Expression Of Estrus Research Articles

Use of Injectable Progesterone as a Pre-Synchronisation Strategy in a Timed Artificial Insemination Protocol Based on Gonadotropin-Releasing Hormone and Progesterone in Bos indicus Beef Cows in Anoestrous.

This study evaluated the effects of pre-synchronisation with injectable progesterone (P4) on the ovarian follicular dynamics of Bos taurus indicus cows in anoestrous treated with a timed artificial insemination (TAI) protocol. Multiparous Nelore females (n = 47) at 30-60 days postpartum were used in this study. 10 days before (D-10) the TAI protocol, antral follicle count (AFC; follicles ≥ 3 mm), ovarian condition and body condition score (BCS; 1-5) were assessed and were randomly allocated into two groups: Pre-sync (n = 25), which underwent pre-synchronisation with 150 mg of injectableP4 intramuscularly (i.m.), and control (n = 22), which received the same volume of NaCL 0.9%. On D0, the ovarian assessment was repeated, and TAI protocol was initiated in all animals, with the insertion of an intravaginal P4 device and administration of 10.5 μg of buserelin acetate (gonadotropin-releasing hormone-GnRH). On D7, the P4 device was removed, and 300 IU of equine chorionic gonadotropin, 150 μg of D-cloprostenol and 1 mg of estradiol cypionate were administered i.m. On the same day (D7), the presence of the corpus luteum (CL) was assessed, the dominant follicle was measured, and the tail was painted to evaluate estrous expression. On D9, the largest follicle was remeasured, and TAI was performed. Animals that were not detected in oestrous at the time of AI were administered 10.5 μg of GnRH i.m. Numerical data were analysed using the Mann-Whitney U test. Binary data were analysed using the Fisher's exact test (5%). BCS, both at the beginning of pre-synchronisation (p = 0.45) and TAI protocol initiation (p = 0.20), and AFC (p = 0.36) did not differ between control and Pre-sync groups. The diameter of the largest follicle was similar between the control and Pre-sync groups on D-10 (p = 0.32), D0 (p = 0.33), D7 (p = 0.29) and D9 (p = 0.22). On D7 of the protocol, the Pre-sync group had a higher percentage of CL visible on transrectal ultrasonography (84.0%; p = 0.02) than the control group (54.5%); however, the expression during oestrous did not differ between groups (p = 0.59). The pregnancy rate was similar (p = 0.64) between groups and was not influenced by the CL rate on D7 (p = 0.48), oestrous expression (p = 0.20) or their interaction (p > 0.1). Pre-synchronisation effectively increased the proportion of cows with CL on D7 without altering the diameter of the largest follicle, oestrous expression or pregnancy rate in anoestrous cows treated with a GnRH/P4-based TAI protocol.

Predictive Models for the Implementation of Targeted Reproductive Management in Multiparous Cows on Automatic Milking Systems

Targeted reproductive management (TRM) aims to improve the fertility efficiency of the dairy herd by applying group-level management strategies based on expected reproductive performance. Key to the utility of TRM is the accuracy with which an animal's reproductive performance can be predicted. Automatic milking systems (AMS) allow for the collection of data relating to milk quantity, quality, and robot visit behavior throughout the transition period. In addition to this, auxiliary data sources such as rumination and activity monitors, as well as historical cow-level data are often readily available. The utility of this data for the prediction of fertility has not been previously explored. The objective of this study was first, to assess the accuracy with which the likelihood of expression of oestrus between 22 and 65 d in milk (DIM) and conception to first insemination between 22 and 80 DIM could be predicted using data collected by AMS from 1 to 21 DIM. Our second objective was to assess the change in model performance following the addition of 2 auxiliary data sources. Using data derived solely from the AMS (RBT data set) a binary random forest classification model was constructed for both outcomes of interest. The performance of these models was compared with models constructed using AMS data in conjunction with 2 auxiliary sources (RBT+ data set). Expression of oestrus was classified with an area under the receiver operator curve (AUC-ROC) of 0.6 and 0.65, conception to first insemination with an AUC-ROC of 0.56 and 0.62 for the RBT and RBT+ data sets respectively. No statistically significant improvement in classification accuracy was achieved by the addition of auxiliary data sources. This is the first study to report the utility of data collected by AMS for the prediction of reproductive performance. Though the performance described is comparable with previously reported models, their utility for the implementation of TRM is limited by poor classification accuracy within key sub-groups. Of note within this study is the failure of the addition of auxiliary data sources to increase the accuracy of prediction over models built using AMS data alone. We discuss the advantages and limitations the integration of additional data sources imposes on model training and deployment and suggest alternative methods to improve performance while preserving model parsimony.

Delaying induction of ovulation and timed AI in a Double-Ovsynch protocol increased expression of estrus and altered first service reproductive outcomes of lactating dairy cows

The objective of this randomized controlled experiment was to evaluate the effect of delaying induction of ovulation and timed artificial insemination (TAI) on expression of estrus before AI and first service reproductive outcomes. A secondary objective was to evaluate the effects of delaying induction of ovulation in a Double-Ovsynch protocol on ovarian function. Lactating Holstein cows (n = 4,672) from 2 commercial dairy farms fitted with sensors for automated detection of estrus were synchronized with a Double-Ovsynch protocol up to the first PGF2α (PGF-L) of the Breeding-Ovsynch portion of the protocol (Pre-Ovsynch: GnRH, 7 d later PGF2α, 3 d later GnRH, 7 d later Breeding-Ovsynch: GnRH, 7 d later PGF2α, 1 d later PGF2α). At PGF-L, cows blocked by parity (primiparous vs. multiparous) and semen used for first service (sex-sorted dairy vs. conventional beef) were randomly assigned to the G56 (n = 2,338) or G80 (n = 2,334) treatments. Cows in G56 had 56 h whereas cows in G80 had 80 h from PGF-L to induction of ovulation with the last GnRH (GnRH2) before AI. For both treatments, TAI occurred ∼16 h after GnRH2. All cows with automated estrus alerts between PGF-L and TAI were inseminated at detected estrus (AIE) without GnRH. Ovarian function and responses to synchronization were monitored based on circulating concentrations of progesterone and examination of the ovaries by ultrasonography. Data for binary outcomes were analyzed by logistic and continuous outcomes with lineal regression. More cows in G80 received AIE and had estrus before AI. Overall, pregnancies per AI (P/AI) did not differ for the G80 and G56 treatments. Cows in G80 that received TAI and had no estrus had fewer P/AI than cows with estrus that received AIE or TAI in G80, and fewer P/AI than cows AIE and cows that received TAI and had or did not have estrus in the G56 treatment. No differences were observed between treatments or for cows with and without estrus for pregnancy loss. Unlike some minor differences between treatments for concentrations of progesterone at GnRH2, the most notable differences in ovarian function were for cows in both treatments with or without estrus that received TAI. Cows with estrus, were more likely to have follicles > 16 mm, had larger follicles before ovulation, and had a greater ovulation risk after AI. Likewise, within the G80 treatment only, cows with estrus that received AIE or TAI had larger follicles, were more likely to have complete luteal regression, had greater ovulation risk, were more likely to have a functional corpus luteum, and had more circulating progesterone after AI. We concluded that delaying induction of ovulation and TAI was effective for allowing more cows to express estrus before AI which had different ovarian function outcomes and greater P/AI than cows that did not express estrus. However, the greater P/AI of cows that expressed estrus was insufficient to compensate for the reduced P/AI of cows that did not express estrus, and thus increase overall P/AI compared with the treatment without delayed induction of ovulation. Detection of estrus before AI in cows undergoing synchronization of ovulation could help identify cows with different likelihoods of pregnancy after insemination.

PSV-25 Investigating the effects of Chromium Propionate supplementation on productive and reproductive performance of beef cows

Abstract We investigated the effects of Chromium Propionate supplementation on reproductive performance of beef cows from pre-partum to weaning. Suckled beef cows at nine locations were enrolled in the study. Within location, cows were stratified by parity, dam age, and day postpartum (DPP) and randomly assigned to one of two treatments: 1) Control, supplementation of a mineral product at 113 gּ animal-1ּ d-1 (n = 464 cows; 13 experimental units); or 2) CrP, supplementation of mineral product at 113 gּ animal-1ּ d-1 containing 1.4 g of Chromium Propionate (0.4%KemTRACE Chromium 0.4%, Kemin Industries, Inc., Des Moines, IA; n = 489 cows; 13 experimental units). Treatments were initiated at approximately 37 d pre-calving until weaning for a total of 250 ± 12 d. Cows were enrolled in the 7-d CO-Synch+CIDR fixed-time artificial insemination (TAI) protocol followed by natural service for a 70-d breeding season. Pregnancy diagnosis was performed by ultrasonography at 55 d after TAI protocol and 40 d after the end of the breeding season. Cow body weight (BW) and body condition score (BCS) were recorded at initiation of the TAI protocol (d -10), at pregnancy diagnosis (d 55 and 110), and at weaning (d 285). Within group, mineral disappearance was determined by the difference in weight between offered mineral and refusals. Data were analyzed using the GLIMMIX and MIXED procedures of SAS with pasture/group as the experimental unit with the effect of treatment and included group (treatment × location), cow (group), and location as random variables. Age, DPP, d -10 BCS, and BW were similar (P > 0.05) between treatments (5.4 and 5.3 ± 0.61 yr, 79.2 and 79.9 ± 4.61 d, 5.1 and 5.2 ± 0.05, 515.7 and 515.6 ± 15.11 kg for Control and CrP, respectively). Mineral disappearance was similar (P = 0.999) between treatments (165.5 and 152.9 gּ animal-1ּ d-1, for Control and CrP, respectively). Cow BW was similar (P > 0.05) between treatments on d 55, 110 and 285 (558.5 and 551.4 ± 14.50 kg, 580.8 and 594.6 ± 13.51 kg, and 574.2 and 570.9 ± 14.32 kg for Control and CrP, respectively). Similarly, cow BCS did not differ (P > 0.05) between treatments on d 55, 110 and 285 (5.4 and 5.4 ± 0.09, 5.3 and 5.3 ± 0.10, and 5.1 and 5.2 ± 0.10 for Control and CrP, respectively). Calf birth and weaning BW were similar (P > 0.05) between treatments. However, CrP-supplemented cows tended (P = 0.081) to have greater estrus expression (60.2 and 68.3 ± 3.1 %, for Control and CrP, respectively) and CrP-supplemented cows had greater (P = 0.045) TAI pregnancy rate when compared with Control cows (49.9 and 55.2 ± 2.1 %). Supplementation of Chromium Propionate to beef cows from pre-partum through weaning did not affect cow BW and BCS, tended to increase estrus expression and increased TAI pregnancy rate.

100 Impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to embryo transfer

Abstract This study aimed to evaluate the impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to fixed-timed embryo transfer (FTET). Postpartum beef cows (n = 763) from 22 locations were exposed to a 7-d Select Synch + controlled internal drug releasing (CIDR) and breeding indicator patches were affixed upon CIDR removal. Estrus expression was assessed twice daily for 72 h and a 100-µg injection of gonadotropin-releasing hormone was administered to cows that failed to express estrus 72 h after CIDR removal. Brightness mode ultrasonography of the corpus luteum (CL) was conducted to select recipients for FTET 9 d after CIDR removal. Suitable recipients were assigned to receive a single fresh or frozen embryo derived from either in vitro (IVF) or in vivo (IVD) method. After embryo recipient selection, CL morphometries and blood perfusion (BP) were then assessed at the time of embryo transfer via transrectal ultrasonography. Embryo recipients were categorized according to CL area [small (< 3 cm²), medium (3 to 4 cm²), or large (> 4 cm²)] and based on the percentage of luteal area with blood perfusion signals [low (< 25%), medium (25 to 45%), or high (> 45%)]. Pregnancy diagnoses were performed between d 60 and 90 of gestation. Cows that failed to express estrus prior FTET had decreased (P ≤ 0.02) luteal area, luteal diameter, and pregnancy rates compared with cows that expressed estrus. Luteal area category had no effect (P = 0.61) on pregnancy rates. Embryo recipients that expressed estrus had similar (P = 0.12) luteal blood perfusion compared with recipients that failed to express estrus. Embryo recipients with high (P = 0.02) and medium (P = 0.05) BP had greater pregnancy rates compared with embryo recipients with low BP. There was no interaction between estrus expression and luteal BP (P = 0.84). In summary, estrus expression and luteal BP positively impacted pregnancy rates to embryo transfer and may be used to facilitate embryo recipient selection.

Reproductive outcomes of prepubertal Bos indicus beef heifers raised in a pasture-based feeding system submitted to ovulation induction strategies prior to a timed-artificial insemination protocol

Reproductive outcomes were evaluated in Nelore (Bos indicus) heifers submitted to one, two or no ovulation induction protocols based on progesterone (P4) and estradiol (E2) prior to a timed-artificial insemination (TAI) protocol. A total of 1,437 heifers (13.0 ± 0.8 mo old; 3.1 ± 0.1 of body condition score [BCS] and 279.9 ± 25.8 kg of body weight [BW]) were randomly assigned to 1 of 3 treatments: 0IND (n = 486): no ovulation induction protocol; 1IND (n = 481): one ovulation induction protocol; or 2IND (n = 470): two ovulation induction protocols. On Day −47, heifers from 2IND received a disinfected intravaginal P4 device (2 g, previously used for 21 d), kept until Day −40, when 0.5 mg of E2 cypionate (EC) was given. On Day −19, heifers from 2IND and 1IND underwent the same protocol. On Day 0, all heifers were submitted to the same TAI protocol, starting with a P4 device (0.5 g), 0.5 mg of cloprostenol sodium (PGF), and 1.5 mg of E2 benzoate. On Day 7, P4 device was removed, 0.5 mg of PGF, 0.5 mg of EC, and 200 IU of equine chorionic gonadotropin (eCG) were administered. The TAI was performed 2 d later (Day 9). Blood samples were collected on Days −47 and 0, to determine the presence of CL (circulating P4 concentrations ≥ 1.0 ng/mL). Ultrasound was performed on Days 40, 75 and between Day 150 and parturition to assess pregnancy per AI (P/AI) and pregnancy loss (PL). Statistical analyses were performed using SAS 9.4 (a-cP ≤ 0.05; A,B0.05 < P ≤ 0.10). The proportion of heifers with CL on Day −47 was similar among groups (3.4%). A greater proportion of heifers from 1IND had CL on Day 0, followed by 2IND, then 0IND (87.9a; 80.4b; 28.8c%). There was an effect of treatment on expression of estrus (2IND: 66.6a; 1IND: 67.2a; 0IND: 57.4b%), P/AI on Day 40 (2IND: 53.4a; 1IND: 43.9b; 0IND: 46.5b%), P/AI on Day 75 (2IND: 49.8a; 1IND: 40.5b; 0IND: 44.4ab%) and final P/AI (2IND: 45.5a; 1IND: 35.8b; 0IND: 40.5ab%). No differences were observed in PL (40–75 = 6.3%; 75-final = 9.6%; Total = 15.3%). Particularly within lighter heifers, there was an effect of treatment on P/AI on Day 40 (0IND: 39.2b; 1IND: 43.3ab; 2IND: 53.9a%) and on Day 75 (0IND: 36.6B; 1IND: 39.0AB; 2IND: 48.5A%). At the first pregnancy diagnosis, more nonpregnant heifers from 2IND had CL on Day 40 than 0IND, but 1IND did not differ from the other groups (85.4a; 74.8b; 80.8ab%). In conclusion, ovulation induction protocols performed prior to the TAI protocol increased the proportion of heifers with CL on Day 0. The use of two induction protocols resulted in greater fertility, particularly in lighter heifers, and increased cyclicity among nonpregnant heifers. These results indicate that this strategy may be an optimized method for inducing cyclicity and enhancing fertility of prepubertal Nelore heifers raised in pasture-based feeding systems.

Comparison of two intravaginal progesterone-releasing devices in lactating Holstein cows synchronized with a 5-d GnRH-based timed-AI protocol

The objective of the study was to compare the effectiveness of CIDR vs. PRID-Delta devices for use in a 5-day Ovsynch protocol for TAI in lactating Holstein cows that were either not in estrus after the end of the voluntary waiting period or non-pregnant and not returning to estrus following the previous AI. Cows fitted with a collar-mounted automated activity monitoring system (Alta Cow Watch) were subjected to a standard 5-d Ovsynch protocol [100 μg of gonadorelin (GnRH) on Day 0 and 500 μg of cloprostenol on Days 5 and 6] and allocated randomly to receive either an intravaginal device containing 1.35 g (CIDR; n = 304) or 1.55 g (PRID ® DELTA; n = 304) of progesterone between Day 0 and 5. All cows received a second administration of GnRH at approximately 56 h and timed-AI (TAI) 72 h after intravaginal device removal. Inseminations were done using conventional frozen-thawed semen. Estrus events prior to TAI were recorded and transrectal ultrasonography was done on Day 0 to determine presence of a corpus luteum (CL) and 33 and 61 d post-TAI, respectively, to diagnose and confirm pregnancy. Cows had an average of 2.2 lactations, 124.3 days in milk, and a milk yield of 43.6 kg/d at enrollment. The overall percentage of cows with a CL at initiation of treatment was 68.8 % and did not differ between treatment groups. Cows with a CL had greater pregnancy per AI (P/AI) at 33 and 61 d post-TAI than cows without a CL (P < 0.01; 46.9 and 42.3 % vs. 32.1 and 27.4 %, respectively). The overall percentage of cows that expressed estrus prior to TAI was 24.8 % and did not differ between treatment groups; however, estrus expression prior to TAI affected P/AI at 33 and 61 d post-TAI (P < 0.01; 53.6 and 49.0 % vs. 38.5 and 33.9 % for those expressing or not expressing estrus, respectively). Pregnancy per AI at 33 d post-TAI tended to differ between treatment groups (P = 0.08; 46.1 vs. 38.5 % for PRID and CIDR groups, respectively) and P/AI at 61 d post-TAI was greater (P < 0.01) for PRID-treated cows (43.8 %) compared to CIDR-treated cows (31.6 %). Thus, PRID-treated cows had lower pregnancy loss than CIDR-treated cows (P < 0.01; 5.0 vs. 17.9 %). Also, treatment with a PRID tended (P = 0.08) to result in fewer twin pregnancies (7.9 vs. 14.5 % for PRID and CIDR treated cows, respectively). In conclusion, lactating dairy cows subjected to a 5-d Ovsynch TAI protocol plus a PRID-Delta had greater P/AI at 61 d post-TAI, lower pregnancy loss between 33 and 61 d post-TAI, and fewer twin pregnancies compared to cows subjected to a 5-d Ovsynch protocol plus a CIDR.

Synchronization of Ovulation and Fixed Time Breeding in Tellicherry Goats

Background: Reproductive management of goats on large scale becomes difficult due to contributing reasons like poor estrus expression, lack of heat detection techniques, etc. Synchronization of ovulation has significantly improved the conception in cows. However, such investigations are lacking in goats. Hence, an experiment was conducted to compare the efficacy of different ovulation synchronization protocols on kidding and fecundity rates in Tellicherry goats during winter and summer seasons. Methods: The study was conducted in 240 does of 60 days postpartum period in two different seasons and investigated the efficacy of different protocols, The efficacy of intravaginal sponge (group I), Ovsynch (group II), Ovsynch with sponge (group III), Co synch (group IV), Co synch with sponge (group V) and control (group VI) on kidding and fecundity rate following fixed time breeding (NS/AI) was investigated in Tellicherry goats. Result: The overall kidding rate recorded during winter season in natural service (NS) was 80.00 and Artificial Insemination (AI) it was 70.00 per cent and in summer season it was 60.00 and 55.00 per cent, respectively. During winter season the fecundity rates observed were 1.70, 1.60, 1.75, 1.60, 1.60 and 1.40 in group I, II, III, IV, V and VI, respectively. The corresponding values during summer season were 1.55, 1.40, 1.60, 1.45, 1.50 and 1.10, respectively. From this study, the ovsynch with intravaginal sponge protocol found to be an effective protocol for ovulation synchronization in Tellicherry goats.

Effect of altrenogest treatment before weaning on reproductive performance and production efficiency in primiparous and multiparous sows

BackgroundMost sows will experience negative energy balance during lactation resulting in impaired follicular development. This study aimed to treat 28-day lactating sows with altrenogest (ALT) to suppress follicle enlargement during lactation, and to assess the estrus and reproductive performance post-weaning.MethodsIn this study, we conducted two trials. In trial 1, we monitored the follicular development of lactating sows including 10 primiparous sows and 10 multiparous sows during the whole lactation to confirm the ALT administration time. In trial 2, a total of 42 primiparous and 111 multiparous sows were allocated to three treatments: Ctrl (control group, n = 51): no treatment; TAI (timed artificial insemination group, n = 51): sows were injected with equine chorionic gonadotropin (eCG) after weaning 24 h and gonadotropin-releasing hormone (GnRH) when they expressed estrus; and AT-TAI (ALT treatment-timed artificial insemination group, n = 51): base on the process of TAI group, the sows were fed with 20 mg ALT per day before weaning 10 days. All sows were artificially inseminated twice at 12 h and 36 h after estrus. The follicle size changes and serum hormone levels were explored in this process.ResultsAlthough the follicle size of multiparous sows was larger than primiparous sows during the whole lactation (P < 0.05), similar change trends of follicle size were observed in primiparous and multiparous sows. Meanwhile, the FSH, LH and E2 levels of multiparous sows were higher than primiparous sows. The ALT treatment significantly inhibits the increase in follicle size (P < 0.05) and reduces the serum levels of FSH, LH and E2 (P > 0.05). Additionally, ALT treatment increases estrus concentration and the preovulatory follicle size (P < 0.05), meanwhile, it delays the weaning-to-estrus interval (WEI, P < 0.001). However, the estrus rate, pregnancy rate, total pigs born and born alive did not differ between treatments (P > 0.05).ConclusionsThere were significant differences in the size of follicles in the lactation between primiparous and multiparous sows. ALT treatment during the last ten days of lactation concentrated estrus expression leading to higher work efficiency of breeder in batch production, however, with no improvement in reproductive performance.

Efficacy of omitting initial GnRH in once-used CIDR co-synch protocol for the treatment of anestrus in buffaloes during low breeding season

Progesterone-based hormonal protocols are effective to treat anestrus in buffaloes. However, most of those protocols are costly, thus, requiring a cost-effective protocol that minimizes handling frequencies. This study, therefore, evaluated the effectiveness of the ‘once-used CIDR co-synch protocol’ with or without initial GnRH for treating anestrus in buffaloes during low breeding season. Anestrous buffaloes (n=29) were divided into two Treatment groups. As a part of the ‘once-used CIDR co-synch protocol,’ the first group (T1, n=18) received an initial GnRH on a random day (day 0) while the second group (T2, n=11) did not receive it. On day 0, the once-used CIDR device was inserted intravaginally in both groups, with GnRH administered in T1 but omitted in T2. On day 7, during CIDR removal, each buffalo received PGF2α, and on day 10, GnRH was given, and fixed-timed artificial insemination (FTAI) was done. Ovarian status was assessed on d0 and on 8 to 9-day post-FTAI using transrectal ultrasonography. Plasma progesterone concentrations on 8 to 9-day post-FTAI were determined using ELISA. No significant differences in estrus expression, ovulation and pregnancy rates were observed between two Treatment groups, with overall rates of 93%, 69%, and 34.5%, respectively. However, the overall pregnancy outcome (from FTAI plus natural breeding of buffaloes that returned to estrus) up to 2 months post-FTAI was 48.3%. Parity affected the ovulation among treated buffaloes, with higher (P=0.04) ovulation rate in buffaloes ≤4th parity (79.2%) compared to &gt;4th parity (20%). There were no differences in CL size and plasma progesterone concentrations during 8 to 9-day post-FTAI between two treatment groups. In conclusion, omitting the initial GnRH in ‘once-used CIDR Co-synch protocol’ proved equally effective as the protocol with initial GnRH for the treatment of anestrus in buffaloes during the low breeding season.

Influence of early progesterone removal on follicular development, expression of estrus, and pregnancy rates in presynchronized postpartum beef cows

The objective of this study was to evaluate the impact of early progesterone removal on pregnancy rates to fixed-time artificial insemination (FTAI) in presynchronized beef cows. Postpartum beef cows (n = 882) were randomly assigned to 1 of 2 treatments: 1) 7&7 Synch: cows received a controlled internal drug release insert (CIDR) and a 25-mg injection of prostaglandin F2α on day 0, 100 μg of GnRH on day 7, a second injection of prostaglandin F2α (PG2) at CIDR removal on day 14, and a second injection of GnRH at FTAI 60–66 h after PG2 (day 17); 2) 7&6 Synch: cows received the same treatment as 7&7 Synch; however, CIDR removal occurred in conjunction with PG2 on day 13, while FTAI remained at 60–66 h after CIDR removal (day 16). Ovarian ultrasonography was performed to determine follicle diameter at PG2 and FTAI in a subset of cows (n = 40). Cows exposed to the 7&7 Synch tended to have larger follicle diameter at PG2 compared with 7&6 Synch cows (P = 0.09); however, there were no differences in follicle diameter at FTAI. No differences were determined between treatments for the expression of estrus (7&7 Synch: 61.6 ± 5.30; 7&6 Synch: 54.1 ± 5.45; P = 0.31) or pregnancy rates to FTAI (7&7 Synch: 60.8 ± 3.83; 7&6 Synch: 57.0 ± 3.84; P = 0.42). In conclusion, early removal of progesterone did not impact pregnancy rates in presynchronized beef cows.

Association between body condition profiles, milk production and reproduction performance in Holstein and Normande cows

Body-condition dynamics are known to affect the different steps of reproduction in cattle (cyclicity, estrus expression, fertilization, embryo development). This has led to a widespread idea that there is an ideal-target optimal body condition, but no clear profile has yet been identified. Here we investigated the relationships between body condition score (BCS) profiles and reproductive performance in dairy cows. Data were from Holstein or Normande herds in 6 French experimental farms. In the Holstein breed, we discriminated 4 BCS profiles based on combining BCS at calving (Low: around 2.6 points, or High: around 3.3 points) with BCS loss after calving (Moderate (M): ≤ 1.0 points, or Severe (S): > 1.0 points). The Low-M profile mostly included multiparous cows with higher milk yield and lower reproductive performance than cows in the 3 other profiles. Low-M cows that experienced abnormal ovarian activity had lower reproductive performance than their profile-mates. Moreover, 67% of Low-M cows kept the same profile at the following lactation. The High-S profile mostly included primiparous cows with lower milk yield and higher reproductive performance than cows in other profiles. In High-S cows, higher milk yields correlated to higher risk of failure to calf on first insemination. Moreover, 38% of High-S cows kept the same profile at the following lactation, and none changed to Low-M. The other 2 BCS profiles (Low-S and High-M) were intermediate in terms of milk yield and reproductive performance. In Normande, we discriminated 3 BCS profiles based on combining BCS at calving (Low: around 2.6 points, or High: around 3.5 points) with BCS loss after calving (Flat (F): flat with no loss, Moderate (M): around 0.5 points, or Severe (S): around 1.0 point). The Low-M and High-S profiles included cows with similar performance, even though High-S-profile cows showed better but not significantly different milk yield and reproduction performance. The High-F profile included cows that were more likely to experience abnormal ovarian activity and fail at first insemination than cows in other profiles. More than 50% of Normande cows with 2 successive lactations kept in the same BCS profile at the next lactation. Even though a low BCS at calving combined with severe BCS loss (more than 1 point) after calving was found to increase reproductive failure, there was no evidence of an optimal BCS profile for reproduction in dairy cows, and reproductive success or failure is multifactorial.

Effect of a targeted reproductive management program based on automated detection of estrus during the voluntary waiting period on reproductive performance of lactating dairy cows

The objective of this experiment was to evaluate the effect on reproductive performance of a targeted reproductive management (TRM) program for first postpartum insemination (AI) that prioritized AI at detected estrus (AIE) by providing different intervals for estrus detection based on records of automated estrus alerts (AEA) during the voluntary waiting period (VWP). A secondary objective was to evaluate the association between occurrence of AEA during the VWP and reproductive performance. Lactating Holstein cows (n = 1,260) fitted with neck behavior monitoring sensors for detection of estrus were randomly assigned to a program that used all-timed AI (TAI) for first service (ALL-TAI; n = 632) or a TRM program that prioritized AIE and used TAI only for cows not detected in estrus (TP-AIE; n = 628). Cows in the ALL-TAI treatment received TAI at 76 ± 3 days in milk (DIM) after a Double-Ovsynch protocol. Cows in the TP-AIE treatment were eligible for AIE for 30 ± 3 or 16 ± 3 d after a 49 d VWP if at least one (n = 346) or no (n = 233) AEA were recorded from 15 to 49 DIM. Cows not AIE received TAI after an Ovsynch protocol with progesterone supplementation at 90 ± 3 or 76 ± 3 DIM if the cow had or did not have AEA during the VWP, respectively. Data were analyzed by logistic and Cox's proportional hazard regression. In the TP-AIE treatment, 69.3 % of cows received AIE and more cows with (83.3 %) than without (45.0 %) AEA during the VWP received AIE. Cows in the TP-AIE (69.0 ± 0.7 d) treatment had fewer days from calving to first AI than cows in the ALL-TAI (75.7 ± 0.8 d) treatment. The proportion of cows pregnant by 150 DIM (ALL-TAI = 59.1 % and TP-AIE = 56.0 %) and the hazard ratio (HR) for time to pregnancy (1.0 [95 % confidence interval: 0.9, 1.2]) did not differ between treatments and median days to pregnancy were 102 and 107 for the ALL-TAI and TP-AIE treatments, respectively. Overall, the ALL-TAI (42.3 %) treatment had more first service pregnancies per AI (P/AI) than the TP-AIE (29.0 %) treatment. Cows with AEA during the VWP had greater P/AI (42.5 % vs. 28.9 %), proportion of cows pregnant by 150 DIM (67.4 % vs. 47.0 %), and HR for time to pregnancy (1.6 [1.4, 1.9]) than cows without AEA during the VWP. We conclude that a TRM program that prioritized AIE based on AEA during the VWP led to a similar pregnancy rate and proportion of cows pregnant by mid-lactation than a program that used all-TAI with extended VWP despite fewer P/AI to first service. Also, expression of estrus during the VWP was associated with improved reproductive performance. Thus, AEA during the VWP could be used as a predictor of reproductive potential for TRM of lactating dairy cows.

Reproductive Activity of Socorro Island Merino Ewes and Their Crosses with Pelibuey under Heat Stress Conditions.

An experiment was carried out to evaluate the effect of spring and autumn seasons on the reproductive activity of Merino Socorro Island ewes and their crosses with Pelibuey under heat stress (HS) conditions in the tropics. All ewes (n = 80) were randomly assigned to one of two breeds during the first and second periods, respectively: (1) Twenty Socorro Island Merino ewes (SIM) and (2) 20 Pelibuey Crossbred ewes (PBC). Animals were fed the same diet and given water ad libitum. All statistical analyses were performed using SAS statistical software 9.12 procedures. In both seasons, a mean of more than 80 U of maximum THI was obtained, while in spring and autumn, the minimum THI exceeded 30 and 40 U, respectively. All animals were in oestrus and ovulated in both seasons. The frequency of animals in spring during the first 48 h of oestrus expression was greater (p < 0.05) than 48-55 h but similar (p > 0.05) than 55-65 h; in autumn during the first 48 h and 48-55 h were similar (p > 0.05), but different (p < 0.05) than 55-65 h. The duration of oestrus expression was longer in the spring than in the autumn (p < 0.05). The frequency of animals was higher (p < 0.05) in SIM than in PBC ewes during the first oestrus cycle (1-17 d) and was also higher (p < 0.05) in PBC than in SIM ewes during the second oestrus cycle (18-35 d). The SIM ewes produced more (p < 0.05) progesterone (P4) than the PBC ewes. During the sampling days of the oestrus cycle, more P4 was created in autumn than in spring (p < 0.05). Both breeds showed severe HS. In the future, ewes treated under assisted reproductive programs in the tropics may improve reproductive efficiency.

242 Comparison of GnRH administration day in the 7&amp;7 Synch versus 8&amp;6 Synch Protocol for fixed-timed artificial insemination in beef heifers

Abstract The research aimed to investigate the impact of reducing the time interval for progesterone exposure on the ovulatory follicle just before performing fixed-timed artificial insemination (FTAI). This was achieved by adjusting the timing of administering a gonadotropin-releasing hormone agonist (GnRH; specifically, 100 µg gonadorelin, known as Cystorelin). The study assessed the effectiveness of two estrous synchronization protocols, the “7 &amp; 7 Synch” and a modified protocol, by examining estrus expression (EE) and the resulting pregnancy rates (PR) following FTAI. The research utilized frozen conventional Angus semen from Select Sires, Inc. (Plain City, OH), and involved 66 Angus-cross heifers from the beef cattle research unit near Fayetteville at the University of Arkansas. To ensure consistency, the heifers were divided into two treatment groups based on their cyclicity status (CYC) and age. CYC status was determined by assessing a reproductive tract score (RTS) 1 wk before the synchronization process. RTS scores ranged from 1 to 5, with RTS 1-3 indicating pre- or peripubertal status and scores of 4 and 5 indicating cycling. Heifers with an RTS of 1 and 2 were excluded from the study before synchronization commenced. Both treatment groups involved the insertion of a controlled internal drug-releasing device (CIDR; specifically, Eazi-breed, containing 1.38 g of progesterone) into the vagina on d -14. Simultaneously, a prostaglandin F2α analogue (PGF; 500 µg cloprostenol sodium, known as Synchsure) was administered. In the first treatment group (7&amp;7), GnRH was administered on d -7, while in the second group (8&amp;6), GnRH was given on d -6. In both cases, PGF was administered on d 0 when the CIDR was removed, precisely 72 ± 1 h before FTAI, along with another dose of GnRH. Estrus expression (EE) was assessed during FTAI by examining Estrotect patches (Rockway Inc., Spring Valley, WI). EE was considered present when a patch had 50% or more of its color rubbed off, and it was deemed absent when less than 50% of the color had worn off. Pregnancy rates (PR) were determined through ultrasound examination on d 55. EE and PR were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC). Statistical differences were declared at α ≤ 0.05 and tendencies declared between 0.05 &amp;lt; P ≤ 0.1. Heifers on the 8&amp;6-d protocol had greater rectal temperatures at breeding compared with 7&amp;7-d heifers (P &amp;lt; 0.0001). AI pregnancy rates were greater in heifers on the 8&amp;6-d protocol compared with the heifers on 7&amp;7-d protocol (P = 0.625) with average pregnancy rates of 39.4% and 30.3%, respectively. Overall, pregnancy rate was greater as well for the 8&amp;6-d heifers compared with the 7&amp;7-d heifers (P = 0.044), with mean overall pregnancy rates of 78.8% and 54.5%, respectively.

Timed-artificial insemination protocols for Bos indicus beef heifers: Evaluation of protocol length and variations in prostaglandin F2α treatments

The aim was to compare reproductive outcomes of Nelore heifers submitted to timed AI (TAI) protocols, with 7 or 9 d of permanence of the intravaginal progesterone (P4) device and different times of prostaglandin F2α (PGF) administration, for first (n = 935) and second (n = 530) services. On Day −24, heifers without corpus luteum (CL) underwent a protocol for induction of ovulation. On Day 0, heifers received a P4 device (0.5 g) and 1.5 mg estradiol (E2) benzoate. In order for the TAI to be carried out on the same day, these treatments were performed 2 d later on the heifers treated with the 7-d protocol. Additionally, heifers received 0.5 mg PGF at different times, resulting in four experimental groups: 9dP4-PGFd9 (n = 365); 9dP4-PGFd7 (n = 369); 9dP4-PGFd0&9 (n = 364); 7dP4-PGFd0&7 (n = 367). These nomenclatures indicate for how many d the P4 device was kept and the specific day on which PGF was given. At P4 removal, all heifers received 0.5 mg E2 cypionate and 200 IU eCG, and TAI was performed 2 d later. Effects were considered significant when P ≤ 0.05 (superscript letters a,b) whereas a tendency was assumed when 0.05 < P ≤ 0.10. Groups 9dP4-PGFd0&9 and 7dP4-PGFd0&7 had lower percentage of heifers with CL at P4 removal. The diameter (mm) of the dominant follicle (DF) was affected by treatment at P4 removal (9dP4-PGFd9: 11.3 ± 0.3b; 9dP4-PGFd7: 11.8 ± 0.2ab; 9dP4-PGFd0&9: 12.6 ± 0.2a; 7dP4-PGFd0&7: 10.8 ± 0.2c) and at TAI (9dP4-PGFd9: 12.7 ± 0.3ab; 9dP4-PGFd7: 13.2 ± 0.2a; 9dP4-PGFd0&9: 13.4 ± 0.2a; 7dP4-PGFd0&7: 12.4 ± 0.3b). Expression of estrus (%) was affected by treatment (9dP4-PGFd9: 89.6a; 9dP4-PGFd7: 93.5a; 9dP4-PGFd0&9: 88.2ab; 7dP4-PGFd0&7: 85.6b). There were no differences among treatments for P/AI on Day 40 (30–35 d post AI), final P/AI (between Day 70 and parturition) and pregnancy loss (between Day 40 and final P/AI). When the permanence of the P4 device was compared, regardless of PGF treatments, 9-d protocols resulted in greater DF diameter at P4 removal and at TAI, and greater expression of estrus (90.4 vs. 85.6%) than the 7-d protocol. Despite that, the 7-d protocol resulted in greater P/AI on Day 40 (55.3 vs. 49.1%). In addition, there was an interaction between protocol duration and body weight, in which heavier heifers (≥ 307 kg) had greater P/AI when treated with the 7-d protocol, in comparison to 9-d. In conclusion, longer TAI protocols (9 d of P4 device duration) resulted in greater DF diameter and expression of estrus. However, the shorter TAI protocol (7 d of P4 device duration) produced greater P/AI on Day 40, particularly in heavier heifers. Within 9-d protocols, the additional dose of PGF on Day 0 or the anticipation of the PGF to Day 7 did not influence fertility.

Evaluation and Comparison of Therapeutic Efficacy of Various Hormonal Protocols in Anoestrus Buffalo Heifers of Semi-Arid Region

To assess and compare different hormonal protocols' treatment efficacy in anoestrus buffalo heifers in a semi-arid region. Forty buffalo heifers with a history of anoestrus were chosen randomly from the semi-arid region of Banaskanth and divided into four equal groups.Group-I: Heatsynch protocol (n = 10), Group-II Ovsynch protocol (n = 10), Group-III Doublesynch protocol (n = 10) and Group-IV Control (n = 10) are followed by artificial insemination at a predetermined period in treated buffalo heifers and insemination during spontaneous estrus in group-IV buffalo heifers. In Groups I, II, and III, the corresponding percentages of estrus induction were 90, 80, and 80 percent. Major symptoms such as edoema, erythema, dampness of vulva and estrus mucus secretion were present during the expression of estrus. Fifty percent of the buffalo heifers in Group IV displayed estrus at varying intervals. After three consecution services, Group II had the highest overall fertility rate (50%) followed by Group III (40%), Group I (30%), and Group IV (30%). In true anoestrus buffalo heifers, the Heatsynch, Ovsynch, and Doublesynch procedure can be applied with success to induce estrus. Buffalo heifers that follow the Ovsynch protocol may have a higher conception rate.

Deciphering Estrus Expression in Gilts: The Role of Alternative Polyadenylation and LincRNAs in Reproductive Transcriptomics.

The fertility rate and litter size of female pigs are critically affected by the expression of estrus. The objective of this study was to elucidate the regulatory mechanisms of estrus expression by analyzing the differential expression of genes and long intergenic non-coding RNAs (lincRNA), as well as the utilization of alternative polyadenylation (APA) sites, in the vulva and vagina during the estrus and diestrus stages of Large White and indigenous Chinese Mi gilts. Our study revealed that the number of differentially expressed genes (DEG) in the vulva was less than that in the vagina, and the DEGs in the vulva were enriched in pathways such as "neural" pathways and steroid hormone responses, including the "Calcium signaling pathway" and "Oxytocin signaling pathway". The DEGs in the vagina were enriched in the "Metabolic pathways" and "VEGF signaling pathway". Furthermore, 27 and 21 differentially expressed lincRNAs (DEL), whose target genes were enriched in the "Endocrine resistance" pathway, were identified in the vulva and vagina, respectively. Additionally, we observed that 63 and 618 transcripts of the 3'-untranslated region (3'-UTR) were lengthened during estrus in the vulva and vagina, respectively. Interestingly, the genes undergoing APA events in the vulva exhibited species-specific enrichment in neural or steroid-related pathways, whereas those in the vagina were enriched in apoptosis or autophagy-related pathways. Further bioinformatic analysis of these lengthened 3'-UTRs revealed the presence of multiple miRNAs binding sites and cytoplasmic polyadenylation element (CPE) regulatory aspects. In particular, we identified more than 10 CPEs in the validated lengthened 3'-UTRs of the NFIX, PCNX4, CEP162 and ABHD2 genes using RT-qPCR. These findings demonstrated the involvement of APA and lincRNAs in the regulation of estrus expression in female pigs, providing new insights into the molecular mechanisms underlying estrus expression in pigs.

15 Influence of early progesterone removal on follicular development, estrus expression, and pregnancy rates in presynchronized beef cows

Abstract The objective of this study was to evaluate the impact of early progesterone removal on pregnancy rates to fixed-time artificial insemination (FTAI) in presynchronized beef cows. Postpartum beef cows (n = 922; body condition score = 4.9 ± 0.77; days postpartum = 77.3 ± 20.77 d) from 7 locations were enrolled in a completely randomized design. Within location, cows were stratified by parity and days postpartum before being randomly assigned to 1 of 2 treatments: 1) 7&amp;7 Synch: Cows received a controlled internal drug release insert (CIDR) and a 25-mg injection of prostaglandin F2α (PG1; d 0). Cows received 100 μg of GnRH on d 7 and the CIDR was removed 7 d later, concurrently with a second prostaglandin F2α (PG2) injection (d 14). Cows received a second injection of GnRH and were FTAI 60-66 h after PG2 (d 17); 2) 7&amp;6 Synch: Cows received the same treatment as 7&amp;7 Synch cows; however, CIDR removal and PG2 were performed on d 13, and cows were FTAI 60-66 h after CIDR removal. Ovarian ultrasonography was performed to determine follicle diameter and CL presence at PG2 and FTAI in a subset of cows (n = 40). Estrus detection patches were utilized to evaluate estrus expression between PG2 and FTAI. Pregnancy diagnosis was performed 28-35 d after FTAI. Cows exposed to the 7&amp;7 Synch tended to have larger follicle diameter at PG2 compared with 7&amp;6 Synch cows (P = 0.09); however, there were no differences in follicle diameter at FTAI. Cows that expressed estrus tended to have larger follicle diameter at FTAI compared with cows that failed to express estrus (P = 0.10). Follicular growth between PG2 and FTAI, percentage of cows with a corpus luteum at PG2, and ovulation rate were not impacted by treatment (P ≥ 0.56). No differences were determined between treatments for estrus expression (7&amp;7 Synch: 77.1 ± 5.91; 7&amp;6 Synch: 74.6 ± 6.28; P = 0.50) or pregnancy rates to FTAI (7&amp;7 Synch: 60.1 ± 4.32; 7&amp;6 Synch: 58.2 ± 4.26; P = 0.69). In conclusion, early removal of progesterone did not impact pregnancy rates in presynchronized beef cows. Thus, the 7&amp;6 Synch protocol described herein may be used as an alternative to the conventional 7&amp;7 Synch protocol without compromising fertility.

130 Effect of an appeasing substance application on growth, stress, handling quality and reproduction of Bos indicus beef heifers synchronized to fixed-time AI

Abstract This experiment evaluated the effects of an analogue of bovine appeasing substance (BAS) on growth, stress, handling quality, and reproduction of Nellore heifers. Twenty-nine heifers [body condition score (BCS) = 4.84 ± 0.13; body weight (BW) = 371 ± 0.77 kg; 23 ± 2 months of age)] were assigned to 1 of 2 treatments: 1) Saline solution (0.9 NaCl; n = 14) or BAS (Secure Cattle, IRSEA Group, Quartier Salignan, France; n = 15). Both solutions were applied topically in the nuchal skin area (5 mL/heifers) at the beginning (d -9) of the fixed-time artificial insemination protocol (FTAI). Heifers were allocated in two different pastures according to the treatment (one pasture per treatment) for 15 d (time of action of BAS) and then combined in a single group (both treatments in the same pasture). Heifers were inseminated on d 0, and BW and BCS were collected on d -9 and 40. The temperament in the squeeze chute (entry and exit scores; scale 1 – 3; chute score; scale 1 – 5; greater values mean more reactive heifers) and blood samples were collected on d -9, 0, 7, 14 and 30. The percentual of aggression, accident, and dirtiness in the perineal region were evaluated on d 0 along with time to inseminate, estrus expression scores (scale 1 – 3; 1 = no expression, 2 = low expression, 3 = greater expression), and dominant follicle size. The corpus luteum size was measured on d 7 and 14, and the pregnancy and embryo size on d 40. The BAS vs. Saline-treated heifers tended to have greater BW change (23.6 vs. 20.8 ± 1.03 kg; P = 0.09) and had greater BCS change (0.05 vs. -0.21 ± 0.05; P &amp;lt; 0.01). The BAS vs. Saline-treated heifers tended to have lesser entry scores (1.42 vs. 1.67 ± 0.09; P = 0.09) and percentual of dirtiness in the perineal region (48.3 vs. 71.1 ± 8.67 %; P = 0.06), and no effects of treatment were detected (P ≥ 0.39) for chute score, exit score, aggression, accident and time to inseminate. The BAS vs. Saline-treated heifers had greater estrus scores (2.00 vs. 1.27 ± 0.21; P = 0.03), and no effects were detected (P ≥ 0.11) for ovarian variables, pregnancy rate, and conceptus size. Furthermore, no treatment effects were detected (P ≥ 0.25) for serum concentration of cortisol and plasma concentration of haptoglobin, ceruloplasmin, and progesterone. Therefore, BAS application at the beginning of the FTAI protocol could decrease the temperament and dirtiness in the perineal region and increase the growth and estrus expression of beef heifers.