Presynchronizing PGF2α and GnRH injections before timed artificial insemination CO-Synch + CIDR program

Fixed-time artificial insemination is an effective management tool that reduces the labor associated with more conventional artificial insemination programs requiring detection of estrus. The 7-day CO-Synch + controlled internal drug release (CIDR) insert protocol has been shown to effectively initiate estrus and ovulation in cycling and non-cycling suckled beef cows, producing pregnancy rates at or greater than 50% in beef cows. The gonadotropin-releasing hormone (GnRH) injection that begins the CO-Synch + CIDR program initiates ovulation in a large proportion of cows, particularly anestrous cows. The CIDR, which releases progesterone intravaginally, prevents short estrous cycles that usually follow the first postpartum ovulation in beef cows. Our hypothesis was that inducing estrus with a prostaglandin injection followed 3 days later with a GnRH injection, 7 days before applying the 7-day CO-Synch + CIDR protocol, might increase the percentage of cycling cows that would exhibit synchronous follicular waves after the onset of the CO-Synch + CIDR protocol. We also hypothesized that the additional GnRH injection would increase the percentage of anestrous cows that would ovulate, thereby increasing pregnancy outcomes

The Mare Model to Study the Effects of Ovarian Dynamics on Preantral Follicle Features.

Ovarian tissue collected by biopsy procedures allows the performance of many studies with clinical applications in the field of female fertility preservation. The aim of the present study was to investigate the influence of reproductive phase (anestrous vs. diestrous) and ovarian structures (antral follicles and corpus luteum) on the quality, class distribution, number, and density of preantral follicles, and stromal cell density. Ovarian fragments were harvested by biopsy pick-up procedures from mares and submitted to histological analysis. The mean preantral follicle and ovarian stromal cell densities were greater in the diestrous phase and a positive correlation of stromal cell density with the number and density of preantral follicles was observed. The mean area (mm2) of ovarian structures increased in the diestrous phase and had positive correlations with number of preantral follicles, follicle density, and stromal cell density. Biopsy fragments collected from ovaries containing an active corpus luteum had a higher follicle density, stromal cell density, and proportion of normal preantral follicles. In conclusion, our results showed: (1) the diestrous phase influenced positively the preantral follicle quality, class distribution, and follicle and stromal cell densities; (2) the area of ovarian structures was positively correlated with the follicle and stromal cell densities; and (3) the presence of an active corpus luteum had a positive effect on the quality of preantral follicles, and follicle and stromal densities. Therefore, herein we demonstrate that the presence of key ovarian structures favors the harvest of ovarian fragments containing an appropriate number of healthy preantral follicles

The "ram effect": new insights into neural modulation of the gonadotropic axis by male odors and socio-sexual interactions

Reproduction in mammals is controlled by the hypothalamo-pituitary-gonadal (HPG) axis under the influence of external and internal factors such as photoperiod, stress, nutrition, and social interactions. Sheep are seasonal breeders and stop mating when day length is increasing (anestrus). However, interactions with a sexually active ram during this period can override the steroid negative feedback responsible for the anoestrus state, stimulate LH secretion and eventually reinstate cyclicity. This is known as the ram effect and research into the mechanisms underlying it is shedding new light on HPG axis regulation. The first step in the ram effect is increased LH pulsatile secretion in anestrus ewes exposed to a sexually active male or only to its fleece, the latter finding indicating a pheromone-like effect. Estradiol secretion increases in all ewes and this eventually induces a LH surge and ovulation, just as during the breeding season. An exception is a minority of ewes that exhibit a precocious LH surge (within 4h) with no prior increase in estradiol. The main olfactory system and the cortical nucleus of the amygdala are critical brain structures in mediating the ram effect since it is blocked by their inactivation. Sexual experience is also important since activation (increased c-fos expression) in these and other regions is greatly reduced in sexually naïve ewes. In adult ewes kisspeptin neurons in both arcuate and preoptic regions and some preoptic GnRH neurons are activated 2h after exposure to a ram. Exposure to rams also activates noradrenergic neurons in the locus coeruleus and A1 nucleus and increased noradrenalin release occurs in the posterior preoptic area. Pharmacological modulation of this system modifies LH secretion in response to the male or his odor. Together these results show that the ram effect can be a fruitful model to promote both a better understanding of the neural and hormonal regulation of the HPG axis in general and also the spe

Učinak hromosti na folikularnu dinamiku u postpartalnom razdoblju u anestričnih križanih krava

Lameness affects the reproductive performance of cows. It is not clear whether follicular dynamics is involved. Ovarian ultrasonography was performed once daily in eight non - lame (N) and 11 lame (L) cows for a period of 30 days each. Recurrent follicular waves could be detected every 8.3 ± 0.4 and 7.6 ± 0.5 days, respectively, in the N and L cows. There were no appreciable differences in the day of selection (Day 2.3 ± 0.2 versus Day 2.8 ± 0.2), maximum diameters (8.9 ± 0.6 mm versus 9.2 ± 0.5 mm) and certain characteristics pertaining to growth, static and regression of the dominant follicles (DFs) in the N versus the L cows. The L cows, however, had a tendency to have a higher number (P3≤5 mm). In conclusion, lameness did not affect the DFs that developed but failed to ovulate, but more the number of small follicles, both identifi ed and unidentifi ed, hints at some perturbance in the follicular characteristics of lame cows that needs to be addressed in the light of the mechanisms governing follicular dynamics.Hromost utječe na reprodukcijsku sposobnost krava, ali nije sa sigurnošću ustanovljeno utječe li i na folikularnu dinamiku. Jajnici osam normalnih i 11 hromih krava ultrazvučno su bili pregledavani jednom dnevno u razdoblju od 30 dana. Povratni folikularni valovi mogli su se ustanoviti svakih 8,3 ± 0,4 u normalnih i 7,6 ± 0,5 dana u hromih krava. Nisu bile ustanovljene znatne razlike u selekciji (dan 2,3 ± 0,2 u normalnih, 2,8 ± 0,2 u hromih), najvećem promjeru (8,9 ± 0,6 mm u normalnih, 9,2 ± 0,5 mm u hromih) određenim značajkama rasta, postojanosti i regresije dominantnih folikula u normalnih u odnosu na hrome krave. Međutim hrome krave pokazivale su tendenciju većeg broja (P3≤5 mm). Zaključuje se da hromost nije utjecala na dominantne folikule koji su se razvili, a nisu ovulirali, ali veći broj malih folikula, identifi ciranih i neidentifi ciranih, upućuje na neke smetnje folikularnih značajki u hromih krava koje se moraju uzeti u obzir u svjetlu mehanizma što upravlja folikularnom dinamikom

Relation Between Oxidant/Antioxidant Status and Postpartum Anestrous Conditions

The aim of the present study was to detect the relation between oxidant/antioxidant status and postpartum anestrous (PPA) conditions in dairy cows.The postpartum period is a very critical time that influenced mainly in cattle reproduction. A little information is obtainable in literature concerning antioxidant defense mechanisms during anestrus.The purpose of the following study is detection of the relation between oxidant/antioxidant status and postpartum anestrous (PPA) condition in dairy cows. Seventy five postpartum anestrous (PPA) and twenty five normal cyclic Holstein Friesian pluriparous dairy cows were selected on the basis of their reproductive history gained from farm records. Depend on the rectal findings and ultrasonography in addition to progesterone profile the studied animals were classified into three groups (each 25 animals) as inactive ovaries group, persistent corpus luteum group and silent heat group. Blood samples from anestrous and normal cyclic animals were gathered at day 0, day 10, day 21. These samples were utilized for detection of MDA, Vitamin C, Nitric Oxide and Total antioxidant capacity. Results of the present study revealed that MDA and Nitric Oxide were be significantly (plt0.05) higher in the groups of PPA than the normal cyclic group. Vitamin C (Ascorbic acid)nbsp levels were seen to be significantly (plt0.05) lower in normal cyclic animals in comparison to inactive ovaries group and persistent C.L group ,while there is no significant difference with the silent heat group . No statistically significant difference was detected in the total antioxidant capacity between the group of silent heat and the normal cyclic group, while the groups of persistent C.L and inactive ovaries were found to have statistically significant difference (plt0.05) with the normal cyclic group. It is concluded that supplementing diets with optimal levels of micronutrients with antioxidant capabilities is a good advice to farmers to avoid post-partum anestrum. Moreover, early approaches to conflict the progression of stress and to promote the antioxidant defense mechanisms of dairy cattle during times of increased metabolic demands appears to be Pertinent

Reproductive management in pigs: emphasis on the different roles of the boar and on optimal insemination management

Boars have different roles in the reproductive management in pigs. Boar contact can stimulate follicle development and thereby induce oestrus, both in gilts and sows. Boar contact during oestrus is essential for good oestrus expression, which is essential for the correct timing of insemination and the proper use of boar contact during insemination can stimulate sperm transport and thereby fertilisation. Stimulation by boars clearly has an olfactory component (the boar smell), but can also have an auditory, visual and evn tactile component. The background of the different roles and some of these different components of the boar are discussed. To enable a good farrowing rate and litter size, sows should be inseminated between 0 and 24h before ovulation. However, it is not possible to accurately predict the time of ovulation in sows. Although ovulation takes place at a relatively fixed 60-75% of the duration of oestrus, the duration of oestrus varies considerably between sows and between farms, resulting in a variable ovulation time from onset of oestrus. Therefore, most farmers inseminate their sows every day of oestrus to ensure insemination within the optimal period. Since post-ovulation inseminations should be avoided, it is adviced to only inseminate sows while they still show an optimal standing respons

Efficacy of Various Five-Day Estrous Synchronization Protocols in Sheep

The objective of this study was to determine the effects of various estrous synchronization protocols utilizing the five-day controlled internal drug releasing (CIDR) inserts that are infused with progesterone (P4) alone and when coupled with gonadotropin-releasing hormone (GnRH) and prostaglandin (PG) during different breeding seasons. Ewes received either 1 of 4 treatments: 1) Untreated (U); 2) 5 d CIDR (0.3 g P4) insert (C); 3) 5 d CIDR and PG at CIDR removal (d 0, P); or 4) GnRH at 5 d CIDR insertion and PG at CIDR removal (G). In Experiment 1, overall days to estrus were greater (P ≤ 0.01) in U and P compared with C. In Experiment 2, overall days to estrus were greater (P ≤ 0.02) in U and P compared with G. In summary, the 5 d CIDR reduces the number of days required to bring ewes into estrus when compared to untreated ewes

Altered progesterone concentrations by hormonal manipulations before a fixed-time artificial insemination CO-Synch + CIDR program in suckled beef cows

We hypothesized that pregnancy outcomes may be improved by inducing luteal regression, ovulation, or both (i.e., altering progesterone status) before initiating a timed–artificial insemination (TAI) program in suckled beef cows. This hypothesis was tested in two experiments in which cows were treated with either PGF[subscript 2α] (PG) or PG + GnRH before initiating a TAI program to increase the proportion of cows starting the program in a theoretical marginal (<1 ng/mL; experiment 1) or elevated (≥1 ng/mL; experiment 2) progesterone environment, respectively. The control was a standard CO-Synch + controlled internal drug release (CIDR) program employed in suckled beef cows (100 μg GnRH intramuscularly [IM] [GnRH-1] and insertion of a progesterone-impregnated intravaginal CIDR insert on study Day −10, 25 mg PG and CIDR insert removal on study Day −3, and 100 μg GnRH IM [GnRH-2] and TAI on study Day 0). In both experiments, blood was collected before each injection for later progesterone analyses. In experiment 1, cows at nine locations (n = 1537) were assigned to either: (1) control or (2) PrePG (same as control with a PG injection on study Day −13). The PrePG cows had larger (P < 0.05) follicles on study Day −10 and more (P < 0.05) ovulated after GnRH-1 compared with control cows (60.6% vs. 36.5%), but pregnancy per TAI was not altered (55.5% vs. 52.2%, respectively). In experiment 2, cows (n = 803) at four locations were assigned to: (1) control or (2) PrePGG (same as control with PG injection on study Day −20 and GnRH injection on study Day −17). Although pregnancy per TAI did not differ between control and PrePGG cows (44.0% vs. 44.4%, respectively), cows with body condition score greater than 5.0 or 77 or more days postpartum at TAI were more (P < 0.05) likely to become pregnant than thinner cows or those with fewer days postpartum. Presynchronized cows in both experiments were more (P < 0.05) likely than controls to have luteolysis after initial PG injections and reduced (P < 0.05) serum progesterone; moreover, treatments altered the proportion of cows and pregnancy per TAI of cows in various progesterone categories before the onset of the TAI protocol. In combined data from both experiments, cows classified as anestrous before the study but with elevated progesterone on Day −10 had increased (P < 0.05) pregnancy outcomes compared with anestrous cows with low progesterone concentrations. Progesterone concentration had no effect on pregnancy outcome of cycling cows. In summary, luteal regression and ovulation were enhanced and progesterone concentrations were altered by presynchronization treatments before the 7-day CO-Synch + CIDR program, but pregnancy per TAI was not improved

Effects of a Gonadotropin Mixture on Reproductive Success in Progesterone- Treated Non-Lactating Anestrous Ewes

Using exogenous gonadotropins as part of an estrous induction protocol can have beneficial effects on fertility in ewes bred out-of-season. Few studies have evaluated the efficacy of P.G. 600RTM, a mixture of gonadotropins with FSH-like and LH-like activity, to increase fertility in anestrous ewes and, in particular, following pre-treatment with progesterone delivered via controlled internal drug releasing (CIDR) devices. The objective of this study was to evaluate the effects of P.G. 600RTM on reproductive success in progesterone-treated non-lactating anestrous ewes. Ewes, which had been separated from rams for at least one month prior to the beginning of the experiment, received CIDR inserts five days prior to introduction of rams. In the first experiment, ewes were assigned randomly to receive either a 3 mL injection of P.G. 600RTM [i.m., 240 IU equine chorionic gonadotropin (eCG) and 120 IU human chorionic gonadotropin (hCG)] at CIDR insert removal or no further treatment. In the second experiment, ewes were assigned randomly to receive either a 3 mL injection of P.G. 600RTM one day prior to insert removal or no further treatment. In experiment 1, incidence of estrus was significantly greater for treated ewes than control ewes, while prolificacy (number of lambs born per ewe lambing) tended to be higher in treated ewes. In experiment 2, treated ewes had significantly higher conception rates and pregnancy rates to first service and tended to have higher overall pregnancy rates than control ewes. A greater percentage of ewes lambed in the treated group than in the control group; however, prolificacy was not different between the groups. In addition, overall lambing rates in ewes treated with P.G. 600RTM were significantly higher than those of the control group. An injection of 3 mL of P.G. 600RTM (240 IU eCG and 120 IU hCG) one day prior to CIDR removal significantly increased reproductive success in progesteronetreated non-lactating anestrous ewes. Further, the gonadotropin injection was determined to be economically beneficial

Induction of fertile estrus during seasonal anestrus in ewes and fall born ewe lambs

The quantity of progesterone (P4) delivered by a new P 4 releasing intravaginal insert (polycapralactone [PCL] insert), was inadequate to increase serum concentrations of P4 to that observed in cycling ewes during the luteal phase. Percentage of ewes in estrus was greater in P4 treated than in control ewes. Estrous response was greater after treatment with P4 for 5 than for 12 d. Progesterone increased the percentage of ewes lambing to both service periods by 20 percentage points. Prolificacy to the first service period in ewes treated with FSH was greater than the prolificacy in control and all ewes lambing to the second service period. Treatment with P4 for 5 d was as effective as for 12 d to induce fertile estrus in FSH-treated anestrous ewes.;In the second experiment, a 5 d pre-treatment with P4 prior to ram introduction induced estrus in anestrous ewes. The estrous response varied quadratically with time after ram introduction, and the conception rate varied quadratically with the time of observation of onset of estrus. Progesterone treatment increased the percentage of ewes lambing and the number of lambs born per ewe exposed over that observed in ewes introduced to rams alone. Prolificacy to the first service tended to be greater in FSH treated ewes than in ewes receiving P4 alone and all ewes lambing to the second service period.;In the third experiment, ram introduction by itself but not P4 pre-treatment alone induced an increase in LH secretion, follicular development, an LH surge and ovulation in fall-born ewe lambs. Progesterone delayed the RI LH surge, an effect that was prevented by the administration of estrogen 24h after P4 withdrawal. Progesterone pre-treatment for 5 days prior to ram introduction resulted in the expression of estrous behavior in a small percentage of fall-born ewe lambs. Estrogen increased the percentage of P4 pre-treated ewes displaying estrus. Poor reproductive performance of fall-born ewe lambs treated with P4 and exposed to rams during anestrus is not due to the inability of rams to induce ovulation but may be related to a reduced secretion of or sensitivity of behavioral centers to estrogen