Long C J, Kondratovich L B, Westphalen M F, Stein H H, Felix T L
Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana 61801.
Transl Anim Sci. 2017 Apr 1;1(2):168-178. doi: 10.2527/tas2017.0020. eCollection 2017 Apr.
Objectives were to determine interactions between phytase inclusion and dietary P concentration on P utilization by beef cattle fed a starch-based diet. Six ruminally-fistulated steers (BW = 750 ± 61 kg) were allotted to a 6 × 6 Latin square design with a 3 × 2 factorial arrangement of treatments. Factors included phytase inclusion, at 0, 500, or 2,000 phytase units (FTU)/kg of diet DM, and dietary P concentrations, at 0.10% and 0.30% of total diet DM. Feed ingredients, fecal samples, and orts were composited within period, lyophilized and ground. Samples were analyzed for NDF, ADF, CP, fat, ash, total P, and other minerals. Data were analyzed using the MIXED procedure of SAS with animal as the experimental unit. The CORR procedure was used to compare blood and urinary P concentrations. There were no treatment interactions ( ≥ 0.30) for any parameter measured. There were no main effects ( ≥ 0.45) of phytase inclusion on DMI, total fecal output, apparent DM digestibility, water intake, or urinary output. Steers fed 0.10% P had decreased ( < 0.01) DMI and total fecal output, but increased ( < 0.01) apparent DM digestibility compared with steers fed 0.30% P. Although N intake and retention were not affected by treatment, steers fed the 0.10% P diet tended ( = 0.10) to absorb more N compared with steers fed 0.30% P; and, steers fed the 0.10% P diets excreted more N in the urine ( = 0.02) and less N in the feces ( < 0.01) compared with steers fed the 0.30% P diets. Steers fed the 0.10% P diets also consumed 70.1% less ( < 0.01) total P each day, and excreted 51.9% less ( < 0.01) P in feces and 94.6% less P in the urine ( < 0.01) compared with steers fed 0.30% P. Excretion of water-soluble P in the feces was greater ( < 0.01) on a g/d basis for steers fed 0.30% P when compared with steers fed 0.10% P. However, the proportion of total fecal P excreted as water-soluble P increased ( < 0.05) by 23.0% in steers fed 0.10% P compared with steers fed 0.30% P, regardless of phytase inclusion level. There was no effect of dietary phytase concentration on blood or urinary ( ≥ 0.27) P concentrations. Blood P concentration was positively correlated ( = 0.60; < 0.01) to urinary P concentration when steers were fed 0.10% P; however, when steers were fed 0.30% P, there was no correlation ( = 0.36; = 0.16) between blood and urine P. Regardless of dietary P concentration, phytase supplementation did not increase calculated P absorption or retention.
本研究旨在确定在以淀粉为基础的日粮中添加植酸酶与日粮磷浓度之间对肉牛磷利用率的相互作用。选用6头装有瘤胃瘘管的阉牛（体重=750±61千克），采用6×6拉丁方设计，处理按3×2析因排列。因素包括植酸酶添加量，分别为0、500或2000植酸酶单位（FTU）/千克日粮干物质，以及日粮磷浓度，分别为占日粮总干物质的0.10%和0.30%。在每个时间段内将饲料原料、粪便样本和剩料进行混合，冻干并研磨。分析样本中的中性洗涤纤维、酸性洗涤纤维、粗蛋白、脂肪、灰分、总磷和其他矿物质。数据采用SAS的MIXED程序进行分析，以动物为实验单位。使用CORR程序比较血液和尿液中的磷浓度。所测任何参数均无处理间相互作用（P≥0.30）。植酸酶添加量对干物质采食量、总粪便排出量、表观干物质消化率、饮水量或尿量均无主效应（P≥0.45）。与饲喂0.30%磷日粮的阉牛相比，饲喂0.10%磷日粮的阉牛干物质采食量和总粪便排出量降低（P<0.01），但表观干物质消化率提高（P<0.01）。尽管氮摄入量和潴留量不受处理影响，但与饲喂0.30%磷日粮的阉牛相比，饲喂0.10%磷日粮的阉牛倾向于吸收更多的氮（P=0.10）；并且，与饲喂0.30%磷日粮的阉牛相比，饲喂0.10%磷日粮的阉牛尿液中排出更多的氮（P=0.02），粪便中排出更少的氮（P<0.01）。与饲喂0.30%磷日粮的阉牛相比，饲喂0.10%磷日粮的阉牛每天总磷摄入量也减少70.1%（P<0.01），粪便中磷排出量减少51.9%（P<0.01），尿液中磷排出量减少94.6%（P<0.01）。与饲喂0.10%磷日粮的阉牛相比，饲喂0.30%磷日粮的阉牛粪便中水溶性磷的排出量以克/天计更高（P<0.01）。然而，无论植酸酶添加水平如何，饲喂0.10%磷日粮的阉牛粪便中作为水溶性磷排出的总粪便磷比例比饲喂0.30%磷日粮的阉牛增加了23.0%（P<0.05）。日粮植酸酶浓度对血液或尿液中的磷浓度无影响（P≥0.27）。当阉牛饲喂0.10%磷日粮时，血液磷浓度与尿液磷浓度呈正相关（r=0.60；P<0.01）；然而，当阉牛饲喂0.30%磷日粮时，血液和尿液中的磷之间无相关性（r=0.36；P=0.16）。无论日粮磷浓度如何，添加植酸酶均未提高计算得出的磷吸收率或潴留率。
