Reduction in dietary crude protein and addition of fiber could mitigate the incidence and severity of post-weaning diarrhea, a common gastrointestinal condition in newly weaned pigs. Therefore, 360 weanling pigs, initially 5.0 ± 0.10 kg, were used to evaluate the effects of crude protein (CP) level and fiber source on growth performance and fecal microbial communities. At weaning, pigs were randomly assigned to pens and allotted to 1 of 8 dietary treatments in a 2 × 4 factorial with main effects of CP (21 or 18%) and fiber source (none, coarse wheat bran, oat hulls, or cellulose). There were 5 pigs per pen and 9 pens per treatment. Experimental diets were formulated in two dietary phases from d 0 to 10 and 10 to 24, with a common post-treatment diet fed from 24 to 45. The 21% CP diets contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2. By using a maximum SID Lys:digestible CP ratio of 6.35%, the 18% CP diets contained 1.25% SID Lys in both phases. Diets containing a fiber source were formulated to the level of insoluble fiber provided by 4% coarse wheat bran, resulting in the addition of 1.85% oat hulls and 1.55% cellulose. No fiber source × CP level interactions (P > 0.05) were observed. Decreasing CP (and subsequently SID lysine) decreased (P = 0.05) ADG and G:F during the experimental period. From d 0 to 45, ADG decreased (P = 0.05) for pigs fed 18% CP diets compared to pigs fed 21% CP. No effect of fiber source was observed for growth performance. Fecal DM on d 17 increased (P < 0.001) for pigs fed 18% CP diets compared to pigs fed 21% CP diets. Pigs fed diets with added cellulose had increased (P < 0.05) fecal dry matter during the experimental period compared to pigs fed no fiber source or wheat bran. Bacterial community structure was investigated by sequencing the V4 region of the 16S rRNA gene. Analysis indicated a significant difference between CP content at d 24 (P = 0.023) using a Weighted UniFrac distance matrix. Further investigation identified five differential Amplicon Sequence Variants associated with CP content at d 24. In conclusion, reducing crude protein (and subsequently SID Lys) decreased growth performance but increased fecal dry matter content. The source of dietary fiber in nursery diets had no impact on growth performance; but pigs fed added cellulose had increased fecal DM compared with other treatments. Microbial analysis identified differential taxa associated with CP content.

中文翻译：

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纤维来源和粗蛋白水平对保育猪生产性能和粪便微生物群落的影响

减少日粮粗蛋白和添加纤维可以减轻断奶后腹泻的发生率和严重程度，这是刚断奶仔猪常见的胃肠道疾病。因此，使用 360 头初始体重 5.0 ± 0.10 kg 的断奶仔猪来评估粗蛋白 (CP) 水平和纤维来源对生长性能和粪便微生物群落的影响。断奶时，猪被随机分配到围栏中，并分配到 2 × 4 因子中的 8 种日粮处理中的一种，主要影响 CP（21 或 18%）和纤维来源（无、粗麦麸、燕麦壳或纤维素） . 每个栏有 5 头猪，每个处理有 9 个栏。实验日粮被配制成从第 0 天到第 10 天和第 10 天到第 24 天的两个日粮阶段，使用从 24 天到 45 天喂养的普通后处理日粮。21% CP 日粮包含 1. 第 1 阶段为 40% 标准化回肠可消化 (SID) Lys，第 2 阶段为 1.35% SID Lys。通过使用 6.35% 的最大 SID Lys：可消化 CP 比率，18% CP 日粮在两个阶段均含有 1.25% SID Lys。含有纤维来源的日粮被配制成 4% 粗麦麸提供的不溶性纤维水平，导致添加 1.85% 的燕麦壳和 1.55% 的纤维素。没有观察到纤维来源×CP水平相互作用(P＞0.05)。在实验期间，降低 CP（以及随后的 SID 赖氨酸）降低 (P = 0.05) ADG 和 G:F。从第 0 天到第 45 天，与饲喂 21% CP 的猪相比，饲喂 18% CP 日粮的猪的平均增重下降 (P = 0.05)。没有观察到纤维来源对生长性能的影响。与饲喂 21% CP 日粮的猪相比，饲喂 18% CP 日粮的猪在第 17 天的粪便干物质增加 (P < 0.001)。与没有喂食纤维来源或麦麸的猪相比，喂食添加了纤维素的猪在实验期间增加了 (P < 0.05) 粪便干物质。通过对 16S rRNA 基因的 V4 区域进行测序来研究细菌群落结构。使用加权 UniFrac 距离矩阵分析表明 CP 含量在 d 24 (P = 0.023) 之间存在显着差异。进一步调查确定了 5 个与第 24 天的 CP 含量相关的差异扩增子序列变体。总之，减少粗蛋白（以及随后的 SID Lys）会降低生长性能，但会增加粪便干物质含量。保育日粮中膳食纤维的来源对生长性能没有影响；但与其他处理相比，饲喂添加纤维素的猪粪便干物质增加。