Theilgaard P, Baselga M, Blas E, Friggens N C, Cervera C, Pascual J J
1Instituto de Ciencia y Tecnología Animal, Universidad Politécnica de Valencia, Camino de Vera s/n. 46022 Valencia, Spain.
Animal. 2009 May;3(5):637-46. doi: 10.1017/S1751731109003838.
The aim of this work was to evaluate the ability of a line selected for reproductive longevity (LP) to confront productive challenges compared to a line selected during 31 generations for litter size at weaning (V). A total of 133 reproductive rabbit does were used (72 and 61 from LP and V lines, respectively). Within each line, three groups with different levels of productive effort were planned: PP9, inseminated at day 4 after the first partum and with nine kits during the second partum, and inseminated after first weaning (30 days) and with nine (PW9) or five kits (PW5) during the second partum. The reproductive performance, body condition (perirrenal fat thickness (PFT)) and lipolytic response were controlled. LP does showed greater mean live weight (LW; +128 g; P < 0.05), PFT (+0.47 mm; P < 0.05) and estimated body energy (EBE; +0.29 MJ/kg; P < 0.01) than V does at second partum. However, LP does that mated at first post partum did not significantly differ in EBE relative to V does at second partum. During the first week of lactation, dry matter (DM) intake was similar for both lines (94 and 95 g DM/kg LW0.75 day for V and LP does, respectively). There was a significant difference in milk yield between both lines during the first week when litter size was nine (60 v. 54 g of milk/kg LW0.75 day for LP and V does, respectively; P < 0.01), but no difference when litter size was five. Consequently, when litter size was nine, LP does showed a lower recovery of PFT (0.6 mm less; P < 0.05) than V does during the first 10 days of lactation. However, when litter size was five, LP does showed a higher LW (+210 g; P < 0.05) than V does at 10 days of lactation and a similar recovery of PFT. During the last 3 weeks of the lactation, LP does showed a higher feed intake (+6 g DM/kg LW0.75 day; P < 0.05) and milk yield (+27 g/day; P < 0.001) than V does when litter size was nine, resulting in no significant differences in LW at 30 days of lactation. However, when litter size was five, both lines showed similar feed intake and milk yield, maintaining their differences in LW at 30 days of lactation (+206 g for LP does; P < 0.05). These results show that the rabbit line selected for reproductive longevity is more robust with respect to coping with productive challenges, than a line selected for reproductive intensity.
本研究旨在评估一个经选育具有较长繁殖寿命的品系（LP）与一个经31代选育以提高断奶窝重的品系（V）相比，应对生产挑战的能力。总共使用了133只繁殖母兔（分别来自LP和V品系的72只和61只）。在每个品系内，规划了三组具有不同生产强度水平的母兔：PP9组，在第一次产后第4天进行人工授精，第二次产后产仔9只；第一次断奶（30天）后进行人工授精，第二次产后产仔9只（PW9）或产仔5只（PW5）。对繁殖性能、体况（肾周脂肪厚度（PFT））和脂解反应进行了监测。LP品系的母兔在第二次产后的平均活重（LW；重128克；P<0.05）、PFT（厚0.47毫米；P<0.05）和估计体能量（EBE；高0.29兆焦/千克；P<0.01）均高于V品系的母兔。然而，第一次产后配种的LP品系母兔在第二次产后的EBE与V品系母兔相比无显著差异。在泌乳的第一周，两个品系的干物质（DM）摄入量相似（V和LP品系母兔分别为94和95克DM/千克LW0.75·天）。当窝仔数为9只时，两个品系在第一周的产奶量存在显著差异（LP和V品系母兔分别为60和54克奶/千克LW0.75·天；P<0.01），但当窝仔数为5只时无差异。因此，当窝仔数为9只时，LP品系母兔在泌乳的前10天PFT的恢复量比V品系母兔低（少0.6毫米；P<0.05）。然而，当窝仔数为5只时，LP品系母兔在泌乳10天时的LW高于V品系母兔（高210克；P<0.05），且PFT的恢复量相似。在泌乳的最后3周，当窝仔数为9只时，LP品系母兔的采食量（高6克DM/千克LW0.75·天；P<0.05）和产奶量（高27克/天；P<0.001）均高于V品系母兔，导致泌乳30天时LW无显著差异。然而，当窝仔数为5只时，两个品系的采食量和产奶量相似，泌乳30天时仍保持LW的差异（LP品系母兔高206克；P<0.05）。这些结果表明，与选择繁殖强度的品系相比，选择繁殖寿命的兔品系在应对生产挑战方面更强健。
