Insemination Data Research Articles

Genetic parameters for body weight from birth to calving and associations between weights with test-day, health, and female fertility traits

A data set including 57,868 records for calf birth weight (CABW) and 9,462 records for weight at first insemination (IBW) were used for the estimation of direct and maternal genetic effects in Holstein Friesian dairy cattle. Furthermore, CABW and IBW were correlated with test-day production records and health traits in first-lactation cows, and with nonreturn rates in heifers. Health traits considered overall disease categories from the International Committee for Animal Recording diagnosis key, including the general disease status, diarrhea, respiratory diseases, mastitis, claw disorders, female fertility disorders, and metabolic disorders. For single-trait measurements of CABW and IBW, animal models with maternal genetic effects were applied. The direct heritability was 0.47 for CABW and 0.20 for IBW, and the direct genetic correlation between CABW and IBW was 0.31. A moderate maternal heritability (0.19) was identified for CABW, but the maternal genetic effect was close to zero for IBW. The correlation between direct and maternal genetic effects was antagonistic for CABW (-0.39) and for IBW (-0.24). In bivariate animal models, only weak genetic and phenotypic correlations were identified between CABW and IBW with either test-day production or health traits in early lactation. Apart from metabolic disorders, there was a general tendency for increasing disease susceptibilities with increasing CABW. The genetic correlation between IBW and nonreturn rates in heifers after 56 d and after 90 d was slightly positive (0.18), but close to zero when correlating nonreturn rates with CABW. For the longitudinal BW structure from birth to the age of 24 mo, random regression models with the time-dependent covariate "age in months" were applied. Evaluation criteria (Bayesian information criterion and residual variances) suggested Legendre polynomials of order 3 to modeling the longitudinal body weight (BW) structure. Direct heritabilities around birth and insemination dates were slightly larger than estimates for CABW and IBW from the single-trait models, but maternal heritabilities were exactly the same from both models. Genetic correlations between BW were close to 1 for neighboring age classes, but decreased with increasing time spans. The genetic correlation between BW at d 0 (birth date) and at 24 mo was even negative (-0.20). Random regression model estimates confirmed the antagonistic relationship between direct and maternal genetic effects, especially during calfhood. This study based on a large data set in dairy cattle confirmed genetic parameters and (co)variance components for BW as identified in beef cattle populations. However, BW records from an early stage of life were inappropriate early predictors for dairy cow health and productivity.

Climate zone influences the effect of temperature on the day of artificial insemination on fertility in two Iberian sheep breeds

To determine whether climate, based on the Koppen Climate Classification, influences the effect of temperature on the day of artificial insemination (AI) on fertility in sheep, 1,931 AI performed on Spanish farms of the Rasa Aragonesa (RA) and Churra (CH) breeds were studied. Farms were categorized as Koppen BSk (Farm BSk-RA; n=229), and Koppen Cfb (Cfb-RA; n=372), Koppen Csb (Csb-CH; n=908), and Koppen Cfb (Cfb-CH; n=422). Mean, maximum, and minimum temperatures (°C) were recorded, and thermal amplitude (maximum-minimum temperatures) calculated. Each set of temperature data was distributed between percentile-groups (≤50% and >50%), below or above the median. Temperatures at AI were significantly (P 50 percentile groups indicated that inseminations performed when temperatures were within the >50 percentile had a significantly (P 1 for one or more of the meteorological variables under study; meanwhile, in the other two climates, OR were 0.05). In conclusion, the effects of temperature on fertility after AI differed depending on the climate zone in which the flocks were reared. The results have implications for the scheduling of insemination dates to achieve the maximal performances.

A longitudinal cohort study of acute puerperal metritis cases in Swedish dairy cows.

BackgroundAcute puerperal metritis affects cows during the early postpartum period and causes fever, fetid vaginal discharge and general depression. The disease is severe and treatment with antimicrobials is often required. This study followed 79 Swedish dairy cows with acute puerperal metritis with registered treatment and outcome in terms of recovery. Bacteria isolated from the uterus and their susceptibility to penicillin were studied. Clinical cases were assigned by participating practitioners who examined the cows, performed uterine swab sampling, decided treatment and provided information about cow health and calving conditions. Fertility and culling data were collected from the official Swedish milk and health recording scheme. Recovery from disease was defined in four levels; as a cow that survived 1 or 4 months, was inseminated and subsequently became pregnant. Intervals from dates of first and latest calving to insemination date were studied.ResultsThe most common bacterial findings were a mixed culture of Escherichia coli and bacteria such as Gram positive cocci, Fusobacterium necrophorum, Clostridium spp. or Trueperella pyogenes. The Gram positive cocci, Pasteurella spp. and F. necrophorum were generally susceptible to penicillin. The majority of cows (70%) were treated with penicillin in accordance with the Swedish policy on treatment of metritis while 19% were treated with tetracycline and 8% were not treated with antimicrobials. Recovery rates were similar between treatments. Besides “calving to last insemination” interval (CLI) that was 5 days shorter than the national mean, fertility was slightly reduced compared to national means. “Calving to first insemination” interval (CFI) was 4 days longer than national mean and number of inseminations/cow increased from 1.9 to 2.1. Escherichia coli culture positive cows did not become pregnant to the same extent as cows without E. coli in the uterus (P = 0.046). Twin births resulted in a longer CFI (P = 0.034). The culling rate was generally high (42% within 300 days after occurrence of metritis), though death associated with acute disease was low (6%).Conclusions Escherichia coli was the most common bacterial pathogen isolated from cases of acute puerperal metritis in the present study. This bacterium is inherently resistant to penicillin, but although most cows were treated with penicillin, death due to acute disease was low and recovery and final fertility results were acceptable. In times of emerging antimicrobial resistance and demand for prudent antimicrobial use, we suggest that penicillin is a “good enough” choice if antimicrobial treatment of acute puerperal metritis is needed.Electronic supplementary materialThe online version of this article (doi:10.1186/s13028-016-0257-9) contains supplementary material, which is available to authorized users.

Analysis of non-return rate in Italian Holstein Friesian bulls

Until recently non-return rate 56 days (NR56) for Italian Holstein Friesian bulls had been published only for artificial-insemination (AI) organizations. Since December 2015, the information about sire fertility has been published also for the farmers. The objectives of this research were to assess the importance of information about the cow’s age at insemination and editing of age of bulls for improving prediction of bull fertility. The intent was to revise the old model, even if NR56 is a phenotypic assessment of bull’s prospective fertility and not a genetic evaluation. Factors considered for the revision of the model were date of insemination, age of cows at the time of mating and number of matings. Data included 3,726,450 records from 3,210 bulls and 1,312,901 cows in 7,395 herds from January 2011 till January 2016. Results revealed that alternative models ignoring AI organization and using only last five years of insemination, multiple services and editing on age of bull improved accuracy of predictions.

КОМП’ЮТЕРНА СИСТЕМА ДЛЯ ОБЛІКУ МОЛОЧНОЇ ПРОДУКТИВНОСТІ ТА КОНТРОЛЮ ЛАКТАЦІЙНО–ВІДТВОРЮВАЛЬНОГО ЦИКЛУ КОРІВ

Ефективність молочного скотарства передбачає високу продуктивність корів, яка залежить від їх генетичного потенціалу, від забезпеченості кормами та від створення на фермах і комплексах відповідних умов утримання. Основним завданням селекції в молочному скотарстві є підвищення продуктивності корів. Тому раціональне ведення молочного скотарства передбачає знання закономірностей зв’язку показників молочної продуктивності із показниками відтворювальної здатності корів. З метою вивчення особливостей зв’язку вказаних показників пропонується комп’ютерна інформаційна система, яка дозволяє реалізувати їх системний облік та подальший аналіз. Система розроблена засобами MS ACCESS і містить базу даних, що складається із сукупність реляційних таблиць, в яких міститься загальна (умовно постійна) інформація про тваринницьке підприємство, про обслуговуючий персонал, про тварин стада. Основною (оперативною) є інформація про молочну продуктивність тварин протягом усіх років лактації та інформація про основні репродуктивні дані корів стада, а саме: дата осіменіння, дата отелу, ознака тільності, величина сервіс–періоду. Запропонована комп’ютерна інформаційна система дозволяє разом з обліком та наступним аналізом молочної продуктивності стада корів також забезпечувати інформаційний супровід організації та контролю їх лактаційно–відтворювального циклу.

Short communication: Effect of heat stress on nonreturn rate of Italian Holstein cows

The data set consisted of 1,016,856 inseminations of 191,012 first, second, and third parity Holstein cows from 484 farms. Data were collected from year 2001 through 2007 and included meteorological data from 35 weather stations. Nonreturn rate at 56 d after first insemination (NR56) was considered. A logit model was used to estimate the effect of temperature-humidity index (THI) on reproduction across parities. Then, least squares means were used to detect the THI breakpoints using a 2-phase linear regression procedure. Finally, a multiple-trait threshold model was used to estimate variance components for NR56 in first and second parity cows. A dummy regression variable (t) was used to estimate NR56 decline due to heat stress. The NR56, both for first and second parity cows, was significantly (unfavorable) affected by THI from 4 d before 5 d after the insemination date. Additive genetic variances for NR56 increased from first to second parity both for general and heat stress effect. Genetic correlations between general and heat stress effects were −0.31 for first parity and −0.45 for second parity cows.

Factors associated with the differential in actual gestational age and gestational age predicted from transrectal ultrasonography in pregnant dairy cows

The objective of the study was to determine (1) how gestational age predicted using transrectal ultrasonography related to actual gestational age derived as the number of days from the most recent artificial insemination date, (2) what factors, if any, were associated with the differential between the two measures, and (3) the association between this differential in gestational age and the likelihood of subsequent pregnancy loss, stillbirth, or calving dystocia. The data set contained 7340 ultrasound records from 6805 Holstein Friesian dairy cows in 175 herds. Ultrasonography assessment underestimated gestational age relative to days since last service by 0.51 days (standard error [SE]: 0.040), although the differential was less during embryonic development phase (i.e., ≤42 days of gestation; mean overestimation of 0.31 days) versus fetal development phase (i.e., >42 days of gestation; mean underestimation of 0.81 days). Predicted calving date calculated from ultrasonography was 1.41 days (SE: 0.040) later than the actual subsequent calving date and was, on average, 0.52 days later than predicted calving date, assuming a gestation length of 282 days. Parity of the dam (P < 0.05), stage of pregnancy (P < 0.001), and sex of the calf born (P < 0.001) were all associated with the differential in gestational age based on ultrasonography versus days since last service. No obvious trend among parities was evident in the difference between the methods in predicting gestational age. Ultrasonography underestimated gestational age by 0.83 (SE: 0.15) days in parity 5+ cows and underestimated gestational age by 0.41 (SE: 0.14) days in the first-parity cows. Relative to gestational age predicted from the most recent service, ultrasonography underestimated gestational age by 0.75 (SE: 0.13) days for heifer fetuses and underestimated gestational age by 0.36 (SE: 0.13) days for bull fetuses. The heritability of the differential in gestational age between the methods of prediction was low 0.05 (SE: 0.022), corroborating heritability estimates for most cow reproductive traits. Overestimation of gestational age using ultrasonography was associated with an increased likelihood of pregnancy loss (P < 0.001). Gender of calf born (P < 0.001), sire breed of calf (P < 0.001), and parity (P < 0.001) were all associated with gestation length. Gestation length was 1.27 days longer (SE: 0.01) for bull calves compared to heifer calves. Calves from beef sires had a longer gestation length than calves from dairy sires, and older parity cows had a longer gestation length than younger cows. The results highlight factors associated with differences in gestational age obtained from ultrasonography and insemination data and illustrate the value of ultrasonography for the prediction of calving date and pregnancy loss.

Estrus traits derived from activity measurements are heritable and closely related to the time from calving to first insemination

The aim of this study was to estimate genetic parameters for estrus-related traits that could improve selection for increased fertility due to improved ability of the cow to return to cycling and go into heat after calving. We compared the time from calving to first insemination (CFI) to 3 physical activity traits: the interval from calving to first high activity (CFHA), estrus duration (ED), and estrus strength (ES). We calculated CFI based on data from commercial Holstein herds that included the insemination dates for 11,363 cows. The CFHA, ED, and ES traits were derived from electronic activity tags for 3,533 Holstein cows. Estimates of heritability were 0.07 for CFI, 0.16 for CFHA, 0.02 for ED, and 0.05 for ES. We found a strong genetic correlation between CFI and CFHA (0.96). Genetic correlations between ED and CFI and CFHA were −0.37 and −0.68, respectively. Genetic correlations between ES and CFI and CFHA were −0.50 and −0.58, respectively. The heritability of CFHA and its strong genetic correlation with CFI suggest that including CFHA in the genetic evaluation of female cow fertility could improve the effectiveness of selection, because CFHA reflects the ability to return to cyclicity and go into heat after calving.

Effect of heat stress on pregnancy rates of crossbred dairy cattle in Terai region of Uttarakhand, India

Abstract Objective To test whether heat stress during one or both of the critical periods (pre-insemination and post-insemination) causes reduction in pregnancy rates of crossbred dairy cattle in Terai region of Uttarakhand. Methods Data on metereological (ambient temperature and humidity) and reproductive (date of artificial insemination and day 60 reproductive status) variables were collected for a total of 1199 inseminations and allocated, on the basis of temperature humidity indices during 30 days before and after insemination, to one of the four groups: Thermoneutral-thermoneutral (TN-TN), Thermoneutral-heat stress (TN-HS), Heat stress-thermoneutral (HS-TN), and heat stress-heat stress (HS-HS). Results Chi -square analysis of the day 60 pregnancy data revealed lower ( P Conclusions These results indicate that reduction in pregnancy rates of crossbred dairy cattle due to heat stress in the Terai region was evident only when both growth of the ovulatory follicle and fertilization and early embryonic development occurred in the heat stress period. In addition, the study showed that use of temperature humidity indices rather than the traditional seasonal classification could provide more accurate insights into the effects of heat stress on pregnancy rates of crossbred dairy cattle in the Terai region.

Trivers–Willard hypothesis revisited: Does heat stress peri–insemination alter secondary sex ratio in crossbred dairy cattle?

To test the hypothesis that heat stress peri–insemination skews towards female the secondary sex ratio in dairy cattle. In addition, the effect of heat stress peri–insemination on birth weight of resultant calves was investigated. Data on the date of insemination and sex and birth weight of the resultant calf were collected for a total of 934 single births on a crossbred dairy farm and grouped into thermoneutral and heat stress peri–insemination groups on the basis of temperature humidity indices on the day of insemination. Logistic regression revealed no difference in the secondary sex ratios between thermoneutral (53.4:46.6) and heat stress (52.5:47.5) peri–insemination groups. These sex ratios were not different from the expected 50:50 ratio on Chi–square goodness of fit test. Differences in birth weight of calves between thermoneutral and heat stress peri–insemination groups did not approach statistical significance. These results indicate that heat stress peri–insemination does not affect secondary sex ratio and calf birth weight in crossbred dairy cattle.

Test accuracy of metabolic indicators in predicting decreased fertility in dairy cows

Negative energy balance is a known risk factor for decreased fertility in dairy cows. This study evaluated the accuracy of plasma concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and insulin-like growth factor 1 (IGF-1)—factors related to negative energy balance—in predicting decreased fertility. One plasma sample per cow was collected from 480 cows in 12 herds during the period from d 4 to 21 in milk and analyzed for NEFA, BHBA, and IGF-1. For each cow, data on breed, parity, calving date, gynecological examinations, and insemination dates were obtained. Milk samples from 241 cows in 7 of the participating herds were analyzed for progesterone concentration to define the first day of luteal activity. The diagnostic sensitivity (Se) and specificity (Sp) at different cut-off concentrations of NEFA, BHBA, or IGF-1 were calculated and related to individual cow fertility status, measured as anestrus (ANEST), delayed first artificial insemination (DFAI), or delayed conception. Positive and negative predictive values (PV+; PV−) were calculated considering different levels of (within-herd) prevalence. Strata (i.e., subgroup)-specific Se and Sp and associations between test results and fertility parameters were investigated using logistic regression. The NEFA and BHBA tests for ANEST and DFAI had the highest combined Se and Sp and were thus evaluated further. Cut-off values with Sp around 80% were used in this step to provide a reasonable number of test-positive cows, representing a practical situation. This corresponded to a cut-off value for the NEFA test of 400 µEq/L (Se 0.27–0.45) and for the BHBA test of 1.8mM (Se 0.15–0.30) across all cows included in the study. The estimated Sp was generally higher than the original 80%, but the corresponding Se was further decreased when the test was used in heifers compared with older cows. The true prevalence of ANEST in the study population was 27%, which gave a PV+ of 0.36 to 0.45 and a PV− of 0.76 to 0.79. With 35% true prevalence of DFAI, PV+ was 0.29 to 0.38 and PV− was 0.64 to 0.66. Thus, overall test performance was low when metabolic indicators measured as single values in early lactation were used to predict fertility in dairy cows, but accuracy was influenced by cow-level factors such as parity. The prevalence of the target condition (in this case, decreased fertility) also influences test usefulness and should be considered when planning test systems and interpreting test results.

Transabdominal ultrasonography in standing position for pregnancy diagnosis in Awassi ewes

The study was conducted to use the transabdominal ultrasonography in standing position for pregnancy diagnosis in Awassi ewes. Four groups of ewes were included, the first group included 35 ewes examined after 90–100 days of insemination, the second group included 14 ewes examined after 70–80 days of insemination, the third group included 78 ewes have different date of insemination (45–120 days), the fourth group included 15 ewes examined at five different times; 21–24, 28–32, 40–43, 47–50 and 57–60 days after insemination. The ewes were examined transabdominally in standing position by applying of 3.5MHz sectorial probe at the hairless area of the inguinal region of right sides without shaving of the ventral abdominal wall. At lamping the accuracy of ultrasonographic examinations was 100% for ewes of the first three groups, the diagnosis of pregnancy was very fast (about 0.5min) by observation of fluid filled uterus and placentomes, but observation of fetuses and their parts required more time (about 1min). The accuracy of pregnancy diagnosis in ewes of fourth group which done at 21–24, 28–32, 40–43, 47–50 and 57–60 days after insemination were 53% (8/15), 80% (12/15), 100% (15/15), 100% (15/15) and 100% (15/15), respectively. In conclusion, transabdominal ultrasonography in standing position is fast, safe and reliable for pregnancy diagnosis in Awassi ewes, and 100% of accuracy can be got after 40 days of insemination.

Effect of Supplemental Feeding with Glycerol or Propylene Glycol in Early Lactation on the Fertility of Swedish Dairy Cows

The aim of this field study was to evaluate the effect of supplemental feeding with glycerol (GLY) or propylene glycol (PG) during early lactation on the fertility of Swedish dairy cows. Within 17 commercial dairy herds, 798 cows were randomized to three groups that were daily fed supplements with 450 g GLY, 300 g PG or nothing (control, C). The supplements were given twice daily during 0-21 days in milk as a top dress on concentrates. Data on calving date, insemination dates, gynaecological examinations, as well as breed, parity and monthly milk yield were collected. From a subset of 308 cows in seven herds, milk samples for progesterone analysis were taken twice weekly and used to determine the time for onset of luteal activity. The effects of supplements on the intervals from calving to first luteal activity (FLA), first AI (FAI) and conception (CON), respectively, were analysed using semi-parametric survival models (Cox proportional hazards models) controlling for the effect of parity, breed, calving season, milk yield and the clustering effect of herd. There was no difference in time to FLA between the cows in group C and in group GLY or PG. No differences in time to FAI or in time to CON were found between cows in group PG and group C. However, cows in the GLY group tended to get their FAI later compared with cows in the control group but without at subsequent delaying of time to CON.

Relationships between Body Weight and Milk Yield During the Early Postpartum Period and Bull and Technician and the Reproductive Performance of High Producing Dairy Cows

The aim of this study was to evaluate the effect of body weight (BW) change during the early postpartum period and BW on day 50 post partum on the subsequent expression of estrus and fertility at first insemination before day 90 post partum. The data were derived from 1036 postpartum cows reaching 90 days in milk. The following data were recorded for each animal: lactation number, daily milk production at day 50 post partum, calving date, days in milk at estrus and at AI, insemination date, insemination number, inseminating bull, AI technician and body weight at calving, at day 50 post partum and at AI. Of the 1036 cows registered, 817 (78.9%) showed first estrus before day 90 post partum and were inseminated. Using logistic regression procedures and based on the odds ratio a one unit (kg) increase in the daily milk production at day 50 post partum and a one unit (kg) decrease in the BW between calving and day 50 post partum were related to a 1.03-fold increase and a 0.97-fold decrease in the estrus expression rate before day 90 post partum, respectively. Of the 817 cows inseminated before day 90 post partum, 437 became pregnant (53.5%). A one unit increase in the BW at day 50 post partum produced a 1.003-fold increase in the early fertility rate. Pregnancy rate before day 90 was also influenced by the season at calving, bull providing semen and technician. In conclusion, the register of BW during the postpartum period may be a useful tool for evaluating the nutritional status and its relationship with the subsequent reproductive efficiency in dairy cows.

Reinsemination intervals after timed artificial insemination or estrus-detected inseminations (2012)

The objective was to quantify the reinsemination intervals of lactating dairy cows that were either inseminated at estrus or received a timed AI (TAI) at first service. Cows in Experiment 1 were enrolled in a TAI program before first AI after calving. Cows detected in estrus after 50 days in milk (DIM) were inseminated, whereas the remainder continued in the TAI program and were inseminated as scheduled. Cows in Experiment 2 also were enrolled in a TAI program and were inseminated accordingly at first service after calving. On day 7 after TAI, cows were assigned randomly to receive either saline (control) or 1,000 IU human chorionic gonadotropin (hCG) to induce accessory luteal structures (corpora lutea) in an attempt to improve pregnancy outcome. First-repeat insemination dates were recorded for all cows after the initial AI and grouped as 25 days since first AI. More cows in Experiment 1 that were inseminated at estrus returned to estrus before 25 days than TAI cows and during summer months had shorter average return intervals by 1.7 days. More cows in Experiment 2 that received saline and had no accessory luteal structures also returned to estrus before 25 days than cows receiving hCG. Equal proportions of saline and hCG-treated cows (25%) in Experiment 2 had retained at least one of their original luteal structures until day 28 after TAI, but were not pregnant at day 32. Of those nonpregnant cows that retained luteal structures, average concentrations of pregnancy-specific protein B (BioPRYN test) concentrations were slightly elevated, but failed to retain the embryos to day 32 after AI. Furthermore, progesterone concentrations of these cows that lost their embryos were compromised compared with pregnant cows by day 21 after AI. Regardless of the number of luteal structures after first insemination, 25% were retained up to 28 days after AI, indicating pregnancy had occurred but embryo loss occurred between pregnancy recognition (day 15) and days 28 to 32 after insemination. Cows receiving TAI also had longer reinsemination intervals than cows inseminated at estrus, a phenomenon that is exaggerated during summer heat stress.

Cow Effects and Estimation of Success of First and Following Inseminations in Dutch Dairy Cows

The objective of this research was to determine the contribution of cow factors to the probability of successful insemination accounting for the serial number of inseminations in analysis. The investigation was performed with 101,297 insemination records in 51,525 lactations of different cows from 1368 herds obtained from the Dutch milk production recording database. Cows that had a first insemination (AI) between 40 and 150 days post-partum with one or more inseminations (≤6 inseminations) were selected. An insemination was defined successful when not followed by another insemination and when the cow calved between 267 and 295 days after insemination, or when the cow was culled between 135 and 295 days after the last insemination. Breed, parity, days in milk, lactation curve characteristics, milk production traits, moment of AI related to peak milk yield time (before or after peak milk yield), the last calf (female, male, twin or stillbirth) and season of insemination were selected as independent parameters for a model with successful rate of insemination as dependent parameter. A multivariable logistic regression model was used within cow and farm as a random effect. The probability of successful insemination was the highest in the first insemination and decreased in the following inseminations. However, the success rate of all inseminations increased in a later stage of lactation. The improvement in the successful inseminations in a later stage of lactation was better in multiparous cows than in first parity cows. Insemination in summer and before peak milk yield time reduced the success of insemination. The success rate was the lowest in 100% Holstein Friesian cows compared with other breeds and was the highest when the last calf was a female calf compared to a male calf, twin or stillbirth. In conclusion, the success of first and following inseminations depended on parity, breed, season of insemination, last calf status, daily milk yield at insemination date, serial insemination number and days in milk at insemination date.

Bovine herpesvirus type 4 (BHV-4) infection in relation to fertility in repeat breeder dairy cows

In this study, blood serum was collected from 162 repeat breeder (RB) dairy cows and tested by enzyme linked immunosorbent assay (ELISA). Of these samples, 87 were bovine herpesvirus type-4 (BHV-4) seropositive and 75 were BHV-4 seronegative. The prevalence of BHV-4 was determined as 53.70% amongst RB dairy cows. In the current study the seroprevalence was high. The average days open (DO) of pregnant BHV-4 seropositive RB cows was significantly longer (p<0.01) than that of pregnant BHV-4 seronegative RB cows, but was not significant for age of animals (p=0.186) or conception rate (CR) (p=0.14). The averages calving to the fourth insemination date (CFIDI) and age of nonpregnant BHV-4 seropositive RB cows was significantly higher (p< 0.05) than non-pregnant BHV-4 seronegative RB cows. In conclusion, a close fertility negative relationship existed between BHV-4 infections and fertility in RB dairy cows.

Estimation of genetic parameters for 13 female fertility indices in Holstein dairy cows

This study was aimed to assess genetic parameters for 13 traits in heifers and first-parity Holstein dairy cows. Data consisted of calving and insemination dates of 14,707 Holstein dairy cows in Isfahan province of Iran. Reproductive traits included age at first service (AFS), first service to conception (FSTC), gestation length (GL), age at first calving (AFC), calving to first service (CTFS), days open (DO), calving interval (CI), number of services per conception (NS), and non-return rate at 56 days (NRR). Model equations were optimized using GLM procedure in SAS package following genetic analysis using animal models in ASREML software. Minimum and maximum departure from normal distribution for phenotypic records belonged to AFS, NRR, GL, DO, CI and AFC, NS, FSTC, CTFS, respectively. Estimated heritability varied from 0.002 (NRR) to 0.184 (GL) in heifers and from 0.003 (NRR) to 0.153 (GL) in first-parity cows. AFS, CTFS, and GL were noticeably heritable compared to other assessed traits. Estimated absolute additive genetic correlations were in the range of 0.01 (NRR and AFS) and 0.99 (NRR and NS) in heifers and 0.07 (GL and CI) to 1 (FSTC and CI) in cows. Additive genetic correlations were antagonistic between AFS and other traits, except AFC. Interestingly, NRR which has been included in sire catalogs had the highest average absolute genetic associations with other traits.

Evaluation of bull fertility in dairy and beef cattle using cow field data

A successful outcome to a given service is a combination of both male and female fertility. Despite this, most national evaluations for fertility are generally confined to female fertility with evaluations for male fertility commonly undertaken by individual breeding organisations and generally not made public. The objective of this study was to define a pertinent male fertility trait for seasonal calving production systems, and to develop a multiple regression mixed model that may be used to evaluate male fertility at a national level. The data included in the study after editing consisted of 361,412 artificial inseminations from 206,683 cow-lactations (134,911 cows) in 2,843 commercial dairy and beef herds. Fixed effects associated with whether a successful pregnancy ensued (pregnant = 1) or not (pregnant = 0) from a given service were year by month of service, day of the week, days since calving, cow parity, level of calving difficulty experienced, whether or not the previous calving was associated with perinatal mortality, and age of the service bull at the date of insemination. Non-additive genetic effects such as heterosis and recombination loss as well as inbreeding level of the service bull, dam or mating were not associated with a successful pregnancy; there was no difference in pregnancy rate between fresh or frozen semen. Random effects included in the model were the additive genetic effect of the cow, as well as a within lactation and across lactation permanent environmental effect of the cow; pedigree group effects based on cow breed were also included via the relationship matrix. Temporal differences in the AI technician and service bull were also included as random effects. A difference in five percentage units in male fertility was evident between the average effects of different dairy and beef breeds. The correlation between raw pregnancy rates for bulls with more than 100 services (n = 431) and service bull solutions from the mixed model analysis was 0.66. The correlation between the raw pregnancy rates of 288 technicians with more than 100 services and their respective solutions from the mixed model was 0.35. These low to moderate correlations suggest considerable re-ranking among both service bulls and technicians and suggest possibly a benefit of using a statistical model to better estimate the performance of both service bulls and technicians.

Heterologous in vitro fertilization is a good procedure to assess the fertility of thawed ram spermatozoa

A heterologous in vitro fertilization (IVF) test using calf oocytes with zona pellucida was employed to assess the fertility of thawed ram sperm samples. Six males with significant differences in fertility ( P = 0.003) were used. The males were classified as having high fertility (≥42%) and low fertility (≤41%). Male fertility was not influenced by number of inseminated ewes ( P = 0.584), insemination technician ( P = 0.156), insemination date ( P = 0.323) or farm ( P = 0.207). Thawed sperm samples were employed to assess several sperm parameters for each male: motility, acrosomal integrity, viability, membrane stability, membrane phospholipid disorder, mitochondrial membrane potential and chromatin stability. These samples were used to carry out a heterologous in vitro fertilization. In vitro-matured calf oocytes ( n = 716) were inseminated with thawed ram semen and in vitro cultured for 40 h. Overall, at thawing, variability among males respect to sperm quality was high. Despite this variability, there were not differences ( P < 0.05) between fertility groups. Yield of hybrid embryos ranged from 31 to 59% between males. There were not differences between males ( P = 0.340). However, there were differences between fertility groups (high fertility: 55%; low fertility: 39%; P = 0.020). Multiple regression analysis showed that the heterologous in vitro fertility was the only predictive parameter for in vivo male fertility. Correlation between both parameters was fair ( r 2 = 0.760; P = 0.025). These results indicate that heterologous in vitro fertilization tests can be useful to predict the fertility of ram spermatozoa using calf oocytes with intact-zona pellucida.