Effects of feed intake restriction during late pregnancy on maternal metabolic changes and fetal development in ewes

Abstract

This study investigated the effects of feed intake restriction during late pregnancy on maternal metabolic changes and fetal development in ewes. Six ewes out of 35 Mongolian ewes were slaughtered at the beginning of the experiment and the remaining 29 animals were allocated to three different groups: Restricted Group 1 (RG1; 0.175 MJME BW-0.75/day, n = 12), Restricted Group 2 (RG2; 0.33 MJME BW-0.75/day, n = 9), and Control Group (CG; ad libitum, 0.67 MJME BW-0.75/day, n = 8). At 140 days (d) of gestation, 6 representative ewes from each group were slaughtered. The results indicated the maternal net body weight loss, the concentrations of glucose (GLU) (120 d), GLU (140 d), total amino acid (TAA) (140 d), total protein (TP) (140 d), albumin (ALB) (140 d), and globulin (GLB) (140 d) were significantly (P < 0.01) decreased, while those of nonesterified fatty acid (NEFA) (120 d), NEFA (140 d), β-hydroxybutyric acid (BHBA) (120 d), and BHBA (140 d) in maternal plasma were greatly enhanced in RG1 group compared to CG group (P < 0.01). For RG2 group, a significant decrease of the maternal net body weight loss (P < 0.01) and the concentrations of GLU (140 d) (P < 0.01), TAA (140 d) (P <0.01), ALB (140 d) (P < 0.01), GLB (140 d) (P < 0.05), and a significant increase of NEFA (120 d) (P < 0.05) and NEFA (140 d) (P < 0.01) in maternal plasma were found in relation to CG group. Furthermore, the fetal weight was significantly reduced in RG1 and RG2 groups (P < 0.01), and body length (P < 0.05), thoracic girth (P < 0.05), thoracic depth (P < 0.05), abdomen circumference (P < 0.05), straighted crown-rump length (P < 0.01), and curved crown-rump length (P < 0.01) in RG1 group were also decreased compared to CG group. With the decrease of nutrient level during late pregnancy, the maternal protective buffer system in RG2 group still played a major role, but the system in RG1 group might have been destroyed, which resulted in serious impacts on the fetal growth and development.