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Abstract Conceiving during the early postpartum period, when ewes are investing energy resources nursing an offspring is energetically demanding. Moreover, it requires artificial weaning during ewe gestation, which induces a… Click to show full abstract
Abstract Conceiving during the early postpartum period, when ewes are investing energy resources nursing an offspring is energetically demanding. Moreover, it requires artificial weaning during ewe gestation, which induces a strong stress response. All this together can impact fetal growth and lambs’ mortality rate. The aim of the study was to determine if conceiving during the lactation and rearing period affects lambs’ weight and body temperature, and ewe and lamb behaviors after birth. Ewes were induced to ovulate during October (spring) and lambed in autumn. When they conceived, they either remained lactating while nursing their current offspring (LAC, n = 10) or had their last parturition the previous year (CON, n = 49). Lambs born from LAC ewes were lighter than those born from CON ewes (4.13 ± 0.35 kg vs 4.77 ± 0.26; P = 0.02, respectively). More LAC ewes lambed lying down than CON ewes (100 % vs 42.9 %; P = 0.03). At birth, lambs born from LAC ewes made more attempts to stand up (11.4 ± 2.2 vs 6.1 ± 1.1, P = 0.043), and had a longer latency before first suckling (79.4 ± 11.2 s vs 45.6 ± 5.9 s; P = 0.012) than lambs born from CON ewes. At the end of a separation-reunion test performed 24–36 h after birth, LAC ewes were further away from their lambs than CON ewes (5.1 ± 1.0 m vs 2.95 ± 0.54 m; P = 0.045). Lambs born from LAC took longer than those born from CON ewes to meet their mother (24.9 s vs 8.5 ± 3.5 s ± 7.7; P = 0.059), and suckle (142.5 ± 22.8 s vs 86.3 ± 10.3 s; P = 0.029). Overall, conceiving during the lactation and rearing period affected the establishment of the ewe-lamb bond. More LAC ewes lambed lying down, their lambs were lighter and less vigorous after birth. LAC ewes were less interested in their lamb, both at parturition and during the separation-reunion test. LAC ewes were less disposed to invest in their lamb, both at parturition as well as during a separation-reunion test performed the day after birth. On the other hand, although lambs from LAC ewes were less vigorous, they tended to require more attention during the short separation test. These results highlight the need of research to develop strategies aiming to improve the welfare of ewes and lambs in accelerated lambing systems.