Abstract
The symptoms of estrus in time lapse which was induced by estrogens and pregnant mare serum gonadotropin (PMSG) in 40 prepuberal gilts were comparatively examined with those of the first estrus spontaneously induced in puberal gilts.
Forty prepuberal gilts at age of 160 up to 193 days received injections of varying doses of 0.2, 0.4 or 0.8mg of estradiol benzoate, or injections of other estrogens or PMSG, such as 0.2mg of estradiol benzoate plus, 5mg of estradiol dipropionate, 10mg of estriol, 2.5mg of diethylstil boestrol or 500IU of PMSG.
There were no significant differences in the layers of epithelial cells collected by biopsy of veginal vestibular mucosa accoring to varying doses of estradiol derivatives or varying estrogens or PMSG.
However, statistically significant differences could be noted at 3 of each test group in the changes of mucosal epithelial cell laper between the first estrus spontabeously induced and of estrus induced by estrogens and PMSG. The mucosal epithelial cell layer of the vaginal vestibule was the thickest amounting to 109.6μ at day 3 after the start of prepu beral stage of the gilts with the first estrus spontaneously induced, while the thickness in the PMSG group and that of the estrogen group at day 4 after the injection were 98.8μ and 85.5μ, respectively, which were the thickest of these groups.
Redness and swelling of valva were the most notable at day 3 in each group after initiating the experiment, and significant differences could found out among these groups in terms of the changes in time lapse. The variations in the widths of valva revealed that the width at day 3 was the maximum amounting to 4.2cm and 3.63cm in the group with the first estrus spontaneously induced and in the group with estrogens, respectively. The width of the PMSG group was at the peak of 3.57cm at day 4. No significant difference was observed between the width of valva at day 4 of each experimental group and those at day 5 of each of the experimental group, while that of the spontaneously induced initial estrus was the largest amoung other experimental groups.
