Molina-Alcaide E, Pascual M R, Cantalapiedra-Hijar G, Morales-García E Y, Martín-García A I
Estación Experimental del Zaidín (Consejo Superior de Investigaciones Científicas), Profesor Albareda, 1, 18008 Granada, Spain.
J Anim Sci. 2009 Apr;87(4):1321-33. doi: 10.2527/jas.2008-1263. Epub 2008 Dec 19.
The effect of replacing concentrate with 2 different feed blocks (FB) on ruminal fermentation and microbial growth was evaluated in goats and in single-flow continuous-culture fermenters. Diets consisted of alfalfa hay plus concentrate and alfalfa hay plus concentrate with 1 of the 2 studied FB. Three trials were carried out with 6 rumen-fistulated Granadina goats and 3 incubation runs in 6 single-flow continuous-culture fermenters. Experimental treatments were assigned randomly within each run, with 2 repetitions for each diet. At the end of each in vivo trial, the rumen contents were obtained for inoculating the fermenters. For each incubation run, the fermenters were inoculated with ruminal fluid from goats fed the same diet supplied to the corresponding fermenter flask. The average pH values, total and individual VFA, and NH(3)-N concentrations, and acetate:propionate ratios in the rumen of goats were not affected (P >or= 0.10) by diet, whereas the microbial N flow (MNF) and efficiency were affected (P <or= 0.001), with the greatest values observed for the diet without FB. In fermenters, the diet affected pH (P<0.001), propionate concentrations (P=0.01), acetate:propionate ratio (P=0.03), carbohydrate digestibility (P >or= 0.05), and total (P=0.02), NH(3) (P=0.005), and non-NH(3) (P=0.02) N flows, whereas the efficiency of VFA production was not affected (P=0.75). The effect of diet on MNF and efficiency depended on the bacterial pellet used as a reference. An effect (P<0.05) of diet on the composition of solid- and liquid-associated bacteria was observed. The compositions of liquid-associated bacteria in the fermenter contents and effluent were similar (P=0.05). Differences (P<0.001) between in vivo and in vitro values for most fermentation variables and bacterial pellet compositions were found. Partial replacement of the concentrate with FB did not greatly compromise carbohydrate fermentation in unproductive goats. However, this was not the case for MNF and efficiency. Differences between the results obtained in vivo and in vitro indicate a need to identify conditions in fermenters that allow better simulation of fermentation, microbial growth, and bacterial pellet composition in vivo. Reduced feeding cost could be achieved with the inclusion of FB in the diets of unproductive goats without altering rumen fermentation.
在山羊和单流连续培养发酵罐中评估了用2种不同的饲料块（FB）替代精料对瘤胃发酵和微生物生长的影响。日粮由苜蓿干草加精料以及苜蓿干草加精料与2种研究的FB中的1种组成。对6只装有瘤胃瘘管的格拉纳迪纳山羊进行了3次试验，并在6个单流连续培养发酵罐中进行了3次培养运行。实验处理在每次运行中随机分配，每种日粮重复2次。在每次体内试验结束时，采集瘤胃内容物用于接种发酵罐。对于每次培养运行，向发酵罐中接种来自饲喂与相应发酵罐瓶中相同日粮的山羊的瘤胃液。日粮对山羊瘤胃中的平均pH值、总挥发性脂肪酸（VFA）和单个VFA、氨态氮（NH₃-N）浓度以及乙酸:丙酸比值没有影响（P≥0.10），而微生物氮流量（MNF）和效率受到影响（P≤0.001），未添加FB的日粮的值最高。在发酵罐中，日粮影响pH（P<0.001）、丙酸浓度（P=0.01）、乙酸:丙酸比值（P=0.03）、碳水化合物消化率（P≥0.05）以及总氮（P=0.02）、氨态氮（P=0.005）和非氨态氮（P=0.02）流量，而VFA产生效率不受影响（P=0.75）。日粮对MNF和效率的影响取决于用作参考的细菌沉淀。观察到日粮对固体和液体相关细菌组成有影响（P<0.05）。发酵罐内容物和流出物中液体相关细菌的组成相似（P=0.05）。发现大多数发酵变量和细菌沉淀组成的体内和体外值之间存在差异（P<0.001）。用FB部分替代精料不会严重影响非生产性山羊的碳水化合物发酵。然而，MNF和效率并非如此。体内和体外获得的结果之间的差异表明需要确定发酵罐中的条件，以便更好地模拟体内的发酵、微生物生长和细菌沉淀组成。在非生产性山羊的日粮中添加FB可以在不改变瘤胃发酵的情况下降低饲养成本。
