Growth Performance of Nursery Pigs Fed Microalgae Carbohydrate Product

The objectives of this study were to evaluate the effects of a carbohydrate rich, partially de-oiled microalgae extract (MAE) in nursery pig diets on growth performance and health status. A total of 320 pigs (initial BW = 6.3 ± 2.1 kg) were used in a 42-d trial. Treatments included a control corn-soybean meal diet, and control diet with MAE inclusion as to act as a potential prebiotic (1%) or as an alternative feed ingredient (5, 10, and 20%). Diets were formulated for a 3 phase feeding program to meet or exceed NRC nutrient requirements for nursery pigs containing 3,400 kcal/kg of ME. Pigs were stratified by weaning weight into 12 blocks in a complete block design, with sex distributed evenly among blocks. Pens of pigs (5 pigs/pen) were assigned randomly within block to 1 of 5 treatments. Pig weight and feed disappearance was recorded weekly. The number of pigs that showed signs of illness and received individual doses of antibiotics were recorded. Pig mortality was calculated on a treatment basis. Data were analyzed using a mixed model with pen (block × treatment) as the random effect, and period, treatment, and period x treatment as fixed effects. Linear and quadratic orthogonal polynomial contrasts were used to evaluate differences between diets with varying levels of MAE. Over 6 wk, ADFI tended (P = 0.08) to increase quadratically (Con:731, 1%:766, 5%:754, 10%:761, 20%:718 g) and ADG increased (P = 0.03) quadratically (Con:496, 1%:531, 5%:517, 10%:529, 20%:500 g) with the inclusion of MAE. The 1% and 10% treatment groups showed the greatest overall ADFI and ADG. A total of 18 out of 320 pigs were treated with antibiotics, with the control (8/60) and 20% MAE (4/60) representing the largest number of treated pigs. The largest number of dead pigs came from pigs fed the control diet (3/60) and the 5% MAE (3/60). Overall, pigs fed the 1% and 10% MAE diets had the lowest percentage of antibiotic treatments and mortality. We observed that diets with 10% and 20% inclusion levels did not flow properly in the feeders, thus high inclusion of the MAE product may increase labor. In conclusion, an inclusion level of 1% of MAE provided the greatest improvement in ADG, ADFI, and indicators of health of nursery pigs, also indicating a potential role for MAE as a prebiotic for nursery pigs.

Key words: microalgae, growth performance, nursery pigs