The strategic use of natural shade and iodine supplementation at the time of joining led to an improved fertility of tropical Merino ewes. This was most pronounced when ambient heat stress was greatest (p <O.Ol). A higher incidence of oestrus and a higher pregnancy rate in mated animals both contributed to the improved fertility. Heat' stress conditions experienced during summer in a tropical s...

Blood serum progesterone (P4) levels in donor cows and heifers at donor selection, superovulation, insemination and embryo recovery were investigated. Significant differences in P4 levels in the investigated donors during superovulatory oestrus insemination were observed. The cows with low levels of P4 at insemination (5.8 ± 1.7 nmol/l) showed a better yield and quality of embryos (P<0.01) comp...

The aim of the present study was to examine the distribution of oestrogen receptor alpha (ERα) in the uterus of sows with reproductive disturbances as well as to study the expression of ERα in relation to plasma oestradiol-17β (E2) and progesterone (P4) concentrations in the blood. Crossbred 3–4 parity Lithuanian White x Danish Landrace breed sows presenting various reproductive disturbances we...

The expression of oestrus in ewes may be influenced by previous nutritional *history. Smith (1966) reported that restricted nutrition during the spring delayed or reduced the expression of oestrus in Merino ewes during the following autumn, even though nutrition had been improved and ewe live weights had recovered before the rams were introduced. Hunter (1962) and Smith (1962) have also suggest...

A study was done to evaluate the effect of using progesterone (P4) intravaginal device (CIDR: controlled internal drug-releasing dispenser) to synchronise the return to oestrus of previously timed inseminated (TAI) dairy heifers, and to evaluate embryo survival and pregnancy rate (PR) in the return to oestrus heifers. At the onset of the artificial insemination (AI) breeding period (day -9), he...

The kisspeptin/Gpr54 signaling pathway plays a critical role in reproduction by stimulating the secretion of GnRH, yet mice carrying mutations in Kiss1 (which encodes kisspeptin) or Gpr54 exhibit partial sexual maturation. For instance, a proportion of female Kiss1−/− and Gpr54−/− mice exhibit vaginal oestrus, and some male Kiss1−/− and Gpr54−/− mice exhibit spermatogenesis. To characterise thi...

A total of 16 crossbred repeat breeder cows were treated with norgestomet (Syncromate-B) ear implants for nine days. At the time of implant insertion, two ml of SMB injection was adminisetred to all the cows intramuscularly on day 10 of the oestrous cycle to induce oestrus. AI was done at 48 and 72 h after implant removal. Pregnancy diagnosis was done at 60 days following AI after induced oestr...