INFLUENCE OF CHROMIUM SOURCES ON PERFORMANCE OF GIMMIZAH CHICKENS FED LOW METABOLIZABLE ENERGY AND CRUDE PROTEIN DIETS

This study was done to investigate the influence of chromium sources (organic; Cr-yeast and inorganic; Crcl₃) on the performance of Gimmizah chickens fed low metabolizable energy (LME) or low metabolizable energy and crude protein (LMECP) diets.  A total number of 280 (245 hens + 35 cocks) of Gimmizah chickens (aged 28-weeks) were individually weighed and randomly divided into seven treatment groups, with five replicates for each (7 hens+1cock) and housed (open system) in 35 floor pens during the experimental period (28 - 44 weeks of age).  The first group was fed the basal diet and served as a control (2750 kcal ME/kg diet + 17.0 %CP). The second one was fed low metabolizable energy diet (LME, 2600 kcal ME/kg diet + 17.0 % CP). The third group was fed low metabolizable energy and crude protein diet (LMECP, 2600 kcal ME/kg diet and 15.5 %CP).While the fourth and fifth groups were fed LME diet supplemented with 1200 µg/kg diet of organic or inorganic chromium (Cr), respectively. Whereas the sixth and seventh groups were fed LMECP diet supplemented with 1200 µg/kg diet of organic or inorganic Cr, respectively.  The groups fed LME supplemented with both sources of Cr significantly improved egg production, egg mass, feed conversion ratio, shell thickness, Haugh units and SWUSA compared with the groups fed LME and LMECP diets and similarly equal with the control group. Layers fed LME supplemented with organic Cr significantly increased fertility, hatchability percent of both total and fertile eggs and chick weights compared with the groups fed LME or LMECP diets and were statistically equal with the control group. The blood concentration of total lipids, triglycerides, Ca, MDA, TAC, GSH and insulin were significantly improved for groups fed LME or LMECP supplemented with both sources of Cr compared with the other groups. Blood concentration of cholesterol, heterophil, phagocytic activity and phagocytic index for the group fed LME diet supplemented with organic Cr were significantly improved compared with the groups fed LME and LMECP diets.  Economical efficiency value indicated that the group fed LME diet supplied with organic Cr recorded the highest economical efficiency (1.13) and relative economical efficiency (113.6 %) compared with the control group. In conclusion, addition both sources of Cr for LME diet improved and recovery the layer performance to the control group. However, addition of organic Cr for LME diet recorded the best economical efficiency compared with the other experimental groups.