0～56日龄放牧羔羊消化道的解剖特点和瘤胃功能变化

Anatomical Changes of Digestive Tract and Rumen Functional Development in Grazing Lamb at the Age of 0-56 d

旨在研究完全放牧条件下羔羊消化道相对质量与相对容积和瘤胃功能的发育特点。选用44只甘肃高山细毛羊公羔,测定0、3、7、14、21、28、42与56日龄胃(前胃、皱胃)、小肠各段和盲肠的相对质量(%活体质量),胃各室相对质量(%全胃质量)、相对容积(%全胃容积)、内容物相对质量(%全胃内容物质量)及瘤胃内容物微生物酶活性和挥发性脂肪酸(VFA)的浓度。结果表明:前胃、小肠、盲肠相对质量随羔羊日龄增大而提高,14～21d前胃与盲肠相对质量增速最快,其次为42～56d;小肠相对质量各阶段增速波动较小。随日龄增长,瘤胃相对质量与相对容积升高,皱胃相应下降,7～14、14～21与42～56d变速较大;0～14d前胃相对容积增速低于相对质量,14d后其增速快于后者,28d后相对容积增速大于相对质量。胃各室内容物的pH相对稳定,瘤胃内容物pH变动于6.03～6.67;0、3、7d部分受试羔羊中被检出纤维素酶比活性的比例随日龄增大,14d后所有受试羔羊均被检出,且纤维素酶比活性随日龄增高。14d蛋白酶活性最高,42d淀粉酶、纤维素酶比活性最高;从3d羔羊瘤胃内容物中即检出乙酸、丙酸、丁酸,其浓度均随日龄增大而升高,VFAs浓度与微生物酶比活性峰值的出现与瘤网胃发育状况并行。结论:羔羊前胃相对质量0～21d增长较快,而此后其增速减慢,是羔羊营养状况改变引起的;本试验条件下,羔羊2月龄断奶较适宜,42d是可接受的最早断奶日龄。

To understand the anatomical development of whole digestive tract and functional development of the rumen in grazing lambs at the age of 0-56 d,forty-four Gansu Merino male lambs were killed and sampled at 0,3,7,14,21,28,42,56 days of age,respectively.The relative weights of gastric ventriculars（% live weight,RWL）of forestomach,abomasum,small intestine and cecum,relative weight（%of whole stomach weight,RWS）and volume（%of whole stomach volume,RCS）of stomach compartments,relative weight of the compartment contents（% of whole stomach contents weight,RWCS）and the pH of the compartment contents were measured;the concentrations of VFA and activity of microorganism enzyme in rumen content were also determined.With the age increasing,RWL of forestomach,small intestine and cecum increased with the faster increasing of forestomach and cecum at day 14-21,followed day 42-56,the increasing of small intestine slowly.RWS and RCS of rumen increased very markably,while these of abomasum reduced,all the changes were faster at day 7-14,14-21 and 42-56.During 0-14 d,RCS was lower than RWS for forestomach,but thereafter the growing was faster for former than that for later,hence the value of RCS exceeded RWS after day 28.With the age increasing,the pH of contents in stomach compartments was stable relatively,the pH of rumen contents ranged from 6.03 to 6.67.0-7 d the ratio of occurring rumen cellulase activities in partial detected lambs increased with the age increasing,after 14 d the enzyme activities had been observed in the all lambs tested,and the activities increased with the age increasing too;the peaks of activities occurred at day 14 for protease and at day 42 for amylase and cellulase.Acetate,propionate and butyrate were found from lambs＇ rumen contents of day 3 and the concentration of acids raised with age increasing.The appearance of peaks of VFAs concentration and activities of the amylase and cellulase were parallel with the development of rumen-reticulum.The faster growing during day 0-21 and thereafter the slower growing for RWS of forestomach was caused by the change of nutrient state of lambs.Under the study condition,lambs＇ weaning is better at 2 month-old,and day 42 is the earliest weaning age accepted.