Pig Improvement Company, Hendersonville, TN 37075, USA.
J Anim Sci. 2010 Jul;88(7):2265-76. doi: 10.2527/jas.2009-2121. Epub 2010 Feb 26.
A total of 1,034 pigs produced by breeding PIC sows to 2 different PIC terminal sires were used to create 3 distinct weaning weight populations so that postweaning growth to 125 kg could be studied. The rearing strategies resulted in BW that ranged from 4.1 to 11.5 kg by 20 d of age. Sows and corresponding litters were allocated to 3 treatments: sow reared (SR; n = 367) for 20 d, sow reared for 14 d (14W; n = 330), and sow reared for 2 d (2W; n = 337). Sows were removed from 2W and 14W groups, but progeny remained in the crates and received milk replacer ad libitum (for 18 and 6 d, respectively) until the contemporary SR pigs were weaned at 20 d of age. The SR pigs (6.49 +/- 0.15 kg) weighed 1.01 kg less than 14W pigs (7.5 +/- 0.14 kg) and 2.26 kg less than 2W pigs (8.75 +/- 0.14 kg; P < 0.05). The 14W pigs weighed 1.25 kg less than 2W pigs (P < 0.05). Nursery ADG for the 2W group (547 g/d) was 35 g/d less (P < 0.05) than 14W pigs. The 14W pigs (165 d) required 3 fewer (P < 0.05) days to reach 125 kg of BW compared with SR pigs. The SR and 14W pigs gained BW 24 and 20 g/d faster (P < 0.05) in the postnursery period when compared with 2W pigs. The SR and 2W pigs consumed 0.10 and 0.12 kg/d less (P < 0.05) during this period when compared with 14W pigs (2.32 kg/d). Gain:feed of SR was improved (P < 0.05) when compared with the 14W and 2W pigs over 167 d of age (0.44 vs. 0.42 and 0.42, respectively). Lean percentage was 0.7% greater (P < 0.05) in carcasses from SR pigs (55.0%) compared with carcasses from 2W pigs (54.3%) when adjusted to a constant HCW. A study of the effect of weaning weight on days to 125 kg was limited to SR and 14W groups because maternal deprivation compromised the 2W group postweaning growth. Six weaning-weight groups were defined using a normal distribution: 4.6, 5.5, 6.4, 7.3, 8.2, and 9.5 kg. Pigs weighing 5.5 kg at 20 d of age were able to reach 125 kg 8 d sooner (168.8 d) than those weighing 4.6 kg (176.8 d). There was a linear relationship (P < 0.05) between weaning weight and ADG in the postnursery phase of growth. We conclude that 1) a weaning weight of less than 5.0 kg imposes the greatest marginal loss in production output for a 20-d weaning and 2) lactation length influences long-term growth, composition of growth, and viability of progeny.
共有 1034 头由 PIC 母猪与 2 头不同的 PIC 终端公猪交配所产的仔猪用于创建 3 个不同的断奶体重群体，以便研究断奶后至 125kg 的生长情况。饲养策略导致 20 日龄体重范围为 4.1-11.5kg。母猪和相应的仔猪被分配到 3 种处理方法：母猪饲养（SR；n=367）20 天、母猪饲养 14 天（14W；n=330）和母猪饲养 2 天（2W；n=337）。2W 和 14W 组的母猪被移除，但仔猪仍留在笼子里并自由饮用代乳料（分别为 18 和 6 天），直到同期 SR 仔猪在 20 日龄断奶。SR 仔猪（6.49+/-0.15kg）比 14W 仔猪（7.5+/-0.14kg）轻 1.01kg，比 2W 仔猪（8.75+/-0.14kg）轻 2.26kg（P<0.05）。14W 仔猪比 2W 仔猪轻 1.25kg（P<0.05）。2W 组的育肥猪 ADG（547g/d）比 14W 仔猪低 35g/d（P<0.05）。14W 仔猪（165d）比 SR 仔猪提前 3 天（P<0.05）达到 125kg 的体重。与 2W 仔猪相比，SR 和 14W 仔猪在断奶后阶段体重增加 24 和 20g/d 更快（P<0.05）。与 14W 仔猪相比，SR 和 2W 仔猪在这段时间内分别消耗 0.10 和 0.12kg/d 的饲料更少（P<0.05）（2.32kg/d）。SR 仔猪的生长：饲料比（14W 和 2W 仔猪分别为 0.44 和 0.42）在 167 日龄以上时得到改善（P<0.05）。与 2W 仔猪相比，SR 仔猪的胴体瘦肉率高 0.7%（P<0.05）（55.0%对 54.3%），当调整到恒重时。由于母源剥夺影响了 2W 组断奶后的生长，因此限制了 2W 组断奶后体重对达到 125kg 天数的影响研究仅限于 SR 和 14W 组。使用正态分布定义了 6 个断奶体重组：4.6、5.5、6.4、7.3、8.2 和 9.5kg。20 日龄体重为 5.5kg 的仔猪比体重为 4.6kg 的仔猪提前 8 天（168.8d）达到 125kg（176.8d）。断奶后阶段的生长中存在线性关系（P<0.05）。我们得出结论：1）断奶体重低于 5.0kg 会对 20 天断奶的生产输出造成最大的边际损失；2）哺乳期长度影响长期生长、生长组成和后代的活力。
