本试验旨在研究不同代乳条件下1~35日龄羔羊瘤胃及其微生物群落的发育。选取56只初生重(3 380±328) g的小尾寒羊公羊,从1日龄起分别饲喂牛奶粉代乳(milk powder substitute,MS,28只)或鱼粉代乳(fish meal substitute,FS,28只),并在21日龄将饲喂2种代乳的羔羊各8只转喂开食料。在7、14、21、28和35日龄分别宰杀4只,进行瘤胃液细菌和原虫分类计数,测定瘤胃液真菌数量、挥发性脂肪酸和氨态氮(NH₃-N)浓度,瘤网胃重量和结构形态指标。结果表明:1)饲喂MS羔羊瘤胃在7日龄即有细菌(85.47×10⁹个/mL,97.4%为瘤胃球菌)和原虫(1.10×10⁵个/mL),且总数均随日龄增加而增加。7日龄羔羊瘤胃液真菌数量较少,直到35日龄时才较多。羔羊瘤胃在7日龄即有总挥发性脂肪酸(TVFA,乙酸为主),但浓度在21日龄后才随日龄增加大幅上升。7日龄羔羊瘤胃液NH₃-N浓度为33.2 mg/dL。饲喂MS的羔羊瘤网胃重量、瘤胃乳头长度和宽度随日龄增加而增加。2)与饲喂MS相比,饲喂FS的羔羊7日龄瘤胃液细菌和原虫总数分别减少30.8%(P<0.01)和27.3%(P>0.05),瘤胃液TVFA和NH₃-N浓度随日龄增加波动变化,35日龄瘤网胃重减少17.1%(P>0.05),瘤胃乳头长度和宽度分别减少16.0%(P<0.05)和增加39.4%(P>0.05)。3)21日龄给羔羊转喂开食料,原先饲喂MS羔羊28日龄瘤胃液细菌总数增加49.7%(P0.01),原虫总数减少50.3%(P<0.01),TVFA浓度升高158.8%(P<0.01),瘤网胃重增加14.0%(P>0.05)、瘤胃乳头长度变短43.3%(P<0.01),宽度增加61.8%(P<0.01);瘤胃液真菌数量在35日龄时显著增加。4)21日龄给羔羊转喂开食料,原先饲喂FS羔羊28日龄瘤胃液细菌总数增加21.1%(P>0.05),原虫总数减少60.4%(P<0.01),TVFA和NH₃-N浓度各降低43.5%(P>0.05)和49.1%(P<0.05),瘤胃乳头长度和宽度分别减少23.1%(P<0.05)和11.2%(P>0.05);在35日龄时几乎没有真菌存在。由本试验得出结论,羔羊7日龄瘤胃消化发育即已开始,饲喂FS或21日龄转喂开食料都会影响瘤胃及其微生物群落的发育。

This experiment was conducted to investigate the development of rumen and its microbiocoenosis of lambs at 1 to 35 days of age under different milk replacing conditions. Fifty six Small Tail Han lambs with the birth body weight of (3 380±328) g were selected and fed milk powder substitute (MS, 28 lambs) and fish meal substitute (FS, 28 lambs) since 1 day of age, respectively. At 21 days of age, eight lambs from each of the two milk substitute treatments were turned to feed a starter. At the age of 7, 14, 21, 28 and 35 days, four lambs were sacrificed, respectively, to determine the differential count of the bacteria and protozoa, the number of fungus, the concentrations of volatile fatty acid (VFA) and ammonia nitrogen (NH₃-N) in rumen fluid, and the weight and morphological structure indices of rumen-reticulum. The results showed as follows: 1) there were protozoa (1.1×10⁵ cells/mL) and bacteria (85.47×10⁹ cells/mL, 97.4% Ruminococcus) in rumen fluid of lambs fed MS at the age of 7 days , and the total number increased with aging. There was a little of fungus in rumen fluid at 7 days of age, and the number became more until 35 days of age. Total VFA (mainly as acetic acid) was already produced in rumen of lambs at the age of 7 days, and the concentration increased obviously after the age of 21 days. The NH₃-N concentration in rumen fluid of lamb at 7 days of ages was 33.2 mg/dL. The weight of rumen-reticulum, and the height and width of rumen papilla of lambs fed MS increased with aging. 2) Compared with MS, the total numbers of protozoa and bacteria in rumen fluid of lambs fed FS were decreased by 30.8% (P<0.01) and 27.3% (P>0.05), respectively, the total VFA and NH₃-N concentrations in rumen fluid were changed dramatically with aging, the weight of rumen-reticulum was decreased by 17.1% at 35 days of age (P>0.05), the rumen papilla height was decreased by 16.0% (P<0.05), and the rumen papilla width was increased by 39.4% (P>0.05). 3) When the lambs were fed the starter instead of milk substitute at 21 days of age, the total number of bacteria in rumen fluid of lambs previously fed MS was increased by 49.7% (P<0.01), the total number of protozoa was decreased by 50.3% (P<0.01), the total VFA concentration was increased by 158.8% (P<0.01), and the weight of rumen-reticulum and the rumen papilla width were increased by 14.0% (P>0.05) and 61.8%(P<0.01), respectively, however, the rumen papilla height was shortened by 43.3% (P<0.01); the fungi number in rumen fluid was increased largely at 35 days of age. 4) When the lambs were fed the starter instead of milk substitute at 21 days of age, the total number of bacteria in rumen fluid was increased by 21.1% (P>0.05), the total number of protozoa was decreased by 60.4% (P<0.01), the total VFA and NH₃-N concentrations were decreased by 43.5% (P>0.05) and 49.1%(P<0.05), respectively, and the height and the width of rumen papilla were shortened by 23.1% (P<0.05) and 11.2% (P>0.05), respectively; there was little fungi in rumen fluid of lambs at 35 days of age. In conclusion, the development of rumen digestion of lambs starts at 7 days of age; feeding FS and starter both affects stable development of rumen and its microbiocoenosis.