Burrin D G, Britton R A, Ferrell C L, Bauer M L
Department of Animal Science, University of Nebraska, Lincoln 68583-0908.
J Anim Sci. 1992 Apr;70(4):1137-45. doi: 10.2527/1992.7041137x.
Thirty-two crossbred wether lambs were assigned to a feed intake level of either ad libitum (ADLIB) for maximum rate of growth or restricted to maintain body weight (MAINT) throughout a 21-d period. At 7-d intervals (d 0.7, 14, and 21), four lambs per treatment were slaughtered to obtain measurements of visceral organ protein synthetic capacity and tissue composition. Protein synthetic capacity was assessed by in vitro [14C]valine incorporation and tissue RNA, DNA, and protein contents. Concentrations of protein and RNA were not significantly affected in most tissues measured. However, for liver, duodenal, and jejunal tissue, DNA concentrations in ADLIB lambs were lower (P less than .05) than in MAINT lambs. Ratios of protein:DNA in most organs were higher (P less than .05) in ADLIB than in MAINT lambs. During the 21-d period, liver and small intestinal protein and RNA mass were higher (P less than .10) in ADLIB than in MAINT lambs, and DNA mass was unaffected. Also during the 21-d period, the average total mass of ruminal protein, RNA, and DNA in ADLIB lambs was higher (P less than .05) than in MAINT lambs. Estimates of valine incorporation and ratios of RNA:protein seemed to reflect protein synthetic capacity of the visceral tissues measured; however, the effect of level of feed intake on these measurements was equivocal. These data suggest that the level of feed intake affected visceral organ mass through changes in cellular hypertrophy.
32只杂交去势公羔羊被分配到两种采食量水平之一，一种是自由采食（ADLIB）以实现最大生长速度，另一种是限饲以维持体重（MAINT），整个试验期为21天。每隔7天（第0、7、14和21天），每种处理选取4只羔羊进行屠宰，以测量内脏器官蛋白质合成能力和组织组成。通过体外[14C]缬氨酸掺入以及组织RNA、DNA和蛋白质含量来评估蛋白质合成能力。在大多数测量的组织中，蛋白质和RNA的浓度没有受到显著影响。然而，对于肝脏、十二指肠和空肠组织，自由采食组羔羊的DNA浓度低于维持体重组羔羊（P<0.05）。自由采食组羔羊大多数器官的蛋白质:DNA比值高于维持体重组羔羊（P<0.05）。在21天的试验期内，自由采食组羔羊的肝脏和小肠蛋白质及RNA总量高于维持体重组羔羊（P<0.10），而DNA总量未受影响。同样在21天的试验期内，自由采食组羔羊瘤胃蛋白质、RNA和DNA的平均总量高于维持体重组羔羊（P<0.05）。缬氨酸掺入量的估计值以及RNA:蛋白质比值似乎反映了所测量内脏组织的蛋白质合成能力；然而，采食量水平对这些测量值的影响并不明确。这些数据表明，采食量水平通过细胞肥大的变化影响内脏器官质量。
