Timed Artificial Insemination Research Articles

Comparison of ovsynch protocol with the additional GnRH administration during early and mid-luteal phase of ovsynch Protocol in crossbred cows

Background: The study was designed to compare ovsynch protocol with the additional GnRH administration during early and mid-Luteal phase of Ovsynch protocol with fixed time AI in crossbred cows. Methods: Thirty crossbred cows were allocated into three groups, Group I with an ovsynch protocol: Group II with an additional GnRH on day 6 after 2nd GnRH of Ovsynch and Group III with an additional GnRH on day 12 after 2nd GnRH of Ovsynch. The average number of services required per conception for Group I, Group II and Group III was found 2.40, 2.00 and 2.20 respectively and the conception rate was 50.0, 60.0 and 50.00 respectively. Result: The present study concluded that significantly (p

PSIII-8 The Effect of Pre-Breeding Vaccination with Modified-Live Virus or Inactivated Virus Vaccine on Body Condition and Reproductive Performance in Beef Cows

Abstract The objective of this study was to evaluate the effect of modified-live virus or inactivated virus vaccines on beef cow performance characteristics. Modified-live virus vaccines have broader immune system stimulation and longer effective duration than inactivated virus vaccines. The subsequent impact on cow performance, particularly reproduction, in well-managed herds is not well understood. Primiparous and multiparous cows (n = 877), from 3 herds, were stratified by age, body condition score (BCS), and body weight (BW) and randomly assigned to 1 of 2 treatments; 1) modified-live virus (MLV, 2-mL of Bovi-Shield GOLD FP 5 L5) and 2) inactivated virus (IV, 5-mL of CattleMaster GOLD FP 5 L5). Single dose vaccine administration occurred 42 d pre-breeding, before initiation of a 7-d CIDR-PG timed artificial insemination (TAI) protocol. Ten days following TAI cows were exposed to herd bulls for 60 d. Pregnancy assessment occurred 30 and 100 d post-breeding by rectal ultrasound. Cow BW and BCS were analyzed using PROC MIXED while reproductive performance variables were analyzed using PROC GLIMMIX of SAS 9.4. There were no differences (P ≥ 0.48) observed in BW or BCS at AI, pregnancy assessment 1, or pregnancy assessment 2 between cows receiving MLV or IV vaccine. No differences (P = 0.55) were observed in TAI pregnancy rate between cows receiving MLV or IV (66 versus 63%, respectively). Overall pregnancy rate did not differ (P = 0.71) between MLV (89%) and IV (90%) vaccines. Additionally, pregnancy loss from pregnancy assessment 1 to pregnancy assessment 2 was not different (P = 0.55) between MLV and IV. In this experiment, pre-breeding vaccine type did not impact cow BW, BCS, or reproductive performance. Overall, these results indicate that either MLV or IV vaccines can be utilized 42 d prior to breeding in beef herds with previous use of modified-live virus vaccines.

179 Sire Distribution of Calves in a Herd with use of Fixed Time Artificial Insemination Followed by Immediate Bull Exposure for Natural Service

Abstract Use of fixed time AI followed by immediate exposure of females to bulls for natural service can be a useful management strategy for commercial cow-calf producers to limit labor and time related to bull turnout as well as increase pregnancy rates earlier in the breeding season. Considering potential influence of factors such as bull fertility and time to and length of estrus in females, expectations for outcomes in natural service sire versus AI sire parentage is relatively unknown. We hypothesized that of calves born in the first 14 d of the calving season, less than 5% would be sired by natural service bulls exposed to females immediately following fixed time AI. Heifers (n = 191) and cows (n = 156) were synchronized and inseminated using the 7-d CO-Synch + CIDR fixed time AI protocol. All females were inseminated by the same AI technician using a single sire for heifers and a different single sire for cows. All females were exposed to bulls immediately following insemination. DNA was collected from a random subset of calves (Calves born from heifers n = 59; Calves born from cows n = 89) born in the first 14 d of the calving season for parentage analysis to estimate the overall percentage of calves sired by AI and natural service. Chi-Square tests were used to determine if the percentage of calves actually sired by natural service differed from the hypothesized 5% or less. Among calves born from heifers, the actual percentage sired by natural service (5.1%; n = 3/59) was similar (P = 0.98) to our hypothesized percentage. Among calves born from cows, the actual percentage sired by natural service (14.6%; n = 13/89) was greater (P < 0.001) than our hypothesized percentage of 5%. If commercial producers use fixed time AI followed by immediate bull exposure in cows, natural service bulls may sire more calves early in the calving season than expected.

Effect of Ovarian Status on Reproductive Performance in Dairy Heifers Inseminated with Sexed Semen

Background: The intensive reproductive management in the dairy farms requires inclusion of a large group of replacement heifers in the breeding program for a shorter period. In this aspect, a creation of effective estrus synchronization protocols with timed artificial insemination (TAI) by sexed semen and optimization of the current ones have a crucial role for obtaining high pregnancy rate. These protocols are beneficial, because they led to reduced interval to first AI, lack of need for estrus detection, and allow obtaining a large group of female calves for on time. Because of limited fertilizing potential of sexed spermatozoa this type of semen is applied mainly for heifers, as fertility is higher compared to lactating cows. The main objective of the present study was to investigate the effect of ovarian status on the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Materials, Methods & Results: Forty-eight Holstein healthy heifers separated in 2 groups were subjected to PGF2α-GnRH pre-treatment and Ovsynch or PRID-5-day estrus synchronization protocol and timed artificial insemination (TAI) with sex-sorted semen, staring 6 days after end of the hormonal pre-treatment. The ovarian status (presence of follicles with or not a corpus luteum) of the heifers at the begin of the treatment, on day of TAI and pregnancy rate in different groups were determined and compared. Additionally, the ovarian status at the begin of the treatment, ovarian status and size of preovulatory follicle (PF) on day of TAI and total values for both groups according to reproductive performance (pregnant or non-pregnant) were also analyzed. On day of TAI the animals with PF and a lack of corpus luteum (CL) in both groups were more that those with PF and CL (39.3% and 30% vs. 60.7 % and 70%), with significant (P < 0.05) difference in PRID-5-day group. The pregnancy rate tended to be higher in PRID-5 day than Ovsynch treatment (65% vs. 35.7%). A higher percentage (100% and 67.9%) of the pregnant animals in both treatments had not CL on day of TAI, and the size of the PF (1.58 ± 0.12 cm and 1.64 ± 0.13 cm) was increased (P < 0.05). Similar effects of the ovarian status on reproductive performance were obtained after a comparison of the total values between pregnant and non-pregnant animals. The percentage of heifers with observed PF without CL on day of TAI was significantly greater (P < 0.05) in pregnant compared to non-pregnant group (91.3% vs. 40%). The opposite dependence was determined for the parameter presence of follicles and corpus luteum (8.7% vs. 60%; P < 0.05). Furthermore, the size of the PF measured immediately before TAI was increased in animals became pregnant (1.60 ± 0.12 cm vs. 1.34 ± 0.17 cm; P < 0.05). Discussion: The analysis of the obtained results showed that the ovarian status on day of TAI affects the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Hormonal pre-treatment with onset of PRID-5-day protocol 6 days later and TAI with sex-sorted semen ensure acceptable pregnancy rate. The greater preovulatory follicle and a lack of corpus luteum before insemination provide significantly (P < 0.05) more pregnant animals, compared to the cases when CL is presented. Ultrasound determination of the ovarian function before insemination can be used in selection of heifers for TAI with sex-sorted semen. Keywords: heifers; estrus synchronization; sexed semen, pregnancy.

A Non-Synonymous Point Mutation in a WD-40 Domain Repeat of EML5 Leads to Decreased Bovine Sperm Quality and Fertility.

This study is part of a concerted effort to identify and phenotype rare, deleterious mutations that adversely affect sperm quality, or convey high developmental and fertility potential to embryos and ensuing progeny. A rare, homozygous mutation in EML5 (EML5 R1654W ), which encodes a microtubule-associated protein with high expression in testis and brain was identified in an Angus bull used extensively in artificial insemination (AI) for its outstanding progeny production traits. The bull’s fertility was low in cross-breeding timed AI (TAI) (Pregnancy/TAI = 25.2%; n = 222) and, in general, AI breeding to Nellore cows (41%; n = 822). A search of the 1,000 Bull Genomes Run9 database revealed an additional 74 heterozygous animals and 8 homozygous animals harboring this exact mutation across several different breeds (0.7% frequency within the 6,191 sequenced animals). Phenotypically, spermatozoa from the homozygous Angus bull displayed prominent piriform and tapered heads, and outwardly protruding knobbed acrosomes. Additionally, an increased retention of EML5 was also observed in the sperm head of both homozygous and heterozygous Angus bulls compared to wild-type animals. This non-synonymous point mutation is located within a WD40 signaling domain repeat of EML5 and is predicted to be detrimental to overall protein function by genomic single nucleotide polymorphism (SNP) analysis and protein modeling. Future work will examine how this rare mutation affects field AI fertility and will characterize the role of EML5 in spermatogenesis.

Improved fertility following a gonadotropin-releasing hormone treatment on day 2 of an estradiol and progesterone-based timed-artificial insemination protocol in lactating dairy cows

The present study evaluated the addition of gonadotropin-releasing hormone (GnRH) concomitant or 2 d after the beginning of protocols initiated with estradiol benzoate (EB). A total of 459 multiparous and 371 primiparous lactating Holstein cows were enrolled in the study. Weekly cohorts of cows were randomly assigned to 1 of 3 experimental groups that differed in the strategy to initiate the timed AI (TAI protocol. On d 0, all cows received a 1.55-g progesterone (P4) implant. Additionally, cows in the EBd0 group received 2 mg of EB i.m.; cows in the EBd0-GnRHd0 group were treated simultaneously on d 0 with 2 mg of EB plus 100 µg of gonadorelin diacetate tetrahydrate (GnRH) i.m.; and cows in the EBd0-GnRHd2 group received 2 mg of EB on d 0 and 100 µg of GnRH 48 h later (d 2). The remaining treatments in the protocol were similar among groups and included 0.53 mg (i.m.) of cloprostenol sodium (PGF2α) on d 7, followed by a second PGF2α treatment on d 9 (at the time of P4 implant withdrawal) and 1 mg of estradiol cypionate i.m. Then, TAI was performed on d 11 (48 h after P4 removal) in all experimental groups. We detected an effect of treatment on pregnancy per AI (P/AI) on d 30, in which cows from the EBd0-GnRHd2 group demonstrated greater fertility than EBd0 cows, whereas cows in the EBd0-GnRHd0 group did not differ among EBd0 and EBd0-GnRHd0 (40.5 vs. 30.4 vs. 34.4%, respectively). In summary, GnRH treatment at the beginning of an estradiol and P4-based TAI protocol increased fertility only when GnRH was given on d 2. Moreover, a more pronounced positive effect of this strategy was observed in particular classes of cows: multiparous cows, cows with greater milk production, and those receiving the first service.

First-service pregnancy rate among beef heifers with different residual feed intake

The effect of residual feed intake (a measure of feed efficiency) adjusted for backfat thickness (RFIfat) on pregnancy rate (PR) was examined in Angus heifers over 2 yr. High- or Low-RFI heifers were timed artificially inseminated (TAI) with semen from High- or Low-RFI sires, respectively. There was a negative association (P < 0.05) between RFIfat value and PR in Year II for Low-RFI heifers. In Year I, the interaction between RFIfat and AI sires was significant in High-RFI heifers (P < 0.05) and tended to differ in Low-RFI heifers (P < 0.1). Therefore, selecting for feed efficiency may have negative consequences on fertility.

8 Efficacy of Sequential Estrus Synchronization and Timed Artificial Insemination Protocols in Beef Cattle

Abstract The objective of this study was to assess the efficacy of sequential estrous synchronization and timed artificial insemination (TAI) in beef cattle using transrectal ultrasonography (US) for pregnancy diagnosis 26d after the initial TAI (TAI-1;d0) to determine pregnancy status and eligibility for the second TAI (TAI-2) on d 29. Angus and angus cross primiparous and multiparous cows were randomly assigned to one of two treatment regimens; either single TAI (CON; n = 468) or two sequential TAI (RS; n = 473). Estrus was synchronized for both treatment groups using the 7-day CO-synch + CIDR protocol forTAI-1 at 60h - 66h post- Prostaglandin injection (PGf2α). A second 7-day CO-synch + CIDR protocol was initiated for RS groups on d 19 and pregnancy status determined by US coincident with CIDR removal on d 26 post TAI-1. Non-pregnant RS cows received an injection of PGf2α and Estrotect® estrous detection aid was applied. All non-pregnant cows received a second TAI (TAI-2) and GnRH injection 60-66h after PGf2α (day 29). The probability of pregnancy at 30d post TAI-2 was higher (P < 0.01) for RS (82%) than CON cows (56%). Overall pregnancy rate on d 120 post TAI-1 did not differ between treatments (92%; P < 0.823). The probability of pregnancy to AI on d 120 was higher (P < 0.0001) for RS (78%) than CON cows (50%). Conversely, the probability of pregnancy sired by natural service was higher (P < 0.03) for CON (41%) than RS (15%) by design. Mean fetal age at 120d pregnancy diagnosis did not differ (P < 0.5547) between treatments (RS, 94 days; CON ,96 days). In conclusion, re-synchronization for a second TAI beginning 19 d after the initial TAI increased total AI-sired pregnancies and has the potential to reduce the required number of natural service sires without negatively influencing calving distribution.

135 Vitamin E and Selenium Effects on White-tailed Deer Conception Success in Artificial Insemination Programs

Abstract The white-tailed deer breeding industry has developed into a $1.6 billion-dollar annual sector. However, even with this rapidly growing industry, little is known concerning certain mineral requirements for deer raised in confinement and their conception success. Previous research has suggested that white-tailed does are more apt to conceive with elevated circulating levels of zinc, vitamin E, and selenium. This research project consisted of ninety-three does on standard confinement diets, supplemented with only a single dose of Zn, Se, Mn, and Cu via MultiMin at the time of CIDR input. Supplementation of MultiMin was fixed across all animals in the study. These does were assessed by drawing blood at the time of artificial insemination (AI). Whole blood and serum samples were analyzed for micromineral levels (Co, Cu, Fe, Mn, Mo, Se, and Zn) and fat-soluble metabolites (vitamin A, vitamin E, and cholesterol) at Texas Veterinary Diagnostic Laboratory and analyzed using PROC REG in SAS. Conception success was determined by the does conceiving a fawn from from artificial insemination procedure which was verified via genetic testing of the fawn. It was found that the model containing the main effects vitamin E, zinc, and selenium along with their interactions of vitamin E by Zn and Se by Zinc was significant (P < 0.05; R2=0.15) on positively affecting conception success from artificial insemination. In particular, a tendency was detected in the relationship of vitamin E and selenium (P < 0.1). In post hoc analysis, parameter estimates from the regression were used, and selenium fixed at a level of 144 ng/mL is the point at which supplemental vitamin E has positive effects on conception from AI. This model shows that both vitamin E and selenium are required at higher levels than previously thought in confinement-reared white-tailed deer with intensive breeding programs. With further research using vitamin E and selenium, the mineral requirements of white-tailed deer in confinement can be better understood and aide producers in reproductive efficiency in their captive deer herds.

Effect ofpre-synchronisation with progestogen and eCG onreproductive activity insynchronised ewes during anoestrous season.

The objective ofthe study was toinvestigate the effect ofpre-synchronisation onthe occurrence oftheoestrus and pregnancy rate after fixed time artificial insemination (FTAI) insynchronised ewes during theanoestrous season. Kivircik ewes (n=84) were randomly assigned toone ofthe two treatment groups with (PRE; n=42) orwithout (SYN; n=42) pre-synchronisation. Inthe SYN group, the ewes were subjected toa7-d short-term protocol (P4insertion-6d-PGF2α-1d-P4 removal+ eCG). In the PRE group, the same short-term protocol asintheSYN group was applied with 7 days apart for a pre-synchronised synchronisation protocol. Acervical FTAI was performed with fresh semen at54h after sponge removal. Atthe beginning ofthe synchronisation protocol, theoestrous response (66.7% vs. 0.0%) and cyclicity rates (64.3% vs. 14.3%) based onprogesterone (P4) were higher inthe PRE group compared tothose inthe SYN group, respectively (P<0.01). However, the oestrous response after synchronisation was lower within 96h (57.1% vs. 95.2%; P<0.01) inthe PRE group compared tothat intheSYN group. Although the pregnancy rate after the FTAI was significantly (P<0.05) lower inthe PRE group (14.3%) than theSYN group (35.7%), the overall pregnancy rate after natural mating was not different (95.2%) between the groups. Inconclusion, the pre-synchronisation decreased the oestrous response leading toalower pregnancy rate after theFTAI inthesynchronised ewes during the anoestrous season. Thus, attention should bepaid totwo consecutive administrations ofeCG inapre-synchronisation and synchronisation protocol inewes.

Portal

Portal Nina Oteria (bio) In a dream, you could do that. Hug someone you haven't seen in years without crying.You could feel like you still lived in your old bedroom. You could go back to before likenothing, like magic, like the reverse of water down the drain. I wish I could have said what I wanted to then, but I was trying to hold back the windfrom my cheeks. The minute stretches long then time splits me into colors. Suspendedin time, we spin leaves before they hit the ground. Let's dance in front of the garage!Let's catch the frogs and the leaves and the neighbor's dog called Muffin. He sings inthe yard to the cat called Cookie to come on home in a low melodic tone. Time ain't nothing anyway, just dirt on the rug. You can brush it out of the way with aneyelash, out of the way with a word. You can visit me somewhere impossible and grandbut I'll look for you in the dining room, at the cherrywood table, Sunday at three. Youknow which chair, behind the hedges. I'll leave the garden light on for you. I'll wait aslong as I need to. The land demands us as we were. Innocent, loving, magnolia petalsoft, pine pungent. Resilient like air. [End Page 126] Nina Oteria nina oteria is a poet and artist from Raleigh, North Carolina. She paints, facilitates poetry workshops, and is one of the founding poets of the Corcoran Poetry Wall in Durham, North Carolina. Nina uses creativity to heal self and community. She holds an MFA in writing and a BA in religion. Copyright © 2022 Center for the Study of the American South

Comparison of estradiol benzoate doses for resynchronization of ovulation at 14 days after timed-AI in suckled beef cows

We aimed to compare the effects of use of 1 or 2 mg estradiol benzoate (EB) associated with an intravaginal progesterone (P4) device for resynchronization of ovulation 14 days after timed-AI (TAI) in suckled beef cows. Nelore cows were submitted to a TAI (D0) and on D14, received an intravaginal P4 device and were randomly assigned to EB-1 group [n = 516] or EB-2 group [n = 510], which that received 1 or 2 mg EB, respectively. Also, cows had the ovaries scanned by ultrasound to detect an active CL on D14. On D22, devices were removed and structural luteolysis was detected by color-Doppler ultrasonography. In cows which underwent luteolysis, the resynchronization protocol was continued and they were submitted to second TAI on D24. Pregnancy diagnosis was performed 30–35 days after first or second TAI. A subgroup [n = 18–19/group] was submitted to daily ovarian ultrasound scanning from D14 to D22. Proportion of cows with an active CL on D14 did not differ (P > 0.1) between EB-1 and EB-2 groups. The proportion of cows with an active CL on D22 and pregnancy per AI (P/AI) at first TAI were greater (P ≤ 0.05) in EB-1 (55% and 51%) than in EB-2 group (48% and 42%). The P/AI at second TAI did not differ (P > 0.1) between EB-1 (47% [106/227]) and EB-2 group (42% [110/259]). Cumulative pregnancy rate was greater in EB-1 (73% [370/508]) than in EB-2 group (64% [322/502]). No difference (P > 0.1) was observed in the proportion of non-pregnant cows with a synchronized follicular wave emergence between EB-1 and EB-2 groups. In conclusion, treatment with either 1 or 2 mg EB associated with an intravaginal P4 device at D14 after TAI are efficient to synchronize a new follicular wave emergence. The decreased P/AI from first TAI observed in the group of cows receiving 2 mg indicates that this dose is not recommended for use in resynchronization programs initiated 14 days after TAI. The use of 1 mg EB associated with a P4 device provides an elevated cumulative pregnancy rate after two TAIs with an interval of 24 days.

Economics of timed artificial insemination with unsorted or sexed semen in a high-producing, pasture-based dairy production system

This study used a stochastic simulation model to estimate the potential economic benefit of using timed artificial insemination (TAI) in combination with conventional unsorted (TCONV) and sexed (TSEX) semen in heifers only (TCONV-H, TSEX-H) and in both heifers and lactating cows (TCONV-HC, TSEX-HC) in a high-producing, pasture-based production system. The scenarios were compared with a conventional reproductive policy (CONV) in which heifers and cows were inseminated with conventional unsorted semen after estrus detection. Sensitivity analysis was also used to estimate the effect of hormone costs from TAI use on the profitability of each program relative to CONV. The mean annual (± standard deviation) profit advantage (ΔPROF) over CONV for TCONV-H, TCONV-HC, TSEX-H, and TSEX-HC scenarios were €3.90/cow ± 4.65, €34.11/cow ± 25.69, €13.96/cow ± 6.83, and €41.52/cow ± 42.86, respectively. Combined application of both technologies was shown to return a greater annual ΔPROF on average compared with that achievable from TAI alone. However, the risk of not returning a positive annual ΔPROF varied across the scenarios with higher risk in TCONV-H and TSEX-HC. Specifically, TCONV-H and TSEX-HC had a 24 and 18% chance, respectively, of not returning a positive annual ΔPROF. Sensitivity analysis showed that when hormone costs increased by €10/cow TCONV-H and TSEX-HC had a 38 and 23% chance, respectively, of not returning a positive annual ΔPROF. The range in ΔPROF for TCONV policies was most sensitive to the TAI pregnancy rate and TSEX policies were most sensitive to the relative fertility achieved with sexed compared with unsorted semen. This study has shown TAI and sexed semen are complementary technologies that can increase genetic gain and profitability in a pasture-based, dairy production system.

Effects of replacement of corn silage and distillers' grain diets with hay during prepartum on the health and production performance of dairy heifers postpartum.

In this study, we aimed to comprehensively evaluate the effects of prepartum replacement of corn silage and distillers' grain diets with hay on the postpartum health and production performance in dairy heifers. Pregnant Holstein dairy heifers were randomly assigned to two groups and fed different diets with the same net energy and protein concentrations. The low corn silage plus hay (CH) group diet mainly contained oat hay (28.5%), corn silage (25%) and folium ginkgo (23%). The high corn silage plus distillers' grains (CD) group diet contained corn silage (53.5%), distillers' grains (5%) and folium ginkgo (18%). Dairy heifers were fed from the beginning of pregnancy to the end of the transition period. Calf birthweight, postpartum morbidity, milk production and reproductive performance were determined. Compared with the cows in the CH group, those in the CD group presented increased calf birthweight and a high risk of some postpartum disorders (p<0.05), particularly ketosis (37.63% vs. 24.54%) and retained placenta (9.41% vs. 3.92%). However, there was no difference between the groups in reproductive performance, including first timed artificial insemination (TAI) rate, date of TAI and conception rate of TAI. The lactation curves showed no difference in milk yield during the peak lactation period of primiparous cows between the CH and CD groups; the total milk production was 33.39kg and 33.19kg respectively. Notably, the time to peak milk production was delayed in the CD group. It can be concluded that replacing corn silage and distillers' grains with hay can reduce postpartum morbidity in dairy heifers and shorten the time to peak milk production.

Dynamic changes in gene expression during follicle development and the efficacy of four timed AI protocols in non-suckling female yaks (Bos grunniens)

The objectives of the study were to investigate changes in the mRNA expression levels of five genes during antral follicle development and to assess the efficacy of four timed-artificial insemination (TAI) protocols in female yaks (Bos grunniens). RT-qPCR analysis revealed that expression levels were greater for follicle-stimulating hormone receptor and bone morphogenic protein 15 in the small follicle, luteinizing hormone receptor, and kit ligand in the large follicle, and growth differentiation factor 9 in the medium follicle (p < 0.05). Non-suckling yaks were treated as a 7-d CIDR, and PGF2α + eCG at CIDR withdrawal and TAI with frozen yak semen at 56–58 h after PGF2α (PPe-7d); either a 7-d CIDR (PPG-7d) or a 5-d CIDR (PPG-5d), and PGF2α at CIDR withdrawal and TAI + GnRH at 70–72 h after PGF2α; and GnRH treatment on Day 0, followed by PGF2α on Day 7 and TAI + GnRH on Day 9 (GPG-7d). The results showed that the pregnancy rate (P/AI) was greater in PPG-5d than in GPG-7d (p < 0.05), but the P/AI was not different among the other TAI protocols. In conclusion, the expression levels of these genes in follicles are dynamically changed during antral follicle development in yaks. The PPG-5d protocol achieved a greater P/AI.

The effect of subclinical endometritis on reproductive performance in postpartum Bos indicus multiparous beef cows

The objective was to investigate the prevalence of subclinical endometritis (SE) in postpartum Bos indicus multiparous beef cows using different polymorphonuclear cells (PMN) threshold ratios, and to evaluate the impacts of SE on their reproductive performance. A total of 689 postpartum Nellore cows (45.2 ± 7.8 days postpartum) were submitted to an estrus synchronization protocol + timed-artificial insemination (TAI). Endometrial cytology samples were collected by cytobrush before the beginning of the protocol. Cows were considered positive for SE if: (PMN) ≥ 3% (PMN3), PMN ≥ 5% (PMN5) and PMN ≥ 7% (PMN7). Pregnancy diagnosis was performed at 30 and 100 d after TAI. The prevalence of cows categorized as positive for SE increased (P < 0.05) as the threshold was lowered (PMN7 = 3.9%; PMN5 = 5.5%; PMN3 = 9.1%). Positive SE cows had similar (P > 0.41) BCS, days postpartum, and expression of estrus at TAI compared with negative SE cows. Positive SE cows had decreased (P = 0.04) pregnancy rates compared to negative SE cows in the PMN5 threshold (26.3 ± 8.7% vs 44.5 ± 4.1%); however, no difference (P > 0.45) was observed between positive and negative SE cows in the PMN3 and PMN7 thresholds. Embryonic mortality between days 30 and 100 was not affected by SE (P > 0.16). In conclusion, the prevalence of SE varies based on the PMN threshold used, whereas SE at the beginning of the TAI protocol decreased the pregnancy rates in postpartum Bos indicus beef cows when the PMN5 was used.

Conception rate according to antral follicle count and oestrus expression in Nelore cows submitted to timed artificial insemination

Context Antral follicle count (AFC) has been related to bovine fertility and response to reproductive biotechnologies, but its relationship to oestrus expression during timed artificial insemination (TAI) is not known. Aims This study evaluated the relationship between the AFC and oestrus expression in regard to the conception rate in beef cows that received an ovulation synchronisation protocol for TAI. Methods Multiparous Nelore cows up to 40 days postpartum were evaluated by an ultrasound to determine the AFC, and were classified into low (≤15 follicles; n = 150), intermediate (≥19 and ≤26 follicles; n = 150) and high count (≥30 follicles; n = 150). AFC evaluation was performed on a random day of the oestrous cycle (Day 0). The animals received a conventional TAI protocol based on progesterone and oestradiol benzoate. On Day 8, the animals received cloprostenol, equine chorionic gonadotrophin and oestradiol cypionate, in addition to a painting in the sacrococcygeal region. On Day 10, TAI was performed, and oestrus expression was evaluated and classified as high, low or absent, according to the removal of paint. Pregnancy diagnosis was performed by ultrasound 30 days after TAI. The data were analysed using a generalised linear model and a binary logistic regression model (P &lt; 0.05). Key results Regardless of AFC, a high proportion of cows showed high oestrus expression (low 61.3%; intermediate 67.3% and high 58.7%) at the end of the TAI protocol. The conception rate was influenced by AFC (low 69.3% vs high 56.7%; P = 0.04) and oestrus expression (high oestrus: 67.3% vs no oestrus: 45.4%; P = 0.003). In addition, an interaction (P = 0.008) between AFC and oestrus expression showed that low AFC cows and high oestrus expression had the highest conception rate to TAI. Conclusion AFC and oestrus expression classification influenced the conception rate of Nelore cows in the TAI programme. In addition, the interaction of AFC with oestrus expression revealed that the best conception rate was observed in females with low AFC that expressed high-intensity oestrus. Implications The associated assessment of AFC and oestrus expression represents a strategy to increase the conception rate in TAI programmes in cattle.

Effect of different dry period duration on milk components and serum metabolites, and their associations with the first conception rate in multiparous Holstein dairy cows

The aims of the present study were to evaluate the effects of different dry period (DP) lengths on milk fat to protein ratio (FPR) and metabolic status – blood leptin, adiponectin and non-esterified fatty acids (NEFA) concentrations in dairy cows, and their associations with the result of the first timed artificial insemination (TAI). Cows were blocked either to short DP (SDP; 30±2 days; n=72) or conventional DP (CDP; 60±2 days; n=76). Milk FPR was calculated at 30 and 60 days in milk (DIM). Body condition score (BCS) was recorded at –60, –30, calving, and 60 DIM. Blood samples were obtained at –60, –30, –7, calving, +7, +30, and +60 DIM for serum metabolites measurement. TAI was implemented between 65–75 DIM for all cows. Milk FPR and its changes were statistically analysed using an independent sample t test. To assess the impact of time, the pattern of BCS, and serum metabolites on the result of the first AI, repeated measure ANOVA was used. Only FPR-30 DIM revealed significant difference between pregnant and non-pregnant cows in SDP group (P&lt;0.01). Reduced BCS loss was observed in the SDP group and followed by slightly higher probability of pregnancy at first AI (P=0.19). Leptin was not altered by shortening the DP (P≥0.1). Significant differences were observed in blood adiponectin prepartum (P&lt;0.001) and at +7 DIM (P&lt;0.01), as well as in NEFA at +7 and +30 DIM between the two groups (P&lt;0.05). Pregnant cows following the first AI had significantly high postpartum leptin concentrations (P&lt;0.05), high prepartum adiponectin (P≤0.001), and lower NEFA at +7 DIM (P&lt;0.01) in the SDP group. In conclusion, shortening the dry period caused reduced BCS loss postpartum and variations in serum metabolits that favoured the possibility of pregnancy at first AI.

Improvement of Fertility Rate Using Ovsynch and Biostimulation Protocols with Timed Artificial Insemination in Thari Cattle

Improvement of Fertility Rate Using Ovsynch and Biostimulation Protocols with Timed Artificial Insemination in Thari Cattle

Relationship between the timing of insemination based on estrus detected by the automatic activity monitoring system and conception rates using sex-sorted semen in Holstein dairy cattle.

We investigated the optimal timing of artificial insemination (AI) for achieving pregnancy according to the onset/end of estrus detected by an accelerometer system in Holstein cattle. The conception rates of conventional semen were used as a reference. The conception rate from AI of sex-sorted semen was higher at −4 to 4 h (57.1%) from the end of estrus than those at −12 to −4 h (37.7%) and 12–20 h (30.3%), whereas AI at 4–12 h showed an intermediate conception rate (47.4%). Conversely, conception rates were similar in AI performed between 0 and 32 h from the onset of estrus. Regarding conventional semen, the interval from the onset and end of estrus did not affect conception rates. The present results suggest that the time of the end of estrus is the better indicator of optimal AI timing for sex-sorted semen than the onset of estrus.