Estrus Synchronization Protocol Research Articles

Efficacy of Estrus Synchronization Protocols during Summer and Winter Seasons together with Biochemical and Minerals Profile in Anoestrus Crossbred Cows

The estrus induction and fertility response along with biochemical and minerals profile of >90 days postpartum anoestrus crossbred cows following use of different estrus synchronization protocols was investigated during summer and winter seasons. The true anoestrus cows selected (n=43 in summer, n=40 in winter) were randomly treated with Ovsynch, Heatsynch and PRID protocols keeping 10 animals as control in both the seasons. During summer season, the estrus induction response with Ovsynch, Heatsynch and PRID protocol was 80, 90 and 80 %; while in winter season, the response was 100% with all three protocols. In summer season, the conception rates with Ovsynch, Heatsynch and PRID protocols at induced estrus were 30, 20 and 20 %and those of 3 cycles 60, 40 and 50 %, respectively, while in winter season, the conception rates at induced estrus were 45.45, 27.27 and 36.36 % and overall of 3 cycles 72.72, 45.45 and 63.64%, respectively. The overall mean plasma concentrations of total cholesterol (mg/dl) in anoestrus cows under Ovsynch, Heatsynch and PRID protocols were 171.57±4.75, 190.97±4.90 and 184.93±3.10 during winter and 163.73±4.96, 162.87±11.24 and 177.63±7.98 during summer, respectively. The corresponding values for plasma total protein (g/dl) during winter season were 7.77±0.11, 7.90±0.12and7.51±0.14, and in summer season 7.90±0.14, 8.02±0.67 and 8.32±0.10, respectively. The cholesterol levels were insignificantly lower and protein levels were significantly higher in summer than winter season, particularly in non-conceived cows. Among the minerals profiles, i.e. calcium, phosphorus and magnesium, only the calcium levels were significantly higher during winter and in conceived cows as compared to counter parts. In conclusion, the results showed that estrus synchronization with fixed time insemination protocols can augment fertility in anoestrus crossbred cows under favorable as well as heat stress condition, and the response is better with Ovsynch and PRID protocols without influencing much the blood metabolic profil

158 Effects of an AI plastic sheath with three semen outputs on AI pregnancy rates of beef heifers enrolled in estrus synchronization protocols

158 Effects of an AI plastic sheath with three semen outputs on AI pregnancy rates of beef heifers enrolled in estrus synchronization protocols

497 Effects of post-weaning plane of nutrition and estrus synchronization on reproductive performance of Bos indicus-influenced beef heifers

A 3-year study evaluated the effectiveness of estrus synchronization of beef heifers undergoing different post-weaning growth rates. On day 0 of each yr, Angus × Brahman heifers (60 heifers/year; 310 days of age) were stratified by initial BW and age, and randomly assigned, in a 3 × 2 factorial design, to achieve a low (LOW; 0.45 kg/d), medium (MED; 0.73 kg/d), or high (HIG; 1.00 kg/d) growth rate from d 0 to 168 (5 heifers/pasture; 4 pastures/diet/yr). Supplements were formulated to allow LOW, MED, and HIG heifers to achieve 55.0, 62.5, and 70.0%, respectively, of mature weight at initiation of breeding season (d 84). On d 65, all heifers within each pasture (2 pastures/diet) were enrolled (SYNC) or not (NOSYNC) in an estrus-synchronization protocol, which consisted of intravaginal controlled internal drug release (1.38 g P4) insertion on d 65 and removal on d 75, followed by 100-µg i.m. injection of GnRH on d 77, and 25-mg i.m. injection of PGF2α on d 84. Heifers were stratified by diet (1 pasture/diet) and exposed to Angus × Brahman bulls from d 84 to 168 (1 yearling bull/pasture). Pasture was the experimental unit, whereas year, heifer (pasture), and pasture (diet × synchronization) were included as random effects in all analyses. Growth performance, and puberty and calving distribution were analyzed using MIXED and GLIMMIX procedures of SAS, respectively. Interactions among growth rate, estrus synchronization, and time were not detected for any variable (P ≥ 0.26). Overall heifer ADG achieved only 51 to 56% of targeted ADG, and mature BW on d 84 did not differ between MED and HIG heifers (57.6 vs. 58.6 ± 2.40%; P = 0.30), but both were heavier than LOW heifers (53.7 ± 2.40%; P < 0.0001). Percentage of pubertal heifers on day 84 was greater for MED and HIG vs. LOW heifers (44.4 and 45.4 vs. 26.5 ± 6.77% P ≤ 0.05), whereas estrus synchronization increased attainment of puberty on d 84 (23.5 vs. 48.7 ± 4.64% for NOSYNC and SYNC heifers; P < 0.01). Pregnancy and calving rates were not affected by diet or estrus synchronization (P ≥ 0.24), however heifers calved 9 d earlier with the use of estrus synchronization (P = 0.02). Estrus synchronization resulted in earlier attainment of puberty and pregnancy in Bos indicus-influenced beef heifers; however, at the low rates of BW gain achieved in the current study, estrus synchronization did not impact overall reproductive success.

118 Is the time of insemination linked with the reproductive response of the animal? Assessment of follicular size at fixed-time artificial insemination and behavioral patterns in beef cattle following seven-day CO-Synch + controlled internal drug release estrus synchronization protocol

118 Is the time of insemination linked with the reproductive response of the animal? Assessment of follicular size at fixed-time artificial insemination and behavioral patterns in beef cattle following seven-day CO-Synch + controlled internal drug release estrus synchronization protocol

448 The effects of a novel follicle wave and heat synchronization protocol on the follicles, circulating hormones, and estrus of Aanestrous ewes

Reproductive performance in seasonally anestrous ewes is poor even after the use of current controlled breeding protocols. Anestrous ewes treated with a medroxyprogesterone acetate sponge, for 12 or 14 d, and estradiol-17β (E2) have synchronized follicular wave emergence. The objective of this study was to determine the effects of an E2 injection 6 d after CIDR insertion on follicles, E2 and LH concentrations, and estrus in seasonally anestrous ewes. Ewes (n = 13) received CIDRs (Day -12) followed by an injection of eCG (500 IU; i.m.; Day 0) at CIDR removal and an injection of sesame oil without (1 mL; i.m.; Control) or with E2 (350µg; i.m.; Day -6) 6 d before CIDR removal. Treatments were balanced for age, parity, and BCS. Blood samples were collected every 6 h for 48 h after E2 injection and every 3 h for 60 h starting 18 h after eCG injection to determine LH concentrations. Blood samples were collected on Day -6 and 0 and every 6 h for 60 h starting 18 h after eCG injection to determine E2 concentrations. Ovarian ultrasonography was done on Day -6 and 0. A ram was introduced on Day 1 to observe estrus. Ewes treated with E2 had higher LH concentrations (0.37 ± 0.05 ng/mL) than ewes treated with oil alone (0.12±0.05 ng/mL) during the 48 h after E2 injection (P < 0.005). Concentrations of LH were highest at 18 h after E2 injection (1.11 ± 0.12 ng/mL; P < 0.001). Ewes treated with E2 had higher LH concentrations (2.10 ± 0.18 ng/mL) than ewes treated with oil alone (0.12 ± 0.16 ng/mL) at 18 h after E2 injection (P < 0.001). The interval from eCG injection to the start of the pre-ovulatory LH surge was similar (37.1 ± 4.4 h; P > 0.05), but was more synchronized in ewes treated with E2 (2.3 ± 0.6 h) than ewes treated with oil alone (12.0 ± 5.1 h; P < 0.01). Concentrations of E2 were similar between treatments on Day -6 (2.1 ± 0.3 pg/mL; P > 0.05) and Day 0 (2.3 ± 0.4 pg/mL; P > 0.05). Concentrations of E2 tended to be highest at 18 h after eCG injection (3.5 ± 0.5 pg/mL; P = 0.076). Maximum follicular diameter was larger on Day 0 (4.8 ± 0.2 mm) than Day -6 (3.4 ± 0.2 mm; P < 0.001). There were no differences in the interval from eCG treatment to the start (37.6 ± 2.7 h) or end (74.7 ± 1.9 h) of estrus (P > 0.05). Adding an E2 treatment during a CIDR-eCG estrus synchronization protocol increased LH concentrations after E2 treatment and stimulated a more synchronized pre-ovulatory LH surge in seasonally anestrous ewes.

477 Effects of delayed insemination on pregnancy rates of suckled beef cows enrolled in the 7-d CO-Synch+Cidr estrus synchronization protocol and that were not detected in estrus by the time of fixed-time AI

477 Effects of delayed insemination on pregnancy rates of suckled beef cows enrolled in the 7-d CO-Synch+Cidr estrus synchronization protocol and that were not detected in estrus by the time of fixed-time AI

Effect of PRID-Delta devices associated with shortened estrus synchronization protocols on estrous response and fertility in dairy cows

Abstract This study evaluated the effect of a once-used progesterone (P4) intravaginal device (PRID) associated with four different shortened P4-based estrus synchronization (ES) protocols on estrous response (ER) and pregnancy per AI (P/AI) in cyclic and acyclic lactating dairy cows. Cows (n=465) were randomly assigned to one of the following protocols: 1) 2PGG, cows were given a PRID-Delta and 100 μg GnRH i.m. at PRID insertion (day 0). The PRID was left for 5 d, and 25 mg of dinoprost (PGF2α) i.m. given twice at PRID removal and 24 h later; 2) 2PGGe, same treatments as 2PGG plus 500 IU of eCG i.m. at PRID removal; 3) 2PGe, same treatments as 2PGGe, except GnRH was not given at PRID insertion; 4) PGe, same treatments as 2PGe, except PGF was only given at PRID removal. A total of 258 cows received a new PRID-Delta containing 1.55 g of P4, whereas 207 cows received a once-used PRID. Estrus was determined from P4 device removal until 96 h after using an automated heat detection system. Cows in estrus were given a second GnRH at AI and those without signs of estrus by 96 h after PRID removal were given GnRH and timed-AI (TA I). All inseminations were performed by one technician with commercially available frozen-thawed semen. Ultrasonography was performed at initiation of protocol and 28-34 days post AI to determine cyclicity and pregnancy status, respectively. Cows receiving once-used P4 devices had greater ER than cows receiving a new device (59.9 vs. 50.0; P=0.029), but P/AI did not differ between P4 devices, respectively (P&gt;0.1; 40.6 vs 40.7%). Cyclic cows were less likely to display estrus than acyclic cows by a factor of 0.66 (P=0.036). Cows subjected to the 2PGe (2.41; P&lt;0.01) protocol were more likely to display estrus than cows subjected to the 2PGG, whereas cows subjected to the PGe protocol did not differ (0.94; P=0.8) from those in the 2PGG group. Despite differences in ER, neither cyclicity nor estrus synchronization protocol affected P/AI (overall 40.6%). In summary, cyclic cows, those given a new P4 device and those subjected to either 2PGG or PGe protocol had reduced ER. However, all the factors examined had no significant effect on P/AI. All the estrus synchronization protocols resulted in acceptable fertility.

Optimization of Estrus Synchronization Protocol for Target Breeding to

Optimization of Estrus Synchronization Protocol for Target Breeding to

Maternal and non-maternal factors associated with late embryonic and early fetal losses in dairy cows

Defining factors associated with embryonic and/or fetal losses will be helpful in overcoming such problem, either by adjusting conditions or applying therapeutic approaches to high-risk cows. The objective of this study was to investigate the association between a number of maternal and non-maternal factors and the risk of late embryonic (LED) and early fetal death (EFD) in dairy herds. Additionally, we investigated the effect of treating pregnant cows either with GnRH on day 26 post-insemination, or GnRH on day 26 plus CIDR insertion between days 26 and 33 post-insemination, on the risk of LED/EFD. From 3826 pregnancies, diagnosed at day 30 post-insemination, 851 cows lost the pregnancy by day 70 post-insemination. A mixed-effects logistic model was constructed to assess the effect of cow breed, calving difficulty, postpartum problems, lactation number, days in milk, insemination number, actual 305-day milk production, temperature humidity index (THI) at insemination, estrus synchronization protocols, and other factors, on the risk of LED/EFD. Our findings indicated that Holstein X Brown Swiss crossbreed cows had a lower risk for LED/EFD than Holstein cows (P < 0.05). Cows that had postpartum problems, were inseminated for the first time, produced more milk, or were inseminated at THI ≥75, recorded higher risks of LED/EFD (P < 0.05). Calving difficulty, lactation number, and synchronization protocols were not found to be associated with LED/EFD. Moreover, treatment of the pregnant cows with GnRH on day 26 post-insemination plus CIDR insertion between days 26 and 33 post-insemination decreased the risk of LED/EFD. In conclusion, cows that had postpartum problems, were inseminated early postpartum, produced higher milk, and/or were inseminated at high THI, were under higher risk of LED/EFD. Treating such cows with GnRH on day 26 plus CIDR insertion between days 26 and 33 may decrease the possibility of the LED/EFD.

Evaluation of the 14-d CIDR-PG and 9-d CIDR-PG protocols for synchronization of estrus in Bos indicus-influenced and Bos taurus beef heifers

Two long-term, CIDR-based estrus synchronization protocols were evaluated among Bos indicus-influenced and Bos taurus beef heifers. Treatments were evaluated on the basis of estrous response and pregnancy rate resulting from fixed-time artificial insemination (FTAI), and these outcomes were analyzed retrospectively relative to reproductive tract score (RTS; Scale 1–5) at treatment initiation. Estrus was synchronized for 1139 heifers in three locations, and heifers were assigned to one of two treatments within each location based on RTS. Heifers assigned to the 14-d CIDR-PG protocol received a controlled internal drug release (CIDR) insert (1.38 g progesterone) on Day 0, CIDR removal on Day 14, administration of prostaglandin F2α (PG; 25 mg im) on Day 30, and administration of gonadotropin-releasing hormone (GnRH; 100 μg im) concurrent with FTAI on Day 33, 66 h after PG. Heifers assigned to the 9-d CIDR-PG protocol received administration of PG concurrent with CIDR insertion on Day 5, administration of PG concurrent with CIDR removal on Day 14, administration of PG on Day 30, and administration of GnRH concurrent with FTAI on Day 33, 66 h after PG. Estrus detection aids were applied at CIDR removal on Day 14 and at PG on Day 30 to evaluate estrous response rate. Mean RTS differed (P < 0.0001) based on biological type due to higher rates of estrous cyclicity (RTS 4 and 5) among Bos taurus heifers (72%; 416/574) than among Bos indicus-influenced heifers (27%; 150/565). The proportion of heifers expressing estrus following CIDR removal was greater (P = 0.01) among heifers assigned to the 14-d CIDR-PG treatment (88%; 492/559) compared to the 9-d CIDR-PG treatment (83%; 480/580). Estrous response following CIDR removal was also higher (P < 0.0001) among Bos taurus (95%; 547/574) compared to Bos indicus-influenced (75%; 425/565) heifers. Rate of estrous response prior to FTAI did not differ significantly based on treatment but was higher (P < 0.0001) among Bos taurus heifers (60%; 344/574) than among Bos indicus-influenced heifers (45%; 253/565). However, the effect of biological type on estrous response was not significant when RTS was included in the model, as RTS significantly (P < 0.0001) affected the rate of estrous response both at CIDR removal and prior to FTAI. Across treatments and biological types, heifers that expressed estrus prior to AI achieved higher (P < 0.0001) AI pregnancy rates than heifers failing to express estrus. Pregnancy rates to FTAI did not differ significantly based on treatment in either biological type. Higher rates of estrous cyclicity among Bos taurus heifers resulted in higher FTAI pregnancy rates among Bos taurus (51%; 290/574) compared to Bos indicus-influenced heifers (39%; 218/565). However, pregnancy rates of respective RTS did not differ based on biological type. In summary, long-term CIDR-based protocols provide a simple, effective method of estrus synchronization in Bos indicus-influenced and Bos taurus beef heifers. Moreover, these results highlight the importance of management practices that result in high rates of estrous cyclicity prior to protocol initiation, particularly among later maturing breeds and biological types.

Effect of barium selenate injections on fertility of Pirlak ewes subjected to estrus synchronization during non-breeding season

This study was aimed at determining the effect of barium selenate injections on the fertility of Pirlak ewes which had been subjected to progesterone-assisted estrus synchronization during the non-breeding season. A total of 150 Pirlak ewes between the ages of 2 and 5 years were used in the study. Sponges containing progesterone were inserted into the vaginas of the ewes for 11 (groups I and III) or 14 days (groups II and IV) for the purpose of estrus synchronization, and 500 IU equine chorionic gonadotropin (eCG) was administered on the day of sponge removal. In addition, barium selenate was injected s.c. immediately before estrus synchronization protocol in groups I and III. After the sponges had been removed, estrus was observed for four days. The ewes were mated with fertile rams. The pregnancy was determined by transrectal ultrasonography 30 days after mating. It was observed that the estrus rate, pregnancy rate, conception rate, lambing rate, twinning rate, and litter size were not statistically different (P &gt; 0.05) between the groups, but estrus onset was different (P &lt; 0.001). In conclusion, barium selenate injections did not affect the fertility parameters before progesterone-assisted synchronization was applied to the Pirlak ewes during the non-breeding season

15 QUANTIFICATION OF BULL SPERM TRAITS AS ASSESSED BY COMPUTER-ASSISTED SEMEN ANALYSIS AND THE RELATIONSHIP TO PREGNANCY RATE FOLLOWING CONTROLLED BREEDING

The bull’s contribution through artificial insemination to reproductive efficiency is of great biological importance. The objectives were (1) to compare the oestrous synchronization response of Bonsmara and Nguni cows; and (2) to find the relationship between cow’s conception rate (in vivo and in vitro fertilization) and bull sperm motility rate assessed by computer-assisted semen analysis (CASA) following AI. For the in vivo sperm fertility test, 100 Bonsmara and 482 Nguni cows were randomly selected and subjected to oestrous synchronization protocol and AI with frozen–thawed assessed semen by CASA before AI. Briefly at Day 0, cows were inserted with an intravaginal CIDR® (1.9 g), which was removed on Day 7. Prostaglandin was then administered (2 mL) on Day 8 and a heatmount detector was placed on the hindquarter of each cow. For the in vitro sperm fertility test, collected oocytes from slaughterhouse were in vitro matured (n = 360) and in vitro fertilized (sperm/mL) in 100-µL droplets (final volume) of BO-IVF medium per treatment bulls (Bonsmara or Nguni bull). The frozen/thawed semen straws of Bonsmara and Nguni bulls were randomly selected and used under the same IVF conditions. The thawed bull’s sperm characteristics were examined by CASA before in vitro fertilization. Data were analysed using ANOVA. Treatment means were compared using the Fisher’s protected least significant difference t-test. There was no significant difference in oestrous response for the Bonsmara (83.0%) and Nguni (90.8%) cows, respectively. The Bonsmara cows recorded a significantly higher pregnancy rate (59.0%) compared with the Nguni (37.1%) cows (P &lt; 0.05). Sperm traits such as total motility (TM), progressive motility and rapid were found to be positively correlated with conception rate (r = 0.06, 0.03, and 0.08, respectively; P &lt; 0.01), although correlations were low. There was no difference in the average frozen–thawed sperm TM rate of Nguni (92.2%) and Bonsmara (81.0%). There was a lower fertilization rate following IVF with Bonsmara and Nguni bull sperm. In conclusion, Nguni cows had similar oestrous response as Bonsmara cows. The sperm traits from Bonsmara and Nguni bulls were found to be related to in vivo conception and in vitro fertilization rate when sperm cells were assessed by CASA technology. However, the pregnancy rate was lower in Nguni cows.

Appraisal of Different Protocols for Estrus Synchronization in Local Rahmani Sheep

Appraisal of Different Protocols for Estrus Synchronization in Local Rahmani Sheep

Risk Factors Influencing Conception Rate in Holstein Heifers before Artificial Insemination or Embryo Transfer

The objective of this study was to show the risk factors affecting the conception rate in Holstein heifers after synchronization of estrus. A total of 275 Holstein heifers housed in a free barn were used for the experiment. The herd was visited regularly at four week intervals for synchronization of estrus using Heatsynch and CIDR-Heatsynch protocols. A group of four to 14 animals, depending on the availability, were referred to the experiment at each visit. Estrus induction rates in the two protocols were 93.9% and 94.9%, respectively. There was no difference in the conception rate between the two protocols. Conception rate after artificial insemination (AI) or embryo transfer (ET) were 46.3% and 51.4%, respectively. The risk factors affecting conception rate in heifers were daily weight gain (odds ratio [OR]= 4.673; P= 0.036) and body condition score (BCS) (OR= 3.642; P= 0.018). Furthermore, estrus synchronization protocol (OR= 1.774; P= 0.083) and the absence of corpus luteum (CL) at the initiation of treatment (OR= 0.512; P= 0.061) had a tendency to affect the conception rate, while age (OR= 0.715; P= 0.008) was a protective factor to conception rate. In conclusion, positive daily weight gain before AI or ET, higher BCS, younger age, and the presence of CL at the initiation of estrus synchronization in dairy heifers increased the likelihood to conceive.

1115 The 9-d CIDR-PG protocol: Incorporation of prostaglandin pretreatment into a long-term, CIDR-based estrus synchronization protocol improves timed AI pregnancy rates in postpartum suckled beef cows

1115 The 9-d CIDR-PG protocol: Incorporation of prostaglandin pretreatment into a long-term, CIDR-based estrus synchronization protocol improves timed AI pregnancy rates in postpartum suckled beef cows

Técnicas de superovulação em ruminantes

The success of transfer programs embryos depends in large part to superovulate response, its limitation. In this regard, recent protocols, which control the follicular and luteal function, allow you to start the superovulatory treatment in a predetermined time. The superovulated objective supply the deficiency of the concentration of FSH before the dominant follicle promote the reduction of the concentration of this endogenous gonadotropin. There are numerous protocols for estrus synchronization and superovulation in ruminants, with the use of various drugs such as FSH, eCG, progestin, estrogen, PGF2a, GnRH agonists, etc.. They are also the various factors affecting the success of superovulation in ruminants among which is the early luteal regression, LH / FSH ratio, type of drug used, immunity, nutrition and body condition. This review aims to expose these protocols and the use of superovulatory drugs, as well as the effects of interfering factors.

Site of PGF2α injection does not alter effectiveness of the Select Synch + controlled internal drug release and timed artificial insemination protocol

Beef Quality Assurance programs have contributed to significant improvements in the wholesomeness of beef available for consumption. Injection site blemishes in the round have declined since the promotion of administering intramuscular injections in the neck. Unfortunately, many producers continue to administer estrus synchronization (ES) drugs in the rump. The objective of this study was to compare the effectiveness of injection site of PGF2α, in ES protocols, on steroid hormone concentrations and pregnancy rates. A Select Synch + 7-day controlled internal drug release ES protocol was conducted with the site of PGF2α injection alternated between neck and rump in beef cattle (n = 312) at the Ohio State University Agricultural Technical Institute and North Carolina State University. Blood samples (n = 75) were collected at controlled internal drug release insertion and at the time of artificial insemination (AI) to determine if progesterone (P4) and estrogen (E2) concentrations varied due to PGF2α injection site. All cattle were confirmed pregnant by ultrasonography at approximately 30 and 90 days after insemination in North Carolina and approximately 70 days after insemination in Ohio. Data were analyzed as randomized complete block designs in PROC GLIMMIX with animal as the experimental unit. Differences were declared significant at P < 0.05. Site of PGF2α injection, in either the neck or rump, did not affect (P > 0.05) overall conception rates in response to AI (58.4% and 55.6%, respectively). Altering PGF2α injection site did not impact P4, E2 concentrations, or the P4:E2 ratio at AI (P > 0.05). However, cattle inseminated after displaying estrus had greater (P < 0.05) pregnancy rates than timed AI (67.8 vs. 47.5%, respectively). First service conception rates and pregnancy rates were consistent with previous reports. Overall, altering the location of the PGF2α injection during ES did not change circulating hormone concentrations at AI or pregnancy rates; therefore, cattle producers should follow Beef Quality Assurance guidelines when administering ES protocols.

Consequences of eight consecutive applications of equine chorionic gonadotropin on ovarian follicle development and ovulation in bos indicus cows

ABSTRACT: The equine chorionic gonadotropin (eCG) is a glycoprotein produced in mare endometrial calices. In bovine, it is used in estrus synchronization protocols. However, studies have shown that it is potentially immunogenic and its effect can decrease after repetitive use. This study aimed to evaluate antral follicle dynamics, corpus luteum (CL) and ovulation rate in bos indicus cows submitted to an estrus synchronization protocol in association with eCG for eight times consecutively. Ten cyclical, multiparous, and pasture raised beef cows were divided into two groups: control group (n=5) and eCG group (n=5). In 30 day interval, all animals were synchronized with the same estrogen/progesterone based protocol, totalizing 8 re-synchronizations. Cows in the treatment group received 300IU eCG 48 hours prior to the presumable ovulation. Ultrassound examinations were performed on Day 4 of the protocol (approximately 1.5 days after follicle recruitment) to count antral follicles, on Day 10, to count antral follicles and to measure size of the largest follicle and on Day 18 to measure the diameter of the CL. No difference (P&gt;0.05) between follicular growth and size of the pre-ovulatory follicle was reported between groups. Cows treated with eCG had a larger (P&lt;0.05) CL and increased (P&lt;0.05) ovulation rate (18mm and 92%, respectively) when compared with control group (14.1mm and 80%, respectively). Furthermore, consecutive treatments did not affect CL nor ovulation rates. In conclusion, eCG treatment increased CL size and ovulation rate even after 8 consecutive treatments.

Modern Reproductive Technologies to Improve Cattle Production

Cattle contribute significantly to the global supply of animal-derived proteins which are an important part of a well-balanced human diet. With the human population increasing by 1 billion people every 13 years, there will be an estimated 9.6 billion people on planet Earth by the year 2050. To attain global food security the amount of available food will need to double between now and then. Enhancing reproductive efficiency is a prerequisite for boosting production of meat and milk from cattle, and, fortunately, an arsenal of modern reproductive technologies is available to assist with that effort. The objective of this manuscript is to provide an overview of reproductive biotechnologies that can bolster the efficient production of meat and milk from cattle. Protocols for synchronization of estrus and synchronization of ovulation facilitate more efficient artificial insemination using conventional or sex-sorted semen. In vivo and in vitro production of preimplantation embryos from genetically superior females enable creation of multiple offspring with high production potential. Biochemical and ultrasonographic methods for pregnancy testing identify non-pregnant females that can be re-mated or sold to prevent wastage of valuable feed resources. Somatic cell nuclear transfer is used to create copies of highly productive animals, and genome editing of zygotes provides a novel opportunity to selectively enhance the genetic makeup of cattle for the benefit of animal and human health. Wise use of these reproductive technologies will increase food production from cattle and will help alleviate world hunger.

The efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes

The aim of this study was to evaluate the efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes. A total of 158 crossbred buffaloes divided into four groups and were intramuscularly injected with 1×1010 (T1, n=41), 1×109 (T2, n=37), 1×108 (T3, n=37) or 0 (C, n=43) CFU/ml bacteria delivered inhibin vaccine in 10ml PBS on day 0 and 14, respectively. All animals were administered with 1000 IU PMSG on day 28, 0.5mg PGF2α on day 30 and 200μg GnRH on day 32. The results showed buffaloes immunized with the bacteria delivered inhibin vaccine had significantly higher titers of anti-inhibin IgG antibody than control group (P<0.01). The number and diameter of large follicles (≥10mm) as well as ovulatory follicles in group T1 was significantly greater than group C (P<0.05). The growth speed of dominant follicles in group T1 was significantly faster than groups T3 and C (P<0.05), resulting in a greater conception rate in buffaloes with positive antibodies. These results demonstrate that immunization with the bacterial delivered inhibin vaccine, coupled with the estrus synchronization protocol, could be used as an alternative approach to improve fertility in crossbred buffaloes.