1INRA-UR 143, Unité de Recherches Zootechniques, Prise d'eau, Petit-bourg, 97170 Guadeloupe, French West Indies.
Animal. 2010 Mar;4(3):439-45. doi: 10.1017/S1751731109991194.
The effects of defaunation on growth and digestion were measured in sheep fed fresh Digitaria decumbens grass cut at four stages of regrowth 14, 28, 42, and 56 days, and with different protein to energy (P/E) ratios. Two completely randomized designs trials (growth and digestion) were conducted using faunated animals, defaunated rams and protozoa free lambs. The digestion trial: eight faunated and eight defaunated rams fitted with ruminal and duodenal cannulas were fed 4 diets (diets D1 to D4) to measure digestion parameters. The dietary P/E ratios were 120 (D1), 130 (D2), 130 (D3), and 140 (D4) g PDIN/UFL (Protein Digested in the small Intestine supplied by microbial protein from rumen-degraded protein/Feed Unit for Lactation) and the grass stages of regrowth were 56, 42, 28, and 14 days, respectively. Increasing the dietary P/E ratios increased dry matter intake (DMI) and the total tract digestibility of organic matter (OM), NDF and CP. Defaunation decreased DMI, except for rams fed D4 diet. Defaunation also decreased total tract digestibility of OM except for rams fed D1 diet and that of NDF except for rams fed D1 and D4 diets. Increasing the dietary P/E ratios also increased nitrogen intake and ammonia (NH3) concentration in the rumen, whereas defaunation decreased them. The dietary P/E ratio increased non-NH3 nitrogen and microbial nitrogen duodenal flows and microbial efficiency. Defaunation did not affect duodenal flows of neither non-NH3 nitrogen and microbial nitrogen or microbial efficiency. The growth trial: 20 faunated and 20 protozoa free lambs were fed four diets (diets D5 to D8) to measure their average daily gain (ADG). The dietary P/E ratios were 60 (D5), 70 (D6), 80 (D7) and 100 (D8) g PDIN/UFL and the stages of regrowth were 56, 42, 28, and 14 days, respectively. DMI of lambs increased with P/E ratio. Protozoa free lambs had greater DMI than faunated ones when fed D7 diet (80.8 v. 74.9 g/kg LW0.75, respectively). The ADG of the lambs increased with P/E ratio. Fed on the same D5 diet, protozoa free lambs had greater ADG than faunated lambs (29.8 v. 11.6 g/day, respectively). In conclusion, animal response to defaunation was modulated by the P/E ratio of the D. decumbens grass diets. Defaunation increased ADG of lambs fed forage with the lowest P/E ratio, while digestion and nitrogen duodenal flows of rams fed the lowest P/E ratio were not affected.
本研究旨在评估在绵羊分别采食不同再生长阶段（14、28、42 和 56 天）和不同蛋白能量（P/E）比（120、130、130 和 140 g PDIN/UFL）的新鲜垂穗披碱草时，去纤毛虫对其生长和消化的影响。试验采用完全随机设计，分别使用有纤毛虫、去纤毛虫绵羊和原虫自由绵羊进行生长和消化试验。消化试验中，8 只有纤毛虫绵羊和 8 只去纤毛虫绵羊通过瘤胃和十二指肠瘘管饲喂 4 种饲粮（饲粮 D1 至 D4），以测量消化参数。饲粮 P/E 比分别为 120（D1）、130（D2）、130（D3）和 140（D4）g PDIN/UFL（瘤胃降解蛋白提供的微生物蛋白可消化小肠内蛋白/泌乳单位），再生长阶段分别为 56、42、28 和 14 天。随着饲粮 P/E 比的增加，干物质采食量（DMI）和有机物、NDF 和 CP 的全肠道消化率增加。去纤毛虫降低了 DMI，但 D1 饲粮组绵羊除外。除了 D1 饲粮组绵羊外，去纤毛虫还降低了有机物的全肠道消化率，除了 D1 和 D4 饲粮组绵羊外，还降低了 NDF 的全肠道消化率。增加饲粮 P/E 比还增加了氮摄入量和瘤胃中氨（NH3）浓度，而去纤毛虫降低了它们。饲粮 P/E 比增加了非 NH3 氮和微生物氮的十二指肠流量以及微生物效率。去纤毛虫对非 NH3 氮和微生物氮的十二指肠流量或微生物效率没有影响。生长试验中，20 只有纤毛虫绵羊和 20 只原虫自由绵羊饲喂 4 种饲粮（饲粮 D5 至 D8），以测量其平均日增重（ADG）。饲粮 P/E 比分别为 60（D5）、70（D6）、80（D7）和 100（D8）g PDIN/UFL，再生长阶段分别为 56、42、28 和 14 天。绵羊的 DMI 随 P/E 比增加而增加。当饲喂 D7 饲粮（分别为 74.9 和 80.8 g/kg LW0.75）时，原虫自由绵羊的 DMI 大于有纤毛虫绵羊。绵羊的 ADG 随 P/E 比增加而增加。饲喂相同的 D5 饲粮时，原虫自由绵羊的 ADG 大于有纤毛虫绵羊（分别为 29.8 和 11.6 g/天）。总之，动物对去纤毛虫的反应受垂穗披碱草饲粮 P/E 比的调节。去纤毛虫增加了采食最低 P/E 比饲粮绵羊的 ADG，而采食最低 P/E 比饲粮绵羊的消化和氮十二指肠流量不受影响。
