Effect of acute bull exposure around the time of artificial insemination on serum oxytocin and progesterone concentrations and pregnancy rates in dairy cows.

This study examined the effect of acute bull exposure around the time of artificial insemination (AI) on oxytocin and progesterone concentrations, and pregnancy rates in dairy cows. Ninety six dairy cows, stratified according to parity into primiparous and pluriparous, were divided into three groups; short bull exposure (SBE; 10 min, n = 32), long bull exposure (LBE; 4 h, n = 32) or no bull exposure (NBE; n = 32). On day 45 post-partum, all cows were treated with PGF2α on three occasions 11-14 days apart to synchronize oestrus. They were submitted to fixed time AI 80 h after the third PGF2α injection. Cows in the SBE and LBE groups were artificially inseminated 5 min after the introduction of the bull. From a subset of cows (n = 6 per group; three primiparous and three pluriparous), blood samples were collected once every 5 min starting 15 min before AI until 15 min after AI and analysed for oxytocin concentrations. Additional blood samples were collected for measurements of progesterone (P4) concentrations once daily for 4 days starting on the day of AI and once every 3 days thereafter until day 22. The effects of bull exposure, time, parity, difficulty of AI, and pregnancy on oxytocin and P4 concentrations were analysed using the mixed linear model procedure. Mean oxytocin concentrations or change in oxytocin concentrations after bull exposure or AI were not different among groups. Pregnancy rates for the NBE, SBE and LBE groups were 55.5%, 33.3% and 44.4%, respectively, and were not different among groups. In conclusion, acute bull exposure around the time of AI did not affect oxytocin and progesterone concentrations and did not improve pregnancy rates in dairy cattle under these farms conditions.

A new strategy for superior reproductive performance of ewes bred out-of-season utilizing progestagen supplement prior to withdrawal of intravaginal pessaries.

Two experiments were conducted to examine the effect of progestagen supplement 24h prior to intravaginal pessary withdrawal on reproductive performance of seasonal anestrous ewes. Ewes in each experiment were allocated to treatment and control and all were induced to estrus using either intravaginal MAP (Exp. 1; n=24) or CIDR-G (Exp. 2; n=28) pessaries for 12 days. Half of the ewes in each experiment were supplemented 24h before withdrawal of pessaries with either 10mg oral MAP tablets (Exp. 1) or 25mg i.m. progesterone (P(4)) administration (Exp. 2; P(4)-supplement-treated group). Fertile rams were allowed with the ewes at sponge removal (Day 0, 0h) and estrus was monitored at 6-h intervals for 3 days. Blood samples were collected for measurements of P(4) (Exp. 1 and Exp. 2) and LH (Exp. 2). In both experiments, the percent of ewes in estrus was greater (P<0.05) and intervals to estrus were longer (P<0.05) in progestagen-supplement-treated than control ewes. In Exp. 2, the occurrence and magnitude of LH surges were greater (P<0.01) and intervals to onset of LH surge were longer (P<0.01) in P(4)-supplement-treated than control ewes. In Exp. 2, P(4) supplement elevated P(4) levels from 1.8+/-0.1ng/mL on Day -1 to 4.2+/-0.3 on Day 0 (P<0.001). Following pessaries removal, P(4) concentrations fell to basal values on Day 1 in both groups and remained low until Day 5. Then, P(4) concentrations increased and remained elevated through Day 19 in all (100%) progestagen-supplement-treated in Exp. 1 (12/12) and Exp. 2 (14/14) and in only 5/12 (41.7%) and 6/14 (42.9%) control ewes, respectively. These ewes were confirmed pregnant by ultrasonography and lambed on Day 149.2+/-0.2 following Day 0. In conclusion, progestagen supplement 24h prior to removal of pessary can be used successfully to improve reproductive performance of ewes bred out-of-season.

The effect of progesterone and oestradiol benzoate on fertility of artificially inseminated repeat-breeder dairy cows during summer.

An experiment was conducted to examine the effect of progesterone (P(4)) and oestradiol benzoate (ODB) on fertility of repeat-breeder lactating dairy cows during summer. One hundred repeat-breeder lactating dairy cows were randomly allocated to four groups (Tr1, Tr2, Tr3 and C) in a study conducted at a private dairy farm. All cows were injected with 2 mg ODB (day 0), which were at random stages of their oestrous cycles. Cows in Tr1, Tr2 and Tr3 were administered with intravaginal progesterone-releasing devices (controlled internal drug-releasing, CIDR) at the time of ODB injection for 7 days and those in group C were untreated and served as controls. Following CIDR removal, all cows were given an intramuscular injection of 25 mg Prostaglandin (PGF(2 alpha)). Twenty-four hours after the PGF(2 alpha) injection, cows in Tr1, Tr2 and C groups were injected with 1 mg ODB. Cows in Tr3 group were injected with 10 microg gonadotropin-releasing hormone (GnRH) agonist 48 h after CIDR removal. Artificial insemination was performed between 24 and 30 h following the second ODB injection for cows in Tr1 group and at the time of GnRH injection for cows in Tr3 group. Cows in Tr2 and C groups were inseminated at detected oestrus. Plasma P(4) and oestradiol 17beta (E(2)) concentrations were determined for all cows daily from day 0 to day 9. Plasma concentrations of P(4) and E(2) among cows of groups Tr1, Tr2 and Tr3 were increased and reached maximum values within 48 h following administration and were greater (p < 0.001) than those of group C cows. The proportion of cows detected in oestrus based on P4 concentration on day 9 was 88%, 72%, 88% and 60% in groups Tr1, Tr2, Tr3 and C, respectively. Oestrous detection rate differed (p < 0.01) significantly between time-inseminated groups (Tr1 and Tr3) and those inseminated at observed oestrous (Tr2 and C) groups. Pregnancy rates based on ultrasonography performed on day 28 were 52%, 56%, 60% and 40%, and those based on rectal palpation on day 45 were 32%, 44%, 36% and 28% for Tr1, Tr2, Tr3 and C cows (p > 0.1), respectively. Whereas pregnancy rates for cows with four or more previous services in all groups (54.55%) were higher (p < 0.03) than those for cows with three previous services (29.49%). In pregnant cows, mean days from calving to the day of insemination were higher (p < 0.01) among cows with four or more previous services (204 +/- 8.0 days) than those with three previous services (157 +/- 6.0 days). Results indicate that treatment with a combination of ODB and CIDR in repeat-breeder dairy cows causes elevation in plasma concentrations of E(2) and P(4). Oestrous detection rate was better in cows that were primed with P(4) than those without P(4) priming. Cows with four or more previous services had significantly higher pregnancy rates than those with three previous services.

A new approach to enhance reproductive performance in sheep using royal jelly in comparison with equine chorionic gonadotropin.

The objective was to compare the effects of royal jelly (RJ) and eCG treatments on reproductive performance of ewes synchronized using intravaginal progesterone-releasing devices. Forty-two cycling Awassi ewes were treated intramuscularly (i.m.) with 15 mg PGF2alpha. On the following day, all ewes were administered with CIDR-G for 12 days and were randomly allocated to three (RJ, eCG and control) groups of 14 ewes each. Ewes in the RJ-treated group received daily i.m. treatments of 400mg RJ during the period of CIDR-treatment. Each ewe in the eCG-treated group received an i.m. treatment of 500 IU eCG at the time of CIDR-G removal (day 0) and no further treatment was given to ewes in the control group. Ewes were exposed to four fertile rams for 72 h, from the time of CIDR-G removal, and checked for breeding marks at 6-h intervals. Blood samples were collected from day -13 until day 0 and thereafter until day 19 for progesterone analysis. Royal jelly treatment resulted in a greater rate of decline and lower (P<0.02) progesterone concentrations between days -10 and 0 than eCG-treated and control ewes. Expression of estrus was similar among the three groups and intervals to onset of estrus were shorter (P<0.01) in RJ-treated (31.3h) and eCG-treated (29.8h) than control (41.3h) ewes. First-cycle pregnancy and lambing rates were greater (P<0.05) in RJ-treated (71.4 and 71.4%) and eCG-treated (85.7 and 78.6%) than in control (42.9 and 35.7%) ewes, respectively. Results demonstrate that the treatments of RJ and eCG in conjunction with CIDR-G were similarly effective in induction of estrus and improvement of pregnancy and lambing rates.

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.

Nutritive value of lentil and vetch straws as compared with alfalfa hay and wheat straw for replacement ewe lambs.

The objective of this study was to compare the nutritive value of lentil straw (LS) and vetch straws (VS) with alfalfa hay (AH) and wheat straw (WS). Forty Awassi ewes (body weight (BW)=56.2kg) were assigned randomly to four dietary treatments (10 ewes per treatment) for 6 weeks using a complete randomize design. In each dietary treatment, ewes were fed 550g per day of concentrate mix formulated to supply 40% of the metabolizable energy requirement. After the consumption of the concentrate mix, ewes had ad libtum access to AH, LS, VS, or WS. Forage intake, total dry matter intake (DMI), and organic matter intake (OMI) were higher for AH and LS and lowest for WS. Final weight of ewes fed AH and LS diets were higher (P<0.05) than VS and WS diets. However, ewes fed VS diet gained more weight (2.5kg) than ewes on WS diet (0.2kg). Dry matter digestibility was higher for the AH and LS diets (59.4%), and lowest for WS diet (49.6%). The VS diet had an intermediate value (54.4%). Ruminal passage rate was higher for AH and LS (3.4% per hour) compared with WS (1.9% per hour). Eating time for the AH diet was lowest compared with the rest of the forages. Eating time, expressed as minutes per kilogram NDF intake, was highest for WS and VS diets (680min) compared with AH and LS diets (535min). WS diet required more time for rumination (395min per day) compared to AH, LS, and VS diets. However, ewes on VS diet spent more time ruminating per kilogram NDF consumed (954min) compared with WS, LS, and AH diets (901, 617, and 597min, respectively). These results were significant and demonstrate that the nutritive value of LS is greater than VS and close to the nutritive value of AH. VS nutritive value is slightly greater than WS.

Effect of eCG on the pregnancy rate of ewes transcervically inseminated with frozen-thawed semen outside the breeding season.

An experiment was conducted to determine whether factors affecting pregnancy rate out-of-season are associated more with transcervical artificial insemination (T-AI) procedures or with the reproductive state of the ewe. Twenty Finncross ewes were treated with progesterone sponges, and at sponge removal (0 h) 10 ewes were treated with eCG. Blood samples were collected for LH and progesterone analyses, and follicular development was monitored using ultrasonography. Ewes were inseminated from 48 to 52 h with 200 million motile frozen-thawed spermatozoa. The incidence of estrus, LH surges and ovulation was greater (P < 0.01) and intervals to these responses were shorter (P < 0.01) in the eCG-treated ewes. The number of follicles > 5 mm was higher (P < 0.05) in eCG-treated than control ewes. Progesterone concentrations increased and remained elevated through Day 19 in 7 eCG-treated and in 1 control ewe, and these ewes were pregnant based upon ultrasonographic examination. The results demonstrate that the T-AI technique using frozen-thawed semen produces a relatively high (70%) pregnancy rate out-of-season. The pregnancy rate was found to reflect primarily the reproductive condition of the ewe.