Digestibility and Nutritional Value of Microalga Tetraselmis sp. for Weaner Piglets

Twenty-four male piglets were randomly assigned to four dietary treatments, with increasing <i>Tetraselmis</i> sp. incorporation levels (0%, 5%, 10%, and 15%). Following a 4-day adaptation period to metabolic cages, the animals were used in a 2-week digestibility trial and slaughtered for digestive tract measurements and sampling. The apparent total tract digestibility (ATTD), N balance, small intestine digesta viscosity and histomorphology, and hindgut digesta volatile fatty acid (VFA) profile were determined. Polynomial contrasts were employed to examine linear and quadratic effects of <i>Tetraselmis</i> sp. dietary incorporation. The ATTD of most macronutrients and N retention efficiencies decreased linearly (<i>p</i> < 0.05) with <i>Tetraselmis</i> sp. dietary inclusion. The ileum villi height increased linearly (<i>p</i> < 0.001) and the hindgut VFA concentration increased linearly (<i>p</i> < 0.05) with dietary <i>Tetraselmis</i> sp. inclusion. The ATTD values estimated for <i>Tetraselmis</i> sp. biomass using the regression method were 68.3% ± 3.86 for dry matter (DM), 66.1% ± 5.11 for N, and 61.3% ± 4.28 for gross energy. The values calculated for digestible and metabolizable energy (MJ/kg DM) and digestible crude protein (% DM) for <i>Tetraselmis</i> sp. were 9.0, 8.8, and 18.3, respectively. <i>Tetraselmis</i> sp. biomass had lower ATTD values when compared to protein sources commonly used in swine nutrition.