Effects of feeding incremental levels of Spirulina platensis on feed intake and growth performance of Boschveld and Potchefstroom Koekoek chicken breeds

Spirulina is increasingly being used in feed manufacturing because of its high nutritional value, especially proteins, for humans and animals. This study examined the feed intake and growth performance of Boschveld and Potchefstroom Koekoek chicken breeds when soybean meal was substituted with incremental levels of Spirulina platensis. The experimental design was a 2 × 4 factorial with repeated measures over a 12-week period, with breed and diet as factors. The experimental unit was a cage holding 3 birds, with 3 cages allocated to each breed-diet combination, hence 36 birds per breed. The diets were: 0%, 5%, 10% and 15% using dried Spirulina platensis powder to replace soybean meal per 100 kg of feed. Chickens fed control diet consumed more (P < 0.05) feed than those fed Spirulina-containing diets. Diet affected (P < 0.0001) final weights (g) of the birds which were 1093.2, 921.6, 762.8 and 771.2 for 0%, 5%, 10% and 15% inclusion levels of Spirulina platensis, respectively. Boschveld chickens had better average daily gain compared to Potchefstroom Koekoek at week 15–16. Averaged over the 12 weeks, the control diet gave better (P < 0.0001) average daily gain (9.42 g/d) than the Spirulina-containing diets. Over the 12 weeks, the control diet had a more desirable (7.79 vs. 8.17, P = 0.01) feed conversion ratio than the Spirulina-containing diets Spirulina at a level of 5–10% can be used as a protein supplement in indigenous chicken feeds because it resulted in growth performance close to control diets.