Sexual development in Tazegzawt male lambs: body, testicular and penile growth before pre-puberty

Abstract

In sheep, measurement of body growth and testicular parameters and observations of state penile development can be useful tools to select the best breeders. The aim of this work was to study the testicular growth development in Tazegzawt lambs and the relationship with age and body growth parameters. Ten Tazegzawt ram lambs, born in the spring, comprising four from single births and six from multiple births, raised and managed under natural temperature and light were used to study the testicular development (scrotal circumference, testis diameter, testis length, tail of the epididymal diameter and estimation of testis volume) and the association with the development of body growth.

The results showed that the mean live weight in male Tazegzawt lambs was 5.0 kg at birth and 39.7 kg at 25 weeks of age. The highest average daily gain (293 g/d) was observed during the first months after birth.The increase of testicular size and penile state development were more closely associated with body weight than with age. The period from 9 - 25 weeks of age was characterised by rapid sexual development on the basis of testes and penile development. Tazegzawt lambs attained the pre-pubertal stage when the body weight exceeded 28 kg.

Significant correlations (P <= 0.001) were found between testicular (scrotal circumference, diameter, length and volume of testis and epididymal tail diameter) and body (live weight and thoracic perimeter) measurements. Thoracic perimeter, scrotal circumference, testicular diameter and testicular length were more related to lambs weight than to chronological age.