Effects of dietary omega-3 polyunsaturated fatty acids on growth and immune response of weanling pigs

Abstract Text: The recognition that omega-3 polyunsaturated fatty acids (n-3 PUFA) possess potent anti-inflammatory properties in human models has prompted studies investigating their efficacy for animal growth and immunity.  The objective of this study was to examine the effect of feeding an n-3 PUFA-enriched diet on growth and immune response of weanling piglets.  Newly weaned pigs (averaging 27 ± 2 d of age and 8.1 ± 0.7 kg of BW) were assigned randomly to receive a control (3% vegetable oil, n = 20) or n-3 PUFA-supplemented (Omega, n = 20) diet for 28 days after weaning.  Diets were formulated to be isocaloric (3.3 Mcal / kg of diet) and isolysinic (14 g Lys / kg of diet).  A diet × gender × week interaction was detected (P < 0.04) for body weight.  Female pigs consuming the n-3 PUFA-enriched diet were lighter (P < 0.01) at wk 4 post-weaning than their counterparts fed the vegetable oil-supplemented diet. Newly weaned pigs gained more weight (P < 0.01), consumed more feed (P < 0.01) and had better G : F (P < 0.01) between d 14 and 28 than between d 0 and 14 post-weaning.  Peripheral IGF-1 concentration decreased (P < 0.01) between d 0 (87.2 ± 17.0 ng/mL) and 14 (68.3 ± 21.1 ng/mL) after weaning and then increased again by d 28 (155.2 ± 20.9 ng/mL) post-weaning.  In piglets consuming the vegetable oil-enriched diet, plasma TNF- α concentration increased (P < 0.04) from 37.6 ± 14.5 to 102.9 ± 16.6 pg/mL between d 0 and 14 post-weaning and remained high through d 28 (99.0 ± 17.2 pg/mL) post-weaning.  The TNF-α increase detected in the piglets fed vegetable oil was not observed in the piglets fed n-3 PUFA (d 0 = 33.0 ± 17.2 pg/mL; d 14 = 29.1 ± 21.7 pg/mL; d 28 = 36.7 ± 21.4 pg/mL).  With the exception of blood platelets and eosinophil cells, dietary n-3 PUFA had minimal effects on hematological characteristics.   Fecal consistency scores improved (P < 0.01) with increasing weeks after weaning, but were similar between the two dietary treatments.  Results indicate that weaning induces considerable immune stress on piglets and that this stress can be mitigated by dietary supplementation of n-3 PUFA.

Keywords: n-3-PUFA, growth, immunity, pig