Effects of spirulina (Arthrospira platensis) as feed additive of steers consuming high energy diets: growth performance, carcass characteristics, morbidity, and nutrient digestion

Abstract

Two trials were performed in order to evaluate the effects of spirulina platensis (SP) supplemented (0, 0.5, and 1.0% of diet DM) in high-energy diet on nutrient digestion and growth-performance of feedlot cattle. The dose of each treatment was top dressed and mixed directly with the basal diet at time of feeding. In Trial 1, six cannulated Holstein steers (281±2 kg) were used in a replicated 3×3 Latin square experiment. Supplemental SP did not affect ruminal and total tract nutrient digestion. Ruminal microbial efficiency (quadratic component, P=0.06), nitrogen efficiency (linear component, P=0.10) and ruminal pH (linear, P=0.06) tended to decrease with SP supplementation, without further effects on ruminal VFA or estimated methane production. In Trial 2, 108 medium-frame crossbred steers (182±1 kg) were used in a 211-d study to evaluate growth performance. SP dietary supplementation did not affect feed intake, but linearly tended (P=0.09) to decrease weight gain, gain efficiency, and estimated dietary net energy. Supplemental SP also tended (P=0.08) to linearly increase steer morbidity. Effects of SP supplementation on carcass traits were not significant, but longissimus muscle area tended to linearly decrease (P=0.06).It is concluded that low level (≤1%) of Spirulina platensis supplementation (powder form) has minimal effects on characteristic of digestion and may negatively impact on growth performance, feed efficiency, and morbidity of feedlot cattle fed a high energy finishing diet.