Veum T L, Ledoux D R, Raboy V
Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2007 Apr;85(4):961-71. doi: 10.2527/jas.2006-453. Epub 2006 Dec 18.
A 28-d experiment was conducted using 45 crossbred barrows with an average initial BW of 9.5 kg and age of 35 d to evaluate low-phytate barley (LPB) mutants (M) M422, M635, and M955, which were hulled, near-isogenic progeny of the normal barley (NB) Harrington and had 47, 66, and 80% less phytic acid, respectively, than NB. A hull-less LPB, M422-H, which was not near-isogenic to the other cultivars, was also evaluated. Apparent nutrient balance, bone measurements, and growth performance were the response criteria evaluated. The barrows were fed the diets to appetite in meal form in individual metabolism crates. Barley and soybean meal were the only sources of phytic acid. Dietary protein supplementation and ME/kg were equalized in all diets. The treatments were diets containing NB, M422, M635, or M422-H without or with added inorganic P (iP), or M955 without added iP. Diets with added iP contained 0.30% available P (aP), the same concentration of aP provided by the diet containing M955 without added iP. There were linear increases (P < or = 0.02) in ADG, G:F, metacarpal and radius bone strength, and fat-free dry weight, and in the absorption and retention (g/d and % of intake) of P and Ca with increasing dietary concentration of aP from the near-isogenic cultivars NB, M422, M635, or M955 without added iP. There were linear decreases in the grams (P < or = 0.02) and percentages (P < 0.001) of P and Ca excreted per day with increasing dietary concentration of aP without added iP. There were no responses for N or energy balance. Growth performance and bone response criteria did not differ for barrows fed the diet containing M955 or the near-isogenic diets containing NB, M422, or M635 with added iP. However, barrows fed the diet containing M955 had greater (P < or = 0.02) percentages of P, N, and energy absorption and retention, Ca absorption, and DM digestibility and had less (P < or = 0.02, g/d and %) excretion of P, N, energy, and Ca (g) per day than barrows fed the diets containing the near-isogenic NB or LPB cultivars with added iP. When dietary aP was equalized with iP, the excretion of P in feces plus urine (g/d) was reduced by 20.2, 27.9, and 44.6%, respectively, in barrows fed the diets containing M422 + iP, M635 + iP, or M955 compared with barrows fed the diet containing NB + iP. Energy utilization did not differ for barrows fed the diets containing hulled or hull-less LPB when ME/kg was equalized with lard. In conclusion, the apparent utilization of P and Ca, the bone strength and fat-free dry weight, and growth performance increased with increasing dietary concentration of aP provided by LPB, in association with linear decreases in P and Ca excretion. Barrows fed the diet containing M955 also had greater utilization and less excretion of P, Ca, N, energy, and DM than barrows fed the diets containing the near-isogenic NB or LPB cultivars with added iP to equalize aP at 0.30%.
选用45头平均初始体重9.5 kg、年龄35日龄的杂交公猪进行了一项为期28天的试验，以评估低植酸大麦（LPB）突变体M422、M635和M955，它们是正常大麦（NB）哈林顿的去壳近等基因后代，植酸含量分别比NB低47%、66%和80%。还评估了一种与其他品种无近等基因关系的裸粒LPB，即M422-H。评估的反应标准包括表观养分平衡、骨骼测量和生长性能。公猪在个体代谢笼中以粉料形式随意采食日粮。大麦和豆粕是植酸的唯一来源。所有日粮中的蛋白质补充量和每千克代谢能（ME）均保持一致。处理方式为日粮中分别含有NB、M422、M635或M422-H，添加或不添加无机磷（iP），以及不添加iP的M955。添加iP的日粮含有0.30%的有效磷（aP），与不添加iP的含M955日粮提供的aP浓度相同。随着不添加iP的近等基因品种NB、M422、M635或M955日粮中aP浓度的增加，平均日增重（ADG）、料重比（G:F）、掌骨和桡骨强度以及无脂干重呈线性增加（P≤0.02），磷和钙的吸收及保留量（克/天和摄入量的百分比）也呈线性增加。随着不添加iP日粮中aP浓度的增加，每天排泄的磷和钙的克数（P≤0.02）和百分比（P<0.001）呈线性下降。氮或能量平衡无反应。饲喂含M955日粮的公猪与饲喂添加iP的含NB、M422或M635近等基因日粮的公猪相比，生长性能和骨骼反应标准无差异。然而，饲喂含M955日粮的公猪的磷、氮和能量吸收及保留百分比、钙吸收、干物质消化率更高（P≤0.02），每天磷、氮、能量和钙的排泄量（克和百分比）更低（P≤0.02）。当通过iP使日粮aP相等时，与饲喂含NB+iP日粮的公猪相比，饲喂含M422+iP、M635+iP或M955日粮的公猪粪便加尿液中磷的排泄量（克/天）分别降低了20.2%、27.9%和44.6%。当每千克ME与猪油相等时，饲喂含去壳或裸粒LPB日粮的公猪能量利用率无差异。总之，随着LPB提供的日粮aP浓度增加，磷和钙的表观利用率、骨骼强度和无脂干重以及生长性能增加，同时磷和钙排泄量呈线性下降。与饲喂添加iP以使aP达到0.30%的近等基因NB或LPB品种日粮的公猪相比，饲喂含M955日粮的公猪对磷、钙、氮、能量和干物质的利用率更高，排泄量更低。
