Sows mated in summer produce a greater proportion of born-light piglets (<1.1 kg) which contributes to increased carcass fatness in the progeny population. The reasons for the low birth weight of these piglets remain unclear, and there have been few successful mitigation strategies identified. We hypothesized that: 1) the low birth weight of progeny born to sows mated in summer may be associated with weight loss during the previous summer lactation; and 2) increasing early gestation feed allowance for the sows with high lactational weight loss in summer can help weight recovery and improve progeny birth weight. Sows were classified as having either low (av. 1%) or high (av. 7%) lactational weight loss in their summer lactation. All the sows with low lactational weight loss (LLStd) and half of the sows with high lactational weight loss received a standard gestation feeding regime (HLStd) (2.6 kg/d; day 0–30 gestation), whereas the rest of the sows with high lactational weight loss received a compensatory feed allowance (HLComp) (3.5 kg/d; day 0–30 gestation). A comparison of LLStd (n = 75) versus HLStd sows (n = 78) showed that this magnitude of weight loss over summer lactation did not affect the average piglet or litter birth weight, but such results may be influenced by the higher litter size (P = 0.030) observed in LLStd sows. A comparison of HLStd versus HLComp (n = 81) sows showed that the compensatory feeding increased (P = 0.021) weight gain of gestating sows by 6 kg, increased (P = 0.009) average piglet birth weight by 0.12 kg, tended to reduce (P = 0.054) the percentage of born-light piglets from 23.5% to 17.1% but reduced the litter size by 1.4 (P = 0.014). A subgroup of progeny stratified as born-light (0.8–1.1 kg) or -normal (1.3–1.7 kg) from each sow treatment were monitored for growth performance from weaning until 100 kg weight. The growth performance and carcass backfat of progeny were not affected by sow treatments. Born-light progeny had lower feed intake, lower growth rate, higher G:F, and higher carcass backfat than born-normal progeny (all P < 0.05). In summary, compensatory feeding from day 0 to 30 gestation in the sows with high weight loss during summer lactation reduced the percentage of born-light progeny at the cost of a lower litter size, which should improve growth rate and carcass leanness in the progeny population born to sows with high lactational weight loss.

中文翻译：

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夏季泌乳后体重减轻较多的母猪在妊娠早期进行代饲可增加仔猪出生体重，但会减少产仔数

夏季交配的母猪产下的体重较轻的仔猪比例更高（<1.1 kg），这有助于增加后代群体的胴体脂肪。这些仔猪低出生体重的原因仍不清楚，并且几乎没有确定成功的缓解策略。我们假设：1）夏季交配的母猪所产后代的低出生体重可能与前一个夏季哺乳期的体重减轻有关；2) 增加夏季泌乳期体重减轻率高的母猪妊娠早期饲喂量有助于恢复体重，提高后代出生体重。母猪在夏季泌乳期间被分为低（平均 1%）或高（平均 7%）泌乳期体重减轻。所有具有低泌乳期体重减轻 (LLStd) 的母猪和一半具有高泌乳期体重减轻的母猪接受标准妊娠饲喂方案 (HLStd)（2.6 kg/d；妊娠 0-30 天），而其余高泌乳期体重减轻获得了补偿性饲料津贴 (HLComp)（3.5 kg/d；妊娠 0-30 天）。LLStd (n = 75) 与 HLStd 母猪 (n = 78) 的比较表明，夏季泌乳期间体重减轻的幅度不会影响平均仔猪或窝出生体重，但这种结果可能受到较高窝产仔数的影响。 P = 0.030) 在 LLStd 母猪中观察到。HLStd 与 HLComp（n = 81）母猪的比较表明，补饲使妊娠母猪增重（P = 0.021）增加 6 kg，平均仔猪出生体重增加（P = 0.009）0.12 kg，趋于减少（P = 0.009）。 P = 0。054) 轻生仔猪的百分比从 23.5% 降低到 17.1%，但窝产仔数减少了 1.4 (P = 0.014)。从断奶到体重 100 公斤，监测每个母猪处理后的子代亚组的生长性能，这些子代分为出生轻（0.8-1.1 公斤）或正常（1.3-1.7 公斤）。后代的生长性能和胴体背膘不受母猪处理的影响。与出生正常的后代相比，初生的后代采食量较低，生长速率较低，G:F 较高，胴体背膘脂肪较高（所有 P < 0.05）。总之，夏季泌乳期间体重减轻较多的母猪在妊娠第 0 天到第 30 天进行补饲，以较低的窝产仔数为代价降低了轻产后代的百分比，这应该会提高后代群体的生长速度和胴体瘦肉率产于哺乳期体重减轻率高的母猪。