1 Nutreco Research and Development, P.O. Box 220, 5830 AE, Boxmeer, the Netherlands.
2 Wageningen UR Livestock Research, P.O. Box 65, 8200 AB, Lelystad, the Netherlands.
Animal. 2014 Jun;8(6):923-30. doi: 10.1017/S175173111400069X. Epub 2014 Mar 28.
The evolution of hyper-prolific pig breeds has led to a higher within-litter variation in birth weight and in BW gain during the nursery phase. Based on an algorithm developed in previous research, two populations from a pool of 368 clinically healthy piglets at 6 weeks of age were selected: a low (LP) and a high (HP) performing population and their development was monitored until the end of the nursery phase (10 weeks of age). To understand the cause of the variation in growth between these populations we characterized the LP and HP piglets in terms of body morphology, behaviour, voluntary feed intake, BW gain, and apparent total tract and ileal nutrient digestibility. Piglets were housed individually and were fed a highly digestible diet. At selection, 6 weeks of age, the BW of LP and HP piglets were 6.8±0.1 and 12.2±0.1 kg, respectively. Compared with the LP piglets the HP piglets grew faster (203 g/day), ate more (275 g/day) from 6 to 10 weeks of age and were heavier at 10 weeks (30.0 v. 18.8 kg, all P<0.01). Yet, the differences in average daily gain and average daily feed intake disappeared when compared per kg BW0.75. Assuming similar maintenance requirements per kg BW0.75 the efficiency of feed utilization above maintenance was 0.1 g/g lower for the LP piglets (P=0.09).The gain : feed ratio was similar for both groups. LP piglets tended to take more time to touch a novel object (P=0.10), and spent more time eating (P<0.05). At 10 weeks, LP piglets had a higher body length and head circumference relative to BW (P<0.01). Relative to BW, LP had a 21% higher small intestine weight; 36% longer length, and relative to average FI, the small intestinal weight was 4 g/kg higher (both P=<0.01). Apparent total tract and ileal dry matter, N and gross energy digestibility were similar between groups (P>0.10). We concluded that the low performance of the LP piglets was due to their inability to engage compensatory gain or compensatory feed intake as efficiency of nutrient utilization and feed intake per kg BW0.75 was unaffected. LP piglets tend to be more fearful towards novel objects. The morphological comparisons, increased body length and head circumference relative to BW imply that LP piglets have an increased priority for skeletal growth.
高繁殖力猪种的进化导致产仔数和仔猪哺乳期体重增加存在更高的个体间差异。基于之前研究中开发的算法，从 6 周龄的 368 头临床健康仔猪中选择了两个群体：一个低（LP）表现群体和一个高（HP）表现群体，并对其进行监测，直至哺乳期结束（10 周龄）。为了了解这些群体之间生长差异的原因，我们根据体型、行为、自由采食量、体重增加、表观全肠道和回肠养分消化率对 LP 和 HP 仔猪进行了特征描述。仔猪单独饲养，喂食高消化率日粮。在选择时，即 6 周龄，LP 和 HP 仔猪的体重分别为 6.8±0.1kg 和 12.2±0.1kg。与 LP 仔猪相比，HP 仔猪生长更快（203g/天），6-10 周龄时采食量更高（275g/天），10 周龄时体重更重（30.0v.18.8kg，均 P<0.01）。然而，当按每公斤 BW0.75 比较平均日增重和平均日采食量时，差异消失。假设每公斤 BW0.75 的维持需要相同，那么 LP 仔猪的饲料利用效率比维持效率低 0.1g/g（P=0.09）。两组的增重：饲料比相似。LP 仔猪接触新物体的时间往往更长（P=0.10），且进食时间更长（P<0.05）。10 周龄时，LP 仔猪的体重与 BW 相比，体长和头围更高（P<0.01）。与 BW 相比，LP 仔猪的小肠重量高 21%；长度长 36%；与平均 FI 相比，小肠重量高 4g/kg（均 P<0.01）。两组的全肠道和回肠干物质、N 和总能消化率相似（P>0.10）。我们得出结论，LP 仔猪表现不佳是因为它们无法进行补偿性生长或补偿性采食量，因为养分利用效率和每公斤 BW0.75 的采食量不受影响。LP 仔猪对新物体往往更恐惧。与 BW 相比，体长和头围的增加意味着 LP 仔猪的骨骼生长优先级更高。
