201 research outputs found
The control of follicular dynamics by PGF2α, GnRH, hCG and oestrus synchronization in cattle
No full textProstaglandin F2alpha and control of reproduction in female swine: A review
No full textIn female swine, PGF2α is an important regulator of corpora luteal (CL) function, uterine contractility, ovulation, and embryo attachment. High affinity PGF2α receptors are present in the CL at all stages of the estrous cycle and they are functional. Therefore, a lack of luteolytic capacity of PGF2α is related to other factors that have not been well identified. In female pigs, a single exogenous PGF2α injection produces a short lasting decrease in plasma progesterone levels but does not induce luteolysis before day 12 of the estrous cycle. However, multiple injections of PGF2α can induce luteolysis before day 12 of the estrous cycle and may be utilized in the development of protocols for ovulation synchronization and timed AI. Most commonly, PGF2α is used for the induction of farrowing and so facilitation of cross fostering. Further, since PGF2α is a smooth muscle stimulant, treatment to stimulate myometrial contractions and uterine evacuation of residual products from parturition or infectious debris, may have beneficial effects on post-weaning fertility. Administration of PGF2α at the moment of insemination has been shown to improve reproductive performances when fertility is otherwise low, such as in sow under summer heat stress.F. De Rensis, R. Saleri, P. Tummaruk, M. Techakumphu, R.N. Kirkwoo
Protocols for synchronizing estrus and ovulation in buffalo (Bubalus bubalis): A review.
No full textPoor estrus expression and a prolonged intercalving interval compromise the reproductive efficiency of female buffaloes. These limitations are exacerbated during the hot season, when fertility decreases dramatically. Pregnancy rate decrease further because difficulties in detecting estrus. To improve reproductive efficiency, several protocols of estrus and ovulation synchronization have been developed. These procedures are based on manipulating the CL, either to induce premature luteolysis using prostaglandins or to prolong the luteal phase using progestagens. However, it has recently emerged that a more precise manipulation of follicular development may be needed to achieve better synchrony of ovulation and improve fertility. Researchers have therefore turned their attention to evaluating programs in which hormones such as GnRH, FSH, LH, eCG, hCG, prostaglandins, progesterone and estradiol are administered. This review considers the impacts of estrus and ovulation synchronization protocols on fertility in the buffalo. In general, it may be stated that buffaloes respond well to the exogenous administration of hormones, and artificial insemination is possible at a pre-established time after synchronizing ovulation. Most combined hormone protocols give satisfactory pregnancy rates, comparable to those achieved in animals inseminated at natural estrus
Effect of prior insemination of dead sperm and gestation housing management on gilt fertility
No full textDanbred gilts at about 120 kg were group housed for estrous detection. At detection of estrus, gilts either remained in pens (P) or were re-housed into individual gestation stalls (S) and were inseminated (DS), or not (SC), with a dose of frozen/thawed dead semen. Groups were P-DS (n = 81), P-SC (n = 70), S-DS (n = 98) and S-SC (n = 90). All gilts were inseminated with semen containing viable sperm at the second detected estrus and 24 h later. Pregnant gilts that were stall housed were moved to pens 35 d after insemination. There were no effects of insemination or housing management on farrowing rates or litter sizes
Conception rates following an Ovsynch and fixed-time insemination protocol with progesterone inclusion in cyclic dairy cows during the warm and cold seasons
No full textProgesterone plasma levels during the warm period of the year (summer) are more variable and this can induce a reduction in the fertility of dairy cows. Therefore, the aim of this study is to investigate the effect of the combined use of progesterone supplements with an Ovsynch and FTAI protocol on conception rates during the summer in cows. The data were compared with treatments carried out during the cold season (winter). In total, 120 cows underwent oestrus synchronization by using an Ovsynch and FTAI protocol. After this, one group of 60 cows received progesterone supplements and another group of 60 cows did not. In each group, 30 cows were treated during the summer and 30 cows were treated during the winter. All cows were pre-synchronized with PGF2α 25 days and 11 days before starting the Ovsynch protocol. The conception rate at days 30 and 40 post-insemination was not changed by the Ovsynch protocol being supplemented with progesterone. No interaction between progesterone supplementation and the season (winter or summer) was observed (P=0.17). The results of the study indicate that in cyclic cows with a functional corpus luteum the supplementation of the Ovsynch-FTAI protocol with progesterone did not improve the conception rate during the warm or cold seasons
Osservazioni preliminari sulla determinazione del progesterone nel latte di bovina nel periodo post-partum.
No full textControl of estrus in gilts and primiparous sows
No full textThe primary controller of weaned pig output is the successful breeding of enough females in the breeding week. The number of females available for breeding is dependent on the number of sows weaned sows and service ready gilt availability. Primiparous (P1) sows often have longer wean-estrus intervals (WEI) and increased anestrus; ensuring sufficient gilts and sows are available may require control of estrus. Stimulating estrus requires appropriate boar contact or when this is not sufficient, administration of gonadotrophins. If gonadotrophins are used expect estrus 4 to 6 d later and it is usual to breed at the induced estrus. If there is a problem of non-response the most likely cause is the females had a missed estrus are in their luteal phase. This can be resolved by feeding altrenogest for 18 d; expect cyclic animals to return 5 to 8 d later. The estrus response can be improved by gonadotrophin treatment at the end of altrenogest feeding. Female fertility is optimized by ensuring sperm deposition in the period 0 to 24 h before ovulation. This degree of accuracy may require control of ovulation by treatment with human chorionic gonadotrophin (ovulation 40-44 h later) or gonadotrophin releasing hormone (ovulation 36-40 h later). Knowing time of ovulation will allow use of other breeding technologies such as use of lower sperm numbers per dose and single inseminations
Control of estrus and ovulation: Fertility to timed insemination of gilts and sows
No full textAbstract
It is possible to control follicular development in gilts and sows with the use of hormones including the progestogen altrenogest, GnRH, eCG, hCG, and porcine luteinizing hormone (pLH). These hormones can be used to develop protocols for control of estrus with artificial insemination (AI) timed to estrus detection (timed artificial insemination; TAI) or to control estrus and ovulation with insemination at a fixed time without the requirement of estrus detection (fixed-timed artificial insemination; FTAI). In cyclic gilts, double TAI after protocols based on altrenogest and eCG plus hCG administration can achieve a 70% of farrowing rate. Valuable results can be obtained in weaned sows by the utilization of protocols based on eCG administration at weaning and then GnRH or pLH at estrus onset followed by single or double TAI. In cyclic gilts, single or double FTAI regardless of estrus expression can be applied after protocols based on altrenogest administration followed by eCG and then GnRH, hCG, or pLH some hours later; farrowing rates are similar to control animals inseminated at estrus detection. With sows, a protocol based on eCG administration at weaning and hCG, GnRH, or pLH some hours later followed by single or double FTAI can give fertility rates comparable to control animal inseminated at estrus. Most recently, injection or vaginal deposition of GnRH 96 hours after weaning followed by a single FTAI 24 to 30 hours later is resulting in reproductive performance not different to animals subject to multiple inseminations after natural estrus. It is possible to apply FTAI in lactating sows. The protocols are based on eCG during lactation followed by hCG and FTAI. These protocols will induce ovulation during lactation, but pregnancy rates are reduced. However, in the future, a better knowledge on the effect of hormone administration on follicular dynamics during lactation may allow the development of more effective protocols. © 2016 Elsevier Inc
Use of Equine Chorionic Gonadotropin to Control Reproduction of the Dairy Cow: A Review.
No full textEquine chorionic gonadotropin (eCG) is a member of the glycoprotein family of hormones along with LH, FSH and thyroid-stimulating hormone. In non-equid species, eCG shows high LH- and FSH-like activities and has a high affinity for both FSH and LH receptors in the ovaries. On the granulosa and thecal cells of the follicle, eCG has long-lasting LH- and FSH-like effects that stimulate oestradiol and progesterone secretion. Thus, eCG administration in dairy cattle results in fewer atretic follicles, the recruitment of more small follicles showing an elevated growth rate, the sustained growth of medium and large follicles and improved development of the dominant and pre-ovulatory follicle. In consequence, the quality of the ensuing CL is improved, and thereby progesterone secretion increased. Based on these characteristics, eCG treatment is utilized in veterinary medicine to control the reproductive activity of the cow by i) improving reproductive performance during early post-partum stages; ii) increasing ovulation and pregnancy rates in non-cyclic cows; iii) improving the conception rate in cows showing delayed ovulation; and finally, iv) eCG is currently included in protocols for fixed-time artificial insemination since after inducing the synchrony of ovulation using a progesterone-releasing device, eCG has beneficial effects on embryo development and survival. The above effects are not always observed in cyclic animals, but they are evident in animals in which LH secretion and ovarian activity are reduced or compromised, for instance, during the early post-partum period, under seasonal heat stress, in anoestrus animals or in animals with a low body condition score
Effect of duration of altrenogest treatment on farrowing rate and litter size of gilts
No full textThe objective of the present study was to compare two common durations of altrenogest (ALT) feeding during different periods of the year on the fertility of gilts after ALT withdrawal. During a 12-month period gilt replacements that were assumed to be cyclic were subjected to oestrus synchronisation with 15 mg/day ALT administered for 18 days (ALT-18; n = 268) or 14 days (ALT-14; n = 153) whereas 275 non-treated gilts served as controls. Fewer ALT-14 than ALT-18 gilts expressed oestrus by 7 days after last ALT treatment (79.1% vs 88.8%; P < 0.05). Farrowing rate was lower (P < 0.05) for ALT-14 than for the other groups (81%, 91% and 92% for ALT-14, ALT-18, and Control, respectively) but farrowing rates were not affected by time of year. Control litter sizes were not different from ALT-14 except during September to November when Control litter sizes were larger than either ALT treatments (13.6 ` 0.33, 12.3 ` 0.65 and 12.7 ` 0.39 for Control, ALT- 14 and ALT-18, respectively; P < 0.05). The ALT-18 gilts had larger litter sizes during January to August. The present data suggest that the appropriate duration of ALT feeding to synchronise oestrus in gilts is 18 days
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