玉米豆粕型日糧總鈣和標準全腸道可消化磷水平對生長豬鈣磷沉積和排放的影響

　　本試驗研究了玉米豆粕型日糧中總鈣和標準全腸道可消化磷（STTD P）水平對生長豬鈣磷沉積和排放的影響。將48頭雜交閹公豬（初始重22.7±2.9kg）分為8組，在圈舍中適應3周后轉移至代謝籠中，前4天為適應期，后5天收集糞樣和尿樣。配制8種玉米豆粕型試驗日糧，凈能、脂肪和氨基酸組成相似，只是用磷酸二氫鈣將日糧STTD磷含量從0.16%調節到最高至0.62%，保持鈣/STTD磷為2.2:1。STTD磷攝入量從豬需要量（4.59g/d）的64%線性增加至242%（P＜0.001）。糞中鈣磷含量和總排放量隨日糧鈣磷攝入量的增加而線性提高（P＜0.001）。尿磷排放量比較穩定（約0.03g/d），但是在4.96g/d STTD磷攝入量組，尿磷的排放量顯著增加（P＜0.001）。與此相反，尿中鈣排放量隨攝入量的增加而減少（P＜0.001），但排放量在攝入量達到17.97g/d時趨于穩定（0.40g/d）。通過STTD磷和鈣攝入量預測尿磷和尿鈣排放量的的準確度一般（R2分別為0.41和0.62）。磷吸收量和沉積量隨磷攝入量的增加而線性提高（P＜0.001），而鈣的吸收和沉積卻隨攝入量的增加而呈二次線性關系（P＜0.001）。鈣磷的吸收和沉積與STTD磷和鈣的攝入量密切相關，R2分別為0.90和0.87。隨STTD磷攝入量的提高，大腿骨礦物質含量（FMC）增加2.71g，但是在STTD磷攝入量到達8.84g/d時大腿骨礦物質含量達到平衡（29.54g）。大腿骨礦物質含量可以被STTD磷攝入量精確預測（R2=0.89）。大腿骨礦物質含量可以影響尿磷排放（P＜0.01），但是不是主要原因（R2=0.19）。總之，尿磷排放量比較穩定，但在STTD磷攝入量超過生長需要時，排放量也會增加。大腿骨礦物質含量隨著STTD磷含量的增加而增加，但是在STTD磷攝入量超過生長需要時也會進入平臺期。日糧STTD磷被用于生長需要并在骨骼中沉積，當到超過需要量后，多余的磷會在尿中排出。由日糧STTD磷和鈣攝入量預測鈣磷排放量的預測效果一般。

　　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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