Influence of maternal characteristics on growth performance of Ouled Djellal lambs under semi-arid conditions in northeastern Algeria

This study evaluated the influence of maternal factors (parturition number, ewe age, live weight, and body condition score) on the growth performance of Ouled Djellal lambs raised under semi- intensive production systems in northeastern Algeria. Data were collected from 2,605 lambs born between 2015 and 2021 and their 1,607 dams aged between one and ten years. The animals originated from three regions in northeastern Algeria: Constantine, Bordj Bou Arréridj, and Oum El Bouaghi. Body weights of lambs were recorded at birth and at 30, 60, 90, and 120 days of age (W30, W60, W90, W120), and average daily gains (ADG0–90, ADG90–120, ADG0–120) were calculated. General linear models were applied to examine the effects of maternal factors on lamb growth traits. Birth weight was not significantly affected by maternal factors, whereas significant differences in growth emerged during the pre-weaning period. Ewe live weight and body condition score showed consistent and strong effects (P<0.001), while ewe age and parturition number had more variable effects depending on their interaction with nutritional status. Lambs from heavier (> 60 kg) and better-conditioned ewes (body condition score ≥ 2.5) were generally heavier and grew faster in the pre-weaning period compared to those from lighter or thinner ewes. Interaction analyses revealed that maternal factors influenced growth performance not only independently but also in combination. The strongest effects were observed for the interaction between ewe live weight and body condition score, whereas the combined effects of age and parturition number were less pronounced. Most differences were significant during the pre-weaning period, while post-weaning growth showed reduced variation among groups. Overall, maternal nutritional status, reflected by ewe live weight and body condition score, was the principal factor affecting lamb growth, while ewe age and parturition number acted as secondary factors. These findings highlight the importance of maintaining adequate ewe condition before lambing and considering the combined effects of maternal traits to improve lamb performance and flock productivity under semi-arid conditions.