Effects of Spirulina platensis on growth performance of weanling pigs

Three experiments were conducted to evaluate the :influence of an algae derived feed additive. Spirulina platensis (SP), on weanling pig performance. In all experiments, pigs were blocked by weight and allotted to one of four (experiments 1 and 3) or six (Experiment 2) dietary treatments. Standard diets and feeding regimens were implemented in all three experiments and SP replaced soybean meal on an equal lysine basis. Zinc oxide (3000 mg Zn kg(-1)) and medication were included in the diets for only experiments 1 and 3. In Experiment 1, a control diet or diets containing 2, 5, or 20 g SP kg(-1) were fed in a pellet form from days 0 to 14 after weaning followed by meal form from days 14 to 28 after weaning. From days 0 to 14, no differences in pig performance were observed. From days 14 to 28, a cubic (p < 0.05) response was observed for ADG and ADFI with pigs fed 20 g SP kg(-1) having greater ADG than pigs fed die control diet. In Experiment 2, dietary treatments (meal form) consisted of a control diet (no SE: fed for 6 weeks), 1 g SP kg(-1) (fed for 6 weeks) or 2 g SP kg(-1) (fed for 1, 2, 4, or 6 weeks). Pigs were switched to the control diet at the end of each SP feeding regimen. From days 0 to 14 after weaning, no differences in ADG or ADFI were observed. Pigs fed diets containing 1 or 2 g SP kg(-1) for the entire 28 days had better feed efficiency (p < 0.02) than the treatments in which SP had been removed from the diet on day 7 or 14 after weaning. However, from days 0 to 42 after weaning, no differences in ADG or ADFI were observed. In Experiment 3, dietary treatments were arranged in a 2 x 2 factorial with the main effects of feed processing (meal versus pellet) with or without 2 g SP kg(-1). From days 0 to 14 after weaning, adding SP to pelleted diets numerically tended to decrease ADG (SP x feed processing, p < 0.10), whereas adding SP to meal diets tended to improve ADG. From days 14 to 28 of days 0 to 28 after weaning, no differences in ADC, ADFI, or F/G were observed. In conclusion, the response To SP was inconsistent and occurred only with meal diets. (C) 2000 Elsevier Science B.V. All rights reserved.