Effect of controlled breeding on the fertility of Awassi and Red Karaman ewes and the performance of the offspring

• Published in: Small ruminant research 2006-11, Vol.66 (1), p.230-235
• Main Authors: Emsen, E., Yaprak, M.
• Format: Article
• Language: English
• Subjects: animal breeding; animal performance; Awassi; birth weight; controlled internal drug release devices; estrus synchronization; ewes; fecundity; female fertility; fluorogestone acetate; Flushing; hormone supplements; Lambing rate; mortality; multiple births; nutritional flushing; progeny; progesterone; Red Karaman (sheep breed); reproductive efficiency; Sheep; sheep breeds; Synchronization; twins; weaning weight
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/j.smallrumres.2005.09.022

This study was aimed at determining the effects of progestagen and ovarian stimulation agents (eCG) treatment, together with nutritional flushing, on the lambing rate of Awassi (A) and Red Karaman (RK) ewes and the performance of their offspring. In the trial, 60 Awassi and 40 Red Karaman ewes and their lambs were used. Each breed was randomly allocated to two groups per breed; one being the treatment group and the other the control. Estrus was synchronized by means of fluorogestone acetate (FGA) (40 mg) intravaginal sponges (14 days) and eCG (500 IU) injected i.m. at sponge withdrawal in all treatment groups. The interval from introduction of the ram to the onset of estrus was significantly earlier ( P < 0.01) in the control, compared to the treatment group. Lambing rate was recorded as 83.3 and 93.3% in the Awassi ewes and 90.0 and 85.0% in the Red Karaman ewes for the treatment and control groups following mating, respectively. An overall higher ( P < 0.05) percentage multiple birth rate was recorded in the ewes synchronized with FGA + eCG (34.9%), compared to ewes in the control groups (13.3%). Prolificacy significantly increased following treatment with eCG from 114 to 152% in the Awassi and from 111 to 133% in the Red Karaman ewes. Most of the lambing (75%) took place over a short period of time (5 days) in the treated groups. Progestagen sponge and eCG treatment resulted in an extra 6 kg meat being produced per ewe, compared to the control groups. Birth and weaning weights of the Awassi and Red Karaman lambs were found to be similar for the treatment and control groups. The highest lamb survival rates (lowest mortalities) at weaning in both breeds (81% versus 78% and 89% versus 74% in the Awassi and Redkaraman control and treated ewes, respectively) were obtained for ewes in the control groups. It is concluded that intravaginal sponges (FGA) can be used for estrus synchronization and mating in Awassi and Red Karaman ewes during the breeding season and that treatment with eCG following progestagen treatment has the potential of increasing the twinning rate. Nutritional flushing also resulted in a higher number of lambs born in the control ewes.