ABSTRACT
The effect of dietary yeast culture (YC) supplementation during pre-mating and gestation periods on some physiological responses was studied in 48 Suffolk crossbred ewes aged 3-4 years and weighed 58.54 ± 1.34 kg. The animals were divided into 3 comparable groups. The 1st group was fed a basal ration composed of 60% concentrate feed mixture (CFM) plus 40 % clover and rice straw. The 2nd and 3rd groups fed the same basal ration which supplemented daily with 2.5 or 5.0 g YC added to a part of the ground CFM, respectively. Results showed that YC supplementation improved significantly (P<0.05) reproductive ability, prolificacy, lambs born/ewes joined, lambs weaned/ewes lambed, kg of lambs born or weaned/ewes joined or /ewes lambed and insignificantly affected conception rate, fertility, fecundity and twinning frequency compared to those of control ewes. It also resulted in higher (P<0.05) serum albumin, glucose, urea concentration and AST activity but it decreased cholesterol concentration (P<0.05) than control ewes. Serum albumin and urea did not significantly differ among gestation periods. However, total protein, globulin, glucose and cholesterol concentrations progressively increased (P<0.05) with the advancement of pregnancy especially up to the 15th week of gestation followed by a decrease up to lambing. The A/G ratio showed an opposite trend (P<0.05), meanwhile creatinine concentration and activity of AST and ALT were fluctuated. Rectal and skin temperatures, pulse rate and respiration rate were lower (P<0.05) in YC supplemented ewes than those in control ones. It can be concluded that yeast culture supplementation could be safely added to ewes ration at 5.0 g /d/head during pre-mating and gestation periods in order to improve the reproductive performance, blood components and thermo-cardio-respiratory responses without any adverse effects on liver and kidney functions.