Live Weight Changes and Their Relationshipwith the Ovarian Status of MaidenFat-­Tailed Barbarine Ewes

The current study assessed the effect of the pattern of live weight change on the ovarian function of maiden Barbarine ewesat approximately 1 year of age. For this purpose, a total of 171 weaned ewe lambs (mean live weight ± s.d. 34.7±3.07 kg and mean age± SD 196±10 days at weaning) were selected for the experiment. Adjustment of live weight variation was used. Based on the slope of thecurve, animals were grouped into three classes LWCI (n=46), LWCII (n=91) and LWCIII (n=34) with live weight loss being highest inLWCI and lowest in LWCIII. Following laparoscopy at 13 months of age, the proportion of ewe lambs found cycling in LWCIII (85.3%)was higher in comparison to animals in LWCI (43.4%;; P 0.001) and tended to be superior to those in LWCII (61.5%;; P 0.05). Followingsynchronisation with progestagen of the females found cycling, levels of plasma IGF-­I concentrations between 6 and 42 hrs after removalof sponges were not significantly different between the three classes of live weight, and respectively averaged 94.2, 90.8 and 89.8 μg/l forLWCI, LWCII and LWCIII females. Levels of estradiol were also not significantly different between the three groups (0.73, 0.70 and 0.67pg/ml for LWCI, LWCII and LWCIII ewe lambs, respectively). It was concluded that, in low input systems of semi-­arid and arid Tunisia,mating ewe lambs at the approximate age of 1 year is likely to lead to depressed reproductive performance particularly when the summerlive weight-­loss is elevated.