Puberty in breeds of female hair sheep in Northeast Brazil

Abstract

This experiment was carried out with 112 ewe lambs, 32 of Morada Nova breed (MN), 63 Brazilian Somali (BS), and 17 Santa Inês (SI); grazing in native pasture at the Brazilian National Goat Research Center, CNPC, Sobral, CE, Northeast Brazil (3° 42' south latitude and 40° 21' west longitude). Lambs were weaned in groups averaging 112 days of age. Live body weights were recorded at birth and at four-week intervals until the first puberal estrus. Estrus was detected by using Leaser rams. The date, time of day and live body weights were recorded to obtain the age and weight at first puberal estrus. Between 40 to 60 hours after estrus was detected, the ovaries of each ewe lamb were observed by laparotomy to determine the occurrence and rate of prepuberal (CA) and puberal (CL) ovulations. The overall mean age and weight at puberty were 306.3 ± 5.6 days and 20.7 ± 0.3 kg, respectively. The SI breed (24.0 ± 1.0 kg) was statistically (P < 0.05) heavier at puberty than the MN (21.2±0.6 kg) and BS (19.7±0.4 kg) breeds. No statistical differences were found (P > 0.05) among breeds for age at puberty. There was no statistical difference (P> 0.05) for weight or age at puberty due to type of birth. A significant (P < 0.05) influence of year on weight and age at puberty was found. No differences (P > 0.05) were found among breeds for incidence and rate of ovulation. All ewe lambs ovulated at puberal estrus with a mean ovulation rate of 1.31. During prepuberal period, 78.35% of the ewe lambs ovulated with an ovulation rate of 1.13.