Lodman D W, Petersen M K, Clark C K, Wiley J S, Havstad K M, McInerney M J
Montana State University, Bozeman 59717.
J Anim Sci. 1990 Dec;68(12):4361-75. doi: 10.2527/1990.68124361x.
A winter grazing study was conducted to determine whether DL-methionine could replace soybean meal as a N supplement for gestating beef cows. During two winters (Trial 1, n = 51; Trial 2, n = 60), crossbred beef cows grazed native foothill range. Three treatment groups were supplemented with either none (CON), DL-methionine (7.5 g Trial 1 and 9 g Trial 2) in .5 kg beet pulp carrier (BPM) or .4 kg soybean meal (SBM). Cows were supplemented individually every other day. Small differences were noted in cow BW, condition score and blood metabolites. Unsupplemented cows lost the greatest amount of BW (P less than .01) in both trials and lost more (P less than .05) condition during Trial 1 than cows fed BPM or SBM supplements. Blood samples were obtained on two consecutive days during each trial (45 d and 25 d prepartum) and analyzed for blood urea N, total bilirubin, creatinine, albumin, total protein and cholesterol. A treatment x day preparatum interaction (P less than .05) was noted for blood urea. Blood urea nitrogen declined as gestation length increased for CON and SBM cows, but blood urea of BPM-supplemented cows remained low and unchanged. In situ forage digestion was measured in 12 ruminally cannulated cows (four/treatment). In both trials, in situ rate of NDF disappearance was greater (P less than .05) for SBM than for BPM. In Trial 2, a treatment x sampling hour interaction was detected for purine concentration of whole ruminal contents; SBM maintained greater purine concentrations throughout the 48-h supplementation cycle than BPM did. Principal component analysis suggested that ruminal ammonia limited the microbial growth response to DL-methionine. Therefore, alternate-day supplementation of DL-methionine plus beet pulp did not effectively substitute for soybean meal in these trials.
进行了一项冬季放牧研究，以确定DL-蛋氨酸是否可以替代豆粕作为妊娠肉牛的氮补充剂。在两个冬季（试验1，n = 51；试验2，n = 60）期间，杂交肉牛在原生山麓牧场放牧。三个处理组分别不补充（CON）、在0.5千克甜菜粕载体中补充DL-蛋氨酸（试验1为7.5克，试验2为9克）（BPM）或0.4千克豆粕（SBM）。每隔一天对奶牛进行单独补充。在奶牛体重、体况评分和血液代谢物方面发现了微小差异。在两个试验中，未补充的奶牛体重损失最大（P < 0.01），并且在试验1期间比喂食BPM或SBM补充剂的奶牛体况损失更多（P < 0.05）。在每个试验期间（产前45天和25天）连续两天采集血样，并分析血尿素氮、总胆红素、肌酐、白蛋白、总蛋白和胆固醇。发现血尿素存在处理×天数互作（P < 0.05）。CON和SBM奶牛的血尿素氮随着妊娠期延长而下降，但补充BPM的奶牛血尿素保持在较低水平且无变化。在12头装有瘤胃瘘管的奶牛（每个处理4头）中测量了原地牧草消化率。在两个试验中，SBM的中性洗涤纤维原地消失率均高于BPM（P < 0.05）。在试验2中，检测到整个瘤胃内容物嘌呤浓度存在处理×采样时间互作；在整个48小时的补充周期中，SBM的嘌呤浓度始终高于BPM。主成分分析表明，瘤胃氨限制了微生物对DL-蛋氨酸的生长反应。因此，在这些试验中，隔天补充DL-蛋氨酸加甜菜粕不能有效替代豆粕。
