Intensity Of Estrus Research Articles

Reproductive Performance of Estrus Pattern in Bachaur Cows of Bihar

Background: The Bachaur is a medium sized draft purpose breed mostly present in Madhubani, Darbhanga and Sitamarhi districts of Bihar and presently the breed is at the verge of extinction. Since no data is presently available regarding the estrus pattern in these cows therefore, present study was designed to document the oestrus intensity, estrus cycle length, estrus behaviour and duration of estrus in these animals. Methods: The total of nine healthy breeding Bachaur cows aged 3 to 5 years were maintained under identical managemental conditions.The estrous cycles of nine animals was synchronized using Cloprostenol Sodium @ 500 mg I/M (Pragma®, Intas, India) in cycling Bachaur cows. Estrus was detected in the morning and evening for external signs of estrus, estrus behavior, intensity of estrus, estrus duration and estrous cycle length. Result: In the present study, mounting or mounted by other animals was observed in more than 70% and sniffing, tried to lick and Flehmen’s reaction was observed in about 66.67% of treated cows. The other parameters like bellowing, restlessness, milk yield reduction, frequent micturition and Flehmen’s reaction were recorded in 44.44%, 55.56%, 44.44%, 55.56% and 66.67%, of animals, respectively. The most appreciable physical sign of estrus recorded was intense swelling of vulva (in 88.89%) however hyperaemia of vulva, copious estrual mucous discharge, pronounced tonicity of uterus, completely dilated os cervix and presence of large palpable follicle on the ovary was observed in 44.44%, 55.56%, 66.67%, 77.78% and 66.67%, of cows respectively.

Machine Learning to Predict Pregnancy in Dairy Cows: An Approach Integrating Automated Activity Monitoring and On-Farm Data.

Automated activity monitoring (AAM) systems are critical in the dairy industry for detecting estrus and optimizing the timing of artificial insemination (AI), thus enhancing pregnancy success rates in cows. This study developed a predictive model to improve pregnancy success by integrating AAM data with cow-specific and environmental factors. Utilizing data from 1,054 cows, this study compared the pregnancy outcomes between two AI timings-8 or 10 h post-AAM alarm. Variables such as age, parity, body condition, locomotion, and vaginal discharge scores, peripartum diseases, the breeding program, the bull used for AI, milk production at the time of AI, and environmental conditions (season, relative humidity, and temperature-humidity index) were considered alongside the AAM data on rumination, activity, and estrus intensity. Six predictive models were assessed to determine their efficacy in predicting pregnancy success: logistic regression, Bagged AdaBoost algorithm, linear discriminant, random forest, support vector machine, and Bagged Classification Tree. Integrating the on-farm data with AAM significantly enhanced the pregnancy prediction accuracy at AI compared to using AAM data alone. The random forest models showed a superior performance, with the highest Kappa statistic and lowest false positive rates. The linear discriminant and logistic regression models demonstrated the best accuracy, minimal false negatives, and the highest area under the curve. These findings suggest that combining on-farm and AAM data can significantly improve reproductive management in the dairy industry.

Cloprostenol effect with and without male stimulation on oestrus synchronization in Peru guinea pigs.

Cloprostenol, a synthetic derivative of prostaglandin F2α, effectively triggers functional and morphological regression of the corpus luteum (luteolysis). In rural Peru, the guinea pig (Cavia porcellus) holds significance within the local economy and serves as a valuable protein source. Enhancing reproductive efficiency is crucial to achieve uniformity in weight, age, and litter size across commercial systems. Thus, our study aimed to evaluate the effect of cloprostenol with and without male stimulation on the onset, duration, and intensity of oestrus in Peru guinea pigs. A total of 128 guinea pigs (120 females and eight males) between 8 and 12 months of age, weighing between 800 and 1200 g, were distributed in cages of 15 females per treatment. Cloprostenol sodium (0 [control], 0.20, 0.25, and 0.30 mg/animal) was IM administered to the groups with and without male stimulation. Four isolated males in individual cages, different from the one used for the treatment, were considered to detect oestrus. The oestrus intensity was assessed by observing sexual behaviour signs such as restlessness, moaning, attempts to mount, pelvic elevation, loin stretching, and vulvar inflammation. The oestrus was manifested 2 days after the administration of cloprostenol sodium. At a dose of 0.30 mg/animal and with male stimulation, the earliest oestrus was observed at 46.9 h. There was a reduction in the oestrus duration (p < .05) in guinea pigs that received the three doses of cloprostenol sodium compared to the control group. The highest percentages of frank oestrus intensity (66.7%) were strongly associated with the administered doses of cloprostenol sodium (p < .01). In conclusion, the cloprostenol sodium administration was proper for rapid oestrus induction in Peru guinea pigs.

Estrous characteristics and steroid concentrations in Aceh cows (Bos indicus) after estrus synchronization using prostaglandin F2a

Abstract. Hafizuddin, Husnurrizal, Thasmi CN, Herrialfian, Salsabil NL, Siregar TN, Sutriana A. 2024. Estrous characteristics and steroid concentrations in Aceh cows (Bos indicus) after estrus synchronization using prostaglandin F2a. Biodiversitas 25: 322-328. This study aims to determine the estrous characteristics and steroid concentrations during estrus in Aceh cattle after estrus synchronization using prostaglandin F2a. This study involved 9 Aceh cows with good reproductive status, not pregnant, and has shown at least 2 regular cycles, which were divided into 3 treatment groups. The first group (GI) received a single injection treatment, the second group (G2) received a double injection treatment with an interval of 10 days, and the third group (G3) was also treatment double injection with an interval of 12 days. Symptoms and responses to estrus were reported descriptively, and the data collected on onset, intensity, and duration of estrus were analyzed using one-way analysis of variance followed by Duncan's test. The results showed that estrus symptoms were almost similar and estrus response was 100% in all three treatment groups. The onset of estrus in G1, G2, and G3 did not differ significantly (P&gt;0.05) with values of 68.00±18.33, 60.00±0.00, and 72.00±24.00 hours, respectively. The intensity of estrus in G1, G2, and G3 showed significant differences (P&lt;0.05) with scores of 3.00±0.00, 5.00±0.00 and 4.33±1.15, respectively. The duration of estrus showed no significant difference in G1, G2, and G3 (P&gt;0.05) with durations of 32.00±18.33, 72.00±0.00, and 52.00±38.57 hours, respectively. The concentrations of estradiol and progesterone obtained also showed no significant differences (P&gt;0.05) in G1, G2, and G3, with respective concentrations of 91.67±24.77, 132.00±23.15, 89.47±24.19 pg/mL and 0.98±0.59, 0.86±0.18, 1.00±0.17 ng/mL. In conclusion, estrus synchronization with PGF2a single injection and double injection in Aceh cattle was found to have 100% estrus response. However, PGF2a with double injection showed higher estrus intensity compared to single injection. In Aceh cows, the recommended protocol for estrus synchronization using PGF2a is double injection.

Horário da inseminação artificial na taxa de prenhez das vacas Holandesas usando monitoramento automatizado de atividades

ABSTRACT: This study evaluated the probability of pregnancy and associated factors for two times artificial inseminations (AI), 8 or 10 hours after automated activity monitoring (AAM) alarm on the first postpartum AI of 1,054 Holstein dairy cows. The estrus was synchronized by prostaglandin or estradiol-progesterone program. Stepwise logistic regression was performed to analyze the probability of pregnancy, and associated factors (activity, estrus intensity, parity, peripartum health, retained placenta, postpartum vaginal discharge, and season). The highest pregnancy rates were obtained with multiparous animals, inseminated ten hours after the AAM alarm, in the fall or winter season, with a high activity peak and estrus intensity (P &lt; 0.05). Peripartum diseases, retained placenta, and postpartum vaginal discharge negatively influenced the pregnancy rate, regardless of parity. Thus, the optimization of AAM models by including on-farm measures like parity, peripartum health history, and environmental conditions may favor the correct identification of estrus and improve the AAM alarm regarding the ideal moment for AI, increasing the reproductive performance in dairy cows.

The Leptin Hormone Administration on the Estrus Intensity and the Appearance Time of Postpartum Estrus in Primiparous Bali Cattle

The Leptin Hormone Administration on the Estrus Intensity and the Appearance Time of Postpartum Estrus in Primiparous Bali Cattle

Influence of Blood Glucose, Total Protein and Haemoglobin at The Time of Induced Estrus on Conception Rate on Anestrus Crossbred Cows

The present study was conducted to evaluate the influence of blood glucose, total protein and haemoglobin at the time of induced estrus on conception rate in 30 postpartum anestrus crossbred dairy cows. The cows were treated with progesterone intravaginal (CIDR) based estrus induction protocol with double fixed timed inseminations at 12 and 24 h after injection of last GnRH. estrus induction response was 100% with majority of the cows (80%) showed intermediate intensity of estrus. On the day of first AI, blood was collected from all the animals for the estimation of glucose, total protein and haemoglobin. The mean time to onset of estrus from the time of removal of CIDR was 44.85 ± 7.23 h. The overall conception rate in the present study was 30 % (9/30). In the present study, the mean values of glucose, total protein and haemoglobin at the time of estrus were 43.81 ± 1.14 mg/dl, 7.78 ± 0.24 g/dl and 8.68 ± 0.22 g/dl respectively. The mean glucose, total protein and haemoglobin levels in the anestrus cows which were included in the study are lower than the normal range. There is no significant different in the biochemical parameters among the cows showing weak, intermediate and intense intensity of estrus. Similarly, there is no significant difference in the biochemical parameters between the cows that conceived and cows not has not conceived. The findings in the present study clearly indicates that poor nutritional status may be the cause for the anestrus condition of the animal under field conditions.

Occurrence of Postpartum Anestrus and Estrus Behaviour in Hormonal Treated Buffaloes of Jabalpur

The present study was conducted during June to December, 2022 at the Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science and Animal Husbandry, Nanaji Deshmukh Veterinary Science University, Jabalpur, Madhya Pradesh, India to study the occurrence of postpartum anestrus and compare the intensity of estrus in anestrus and estrus induced buffaloes of Jabalpur (M.P.). A total of 120 postpartum buffaloes (5–10 years of age) reared under field conditions in the Jabalpur district of Madhya Pradesh were surveyed. The buffaloes with a history of not showing signs of estrus for 60 days or more postpartum were considered as open animals for the study of the occurrence of postpartum anestrus. Gynaeco-clinical examination was also carried out to know the status of ovaries (presence of follicle or corpus luteum). These animals were randomly divided into four groups (three treatments and one control group) and each group had 06 anestrus buffaloes. Group I, II and III were treated with CIDR plus Ovsynch, CIDR plus Cosynch and eCG plus Cosynch protocols, respectively, while the control group (Group IV) animals were not given any treatment. The results revealed that the occurrence of postpartum anestrus in buffaloes was 69.10%. The percentage of postpartum buffaloes with 60–90 days, 90–150 days and more than 150 days postpartum were recorded to be 25.30, 45.78 and 28.91%, respectively. Irrespective of treatment groups, the overall estrus intensity ranged from 58–92 with a mean estrus intensity score of 70.58±2.89. Estrus intensity scoring is a good tool to describe the intensity of estrus which has a positive relationship with fertility.

Reduced period from follicular wave emergence to luteolysis generated greater steroidogenic follicles and estrus intensity in dairy cows

The onset of productive life in dairy cattle, concomitant to parturition, is accompanied by a substantial decrease in fertility in comparison with non-lactating, nulliparous heifers. Follicular growth patterns differ between parous and nulliparous dairy cattle. Nulliparous heifers ovulate follicles with reduced antral age (RAA). This study aimed to exogenously reduce ovulatory follicle age in lactating dairy cows from 7 to 5 days old. Cows (n = 80) had their estrous cycles synchronized with the Double-Ovsynch program. At the final portion of this program, luteolysis was induced at either 5 (RAA) or 7 (Control) days following follicular wave emergence. RAA outcomes were estimated in comparison with Controls. RAA resulted in smaller follicles 2 days post-treatment. Despite lower serum concentrations of 17β-estradiol before treatment compared with Controls, the rate of increase in this hormone was greater for the RAA treatment. There was no difference in luteolysis rates between treatments. Proestrus (luteolysis onset to estrus onset) was prolonged in RAA cows. Cows with RAA had more intense estruses. Collectively, these results indicate that decreasing the age of the ovulatory follicle may improve the steroidogenic capacity of the dominant follicle and estrus expression intensity in lactating dairy cows.

The Reproductive Performance of Local Sheep Following Induced Superovulation With Cattle Hypophisa Extracts

The aim of this study was to determine the effect of pituitary extract on estrous characteristics and the percentage of pregnancy in sheep. This study used a sample of 18 individuals. This study used 3 treatments 6 replications. The treatment used was the control treatment by giving 1 ml of PGF2α. Treatment 1 is by administering 1 ml of PGF2α, 1;0.5;0.25 ml of pituitary extract and 1 ml of PGF2α. Treatment 2 is by administering 1 ml of PGF2α, 2;1;0.5 ml of pituitary extract and 1 ml of PGF2α. The results showed that there was a very significant difference in the use of pituitary extract, this could affect the onset of estrus 0.00 (P&lt;0.01), and there was also a significant difference (P&lt;0.05) in the intensity of estrus.

Association between genomic daughter pregnancy rate and expected milk production on the resumption of estrus behavior in Holstein cattle

The objective of this observational study was to evaluate estrous expression at the first estrus occurring between 7 to 30 d in milk (DIM), as detected by an automated activity monitor (AAM), and its association with genomic daughter pregnancy rate (GDPR) and genomic expected milk production (GEM) in lactating dairy cows. A total of 4,119 lactations from 2,602 Holstein cows were included. Cows were enrolled as first lactation (n = 1,168), second lactation (n = 1,525) and third and greater lactation (n = 1,426). Hair samples were collected from the tail switch, and cows were genotyped using an SNP platform (Clarifide, Zoetis, São Paulo, SP, Brazil). Postpartum cows were examined daily by the farm personnel from calving until 10 DIM. Calving was classified as assisted (forced calf extraction) and unassisted (normal calving). Retained fetal membranes (RFM), hyperketonemia (KET), and left displaced abomasum (LDA) were also recorded. Mean GDPR (± SD) was -0.29 ± 1.4, and the intensity and duration of the first estrus event was 15.9 ± 13.1 x-factor (intensity unit measurement) and 11.1 ± 3.8 h, respectively. Cows that had greater GDPR had greater intensity and longer duration of estrus at the alert, independent of parity. Overall resumption of estrous expression, between 7 to 30 DIM, was 41.2% (1,695/4,119), where 58.8% (2,424/4,119) did not have an estrus event, 31.0% (1,274/4,119) of cows had one event of estrus, and 10.2% (421/4,119) of cows had 2 or more events of estrus early postpartum. Mean DIM (± SD) at first estrus event, detected by the AAM, was 19.4 ± 4.4 d. Days in milk at first event for cows with one event was 20.7 ± 1.6 d and 15.9 ± 3.1 d for cows with 2 or more events of estrus. First lactation cows were more likely to have an estrus event early postpartum when compared with second and third and greater lactation cows (45.2 ± 1.4% [530/1168] vs. 41.6 ± 1.3% [636/1525] vs. 37.2 ± 1.3% [529/1426], respectively). There was an interaction of parity and GDPR on the proportion of cows demonstrating an early postpartum estrus. There was no difference in the proportion of cows with an early postpartum estrus between those with assisted or unassisted calving, RFM, or LDA. However, cows that had KET were less likely to have an alert early postpartum when compared with cows that did not have KET. Mean genomic expected milk production (± SD) was 256.8 ± 600.1 kg. There was no interaction between GEM and parity on estrous expression (i.e., intensity and duration). There was no interaction between GEM and GDPR on the proportion of estrus early postpartum.

PSII-12 Influence of Dietary Methionine and Guanidinoacetic Acid on Estrous Cycles and Early Pregnancy in Beef Heifers

Abstract Interest is growing in methods to apply precision nutritional supplements strategically during the peri-conceptual period to enhance progeny performance of beef females. Studies where supplemental methionine (MET) was provided to bovine females in the peri-conceptual period demonstrated epigenetic modifications in muscle of the progeny. Guanidinoacetic acid (GAA) has been fed directly to livestock to increase creatine synthesis, but has not been evaluated for use in fetal programming. We fed MET and GAA to cross-bred heifers during the peri-conceptual period as a 2 x 2 factorial design to influence carcass characteristics of their steer calves. It was, therefore, important to determine if the interactions of dietary MET and GAA in the peri-conceptual period would alter reproductive efficiency. The null hypothesis was that these supplements would not alter reproductive efficiency of beef heifers when fed in the peri-conceptual period. Heifers were divided into four breeding groups for management purposes. On day -63, heifers (n = 20/diet, age = 384.1 ± 1.1 d) were assigned HeatTime collars and individually fed MET (10 g/d), GAA (40 g/d), the combination (MET + GAA), or ground corn carrier (CON) for 126 days. On day -9, heifers received 100 mg of gonadotropin releasing hormone and a CIDR. On day -2, the CIDR was removed and luteolysis was initiated with 25 mg of prostaglandin F2a. All heifers were inseminated with male sexed semen from a single sire and administered a second 100 mg injection of gonadotropin releasing hormone on day 0. On day 63, a blood sample was collected from all pregnant heifers (CON n = 10; MET n = 8; GAA n = 7; MET + GAA n =10) to evaluate circulating progesterone concentrations. Reproductive tracts were collected to determine CL weight, gravid uterine weight, and placentome number. Data were analyzed using the MIXED procedure of SAS with group, MET, GAA, and the interaction of MET and GAA as fixed effects. Days to first estrus were greater and number of estrus events prior to synchronization were fewer in CON heifers compared with supplemented heifers (P &amp;lt; 0.05). Luteal weight tended to be greater in heifers supplemented with MET compared with CON and GAA heifers (P = 0.09), but peak intensity of estrus, concentration of progesterone at day 63 of pregnancy, gravid uterine weight, and placentome number did not differ due to diet (P &amp;gt; 0.10). Supplementation with MET or GAA may improve onset of puberty but does not negatively alter reproductive performance in cross-bred beef heifers. These supplements can be used for fetal programming of muscle development in steer progeny without negatively impacting reproductive performance in the breeding herd. USDA is an equal opportunity provider and employer. Funded in part by USDA-NIFA-AFRI # 2022-67015-36196.

Effects of semen quality on pregnancy rate in artificially inseminated dairy cows

The study aimed to evaluate the quality of fresh and frozen-thawed semen of five adult Holstein-Friesian crossbred bulls and the pregnancy rate of cows inseminated with frozen semen of those bulls. The fresh semen of breeding bulls collected for artificial insemination (AI) programme in the field was of good quality with volume (6.7 ± 0.2 ml - 8.9 ± 0.5 ml), concentration (904.2 ± 56.4 million/ml), mass activity (3.3 ± 0.2-3.6 ± 0.2), total motility (77.0 ± 1.1% – 92.1 ± 0.6%), progressive motility (67.0 ± 1.2% – 87.4 ± 0.6%) and semen viability (73.0 ± 0.6% to 85.4 ± 0.7%). The computer assisted sperm analysis (CASA) results showed that diluted pre-freezing semen had good sperm total motility (50.1 ± 3.8 % to 59.0 ± 4.7%), progressive motility (30.0 ± 1.2%-39.0 ± 1.6%), the velocity traits of straight linear velocity (VSL), curvilinear velocity (VCL) and average path velocity (VAP) of sperm ranged from 48.0 ± 1.3 - 71.3 ± 0.7 μm/s,118.1 ± 2.8-181.3 ± 10.9 μm/s and 68.4 ± 2.5 to 91.0 ± 2.9 μm/s, respectively. Bull 1 showed significantly higher VSL (71.3 ± 0.7 μm/s), VCL (181.3 ± 10.9 μm/s) and VAP (91.0 ± 2.9 μm/s) compared to others. Viability of frozen-thawed semen was lower in Bull 5 (73.0 ± 1.71%) compared to others. Although in frozen-thawed semen these parameters declined, the semen was sufficiently good to be used in AI in the field. The overall pregnancy rate using frozen semen was 55.6% and the highest pregnancy rate (62%) was in cows that were inseminated with frozen semen of Bull 1, but the differences between bulls was not significant. The pregnancy rate had positive correlation with sperm count, total motility, progressive motility, VCL, VSL, VAP, amplitude of lateral head displacement (ALH), beat cross frequency (BCF), linearity (LIN), straightness (STR), sperm viability. In artificially inseminated cows, the intensity of oestrus of cows, timing of AI, site of semen deposition and season had a significant effect on pregnancy rate. In conclusion, the fresh and frozen-thawed semen of breeding bulls supplied in North-East Bangladesh for AI programme were good quality. Heat detection and insemination timing need to be improved to increase the pregnancy rate.&#x0D; Bangl. vet. 2022. Vol. 39, No. 1-2, 1–15

Effect of Vitamin A on Estrous Intensity, Number of Follicles, Follicles Diameter and Pregnancy Rate in Beef Cows

Moringa leaves are used as feed to increase the intensity of estrus. It is assumed that the positive effect on the Moringa leaves is due to the presence of vitamin A. This study aims to see the response of vitamin A as a supplement feed to the reproductive performance of beef cows including estrous intensity, number of follicles, follicle diameter, and pregnancy rate. The research was conducted in September-November 2022 in Lappariaja District, Bone Regency, South Sulawesi Province. 10 cows were used which were divided into 2 groups, each group consisting of 5 cows. Group 1 was the control group without vitamin A and group 2 was supplemented with vitamin A. The data on estrus intensity, number of follicles and pregnancy rate obtained were processed using the Chi-square analysis of 2x2 contingency tables. If the Chi-square test does not meet the requirements, the formula used is the Fisher exact test. While the data on the diameter of the follicles were analyzed by ANOVA test. The results of the research data showed that supplementation of vitamin A had a significant difference (P&lt;0.05) on the intensity of estrous. Meanwhile, the results of the chi-square test on the number of follicles and pregnancy rates (P&gt;0.05) showed that there was no significant difference. Likewise, the ANOVA test on follicle diameter between control cows and vitamin A treated cows did not have a significant difference. Although in this study it did not affect the number of follicles, follicle diameter and pregnancy rate. However, it has an economic effect of 20% on the pregnancy rate in the livestock industry scale.

The effect of progesterone concentrations during superovulation of Holstein heifers in a randomized trial

The aim of this study was to evaluate the effect of different progesterone (P4) concentrations during the follicular growth on the intensity of estrous expression, ovarian response to the superovulatory treatment, and embryo production and quality in superovulated heifers. A total of 63 Holstein heifers were randomly assigned into 2 experimental groups: Low P4 (n = 31) and High P4 (n = 32). Animals received a pre-synchronization protocol followed by a protocol of superovulation that included the allocated P4 treatment. Activity was monitored continuously by an automated activity monitor, and estrus characteristics (maximum intensity and duration) were recorded. Embryo collection was performed 7 d post artificial insemination (AI). Embryos were counted and graded from good or excellent (1) to degenerated (4). The outcomes of interest were: number and diameter of follicles at the time of AI, ovulation success (confirmed 7 d post-AI), time to estrus event, maximum intensity and duration of estrus, number and quality of embryos. Data were analyzed according to the type of outcome variable using logistic, linear, or Poisson regression models. A total of 105 embryos (High P4: n = 42; Low P4: n = 63) were graded for quality. Different P4 levels did not affect the maximum intensity (High P4 = 497.8 ± 23.9%; Low P4 = 542.2 ± 23.5%) or the duration (High P4 = 13.5 ± 1.5 h; Low P4 = 14.3 ± 1.4 h) of estrus. Heifers in the High P4 treatment had greater number of follicles at time of AI (High P4 = 16.6 ± 1.6 follicles; Low P4 = 13.9 ± 1.2 follicles), but with smaller diameter (High P4 = 11.3 ± 0.1 mm; Low P4 = 12.0 ± 0.1 mm) compared with Low P4. High P4 heifers tended to have better embryo quality compared with Low P4 heifers (odds ratio = 1.98; 95% CI = 0.90-4.35). High P4 heifers had less embryos than Low P4 heifers, but this was modified by the CIDR (intravaginal implant of P4) removal to estrus interval (interval 0-21 h: mean ratio = 1.15, 95% CI = 0.42-1.87; interval 22-46 h: mean ratio = 0.58, 95% CI = 0.27-0.96). Although estrous expression was not associated with embryo quality, as the duration and the maximum intensity of estrous expression increased, the number of embryos recovered 7 d post-AI increased (duration: mean ratio = 1.04; 95% CI = 1.03-1.05; maximum intensity: mean ratio = 1.50; 95% CI = 1.42-1.58). In conclusion, P4 during the follicular growth, and intensity of estrus, are playing a role in regulating the quality and the number of embryos produced by superovulated heifers. This study was supported by contributions from Resilient Dairy Genome Project and the Natural Sciences and Engineering Research Council.

A randomized study on the effect of an extended voluntary waiting period in primiparous dairy cows on fertility, health, and culling during first and second lactation

When the voluntary waiting period (VWP), defined as the days between calving and when the cow is eligible to receive the first insemination, is extended, high-yielding dairy cows may have better opportunities to regain energy balance before first insemination. This study investigated the effect of an extended (145-215 days in milk [DIM], n = 280) or conventional (25-95 DIM, n = 251) VWP treatment on fertility, disease incidence, and culling rate in cows during their first lactation. The cows were also followed through a second lactation without intervention regarding VWP, during which the farmers could decide when they wished to start the inseminations. This was done in a randomized-controlled study on 16 high-yielding commercial herds in southern Sweden, containing a total of 531 primiparous cows of the Holstein and Red Dairy Cattle breeds. Data from the Swedish national dairy herd recording scheme collected between August 2018 and September 2021 were used in the analysis, including records on breed, calvings, estrus intensity, inseminations, disease, somatic cell count, culling date, and culling reason. During first lactation, more cows receiving the extended VWP treatment showed strong estrus intensity (score 4-5, 55% vs. 48%) and fewer showed moderate estrus intensity (score 3, 35% vs. 43%) at first insemination, compared with cows receiving the conventional VWP treatment. First service conception rate (FSCR) was higher (67% vs. 51%) and number of inseminations per conception (NINS) was lower (1.6 vs. 2.0) during the first lactation for cows receiving the extended compared with the conventional VWP treatment. For disease incidence rate or culling rate expressed as number of events per cow-time in the study, we found no differences between the cows receiving the 2 VWP treatments in any lactation. Calving to first service interval during second lactation was longer (86 vs. 74 d) for cows with extended compared with conventional VWP. In conclusion, primiparous cows with extended VWP showed improved reproductive functions, in the form of higher estrus intensity, greater FSCR, and lower NINS, during the first lactation. However, we observed no apparent effect on these fertility measures during the following lactation (without VWP intervention) and no differences in disease prevalence or culling between cows receiving the 2 different VWP treatments in either lactation. Compliance with the planned VWP treatment was lower for cows with planned extended compared with planned conventional VWP treatment. We studied the "intention-to-treat" effect (i.e., the results for all cows randomized to each treatment regardless of whether the planned VWP was achieved or not) to identify any bias arising due to degree of compliance. However, we found no difference in culling rate between cows randomized to an extended VWP compared with those randomized to a conventional VWP. These findings can be used to support management decisions on VWP length in high-yielding dairy herds.

Intensity of estrus expression – valuable obvious determinant of fertility in Bos indicus cows

This study aimed to characterize estrus response and to establish relationships between intensity of estrus, preovulatory follicle (POF) size and estradiol (E2) concentrations on day of AI, luteal profiles and pregnancy outcome in lactating Hariana breed of cows. 200 cyclic cows were subjected to Ovsynch (n = 54) and Pre-OV treatment (n = 146). Ovsynch: Buserelin acetate (BA; 10 µg), Cloprostenol (500 µg) and BA (10 µg) were injected i.m. on day 0, 7 and 9, respectively, irrespective of treatment. Pre-OV: BA (10 µg) and Cloprostenol (500 µg) was also injected i.m. simultaneously 7 days prior to initiate Ovsynch. On the basis of estrus behavior, the cows were classified into three groups: weak, moderate and intense. Artificial insemination performed at 18–24 hours after 2nd BA of Ovsynch in both treatments. The average duration of estrus did not differ (p > 0.05) between Ovsynch and Pre-OV treatment. A positive correlation was observed between estrus response and POF size, concentration of E2 on day of AI and luteal profiles on day 12 post-AI. First service conception rate was higher in cows exhibited intense (45.46%) and moderate (42.56%) estrus response than weak (28.57%) estrus response. In conclusion, intensity of estrus expression could be considered as important determinant for deciding pregnancy outcomes in Bos indicus cows.

152 The effect of high or low concentration of progesterone during diestrus and its association with intensity of oestrus in lactating Holstein cattle

152 The effect of high or low concentration of progesterone during diestrus and its association with intensity of oestrus in lactating Holstein cattle

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).

Relationship of Gonadotropin-Releasing Hormones (GnRH) Induction to Reproductive Performance in Batur Sheep

Experiments were performed to determine the relationship of Gonadotropin-Releasing Hormone (GnRH) induction to estrus activity and pregnancy rate of Batur sheep. Twenty Batur sheep were synchronized to estrus using intramuscularly injection of 2 ml PGF2α that repeated in 11-day intervals. GnRH was given intramuscularly on the 9th day for 10 Batur sheep, and 10 others were not injected as a control. Reproductive performance included estrus intensity, estrus onset, mating time period, and pregnancy rate. The data were analyzed by regression correlation tests, and chi-square test were used for pregnancy rate. The statistical analysis results showed that the induction of GnRH has a very significant relationship (P&lt;0.01) to the intensity and onset of estrus as well as the time-mating period it has a significant relationship (P&lt;0.05). The pregnancy rate was significantly different (P&lt;0.05) between control and GnRH-induced in Batur sheep. The results showed that GnRH induction contributed to the intensity of estrus, the onset of estrus, and the time-mating period of 37.88, 42.79, and 22.16%, respectively. The pregnancy rate in Batur sheep induced by GnRH compared to controls has 25.0% increased. It can conclude that GnRH induction was able to improve reproductive performance in Batur sheep