摘要
The average rumen rate of passage of dietary NDF (kNDF) of mixed forage diets for cows was estimated indirectly as the value which, together with the values of kinetic degradation measured for each ingredient under standardised conditions, allowed the calculation of the NDF effective degradability equal to the NDF digestibility. Forages were grown on a permanent grassland divided into equal plots and subjected to three cutting frequencies (two, three and four cuts per year, FC) and two types of fertilisation (slurry only or slurry plus mineral N). Within each FC, the forages from the individual cuts, produced from plots submitted to the same type of N fertilisation, were mixed in proportion to their seasonal yield. Each of these six mixed diets were fed ad libitum to two or three lactating cows (a total of 15 cows), with the proviso that three groups of five cows received the mixtures corresponding to 2, 3 and 4 FC, respectively. Another three similar groups received the same diets supplemented with 25% of dietary dry matter intake (DMI) of concentrate. The cows were kept in stalls and fed the diets for 12 weeks, using the fifth week to measure the dietary NDF digestibility. Samples of forages and concentrate were used to measure the NDF in situ degradability in standardised conditions. The type of grassland fertilisation caused no statistically significant effects. DMI increased with the inclusion of concentrate (111 vs 133 g/kg LW0.75, PPPkNDF followed the DMI variations, with the highest values in correspondence with the highest DMI: the inclusion of concentrate caused a 25% increase in the estimated kNDF (from 1.49 to 1.84%/h, PkNDF (1.42, 1.56 and 2.03%/h, respectively for FC 2, 3 and 4, PkNDF gave values comparable to those obtained in other experiments with direct measurements and demonstrated the sensitivity of the estimates of kNDF to variations of intake in lactating cows.
摘要译文
奶牛混合饲料日粮的平均瘤胃率（k NDF）间接估算为其值，与在标准条件下测量的每种成分的动力学降解值一起，允许计算NDF有效降解率等于NDF消化率。牧草生长在永久性草地上，分成相同的地块，并经受三次切割频率（每年减少两次，三次和四次，FC）和两种类型的施肥（仅浆液或浆液加矿物质N）。在每个FC中，来自单个切割的牧草，由提交到相同类型的N施肥的地块产生，与季节性产量成比例混合。这六种混合饮食中的每一种都随意喂给两到三头泌乳母牛（共15头母牛），条件是三组五头奶牛分别接受对应于2,3和4 FC的混合物。另外三个相似的组接受相同的饮食，补充25％的饮食干物质摄入量（DMI）浓缩物。将奶牛放在摊位中喂养12天，用第五周测量膳食NDF的消化率。饲草和浓缩物样品用于测量标准条件下的NDF原位降解性。草地施肥类型没有带来统计学上的显着影响。随着浓缩物的加入，DMI增加（111 vs 133 g / kg LW sup 0.75 / sup，PPPk NDF遵循DMI变化，最高值与最高DMI相对应：包含浓缩物导致估计k NDF增加25％（从1.49％到1.84％/ h，Pk NDF（分别为FC2,3和4的1.42,1.56和2.03％/ h，Pk NDF给出的值与直接测量的其他实验中获得的值相当，并证明了k NDF估计对泌乳奶牛摄入量变化的敏感性。
MauroSpanghero[a];LeonhardGruber[b];BrunoStefanon[a];PieroSusmel[a];. The estimation of the rumen rate of passage of dietary NDF from degradability and digestibility data in cows[J]. Livestock Production Science, 1999,60(1): 71-79