Effect of Pre-Pubertal Plan of Nutrition on Reproductive Performance, Hormone Concentrations and Milk Production in Kurdish Female Lambs

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 post-weaning 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 preweaning 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 post-weaning, 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 concluded that pre-pubertal plan play an important role in secretion of progesterone, insulin and leptin, which can leads to early sexual puberty. And also these strategic plans should be improve economic traits the start of lamb's puberty in sheep husbandry.