Standardized ileal digestible linoleic acid requirement of modern lactating sows: A dose–response study

Linoleic acid (LA) and α-linolenic acid are essential fatty acids which cannot be synthesized in the body and must be provided through the diet. Insufficient or excess dietary intake of essential fatty acids has been shown to be associated with various disorders and diseases, such as oxidative stress, tissue damage, and mitochondrial dysfunction.

Objective: Therefore, the objective of the present work was to determine the standardized ileal digestible (SID) linoleic acid requirement of lactating sows using dose–response estimation methods.

Methods: A total of 100 sows were randomly assigned to five treatment groups with 20 replicates per group. The five diets contained 1.47%, 1.91%, 2.32%, 2.74%, or 3.15% SID LA. The experimental period lasted from day 107 of gestation until weaning.

Results: Reproductive performance of sows was not affected by dietary SID LA levels; however, piglet weaning weight linearly increased with increasing SID LA levels. Litter weight on day 14 increased with SID LA until reaching a plateau at 2.36% of SID LA, whereas the plateau of litter weight on day 21 was observed at 2.15% of SID LA. The contents of immunoglobulin A in colostrum and immunoglobulin M in milk showed a trend towards parabolic pattern with SID LA levels, peaking at 2.41% of SID LA. Additionally, plasma tumor necrosis factor-α levels in 7-day-old piglets followed the same parabolic pattern. The content of immunoglobulin G on day 21 of lactation in sows linearly increased with higher SID LA levels. The level of total antioxidant capacity of piglets on day 21 showed an inverted U-shaped relationship with SID LA levels, peaking at 2.23% of SID LA. The glutathione peroxidase activity of piglets on day 7 increased linearly with the increase of SID LA and reached a plateau at 2.07% of SID LA.

Conclusion: Using broken line and quadratic regression model, the standardized ileal digestible linoleic acid requirement for lactating sows ranged from 2.07% to 2.43% to achieve optimal litter weight, milk immunoglobulin, and antioxidant capacity of sows and piglets.