PS3-18. Sow Spleen as a Sustainable Immune- and Growth-promoting Additive for Young Broiler Chickens Revealed by Multi-omic Comparison and Starter Feeding.

Abstract Young broiler chickens are vulnerable to infectious morbidities and metabolic stress due to their immature immune system and rapid growth. Pig spleen, a by-product of commercial slaughterhouses, contains nutrients and immune-protective bioactives, but its use as a health- and growth-promoting additive has not been examined. This study compared spleens from sows, gilts, and barrows using metabolomic, proteomic, and biochemical analyses, and evaluated the feasibility of feeding sow spleen to young broilers by assessing growth performance, organ weight, and blood cytokines. Twenty-four freshly harvested spleen samples from sows, gilts, and barrows (n = 8/group) were ground, freeze-dried, and analyzed using liquid chromatography-mass spectrometry-based metabolomics, isotope labeling-based proteomics, and immunoglobulin analysis. Metabolomic and proteomic datasets were subjected to multivariate analysis to identify discriminative molecules, followed by one-way ANOVA to determine differences among spleen sources. In the starter feeding, 480 one-day-old male Cobb500 broilers with average BW of 41 g were allotted to 60 cages (8 birds/cage) in a randomized complete block design for five treatments (12 cages/treatment): a corn-soybean meal basal diet as the negative control (NC), a yeast cell wall product as the positive control (PC), and three diets replacing corn ingredients with 0.5%, 1.0%, or 1.5% sow spleen. The experimental diets were fed from d 0-7, followed by a common diet from d 8-21. Body weight and feed leftovers were recorded weekly to calculate ADG, ADFI, and FCR. On d 7 and 21, two birds per cage were sampled for organ weights and blood cytokines. Data were analyzed using ANOVA via the MIXED procedure of SAS with cage as the experimental unit. Omics analyses showed clear separations of sows from gilts and barrows in the multivariate models of spleen metabolome and proteome, highlighted by much more essential amino acids and innate immune proteins in sow spleen. Supplementing sow spleen linearly improved FCR from d 0 to 7 (P < 0.05), with the 1.0% inclusion group tending toward a lower FCR (P = 0.06) than NC and PC. The mortality rates in spleen-fed chickens, ranging from 1% to 3%, were numerically lower than NC (4%). Spleen supplementation had no effect on the relative weights of spleen, bursa of Fabricius, and liver on d 7 and 21, but linearly reduced serum interleukin-16 on d 7 (P < 0.05). Overall, sow spleen had a more favorable profile of nutrients and immune proteins than gilt and barrow spleens, which may contribute to the positive impacts of sow spleen supplementation on the growth performance and immune status of young chickens. These observations warrant further studies to validate its use as a sustainable additive in starter diets for young production animals.