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本試驗的目的在于研究商業條件下不同標準回腸可消化賴氨酸（SID賴氨酸）和代謝能水平對后備母豬生長發育的影響。試驗對照組日糧SID賴氨酸和代謝能來源于對美國養豬行業的調查和投票。1221頭大白×長白二元母豬隨機分為6組，試驗采用2×3因子設計，2個SID賴氨酸水平、3個代謝能水平。母豬為群體飼養，日糧為玉米-豆粕型日糧。后備母豬生長期日糧SID賴氨酸水平包括1.02%（對照組，為調查平均值）、0.86%（比對照組水平降低15%），代謝能水平2.94、3.25、3.57 Mcal/kg（平均值上下10%），飼喂期為100日齡至約90kg體重。育肥期日糧中SID賴氨酸水平為0.85%（對照組，為調查平均值）、0.73%（比對照組水平降低15%），代謝能水平為2.94、3.26、3.59 Mcal/kg（平均值上下10%），飼喂至260日齡。試驗開始、及每28天測定后備母豬體重、背膘厚和眼肌面積。后備母豬160日齡開始接觸切除輸精管的公豬，并觀察發情狀況。在約260日齡時，將后備母豬屠宰，收集生殖系統樣品。每個樣品檢查測定是否處于發情期、發情期的哪個階段、排卵數和子宮長度。所有數據使用正態分布和混合模型進行統計分析。初情期在160-265日齡，平均日齡為193天。若以靜立反射為發情標準，試驗中160日齡后備母豬有91.0%已經開始發情。日糧處理對初情期日齡和生殖系統的影響不顯著。在公豬從160日齡開始刺激母豬的情況下，后備母豬100-160日齡的生長速度不會影響母豬初情時的日齡。

The objective of this study was to determine the effect of ad libitum feeding diets differing in standard ileal digestible (SID) lysine and ME concentrations that bracket those fed to developing gilts in U.S. commercial settings. Average SID lysine and ME concentrations in diets currently fed to developing gilts were obtained from a poll of the U.S. commercial swine industry. Crossbred Large White × Landrace gilts (n = 1,221), housed in groups, were randomly allotted to 6 corn-soybean diets in a 2 × 3 factorial arrangement formulated to provided 2 SID lysine and 3 ME concentrations. Gilts received grower diets formulated to provide 1.02%(control = survey average) or 0.86% (control minus 15%) SID lysine and 2.94, 3.25, or 3.57 (survey average ME ± 10%) Mcal of ME/kg from 100 d of age until approximately 90 kg BW. Then, gilts were fed finisher diet containing 0.85%(control = survey average) or 0.73% (control minus 15%) SID lysine and 2.94, 3.26, or 3.59 (control ± 10%) Mcal of ME/kg until 260 d of age. Gilts were weighed, and backfat thickness and loin muscle area were recorded at the beginning of the trial and then every 28 d. Starting at 160 d of age, gilts were exposed daily to vasectomized boars and observed for behavioral estrus. At approximately 260 d of age, gilts were slaughtered and their reproductive tract was collected. Each reproductive tract was examined to determine whether the gilt was cyclic, the stage of estrus cycle, ovulation rate, and uterine length.Data were evaluated for normality and analyzed using mixed model methods. Average age at puberty was 193 d of age with a range from 160 to 265 d. When all gilts on trial at 160 d of age were included in the analysis, 91.0% reached puberty as determine by observation of standing estrus. Differences between dietary treatments on age at puberty or measurements of the reproductive tract were not detected. Growth rates to 160 d were not limiting for attainment ofpuberty in response to daily boar stimulation from 160 d.

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