This study aimed to investigate the effectiveness of employing a targeted nutritional regime until slaughter to maintain performance in animals recording high weaning weights. Low birthweight (Low BW; <1 kg) and average birthweight (Av BW; 1.3kg-1.7 kg) pigs were reared on sows exhibiting a high lactation feed intake and, as a result, weaning weights were 7.9 kg and 8.9 kg respectively. Pens containing either Low BW or Av BW animals were then offered either a ‘standard’ (STAND) or ‘feed-to-weight’ (FTW) regime from weaning until slaughter. The STAND regime was reflective of commercial production, where diet transitions were implemented after pre-determined feed levels or time intervals had been reached. In contrast, diet transitions in the FTW regime were carried out when target pen average weights of 12 kg, 18 kg, 22 kg, 45 kg and 75 kg respectively were met. Animal growth, feeding performance and body composition were monitored from weaning until slaughter. As expected, Av BW pigs were heavier than Low BW animals throughout (P<0.001), recording a superior average daily gain (ADG) (P<0.01) and average daily feed intake (ADFI) (P<0.001) at each stage of growth. This resulted in Av BW animals recording a greater carcass weight (P<0.001) and kill-out percentage (P<0.01). DEXA scan analysis showed Low BW animals to exhibit a greater percentage fat (P<0.001) and lower percentage lean (P<0.01) content at week 4 and 10 of age, however birthweight had no effect on these parameters at week 21 (P>0.05). Feeding regime did not affect age or weight at diet transition for Av BW animals for most transitions (P>0.05). However Low BW animals offered the FTW regime were significantly older and heavier than those offered the STAND regime at each transition (P<0.05). The FTW regime increased animal ADG and ADFI compared to STAND pigs from weeks 4 to 10 of age (P<0.05), whilst providing a greater average daily intake of energy and lysine from week 4 to 10 (P<0.05) and week 10 to 17 (P<0.05). This facilitated a greater liveweight in FTW animals from 7 weeks of age through to slaughter (P<0.05). Feeding regime had no effect on kill-out percentage or back-fat depth (P>0.05). Furthermore, DEXA scan results showed total or percentage lean and fat did not differ for FTW or STAND pigs at 10 or 21 weeks of age (P>0.05). In conclusion, feeding Low BW animals on a ‘feed to weight’ basis improved nutrient intake and animal liveweight, likely due to a greater time allowance for digestive development between diet transitions. As such, this approach should be considered for commercial adoption.

这项研究旨在调查采用有针对性的营养方案直至屠宰以保持高断奶体重的动物的生产性能。将低出生体重（低体重； <1公斤）和平均出生体重（平均体重； 1.3kg-1.7公斤）的猪饲养在泌乳量高的母猪上，结果断奶体重分别为7.9公斤和8.9公斤。包含低BW或Av的笔然后，从断奶到宰杀，给体重动物提供“标准”（标准）或“体重加重”（FTW）方案。STAND制度反映了商业化生产，在达到预定的饲料水平或时间间隔后实施了饮食过渡。相比之下，FTW方案中的饮食过渡是在分别达到12公斤，18公斤，22公斤，45公斤和75公斤的平均目标体重时进行的。从断奶到宰杀期间监测动物的生长，饲养性能和身体组成。正如预期的那样，Av BW猪在整个过程中都比低BW猪重（P <0.001），记录的平均日增重（ADG）（P <0.01）和平均日采食量（ADFI）均较高（P<0.001）。这导致Av BW动物记录了更大的car体重量（P <0.001）和淘汰率（P <0.01）。DEXA扫描分析显示，低体重动物在4周和10周龄时脂肪比例更高（P <0.001）和瘦肉比例更低（P <0.01），但是出生体重在21周时对这些参数没有影响（P > 0.05）。对于大多数过渡期，Av BW动物的饮食过渡期的喂养方式均不影响其年龄或体重（P > 0.05）。但是，在每次过渡时，采用FTW方案的低体重动物明显比提供STAND方案的动物年长且重（P<0.05）。与STAND猪相比，从第4周到第10周，FTW方案增加了动物的ADG和ADFI（P <0.05），而从第4周到10周（P <0.05）和从第10周到第10周，提供了更高的平均每日能量和赖氨酸摄入量。17（P <0.05）。从7周龄到屠宰，这促进了FTW动物的活重（P <0.05）。喂养方式对杀灭率或后脂肪深度没有影响（P > 0.05）。此外，DEXA扫描结果显示，10或21周龄的FTW或STAND猪的瘦肉和脂肪的总含量或百分比没有差异（P> 0.05）。总之，以“按体重饲料”喂养低体重的动物可以改善营养摄入和动物活重，这可能是由于在饮食过渡之间有更多的消化发育时间所致。因此，应考虑将此方法用于商业用途。