Sexual performance of Awassi ram lambs reared in different sex composition groups

Abstract

The objective of this study was to evaluate the effect of sex composition of the group of lambs before puberty on later sexual performance in Awassi ram lambs. Thirteen Awassi ram lambs of the same age were raised in either all-male group ( n = 7) or in a group mixed with females ( n = 6) from weaning to puberty. Blood samples, body weights (BW) and scrotal circumferences (SC) of ram lambs were recorded between eight and 10 months of age. Sexual performance testing was performed at 9 months of age by individually exposing ram lambs to oestrous females on five occasions. Body weight and SC were greater ( P < 0.01) in the all-male compared with the mixed group. Plasma testosterone concentrations were not influenced ( P > 0.05) by treatment. Plasma testosterone concentrations were significantly correlated ( P ≤ 0.05) with BW ( r = 0.3) and SC ( r = 0.4). No treatment effects were detected regarding bouts of leg-kicking. Bouts of anogenital sniffing, the frequency of mount attempts and mounting frequency were greater ( P < 0.05) in the all-male group. Even though the frequency of raising the fat tail of females was similar between the two treatments, the mixed group tended to be ( P = 0.08) more efficient in doing so than the all-male group (higher tail raising/mount). Results of the current study indicate that mixing groups of ram and ewe lambs before puberty may be insufficient to improve later sexual performance of ram lambs.