INFLUENCE OF MICROBIAL PHYTASE ON NUTRIENT UTILIZATION IN BROILERS
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Date
2000-09
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES Mannuthy - Thrissur
Abstract
An eight week feeding trial using 180 day-old broiler chicks was
conducted to study the influence of phytase supplementation (Natuphos''^-5000)
on nutrient utilization and subsequent performance. Treatments involved a
standard broiler diet, a low available phosphorus (LAP) diet and the low available
phosphorus diet plus graded levels of phytase at the rate of 500, 750 and 1000
units / kg diet. The groups fed standard broiler diet and low available phosphorus
diets supplemented with 750 and 1000 units phytase showed significantly
(P<0.01) higher body weight and weight gain. The cumulative feed intake was
statistically comparable among the experimental diets at sixth week, whereas, at
eighth week it was significantly (P<0.05) lower in LAP diet without phytase than
that of other diets. The feed conversion ratio was significantly (P<0.01) improved
by the addition of phytase at 750 and 1000 units / kg in comparison to low
available phosphorus diet. Graded levels of phytase addition linearly improved
nitrogen retention while energy retention was significantly (P<0.01) higher in
groups fed 750 and 1000 units of phytase / kg. The addition of 750 and 1000
units of phytase / kg diet significantly (P<0.01) increased the availability of
calcium while phosphorus availability was improved by all levels of enzyme 500,
750 and 1000 units / kg. The excretion of phosphorus was significantly (P<0.01)
reduced in enzyme supplemented groups. The availability of manganese and zinc
was significantly more in enzyme supplemented groups. Tibial ash, serum
calcium and serum inorganic phosphorus were significantly (P<0.01) increased
by the addition of 750 and 1000 units of dietary phytase / kg both at sixth and
eighth week of age. The serum alkaline phosphatase level was significantly
(P<0.01) decreased in the diets supplemented with phytase. Supplementation
of phytase had no effect on per cent dressed yield and giblet yield. The per cent
R-to-C yield was significantly (P<0.05) higher in groups fed standard diet, LAP
diet and 500 units phytase supplemented diet at sixth week. Whereas at eighth
week it was significantly (P<0.05) higher in groups fed standard diet and 1000
units phytase added diet. The livability was not influenced by dietary phytase and
available phosphorus levels. The net profit per kg live weight at eighth week was
29, 94 and 85 paise higher in groups fed 500, 750 and 1000 units of phytase,
respectively in comparison to LAP diet. The results suggested that
supplementation of 750 units of phytase per kg in low available phosphorus diets
is advantageous for commercial broiler chicken production.
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