Alexander L S, Qu A, Cutler S A, Mahajan A, Lonergan S M, Rothschild M F, Weber T E, Kerr B J, Stahl C H
Department of Animal Science, Iowa State University, Ames, IA 50010, USA.
J Anim Sci. 2008 Oct;86(10):2585-95. doi: 10.2527/jas.2007-0692. Epub 2008 May 23.
Concern over the environmental effect of P excretion from pig production has led to reduced dietary P supplementation. To examine how genetics influence P utilization, 94 gilts sired by 2 genetic lines (PIC337 and PIC280) were housed individually and fed either a P-adequate diet (PA) or a 20% P-deficient diet (PD) for 14 wk. Initially and monthly, blood samples were collected and BW recorded after an overnight fast. Growth performance and plasma indicators of P status were determined monthly. At the end of the trial, carcass traits, meat quality, bone strength, and ash percentage were determined. Pigs fed the PD diet had decreased (P < 0.05) plasma P concentrations and poorer G:F (P < 0.05) over the length of the trial. After 4 wk on trial, pigs fed the PD diet had increased (P < 0.05) plasma 1,25(OH)(2)D(3) and decreased (P < 0.05) plasma parathyroid hormone compared with those fed the PA diet. At the end of the trial, pigs fed the PD diet had decreased (P < 0.05) BW, HCW, and percentage fat-free lean and tended to have decreased LM area (P = 0.06) and marbling (P = 0.09) and greater (P = 0.12) 10th-rib backfat than pigs fed the PA diet. Additionally, animals fed the PD diet had weaker bones and also decreased (P < 0.05) ash percentage and increased (P < 0.05) concentrations of 1alpha-hydroxylase and parathyroid hormone receptor mRNA in kidney tissue. Regardless of dietary treatment, PIC337-sired pigs consumed more feed and gained more BW than their PIC280-sired counterparts (P < 0.05) during the study. The PIC337-sired pigs also had greater (P < 0.05) HCW, larger (P < 0.01) LM area, and tended to have (P = 0.07) greater dressing percentage. Meat from the PIC337-sired pigs also tended to have greater (P = 0.12) concentrations of lactate but decreased (P = 0.07) concentrations of total glucose units 24 h postslaughter. Although plasma 1,25(OH)(2)D(3) concentrations were elevated (P < 0.05) in all the animals fed the PD diet, this elevation due to P deficiency tended (P = 0.09) to be greater in the PIC337-sired pigs after 12 wk on the treatment. The PIC337-sired pigs had stronger (P < 0.01) bones with greater ash percentage than the PIC280-sired pigs. The difference in the strength of the radii between the PIC337-sired pigs fed the PA and PD diets was greater than their PIC280-sired counterparts, which resulted in sire line x treatment interactions (P < 0.05). These data indicate differing mechanisms of P utilization between these genetic lines. Elucidating these mechanisms may lead to strategies to increase efficiency of growth in a more environmentally friendly manner.
对养猪生产中磷排泄所产生环境影响的担忧，已导致日粮中磷添加量减少。为研究遗传因素如何影响磷的利用，将94头由2个遗传品系（PIC337和PIC280）所生的后备母猪单独饲养，并分别饲喂磷充足日粮（PA）或低20%磷日粮（PD），持续14周。试验开始时及每月一次，在禁食过夜后采集血样并记录体重。每月测定生长性能和磷状态的血浆指标。试验结束时，测定胴体性状、肉质、骨强度和灰分百分比。在整个试验期间，饲喂PD日粮的猪血浆磷浓度降低（P<0.05），生长肥育比（G:F）较差（P<0.05）。试验4周后，与饲喂PA日粮的猪相比，饲喂PD日粮的猪血浆1,25(OH)₂D₃升高（P<0.05），血浆甲状旁腺激素降低（P<0.05）。试验结束时，饲喂PD日粮的猪体重、热胴体重和无脂瘦肉百分比降低（P<0.05），眼肌面积（P=0.06）和大理石花纹（P=0.09）有降低趋势，第10肋背膘厚比饲喂PA日粮的猪更厚（P=0.12）。此外，饲喂PD日粮的动物骨骼较弱，肾脏组织中灰分百分比降低（P<0.05），1α-羟化酶和甲状旁腺激素受体mRNA浓度升高（P<0.05）。在研究期间，无论日粮处理如何，PIC337品系所生的猪比PIC280品系所生的猪采食更多饲料，体重增加更多（P<0.05）。PIC337品系所生的猪热胴体重也更大（P<0.05），眼肌面积更大（P<0.01），屠宰率有更大趋势（P=0.07）。PIC337品系所生的猪的肉在屠宰后24小时乳酸浓度有更高趋势（P=0.12），但总葡萄糖单位浓度降低（P=0.07）。尽管所有饲喂PD日粮的动物血浆1,25(OH)₂D₃浓度均升高（P<0.05），但在处理12周后，PIC337品系所生的猪因磷缺乏导致的这种升高有更大趋势（P=0.09）。PIC337品系所生的猪骨骼比PIC280品系所生的猪更强壮（P<0.01），灰分百分比更高。饲喂PA和PD日粮的PIC337品系所生的猪之间桡骨强度差异大于PIC280品系所生的猪，这导致父本品系×处理交互作用（P<0.05）。这些数据表明这些遗传品系之间磷利用的机制不同。阐明这些机制可能会带来以更环保方式提高生长效率的策略。
