Effect of feeding duration of Spirulina platensis on growth performance, haematological parameters, intestinal microbial population and carcass traits of broiler chicks

Spirulina platensis is a good candidate as an in-feed antibiotics substitute for broilers. However, its use seems impractical owing to its high price, especially when being administered throughout the whole rearing period. This study aimed to investigate the effects of feeding duration of S. platensis on growth, haematological parameters, intestinal microbial population, and carcass traits of broiler chicks. A total of 288 one-day-old broiler chicks were randomly allotted to one of four groups, including control (basal diet with 0.04% zinc bacitracin) (CONT) and birds receiving basal diet supplemented with 1% of S. platensis for the first seven days (SP-7), for 21 days (SP-21), and for 35 days (SP-35). In this study, treatments had no significant effect on the growth performance of broilers. The caecum relative weight was significantly higher in SP-35 than in CONT and SP-21 birds. The values of haemoglobin, erythrocytes, and haematocrit were significantly lower in SP-35 than in other birds. Compared with CONT, SP-35 birds had significantly lower numbers of leukocytes, lymphocytes, and a lower number of eosinophils. The numbers of coliform were significantly lower in the ileum of SP-21 than in CONT and SP-7 birds. In the caecum, coliform tended to be lower in SP-21 than in other birds. There was no significant difference in the carcass traits of broilers across the groups. In conclusion, the administration of S. platensis for the first 21 days of broilers’ life resulted in similar or even better responses than administration of S. platensis or in-feed antibiotics throughout the rearing perio