Kawas J R, Jorgensen N A, Lu C D
Dept. of Dairy Sci, University of Wisconsin, Madison 53706.
J Anim Sci. 1990 Dec;68(12):4376-86. doi: 10.2527/1990.68124376x.
Four wethers fitted with ruminal, duodenal and ileal cannulas were used to study effects of maturity of alfalfa hay on intake, digestion and rate of passage of nutrients in various sites of the digestive tract. Pre-, early-, and mid-bloom hays were harvested from the same field; full-bloom hay was acquired from elsewhere due to wether conditions. Dry matter intake decreased (P less than .05) as intakes of NDF and ADF increased. This was attributed to decreased digestibility and increased retention time of undigested residues. Digestion of OM in the stomach (% of intake) was 44.2, 47.4, 38.8 and 35.1 for pre-, early-, mid- and full-bloom hay, respectively. Digestion of ADF in the stomach was lower for mid-bloom than for pre-and early-bloom hay (P less than .05). Degradation of alfalfa protein in the rumen was 94, 88, 81 and 78% for pre-, early-, mid- and full-bloom hay, respectively. Concentration of ruminal NH3 N, flow of N at the duodenum, fecal N and urinary N decreased of the hay and to N intake. Digestion of N in the small intestine (g/d) decreased as maturity advanced (P less than .05). Duodenal flow of total amino acids was greater (P less than .05) when animals consumed pre-bloom hay than when they consumed more mature hays. Relative feed value calculated from the detergent fiber analysis correlated with actual value determined biologically (r = +.81). Intake and site of nutrient digestion of alfalfa hay were influenced by the stage of maturity at harvest.
选用4只装有瘤胃、十二指肠和回肠瘘管的阉羊，研究苜蓿干草成熟度对消化道各部位养分摄入量、消化率和通过率的影响。初花期、盛花期和盛花期干草取自同一地块；由于天气条件，盛花期干草从其他地方获取。随着中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）摄入量的增加，干物质摄入量下降（P<0.05）。这归因于消化率降低和未消化残渣滞留时间增加。初花期、盛花期、盛花期和盛花期干草在胃中有机物（占摄入量的百分比）的消化率分别为44.2%、47.4%、38.8%和35.1%胃中酸性洗涤纤维的消化率盛花期低于初花期和盛花期干草（P<0.05）。初花期、盛花期、盛花期和盛花期干草在瘤胃中苜蓿蛋白的降解率分别为94%、88%、81%和78%。瘤胃氨氮浓度、十二指肠氮流量、粪便氮和尿氮随着干草成熟度的增加而降低，与氮摄入量呈负相关。随着成熟度的提高，小肠中氮的消化量（克/天）下降（P<0.05）。动物采食初花期干草时十二指肠总氨基酸流量大于采食成熟度较高的干草时（P<0.05）。由洗涤剂纤维分析计算得到的相对饲料价值与生物学测定的实际价值相关（r=+0.81）。苜蓿干草的摄入量和养分消化部位受收获时成熟度阶段的影响。
