常用粗饲料营养成分和饲用价值分析

通过常规化学分析法和康奈尔净碳水化合物-蛋白质体系(CNCPS)评定不同粗饲料的营养成分并比较其组成差异,结合粗饲料品质评定预测公式评定其饲用价值。结果表明,1)黑麦草、甘薯蔓与牛鞭草的粗蛋白质(CP)、粗脂肪(EE)、可溶性粗蛋白质(SCP)和非蛋白氮(NPN)含量显著高于玉米秸秆和稻草,中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)含量显著低于玉米秸秆和稻草。 2)黑麦草和甘薯蔓的糖类(CA)、快速降解真蛋白(PB₁)含量显著高于其他粗饲料,甘薯蔓、黑麦草和牛鞭草淀粉和果胶(CB₁)、非结构碳水化合物(NSC)和慢速降解真蛋白(PB₃)显著高于稻草和玉米秸秆。稻草的可利用纤维(CB₂)含量显著高于其他粗饲料,玉米秸秆的碳水化合物(CHO)、不可利用碳水化合物(CC)和中速降解蛋白质部分(PB₂)含量显著高于其他粗饲料。3)不同粗饲料氨基酸(AA)组成差异大,提供限制性氨基酸的潜力不同,黑麦草的总氨基酸(TAA)、必需氨基酸(EAA)和限制性氨基酸(LAA)的含量显著高于其他粗饲料,玉米秸秆和稻草最低。4)黑麦草的可消化干物质量(DDM)和粗饲料相对值(RFV)均显著高于其他粗饲料,甘薯蔓的干物质随意采食(DMI)和RFV显著高于牛鞭草,玉米秸秆和稻草的DMI、DDM和RFV均为最低,且两者差异不显著。因此,黑麦草的营养价值最高,其次为牛鞭草和甘薯蔓,玉米秸秆和稻草最低。

Analysis of the nutritional components and feeding values of commonly used roughages

The nutrient composition of different roughages was evaluated using basic chemical analysis and the Cornell net carbohydrate and protein system (CNCPS). Nutrient composition was compared and feeding values calculated using the prediction formula for feeding quality evaluation. The results indicated that the contents of crude protein (CP), ether extract (EE), soluble crude protein (SCP), and non-protein nitrogen (NPN) in Lolium perenne, Hemarthria altissima and sweet potato stem were significantly higher than those in corn stover and rice straw. In contrast, contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) in L. perenne, H. altissima and sweet potato stem were significantly lower than those in corn stover and rice straw. The L. perenne and sweet potato stem had higher levels of sugar (CA) and rapidly degraded pure protein (PB₁) than the other roughages analyzed. Compared to corn stover and rice straw, H. altissima, L. perenne and sweet potato stem had higher levels of starch, pectin (CB1), non-structural carbohydrates (NSC) and slowly degraded pure protein (PB₃). Rice straw had the highest levels of available fiber (CB₂), and corn stover had the highest levels of carbohydrate (CHO), unavailable fiber (CC) and intermediately degraded pure protein (PB₂). The amino acid (AA) components of the roughages were significantly different, with different potentials for supplying limiting amino acid (LAA). Among the roughages analyzed, L. perenne had the highest level of total amino acids (TAA), essential amino-acid (EAA) and LAA, while corn stover and rice straw had the lowest. L. perenne had higher levels of digestible dry matter (DDM) and relative feed value (RFV) than the other roughages. The contents of dry matter intake (DMI) and RFV in sweet potato stem were significantly higher than those in H. altissima, while the contents of DMI, DDM and RFV in corn stover and rice straw were the lowest levels, with no significant differences between them. Therefore, L. perenne has the highest nutrient value and H. altissima and sweet potato stem are mid-range, while corn stover and rice straw have the lowest nutrient value.