Several feed additives are under investigation for improving the health and performance of broilers in this post-antibiotic era. Phytogenic feed additives like, chicory root powder (CRP)and minerals e.g. ZnSO4 has been extensively studied for this purpose in poultry. Literature indicated their positive influence on performance, mineralization of bone and muscle morphology in broiler. However, little is known regarding their utility in combination particularly with respect to their effect on performance. Therefore, present study was designed to report the individual and combined effects of CRP and ZnSO4 on performance, relative weights of viscera, histomorphometry of bones and muscles in broilers.
150 d-old broilerwerekept in environmentally controlled experimental sheds in, University of Veterinary and Animal Sciences, UVAS, Lahore. Ethical committee approved the whole procedure and proper techniques and protocols were used to handle the birds. The birds were randomly divided into six groups with five replicates (n=5) in each group. Broilerswere raised according to standard management protocol for 35 days. Group-CONT (control) received corn-based basal diet (BD), Group-2C (BD+2%CRP), Group-4C (BD+4%CRP), Group-Zn60 (ZnSO4 60mg/kg of diet), Group-2C+Zn60 (2%CRP+ZnSO4 60g/kg), Group-4C+Zn60 (4%CRP+ZnSO4 60m/kg).
During the trial, feed intake and mortality of the birds was measured on daily basis whereas body weights were taken on weekly basis. Weekly feed conversion efficiency was calculatedby dividing the feed intake by body weight. Footpads of the birds were observed for any dermatitis or inflammation. On day 35, two birds from each replicate were randomly selected and slaughtered by exsanguination. Skin and viscera of birds were removedmanually. The carcass and the relative weight of visceral organswere measured. The left and right tibia of each bird was detached as drumstick. Right tibial bone was boiled for ten minutes and then cooled down at room temperature. Afterwards flesh on the drumsticks was removed andbone were allowed to air dry at room temperature. Samples of breast (Pectoralis major) and thigh (Biceps femoris) were collected for determination of pH, WHC and histomorphometery. For histological slide preparation breast muscle sample were processed by paraffin embedding technique and stained by Hematoxylin& Eosin. Histomorphometrywas done by using software (ProgRes®2.1.1 Capture Prog Camera Control Software).One-way analysis of variance was used to analyze the data. Group differences were compared by the Duncan’s Multiple Range Test. Difference between groups was considered significant at P < 0.05.
The results revealed that at the end of the experimentgroup 4C+Zn60 had lesser (p<0.05) FI as compared to the other groups. All supplemented groups had increased (p<0.05) BW compared to that of CONT group. Moreover, a lower (p<0.05) FCR was observed in the 4C and 4C+Zn60 groups during 5th week. All the groups scored zero when observed for the footpad lesions and there was no difference in carcass weights of broilers in all the groups. All supplemented groups showed increased (p<0.05) weight of gizzard and thymus than that of the CONT group except group Zn60. Group 2C showed increased (p<0.05) weight of proventriculus compared to all of the groups. The relative weight of small intestine was increased in group 2C and 2C+Zn60. All supplemented groups showed increased (p<0.05) right tibial bone weight and length than that of the CONT group.Diaphyseal diameter, medullary canal diameter and thickness of bony wall were increased (p<0.05)in all supplemented groups except the Zn60 group. W/L index were higher (p<0.05) in all supplemented groups of CRP and ZnSO4 as compared to the CONT group. Cartilage thickness were also increased (p<0.05) in all supplemented groups as compared to the CONT group.The results revealed thatthe group 2Cand 4C showed increased (p<0.05) pH of breast and thigh muscles and increased(p<0.05) water-holding capacity and better meat quality as compared to the other groups. Histological analysis of pectoralis majormuscles revealed increased (p<0.05)muscle fascicle and fiber diameter and cross sectional area in all supplemented groups when compared to the CONT group.Results of muscle fascicles and fibers of the bicepsfemorismuscles showed increased(p<0.05) diameter as compared to the CONT group. There was no significant difference in cross section area of muscle fascicles and fibers of the bicepsfemorisof broilers.
Conclusion
Dietary supplementation of 2% and 4% CRP individually and in combination with 60mg ZnSO4 improved the performance, relative weight of gizzard, proventriculus, thymus and small intestine,meat quality and bone strength of the broilers.