Fixed-time Artificial Insemination Protocol Research Articles

180 Differences in Gene Expression in Granulosa Cells Harvested from Fertile and Sub-Fertile Beef Heifers

Abstract Infertility in beef replacement heifers is one of the leading contributors to economic losses in the cow-calf sector of the beef production industry. Successful reproduction is complex, involving multiple tissues and biological systems. This complexity makes identifying the leading causes of subfertility difficult. One potential source of fertility issues is poor oocyte health. As developing oocytes are dependent on granulosa cells (GCs) and physically coupled with GCs, we hypothesized that the gene expression profile would be different between the GCs from fertile heifers and those from sub-fertile heifers. The objective of this study was to identify differences in gene expression in GCs collected from beef heifers of differing fertility status, either fertile or sub-fertile. To gather this information, Angus-Simmental crossbred heifers underwent an estrus synchronization and fixed-time artificial insemination (AI) protocol (7-Day CO-synch + CIDR). At 41 days post-AI, heifers were pregnancy checked through ultrasound and palpation. Heifers pregnant to AI were classified as fertile (n = 8). Any heifers that remained non-pregnant following AI were exposed to bulls of proven fertility for 61 days. Bull-exposed heifers were evaluated for pregnancy 34 days after the bulls were removed. The non-pregnant heifers following both AI and natural service were classified as sub-fertile (n = 5). Pregnancies were terminated in fertile heifers, and heifers from both groups were allowed to resume normal cyclicity before GCs being harvested. RNA was extracted from GCs and quality was checked for each sample. Total RNA from GCs of 13 heifers was subjected to the library preparation and sequencing on the Nova-Seq platform. Through the application of DESeq2, 79 genes were identified as significantly differentially expressed genes (DEGs) with P-value < 0.05 and absolute (log2 fold change) > 0.5 including DNER, HOXD10, CD52, CXCL12, and HOXD11. DEGs, along with co-expressed genes, were over-represented in pathways associated with the regulation of MAP kinase activity, regulation of serine/threonine kinase activity, MHC protein binding, and plasma membrane signaling receptor complex. Through the pursuit of knowledge regarding the function of top DEGs, increased sample size, and more diverse sample collection time points, we may improve our understanding of the causation of heifer fertility issues. Improving our knowledge of heifer infertility has the potential to develop therapeutic options, and in turn, increase the efficiency and sustainability of cow-calf production systems.

Upgrading the fixed-time artificial insemination (FTAI) protocol in Romanian buffaloes.

The present study describes the challenges of assisted reproduction in Romanian buffaloes while increasing the efficacy of artificial insemination by choosing the most suitable method. The modified fixed-time artificial insemination (FTAI) protocol with sexed semen was used to increase the conception rate. This study included a total of 80 buffalo heifers that received ovarian stimulation using the OvSynch protocol. Two groups (n = 40), namely, a control group, in which the classic FTAI method was performed, and an experimental group, in which deep intrauterine AI was performed in cows that had developed a dominant follicle (US+UcFTAI), were randomly selected. The conception rate (CR) was 63.6% in the experimental group, which was statistically higher (P < 0.05) than the control group (30%). The ultrasound examination indicated that, using the OvSynch protocol, 82.5% (33 out of 40) of buffaloes developed a dominant follicle (DF) while the distribution between the warm and cold seasons was 75 and 90%, respectively. The CR was 60% during the hot season and 66.6% during the cold season. At calving, 92.5% female fetuses were born. The improved FTAI method in this study enhanced the results by reducing the waste of sexed semen and maximizing the response to OvSynch, making it a recommendation for practitioners. This study presents preliminary results and highlights that genetic progress is difficult to achieve. A systematic approach is needed in order to choose the most suitable biotechnological method for each farm.

Evaluation of two beef cow fixed-time AI protocols that utilize presynchronization

Presynchronization was evaluated as a method to improve estrus response before fixed-time AI (FTAI). The objective was to compare FTAI results in beef cows from two different presynchronization approaches. Blood samples were collected on Day −14 (Day 0 = CIDR removal) to determine progesterone concentration (≥1 ng/mL = high, <1 ng/mL = low). In a subset (n = 1289), an additional blood sample was collected between Day −21 and −29 to determine cyclicity (if both the Day −14 and Day −21 to −29 samples were classified as low progesterone cows were classified as noncycling). Cows (n = 1388) from 30 herds were grouped by days postpartum (DPP) and age, and randomly assigned to either of two protocols. Cows assigned to the PG 6-day CIDR & FTAI protocol (PG6d) received prostaglandin F2α (PG) on Day −9, CIDR insertion and GnRH on Day −6, and CIDR removal and PG on Day 0. Cows assigned to the 7&7 Synch protocol (7&7) were administered PG and CIDR insertion on Day −14, GnRH on Day −7, and CIDR removal and PG on Day 0. For both protocols, FTAI occurred concurrently with GnRH 66 h after second PG. Pregnancy was determined by transrectal ultrasonography 30–40 d after FTAI. The GLIMMIX procedure of SAS was used to detect differences in estrus response and pregnancy success with herd as a random variable. Estrus response (0–66 h) was analyzed with two models, one included cyclicity and another replaced cyclicity with progesterone concentration at Day −14. In both models, cows assigned to the 7&7 protocol had greater (P < 0.01) estrus response than cows assigned to the PG6d protocol. The model including cyclicity, estrus response was impacted by the cyclicity by DPP interaction (P = 0.03), cyclicity by protocol interaction (P = 0.04), and the tendency of BCS by protocol interaction (P = 0.08). In the estrus response model that included progesterone concentration at Day −14, significant variables included the protocol by progesterone concentration at Day −14 (P = 0.01), and BCS (P < 0.01), while DPP (P = 0.08) and progesterone concentration at Day −14 (P = 0.07) were tendencies. Pregnancy success was influenced by estrual status (P < 0.01), body condition score (P = 0.04), and cycling status (P = 0.02), but was not influenced by protocol (P = 0.75; PG6d = 38 ± 5% and 7&7 = 37 ± 5%). In conclusion, effectiveness of presynchronization method depended on a cows’ physiological status, and the 7&7 protocol increased estrus response compared with PG6d, but there was no difference in pregnancy success.

Environmental and behavioral effects on pregnancy rate of Nellore cows synchronized to fixed-time artificial insemination protocol: multivariate analysis

The aim of the study was to evaluate the influence of behavioral reactivity, body condition score (BCS), corral temperature (CT), difficulty and time of insemination on pregnancy rate of Nellore females raised in the Pantanal area and submitted to a fixed-time artificial insemination (FTAI) protocol. Thus, 167 females, kept in an extensive grazing system were evaluated. The variables recorded were BCS, escape velocity (EV), CT, insemination difficulty (ID), chute behavior (CB), insemination time (IT) and pregnancy rate. Initially, Fisher's Exact Test was performed to verify differences between expected and observed for BCS, CB, EV, ID, IT and CT, in which the influence of each variable on pregnancy rate was individually analyzed and it was not significant influence of these variables was observed (P&lt;0.05). Subsequently, the result of the pregnancy diagnosis (success = 1 and failure = 0) was used to study the probability of pregnancy. Multivariate analysis was used to assess the influence of several characteristics together on the conception rate, creating different evaluation scenarios. In none of the scenarios extracted from the cluster analysis was there a statistically relevant influence on the number of pregnancies. Under the conditions in which the study was conducted, there was no influence of corral temperature, reactivity, time and difficulty of insemination, body condition score and animal category on pregnancy rate of bovine females submitted to a FTAI protocol.

Comparison of Gonadotropin-Releasing Hormone versus Estrogen-Based Fixed-Time Artificial Insemination Protocols in Grazing Bos taurus Suckled Beef Cows.

Fixed-timed artificial insemination (FTAI) protocols for beef cattle in South America are primarily based on estradiol esters and intravaginal progesterone-releasing devices (IVPD). The objective of this study was to determine the optimal gonadotropin-releasing hormone (GnRH)-based protocol as an alternative to the use of estrogen-based protocols in grazing Bos taurus suckling beef cows. All cows received an IVPD on the day of protocol initiation and prostaglandin F2α (PG) plus equine chorionic gonadotropin (eCG) treatments at the time of IVPD removal. In Experiment 1, cows (n = 235) were randomly assigned to one of four treatments: (i) 7-day estradiol = 2 mg of estradiol benzoate (EB) at IVPD insertion on Day 9 and 1 mg of estradiol cypionate (ECP) at IVPD removal on Day 2; (ii) 7-day GnRH = 10 µg of GnRH at IVPD insertion on Day 10, IVPD removal on Day 3 and GnRH at FTAI; (iii) 7 & 7 estradiol = PG at IVPD insertion on Day 16, EB on Day 9 and ECP at IVPD removal on Day 2; (iv) 7 & 7 GnRH = PG at IVPD insertion on Day 17, GnRH on Day 10, IVPD removal on Day 3 and GnRH at FTAI. In Experiment 2, cows (n = 462) were randomly assigned to one of four treatments: (i) 6-day estradiol = EB at IVPD insertion on Day 9, IVPD removal on Day 3 and GnRH at FTAI; (ii) 7-day estradiol; (iii) 7-day GnRH; (iv) 7 & 7 GnRH. In Experiment 1, plasma progesterone concentrations and percentage of cows with a corpus luteum (CL) at IVPD removal, and pregnancy per AI (P/AI) were greater for cows subjected to GnRH-based protocols compared with cows subjected to estrogen-based protocols (p < 0.01). In Experiment 2, cows subjected to the 7 & 7 GnRH protocol had the greatest P/AI (p < 0.01). In summary, GnRH-based FTAI protocols resulted in similar or greater P/AI compared to estrogen-based FTAI protocols in grazing postpartum Bos taurus suckled beef cows. The greatest P/AI was attained with the 7 & 7 GnRH protocol.

Increased accuracy of estrus prediction using ruminoreticular biocapsule sensors in Hanwoo (Bos taurus coreanae) cows

Visual estrus observation can only be confirmed at a rate of 50%–60%, which is lower than that obtained using a biosensor. Thus, the use of biosensors provides more opportunities for artificial insemination because it is easier to confirm estrus than by visual observation. This study determines the accuracy of estrus prediction using a ruminoreticular biosensor by analyzing ruminoreticular temperature during the estrus cycle and measuring changes in body activity. One hundred and twenty-five Hanwoo cows (64 with a ruminal biosensor in the test group and 61 without biosensors in the control group) were studied. Ruminoreticular temperatures and body activities were measured every 10 min. The first service of artificial insemination used gonadotropin-releasing hormone (GnRH)-based fixed-time artificial insemination protocol in the control and test groups. The test group received artificial insemination based on the estrus prediction made by the biosensor, and the control group received artificial insemination according to visual estrus observation. Before artificial insemination, the ruminoreticular temperature was maintained at an average of 38.95 ± 0.05°C for 13 h (−21 to −9 h), 0.73°C higher than the average temperature observed at −48 h (38.22 ± 0.06°C). The body activity, measured using an indwelling 3-axis accelerometer, averaged 1502.57 ± 27.35 for approximately 21 h from −4 to −24 h before artificial insemination, showing 203 indexes higher body activity than −48 hours (1299 ± 9.72). Therefore, using an information and communication techonology (ICT)-based biosensor is highly effective because it can reduce the reproductive cost of a farm by accurately detecting estrus and increasing the rate of estrus confirmation in cattle.

Effect of melatonin implantation prior to ovsynch plus cidr protocol on subsequent ovarian activity and pregnancy rate in summer anestrous Murrah buffaloes

For assessing the impact of melatonin pre-treatment in summer anestrous Murrah buffaloes on subsequent reproductive activity of a fixed time artificial insemination (FTAI) protocol, 83 anestrous Murrah buffaloes were subcutaneously inserted 2x4 mm size absorbable melatonin (MT) implants (18 mg/50 kg b wt) at the base of left ear and 38 Murrah buffaloes were used as non-implanted controls. On day 35 post-MT, the treatment and control group Murrah buffaloes were subjected to FTAI protocol (Ovsynch plus CIDR). Ovarian ultrasonography and jugular vein blood sampling was carried out on day 7 and 10 of protocol and on day 7-post AI. Overall pregnancy rate on day 90 post-AI in MT group was higher compared to control group (55.4 vs 31.6%, P&lt;0.05), along with the higher (P&gt;0.05) plasma progesterone on day 7 of FTAI protocol in Murrah buffaloes of the former group which conceived subsequently compared to their non-pregnant counterparts. Moreover, MT group had higher (P&gt;0.05) increase in dominant follicle diameter between day 7 and 10 of protocol compared to control group. On day 7 post-AI, the luteal profile in pregnant murrah buffaloes of MT group was better (P&lt;0.05) compared to their counterparts in control group (CL: 14.80±0.70 vs 10.82±0.46 mm, P4: 1.54±0.07 vs 1.04±0.08 ng/ml). In conclusion, melatonin pre-treatment in summer anestrous Murrah buffaloes could be associated with better luteal activity and higher pregnancy rate in the Ovsynch+CIDR protocol.

Application of Exogenous GnRH in Food Animal Production.

Over several decades, exogenous GnRH and agonists have been employed for controlling reproductive cascades in animals, and treating some reproductive morbidities. The administration of GnRH is used in animals to counter ovarian dysfunction, induce ovulation, and to increase conception and pregnancy rates. GnRH and its agonists are used in the treatment of cystic ovarian degeneration and repeat breeder syndrome. The development of protocols for GnRH administration by intramuscular injection, intramuscular or subcutaneous implants, and intravaginal deposition has empowered their clinical use worldwide. Currently, exogenous GnRH products are a central part of several pre- and post-breeding programs for the enhancement of fertility, including the control of estrous cycles and timing of ovulation, development of fixed-time artificial insemination protocols, improved embryo survival, and the treatment of reproductive morbidity. The aim of the present review is to summarize the application of exogenous GnRH agonists in food animal production.

Supplementing Ca salts of soybean oil via low-moisture molasses-based blocks to improve reproductive performance and overall productivity of beef cows

This experiment evaluated reproductive and productive responses of beef cows receiving self-fed low-moisture blocks (LMB) enriched or not with Ca salts of soybean oil (CSSO) throughout the breeding season. Non-pregnant, suckled multiparous Angus-influenced cows were assigned to a fixed-time artificial insemination (AI) protocol (day −10 to 0) followed by natural service (day 15–70). Cows were managed in 12 groups (46 ± 4 cows/group) maintained in individual pastures, and groups received LMB enriched with 25 % (as-fed basis) of CSSO or ground corn (CON) from day − 10 to 100. Both treatments were designed to yield a daily LMB intake of 0.454 kg/cow (as-fed basis). Cows receiving CSSO had greater (P < 0.01) mean concentrations of ω-6 fatty acids in plasma samples collected on days 0 and 55. Cows receiving CSSO had greater (P = 0.05) pregnancy rate to fixed-time AI (67.2 vs. 59.3 %), whereas final pregnancy rate did not differ (P = 0.92) between treatments. Pregnancy loss was less (P = 0.03) in CSSO cows (4.50 vs. 9.04 %), which also calved earlier during the calving season (treatment × week; P = 0.04). Weaning rate tended to be greater (P = 0.09) in CSSO (84.8 vs. 79.4 %), although calf weaning age and weight did not differ (P ≥ 0.72) between treatments. Kilos of calf weaned/cow exposed was greater (P = 0.04) in CSSO cows (234 vs. 215 kg). Therefore, supplementing CSSO to beef cows via LMB during the breeding season improved their reproductive and overall productivity during a cow-calf cycle.

GnRH agonists: Updating fixed-time artificial insemination protocols in sows.

Protocols for fixed-time artificial insemination (FTAI) in swine reproduction can help increase genetic improvement and production efficiency. Different gonadotropin-releasing hormone (GnRH) agonists have been developed to gain better control of follicular development, timing, and ovulation quality; therefore, they have been extensively used in FTAI protocols. This literature review resumes the most important characteristics of the physiology of follicular development and ovulation in sows, followed by a discussion about the hormonal alternatives available to induce ovulation (human chorionic gonadotropin, hCG; porcine luteinizing hormone, LH and GnRH agonists). Also, ovulation induction failures with GnRH agonists are described. Finally, current FTAI protocols with GnRH agonists are resumed and discussed. FTAI with GnRH agonists has proven to be an efficient, successful reproductive protocol that can be implemented in pig farms due to better knowledge of an endocrine system that regulates follicular development and ovulation and increased availability of several GnRH agonists that allow more efficient reproductive swine programs.

Antral follicle count classification selects fertile heifers without influencing the carcass traits

This study aimed to evaluate the ovarian structure, estrus intensity, ultrasound carcass measurements, and pregnancy rate of Nelore breed heifers and cows in accordance with antral follicle counts (AFCs). We evaluated 503 heifers and 565 Nelore cows, with a mean age of 15.5±2.2 and 69.8±36.1 months, respectively, submitted to a fixed-time artificial insemination (FTAI) protocol. On day zero, all bovine females were examined using ultrasound to determine the AFC. The mean AFC of the heifers and cows were 20±8.6 and 22.5±8.4, respectively. The rib-eye area (REA) and fat thickness (FT) of the heifers (n = 119 for REA and n = 219 for FT) were measured using ultrasound imaging. The average conception rates at the first FTAI and at the end of the breeding season were 35.8% and 57.5%, respectively, for heifers and 45.1% and 78.9%, respectively, for cows. We demonstrated that the probability of pregnancy at the first FTAI and at the end of the breeding season for both young heifers and cows increased as the AFC decreased (P&gt;0.001 and P=0.0123, respectively). FT and REA showed no correlation with AFC in heifers. The intensity of estrus expression was negatively correlated with AFC (−0.46; P&lt;0.0001). In conclusion, Nelore heifers and cows with low AFC had a high probability of pregnancy during the entire breeding season. Thus, AFC can be used as a tool to select heifers with increased fertility without affecting carcass traits (REA and FT).

Response to hormonal treatment and conception rates of Sahiwal cows subjected to fixed time artificial insemination in pastoral dairy systems.

This study aimed at determining factors influencing response of Sahiwal cows/heifers to fixed time artificial insemination protocol in pastoral systems in Kenya. Available cows/heifers were inspected for conformity to Sahiwal breed characteristics, parity, body condition score, and subsequently rectal palpation to determine pregnancy status, ovarian structures, and estimated ovarian diameter. Consequently, these animals were injected with 100µg of gonadotrophin-releasing hormone. On days 7 and 9, only responsive cows/heifers were injected with 500µg of cloprostenol and 100µg of gonadorelin Acetate, respectively. On day 10, animals were inseminated and separated from bulls for 45days and pregnancy diagnosis done after 90days. Analysis of variance was performed to determine the effects of production system, parity, and ovarian structures on ovary diameters pre- and post-hormonal treatment. Logistic regression was used fitting a logit function to account for the binomial distribution of conception. Overall, 56.2%, 23.1%, and 20.7% of the animals had follicles (F), corpus luteum (CL), and corpus albicans (CA), respectively, at day 0, and 16.6%, 68.6%, and 14.8%, respectively, at day 7. Human and environmental factors had no influence on conception. Among the animal factors, only the ovarian structures at day 7 had a significant effect on conception. Ovaries with CL at this time were about 6 times significantly more likely to conceive than those with F. For higher conception rates, animals with ovaries with CL should be recruited into the FTAI program as they are significantly more likely to conceive than those with other ovarian structures.

Strategic re-use of intravaginal progesterone devices increases conception rate in primiparous Nellore cows

In the present study, we investigate the effect of the presence or absence of corpus luteum (CL) at the beginning of a fixed-time artificial insemination (FTAI) protocol and to evaluate the impact of one-time use of intravaginal progesterone device (P4 device) in cows with or without CL. A total of 776 primiparous Nellore cows were subjected to FTAI approximately 45 days postpartum. In Experiment 1, 476 cows were divided into two experimental groups: with (CL-present, n=113) or without (CL-absent, n=363) CL, after ultrasound evaluation. On day 0 (D0), all cows received a new P4 device (1.0 g) and 2.0 mg estradiol benzoate (EB). Eight days later (D8), the P4 devices were withdrawn, and prostaglandin (15 mg), estradiol cypionate (0.5 mg), and eCG (300 IU) were administered i.m. All cows were inseminated 48 h after P4 device withdrawal (D10). In Experiment 2, the cows (n= 300) received (at D0) P4 devices that were previously used once in other cows with (n=109) or without CL (n=191) and 2 mg of EB. The same protocol as that used in Experiment 1 was performed from D8 onwards. In Experiment 1, the overall conception rate after FTAI was 55% (262/476). No difference was found in the conception rate between CL-present and CL-absent cows (52.2 vs. 55.5%). In Experiment 2, the conception rate obtained with P4 devices previously used in cows with CL (58.7%) was greater (P&lt;0.05) than that obtained with P4 devices previously used in cows without CL (42.9%). Thus, this strategy resulted in a 15.8% increase in conception rate. In conclusion, the presence or absence of CL at the beginning of the FTAI protocol did not affect the conception rate in cows synchronized with the new P4 device, but the insertion of P4 devices previously used in cows with CL enhanced the conception rates in cows without CL.

Effect of Different Protocols of Fixed-Time Artificial Insemination on Mucus, Ovarian Size, and Pregnancy of Mixed-Breed Cows in the Humid Tropics of Peru.

The objective of the research was to evaluate three synchronization protocols for fixed-time artificial insemination (FTAI) in Bos indicus with Bos taurus crossbred cows. Forty-five cows of 5 ± 1.6 years were selected. The Jsynch treatment consisted of the application of an intravaginal device plus benzoate; on day 8, the device was removed and PGF2α, estradiol cypionate plus eCG was applied, and the FTAI was performed at 48-52 hours after. Conventional treatment consisted of the application of an intravaginal device plus benzoate; on day 8, the device was removed and PGF2α plus eCG was injected, and on day 9, estradiol benzoate was administered, and FTAI was performed at 30 hours. The Ovsynch treatment consisted of the application of GnRH, and on day 8, PGF2α was applied, on day 9, GnRH was applied again, and on day 10, FTAI plus GnRH was applied. The diagnosis of pregnancy was determined by transrectal ultrasound 45 days after the FTAI. The Jsynch (39.1%) and conventional (39.1%) treatment showed higher pregnancy compared to the Ovsynch treatment (21.7%) of pregnancy. The presence of crystalline mucus at the time of the FTAI was significantly associated with pregnancy. The results of this investigation indicate that it is possible to obtain acceptable pregnancy rates with the FTAI in B. indicus with B. taurus crossbred milk-producing cows, and treatments with progesterone-releasing devices plus eCG can improve the reproductive performance of cows.

Prohibition of hormones in animal reproduction: what to expect and what to do?

As our understanding of ovarian function in cattle has improved, our ability to control it has also increased. The development of Fixed-Time Artificial Insemination (FTAI) protocols at the end of the 20th century has increased exponentially the number of animals inseminated over the last 20 years. The main reasons for this growth were the possibility of obtaining acceptable pregnancy rates without heat detection and, above all, the induction of cyclicity in suckled cows in postpartum anestrus and prepubertal heifers at the beginning of the breeding season. Most FTAI treatments in South America have been based on the use of progesterone (P4) releasing devices and estradiol to synchronize both follicular wave emergence and ovulation, with pregnancy rates ranging from 40 to 60%. These protocols are implemented on a regular basis, allowing producers access to high-quality genetics, and increasing the overall pregnancy rates during the breeding season. In addition, it provided the professionals involved in these programs with a new source of income and the diversification of their practices into activities other than their usual clinical work. Many of these practices are now apparently at risk from restrictions on the use of estradiol by the European Union (EU) and other countries. However, the development of alternative protocols based on GnRH, with P4 devices and eCG and other new products that are not in the market yet will allow us to adapt to the new times that are coming. Logically, the challenge has already been raised and we must learn to use alternative protocols to try to continue increasing the use of this technology in beef and dairy herds. The objective of the present review is to describe the main aspects of banning estradiol in livestock production, the negative impacts on reproductive efficiency, and to present some alternative FTAI protocols for dairy and beef cattle.

Effects of supplementing narasin to Bos indicus heifers during late-gestation and lactation on development of the offspring.

This experiment evaluated the effects of supplementing narasin during late-gestation and lactation on productive and physiological responses of Bos indicus beef heifers and their offspring. Pregnant, nulliparous Nelore heifers (N = 88) that conceived under the same fixed-time artificial insemination protocol and to the same sire were used. Heifers were ranked by maternal ability genomic score, body weight (BW) and body condition score (BCS) and allocated to 44 drylot pens (2 heifers per pen; 10 × 25 m). Pens were ranked by these traits and alternatively assigned to receive (NAR) or not (CON) 0.260 mg of narasin/kg of heifer BW daily (Elanco Saúde Animal, São Paulo, Brazil). Narasin was mixed into a supplement offered at 0.30% of heifer BW from day 0 until heifers weaned their calves (day 316), whereas CON heifers received the same supplement without narasin addition. Heifers received Urochloa brizantha hay and water for ad libitum consumption (days 0 to 316) and calved between days 97 to 112 of the experiment. After calving, heifers and offspring had access to hay and supplement; hence, supplements and narasin were offered according to heifer + calf BW beginning on day 162. No treatment differences were detected (P ≥ 0.18) for heifer BW and BCS during the experiment, although BW loss from day 0 to calving was less (P = 0.04) in NAR compared to CON heifers. Hay intake during the experiment did not differ (P = 0.79) between treatments. Serum IGF-I concentrations were greater (P = 0.05) for NAR heifers on day 60 of the experiment and did not differ (P ≥ 0.28) between treatments 24 h and 30 d after calving (treatment × day interaction; P = 0.04). No treatment effects were detected (P ≥ 0.58) for calf birth BW. Serum concentrations of total protein 24 h after birth were greater (P = 0.04) in calves from NAR compared with CON heifers, and a tendency (P = 0.10) for a similar outcome was noted for serum IgG concentrations. Diarrhea incidence did not differ (P = 0.16) between treatments, although the number of total diarrhea cases per calf were greater (P = 0.03) in the CON offspring. Growth rate of calves from NAR heifers tended (P = 0.08) to be greater, resulting in heavier calves at weaning (P ≤ 0.04) compared with CON offspring. Collectively, these outcomes indicate narasin supplementation to beef heifers as a nutritional alternative to improve cow-calf productivity via developmental programming effects during gestation, as well as direct consumption by their nursing offspring.

Reproductive performance of fixed-time artificial insemination in heifers supplemented with a homeopathic complex

For this study, ½ blood nelore × aberdeen angus heifers (n = 40; 14 months) were divided into two groups: control (n=20; 310 kg) and pró-cio (n=20; 304 kg). for pró-cio group, 20g of homeopathic product (pró-cio®, real h, campo grande, brazil) was supplied together with corn eighteen days prior (d-18) to the beginning of the fixed-time artificial insemination protocol (ftai). on d0, all females received an intravaginal p4 device and 2 mg be. on d5, the afc was assessed by ultrasound and blood was collected for amh dosage. on d8, p4 device was removed; 300 iu ecg, 0.530 mg of cloprostenol sodium and 0.5 mg of ec were administered; an estrus-identifying adhesive was fixed at the tail insertion and the diameter of the dominant follicle (df) was measured. on d10, all heifers were inseminated, estrus manifestation was assessed and the preovulatory follicle (pof) was measured. on d20, the cl area was measured and blood flow was assessed using doppler ultrasound. data were analyzed by student, mann-whitney or friedman test. the rates of heat expression, ovulation, and blood flow score with doppler were analyzed using fisher’s exact test and pregnancy rate by binary logistic regression model (p ≤ 0.05). there was no difference in afc or amh dosage (p &gt; 0.05). pró-cio group had greater diameters of the df (9.94 ± 0.42 mm) and pof (11.61 ± 0.56 mm) than the controls (df: 7.72 ± 0.34 mm and pof: 9.91 ± 0.37 mm), as well a larger cl area (3.26 ± 0.26 versus 2.35 ± 0.16 cm2) and a higher mean cl vascularization score (3.06 versus 2.26; p &lt; 0.05). there was no significant difference (p &gt; 0.05) between estrus manifestation or conception rate for control and pró-cio groups. heifers supplemented with the homeopathic product showed larger follicular diameters at the end of the ftai protocol and cl with better blood flow scores compared to the control group.

185 Effect of time of equine chorionic gonadotrophin administration in a fixed-time artificial insemination protocol on ovulation, and corpus luteum area and blood flow of heifers

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

The proAKAP4 concentrations in Nelore bull sperm and their relation to FTAI conception rate results

The AKAP4 protein has an essential role in sperm motility, and its precursor, the proAKAP4, is considered a biomarker for sperm quality and fertility. Despite this, proAKAP4 concentration was never evaluated in Bos indicus sperm. Therefore, this study aims to determine the proAKAP4 concentration in the sperm of Nellore bulls and its association with sperm kinetics, morpho-functionality, morphology, and conception rates after fixed-time artificial insemination (FTAI). The bulls (n = 9) used in our study presented sperm characteristics above expected standards for quality. Sperm from each bull was evaluated regarding kinetics by the CASA system, and assessed for mitochondrial functionality, sperm membrane integrity, and morphology. For the FTAI protocol, multiparous Nelore cows (n = 1507) were inseminated with frozen-thawed sperm from the same batches used in the laboratory analysis. Additionally, the sperm proAKAP4 concentration was determined using an ELISA kit. The data were analyzed by linear regression and the significance level was set to 5%. The mean conception rate was 52.52%. The mean proAKAP4 concentration was 25.75 ng/106 spermatozoa. The proAKAP4 concentration positively affected the sperm total and progressive motilities, and conception rates after FTAI (respectively, r2 = 0.49, P = 0.03; r2 = 0.63, P = 0.01; and r2 = 0.51, P = 0.03). Based on the relationship detected in this study, we conclude that the sperm proAKAP4 concentration is a suitable biomarker to predict the quality and fertility of frozen-thawed Bos indicus semen.

Comparison of Estradiol Cypionate, Estradiol Benzoate and Gonadotropin-Releasing Hormone in Fixed-Time Artificial Insemination in Multiparous Murrah Buffaloes

The present study was aimed to evaluate the efficiency of estradiol cypionate, estradiol benzoate and gonadotropin-releasing hormone during fixed-time artificial insemination (FTAI) protocols in multiparous Murrah buffaloes. A total of 35 buffaloes were used between September and November 2021 and subjected to a synchronization protocol. On day 0, insertion of an intravaginal progesterone device (CIDR, 1.38 g) was made with intramuscular (i/m) injection of estradiol benzoate (EB, 2 mg); On day 9: CIDR removed with i/m injections of Dinoprost (12.5 mg) and eCG (400 IU), and then buffaloes were randomized into three treatment group: 1) EB 1 mg on day 10 (n=13). 2) estradiol cypionate (EC) 1 mg on day 9 (n=12), and 3) Buserelin acetate (GnRH) 0.0105 mg on day 10 (n=10). The estrus signs observed during the FTAI (56 h after CIDR withdrawal) and conception rate at 90 days after FTAI were recorded. The conception rates were 61.5, 58.3 and 60.0% for EB, EC and GnRH treatment groups, respectively. There was no significant difference between the treatment groups for conception rate and signs of estrus. Therefore, it was concluded that all three treatments can be efficiently used during estrus synchronization protocol with FTAI in multiparous Murrah buffaloes.