This study investigated if supplementing the diet with seaweed extracts (SWE) containing laminarin and fucoidan would promote growth performance, nutrient digestibility, and fecal consistency in newly weaned piglets during 2 growth phases as compared with ZnO. The experiment was designed as a 2 × 2 factorial with 2 levels of SWE (0 or 300 mg/kg laminarin + 240 mg/kg fucoidan) and 2 levels of ZnO [0 or added (3.1 g/kg for the starter diet and 2.5 g/kg for the transition diet)]. Dietary treatments were (i) basal diet, (ii) basal diet + ZnO, (iii) basal diet + SWE, and (iv) basal diet + ZnO + SWE. Newly weaned 6.5-kg pigs (n = 12; 4 pigs per pen) were offered supplements in a starter diet from weaning (day 0) to day 21 and in a transition diet from day 22 to day 40. There was an interaction (P = 0.005) between SWE and ZnO on G:F whereby pigs supplemented with SWE and ZnO individually had improved G:F when compared with the combination diet. There was an interaction between SWE and ZnO interaction on digestibility of DM (P < 0.01), N (P < 0.01), and NDF (P < 0.01). Pigs offered the SWE diets alone had a higher digestibility of DM, N, and NDF compared with pigs offered the basal diet. In summary, SWE induced a comparable growth performance pattern as obtained with ZnO inclusion. However, this was negated when supplements were offered in combination. Improvements in growth performance of pigs consuming SWE alone may reflect improvements in nutrient digestibility.
