2.95%, NFE 66.45% for QPM and dry matter content of
92.70 %, crude protein 7.42 %, crude fiber 4.8 %, ether extract 14.00%
and total ash 1.76%, NFE 64.72% for normal maize.
Effects of graded levels of quality protein maize on weaner rabbits:
The effects of the treatments on the performance of weaner rabbits are
presented in Table 3. There was no significant difference
(P > 0.05) in initial weight (g), final weight (g), daily feed intake
(g), daily weight gain (g), feed efficiency, daily water consumption (ml),
mortality rate and feed cost/kg weight gain (#) across the treatments.
There was significant difference (P < 0.001) in feed cost/kg feed
(#/kg) across the treatments.
Carcass analysis: The result of carcass yield is shown in Table
Live-weight was significantly (P < 0.05) lowest at 50% level of supplementation
and highest at 100% level. However, there was no significant difference
(P > 0.05) in live-weight between rabbits offered the diet at 0, 25,
50, 75% and control. Slaughter weight followed similar pattern as live-weight.
There was no significant difference (P > 0.05) in carcass weight across
Length of small intestine was significantly (P < 0.05) lowest in control
and 100% level of supplementation and highest at 0% level of supplementation.
However, there was no significant difference (P > 0.05) in the length
of small intestine in the rabbits offered the diets at 25, 50 and 75%
levels of supplementation.
The length of large intestine was significantly (P < 0.05) lowest
at 0 and 25% level of supplementa-tions and highest in the control diet.
However, there was no significant difference (P > 0.05) in the length
of large intestine at 50, 75 and 100 percent levels of supplementation.
There was no significant difference (P > 0.05) in the dressing percentage
across the treatments.
There was no significant difference (P > 0.05) in the heart, shoulder,
loin, thigh, lungs, kidneys, head, skin, spleen, weight of full stomach,
weight of empty stomach, weight of full small intestine, weight of empty
small intestine, weight of full large intestine and weight of empty large
||Performance of weaner rabbits fed graded levels of Quality
Protein Maize (QPM) based-diets
|a, b, c, d, e, f, means with different superscripts
within the same row differ significantly. NS: Not Significant (P >
0.05). LOS: Level of Significance. SEM: Standard Error of the Mean.
There was significant difference (P < 0.05) in the liver, legs and
tail but there was no specific trend established.
At 0% level of supplementation, the liver is significantly (P < 0.05)
highest and lowest at 25%, 75% levels of supplementation and control diet.
However, there was no significant difference (P > 0.05) at 50 and 100%
At 50% level of supplementation, the percent weight of legs is significantly
highest and lowest at 100% level. However, there was no significant difference
(P > 0.05) at 0, 75% levels of supplementation and control diet.
The tail was significantly (P < 0.05) highest in rabbits fed control
diet and lowest at 100% level of supplementation. However, there was no
significant difference (P > 0.05) at 0, 25, 50 and 75% levels of supplementation.
There were slight variations among most of the nutrients in both the
normal maize and Quality Protein Maize. The protein content in QPM is
not far different from those of normal maize. This agrees with the report
of Prasanna et al. (2001), although some studies showed higher
levels for QPM (Rostango et al. 1990). Differences in comparison
with other literature may be due to varietal, soil and climatic conditions
(Soh et al., 1994)
The crude protein value of 8.25% for Quality protein maize and 7.42%
for normal maize, obtained in this study agrees with the reports of other
workers (Prasanna et al., 2001). 3.33% and 4.80% for QPM and regular
maize were obtained respectively as values of crude fiber.
The results of the performance of rabbits showed that there was no significant
effect of diets on any of the performance parameters measured.
Feed intake was numerically highest in the 100% and lowest in 0% levels
of inclusion of QPM. Daily feed intake was observed to increase with increase
in the dietary levels of QPM. However, higher levels of feeding QPM resulted
in higher total feed intake.
There was no significant difference (P > 0.05) among the treatments
for weight gain, although rabbits fed 75 and 100% QPM diets had a numerical
faster rate of gain than those fed the control diet. The highest weight
gain was observed at 100% level of inclusion. Body weight gains increase
with increased level of QPM in the diet. This can be explained by increase
in nutrient intake and utilization. This can be seen in the trend in feed
to gain ratio, which improved with higher levels of QPM in the diets.
This agrees with the reports of Asche et al. (1985); Sullivan et
al. (1989); Lopez-Pereira (1992); Okai et al. (2005), that
animals (chicken and pigs) fed this variety of maize (QPM) gained more
weight than their counterparts fed on normal maize. The decline in weight
gain at 50% level of inclusion can be attributed to faster rate of passage
of the feed through the gastro-intestinal tract (GIT) and therefore less
retention time for digestion and utilization.
Level of supplementation of QPM had no significant difference (P >
0.05) in feed efficiency among all the treatments. The efficiency with
which feed was converted to gain showed a trend indicating that the higher
the level of QPM fed the better the fed efficiency. A lower fed conversion
ratio implies more feed being retained in the animal and less waste into
the environment (Gebhart, 2001). Feed to gain ratios was better on the
QPM-based diets, indicating that lower amounts of the QPM diets were consumed
and converted to meat. This suggests that QPM is superior in feed efficiency
than normal maize variety. Lopez-Pereira (1992) reported similar efficiency
of feed utilization for chicken and pigs.
Level of feeding QPM had no significant (P > 0.05) effect on the quantity
of water consumed, but the higher the level of inclusion of QPM the higher
the quantity of water consumed, even though the quantity consumed was
not significantly different from that of rabbits on control diet and normal
maize variety. The highest water consumption was observed in the control
In this experiment, differences among treatments were not significant
(P > 0.05) for feed cost per unit of weight gain, but values were numerically
lower for QPM diets. The highest feed cost per unit of weight gain was
observed in the control diet, indicating that the rabbits in this treatment
ate more to gain less weight. The results suggest therefore that QPM based-diets
reduce cost of production though not significantly.
||Carcass characteristics of weaner rabbits fed graded
levels of Quality Protein Maize expressed as percentage of live-weight
a, b, c means with different superscripts within
the same row differ significantly.
NS: Not significant (P > 0.05). *: Significant (P < 0.05).
LOS: Level of Significance. SEM: Standard Error of the Mean.
FS: Full Stomach. ES: Empty Stomach. FSI: Full Small Intestine.
ESI: Empty Small Intestine. FLI: Full Large Intestine.
ELI: Empty Large Intestine. Wt: Weight.
Level of feeding QPM had no significant (P > 0,05) effect on carcass
traits of the weaner rabbits. Pre-slaughter weight increased as level
of feeding QPM increased except at 50% level of inclusion. However, at
higher levels of feeding QPM (75 and 100%), there were no significant
differences (P > 0.05) in pre-slaughter weight. Increased level of
feeding resulted in increased intake and nutrient utilization. Rabbits
fed 100% level of QPM have the highest live-weight and were significantly
(P < 0.05) higher than those fed 50% level of QPM, but no significant
difference (P > 0.05) was observed in pre -slaughter weight in rabbits
fed 0, 25, 75, 100% and control diet.
There were significant difference (P < 0.05) in slaughter weight,
but it follows similar trend as pre - slaughter weight, indicating that
level of feeding did not affect the quantity of drainable blood.
There were no significant (P > 0.05) variation in carcass weight of
rabbit fed QPM diet and those fed on 0% and control diets. 100% QPM inclusion
had the highest carcass weight, though not significantly different (P
> 0.05) from the other treatments.
There were no significant (P > 0.05) variations in the dressing percentage
of rabbits fed with or without QPM.
Level of feeding had significant (P < 0.05) effect on the size of
the liver, length of the intestines (small and large), legs and tails.
The size of the liver was highest in the rabbits fed 0% level of QPM and
lowest in rabbits fed 25, 75% QPM and control diet. However, there were
no significant difference (P > 0.05) in rabbits fed 25, 50, 75, 100%
and control diet.
There were no significant difference (P > 0.05) in the size of the
heart, shoulder, loin, thigh, lungs, kidneys, head, skin, spleen, weight
of stomach (full and empty), and weight of intestines (full and empty).
Conclusion: The results obtained from this study indicated that:
I)Rabbits could be raised on QPM-based diets without lysine supplementation.
II)QPM-based diets improved feed: gain ratio and feed cost per kg weight
gain, indicating a reduction in cost of production.