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Do varied dietary omega-6: omega: 3 ratios impact the performance, nutrient digestibility, immune status and faecal microbiota of weaner pigs
This study tested the hypothesis that altering the ratio of omega-6 (n-6) to omega-3 (n-3) fatty acids (FA) in the diet will improve growth performance, nutrient digestibility and blood parameters of weaner pigs. A total of 90 crossbred weaner pigs [(Yorkshire × Landrace) × Duroc, 28 days old] with an average body weight (BW) of 6.53 ± 0.71 kg were used in a 6-week experiment. Pigs were blocked based on BW and sex and randomly allotted to 1 of 3 dietary treatments [5 pigs per pen (2 barrows and 3 gilts); 6 pens per treatment.] Treatments consisted of plant derived n- 6 and n- 3 FAs (15:1, 10:1 and 5:1). The experimental period was divided into 3 phases: Phase 1; 28-35 days of age, Phase 2; 36- 49 days of age and Phase 3; 50-70 days of age. Supplementation of varied n-6: n-3 FA ratios in the diet of weaned pigs showed linear increases (P < 0.05) in BW and average daily gain (ADG) during phases 1 and 2. The feed: gain ratios reduced linearly (P < 0.05) during phase 1 and tended to reduce (P = 0.08) during phase 2 as the ratio of n-6: n-3 FA decreased from 15:1 to 5:1. However, the overall performance of weaners was not affected by the n-6: n-3 FA ratio. Dry matter (DM), nitrogen (N) and energy digestibility increased linearly (P < 0.05) with the reduction of n-6: n-3 FA ratio from 15:1 to 5:1 during weeks 3 and in week 6, DM digestibility showed a significant linear reduction (P < 0.05) whereas N digestibility tended to increase with decreasing n-6: n-3 FA ratio in the diet. The high density lipid/cholesterol (HDL/C) showed a significant linear increase (P < 0.05) at week 3 and a tendency to increase at week 6 but no significant effect on other serum lipids were observed. The dietary n-6: n-3 FA ratio did not have a significant effect on WBC, lymphocyte, IgG, TNFα concentrations or faecal microbial counts. In conclusion, the reduction of n-6: n-3 FA ratio from 15:1 to 5:1 in the diet did not affect the overall performance of weaning pigs. However, it showed a positive effect on the growth performance of pigs during phases 1 and 2.
AN16431 Accepted 19 September 2017
© CSIRO 2017