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چکیده
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To determine the value of pre-pubertal plan of nutrition on reproductive performance, hormonal concentrations and milk production in ewe lambs, a total of 40 clinically health Kurdish female lambs (30±8.6 d and weighing 10.2±3.4 kg) were randomly allocated to one of two experimental diets in pre-weaning period: high quality diet (HQD) (HQD, 2.50 Mcal ME/kg dry matter (DM) and 148 g CP/kg DM) or low quality diet (LQD) (LQD, 2.02 Mcal ME/kg DM and 87 g CP/kg DM). At weaning, one half of lambs from each group was randomly separated and assigned to HQD or LQD. There were four treatment groups in postweaning period: H-H (HQD pre-and post-weaning); H-L (HQD pre-weaning and LQD post-weaning); L-H (LQD pre-weaning and HQD post-weaning) and L-L (LQD pre and post-weaning, control group). Dry matter intake was measured weekly and body weight (BW) and average daily gain (ADG) were measured every 2 weeks from 30 to 210 d of age. Serum insulin, leptin and progesterone concentrations were determined by ELISA. In general, the HQD treatment increased dry matter intake (DMI), compared with the LQD treatment during pre-weaning period (P<0.01). Results showed that initial BW was similar between all experimental groups (P>0.05). During post-weaning, lambs of H-H treatment had higher DMI, metabolize energy (ME) and crude protein (CP) intake compared with other lambs treatments (P>0.05). Within the postweaning, serum progesterone concentrations was greater for ewe lambs fed at H-H group than for other groups (P<0.05). Serum insulin concentration was affected by the diet quality at both periods (P<0.05). Leptin concentration was affected by treatment and ewe lambs of L-H group had higher leptin concentrations (P<0.05). Age at the time of puberty was affected by treatments (P<0.05). In addition, Ewe lambs in the H-H and L-H groups were younger and weighed more at puberty. Diet plan in the pre-pubertal period was affected milk yield at the first lactation (P<0.05). It was
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