Ovulation, ovarian function, and reproductive performance after treatments with GnRH in postpartum suckled cows.

Two experiments were conducted to determine whether treatments with gonadotropin releasing hormone (GnRH) during the early postpartum period in suckled cows would induce ovulation and initiate regular estrous cycles. In Experiment I, 0, 100 or 200 microg of GnRH was given to 22 suckled Angus x Holstein cows at three and again at five weeks postpartum. Serum luteinizing hormone (LH) responses did not differ between cows given 100 or 200 microg of GnRH. Treatment with GnRH tended to increase the percentage of cows exhibiting estrus by 30 and 60 days postpartum, but reproductive performance during the breeding season did not differ among groups. In Experiment II, 70 suckled Hereford cows were given either no treatment or 200 microg of GnRH at 7 weeks postpartum. Cows given GnRH received either no treatment prior to GnRH or were separated from their calves for 24 hr prior to GnRH treatment. Half of the cows that were separated from their calves also received progesterone via a progesterone intravaginal device (PRID) for 12 days prior to calf removal. Treatment with GnRH alone tended to increase the percentage of anestrous cows which ovulated by 8 days after treatment. Calf removal did not increase the ovulatory response to GnRH, but PRID treatment did. More estrous periods were detected in GnRH-treated cows than in control cows during 20 days after GnRH treatment.

Molecular phylogeny based on the kappa-casein and cytochrome b sequences in the mammalian suborder Ruminantia.

Nucleotide sequences for the kappa-casein precursor proteins have been determined from the genomic DNAs or hair roots of the Ruminantia. The coding regions, exons 2, 3, and 4, were amplified separately via the three kinds of PCRs and then directly sequenced. The primers were designed from the sequence of bovine kappa-casein gene; they were applicable for the amplification of the kappa-casein genes from the 13 species in the Ruminantia except exon 2 of the lesser mouse deer. These results permitted an easy phylogenetic analysis based on the sequences of an autosomal gene. A phylogenetic tree was constructed from the mature kappa-casein sequences and compared with the tree of the cytochrome b genes which were sequenced from the same individuals. The Cervidae (sika deer, Cervus nippon) were separated from the branch of the Bovidae on the tree of kappa-casein genes with a relatively high confidence level of the bootstrap analysis, but included in the branch of the Bovidae on the tree of cytochrome b genes. The kappa-casein tree indicated a monophyly of the subfamily Caprinae, although the internal branches were uncertain in the Caprinae. The tree based on the nucleotide sequences of cytochrome b genes clearly showed the relationships of the closely related species in the genus Capricornis consisting of serow (C. smatorensis), Japanese serow (C. crispus), and Formosan serow (C. swinhoei). These results would be explained by the difference of resolving power between the kappa-casein and the cytochrome b sequences.