Palm fatty acid distillate (PFAD) is a by-product of palm oil (P) refining. Its use in chicken diets is a way to reduce the cost of feed and the environmental impact. Its low unsaturated:saturated fatty acid ratio (UFA:SFA) and its high free fatty acid (FFA) level could be partially counteracted by its blending with soybean oil (S). The objective was to assess the effect of replacing S with different levels of PFAD on lipid-class content and fatty acid (FA) digestibility along the intestinal tract and in the excreta of 11 and 35-day-old broiler chickens. Five experimental diets were prepared by supplementing a basal diet with S (S6), PFAD (PA6), two blends of them (S4-PA2 and S2-PA4), or P (P6) at 6%. Replacing S with PFAD did not affect performance parameters (p > 0.05) but negatively affected feed AME, FA digestibility, and FFA intestinal content (p < 0.05), especially in starter chicks. Including PFAD delayed total FA (TFA) absorption (p < 0.05) at 11 days, but at 35 days it did not affect the TFA absorption rate. The use of PFAD blended with S, when FFA ≤ 30% and UFA:SFA ≥ 2.6, led to adequate energy utilization in broiler grower-finisher diets.

Zinc oxide (ZnO) has been used at pharmacological levels to promote gut health and growth performance in the critical postweaning (PW) phase of piglets. The pharmacological use of ZnO in piglet diets has been banned in Europe and other countries due to antimicrobial resistance and environmental concerns. Therefore, understanding its mode of action, including its molecular mechanisms, is crucial for developing effective and sustainable alternatives. We investigated the mechanisms by which dietary supplementation with 3,000 mg/kg ZnO supports gut health and improves growth performance of piglets during the first 14 days PW. During the 2 weeks of trial (0–14 d PW), ZnO fed piglets had higher average daily gain (165 vs. 123 g/d; p < 0.01), and tended to have increased average daily feed intake (204 vs. 181 g/d; p < 0.1) and improved gain-to-feed ratio (0.669 vs. 0.774; p < 0.05) compared to control piglets. Feces from piglets in the ZnO group were also more consistent during the 2 weeks of trial (p < 0.01). At day 14 PW, ZnO piglets had lower calprotectin concentrations in serum (p < 0.01). Dietary ZnO downregulated several genes, involved in immune, oxidative and inflammatory responses, in jejunal (GPX2, REG3G, IL-8, IL-6, IL-22, and TGFβ1) and ileal (REG3G, IL-17A, IL-1β, and TLR2) mucosa (p < 0.05). It also downregulated the expression of the zinc transporter SLC39A4, that is associated with zinc homeostasis, in both tissues. Notably, PPARGC1A, which promotes energy production and lipid metabolism through fatty acid oxidation, was upregulated by ZnO in ileum. In conclusion, the current results suggest that high dietary levels of ZnO reduce the expression of inflammatory cytokines, the oxidative enzyme GPX2, pathogen recognition proteins, and zinc transporters while promoting the expression of PPARGC1A gene related with energy metabolism in the intestine. Therefore, ZnO can facilitate a smoother weaning transition to reduce weaning related gut health disturbances, ultimately contributing to gut homeostasis and improved performance.

This study aimed to evaluate the replacement of palm oil (P) with increasing levels of soybean acid oil (SA), a by-product of soybean oil (S) refining, on lipid class content and fatty acid (FA) digestibility in the intestine and excreta of chickens at 11 and 35 days (d). Five experimental diets were obtained by supplementing a basal diet with 6% of P (P6), 6% of SA (SA6), 4% of P + 2% SA (P4-SA2), 2% of P + 4% of SA (P2-SA4) and 6% of S (S6). A total of 480 one-d-old female broiler chickens (Ross 308) were housed in metabolic cages (6 cages/treatment, with 16 birds/cage). Replacing P with SA improved fat absorption at 11 and 35 d (p < 0.05), but not feed AME values and saturated FA (SFA) digestibility at 11 d. As age increased, the absorption of SFA and free fatty acids (FFA) improved, and the contribution of the upper ileum to FA absorption increased (p < 0.05). At 35 d, SA6 (56% FFA) and P2-SA4 (40% FFA, 2.6 unsaturated-to-saturated FA ratio) could replace S6 without impairing fat utilization. The replacement of P with SA represents a suitable strategy to use this by-product.

The viability of raising pigs from weaning to slaughter with inorganic phosphorus (iP)-free diets using a hybrid 6-phytase was tested in two trials. Three experimental diets were formulated: T1, a control diet with monocalcium phosphate (MCP); T2, a diet without MCP + phytase (P and Ca phytase matrix formulation); and T3, a diet without MCP + phytase (P, Ca + extra nutrients in a phytase matrix formulation). Rapeseed and sunflower meal were used in addition to soybean meal as protein sources, in order to increase the phytate-P content. Performance was monitored from weaning to slaughter, and bones were sampled at the slaughterhouse to test for bone mineralization. In the second trial, gait scores were also assessed at 75, 110, and 134 days. Weight gain was not significantly affected by treatment in either trial. However, in Trial 1, males receiving T2 had a reduced overall feed efficiency than males receiving T1, whereas in Trial 2, a reduced overall feed efficiency was observed for T3 relative to T2 (p < 0.05), probably due to the extra nutrient reduction. No differences in bone mineralization or gait score were observed. In conclusion, it is possible to raise pigs without iP by using phytase in feeds containing phytate-P. This may contribute to more sustainable pig production with reduced P excretion and lower usage of rock phosphate, a limited resource.