Gemechu T. Dinegdie

Maternal undernutrition during gestation can impair fetal muscle development, inducing lasting consequences for offspring growth and carcass quality. This study evaluated the effects of early- to mid-gestation nutrient restriction on postnatal skeletal muscle development in Boer goat offspring. Pregnant does (n = 12 per treatment) were assigned to either a control diet (CON; 100% of NRC recommendations) or a nutrient-restricted diet (NR; 60% of CON) from days 45 to 100 of gestation, then all does were realimented to the CON diet until parturition; male offspring (n = 6 per treatment) were maintained on a CON diet until 5 months of age. Longissimus dorsi muscle samples were collected for histological evaluation of fiber number, diameter, and collagen content, and for gene expression analysis of insulin receptor (IR), insulin receptor substrate-1 (IRS1), glucose transporter-4 (GLUT4), myogenic regulatory factors (MYF5, MYF6, MYOD, MYOG), and collagen genes (COL1A1 and COL3A1) using RT-PCR. Plasma glucose and cortisol were also measured. Muscle fiber number tended to be reduced (p = 0.06) in NR offspring, accompanied by decreased MYOG expression (p < 0.05) and trends for reduced MYF5 and MYF6 expression (p < 0.10), as well as reduced IR expression (p < 0.05). Collagen content did not differ, although COL3A1 expression was increased in NR offspring. Plasma glucose was lower (p < 0.05) at 3 months, and cortisol tended to be higher (p < 0.10) at 5 months. These results indicate that maternal undernutrition during early- to mid-gestation alters postnatal skeletal muscle development in Boer goats by reducing muscle fiber number and affecting myogenic and metabolic signaling pathways. Such changes may negatively affect the efficiency of muscle growth and meat quality.