Maternal undernutrition induced by a lower natural pasture allowance affects muscle characteristics in newborn lambs

• Published in: Small ruminant research 2023-12, Vol.229, p.107124, Article 107124
• Main Authors: Ithurralde, J., Pérez-Clariget, R., Abud, M.J., Álvarez-Oxiley, A., Casal, A., Astessiano, A.L., Bielli, A.
• Format: Article
• Language: English
• Subjects: Fetal programming; mRNA; myogenesis; sheep
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/j.smallrumres.2023.107124

We evaluated the effects of differential levels of maternal nutrition induced by contrasting natural pasture allowances (days -23 to 122 of gestation) on newborn lamb’s muscle characteristics. Multiparous ewes were assigned to two nutritional treatments: High-pasture-allowance (HPA) ewes grazed on natural grasslands at 10-12kg of dry matter (DM)/100kg of BW/day; and Low-pasture-allowance (LPA) ewes grazed on 5-8kg of DM/100kg of BW/day. Samples (Semitendinosus and Longissimus lumborum) were collected from eighteen (9/treatment) male newborn lambs. LPA treatment reduced fiber diameter, nuclei number/fiber and muscle tissue proportion (P≤ 0.0002) and tended to reduce fiber density (P = 0.097) in the studied muscles. A lower maternal pasture allowance reduced DNA concentration and increased protein/DNA ratio in both muscles (P ≤ 0.002). LPA treatment reduced (P = 0.046) protein concentration in the Semitendinosus. Muscles from LPA lambs showed greater mRNA expressions of MyHC-I and PAX7 (P ≤ 0.014), lower mRNA expression of IGF1 (P = 0.008) and tended to show increased mRNA expression of GLUT-4 (P = 0.09). The Longissimus from LPA showed higher mRNA expressions of GLUT-4 (P=0.032). Our results demonstrate that a reduced gestational pasture allowance induces several negative effects that might seriously limit postnatal muscle growth. Although LPA muscles showed some insights which could indicate an attempt to compensate for the negative effects (greater GLUT-4 and PAX7 expressions), the local endocrine (autocrine-paracrine) environment (reduced IGF1 expression) could be a major limiting factor for such compensation. Thus, a lower maternal pasture allowance affects newborn lambs muscle characteristics with possible future effects over animal health and meat-producing performance. •Maternal undernutrition reduced the mean fiber diameter in newborn muscles.•Maternal undernutrition reduced the number of nuclei/fiber in newborn muscles.•Maternal undernutrition reduced muscle DNA content and increased protein/DNA ratio.•Maternal undernutrition affected MyHC-I, PAX 7 and IGF-1 mRNA expression.•Postnatal growth might be affected by maternal undernutrition.