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

This study was conducted to document the pattern of antral follicular wave emergence throughout the 14-day, progesterone (P4)-based estrous synchronization protocol in ewes that were maintained in subtropical conditions, during the period of increasing day lengths (ID), decreasing day lengths (DD), and the transitional period (TP). In addition, the influence of ovarian status (i.e., size of ovarian antral follicles and the presence of corpora lutea) at the outset of P4 treatment on ensuing ovarian follicular wave development was examined. Sexually mature Santa Inês ewes (n=70) were subjected to one of the two estrous synchronization protocols in the three seasons. On Day 0, the ewes received an i.m. injection of prostaglandin F2α and an intravaginal P4-releasing device that remained in place for 14days (G-1CIDR) or was replaced on Day 7 (G-2CIDR). Daily ultrasonography of ovaries was conducted from Days 0 to 15. Mean (±SEM) numbers of follicular waves per ewe were 3.7±0.1 and 3.6±0.1 for G-1CIDR and G-2CIDR (P>0.05). The number of emerging follicular waves was greater (P<0.05) during the ID period than during the TP and DD periods (4.0±0.1, 3.4±0.1 and 3.6±0.1, respectively). The presence of medium-sized antral follicles (4.0 to 5.75mm) in the absence of corpora lutea at the time of CIDR insertion tended to advance follicular wave emergence. Although the long-term P4 treatment was not originally designed to synchronize follicular waves, there was a distinctive pattern of follicular wave dynamics during the period of application of CIDRs that was affected mainly by the number of emerging follicular waves and ovarian status at CIDR insertion.

Are pharmacological interventions between conception and birth effective in improving reproductive outcomes in North American swine?

The objective of this review is to evaluate the effectiveness of using pharmacological compounds on reproductive outcomes, particularly litter size, in North American swine. While the opportunity to improve reproduction in North American pigs exists, numerous hurdles need to be overcome in order to achieve measureable results. In the swine industry, the majority of piglet losses are incurred during pregnancy and around farrowing. Over the last 20 years, a reduction in losses has been achieved through genetic selection and nutritional management; however, these topics are the focus of other reviews. This review will evaluate attempts to improve litter size by reducing losses at various stages of the reproductive process, from the time of conception to the time of farrowing, using pharmacological compounds. Generally, these compounds are used to either alter physiological processes related to fertilization, embryonic attachment or uterine capacity, etc., or to facilitate management aspects of the breeding females such as inducing parturition. Although some of the pharmacological agents reviewed here show some positive effects on improving reproductive parameters, the inconsistent results and associated risks usually outweigh the benefits gained. Thus, at the present time, the use of pharmacological agents to enhance reproduction in North American swine may only be recommended for herds with low fertility and presents an avenue of research that could be further explored.

Estrus synchronization in sheep and goats using combinations of GnRH, progestagen and prostaglandin F2alpha.

The objective of this experiment was to evaluate the effect of GnRH, progestagen and prostaglandin F(2alpha) on estrus synchronization in sheep and goats. Sixty Awassi ewes and 53 Damascus does were used in the study. The experiment started at the beginning of the breeding season (June/July). The same treatments were applied to sheep and goats as follows: no treatment (CON), 14-day progestagen sponges and 600 IU equine chorionic gonadotropin (S), gonadotropin releasing hormone followed 5 days later by prostaglandin F(2alpha) (GP) and gonadotropin releasing hormone, progestagen sponges for 5 days and prostaglandin F(2alpha) on the day of sponge removal (GSP). None of the ewes in the S group lambed from mating during the induced cycle. A greater lambing rate (p < 0.05) was observed in the GSP group compared with the CON and S groups while the GP group was intermediate. The number of lambs born per lambed ewe was similar among the CON, GP and GSP groups. However, the number of lambs per exposed ewe was greater (p < 0.05) in the GSP than the remaining groups. The induced cycle kidding rate was 77% for all treatments combined. Similar kidding rate were observed among treatments. The numbers of kids born per kidded and exposed doe from mating during the induced estrus were also similar among treatments. Greater numbers of multiple births were observed in the GP and GSP than in the S group. In conclusion, a combination of GnRH, progestagen sponges and PGF(2alpha) can be effective in synchronizing estrus and improving fecundity in sheep and goats. Although the use of GnRH-PGF(2alpha) was effective, the addition of progestagen sponges at the time of GnRH administration appeared to improve reproductive parameters.

Sexual performance of rams sequentially exposed to short-tailed and fat-tailed ewes.

The objective of the study was to compare sexual performance of pure and crossbred rams, and to evaluate whether prior exposure of rams to short-tailed females would enhance their mating ability when later exposed to fat-tailed females. Twenty-two virgin, yearling Awassi (A; n = 7), F(1) Charollais x Awassi (CA; n = 7) and F(1) Romanov x Awassi (RA; n = 8) rams were subjected to sexual performance tests on six 20-min occasions. Each ram was individually exposed to two short-tailed oestrous ewes for three 20-min occasions on three consecutive days. Following 1 day of rest, the same 3-day procedure was repeated for each ram with fat-tailed ewes. Leg kicking bout frequency increased in CA and RA rams and decreased in A rams, when they were exposed to fat-tailed compared with short-tailed ewes. No differences in anogenital sniffing were observed among rams exposed to either short-tailed or fat-tailed ewes. However, greater (p < 0.001) anogenital sniffing bouts were recorded, when rams were exposed to short-tailed females. Upon exposure to fat-tailed ewes, CA and RA rams experienced a marked increase in mounting frequency compared with a slight increase in mounting of A rams (p < 0.001). The ability of Awassi rams to raise the fat tail of Awassi ewes was greater (p < 0.001) than CA and RA rams. Mating was improved in A while declining in CA and RA, when they were exposed to fat-tailed compared with short-tailed ewes (p < 0.001). Based on the results of the current study, it seems that all yearling rams were capable of mating with short-tailed ewes, whereas only Awassi rams managed to mate with fat-tailed ewes. It appears that brief exposures of yearling crossbred rams to short-tailed ewes do not improve their mating ability when later exposed to fat-tailed ewes.

Sexual behaviour of yearling Awassi, Charollais x Awassi and Romanov x Awassi rams exposed to oestrous Awassi ewes.

This study was conducted to evaluate the sexual performance of 10-month-old, ram lambs of different breed groups. Eight ram lambs each of Awassi (A), F1 CharollaisxAwassi (CA) and F1 RomanovxAwassi (RA) breed types were subjected to sexual performance tests by being individually exposed to two oestrous Awassi ewe lambs for four 20-min periods. Bouts of leg kicking and anogenital sniffing were similar among breed groups. Mounting frequency was greater (p<0.05) in RA than in A and CA ram lambs. Tail-raising was greater (p<0.05) and mating rate tended to be greater (p<0.10) in A than in RA and CA ram lambs. The number of mounts per tail-raising (efficiency) was influenced by breed group and test day (p<0.05). Awassi ram lambs maintained the best efficiency throughout the experiment. Efficiency in RA and CA ram lambs improved with each test day. Results of the present study indicate that RA ram lambs have greater mounting frequency than A and CA, while Awassi are more capable of mating with fat-tailed females than the CA and RA ram lambs.

Reproductive responses in ewes treated with eCG or increasing doses of royal jelly.

This experiment was conducted to evaluate the effect of administering increasing doses of royal jelly (RJ) on reproductive parameters in ewes. Additionally, this study compared using RJ vs. equine chorionic gonadotropin (eCG) in estrous cycle control. In May (transitional period between anestrous and the breeding season) 37 multiparous, winter-lambing Awassi ewes 3-6 years of age (average body weight of 53+/-1.2 kg) were fitted with intravaginal flourogestone acetate-impregnated sponges (FGA, 40 mg) for 12 days. Ewes were randomly assigned into five treatment groups to receive no RJ (CON, n=7), 250 mg RJ/d (RJ250, n=8), 500 mg RJ/d (RJ500, n=8), 750 mg RJ/d (RJ750, n=7), or 600IU eCG (eCG, n=7). Royal jelly was administrated orally on daily basis when sponges were in place while eCG was administered on the day of sponge withdrawal (d 0). Behavioral estrus was checked using fertile Awassi rams at 6h intervals for 5 days beginning on d 1. Interval from d 0 to onset of estrus was shorter (P<0.05) in eCG than in CON and RJ250 groups. No differences in the onset of estrus were detected among the RJ-treated groups. The intervals from d 0 to first progesterone rise were shorter (P<0.05) in the eCG-treated compared with RJ-treated and control ewes (100+/-15.3, 138.4+/-14, 135.7+/-15, 155.6+/-15, 154.4+/-15.1h in eCG, CON, RJ250, RJ500, and RJ750, groups, respectively). The overall pregnancy rate from mating at induced estrus was 75.7% (28/37). Of these ewes, 23/37 (64.8%) lambed within 155 days following d 0. Lambing rate was higher (P<0.05) in the RJ500 group compared with controls. Lambing rate from mating at induced estrus was 2/7 (28.5%), 4/8 (50%), 8/8 (100%), 4/7 (57%), and 5/7 (71%) in CON, RJ250, RJ500, RJ750, and eCG groups, respectively. Results of the present study demonstrate that eCG but not RJ was effective in improving estrus expression in ewes during the transition between the non-breeding and breeding seasons. Royal jelly may be effective in improving pregnancy and lambing rates but further studies are required to confirm such findings.

Effect of progesterone prior to GnRH-PGF2alpha treatment on induction of oestrus and pregnancy in anoestrous Awassi ewes.

An experiment was conducted to examine the effect of progesterone prior to a GnRH-PGF2alpha treatment on oestrus and pregnancy in seasonally anoestrous Awassi ewes. Twenty-four ewes were randomly assigned to three groups to be pre-treated with 60 mg medroxyprogesterone acetate sponges (group A), 600 mg progesterone sponges (group B) or blank sponges (group C) for 4 days. All ewes were injected with 100 microg of GnRH 24 h after sponge removal followed, 5 days later, by 20 mg PGF2alpha injection. Ewes were exposed to three fertile rams at the time of PGF2alpha injection (day 0, 0 h) and were checked for breeding marks at 6-h intervals for 5 days. Blood samples were collected from all ewes 1 day (day -10) prior to sponge insertion, at the time of sponge removal (day -6), 1 day following sponge removal (day -5, at the time of GnRH injection) and at the time of PGF2alpha injection (day 0) for analysis of progesterone. Progesterone concentrations on days -10 and -5 were basal and averaged 0.2 +/- 0.04 and 0.2 +/- 0.2 ng/ml, respectively. Progesterone concentrations on day -6 were elevated only in group B ewes and were higher (p < 0.0001) than those of groups A and C. Progesterone concentrations on day 0 were higher (p = 0.002) in groups A and B than group C. Oestrous responses occurred only in ewes of groups A and B (p > 0.05). Induced oestrus conception rate was greater (p < 0.01) in group A than groups B and C. Ewes returned to oestrus 17-20 days following day 0 were two of eight, six of eight and three of eight of groups A, B and C, respectively, all of which eventually lambed. The overall lambing rate was 82% in progesterone-primed ewes compared with only 38% non-progesterone-primed ewes (p < 0.05). Progesterone priming apparently sensitizes GnRH-PGF2alpha-treated seasonally anoestrous ewes and increases their response in oestrus and pregnancy rates.

Reproductive responses following royal jelly treatment administered orally or intramuscularly into progesterone-treated Awassi ewes.

An experiment was conducted to determine whether natural royal jelly (RJ) paste administered orally or intramuscularly (i.m.) in conjunction with exogenous progesterone is associated with improved reproductive responses in ewes. Thirty 3-6-year-old Awassi ewes were randomly allocated into three (RJ-capsule, RJC; RJ-injection, RJI and control, CON) groups of 10 ewes each. All ewes were treated with intravaginal progesterone sponges for 12 days. Ewes in the RJC and RJI were administered orally or i.m. with a total of 3g of RJ given in 12 equal doses of 250 mg per ewe per day starting at the time of sponge insertion. At the time of sponge withdrawal (day 0, 0 h), ewes were exposed to three rams and checked for breeding marks at 6-h intervals for 3 days. Blood samples were collected from all ewes for analysis of progesterone concentrations. Pretreatment progesterone levels were <0.5 ng x ml(-1) in 16/30 and >1.3 ng x ml(-1) in the remaining ewes indicating luteal function and cyclicity. Similar reproductive responses and progesterone levels occurred in ewes of the RJC and RJI; therefore, data of the two groups were pooled. Following sponge insertion, progesterone levels increased rapidly and reached maximum values of 5.8+/-0.2 ng x ml(-1) within 2 days among ewes of the three groups, and then declined gradually to day 0 values of 1.6+/-0.1 and 1.9+/-0.1 ng x ml(-1) for the RJ-treated and CON ewes, respectively. The rate of progesterone decline was greater (P<0.001) in RJ-treated than in CON. Mean progesterone levels during the 12-day period were lower (P<0.001) in RJ-treated than in CON (2.8+/-0.2 ng x ml(-1) versus 3.3+/-0.2 ng x ml(-1)). Treatment with RJ resulted in greater (P<0.05) incidence of oestrus and shorter (P<0.05) intervals to onset of oestrus than CON. Based upon progesterone levels, ovulation occurred following day 0 in all ewes. Progesterone increased on day 3 in RJ-treated and on day 4 in CON ewes. Progesterone remained elevated through day 18 in 8/20 RJ-treated and 1/10 CON ewes (P=0.09). All pregnant ewes exhibited oestrus 14 h earlier (P<0.02), ovulated approximately 1 day earlier and had higher (P<0.001) luteal phase progesterone levels than non-pregnant ewes. Non-pregnant had higher (P<0.04) body weights than pregnant ewes. In conclusion, results demonstrate that both RJ treatments in conjunction with exogenous progesterone were equally capable of improving oestrus response and pregnancy rate.

Luteinizing hormone and ovarian response of early postpartum Debouillet ewes treated with cyproheptadine and(or) melatonin.

Two trials were conducted to evaluate the effects of cyproheptadine (serotonin receptor antagonist, Trial 1) along with administering melatonin (Trial 2) to early postpartum (PP) ewes on LH profiles and follicular development. In Trial 1, 12 mature ewes received either control (CON) or cyproheptadine (CYP) treatments (six ewes/treatment). Beginning on d 5 PP, each ewe received i.v. either 0 (vehicle) or .1 mg of CYP/kg BW twice daily for 5 d. Cyproheptadine tended to stimulate (P < .10) release of LH on d 5 PP (1.3 and .8 +/- .2 ng LH/mL for CYP-treated and CON ewes, respectively) with a similar trend (P < .10) of LH release occurring on d 9. Cyproheptadine also had a positive effect on follicular development, but no luteal activity was detected. In Trial 2, 16 mature ewes received CON, i.v. CYP (.1 mg/kg BW twice daily), i.m. melatonin (MEL, 5 mg x ewe(-1) x d(-1)), or CYP+MEL. Treatments were administered from d 5 through 14 PP. Cyproheptadine tended to increase (P < .10) LH pulsatility on d 5 and 14, but MEL had no effect (P > .20). Follicular development was not affected (P > .40) by CYP or MEL treatments. Neither MEL nor CYP affected progesterone (P > .60). Cyproheptadine tended to increase LH concentration and pulse frequency in early PP ewes, but MEL had no effect on LH profiles. Both treatments failed to initiate ovarian cyclicity in early PP ewes.

Effects of locoweed (Oxytropis sericea) on growth, reproduction, and serum hormone profiles in young rams.

Sixteen ram lambs (5 mo old, average BW = 49 +/- 1.4 kg) received a control diet (50% concentrate, 13.1% CP) or a diet containing 7, 14, or 21% locoweed (LW, DM basis). Rams were housed in individual pens (2.5 x 3.5 m) in an enclosed facility (14 h light, 10 h dark) with free access to feed and water. After 35 d of LW feeding, rams fed the 21% LW diet ate 1.3 to 1.6 kg/d, whereas rams fed the other three diets ate 1.6 to 2.0 kg/d. On d 35, BW (mean +/- SE) were 58.3, 57.2, 57.2, and 55.4 (+/- 1.5 kg/d) for ram lambs receiving 0, 7, 14, and 21% LW, respectively (P > .20). An inverse relationship for BW (P < .10) and gain (P = .04) was observed 1 mo after LW feeding ended relative to amount of LW in the diet. Serum alkaline phosphatase increased with increasing LW (P < .05), and thyroxine concentration was decreased (P < .05) by LW ingestion. On d 35, serum LH averaged 6.8, 9.9, 11.6, and 9.9 (+/- 1.8) ng/mL (P = .56), whereas testosterone averaged 3.5, 2.6, 3.0, and 1.6 (+/- .5) ng/mL (linear effect of LW, P = .05) over a 5-h period after GnRH injection (i.m., 50 microg) in lambs fed 0, 7, 14, and 21% locoweed, respectively. Semen volume, sperm motility, sperm cell concentration, and percentage of abnormal cells did not differ (P > .50) on d 35. One month after the end of LW feeding, a linear (P = .06) decrease in sperm motility and scrotal circumference was observed relative to percentage of prior dietary LW. These data suggest that LW exerts adverse effects on the testes of young rams that may not be evident until several weeks after LW consumption ends.