玉米豆粕型日粮总钙和标准全肠道可消化磷水平对生长猪钙磷沉积和排放的影响

　　本试验研究了玉米豆粕型日粮中总钙和标准全肠道可消化磷（STTD P）水平对生长猪钙磷沉积和排放的影响。将48头杂交阉公猪（初始重22.7±2.9kg）分为8组，在圈舍中适应3周后转移至代谢笼中，前4天为适应期，后5天收集粪样和尿样。配制8种玉米豆粕型试验日粮，净能、脂肪和氨基酸组成相似，只是用磷酸二氢钙将日粮STTD磷含量从0.16%调节到最高至0.62%，保持钙/STTD磷为2.2:1。STTD磷摄入量从猪需要量（4.59g/d）的64%线性增加至242%（P＜0.001）。粪中钙磷含量和总排放量随日粮钙磷摄入量的增加而线性提高（P＜0.001）。尿磷排放量比较稳定（约0.03g/d），但是在4.96g/d STTD磷摄入量组，尿磷的排放量显著增加（P＜0.001）。与此相反，尿中钙排放量随摄入量的增加而减少（P＜0.001），但排放量在摄入量达到17.97g/d时趋于稳定（0.40g/d）。通过STTD磷和钙摄入量预测尿磷和尿钙排放量的的准确度一般（R2分别为0.41和0.62）。磷吸收量和沉积量随磷摄入量的增加而线性提高（P＜0.001），而钙的吸收和沉积却随摄入量的增加而呈二次线性关系（P＜0.001）。钙磷的吸收和沉积与STTD磷和钙的摄入量密切相关，R2分别为0.90和0.87。随STTD磷摄入量的提高，大腿骨矿物质含量（FMC）增加2.71g，但是在STTD磷摄入量到达8.84g/d时大腿骨矿物质含量达到平衡（29.54g）。大腿骨矿物质含量可以被STTD磷摄入量精确预测（R2=0.89）。大腿骨矿物质含量可以影响尿磷排放（P＜0.01），但是不是主要原因（R2=0.19）。总之，尿磷排放量比较稳定，但在STTD磷摄入量超过生长需要时，排放量也会增加。大腿骨矿物质含量随着STTD磷含量的增加而增加，但是在STTD磷摄入量超过生长需要时也会进入平台期。日粮STTD磷被用于生长需要并在骨骼中沉积，当到超过需要量后，多余的磷会在尿中排出。由日粮STTD磷和钙摄入量预测钙磷排放量的预测效果一般。

　　Effects of high-protein or conventional canola meal on growth performance, organ weights, bone ash, and blood characteristics of weanling pigs

　　C. K. Parr, Y. Liu, C. M. Parsons and H. H. Stein

　　An experiment was conducted to evaluate effects of 2 high-protein canola meals (canola meal A [CMA]: 45.69% CP and canola meal B [CMB]: 46.97% CP) and a conventional canola meal (CM-CV: 35.10% CP) on growth performance, organ weights, bone ash, and blood parameters of weanling pigs. Inclusion rates of canola meal (CM) in the diets were 10, 20, 30, or 40% for CMA and CM-CV, whereas inclusions were 10, 20, or 30% for CMB. A control diet containing no CM was also formulated. Therefore, 12 diets were used in this experiment. A total of 420 pigs (initial BW: 9.8 ± 1.1 kg) were divided into 3 blocks and randomly allotted to 1 of the 12 diets with 8 replicate pens per treatment and 4 or 5 pigs per pen. The ADG, ADFI, and G:F were calculated, and at the conclusion of the experiment, 1 pig in each pen was euthanized to allow measurements of organ weights, collection of blood, and collection of the third and fourth metacarpals from the left foot. Results indicate that ADFI was linearly (P < 0.05) decreased if inclusion of CMA, CMB, or CM-CV was increased. Average daily gain for pigs fed CMA tended to increase quadratically with the maximum response observed at 10 or 20% CM inclusion in the diet (P = 0.06). However, G:F was linearly (P < 0.05) increased by adding CMA or CM-CV to the diets. Liver weights were also linearly (P < 0.05) increased if pigs were fed diets containing CMB, but kidney weights were linearly (P < 0.05) decreased by the addition of CM-CV to the diets. Thyroid gland weights increased linearly (P < 0.05) for pigs fed diets containing CMA. No differences were observed in heart and bone weights if CM was added to the diets. Addition of any of the 3 CM linearly (P < 0.05) increased bone ash percentage in the metacarpals. Inclusion of CMA or CM-CV linearly (P < 0.05) decreased concentrations of serum triiodothyronine, and the inclusion of CMA also linearly (P < 0.05) decreased serum thyroxine concentrations. No differences were observed for complete blood counts or blood urea nitrogen if CM was added to the diets. In conclusion, up to 20% high-protein CM or CM-CV may be included in diets for weanling pigs from 2 wk postweaning without reducing growth performance or negatively affecting organ, bone, or blood parameters. In some instances, it may also be possible to use greater inclusion rates.

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