Abecia Leticia, Balcells Joaquím, Fondevila Manuel, Belenguer Alvaro, Holtrop Grietje, Lobley Gerald E
Departamento de Producción Animal y Ciencia de los Alimentos, Universidad de Zaragoza, 50013, Spain.
Br J Nutr. 2008 Nov;100(5):977-83. doi: 10.1017/S0007114508957986. Epub 2008 Mar 12.
The contribution of microbial amino acids through caecotrophy to tissue protein metabolism was investigated in lactating does. Attempts were made to vary microbial supply through a dietary antibiotic, Zn bacitracin, and to vary tissue demand through manipulation of litter size. Three groups of eight New Zealand does were fed different experimental diets from day 28 of pregnancy to day 26 of lactation. The control group received the basal diet formulated to meet requirements with grass hay, wheat, soybean meal and barley grain. The second (no antibiotic) group and the third (bacitracin; BAC) group ingested the basal diet supplemented with ammonium sulfate (5 g/kg), initially unlabelled (day 1 to day 8) then labelled with 15N (day 9 to day 30), while the BAC diet was also supplemented throughout with antibiotic (Zn bacitracin; 100 mg/kg). From just after birth each group of does was subdivided into two groups, each of four females, with the litter size either five (LS5) or nine (LS9) pups. The 15N enrichment in liver, milk and caecal bacteria amino acids was determined by GC-combustion-isotope ratio MS. All amino acids in bacterial protein were enriched with the (15 NH 4)2SO4 treatment, with lysine 15N enrichment significantly greater in caecal bacteria (0.23 (SE 0.0063) atom % excess (ape)) than in liver (0.04 (SE 0.0004) ape) or milk protein (0.05 (SE 0.0018) ape), confirming the double origin (bacterial and dietary) of tissue lysine. The contribution of microbes to tissue lysine was 0.23 (SE 0.006) when milk protein was used as reference.
在泌乳母羊中研究了通过粪食摄入的微生物氨基酸对组织蛋白质代谢的贡献。通过日粮抗生素杆菌肽锌来改变微生物供给，并通过调整窝仔数来改变组织需求。从怀孕第28天到泌乳第26天，将三组八只新西兰母羊分别饲喂不同的实验日粮。对照组接受以禾本科干草、小麦、豆粕和大麦粒配制的基础日粮，以满足营养需求。第二组（无抗生素组）和第三组（杆菌肽组；BAC组）摄入添加硫酸铵（5 g/kg）的基础日粮，最初未标记（第1天至第8天），然后用15N标记（第9天至第30天），而BAC组日粮在整个实验期间还添加了抗生素（杆菌肽锌；100 mg/kg）。从出生后不久开始，每组母羊再分为两组，每组四只母羊，窝仔数分别为五只（LS5）或九只（LS9）幼崽。通过气相色谱 - 燃烧 - 同位素比率质谱法测定肝脏、乳汁和盲肠细菌氨基酸中的15N富集情况。在（15NH4）2SO4处理下，细菌蛋白质中的所有氨基酸均有富集，盲肠细菌中赖氨酸的15N富集显著高于肝脏（0.23（标准误0.0063）原子% 过剩（ape））或乳蛋白（0.05（标准误0.0018）ape），证实了组织赖氨酸的双重来源（细菌和日粮）。以乳蛋白为参照时，微生物对组织赖氨酸的贡献为0.23（标准误0.006）。
