Becker Spenser L, Gould Stacie A, Petry Amy L, Kellesvig Leah M, Patience John F
Department of Animal Science, Iowa State University, Ames, IA.
Iowa Pork Industry Center, Iowa State University, Ames, Iowa.
J Anim Sci. 2020 Oct 1;98(10). doi: 10.1093/jas/skaa325.
The objective of this experiment was to evaluate the growth performance and bone mineral content (BMC) of nursery pigs in response to increasing total calcium (Ca) to available phosphorus (aP) ratios in diets containing phytase (250 FTU/kg; Natuphos E, BASF, Florham Park, NJ). A total of 480 nursery pigs (body weight (BW) = 5.7 ± 0.6 kg) with 10 pigs per pen and 7 pens per treatment (6 pens fed 2.75:1 diet) were allotted to seven treatments consisting of increasing ratios of calcium to available phosphorus (Ca:aP): 1.25, 1.50, 1.75, 2.00, 2.25, 2.50, and 2.75. From day -7 to 0, pigs were fed a common diet. They were then fed the treatment diets during two experimental phases from day 1 to 14 and 15 to 28, respectively. Available P was formulated to 0.33% and 0.27% (approximately 90% of requirement) in dietary phases 1 and 2, respectively. BW, average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F) were determined. BMC of the femur was measured on day 28 on one pig per pen using dual x-ray absorptiometry. Data were analyzed as a linear mixed model using PROC MIXED (SAS, 9.3). Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing the Ca:aP. Over the 28-d experimental period, increasing Ca:aP resulted in a linear decrease in ADG (353, 338, 328, 304, 317, 291, and 280 g/d; P < 0.01), ADFI (539, 528, 528, 500, 533, 512, and 489 g/d; P < 0.05), and G:F (0.68, 0.66, 0.64, 0.62, 0.61, 0.59, and 0.58; P < 0.01). Increasing Ca:aP also resulted in decreased BW on days 14 and 28 (P < 0.01). The BMC of the femur decreased with increasing Ca:aP (6.2, 6.3, 5.7, 5.9, 5.5, 5.6, and 5.3 g; P < 0.05). Regression analysis explained the impact of Ca:aP as follows on ADG (ADG [g/d] = 339 - 36x; r2 = 0.81), G:F (G:F = 0.61 - 0.03x; r2 = 0.72), and BMC (BMC [g] = 6.4 - 0.27x; r2 = 0.43), where x is the Ca:aP. In conclusion, all outcomes indicated that any level of calcium above the minimum used in this experiment impaired growth performance and skeletal development. Further research using even lower levels of dietary Ca is warranted.
本试验旨在评估在含有植酸酶（250 FTU/kg；Natuphos E，巴斯夫公司，新泽西州弗洛勒姆帕克）的日粮中，提高总钙（Ca）与有效磷（aP）的比例对保育猪生长性能和骨矿物质含量（BMC）的影响。总共480头保育猪（体重（BW）= 5.7±0.6 kg），每栏10头猪，每个处理7栏（6栏饲喂Ca:aP比例为2.75:1的日粮），被分配到7个处理组，其钙与有效磷比例（Ca:aP）逐渐增加：1.25、1.50、1.75、2.00、2.25、2.50和2.75。从第-7天到第0天，给猪饲喂普通日粮。然后在两个试验阶段，即从第1天到第14天和第15天到第28天，分别给它们饲喂处理日粮。在日粮的第1阶段和第2阶段，有效磷分别设定为0.33%和0.27%（约为需求量的90%）。测定了体重、平均日增重（ADG）、平均日采食量（ADFI）和料重比（G:F）。在第28天，使用双能X线吸收法对每栏的1头猪测量股骨的BMC。数据采用PROC MIXED（SAS，9.3）进行线性混合模型分析。使用正交多项式对比来确定增加Ca:aP的线性和二次效应。在28天的试验期内，增加Ca:aP导致ADG（分别为353、338、328、304、317、291和280 g/d；P<0.01）、ADFI（分别为539、528、528、500、533、512和489 g/d；P<0.05）和G:F（分别为0.68、0.66、0.64、0.62、0.61、0.59和0.58；P<0.01）呈线性下降。增加Ca:aP还导致在第14天和第28天体重下降（P<0.01）。股骨的BMC随着Ca:aP的增加而降低（分别为6.2、6.3、5.7、5.9、5.5、5.6和5.3 g；P<0.05）。回归分析解释了Ca:aP对ADG（ADG [g/d] = 339 - 36x；r2 = 0.81）、G:F（G:F = 0.61 - 0.03x；r2 = 0.72）和BMC（BMC [g] = 6.4 - 0.27x；r2 = 0.43）的影响，其中x为Ca:aP。总之，所有结果表明，高于本试验中使用的最低钙水平的任何钙水平都会损害生长性能和骨骼发育。有必要使用更低水平的日粮钙进行进一步研究。
