During the breeding season three experiments were conducted to evaluate the LH and testosterone (T) response of rams with male sexual orientation (e.g., male-oriented homosexual rams) to female sheep, to male sheep, and to treatment with LHRH. Male-oriented rams were identified through a series of sexual performance and sexual preference tests. Treatments included exposure to estrous females an...

To investigate uterine and serum Ca(++) and Mg(++) variations during the estrous cycle in the bovine, 66 genital tracts and blood samples were collected from Urmia abattoir, Urmia, Iran. The phase of the estrous cycle was determined by examination of the structures present on ovaries and uterine tonicity. Of the collected samples, 17 were pro-estrus, 12 estrus, 14 metestrus and 23 diestrus. The...

We hypothesize that insemination with fresh extended semen will improve the AI pregnancy rate due to its prolonged longevity in female reproductive tract compared to frozen thawed semen. The objective of this trial was to determine the effect of fresh and frozen semen on fixed-time AI pregnancy rate in beef cows synchronized with progesterone based CO-Synch protocols and inseminated at differen...

Corpus luteum (CL) function following spontaneous or prostaglandin F2 alpha-induced estrus was studied in 27 Brahman cows and 16 Brahman heifers. Females received one injection of 0, .38, .75 or 2.25 mg alfaprostol (PGF)/100 kg body weight at 12 +/- .1 d post-estrus. Serum progesterone (P4) during CL formation, following the subsequent estrus, increased over time (P less than .001, 1 to 13 d po...

Several managerial and pharmacological methods are available for porcine estrus synchronization. Before implementing a method, producers must have a clear idea of the goal of estrus synchronization and a realistic expectation of the outcome. Induction of precocious puberty in gilts is perhaps the most economically favored estrus synchronization technique available to swine producers. Appropriat...

Embryos from Bos indicus are more resistant to elevated culture temperature (i.e. heat shock) than embryos from some Bos taurus breeds. The present experiment was designed to determine if Brahman embryos have greater resistance to heat shock than Holstein embryos at a stage in development before the embryonic genome was fully activated. A second objective was to test breed effects on estrus syn...

To investigate uterine and serum copper (Cu) and zinc (Zn) concentrations variation during the bovine estrus cycle , 232 blood and genital tract samples were collected from the abattoir in Urmia. The phase of the estrous cycle was determined by the examination of the ovaries and the uterine tonicity. Of the 46 samples selected for use in the study, 13 were pro-estrus, 10 estrus, 8 metestrus, an...

The mating behaviour of 2 jacks, each with 21 non-pregnant jennies, was studied when the jennies were in natural oestrus and simultaneously induced oestrus. The main observations were: efficient pasture breeding at natural and induced oestrus, a territorial sociosexual structure, prolonged pre-copulatory interaction, gradual increase of mating activity up to 2 days before ovulation, a copulator...

Female dogs mounted other females more frequently when the 2nd bitch was in estrus, but the hormonal state of the mounting individual had little influence upon mount frequency; estrogen rendered a female more pro­ vocative or stimulating and more cooperative or receptive to mounting by another dog. During heterosexual tests estrous females tended to mount males selectively, responding readily t...

This study was aimed to determine whether the presence of sexually stimulated rams by photoperiodic and melatonin treatments can advance the resumption of post-partum sexual activity in Mediterranean ewes lambing in January and weaned at the end of the breeding season at 41°N, in March. Rams were exposed to two months of long days (16 h light/day) and given three melatonin implants at the end o...