Body fat mobilization during lactation in high-producing sows fed varied omega-6 to omega-3 fatty acid ratios

Abstract

The effects of reducing dietary omega (n)-6 to n-3 fatty acid (FA) ratios on body fat mobilization in lactating sows (n = 100) were investigated. Treatments consisted of a control (tallow, low polyunsaturated FA, 8:1 n-6:n-3 ratio), 3 diets with plant oil based ratios (9:1P, 5:1P, and 1:1P), and a 5:1 fish oil diet (5:1F). An epinephrine [1.6 μg kg−1 body weight (BW)] challenge was used to measure adipose tissue lipolytic activity (glycerol, NEFA, and leptin) on d 5 of lactation from a subset of sows (9:1P and 1:1P groups) fitted with jugular catheters. Lactation feed intake was greatest for control and 5:1P-fed sows (8.3 kg d−1), lowest for 1:1P-fed sows (7.4 kg d−1), and intermediate for 9:1P- and 5:1F-fed sows (7.7 kg d−1; P = 0.047). Piglet average daily gain (ADG) and estimated milk output were unaffected by diet (P > 0.10). The 1:1P-fed sows had (P < 0.10) greater backfat thickness, increased circulating leptin, and reduced feed intake, which are correlated (P < 0.10) with increased circulating glycerol and NEFA. Sows fed a plant oil based 1:1 n-6:n-3 FA ratio appeared to be in a state of negative energy balance; however, as no effects were observed on piglet ADG, these sows were able to provide the same level of nutrients to their offspring as the 9:1P fed sows.