Some Physiological Factors Affecting The Productive Efficienct In Chicken:

.mohamed Zaki Abdalla Nofal

This study was carried out at the Poultry Research Farm Belongingto Department of Animal Production, Faculty of Agriculture, Zngn1,igUniversity~.Benha branch.It was aimed to determine the possibility of further improvement ofthe laying :performance and egg quality of the two breeds of chicken Hisexi and Shaver, applying different levels of calcium and vitamin D3.Two hybrids of chicken were chosen: Hisex as a white hybrid and Shaver as a brown hybrid. An equal number of 540 day old female Hisex and Shaver breed hatched on Jlily 1995, were used in this study.Chicks from each hybrid were divided into 9 experimental groups of30 chicks each. Birds were fed a standard growing rations, but differed in the level of dietary calcium (0.8, 1.2 and 1~.60/0)and vitamin D (800, 1200and 1600 I.C.U). At sexual maturity pullets were fed standard layer ration,but differed in dietary calcium level (3.5, 4.5 and 5.50/0) per each level ofvitamin 0 previously mentioned.I Body weight was recorded at hatch, Ith week age, at sexual maturity and at the end of experimental period. Feed consumption was daily recorded. Feed conversion was calculated for each treatment as kg ration/kg e~g produced. Age at sexual maturity, egg production rate, egg weight and mass were estimated throughout the experimental period whichlasted for 8 periods of 21 day each and considered as traits of eggproduction performance.Absolute and relative weights of egg components, shell thickness and shell weight unit per surface area were estimated as traits of eggquality. Plasma calcium, inorganic phosphbrus and alkaline phosphatase ,were also detennined. At sexual maturity, at 500/0, the peak of eggi production and at the end of the experimental period calcium absorptionrate for each intestinal part was detennined in vitro as total calciumabsorption, .absorption per cm intestinal length and per gram dry matter of intestinal weight.Resuits obtained could be summarized , as follows : 1. Pullets of Shaver breed had the highest live body weight averages along the growing and laying period. 2. Hisex pullets matured earlier (162.5 days). It had tighter body weight at sexual maturity (989.2 g) while pullets of Shaver hybrid were the latest to reach sexual maturity (167.3 days) having the heaviest body weight (1127.3 .g). 3. Dietary calcium level showed highly significant effect on both age and body weight at sexual maturity, while it showed insignificant effect on egg weight. Providing pullets with 4.5% calcium in the diets delayedsexual maturity for 4.3 days it also decreased the egg weight by 0.27 g, Iwhile 5.50/0 calcium level delayed sexual maturity for 7.1 days anddecreased egg weight by 0.96 g when compared with diets containing3.5% calcium level .4. Pullet’s’ breed, dietary calcium and’ vitamin D3 level had highly significant effects on egg production .. Rate of egg production washigher for Hisex pullets (62.230/0/hen/day), for pullets received 3.5 i calcium I, (69.70 %lhen/day) and for pullets fed 800 I.U vitamin Dr level (65.15°/olhen/day).5. Pullet’s hybrid and dietary calcium level had no significant effect on eggweight, however dietary vitamin 03 level had significant effect-on eggweight : 6. The higher egg mass was obtained from pullets of Hisex hybrid. Pullets hybrid, dietary calcium and vitamin 03levels had significant effect on egg mass. Providing pul1ets with 3.50/0 calcium had higher egg massfollowed by 4.5% then by 5.5% calcium, respectively. 7. Pullets of Hisex breed had better feed conversion (2.83 kg ration /kg egg) than those of Shaver breed (3.00 kg ration/kg eggs). Dietarycalcium level showed insignificant effect on feed conversion whiledietary vitamin OJ level had significant effect on this trait.8. Dietary vitamin 03 level was only the factor that had insignificant effecton feed consumption. Shaver pullets significantly increased the averageof feed consumption (103.6 g/hen/day) when compared with Hisexpullets (99.4 g1henlday). Dietary calcium level had highly significanteffect on feed consumption, pullets fed 3.50/0 calcium level had thehighest average of feed consumption (10?5 g/hen/day) when comparedwith the other two levels.9. Egg of Shaver pullets were characterized by their higher albumen weight percent (61.670/0) and lower yolk and shell proportional weights(25.930/0 and 9.81%, respectively). However, eggs of Hisex hybridwere characterized by lower albumen weight percent (61.10%) andhigher yolk and shell proportional weights’ (26.320/0 and 10.37%,respectively). Diets containing 3.5% calcium and 800 LV had bettereffect on albumen weight percent than I did other diets applied. Dietcontaining 4.5% calcium and 1200 LV. vitamin D3 had the better effecton shell weight percent. 10. Highly significant variation was found ’in shell thickness due to thepullet’s hybrid. Hisex pullets laid eggs with thicker shell (OA03 mrn)than pullets of Shaver hybrid (0.358 mm). Dietary calcium level hadhighly significant effect on shell thickness. Providing dietary calcium ata level of 3.5% increased shell thickness (0.387 nun) when comparedwith the other two levels of dietary calcium. While dietary vitamin D3level had insignificant effect on shell thickness. 11. Plasma calcium content was significantly affected with dietary calcium level, pullet’s fed 5.50/0 calcium had higher level of plasma calcium (23.9 roWIOO ml). On the other hand,no significant variation in this< I trait were observed due to pullet’ s hybrid or dietary vitamin D3 level.Plasma inorganic phosphorus content was significantly affected withpullet’s hybrid, Hisex pullets had the highest level of plasma inorganicphosphorus. Dietary calcium and vitamin D3 levels had highly i ’t significant effect on plasma inorganic phosphorus. On the other hand dietary vitamin 03 level had highly significantly effect on plasma alkaline phosphatase,’ while pullet’s hybrid and dietary calcium level I had insignificant effect on plasma alkaline phosphatase.12. At sexual maturity only, pullet’s hybrid showed significant effect oncalcium absorption per ern length of small intestine. However, at the endof the experimental period, pullet’s hybrid showed highly significantIi effect on calcium absorption per gram dry matter. Dietary calcium levelshowed ,highly significant effect on calcium absorption per em lengthand pet gram dry matter at sexual’ maturity, while it showedinsignificant effect on these traits at the end of the experimental period.Dietary vitamin D3 level showed significant effect on total calciumabsorption, absorption per cm length and per gram dry matter at sexualmaturity, 13. Variation in all parameters of calcium absorption rate were observed to I be significant due to the small intestinal part. Ileum had always the higher averages of both total calcium absorption, calciumabsorption/em length or per gram dry matter.