Effects of unconventional diets and unconventional low-protein diets on reproductive performance, placental nutrient transport, and fecal microorganisms of multiparous sows during gestation

The objective of this experiment was to investigate the effects of unconventional ingredients (wheat, broken rice, rapeseed meal, rice bran meal, and fermented distiller grains) in sow diets on sow reproductive performance, placental nutrient transport function, and fecal microbiota. Thirty multiparous sows with similar parity and backfat thickness were randomly assigned to 3 groups: corn-soybean meal diet (CG), unconventional diet (DY), and unconventional low-protein diet (DYL). The DYL group had 2% lower crude protein than CG and DY. Sows were fed experimental diets during gestation and a corn-soybean meal diet during lactation. Results showed that unconventional ingredients did not negatively affect sow reproductive performance. Compared to the CG treatment, the DY treatment showed a trend of increasing the weaned litter weight (P = 0.061). Compared to the DY treatment, the DYL treatment showed a trend of reducing the number of mummified fetuses (P = 0.066) and increasing the number of weaned piglets (P = 0.096). Additionally, unconventional ingredients enhanced placental nutrient transport gene expression (P < 0.05) and fecal butyric acid content (P < 0.05). Compared to the CG treatment, the DY treatment reduced the apparent digestibility of organic matter, energy, crude protein, and crude fiber but increased the digestibility of crude fat (P < 0.05). In terms of inflammatory factors, the DYL treatment significantly decreased the serum IL-6 content in sows at 90 and 110 d of gestation (P < 0.05). In terms of fecal microbiota, the DY treatment significantly increased the Observed_features and Chao1 indices (P < 0.05), indicating an improvement in fecal microbiota diversity, compared to the CG treatment. At the phylum level, the DYL treatment increased the relative abundance of Proteobacteria. At the genus level, compared to the CG treatment, the DY treatment significantly increased the relative abundance of Anaerovibrio and Ruminococcus, while reducing the relative abundance of Treponema. Additionally, compared to the DY treatment, the DYL treatment significantly increased the relative abundance of Alloprevotella, Prevotella, and Parabacteroides. In summary, replacing corn and soybean meal with unconventional ingredients and reducing protein levels during gestation did not adversely affect sow reproductive performance. During periods of significant price fluctuations in corn and soybean meal, incorporating unconventional ingredients into feed formulations can serve as an alternative solution.