This study aimed to evaluate the effects of supplementing ewes' diet with calcium salts of soybean oil (CSSO) during the second half of gestation on their nutritional, metabolic, and physiological parameters. Additionally, it also aimed to assess the their offspring's sex effect and its interaction with rumen-protected fat. To achieve this, 30 multiparous hair ewes pregnant from a single fetus and weighing 44.1 ± 6.9 kg were randomly divided into two feeding regimens at 75 days of gestation: (1) Control (CON; n = 16), which received a basal diet that met the basic nutritional requirements of ewes gestating a single fetus, and (2) CSSO (n = 14), which received the basal diet plus calcium salts of soybean oil at a level of 1.5 g per kg of body weight (5 % inclusion based on dry matter). The ewes and their offspring were kept together after birth, and lambs were weaned once they reached 20 kg of body weight. Results showed that CSSO ewes were heavier during late gestation and had higher body weight at lactation than CON ewes (P ≤ 0.05). However, CSSO ewes showed an earlier decline in dry matter intake during late gestation (P ≤ 0.05). CSSO ewes also had greater apparent total tract digestibility of ether extract (P < 0.01) and tended to have lower fat milk concentration by approximately 17 % (P = 0.08). In terms of gene expression, CSSO ewes had greater CPT2 expression and ACACA mRNA levels in the subcutaneous adipose tissue (P = 0.08 and P = 0.04, respectively). ACACA mRNA expressions in the maternal liver tissue were also greater (P ≤ 0.01) for CSSO ewes gestating female offspring. However, liver mRNA expressions of IGF1, PC, PCK1, GK, and PPARy were similar between feeding regimens (P > 0.05). Lambs from CSSO ewes were born 0.57 kg heavier than those from CON ewes (P = 0.01) and tended to be weaned at an younger age (P = 0.06). Additionally, CSSO lambs had greater MyoG expression than CON lambs (P = 0.05). In summary, the supplementation of ewes' diet with CSSO during the second half of gestation shows promise as a technology to enhance fetal development, as well as improve long-term maternal and offspring performance.