Efecto de la nutrición materna durante la gestación sobre la calidad de la carne y la expresión génica muscular en corderos

Sheep production in Uruguay is primarily carried out in extensive systems on native pastures, where forage availability and quality vary seasonally. This situation is particularly relevant during gestation, as nutritional restrictions can affect fetal development and induce fetal programming processes with persistent effects on the offspring's productive performance. Since myogenesis occurs in the early stages of gestation, focused supplementation during critical periods could improve productive efficiency and lamb meat quality. The aim of this study was to evaluate the effect of protein supplementation between days 55 and 80 of gestation on the expression of genes associated with muscle development (MyHC-I, IGF1, and PAX7) and meat quality in the offspring, also considering the effect of sex and its interaction with the treatment. The study was conducted at Estación Experimental Bernardo Rosengurtt (FAGRO, UdelaR) during winter-spring 2023. Thirty-seven multiparous Corriedale ewes with singleton pregnancies and their respective lambs were used, distributed into two treatment groups: protein supplementation (SUP) and control (CON). Ewes grazed on native pasture and received (SUP) or no (CON) daily individual supplementation with soybean meal (1% of body weight) between days 55 and 80 of gestation. Lambs were raised until slaughter at 90 days of age. Samples were obtained from the Longissimus lumborum (LL), Gluteobiceps (GB), and Supraspinatus (SS) muscles for gene expression analysis using RT-qPCR and meat quality determinations. Statistical analysis was performed using mixed models considering the effects of treatment, sex, and their interaction. Maternal protein supplementation affected the expression of genes linked to muscle development in LL and GB, with no effect in the SS. The SUP treatment reduced the expression of MyHC-I (p = 0.01), PAX7 (p = 0.01), and IGF1 (p = 0.03) in GB, and tended to reduce the expression of MyHC-I (p = 0.07) and PAX7 (p = 0.09) in LL. Furthermore, in LL, MyHC-I expression tended to be influenced by the treatment × sex interaction (p = 0.08), with a reduction observed only in SUP males (p = 0.07). In LL, a trend toward lower pH at 24 h postmortem was observed in the SUP group. In GB, treatment effects were detected for color traits, with treatment × sex interactions in a*, b*, and C*, and a trend toward greater cooking losses in the SUP group. In SS, supplementation increased meat lightness (L*) and tended to interact with sex for shear force. Overall, the results indicate that protein supplementation during gestation can modulate muscle gene expression and affect meat quality in a muscle- and sex-dependent manner in the offspring, thus demonstrating the potential of maternal nutrition to influence skeletal muscle programming in pasture-based sheep systems.