Focused high-protein supplementation to ewes grazing Campos grassland during mid gestation improves maternal-fetal blood flow and skeletal muscle mass of the progeny

Abstract

In order to evaluate the effect of focused-high-protein supplementation during the second third of gestation on placentome and uterine artery blood flow, growth and carcass composition of the progeny, 37 single-bearing ewes were used. Campos grazing ewes were divided in two nutritional treatments between 55 and 80 days of gestation: supplemented ewes (SUP; n = 22, 12 carrying female and ten carrying male fetuses) were individually daily supplemented with soybean meal at 1 % of their body weight (BW), and control ewes (CON; n = 15, nine carrying female and six carrying male fetuses) grazed adjoining Campos sub paddock without supplementation. After 80 days of pregnancy all ewes were managed together as the same flock and continued grazing on the same paddock of Campos grassland until 100 days of pregnancy when they were sheared and transferred to a multi-year pasture until lambing. Doppler ultrasonography examinations of placentome and uterine artery blood flow were performed on day 120 of pregnancy. Maternal supplementation reduced the resistance index value (P = 0.042) and tended to reduce the diastole/systole ratio (P = 0.078) in placentomes. Similarly, in the uterine artery, maternal supplementation reduced both the resistance index value (P = 0.022) and the diastole/systole ratio (P = 0.030). On the other hand, maternal supplementation did not affect lamb´s BW, body morphometric measurements or lamb´s weight gain from birth to 90 days of age (P > 0.05). Similarly, organs’ weight and carcass objective conformation traits were not affected by maternal supplementation at slaughter (90-day-old lambs, P > 0.05). Nevertheless, muscle weight expressed as a percentage of lamb BW was higher in SUP than in CON lambs (P = 0.007). Also, absolute muscle weight tended to be affected by the interaction between maternal supplementation and the sex of the lambs (P = 0.072), as male lambs born to SUP ewes had heavier muscles than CON male lambs (P = 0.059). In summary, focused high-protein supplementation offered to ewes grazing Campos grassland during the second third of gestation positively affected placentome and uterine artery blood flow but had no effect on lamb growth traits. However, our results indicate that maternal supplementation improved the BW proportion of muscles. Also, our results suggest that maternal supplementation could have influenced skeletal muscle development in a sex-specific manner, although under the conditions of the present experiment this effect was subtle and depended on the BW of the lamb.