Effects of season and ovarian status on the outcome of long-term progesterone-based estrus synchronization protocols and ovulatory follicle development in Santa Inês ewes under subtropical conditions

Follicular wave emergence in Santa Inês ewes subjected to long-term, progesterone-based estrous synchronization protocols at different times of the year

“…Serum concentrations of P 4 in the present study were within the ranges observed during the course of CIDR-based estrous synchronization protocols in several previous studies (Oliveira et al, 2016). The replacement of CIDRs resulted in an increase in circulating concentrations of P 4 (>2 ng/mL) until the end of the treatment (Day 14), which eliminated the potential effects of low P 4 concentrations on antral follicular lifespan (Letelier et al, 2009;González-Bulnes et al, 2005).…”

Assessing the usefulness of B‐mode and colour Doppler sonography, and measurements of circulating progesterone concentrations for determining ovarian responses in superovulated ewes

“…This study was conducted in Jaboticabal, SP, Brazil (latitude: 21°15′18″S, longitude 48°19′19″W) from July to October (period of lengthening day lengths) and it utilized 24 sexually mature Santa Inês ewes, 2–3 years old, weighing 35–45 kg and kept under intensive management system with unlimited access to mineral salt licks, water and corn silage, and balanced feed rations (~200 g/animal/day). During the period of lengthening day lengths in southern Brazil, approximately 55% of Santa Inês ewes exhibit recurrent ovulatory cycles (Oliveira, Ayres, Oliveira, Barros, et al., ; Oliveira, Ayres, Oliveira, Oba, et al., ).…”

Evaluation of cervical mucus and reproductive efficiency of seasonally anovular dairy goats after short-term progestagen-based estrous induction protocols with different gonadotropins

“…The second experiment (Experiment 2) was conducted both in Piau, MG, Brazil as well as in the rural area of Florestal, MG, Brazil (latitude 19°53′S, longitude 44°25′W and altitude of 776 m). In such conditions, the breeding season (period of shortening daylengths) is from March to June, the non-breeding season (period of lengthening daylengths) is from August to November, and the transitional period (period of relatively stable long daylengths) is from December to February [15].…”

“…Clearly, the use of exogenous gonadotropins is necessary for estrous induction in the females that are in anoestrus due to lactation, nutritional status or seasonality. In southeastern Brazil, the vast majority of small ruminants are in anestrus at the time of the year in which this study was carried out (September to October; [15]). However, in the present study we did not confirm if all of the goats were anestrous prior to the commencement of presently tested estrous induction protocols; since it is possible that some females had been cycling, we consistently used the luteolytic doses of PGF2α in our synchronization protocols.…”

“…This may indicate that the majority of ovulations occur during the secretion of striated/caseous mucus, since the reduction in diameter of preovulatory follicles typically occurs just before follicle rupture (i.e. ovulation) in small ruminants [15].…”