2017. J. Anim. Sci. 95(10): 4499-4509

　　A. Craig, A. Gordon and E. Magowan

　　現(xiàn)代母豬在哺乳期采食量較低。本試驗(yàn)的主要目的在于研究采食量和營養(yǎng)濃度對斷奶重的影響及其互作。同時也研究了一些關(guān)鍵因素，比如說初乳攝入量、仔豬存活、斷奶重和初乳產(chǎn)量。82頭母豬分為4組，2（日糧濃度）×2（采食量）雙因素試驗(yàn)設(shè)計(jì)。高日糧濃度為15.8MJ/kg消化能、1.3%總賴氨酸；低日糧濃度為15.2 MJ/kg消化能、1.2%總賴氨酸。高采食量為：分娩后飼喂量每天增加0.5kg，直到采食量達(dá)到10kg/d；低采食量為分娩后飼喂量每天增加0.3kg，直到采食量達(dá)到7.5kg/d。收集18頭分娩母豬的數(shù)據(jù)，分析影響初乳攝入量的因素。試驗(yàn)結(jié)果表明日糧濃度和飼喂水平之間沒有互作。低飼喂水平母豬在哺乳期間的失重較高飼喂水平母豬多10.6kg（P＜0.001）。飼喂高營養(yǎng)日糧母豬失重比低營養(yǎng)日糧組多6.4kg（P = 0.018）。日糧營養(yǎng)濃度對采食量無影響。哺乳期間，與低采食量組相比，高采食量組母豬的仔豬窩增重高326g/d（P＜0.001），并且母豬斷奶時體重更大（114kg VS. 104kg，P＜0.001）。盡管高營養(yǎng)濃度組斷奶窩重與低營養(yǎng)濃度組相似，但是高營養(yǎng)濃度組窩日增重高190g/d（P=0.018）。192頭母豬數(shù)據(jù)的回歸分析結(jié)果表明斷奶窩重的主要影響因素是哺乳期采食量、賴氨酸攝入量和哺乳第14-28天的消化能和賴氨酸攝入量。哺乳第0-7天哺乳效率為0.65，然后在第21-28天降低至0.42。初乳攝入量主要影響因素為24h體重、初生重、分娩時間。初乳產(chǎn)量與出生窩重顯著相關(guān)（P=0.004，pseudo R2 = 54.5%）。仔豬斷奶重與3周齡體重顯著正相關(guān)（P＜0.001），但是與母豬胎次（P=0.035）、出生活仔數(shù)（P=0.045）、雌豬（P＜0.001）顯著負(fù)相關(guān)。在45個指標(biāo)中，仔豬斷奶前存活率只與出生24h-48增重有關(guān)正相關(guān)（P=0.008）。總之，哺乳后半期采食量、消化能攝入量和賴氨酸攝入量是斷奶窩重的主要影響因素。

　　Understanding the drivers of improved pig weaning weight by investigation of colostrum intake, sow lactation feed intake, or lactation diet specification

　　A. Craig, A. Gordon and E. Magowan

　　Modern sows have low feed intake (FI) during lactation. The main aim of this study was to understand interactions between and separate effects of FI and nutrient density on litter weaning weight (WW). Key drivers of colostrum intake (CIn), piglet survival, WW, and colostrum yield (CY) were also investigated. Sows (n = 82) were offered a High (15.8 MJ/kg DE; 1.3% total lysine) or Normal (15.2 MJ/kg DE; 1.28% totallysine) specification lactation diet at either a High (feed allowance increased by 0.5 kg/d after farrowing until intake reached 10 kg/d) or Low (feed allowance was increased by 0.3 kg/d after farrowing until intake reached 7.5 kg/d) feeding level (2 × 2 factorial design). A subset of sows (n = 18) were observed during farrowing to collect data on factors affecting CIn. No interactions were found between diet specification and feeding level. Sows on the Low feeding level lost 10.6 kg more BW during lactation than those on the High feeding level (P < 0.001). Sows offered the High specification diet lost 6.4 kg more BW than those on the Normal specification diet (P = 0.018). Diet specification had no effect on ADFI. Between birth and weaning, litters of sows offered the High feeding level grew 326 g/d faster (P < 0.001) and were heavier at 28 d(114 kg; P < 0.001) compared with those of sows offered the Low feeding level (104 kg). Although litters from sows offered the High specification diet had WW similar to that of litters from sows offered the Normal specification diets, their ADG was 190 g/d greater (P = 0.018) between birth and weaning. A regression analysis was completed using data from 192 sows and indicated that FI and lysine intake throughout lactation and DE and lysine intake from 14 to 28 d of lactation were the main drivers of litter WW. Lactation efficiency was 0.65 from 0 to 7 d and decreased to 0.42 from 21 to 28 d. Variation in CIn was mainly explained by 24-h weight, birth weight, and the duration of farrowing. Colostrum yield was significantly correlated (P = 0.004; pseudo R2 = 54.5%) with litter birth weight. Piglet WW was positively correlated with 3-wk weight (P < 0.001) but negatively correlated with sow parity (P = 0.035), number born alive (P = 0.045), and being female (P < 0001). Out of 45 variables, preweaning piglet survival was positively correlated (P = 0.008) with only 24- to 48-h weight gain. In conclusion, lactation FI and DE and lysine intake in the second half of lactation were the main drivers of litter WW.