MVSc

A 3 x 3 factorial experiment was carried out at the Department of
Poultry Science, Kerala Agricultural University during the period from
February to July 2002 to establish the optimum requirements of calcium (Ca)
and available phosphorus (AP) in the diets for indigenous layer ducks under
cage system of rearing.
The Kuttanad varieties of indigenous ducklings of Kerala were
maintained on deep litter system of rearing until 18 weeks of age at the
University poultry farm, Mannuthy. From this flock, Ninety (90) female
ducks were housed in 45 California type cages at the rate of two ducks per
cage and they were weighed individually at 20 weeks of age. The dimension
of each cage was 60 x 45 x 40 cm and the floor area of 1350 cm2 per duck
was provided in the cage. The experimental diets were fed from 21 to 40
weeks of age and the observations were recorded in five periods of 28 days
each. Nine experimental diets containing three levels of Ca viz., 3.0, 3.5 and
4.0 per cent with three levels of AP viz., 0.40, 0.50 and 0.60 per cent were
formulated and were fed to nine treatments consisting of five replicates of two
ducks per cage in each treatment in a 3x3 factorial design.
The mean body weight of ducks at 20 weeks of age was uniform III
all groups ranging from 1400±9.11 to 1465±53.24 g with an overall
mean of 1431±9.96 g. The Ca and AP levels did not influence significantly
the 40th week body weight, which ranged from 1473±18.10 to 1579±58.28 g
with an overall mean of 1544± 13.7 6g. The age at first egg in the flock with
3.0, 3.5 and 4.0 per cent Ca levels were 154, 158 and 148 days respectively
and with AP levels 0.4,0.5 and 0.6 per cent the same were 161, 154 and 148
days respectively.

The period wise mean duck housed number (DHN) from 25-40 weeks
of age (18.1eggs) was significantly higher with ducks fed 4.0 per cent Ca
(P<0.05). The interaction effect was significant (P<0.05) for the dietary
combination of 4.0 per cent Ca and 0.6 per cent AP with 20.2 eggs. The
cumulative egg number (EN) of 75.7 eggs from 21 to 40 weeks of age was
also higher with the Ca level 4.0 per cent and the 71.9 per cent production
with diet T9 was superior by interaction effect (P<0.05). The duck housed
per cent (DHP) production from 25 to 40 weeks of age averaged 64.6±1.92
per cent with 4.0 per cent Ca level.
The Ca and AP levels in the diet did not influence the mean daily feed
consumption, feed conversion ratio (FCR), egg mass and shell thickness. The
overall mean daily feed consumption was 137.2±1.49 g per duck. The FCR
per dozen eggs was 2.8±0.078 and that per kg egg was 3.9±0.099 for the
period from 25 to 40 weeks of age. The mean egg weight (EW) and per cent
shell were highly significant and the EW of 60.1±0.575 g averaged with
3.0 per cent Ca and 0.5 per cent AP level as well were high (P interaction effect with the above combination was also significant (P The 9. 7±0. 081 per cent shell recorded with 0.5 per cent AP was significantly
lower in comparison with other AP levels (P<0.05).
At 40 weeks of age, the overall mean serum Ca was 15.42±0.35 mg/dl
and serum P was 3.18±0.081 mg/dl. The mean serum inorganic P value of
2.92±0.164. mg/dl recorded with dietary Ca level 4.0 per cent was
significantly lower than that of 3.5 per cent Ca level (P<0.05). The tibia ash
(62.34±0.512 per cent) was significantly higher with 0.6 per cent dietary AP
level (P<0.05) and the tibia ash Ca with 4.0 per cent dietary Ca level was
significantly higher and the interaction effect with 0.6 per cent AP level was
also significant. With this AP level, the tibia P was reduced significantly, but




the interaction showed that the tibia P was high with diet T9. The liveability
was excellent in ducks reared in cages (100 per cent) and there was no
mortality during the period from 21 to 40 weeks of age.
In the present study, the production traits used for evaluating the Ca
and AP requirements of caged layer ducks were EN, EW, egg mass, feed
consumption and FCR. The study revealed that 4.0 per cent Ca in the diet was
superior over other Ca levels in the diet. The dietary Ca and AP levels did not
influence the mean daily feed consumption and feed conversion ratios
significantly. On the other hand, dietary AP levels influenced the mean EW,
per cent shell, tibia ash weight and tibia ash Ca and P. Though the mean EW
of 60.1±O.566 g recorded with 0.5 per cent AP was significantly higher,
the significant interaction on egg number with the 0.6 per cent AP with
4.0 per cent Ca was found superior. Therefore it will be logical to set the
requirements of AP at 0.6 per cent level.
Thus, the overall results of the present study revealed that the
4.0 per cent Ca and 0.6 per cent AP levels with 18 per cent Crude Protein
and 2650 Kcal ME/kg was optimum for egg production in indigenous layer
ducks under cage system of rearing.