山羊对^(15)N-尿素消化利用的研究

STUDIES ON THE DIGESTION AND UTILIZATION OF UREA-NITROGEN ^(15)N IN GOATS

在同时装有十二指肠 T 形瘘管和瘤胃瘘管的山羊上进行3系列试验,研究山羊对^(15)N-尿素的利用.日粮中尿素占1.34%,粗蛋白含量为16.56%.结果表明:十二指肠食糜中细菌氮(BN)和氨氮(NH_3-N)都含有^(15)N.两种组分中^(15)N 含量分别占2.80%和4.65%;非氨氮(NAN)中 BN 占82.49%,瘸胃细菌蛋白合成效率平均为14.29BCP·g/100g.DOM.^(15)N-尿素引入瘤胃后,8～12小时尿中^(15)N 排出达到最高峰,4天后才在粪中出现峰值.一次由瘤胃引入^(15)N-尿素后第7天,肝、血液、瘤胃壁氮中^(15)N 的比例较高,而肌肉中较低.

Two series experiments were made on three wethers.In 1st series,17β-estradiol(E_2)was injected intramuscularily by 0.1 mg per kilogram body weight.After injection the levelof E_2 in blood and rumen fluid raised.It indicated that E_2 might enter into rumen fromblood.Food intake,volume and turnover of rumen fluid,total dehydrogenase activity(TDHA)and TVFA all deercased significantly;the percentage of acetate and butyrate in-creased while that of propiorate decreased;the fermentation pattern changed frompropionic to acetic.It suggested that the decrease of food intake correlated with the inhibi-tion of rumen evacuation and change of fermentation pattern.During control period,noE_2 was found in blood while in rumen had 89.2±1.2 pg/ml.It showed that rumen mi-crobes might turn some substances into E_2.In 2nd series,the decrease of TDHA and TVFAwith unchanged fermentation pattern were shown when 6.1×10^(-6) molL^(-1) E_2 was add(?)dinto rumen fluid in vitro.It indicated that E_2 could inhibit rumen microbial metabolismthrough either direct or indirect way.