Conception Rate In Dairy Cows Research Articles

Review on performance responses of dairy cattle against thermal stress

This manuscript is aimed at reviewing the performance responses of dairy cattle against thermal stress resulting from climate change. Climate change is the major factor that largely affects the dairy industry. Thermal stress (TS) is the perceived discomfort and physiological strains associated with exposure to excessive ambient temperature. Temperature and Humidity Index (THI) have been adopted to describe thermal conditions that drive thermal stress in dairy cattle. The effects of TS are devastating in the dairy industry if not managed well. The thermo-neutral zone for dairy cattle and calves in the tropics is THI <72. Milk yield reductions of up to 50% have been reported for Holstein cows due to thermal stress under summer climate conditions. Moreover, thermal stress is associated with alterations in milk composition. TS reduces the length and intensity of estrus manifestation. Moreover, 80% of estrus may be unnoticeable during the summer season in temperate regions, which further reduces fertility. Conception rates of dairy cows may drop up to 20–27% in the summer season. Climate-induced thermal stress resulted in a decrease of 3.5 kg and 25 kg in the birth weight and weaning weight of Fogera calves, respectively. Dry matter feed intake was reduced by 9.6%. Commonly used thermal stress reduction strategies included modification of the physical environment, breeding for heat-tolerant dairy cattle, and nutritional management. The productive and reproductive traits are susceptible to the negative impacts of thermal stress with an increase in THI above 68.0 for Holstein Frisian cattle and their crosses and 72 for tropical cattle under an open shed system. Mitigations of thermal stress by breeding heat-tolerant animals, using a loose house system, and season-based feeding should be considered an integral component of the dairy cattle management system.

Association of Ovarian Structures, Uterine Characteristics and Cervico-vaginal Mucus Attributes with Conception in Dairy Cows

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.

Efficiency evaluation of two estrus synchronization protocols in estrus response and conception rate of dairy cows in the Dalocha district, Ethiopia

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.

Effect of Different Thawing Methods for Frozen Bull Semen and Additional Factors on the Conception Rate of Dairy Cows in Artificial Insemination.

Simple SummaryToday, recommendations for thawing methods for frozen bull semen vary, and clear data to assess their influence on fertility are contradictory. Under present practical conditions, no differences between the three different thawing methods could be detected, so no clear recommendation for semen thawing methods in dairy reproduction can be made based on our data. Study results provide evidence that inadequate reproductive performance of high-producing, lactating dairy cows is a multifactorial consequence of farm and fertility management; accordingly, the livestock industry should focus more on cow health to avoid reproductive disorders and further improve the reproductive performance of dairy cows in the future.Recommendations for thawing methods of frozen bovine semen vary and clear data evaluating their influence on fertility are contradictory. In this respect, the aim of this study was to investigate the influence of different thawing methods of frozen bull semen in artificial insemination (AI) of dairy cows on conception rate (CR) under practical conditions and to determine further possible influencing factors on the success of AI in order to provide recommendations for practical use. From 2017 to 2019, 3393 AI were performed in a dairy farm in eastern Germany, distributed randomly into three groups of thawing methods: group A: n = 426 (11 s, 38 °C water bath); group B: n = 348 (35 s, 38 °C water bath); group C: n = 385 (30 s, “in the cow”). We observed no significant difference in CR from the general linear mixed model between the thawing methods (method A/B/C, 28.5%/26.6%/24.7%), but data analysis revealed effects of lactation number, month of insemination and AI method (natural heat vs. OvSynch) on CR. Based on our data, no clear recommendation for semen thawing method in dairy reproduction can be made. Our findings suggest that the main factors of influencing reproductive performance in the field are represented by the cow-side of fertility, e.g., insemination in natural heat, lactation number and season of insemination. Therefore, dairy farmers should focus more on cow conditions to further improve reproductive performance.

Dietary organic trace mineral supplement affects steroid hormone, antioxidant enzyme concentrations, and reproductive performances in dairy cows

Supplementation of organic trace mineral (OTM) may affect reproductive functions in several aspects and has been studied, but very rare is reported in dairy cows. To determine the effects of dietary OTM supplement during pre- and postpartum with timed artificial insemination (TAI) protocol on steroid hormones, antioxidant enzymes, and reproductive performances in dairy cows. Prepartum Holstein cows (n = 60) were randomly assigned to received either a control diet or OTM supplemented for 42 days. Both groups were fed the same total mixed ration, but were supplemented with 5 g/head/d OTM (Bioplex®) in the treatment group. Blood and follicular fluid samples were collected to determine progesterone (P4), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and estradiol (E2) concentrations. Cows fed OTM had better placental expulsion period, milk yield, and reproductive performance parameters (day to first ovulation and estrus, percentage of first estrus and size of preovulatory follicle) than control cows (P < 0.05). Cows fed OTM affected (P < 0.05) the serum concentration of P4 on days 12, 15, 18, 21, and 42 after TAI. Follicular fluid concentrations of E2 in large follicle in OTM cows were greater than control cows (336.3 and 376.9 ng/mL; P < 0.05). Cows supplemented with OTM had greater serum SOD and GSH-Px activities than control cows (15.5 vs. 10.6 U/mL and 12.1 vs. 9.9 U/mL; P < 0.05). In conclusion, supplements with OTM improved uterine and placental health, steroid hormones concentrations, and antioxidant enzyme activities but did not improve conception rate in dairy cows.

Factors affecting calving to conception interval (days open) in dairy cows located at Dessie and Kombolcha towns, Ethiopia.

This study was aimed at determining the median days of calving to conception interval (days open) and identifying the major risk factors determining the days open in dairy cows. Both retrospective and longitudinal studies were conducted on dairy cows located in the Dessie and Kombolcha towns of South Wollo Zone, northeast Ethiopia from August 2019 to August 2020. The Kaplan-Meier model of survival analysis was used to determine the median days open and compare the survival distribution of each level of explanatory variables likely to influence the days open of dairy cows. Accordingly, the overall conception rate of dairy cows was 44.7%. The median days open in the study was 154 days. There is a 16% probability of surviving (i.e, the probability that the conception event has not yet occurred) at the end of 210 days postpartum period. The Cox proportional hazard model was used to quantify the effect of each of the explanatory variables on the days open in the first 210 days postpartum. Factors that had a significant effect (p<0.05) on the calving to conception interval were the season of insemination, breeding system, calving to insemination interval, and herd milk yield level. However, the peripartum, postpartum disorders, and the town of the farm are not significant (p>0.05). Accordingly, cows inseminated in the autumn season (HR = 4.45), cows less than or equal to 85 days calving to insemination interval (HR = 2.41), artificially inseminated cows (HR = 1.45), and high herd milk yield cow had a higher probability of becoming pregnant. In conclusion, the management practices and breeding decisions seem to be important determinants to improve the conception rate or decrease the days open in dairy cows.

Improvement of First-Service Conception Rate in Dairy Cows after the Injection of Pregnant Mare Serum Gonadotropin Six Days Postpartum

BACKGROUND: Early resumption of ovarian activity after parturition could positively influence the fertility of dairy cows. Ovulation of the first postpartum follicular wave and formation of corpus luteum that secretes progesterone can sub-stantially benefit the resumption of ovarian cyclicity in cows. In this regard, the presence of a dominant follicle in the ovary before day 10 postpartum could enhance ovulation rate in the first postpartum follicular wave. Pregnant mare serum gon-adotropin (PMSG) is one of the hormones with the potential to improve the growth of follicles. OBJECTIVES: Accordingly, the present study was conducted to evaluate the effect of PMSG injection six days after parturition on reproductive parameters in dairy cows. METHODS: The subjects were randomly assigned to the two groups of control (N=74) and treatment (N=79). Cows in the control group received no treatment, while animals in the treatment group received 500 IU PMSG on day six postpartum. In both experimental groups, cows were subjected to Presynch-Ovsynch protocol 30-35 days postpartum. The subjects that experienced estrus during the Presynch-Ovsynch protocol were inseminated. On the other hand, the cows that were not in estrus during this period were subjected to fixed-time insemination at the end of the Presynch-Ovsynch protocol. Pregnancy was diagnosed 45 days after artificial insemination using the rectal examination. RESULTS: In the control group, 66.22% of cows were inseminated based on estrus detection and 33.78% of cows were inseminated at fixed times. In the intervention group, 68.35% of cows were inseminated based on estrus detection and 31.65% of cows were inseminated at fixed times. The first-service conception rate (FSCR) was 27.03% and 48.1% in the control and treatment groups, respectively (p =0.01). CONCLUSIONS: The present study showed that the injection of 500 IU PMSG six days after parturition could enhance FSCR in dairy cows.

The effect of various administration routs of D-cloprostenol at the time of artificial insemination on conception rate in dairy cattle

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.

Characterization of intrauterine cultivable aerobic microbiota at the time of insemination in dairy cows with and without mild endometritis

It is generally accepted that postpartum uterine infections decrease conception rates in dairy cows. Whereas clinical endometritis (CE) has been studied intensively, only little information about CE at the time of artificial insemination (AI) is available. The aim of this study was to characterize the intrauterine cultivable aerobic microbiota in healthy cows and in cows with mild CE at AI and to investigate its effect on the subsequent insemination success. The vaginal discharge score (VDS) of 120 Holstein Frisian dairy cows was assessed shortly after AI using the Metricheck device and pregnancy diagnosis was performed 39 days after AI. On average, cows received their second insemination (2.0 ± 1.2 standard deviation (SD)) and were 120.5 ± 40.2 days in milk. Intrauterine cytobrush samples were taken from cows with clear mucus (VDS 0, n = 58) and from cows with flecks of pus (VDS 1, n = 62), which was regarded as mild CE. Bacteria collected with the cytobrush were cultivated aerobically and identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 358 bacterial isolates were recovered, comprising 49 bacterial genera and 116 species. Bacillus, Staphylococcus, Corynebacterium and Streptococcus were the most prevalent genera with relative abundances of 19.6%, 14.2%, 10.1% and 8.1%, whereas common uterine pathogens, such as Trueperella pyogenes and Escherichia coli, were rarely detected. Bacillus spp. were more frequently detected in group VDS 0 (51.7%) than in VDS 1 (22.6%; P = 0.001) and there was a higher prevalence of Corynebacterium spp. in VDS 0 than in VDS 1 (37.9% vs 19.3%; P = 0.03). Cows with VDS 1 at the time of AI harbored neither Bacillus licheniformis nor Bacillus subtilis, while these species were detected in 27.6% and 8.6% of VDS 0 (P < 0.001 and P = 0.024 respectively). The insemination success in VDS 0 and 1 was 43.1 and 25.8% (P = 0.046). The diagnosis of mild CE at AI and the total bacterial load decreased the chance of pregnancy (P = 0.03) but no significant correlation between a distinctive bacterial species and insemination success was observed. In summary, cultivable uterine bacteria at AI presumably represent a part of the physiological microbiota, which is not directly linked to impaired fertility. These findings question intrauterine antimicrobial treatment shortly after AI and could represent the basis for the development of future treatment strategies.

Effect of Removal of Follicular Cyst Content on Success of Ovsynch in Dairy Cows

The purpose of this study was to evaluate the effect of removing cyst content on conception rate in dairy cows treated for follicular cysts with Ovsynch. The trial was conducted using data collected over regular herd health visits in a private practice.

Fucosyltransferase gene expression in goat endometrium during the estrous cycle and early pregnancy

Regulation of the expression of the alpha(1,2)fucosyltransferase (FUT) genes and their enzymatic products, including the H-type 1 antigen (HT1), on the luminal surface of the uterus is believed to be critical for establishment of pregnancy in mammals. The FUT1 gene is a marker for conception rates in dairy cows and HT1 is a marker for uterine receptivity in rodents. To determine the spatiotemporal expression patterns of FUT1 and FUT2 genes in goats, endometrial tissues were obtained on six days spanning the estrous cycle (Days 5, 11, 13, 15, 17 and 19) and seven days spanning early pregnancy (Days 5, 11, 13, 15, 17, 19 and 25). In all data, we found no effect of status (cyclic or pregnant; P > 0.1) and pooled data where appropriate. We cloned FUT1 cDNA from goat endometrium and made probes from it for Northern and slot blot analyses. The analyses indicated that FUT1 gene expression was high until Day 13, and then declined. In situ hybridization revealed a change in the cell-specificity of FUT1 gene expression over the estrous cycle and early pregnancy. In situ hybridization signal intensity scores indicated that FUT1 expression by uterine epithelium was high on Day 5, moderate on Day 11, and minimal on subsequent days. In situ hybridization signals in uterine glandular epithelial cells remained high from Day 5 to Day 13, with weaker signals thereafter. Quantitative reverse transcription-PCR (RT-qPCR) assays were used for quantitation of FUT1 and FUT2 mRNAs. Quantitative RT-qPCR data were generated from endometrium collected from cyclic and pregnant animals on Days 5, 11 and 17. Relative levels of FUT1 mRNA were high on Days 5 and 11, but then fell 5-fold by Day 17 (P < 0.01). FUT2 mRNA concentrations were below the accurate detectable limit of the assay. High levels of HT1 were observed on the apical surface of uterine luminal epithelia on Days 5, 15, 17 and 19, with much lower levels on Days 11 and 13. Thus, data suggests that FUT1 is the primary enzyme responsible for the high levels of HT1 antigen present on the uterine luminal epithelium between Days 5 and 11 of the estrous cycle and early pregnancy. But changes in the expression of the FUT1 gene does not directly correlate to HT1 staining, which increased from Day 13–15. Future studies are required to understand the regulation of the HT1 antigen on the luminal surface of endometrium.

Corpus luteum development and angiogenesis

Summary. Development of the corpus luteum (CL) is vital for the early increase in postovulatory progesterone that drives embryo development and the successful establishment of pregnancy. Following ovulation, rapid and dramatic cellular reorganisation and intense angiogenesis are required to support the timely transition to progesterone secretion. In addition to inherent physiological challenges, this process is sensitive to any imbalance in metabolism or health, particularly in the modern high yielding dairy cow. This makes luteal inadequacy a common cause of poor early embryo development and low conception rates in dairy cows. This review will explore the potential mechanisms that underlie this disorder. It will describe the impact that the pre-ovulatory follicle infrastructure, gonadotrophin support and size of the LH surge have on subsequent luteal development and function. A crucial component for rapid luteal growth is the formation of new blood vessels or angiogenesis. Several recent studies have highlighted the critical importance of fibroblast growth factor 2 (FGF2) in regulating this process. In particular, FGF2 has a profound influence on endothelial cell sprouting and branching. There is increasing evidence that pericytes, immune cells and platelets are also integral regulators of luteal angiogenesis and development. The complex and dynamic nature of luteal development means that it is likely to be sensitive to potential inadequacies particularly, in the high producing dairy cow.

Factors Affecting Conception Rate of Dairy Cows Following Artificial Insemination in Selected Area at Sirajgonj District of Bangladesh

Factors Affecting Conception Rate of Dairy Cows Following Artificial Insemination in Selected Area at Sirajgonj District of Bangladesh

Insulin effect during a Heatsynch protocol in dairy cows

ABSTRACT: The objective of this study was to evaluate the effect of exogenous insulin administration on follicular growth, estrus presentation and conception rate during a protocol of ovulation synchronization. Dairy cows were subjected to the Heatsynch protocol, with the insertion of an intravaginal device containing 1.9 g of progesterone (CIDR) and an intramuscular injection containing 2.5 mg of GnRH on day 0. On day 7, the CIDR was removed and subjects were given 12.5 mg of dinoprost. Also on day 7, Insulin Group (IG, n = 21) animals received a subcutaneous injection containing 0.25 IU / kg of recombinant human insulin and the control group (CG, n = 25) received a 0.9% NaCl injection. On day 8, an injection of 0.5 mg of estradiol cypionate was administered to all cows. Animals were inseminated 12 hours after estrus presentation or at day 10 at fixed time. Follicular development was evaluated on days 7, 9, and 10 using transrectal ultrasonography, estrus presentation was observed between days 8 and 10, and conception rate was evaluated 30 days after AI. There were no differences in growth rate, follicular diameter, estrus presentation, and conception rate. Therefore, application of a single dose of insulin does not promoted an increase in follicular size, estrus presentation and conception rate in dairy cows.

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

ObjectiveWe determined the risk factors limiting first service conception (FSC) rate in dairy cows and their economic impact.MethodsData were collected from 790 lactations regarding cow parity, peri- and postpartum disorders, body condition score (BCS), reproductive performance, and expenses associated with reproductive management (treatment, culling, and others). Initially, we identified the risk factors limiting FSC rate in dairy cows. Various biological and environmental factors, such as herd, cow parity, BCS at 1 month postpartum and first artificial insemination (AI), resumption of cyclicity within 1 month of calving, year, AI season, insemination at detected estrus or timed AI, peri- and postpartum disorders, and calving to first AI interval, were evaluated. Next, we evaluated the economic impact of the success or failure of FSC by comparing the expense associated with reproductive management until conception between cows that did or did not conceive at their first service.ResultsCows with BCS <3.0 had a lower probability of conceiving at first insemination (odds ratio [OR] = 0.64, p<0.05) than cows with BCS ≥3.0. Cows inseminated during summer were less likely to conceive (OR = 0.44, p<0.001) than cows inseminated during spring. Cows with peri- or postpartum disorders were less likely to conceive (OR = 0.55, p<0.001) than cows without disorders. Survival curves generated using MedCalc showed an 81 day extension in the mean interval between calving and conception in cows that failed to conceive over those that did conceive at first insemination. Cows failing conceive required additional expenditure on reproductive treatment ($55.40) and other management ($567.00) than cows that conceived at first insemination.ConclusionLower BCS, hot weather at first insemination, and peri- and postpartum disorders are risk factors limiting FSC, which result in an economic loss of $622.40 per dairy cow.

Effects of the Bull on Conception Rate of Dairy Cows in Different Seasons and According to AI Type

Background: Reproductive efficiency is one of the most important factors affecting the performance dairy cattle, and fixedtime artificial insemination (TAI) is an important biotechnology factor employed in bovine livestock. The achievement of satisfactory results in TAI protocols depends of several factors, such as health and body condition, milk yield, environmental temperatures, ovulation time, semen manipulation, as well as semen quality. The goal of this study was to evaluate the conception rate of heifers and multiparous cows based on different Holstein bulls used for artificial insemination (AI). The effects of the type of management AI, animal category, and season of the year were also examined.Materials, Methods &amp; Results: A three-year database on the reproductive management of a dairy farm was formed. All the cows and heifers were of the Holstein breed, in semi-intensive nutritional management, milked twice a day, and received a total mix ration. After 45 days in milk, when cows were observed twice daily with estrus signs, posterior artificial insemination occurred 12 h after estrus visualization was made. However, cows that were not observed in estrus were submitted to a timed artificial insemination (TAI). In this study, these fixed factors were considered: bulls utilized for the AI (totalizing 10 animals with at least 100 inseminations in each season, denoted by the letter B and a number - B1, B2, B3, B4, B5, B6, B7, B8, B9, B10); the season of the insemination (spring/summer being from November to April and autumn/winter from May to October), category animal (heifers, animals that never have been calved, or multiparous, animals that have already given birth more than once), and the type of AI (which included TAI using a protocol for synchronization, but cows having not necessarily shown estrus signs at the AI; ETAI: using protocol of synchronization, cows showing estrus signs at the AI; and AI with estrus visualization, without protocol of synchronization when animals were observed in estrus and were inseminated 12 h later. The fertility parameter of the bulls and reproductive performance in AI was based on conception rate. There was a statistical difference among different bulls in the same season (P ≤ 0.05). There was also a difference in reproductive performance of the same bulls between seasons, autumn/winter and spring/summer; B8 37.8% vs. 32.0% (P = 0.05) and B10 35.1% vs. 20.7% (P = 0.003). Regarding the individual animal category, only one bull (B6) demonstrated higher reproductive performance when utilized in the AI of heifers than multiparous 39.2% vs. 27.2% (P = 0.01). Similarly, regarding the effect of the type of AI, only one bull (B8) exhibited different results, obtaining better results for conception rate when utilized in fixed TAI with estrus visualization (35.5%) and in the AI with estrus visualization (39.0%) compared with that of TAI (19.9%) (P &lt; 0.05).Discussion: From these results, it was observed that some bulls exhibited better performance in situations of greater challenge. In addition, some animals presented variation in efficiency with the demonstration of estrus or not. Therefore, bulls that present semen with higher fertility in certain types of AI could be utilized on a larger scale for to increase the reproductive rates in artificial insemination. The results of this study indicate that despite the tests indicating the semen that is submitted is adequate, there are still variations in quality and the reproductive efficiency of each bull. With the effects varying based on fertility and on different environmental and management situations.

Addition of meloxicam to the treatment of bovine clinical mastitis results in a net economic benefit to the dairy farmer

Recently, it has been shown that the addition of meloxicam to standard antimicrobial therapy for clinical mastitis (CM) improves the conception rate of dairy cows contracting CM in the first 120 d in milk. The objective of our study was to assess whether this improved reproduction through additional treatment with meloxicam would result in a positive net economic benefit for the farmer. We developed a stochastic bio-economic simulation model, in which a dairy cow with CM in the first 120 d in milk was simulated. Two scenarios were simulated in which CM cases were treated with meloxicam in conjunction with antimicrobial therapy or with antimicrobial therapy alone. The scenarios differed for conception rates (31% with meloxicam or 21% without meloxicam) and for the cost of CM treatment. Sensitivity analyses were undertaken for the biological and economic components of the model to assess the effects of a wide range of inputs on inferences about the cost effectiveness of meloxicam treatment. Model results showed an average net economic benefit of €42 per CM case per year in favor of the meloxicam scenario. Cows in the no-meloxicam treatment scenario had higher returns on milk production, lower costs upon calving, and reduced costs of treatment. However, these did not outweigh the savings associated with lower feed intake, reduced number of inseminations, and the reduced culling rate. The net economic benefit favoring meloxicam therapy was a consequence of the better reproductive performance in the meloxicam scenario in which cows had a shorter calving to conception interval (132 vs. 143 d), a shorter intercalving interval (405 vs. 416 d), and fewer inseminations per conception (2.9 vs. 3.7) compared with cows in the no-meloxicam treatment scenario. This resulted in a shorter lactation, hence a lower lactational milk production (8,441 vs. 8,517 kg per lactation) with lower feeding costs in the meloxicam group. A lower culling rate (12 vs. 25%) resulted in lower replacement costs in the meloxicam treatment scenario. All of the scenarios evaluated in the sensitivity analyses favored meloxicam treatment over no meloxicam. This study demonstrated that improvements in conception rate achieved by the use of meloxicam, as additional therapy for mild to moderate CM in the first 120 d in milk, have positive economic benefits. This inference remained true over a wide range of technical and economic inputs, demonstrating that use of meloxicam is likely to be cost effective across many production systems.

The Effect of Ambient Temperature on Conception and Milk Performance in Breeding Holstein 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.

Cattle Review

Introduction: This edition of Cattle Review considers papers on routine foot trimming in heifers, genetic resistance to bovine tuberculosis (bTB) and the effects of post-insemination progesterone supplementation on conception rates in dairy cows.

Effect of intrauterine Allium sativum extract on recovery and conception rate in dairy cows with subclinical endometritis

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.