The objective of this trial was to evaluate the body weight change as well as the diameters and numbers of muscular fibers of the Semitendinosus muscle of lambs from birth until weaning that were born from Santa Inês ewes supplemented at different stages of gestation. Seventy-three Santa Inês ewes averaging 45.11 kg of body weight (BW) that were bred with three Dorset rams were randomly assigned to the following treatments during pregnancy: 1) control (CO): tanzaniagrass pasture (Panicum maximum Jacq.) plus cassava by product during the entire gestation; 2) initial third (IT) - CO plus supplementation from the 1st to 50th day of gestation; 3) medium third (MT) - CO plus supplementation from the 50th to 100th day of gestation; 4) final third (FT) - CO plus supplementation from the 100th day of gestation to birth. The birth season occurred from November 23/2003 to January 03/2004. Treatments did not affect the lambs BW at birth (BWB), at 30 days of age (BW30), and at weaning (BW60), which averaged 4.02, 9.19, 16.40 kg, respectively. The average daily weight gain from birth to weaning (ADG 0-60) also did not differ across treatments showing a mean value of 0.21 kg/day. The type of birth (single or twins) significantly affected the BWB, BW30, BW60, and ADG 0-60. No significant differences were observed in the diameters of muscular fibers at birth (11.61 mm) and at weaning (27.65 mm) comparing all treatments. The number of muscular fibers, weight, and length of the semitendinosus muscle averaged 1,454, 21.04 g, and 8.43 cm, respectively, and were all unaffected by the supplementation at different stages of pregnancy. It can be concluded that supplementing ewes during gestation is not recommended if animals are fed tanzaniagrass plus a cassava by-product (CO treatment).
growth; sheep; supplementation
