Exploitation of Maximum Production Potential of Spent Layers through Induced Molt by Varying Nutritional Regimes

Abstract

Induced molt is used to bring spent layers in another egg production cycle and helps to supply the eggs to the consumer at cheaper price, eventually extending a helping hand in reducing the protein shortage in the country. Post-fast feeding of birds with varying nutritional regimes had variable effects on their egg production, blood biochemistry, hormonal profiles and endocrine glands performance. Keeping in view the above-mentioned problems there is a need to formulate a feed which can be used during post molt period. A total of 420 Single Comb White leghorn hens were induced to molt and fed rations containing different levels of crude protein and metabolized energy (CP-10; ME-3400 TO CP-18; ME-2900) during post molt period of 21 days. Different parameters i.e. egg production, egg quality, meat quality, organoleptic evaluation of meat, immunohistochemistry of pituitary glands and immune status were determined after induced molt during second production cycle. Body weight of molted hens did not change, while the dressing percentage was significantly high in F7 and low in F5 and F6 fed groups. Body weight as well as dress weight of birds was significantly high at peak production stage. The amount of fat recovered from birds fed different formulated feed was significantly high in all groups expected F2. Liver and Heart weight did not change in different feeding groups. However, liver, heart and kidney weight were significantly high at Peak production stages. Thyroid weight was significantly high in F2 and lowest in F6, while brain weight was significantly high in F6 and low in birds fed F5 and F7 diet. Thyroid as well as brain weight was significantly high at peak production level. Gastrointestinal weight was significantly low at 5% production stage and it did increase but the differences were not significant at peak production level and then decrease at the end of production. Egg production of molted hens fed different formulated feed have indicated that birds in all groups attained 5% production in 2 weeks expect in F1 where it took 6 weeks. Peak production did vary significantly and the timer recoded was from 17 weeks, (F1 and F7), 24 weeks (F5), 13 weeks (F6), 12 weeks (F4), 10 weeks (F2) and 7 weeks (F3). After 30 weeks of egg production, most of the feeding groups were still producing 60 to 78% of eggs. Overall F7 gave the highest production (75%) while 61% was recorded F4 and 62% in F1 group. Feed consumption/bird/week was significantly high in F5 group as compared to other groups. FC/bird/week was significantly high at peak production stage. FC/kg of egg mass was found to be increase significantly high in F7 and low in F2, F3, F5, F6 AND F7 groups. FC/dozen of eggs as well as FC/kg egg mass did increase significantly at the peak production stage. Egg weight of molted birds was significantly higher in all groups except in F4. At peak production stage egg weight was significantly high in all groups. Number of eggs/bird/week was significantly high in F5 and lowest in F1 and F3 fed groups. Overall egg number/bird/week did increase from 5% to 50% and at peak production level. White diameter was significantly high in F3 and low in F4 while yolk diameter was significantly high in F2 and low in F4 and F5 groups. Yolk as well as white diameter did decreased at peak production stage. Haugh unit was significantly high in F1 and F4 and overall it did increase significantly at production stages. Egg shell thickness did not change in all groups except in F1 where it was significantly low at 5% production and highest at the end of production stage. Egg shell weight did decrease significantly at peak production stage. Plasma glucose and cholesterol concentration did not differ significantly while total proteins was significantly high in F5 and low in F7. Plasma albumin concentration was high in F3 and F6 and significantly low in F1 group. Total proteins, albumin and globulin did increase significantly at peak production. Plasma globulin, triglyceride, AST, ALT, T3, T4 and cortisol did not differ between F1 to F7 groups. At peak production, total proteins, albumin, globulin and triglyceride were significantly high while ALT, T3 and cortisol were significantly low. Number of somatotrophs did not change during different stages of production as well as in different feeding groups. Moisture contents of muscles were significantly higher in F7 group as compared to F1, F2 and F3 for thigh muscle and F2 for breast muscle. Thigh and breast muscle proteins, fat did not change between groups. Thigh ash contents were significantly high in all groups except F1, while breast ash was significantly high in F2 and F7 and lowest in F1 group. Muscles, proteins, fat and ash contents were significantly high at peak production stage, while moisture contents tends to decrease and then increase significantly at the end of production stage. Muscle color, flavor, taste and tenderness was not affected by different experimental ration, however, breast taste score was significantly high in F4 and juiciness in F7 groups. Immunological status presented in geometric mean was significantly high in F4 and F7 for New-Castle disease (NCD) and for F7 for egg drop syndrome (EDS) while both were lowest in F1 group. At peak production these values were significantly high as compared to at 5% and at the end of production stage.