Hanks D R, Judkins M B, McCracken B A, Holcombe D W, Krysl L J, Park K K
School of Veterinary Medicine, University of Nevada, Reno 89557-0104.
J Anim Sci. 1993 Oct;71(10):2809-14. doi: 10.2527/1993.71102809x.
Four pregnant and four nonpregnant, ruminally cannulated beef cows were used to evaluate the effects of the last trimester of pregnancy on digesta kinetics and ruminal fermentation. Before breeding, cows were allotted randomly either to pregnant (PR) or to nonpregnant (NP) groups; PR cows were bred at the first estrus after synchronization. All cows were fed long-stem fescue hay at 15 g of DM/kg of BW based on BW 120 d before parturition of pregnant cows (average BW of 642 kg). Collection periods, each lasting 9 d, began at 96, 68, 41, and 10 +/- 1.3 d before parturition. Particulate passage rate was greater (P < .05) and retention times and gastrointestinal fill were less (P < .05) for PR than for NP cows. Apparent total tract DM digestion, rate and extent (96-h in situ incubation) of NDF disappearance, and ruminal fluid kinetics were not affected (P > .10) by pregnancy. A physiological state x sampling day interaction was noted (P < .05) for ruminal NH3 N, total VFA concentrations, and molar proportions of butyrate. Ruminal pH and individual VFA proportions, however, did not differ (P > .10) between PR and NP cows, except for valerate, which was less (P < .05) for PR than NP cows. Results suggest that in late pregnancy with restricted feeding, passage rate of particulates increases without substantial changes in fermentation or extent of digestion.
选用4头怀孕和4头未怀孕的瘤胃插管肉牛来评估妊娠后期对消化物动力学和瘤胃发酵的影响。配种前，将母牛随机分为怀孕组（PR）或未怀孕组（NP）；PR组母牛在同期发情后的第一次发情期进行配种。根据怀孕母牛分娩前120天的体重（平均体重642千克），所有母牛均以15克干物质/千克体重的量饲喂长茎羊茅干草。收集期均为9天，分别在分娩前96、68、41和10±1.3天开始。PR组母牛的颗粒通过率更高（P<.05），滞留时间和胃肠充盈度更低（P<.05）。妊娠对表观全消化道干物质消化率、中性洗涤纤维消失率和程度（96小时原位培养）以及瘤胃液动力学没有影响（P>.10）。观察到瘤胃氨氮、总挥发性脂肪酸浓度和丁酸摩尔比例存在生理状态×采样日的交互作用（P<.05）。然而，PR组和NP组母牛的瘤胃pH值和单个挥发性脂肪酸比例没有差异（P>.10），但戊酸除外，PR组母牛的戊酸含量低于NP组（P<.05）。结果表明，在妊娠后期限饲的情况下，颗粒通过率增加，而发酵或消化程度没有实质性变化。
