This experiment was conducted to evaluate the effects of a second iron injection for suckling pigs fed diets with different dietary iron levels in the nursery period on growth performance, hematological parameters, serum and liver trace mineral content, fecal score, microbiome, and metabolites. A total of 70 newborn pigs from 7 litters were assigned to either one or two iron injections within litter and received the first i.m. iron injection (200 mg) at 2-3 d of age. Pigs assigned to the second injection treatment received an additional iron injection 5 d after the first injection. At weaning (d 27-30 of age), pigs within iron injection treatments were divided into 2 nursery diet treatments for a 27-d growth period. Treatments were: 1) no additional iron injection + nursery diets with 100 ppm iron (NC), 2) second i.m. iron injection (200 mg) + NC diets, 3) no additional iron injection + nursery diets with 200 ppm iron (PC), and 4) second i.m. iron injection (200 mg) + PC diets. The second iron injection increased liver iron content at weaning (P = 0.08, tendency), and serum iron, hemoglobin, and hematocrit levels until d 13 postweaning (P < 0.05). In the nursery period, pigs receiving the second iron injection had a greater final body weight (P = 0.08, tendency), overall growth rate (P = 0.08, tendency) and feed intake (P < 0.05), and lower fecal score (P < 0.05) indicating firmer feces compared to those receiving one iron injection. There was no major effect of dietary iron level or interaction with the iron injection treatment in any measurements except that the pigs fed the PC diets had greater hemoglobin and hematocrit levels (P < 0.05) at d 27 postweaning and a lower fecal score (P = 0.08, tendency) in the late nursery period than those fed the NC diets. The second iron injection reduced fecal bacterial alpha-diversity based on Faith’s phylogenetic diversity at weaning (P < 0.05), while the second iron injection and dietary iron levels resulted in dissimilarity in the fecal bacterial community based on Unweighted Unifrac analysis (P < 0.05; at weaning by iron injection and d 27 postweaning by dietary iron level). In conclusion, the second iron injection for suckling pigs improved postweaning growth performance and hemoglobin levels and affected the fecal microbiome, whereas an additional 100 ppm of dietary iron supplementation increased hemoglobin levels and altered the fecal microbiome in the late nursery period but did not affect postweaning growth.

中文翻译：

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第二次铁注射对饲喂不同日粮铁水平仔猪生长性能、血液学参数和粪便微生物组的影响


本试验旨在评价保育期饲喂不同日粮铁水平日粮的乳猪第二次注射铁对生长性能、血液学参数、血清和肝脏微量矿物质含量、粪便评分、微生物组和代谢物的影响。将 7 窝的 70 头新生猪分配到窝内注射 1 次或 2 次铁剂，并在 2-3 日龄时接受第一次 i.m. 铁注射 （200 mg）。分配到第二次注射处理的猪在第一次注射后 5 天再接受一次铁注射。断奶时（27-30 日龄），将铁注射处理的猪分为 2 个保育日粮处理，生长期为 27 天。处理是：1） 不额外注射铁 + 含 100 ppm 铁 （NC） 的育苗日粮，2） 第二次 im 铁注射 （200 mg） + NC 日粮，3） 不额外注射铁 + 含 200 ppm 铁 （PC） 的育苗日粮，以及 4） 第二次 im 铁注射 （200 mg） + PC 日粮。第二次铁注射增加了断奶时肝脏铁含量 （P = 0.08，趋势），以及血清铁、血红蛋白和血细胞比容水平，直到断奶后第 13 天 （P < 0.05）。在保育期，接受第二次铁注射的猪的最终体重（P = 0.08，趋势）、总生长速率（P = 0.08，趋势）和采食量（P < 0.05）和粪便评分较低（P < 0.05），表明与接受一次铁注射的猪相比，粪便更坚硬。除了断奶后第 27 天饲喂 PC 日粮的猪血红蛋白和血细胞比容水平较高 （P < 0.05），保育期后期粪便评分较低 （P = 0.08，趋势） 外，日粮铁水平或与铁注射处理的交互作用在任何测量中均无重大影响。 根据断奶时 Faith 的系统发育多样性，第二次铁注射降低了粪便细菌 α 多样性 （P < 0.05），而根据未加权 Unifrac 分析，第二次铁注射和日粮铁水平导致粪便细菌群落的差异（P < 0.05;断奶时通过铁注射和断奶后 d 27 按日粮铁水平）。总之，乳猪第二次注射铁剂改善了断奶后生长性能和血红蛋白水平，并影响了粪便微生物组，而额外补充 100 ppm 的日粮铁剂增加了血红蛋白水平，并改变了保育期后期的粪便微生物组，但不影响断奶后生长。