OPTIMUM ENERGY AND PROTEIN REQUIREMENTS OF BROILER RABBITS
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Date
1995
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR
Abstract
A detailed investigation involving two series of growth studies spread over a
period of 24 weeks in Soviet Chinchilla and Cross Bred rabbits was carried out to
establish the optimum energy and protein requirements for growth and to ascertain the
optimum age for economic slaughter. One hundred and eight weanling Soviet
Chinchilla and 108 weanling cross bred (SC X NZW) rabbits formed the experimental
subjects. Rabbits of each breed were divided into nine identical groups and maintained
factorially on three levels of crude protein (CP) viz., 12, 16 and 20 per cent and
digestible energy viz., 2000, 2500 and 3000 kcal/kg for over a period of 168 days
involving metabolism and slaughter studies during 8th, 16th and 24th week of
experiment and production traits along with associated characters were studied and the
salient results are presented.
Rabbits maintained on different energy protein combinations showed significant
difference in growth rate (P <0.01). Both dietary energy and crude protein were found
to influence the average daily gain. The highest rate of gain was achieved in animals
maintained on ration containing comparatively higher DE and CP while lowest rate of
gain was noticed in animals maintained on low energy, low protein diet. On further
scrutiny of the data, an appreciably better and identical gro\A4h response was observed
in animals maintained on ration containing 3000 kcal DE/kg with 16 per cent CP and
ration containing 2500 kcal DE/kg with 20 per cent CP in both pure bred and cross bred
rabbits. It is also noticed that for maximum growth rate a ration containing 2500 kcal.
DE/kg need be sufficient as further increase in DE have not evinced any better response on ADG, which supports the view that for optimum biological response, a ration containing 2500 kcal DE/kg is sufficient for both pure bred and cross bred rabbits. As between the periods it was observed that the animals attained maximum
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ADG during the first 56 days of experiment and there after ADG gradually declines irrespective of the level of CP or DE in the ration.
Both dietary energy and crude protein significantly influenced (P <0.01) the feed conversion efficiency of animals. Highest efficiency of feed conversion was noticed in rabbits maintained on Ration D containing 2500 kcal DE/kg and 20 per cent CP the values being 9.27 in SC and 8.85 in CB rabbits and further increase in DE from 2500 kcal/kg to the extent of 3000 kcal/kg did not contribute better feed efficiency. Data on feed efficiency further revealed that maximum efficiency was observed during the first eight weeks after weaning and there after there is a linear reduction in feed efficiency
as the age advances, in all the nine dietary treatments.
With regard to cost of production the maximum biological and economical efficiency could be observed in animals maintained on ration containing 2500 kcal DE/kg with 20 per cent CP and when the cost of production was evaluated in between the periods viz., 0 to 56 days, 56 to 112 days and 112 to 168 days, the cost efficiency
is seen maximum during 0 to 56 days of experiment.
Dry matter intake on percentage of body weight was found decreasing on increasing the dietary energy level. Haematological values were with in the normal range and were not significantly influenced by the dietary energy and protein levels. Digestibility of nutrients and percentage retention of nitrogen, calcium and phosphorus were significantly influenced by the dietary treatments with an increasing trend on increasing the dietary energy and protein level. From the metabolism studies carried out during 8th, 16th and 24th week of experiment, the percentage retention of nitrogen, calcium and phosphorus were found reduced on advancing the age of animals.
Slaughter studies conducted at 8th, 16th and 24th week of experiment reveaJed that dressing percentage is directly proportional to the pre-slaughter weight of the
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animals, ligher dressing percentage is recorded in animals having higher body weight
and vice-vrsa. Carcass yield were higher at 16th and 24th week of experiment than
that at eiglh week of experiment.
Rerding the chemical composition of meat, the moisture and crude protein
content otiry matter basis decreased on advancement of age, without any significant
influence dietary treatments, while the fat content progressively increased with
increase ige and dietary energy content. Total ash content (dry basis) decreased
with increiin age and dietary DE levels. An increase in liver protein percentage was
observed i increase in dietary protein level. As the dietary energy level increased,
liver fat cent showed an increasing trend. Iodine number of the abdominal fat was
not foundifluenced by the dietary energy-protein levels and age of the animal.
Saponifican value also was not influenced by the dietary CP and age of the animal.
Abnce of appreciable quantities of abdominal fat during the 8th week
indicates 6t for the production of lean meat, animals can be slaughtered during 8th
week aften/eaning.
Evaiation of the data on slaughter studies indicate that broiler rabbits when
slaughtere( during 8 to 16 weeks after weaning yielded maximum profit, the profit
accrued isseen inversely proportional to the increase in age of the animals with
maximum pofit obtained from slaughter during 8th week after weaning.
Frori a critical evaluation of the data gathered during the present investigation it
can be reaonably concluded that broiler rabbits require a dietary level of 20 per cent crude protei and 2500 kcal DE/kg feed for evincing optimum growth and slaughtering rabbits durig 8th week after weaning is ideal for maximum profit.
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