dc.description.abstract |
Three experiments were run to study the effects of dietary microbial
xylam 500 (xylanase + amylase) enzyme (Experiment 1), phytase (Nutrase P)
enzyme (Experiment 2) and their combinations (Experiment 3) on performance
and carcass characteristics of broiler chicks fed on diet containing 10% wheat
bran. The experimental design used in each experiment was completed
randomized design (CRD). Two control diets were formulated in each
experiment, (A) negative control diet (without wheat bran or enzymes) and (B)
positive control diet (with 10% wheat bran). In experiment one, two levels of
microbial xylam, 500 and 750 g/ton were added to the positive control diet. In
experiment two, two levels of microbial phytase, 1000 and 1500 g/ton were
added to the positive control diet. In each experiment, 120 seven day-old
unsexed Hubbard broiler chicks were used. The chicks in each experiment were
allotted randomly in 4 treatment groups ×5 replicates, each of 6 chicks. In
experiment three, 4 dietary combinations of xylam and phytase enzymes, (500
and 1000 g/ton); (750 and 1000 g/ton); (500 and 1500 g/ton) and (750 and 1000
g/ton) respectively were added to the positive control diet, using 180 seven day-
old unsexed Hubbard broiler chicks, allotted randomly to 6 treatment groups× 5
replicates, each of 6 chicks. All chicks in each experiment were formulated to
be isonitrogenous (22.8%) and isocaloric (3100 kcal/kg) according to the
recommended dietary requirements for broilers (NRC, 1994). Experimental
parameters covered performance, slaughter and carcass data and economic
appraised.
The results showed that the addition of microbial xylam and phytase
enzymes, individually or in combinations to the diet containing wheat bran
improved significantly (P<0.05) the body weight gain, feed intake and feed
conversion ratio values of the broiler chicks at different stages of the growth.
XIII
No significant differences were observed between wheat bran diets
supplemented with the two enzymes, separately or in combinations and the
negative control diet in body weight gain, feed intake and feed conversion ratio
values of broiler chicks. The mortality rate was not significantly influenced by
the dietary treatments.
The results indicated that there were no significant differences among all
treatment groups in the percentages of carcass dressing, internal organs (liver,
heart and gizzard) commercial cuts (thigh, drumstick and breast) and their
percent of separable meat; meat chemical composition (moisture, protein, fat
and ash) and subjective meat quality parameters (tenderness, juciness, flavour
and colour) of the broiler chicks.
Economically appraised values were profitability ratio (1.18) of group C.
(500g xylam/ton) was the highest of the test groups. Profitability ratio (1.22) of
the test group C (1000g phytase/ton) was the highest of the test groups.
Profitability ratio (1.06) of the test group E (500 and 1500/g xylam and phytase
combinations) respectively was the highest of the tests groups. |
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