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The Thai Journal of Veterinary Medicine

Abstract

The present study investigated the association among serum insulin-like growth factor-I (IGF-I), backfatthickness, and age at first observed estrus in replacement gilts. In total, 80 replacement gilt, Landrace (L, n = 48) andYorkshire (Y, n = 32), were included. The gilts were determined for age at first observed estrus between 167 to 212days of age. They were categorized according to age at first observed estrus into ≤ 200 days (n = 41) and > 200 days (n= 36) groups. Backfat thickness, body weight, and serum IGF–I concentration were measured before mating. Age atfirst mating, interval from boar exposure to first observed estrus, and interval from entry-to-first-mating wererecorded. It was found that the level of serum IGF–I negatively correlated with age at first observed estrus (r = -0.26, p= 0.022), as well as with interval from boar exposure to first observed estrus (r = -0.28, p = 0.015), but it positivelycorrelated with backfat thickness (r = 0.37, p < 0.001). The gilts exhibiting first observed estrus at ≤ 200 days of age hadhigher serum IGF–I level (30.2±1.2 and 25.4±1.1 nmol/l, p = 0.002) and tended to have a shorter interval from entry-tofirst-mating (106.7±2.8 and 113.2±2.7 days, p = 0.082) than those exhibiting first estrus at > 200 days of age. The giltswith backfat ≥ 17.0 mm had higher level of serum IGF–I (31.1±1.1 nmol/l) than those with a backfat of 14.5-16.5 mm(26.2±1.3nmol/l, p = 0.009) and ≤ 14.0 mm (26.0±1.4 nmol/l, p = 0.008).

First Page

41

Last Page

48

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