The effect of breed type and lactation status on reproductive performance in

This study was conducted to evaluate the effect of breed types and lactation status on reproductive performance of hormonally-treated Awassi ewes. A total of 282 ewes were treated with intravaginal progestagen sponges and equine chorionic gonadotropin. Ewes were mated with fertile rams following sponge removal. Lambing rate was similar between brown- and black-faced ewes, while the percentage of multiple births, fecundity and prolificacy were greater in black-faced ewes. Lambing rate and the percentage of multiple births were similar between lactating and dry ewes. Fecundity tended to be greater in lactating ewes, while prolificacy was similar regardless of lactation status. Results of the present study indicate that black-faced Awassi ewes respond better to hormonal treatment than brown-faced ewes while the lactation status does not appear to influence the ewes’ response to hormonal treatment.

[1]  E. Emsen,et al.  Effect of controlled breeding on the fertility of Awassi and Red Karaman ewes and the performance of the offspring , 2006 .

[2]  Ümit Yavuzer.  The Possibilities of Twice-Yearly Lambing of Awassi Sheep Ewes Without Using Hormones in an Organic Animal Production System , 2005 .

[3]  L. Schwalbach,et al.  Effect of progestagen and PMSG on oestrous synchronization and fertility in Dorper ewes during the transition period , 2005 .

[4]  A. Evans,et al.  Effect of ram exposure at the end of progestagen treatment on estrus synchronisation and fertility during the breeding season in ewes. , 2004, Animal reproduction science.

[5]  R. Kridli,et al.  Body Weight Change, Milk Production and Reproductive Parameters in Suckled vs. Non-suckled Awassi Ewes , 2004 .

[6]  A. Abdullah,et al.  Protocols for Estrus Synchronization in Awassi Ewes under Arid Environmental Conditions , 2002 .

[7]  R. Kridli,et al.  Reproductive Responses of Awassi Ewes Treated with either Naturally Occurring Progesterone or Synthetic Progestagen , 2002 .

[8]  S. Wildeus.  Current concepts in synchronization of estrus: Sheep and goats , 2000 .

[9]  M. Zarkawi,et al.  Induction of synchronized oestrous and early pregnancy diagnosis in Syrian Awassi ewes, outside the breeding season , 1999 .

[10]  A. Lymberopoulos,et al.  The effect of melatonin on lambing and litter size in milking ewes after advancing the breeding season with progestagen and PMSG followed by artificial insemination , 1998 .

[11]  J. Robinson,et al.  Resumption of oestrous and ovarian cyclicity during the post-partum period in autumn-lambing ewes is not influenced by age or dietary protein content , 1998 .

[12]  I. Zaiem,et al.  Vaginal sponges and different PMSG doses to improve breeding performances of Black Thibar ewes [fertility, prolificity] , 1996 .

[13]  R. Scaramuzzi,et al.  The ovarian secretion of androstenedione and oestradiol during late pregnancy and the early postpartum period in sheep with an autotransplanted ovary. , 1996, Reproduction, nutrition, development.

[14]  J. E. Wheaton,et al.  Evaluation of progesterone controlled internal drug release dispensers for synchronization of estrus in sheep , 1989 .

[15]  E. Inskeep,et al.  Effects of lactation status, progestogen and ram exposure on response to cloprostenol in ewes during the anestrous season. , 1988, Theriogenology.

[16]  I. Michailidis,et al.  Induced Breeding in Anestrous Milking Ewes of Dairy Breeds: Comparison of Norgestomet, Medroxyprogesterone and Fluorogestone in Two Regimes of PMSG , 1982 .