碳水化合物平衡指数调控绵羊瘤胃功能的研究

碳水化合物平衡指数（CBI）理论是为降低反刍动物瘤胃酸中毒风险、平衡饲粮粗饲料NDF（FNDF）和可降解淀粉（RDS）提出的参数体系。全混合颗粒饲粮（P-TMR）是近年来绵羊育肥生产重要的营养供应方式，由于其精料比例过高且有效纤维不足，易引起绵羊发生瘤胃酸中毒。本研究以FNDF与RDS比值表述CBI，分别利用瘤胃瘘管绵羊和断奶羔羊在P-TMR饲喂模式下研究CBI水平和调整方式（FNDF或RDS）：（1）利用安装瘤胃瘘管的绵羊研究CBI与瘤胃pH的定量关系并明确预防绵羊发生乳酸中毒饲粮CBI下限（2）揭示饲粮CBI水平相同而影响因素不同（FNDF或RDS），不同CBI调整因素对绵羊瘤胃pH及瘤胃功能的影响是否等价（3）通过饲养试验，根据瘤胃上皮损伤程度与功能基因表达明确CBI水平与育肥绵羊瘤胃酸中毒风险的关系，并结合生长育肥性能确定P-TMR适宜的CBI水平。

The theory of carbohydrate balance index (CBI) is used to reduce the risk of ruminal acidosis and balance the dietary ratios of forage NDF to rumen degradable starch. The pellet total mixed ration (P-TMR) is a common used nutrients supplementation strategy for fattening sheep. But the P-TMR diets usually have a higher proportion of concentrate and lower effective fiber compare with TMR. Study the appropriate dietary forage NDF to RDS ratios can provide some indications to reducing the risk of SARA for fattening sheep when they are intake P-TMR. In the present research, we define the CBI as the ratio of dietary FNDF to RDS, and study the levels of CBI and factors that affect CBI (FNDF or RDS): (1) sheep with rumen fistula are used to study the correlation between the CBI and rumen pH, and provide the baseline of dietary FNDF/RDS that avoid the risk of lactate acidosis for sheep. (2) to compare the equivalence of the change of FNDF or RDS that affect CBI on the ruminal pH and rumen function. (3) we use the feeding trial to evaluate the tolerance of sheep to ruminal acidosis base on rumen epithelium damage condition with different level of CBI. The growth performances are also used to define the appropriate range of CBI in the P-TMR for fattening sheep.