Live weight changes and their relationship with the ovarian status of maiden fattailed barbarine ewes

الملخص EN

The current study assessed the effect of the pattern of live weight change on the ovarian function of maiden Barbarine ewes at 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 the curve, animals were grouped into three classes LWCI (n = 46), LWCII (n = 91) and LWCIII (n = 34) with live weight loss being highest in LWCI 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).

Following synchronisation with progestagen of the females found cycling, levels of plasma IGF-I concentrations between 6 and 42 hrs after removal of sponges were not significantly different between the three classes of live weight, and respectively averaged 94.2, 90.8 and 89.8 μg / l for LWCI, LWCII and LWCIII females.

Levels of estradiol were also not significantly different between the three groups (0.73, 0.70 and 0.67 pg / 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 summer live weight-loss is elevated.