title: Effects of seasonal changes on the ovulation rate and embryo quality in superovulated Black Suffolk ewes.
abstract: OBJECTIVE
  The objective of this study was to investigate the effects of seasonal changes on the superovulation in Black Suffolk ewes, particularly the ovulation rate and embryo quality.
  
  
  METHODS
  Black Suffolk ewes were superovulated either in May (n=22) or in September (n=21), 2013. After estrus synchronization with CIDR, the donor ewes were superovulated with PMSG and seven decreasing doses of FSH (twice daily at 07:00 and 19:00 for four consecutive days. Then, they were subjected to laparoscopic intrauterine artificial insemination. The viable morula and blastocysts were recovered and immediately transferred to recipients.
  
  
  RESULTS
  Ewes that were superovulated in May had a much higher ovulation rate than those were superovulated in September (16.8 ± 3.23vs. 10.2 ± 2.94, p<0.01); however, the viability rate of the embryo was lower than that of September (56.0 ± 1.92% vs. 92.5 ± 3.26%, p<0.01). There was no significant difference in the survival rate of the transferred viable embryos (33.9 ± 1.00% vs. 36.7 ± 1.64%, p>0.05) and the number of offspring per donor ewe (3.1 ± 0.54 vs. 2.9 ± 0.72, p>0.05) between May and September. In contrast, the offspring/ova ratio of the donor ewes superovulated in May was lower than that of September (18.5 ± 1.64% vs. 32.8 ± 2.14%, p<0.01).
  
  
  CONCLUSIONS
  The superovulation of Black Suffolk ewes may be affected by the seasonal changes. Generallly, The ewe's ovulation rate was higher in May, whereas the viability rate of embryo was higher in September.
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Shi
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Jin-Yun
authors.initials: JY
authors.lastname: Yi
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Xiu-Zhi
authors.initials: XZ
authors.lastname: Tian
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Zheng-Xing
authors.initials: ZX
authors.lastname: Lian
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Han
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Jun-Cai
authors.initials: JC
authors.lastname: Fu
authors.affiliation: College of Animal Science, Jilin University, Changchun, China.
authors.forename: Wen-Fa
authors.initials: WF
authors.lastname: Lv
authors.affiliation: Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, National Key Laboratory of animal nutrition, China.
authors.forename: Guo-Shi
authors.initials: GS
authors.lastname: Liu
mesh_terms: D000818:Animals; D004624:Embryo Transfer / Q000662:veterinary*; D047108:Embryonic Development / Q000502:physiology*; D004973:Estrus Synchronization / Q000379:methods; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary*; D010535:Laparoscopy; D011247:Pregnancy; D012621:Seasons; D034561:Sheep, Domestic / Q000502:physiology*; D013480:Superovulation / Q000502:physiology*