外流速率实测与参考对羊常用饲料瘤胃有效降解率的影响

Effects of Measured Outflow Rate and Reference Outflow Rate on Ruminal Effective Degradability of Common Feedstuffs of Sheep

本研究旨在测定半细毛羊6种常用饲料瘤胃外流速率,并分析外流速率实测值与普遍采用的参考值对所测饲料瘤胃有效降解率的影响。选用16只3周岁、健康状况良好、体重63~65 kg的云南半细毛羊公羊作为试验动物,其中4只装有永久性瘤胃瘘管。4只瘘管羊只用来测定铬标记饲料干物质回收率,12只非瘘管羊用来测定瘤胃外流速率。待测瘤胃外流速率的6种饲料分别为豆粕、菜籽粕、玉米、鸭茅、大豆秸秆和小麦秸秆。结果表明:1)采食豆粕、菜籽粕、玉米3种铬标记精饲料后粪中铬含量达到高峰的时间为24~28 h,采食鸭茅、大豆秸秆、小麦秸秆3种铬标记粗饲料后则为24~36 h。2)不同饲料之间瘤胃外流速率有差异,豆粕、菜籽粕、玉米、鸭茅、大豆秸秆、小麦秸秆的瘤胃外流速率分别为7.30%/h、7.49%/h、6.84%/h、5.02%/h、5.59%/h、3.97%/h。3)基于外流速率实测值与参考值计算所得6种饲料干物质、有机物和粗蛋白质有效降解率差异较大,且采用实测值计算所得数值全部低于采用参考值计算所得数值。由此可见,基于外流速率实测值计算所得瘤胃有效降解率与基于外流速率参考值计算所得瘤胃有效降解率差异较大,在利用瘤胃尼龙袋法测定饲料瘤胃有效降解率的实际研究工作中,建议对饲料瘤胃外流速率进行实测。

This experiment was conducted to determine the ruminal outflow rate of 6 kinds of common feedstuffs for semi-wool sheep,and to analyze the effects of the actual measured value and the commonly used reference value of outflow rate on the determination of the rumen effective degradability of feedstuffs.Six healthy Yunnan semi-wool male sheep at the age of 3 years and with the body weight of 63 to 65 kg were selected as experimental animals,and four of them fitted with permanent ruminal cannula.Four cannula sheep were used to determine the dry matter recovery rate of chromium mordanted feedstuffs,and twelve normal sheep were used to determine the ruminal outflow rate of soybean meal,rapeseed meal,corn,cocksfoot,soybean straw and wheat straw.The results showed as follows:1)the fecal chromium content of three chromium mordanted concentrates soybean meal,rapeseed meal and corn reached crest value at 24 to 28 h after feeding,while for three chromium mordanted roughages cocksfoot,soybean straw and wheat straw,it was 24 to 36 h.2)There were differences in the ruminal outflow rates of different feedstuffs,the ruminal outflow rate for soybean meal,rapeseed meal,corn,cocksfoot,soybean straw and wheat straw was 7.30%/h,7.49%/h,6.84%/h,5.02%/h,5.59%/h and 3.97%/h,respectively.3)The differences of effective degradability of dry matter,organic matter and crude protein calculated by actual measured and reference values of outflow rate were significant,and the data calculated by actual measured values were all lower than those calculated by actual measured values.It is concluded that there is significant difference between the ruminal effective degradability using actual measured value and the ruminal effective degradability using reference value.Therefore,we recommend to measure the feedstuffs ruminal outflow rate when using the rumen nylon bag method to determine the ruminal effective degradability in actual research work.