Risk factors limiting first service conception rate in dairy cows and their economic impact

This study was conducted to evaluate the association between ovarian structures, uterine characteristics and physical attributes of cervico-vaginal mucus (CVM) with conception rate in normal cyclic dairy cows (N=20) at estrus. Different physical parameters of CVM at estrus such as quantity, consistency, color, pH, Spinnbarkeit value and fern pattern were evaluated. Transrectal ultrasonography was done at estrus to carry out the morphometry of follicles and uterine horns as well as following artificial insemination, the mid-cyclic corpus luteum size and functionality were assessed on the 10th day using B-mode and color Doppler ultrasonography. Among the physical parameters, significantly higher (p<0.05) Spinnbarkeit values were recorded for subsequently pregnant (n=12) as compared to non-pregnant cows (n=8). The mean diameter of the preovulatory follicle at estrus and corpus luteum vascularity (%) was significantly higher (p<0.05) in subsequently pregnant as compared to non-pregnant cows while, no significant difference (p>0.05) was recorded for intraluminal uterine fluid diameter and endometrium thickness. In conclusion, higher spinnbarkeit and preovulatory follicle diameter at estrus led to a better conception rate in dairy cows.

Effects of administration of gonadotropin-releasing hormone at artificial insemination on conception rates in dairy cows

The aim of this study was to identify the effect of ambient temperature and season of the year on conception difficulties in Holstein cattle. The experiment was conducted on the School farm in Žabčice. Data were collected from July 2016 to January 2017. Experimental population counted 263 breeding Holstein cows, which were inseminated during the observation period. Results of this study confirmed the effect of temperature and season on conception rates in dairy cows. In winter season, successful conception was recorded in 56.36 % of cows in average ambient temperature 1.48 °C, in summer season the conception rate was only 40.43 % in average daily temperature 18.96 °C. A more detailed analysis revealed the highest conception rates in the dairy cows in January (88.24 %) and February (91.67 %). On the contrary, the worst results were recorded in September (22.73 %) and October (28.57 %). Evaluation of conception rate according to ambient temperature intervals showed best results for the temperatures below 5 °C. A part of the study was also evaluation of an association between daily milk yield and conception rate. This hypothesis cannot be conclusively confirmed, because milk yield was mostly similar in both groups (pregnant and non‑pregnant) on the days of insemination. The effect of lactation order and mean daily milk yield on the conception rate in cows was not confirmed.

Effect of a single growth hormone (rbST) treatment at breeding on conception rates and pregnancy retention in dairy and beef cattle

The associations between occurrence of diseases, milk yield, and body condition score on conception risk after first artificial insemination were analysed in an observational study of 43 farms participating in a herd health program. Data were taken from 9369 lactations, from 4382 cows inseminated between 20 and 180 days in milk in the period 1990 to 1996. Two logistic regression models, one containing data from all lactations and a subset containing data from 1762 lactations with body condition scoring were used to determine pregnancy risk at first AI. A 1-point loss in body condition score during the 100 days after calving resulted in a 20 percent reduction in the risk of conception. Relative within herd kg milk yield had a significant and linear negative association with fertility. Increases and decreases in the percentage milk fat (or milk fat to protein ratios) from the monthly test days near to AI date are significantly (P < 0.01) predictive of AI outcome. Metritis, cystic ovarian disease, lameness, and mastitis gave odds ratios of for pregnancy risk ranging from 0.35 to 1.15, largely dependent on the interval in days from final disease occurrence to first AI. The advantages of coding diseases for linear or non-linear time-dependency were examined. Other diseases with significant effects associations to pregnancy risk were displaced abomasum, milk fever and retained foetal membranes. These diseases showed little relationship between fertility and the number of days since last occurrence. Results of this study confirm the negative effects of milk yield, body score condition loss, and disease on dairy cow fertility. The effects of some diseases on first service conception are strongly dependent on the interval since last disease occurrence. This is especially valid for clinical mastitis which has an extremely weak effect on conception if occurring prior to AI and is associated with > 50 percent reduction in pregnancy risk if occurring in the 3 wk period directly after AI.

Conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone and/or prostaglandin F2 alpha

The study aimed to determine the effectiveness of single and double-shot estrus synchronization protocols on conception and estrus response rates in dairy cows. Among 195 sampled female animals, only 174 cows and heifers met a standard of the protocols. Animals were prepared for hormone injections based on their breed, parity number, and body condition score (BCS). Among 174 sampled animals, 120 were indigenous and the rest 54 were crossbreds, and 143 cows and 31 heifers were selected for single alfagladin C (Cloprostenol) injections. Whereas, 16 of them were given double alfagladin C (Cloprostenol) injections when they did not showed estrus prior to single injection. All data was collected and analyzed by SPSS version 20 software. Through observation, inspection and rectal palpation, 90.8% of 174 synchronized animals showed estrus response with a single dose, whereas 16 of them (100%) showed estrus response with double injections. Overall, 48.3% of cows and heifers became pregnant. The conception rate of cows/heifers varied significantly through each protocol, with 50% of animals conceived by double injection treatment and 48.1% of cows conceived through single shot treatment. Additionally, there was a substantial difference in estrus response across breeds, BCS, and parity number. Furthermore, the rates of conception in local and crossbred cows were 40.8 and 64.8%, respectively. In terms of body condition, a high conception rate (58.6%) was observed in the good body condition score. The conception rate and estrus response were significantly different in parity number. In general, the double protocol outperform than the single protocol in terms of estrus and conception rate. Accordingly, stakeholders or artificial insemination technicians might apply double protocols after a single injection to obtain remarkable results. Nevertheless, strict follow-up is required, and more resources at the farmer's management level are required.

The effect of interval from day of administration of bovine somatotropin (bST) to synchronization of ovulation and timed-insemination on conception rate of dairy cows with and without ovarian cysts

The aim of the present study was to evaluate the effect of various administration routes of PGF2α analogue, D-cloprostenol, at the time of artificial insemination (AI) on conception rate in a large dairy herd. A total number of 659 lactating dairy cows (101 heifers and 558 cows) were enrolled in the study. Following heat detection, the cows were artificially inseminated according to the AM-PM rule. The animals were divided into a control (29 heifers and178 cows) and three experimental groups; IM (53 heifers and 110 cows), IV (155 cows) and IU (19 heifers and115 cows) groups that received intramuscular 150 µg, intravenous 150 µg and intrauterine 5 µg of D-cloprostenol, respectively, at the time of AI. The control group did not receive any treatment at the time of AI. To measure serum progesterone concentration, blood samples were obtained from 15 cows in each group at the time of insemination and on days 4 and 15 post-insemination. Pregnancy was diagnosed by rectal ultrasound examination between days 35-40 post-insemination. The effects of treatments, parity, milk production, and days in milk (DIM) on conception rate of adult cows were evaluated using the multivariate logistic regression model. Intramuscular administration of D-cloprostenol at the time of AI significantly increased conception rate in dairy cows compared to the control group (60.1% vs. 40.6%; p = .005). However, intravenous and intrauterine administration of D-cloprostenol did not alter the conception rate (32.3%; p = .29 and 50%; p = .11, respectively). D-cloprostenol treatment at AI could not significantly increase the conception rate of heifers followingboth (IM & IU) administration routes. In conclusion, this study showed that intramuscular administration of D-cloprostenol at the time of insemination might improve the conception rate in adult cows, while its intravenous and intrauterine administration did not induce any positive effects on reproductive efficiency of dairy cows. HIGHLIGHTS Intramuscular administration of D-cloprostenol at the time of insemination might improve the conception rate in adult cows. Intravenous administration of D-cloprostenol did not induce any positive effects on reproductive efficiency of dairy cows. Intrauterine administration of D-cloprostenol did not induce any positive effects on conception rate of dairy cows.

The objective of this study was to determine the effects of various amounts of plasma progesterone (P4) throughout an ovsynch treatment protocol on conception rate in dairy cows.

Controlled internal drug release (CIDR) devices for releasing progesterone have been used for reproductive management in dairy cattle. In order to minimize the cost, the devices can be reused upon disinfection after being used for 7-8 days. Therefore, the aim of this research is to compare the conception rate of dairy cows after the first, second, and third-use of CIDR devices timed following artificial insemination (TAI) protocol. A total of 783 cows receiving short-term hormonal protocol (9.5 days) by inserting CIDR for 7 day. At the initiation of the TAI protocol, cows were randomly assigned into three groups, (1st CIDR; n = 312), (2nd CIDR; n = 233), and (3rd CIDR; n = 238). Moreover, in each CIDR group, cows were subdivided into two types (primiparous and multiparous cows). Cows in all groups were inseminated on day 9.5 of the TAI protocol. Diagnosis of pregnancy was performed using ultrasound on days 30 and 60 after insemination. From the results, the 1st, 2nd and 3rd used CIDR devices did not significantly change the conception rates on days 30 (28.8% vs. 25.3% vs. 28.2%, respectively) and 60 (26.9% vs. 24.5% vs. 27.7%, respectively) post-TAI in dairy cows (P > 0.05). The embryonic loss did not differ among cows receiving the 1st, 2nd and 3rd used CIDR devices (6.7% vs. 3.4% vs. 1.5%, respectively) (P > 0.05). For each CIDR group, parity (primiparous and multiparous) did not alter conception rates on days 30 and 60 post-TAI and embryonic loss in dairy cows (P > 0.05). Our findings indicate that the CIDR device could be used for at least three times in the TAI protocol in primiparous and multiparous dairy cows.

The successful outcome of an insemination is a combination of both male and female fertility-linked factors. We investigated the first service conception rate of cows at artificial insemination (AI) in the smallholder dairy farms in Bangladesh. Frozen straws were prepared from ejaculates of Bos indicus (n=7) and Bos indicus×Bos taurus (n=7) AI bulls. Fertility was determined from 6101 first services in cows that were performed by 18 technicians in four regions between April 2004 and March 2005. Pregnancy was diagnosed by rectal palpation between 60 and 90days post-insemination. The Asian version of Artificial Insemination Database Application (AIDA ASIA) was used for bulls-, cows- and AI-related data recording, and later retrieved for analysis. The mean±SD number of inseminations performed from individual bulls and their conception rates were 436.0±21.6 and 50.7±1.9%, respectively. Logistic regression demonstrated body condition scores (BCS), heat detection signs, months of AI and their interactions had greatest effects (odds ratios: 1.24-16.65, p<0.04-0.001) on first service conception rate in cows. Fertility differed (p<0.02-0.001) between the regions, previous calving months, months of AI, BCS, parity and heat detection signs of cows. Inseminations based on mounting activity (n=2352), genital discharge (n=3263) and restlessness and/or other signs (n=486) yielded a conception rate of 53.6%, 48.8% and 50.1%, respectively (p<0.05). Conception rate between technicians ranged between 43.4% and 58.6% (p<0.05). The days interval from calving to first service (overall mean±SD=153.4±80.6) had relationship (p<0.001) with BCS, months of previous calving and parity of the cows. Fertility at AI in smallholder farms can be improved by training farmers on nutrition and reproductive management of the cows.

Aim This study was conducted using the questionnaire method to assess the effect of breed and factors affecting conception rate on artificial insemination in dairy cows in Tullo district, Western Haraghe, Ethiopia. Methods A follow-up study design was conducted from December 2018 to June 2019 to determine the effect of breed and factors affecting conception rate to artificial insemination in dairy cows, taking breed, age, parity, body condition and timing of insemination as risk factors. The demographic factors were recorded by interviewing the owners. Most of the cows were examined for pregnancy diagnosis by rectal palpation of the genital tract at 60-80-days post-artificial insemination. Results Out of 114 artificially inseminated cows/heifers, 59 became pregnant, giving an overall first service conception rate of 51.8%. Although the breed, age, parity and body condition score did not affect the conception rate significantly, the pregnancy rate was better in the cross-breed (62.5%), in cows of 5-7-years of age (54.6%), in cows of parity 2-3 (59.2%) and in cows of good body condition score (57.7%). The conception rate in cows inseminated at 12-18-hours after the onset of estrus was significantly higher (62.3%) than those inseminated after 18-hours (31.2%) and before 12-hours (52.4%) after the onset of estrus. Therefore, cows with good body condition score (BCS) and artificial insemination (AI) service at 12-18-hours after the onset of estrus are the best choice of selection for obtaining the best result in the first service conception rate to AI in dairy cows/heifers. Conclusion This study reveals that the conception rate was influenced by the time of AI, so awareness should be given to cattle owners, as they should give AI for their cattle at optimum time within 12-18-hours after onset of heat sign.

In recent years, reproductive performance of dairy cows has been declining worldwide, especially among cows of high genetic merit for milk production. The cause of the low fertility may considerably vary across countries and is probably multifactorial. This problem remains unsolved. Further, the first-service conception rate of dairy cows has remarkably decreased worldwide. The number of services required for conception has increased due to the low fertility in dairy cows. However, there are few reports about the relationship between conception rates and the number of services in the current dairy cows. The objective of this study was to investigate whether the number of services affects the conception rates of dairy cows. Data concerning the conception rates was obtained for 8386 Holstein cows from 40 commercial dairy herds in eastern Hokkaido, Japan, from 2006 to 2009. The diagnosis of pregnancy was confirmed by rectal palpation between 30 and 45 days after insemination. The average interval between calving and the first-service was 87.3 days. The average milk yield was 8500 kg. Number of conducting services was from the first to the seventh service. The conception rate was analysed using chi-square test. The results are presented in Table1. The conception rate from the first to the seventh service was 40.2 to 54.0%. The conception rate at the first service was significantly low (40.2%); however, the conception rates did not significantly differ after the second-service. A similar tendency was observed during each year. Moreover, the total percentage of conceptions from the first to the third service was 83.8%. The average number of services per conception was 2.2. The results of this study indicate that the first service yielded the lowest conception rates. The conception rates after the second service did not significantly differ. Moreover, ∼84% of the dairy cows became pregnant between the first service and the third service. However, this result shows that ∼16% of the dairy cows in the herds were repeat breeding. In order to improve fertility, it is necessary to study the factors that affect the first-service conception rates of dairy cows. Moreover, to improve the conception rate of dairy cows, it is important to elucidate the cause of these problems. Table 1.The number and percentage of dairy cows conceiving at each of the services for consecutive services

The current study was designed to investigate the therapeutic effectiveness of Allium sativum (garlic) extract infusion on recovery and conception rate in cows with subclinical endometritis. Cows (42) with subclinical endometritis were randomly divided into 2 equal groups. In treatment group (group T), cows received a single intrauterine administration of 10 ml garlic extract mixed with 40 ml saline. In the cows of control group (group C), no intrauterine treatment was administered. Samples were collected again from the all animals of both groups on day 14 after therapy and the same laboratory tests were repeated. The cows were artificially inseminated at the following estrus. 10 (23.8 %) out of 42 cows had subclinical endometritis without bacteria in the uterus; however majority of cows with subclinical endometritis were positive for bacterial infection (76.2%). Bacterial load in group T was significantly lower as compared to both pre-treatment and group C. The cure rate for group T and C was 100.0 and 19.0%, respectively. The conception rates in groups T and C were 52.4 and 14.3%, respectively. Our results indicated that the intrauterine use of garlic extract can decrease endometrial inflammation and bacterial load, and consequently an increase in the conception rate.