New Zealand Journal of Agricultural Research abstracts
Sexual activity and puberty in pure Awassi and crosses and
backcrosses with Charollais and Romanov sheep breeds
Rami T. Kridli*
Abdullah Y. Abdullah
Department of Animal Production
Faculty of Agriculture
Jordan University of Science and Technology
Irbid 22110
Jordan
Mohamed Momani Shaker
Institute of Tropical and Subtropical Agriculture
Czech University of Agriculture
Prague, Czech Republic
Mahmoud K. Masa’deh
Department of Animal Science
College of Agriculture
University of Nebraska-Lincoln, USA
*Corresponding author: rkridli@just.edu.jo
Abstract The aim of this experiment was to
study sexual
activity, scrotal circumference and the occurrence of puberty in five
breed groups of ram lambs. Awassi (A, n = 8), F1
Charollais-Awassi (CA, n = 5), backcrossed
Awassi-Charollais-Awassi (ACA, n = 9), F1
Romanov-Awassi (RA, n = 9) and backcrossed
Awassi-Romanov-Awassi (ARA, n = 8) ram lambs were randomly
selected at weaning to be used in this study. Sexual activity was
observed weekly by introducing two oestrous ewes into each male group
for a period of 20 min. At the time of first expressed sexual
interest in females, body weights (BW) (P < 0.05) and scrotal
circumferences (SC) (P < 0.001) differed among ram breed
groups, while age and testosterone concentrations were similar. Weights
at puberty were similar among the ram breed groups. Puberty, however,
occurred earlier (P < 0.01) in CA, RA and ACA than in A and
ARA ram lambs. At puberty, testosterone concentrations were similar
while SC were greater (P < 0.01) in CA, ACA and RA than in
ARA ram lambs. However, greater (P < 0.05) testosterone
concentrations were observed in crossbred than in Awassi ram lambs
throughout the study. Similarly, BW and SC were greater (P <
0.05) in CA, RA and ACA than in A and ARA ram lambs throughout the
study. Results of the present study indicate that crossbreeding Awassi
with Charollais and Romanov sheep breeds improved reproductive
parameters in the F1 crosses and the backcrossed ACA males
compared with the ARA backcrosses and pure Awassi ram lambs. The fact
that age differed among ram groups while BW at puberty did not,
indicates that body weight is more important than age for puberty
occurrence.
Keywords crossbreeding; puberty; ram lambs;
scrotal
circumference; sexual activity
A07002; Online publication date 19 September 2007; Received 22
December 2006; accepted 29 June 2007
New Zealand Journal of Agricultural Research, 2007, Vol. 50:
429–436
0028–8233/07/5004–0429 © The Royal Society of New Zealand 2007
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