Résumé:
The aim of this work is to study the impact of nutrition on reproduction through the analysis of biochemical blood parameters and the determination of the body condition of the ewes at different physiological stages and moreover to provide a reference interval of biochemical blood parameters in Ouled Djellal ewes.
This work was conducted on 183 ewes Ouled Djellal reared in a public farm in Ibn Ziad located in the northwest of Constantine (eastern Algeria) during two breeding seasons (2011- 2012) and (2012 -2013). Samples were performed on healthy ewes, aged between 2 and 5 years, primiparous and multiparous, with an average live weight of 51.3 ± 7,7kg at different physiological stages (mating period, early pregnancy, mid pregnancy, late pregnancy, early lactation, mid lactation and weaning period). Meanwhile a body condition score (NEC) mean was assigned to each ewe. The animals have been classified into 3 groups according to their body condition: Group 1: G1 (NEC≤2,5) Group 2: G2 (2.5> NEC <3) and group 3: G3
(NEC≥3). The Weighing were also carried out on ewes during the dry and the lactation period, as well as on the newborn lambs.
Blood glucose, cholesterol triglycerides, urea, albumin, creatinine, plasma concentration of minerals (Ca, P, Na, K, Cl, Mg and Fe) and enzymatic activity (ALAT, ASAT) varied significantly depending on the physiological stage. The litter size during gestation significantly affects the plasma concentrations of triglycerides, Na, K, and Cl. The effect of the dry period parity was significant on the plasma concentrations of triglycerides, total protein, albumin, and Mg. Depending on the fertility, empty sheep had significantly lower plasma levels of urea and Mg, whereas regarding to prolifcity; the sheep that had twins had lower plasma concentrations of triglycerides and higher Mg in times of mating.
The NEC’s sheep varies significantly depending on the physiological stages and on the parity.
Fertility and prolificity increased significantly with the increase of body condition score (NEC≥3) during the preparation of mating. The litter weight was significantly higher in ewes whose NEC ≥3 in mid and late gestation. This study also showed a significant positive correlation between NEC and cholesterol, creatinine, albumin and plasma concentrations (Ca, Na, K, Cl and Mg), and a significantly negative correlation between NEC and uremia.
In conclusion, the biochemical blood parameters and the body condition are very useful to evaluate nutritional status of ewes and its impact on production and reproductive performances in sheep.
