Sex ratio after insemination of bovine spermatozoa isolated using a bovine serum albumin gradient

This experiment was undertaken to determine if a method reported to successfully enrich the proportion of Y-chromosome-bearing spermatozoa in human semen could be adapted for separation of bovine spermatozoa. Semen was collected from four Angus bulls and aliquots were either separated on discontinuous gradients of bovine serum albumin (BSA) or untreated before processing for cryopreservation. Two hundred seventy-one cows or heifers were assigned randomly to be artificially inseminated (20 X 10(6) sperm/insemination) with separated or unseparated spermatozoa. The proportions of male offspring were 45 and 54% after inseminations with separated or unseparated spermatozoa, respectively. In a second phase of the experiment, pooled semen from three Holstein bulls was either extended and frozen without separation or frozen after separation using the discontinuous BSA gradient. Separated and unseparated spermatozoa were analyzed by flow cytometry to determine the ratio of X- and Y-chromosome-bearing spermatozoa based on differences in DNA content. The ratios of X- and Y-bearing spermatozoa in separated or unseparated samples were indistinguishable. We concluded that the separation method did not enrich the proportion of Y-bearing bovine spermatozoa.     

Accuracy of pregnancy diagnosis in swine by ultrasonography

Early and accurate diagnosis of nonpregnant sows and gilts has the potential to increase reproductive efficiency and the financial income in pig production by reducing non-productive days per sow per year. The objectives of this study were to compare the efficiency of pregnancy diagnosis between Doppler Echo+ and real time ultrasonography (RTU) and to compare the efficiency by using RTU at different days post-mating (days 17 to 24) under commercial conditions. In the 1st study, using crossbreed sows and gilts (n=107), pregnancy diagnoses were done with Doppler Echo+ and then with RTU. Between 28 and 65 days of gestation, Doppler Echo+ had 85% sensitivity and 32% specificity, and efficiency was 73%. In the 2nd study, sows (n=142) were scanned for pregnancy diagnosis between 17 and 24 d post-mating (PD1) and reconfirmed between 38 and 45 days of gestation (PD2). After 21 days of gestation, RTU had over 90% sensitivity and 45% specificity, and 70% efficiency. Accuracy between PD1-farrowing was 75.5% and between PD1 and PD2 was 80.6%. In the 3rd study, sows were diagnosed pregnant by RTU (n=151) at 17 to 24 days of gestation or A-mode ultrasound (n=172) at 28 to 30 days of gestation. There were no significant differences in conception rate (P > 0.09) and farrowing rate (P > 0.67) between both groups. Hence, there was no improvement in fertility and farrowing rate by using RTU instead of A-mode ultrasound under commercial conditions.     

Use of transrectal B-mode ultrasound imaging in bovine pregnancy diagnosis

A 3 MHz ultrasonic transducer was used to make pregnancy diagnoses in 320 milk and beef cows and heifers, on average 41 days after the last insemination. The ultrasound diagnostic findings were systematically confirmed by rectal palpation. Signs of pregnancy were detected as early as the 25th day after insemination. Discounting 16 doubtful results, the accuracy of positive diagnosis (94 per cent) was better than negative diagnosis (89.7 per cent). Ultrasound scanning could be used for the study of embryo mortality or for the determination of fetal age.     

Accuracy of transrectal palpation for early pregnancy diagnosis in Egyptian buffaloes

The present study was undertaken to evaluate the accuracy of transrectal palpation (TRP) for diagnosing early pregnancy in buffaloes and the false diagnoses of the TRP test by using the pregnancy-associated glycoprotein radioimmunoassay (PAG-RIA) test. Pregnancy was diagnosed in 168 buffalo–cows once by TRP and PAG-RIA test between days 31 and 55 after breeding. The sensitivity of TRP for detecting pregnant buffalo–cows was 37.5% at days 31–35, increased to 93.8% at days 46–50 and reached 100% at days 51–55 (P < 0.01). All cases of false negative diagnoses (n = 10) had PAG concentration higher than the threshold (≥1.8 ng/mL) for diagnosing pregnancy. The specificity of TRP for detecting non-pregnant buffalo cows ranged between 90.9%, and 100% between days 31 and 55. All cases of false positive diagnoses (n = 5) made by TRP had PAG concentrations lower than the threshold for diagnosing pregnancy. It could be concluded that TRP is an accurate method for diagnosing pregnant and non-pregnant buffalo cows from day 46 after breeding.     

Oestradiol-17 beta in the milk of cows from 6 days before to 14 days after their insemination.

In artificially inseminated cows (AI on day 1) peak concentrations of oestradiol-17 beta in defatted milk occurred at median times of day 0 during the pre-ovulatory period, days -5 to 2, and day 6 during the post-ovulatory period, days 2-15. Median peak concentrations during these periods were approximately 5 pg/ml and 3 pg/ml respectively. There were no significant differences in the timing or magnitude of oestradiol-17 beta concentrations between cows that became pregnant to the AI and those that entered normal length oestrus cycles immediately after AI.     

Failure of an intramuscular injection of an analogue of gonadotrophin-releasing hormone 11 to 13 days after insemination to increase pregnancy rates in dairy cattle

At 11 to 13 d after insemination, 1028 dairy cows on 19 farms were given an intramuscular injection of 10 micrograms of the GnRH analogue buserelin. Their reproductive performance was compared to 1022 control cows receiving a placebo. The GnRH analogue-treated cows had fewer short interoestrous intervals compared to the control cows, but there were no significant differences in pregnancy rates to either the insemination preceding or following treatment, in calving to conception interval, or to percent pregnant by the end of mating. There were no differences between treatments in herds of high, average or low pregnancy rate, in 2-year-old cows or cows greater than 2-years-old and in cows calved 40 d or less, or greater than 40 d. The use of 10 micrograms of the GnRH analogue, buserelin, 11 to 13 d after insemination, cannot be recommended as a method of improving reproductive performance in dairy herds.     

An evaluation of the gamma interferon test for detecting bovine tuberculosis in cattle 8 to 28 days after tuberculin skin testing

The gamma interferon (IFN -gamma) test was evaluated for its ability to diagnose bovine tuberculosis in cattle that 8 to 28 days previously had a positive caudal fold skin test. The sensitivity of the test was determined in a group of 163 Mycobacterium bovis -infected cattle from 21 herds. The specificity was estimated in a group of 213 cattle which had reacted to a caudal fold test, but were from 82 herds that had no evidence of infection with M bovis. The sensitivity and specificity of the IFN -gamma test was 85 and 93 per cent respectively. No significant differences in the sensitivity and specificity of the test were observed between blood samples that were cultured on the day of collection and those cultured the day after collection. These findings support the use of the IFN -gamma test as a practical serial test that can be used to complement the caudal fold skin test.     

Pregnancy rates in beef cattle after administering a GnRH agonist 11 to 14 days after insemination.

The objective of our study was to determine the dose-pregnancy rate response of a GnRH agonist injected once during the luteal phase in virgin heifers (four locations) and suckled beef cows (two locations) during the spring of 1989. The same treatments in virgin heifers were used at one location in the fall of 1989. Heifers and cows were inseminated at a synchronized estrus and then assigned randomly to each of three doses (0, 100, or 200 micrograms) of fertirelin acetate administered in 4 ml of saline in a double-blind study after being blocked by inseminator and service sire. Injections were given (i.m.) once on d 11, 12, 13, or 14 after estrus. Pregnancy rates were determined by palpation of the uterus per rectum and(or) by actual calving dates. Overall pregnancy rates for heifers across five locations were 86/201 (43%), 100/197 (51%), and 100/203 (49%) for the 0, 100, and 200 micrograms doses of fertirelin acetate, respectively. Pregnancy rates for heifers at two locations based on calving data were 28/48 (50%), 31/47 (66%), and 34/52 (65%) for the three doses. Both the 100- and 200-micrograms doses increased (P less than .05) pregnancy rates in heifers based on palpation results, whereas only the 200-micrograms dose tended to increase (P = .10) pregnancy rates based on calving results. Pregnancy rates based on palpation for suckled beef cows at two locations were 36/51 (71%), 30/43 (70%), and 34/51 (67%), and the corresponding pregnancy rates based on calving results were 30/41 (73%), 32/36 (89%), and 31/38 (82%) for the 0, 100, and 200 micrograms doses, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Accuracy of fetal age estimates using transrectal ultrasonography for predicting calving dates in dairy cows in seasonally calving herds in New Zealand

AIM: To describe the accuracy of transrectal ultrasonography for predicting calving dates in dairy cows under typical New Zealand conditions and to assess potential risk factors for differences between predicted and actual calving dates.

METHODS: Data were collected from 116 seasonally calving herds over 2 years in a retrospective single cohort study. Transrectal ultrasonography was undertaken by experienced veterinarians (n=12) to determine if cows were pregnant, and if so to estimate fetal age. Predicted calving date was calculated by adding 282 days to the estimated conception date. Accuracy was assessed using differences between predicted and actual calving dates for each animal. Potential risk factors for animals calving >10 days before or after their predicted calving date were assessed using multinomial logistic regression models.

RESULTS: The study population comprised 83,104 cows over the 2 years of the study; 75,037 (90.3%) cows calved within 10 days of their predicted calving date, 3,683 (4.4%) calved >10 days earlier, and 4,384 (5.3%) >10 days later, than predicted. Risk factors for calving >10 days before or after the predicted calving date included having >1 artificial insemination (AI) before pregnancy diagnosis (p=0.03), where the cow’s most recent AI was <21 days before the end of the herd’s AI period (p<0.01), and where the diagnosis was made at the second or third herd-visit (p<0.01). The probability of calving being >10 days later than predicted also increased when the fetus was ≥13 weeks old at pregnancy diagnosis (p<0.01).

CONCLUSIONS AND CLINICAL RELEVANCE: In this study, >90% of cows diagnosed pregnant by veterinarians using transrectal ultrasonography calved within 10 days of the predicted calving date. In herds where herd reproductive performance is high, it would be expected that more cows would conceive to their first AI, and potentially fewer cows would have AI close to the end of the herd’s AI period, which would increase diagnostic accuracy. Where herd managers rely on accurate predicted calving dates they should be informed about realistic expected accuracy. For greatest accuracy, a complete AI history should be made available to the person performing the pregnancy diagnoses and cows at most risk of having inaccurate predicted calving dates should be identified.     

Estimation of sensitivity and specificity of pregnancy diagnosis using transrectal ultrasonography and ELISA for pregnancy-associated glycoprotein in dairy cows using a Bayesian latent class model

AIMS: To determine the sensitivity (Se) and specificity (Sp) of pregnancy diagnosis using transrectal ultrasonography and an ELISA for pregnancy-associated glycoprotein (PAG) in milk, in lactating dairy cows in seasonally calving herds approximately 85–100 days after the start of the herd’s breeding period.

METHODS: Paired results were used from pregnancy diagnosis using transrectal ultrasonography and ELISA for PAG in milk carried out approximately 85 and 100 days after the start of the breeding period, respectively, from 879 cows from four herds in Victoria, Australia. A Bayesian latent class model was used to estimate the proportion of cows pregnant, the Se and Sp of each test, and covariances between test results in pregnant and non-pregnant cows. Prior probability estimates were defined using beta distributions for the expected proportion of cows pregnant, Se and Sp for each test, and covariances between tests. Markov Chain Monte Carlo iterations identified posterior distributions for each of the unknown variables. Posterior distributions for each parameter were described using medians and 95% probability (i.e. credible) intervals (PrI). The posterior median estimates for Se and Sp for each test were used to estimate positive predictive and negative predictive values across a range of pregnancy proportions.

RESULTS: The estimate for proportion pregnant was 0.524 (95% PrI?=?0.485–0.562). For pregnancy diagnosis using transrectal ultrasonography, Se and Sp were 0.939 (95% PrI?=?0.890–0.974) and 0.943 (95% PrI?=?0.885–0.984), respectively; for ELISA, Se and Sp were 0.963 (95% PrI?=?0.919–0.990) and 0.870 (95% PrI?=?0.806–0.931), respectively. The estimated covariance between test results was 0.033 (95% PrI?=?0.008–0.046) and 0.035 (95% PrI?=?0.018–0.078) for pregnant and non-pregnant cows, respectively. Pregnancy diagnosis results using transrectal ultrasonography had a higher positive predictive value but lower negative predictive value than results from the ELISA across the range of pregnancy proportions assessed.

CONCLUSIONS AND CLINICAL RELEVANCE: Pregnancy diagnosis using transrectal ultrasonography and ELISA for PAG in milk had similar Se but differed in predictive values. Pregnancy diagnosis in seasonally calving herds around 85–100 days after the start of the breeding period using the ELISA is expected to result in a higher negative predictive value but lower positive predictive value than pregnancy diagnosis using transrectal ultrasonography. Thus, with the ELISA, a higher proportion of the cows with negative results will be non-pregnant, relative to results from transrectal ultrasonography, but a lower proportion of cows with positive results will be pregnant.     

Growth and plasma metabolites of lambs weaned to legume pasture at 28 days of age

Two trials evaluated the potential for weaning lambs directly onto legume pasture at 28 d of age. Ewes and their twin-reared lambs were placed in paddocks on d 19; ewes were removed on d 28. In Trial 1, 60 lambs were allocated to three treatments: unweaned controls (CON1), lambs weaned onto first-cut alfalfa either without supplementary grain (WOG) or with up to 270 g.hd-1.d-1 supplementary grain (WG). Daily gains for the CON1, WOG and WG lambs were 309, 118 and 159 g for the period from d 28 to 40 (P greater than .05) and 241, 195 and 245 g for the period from d 40 to 56 (P greater than .05), respectively. In Trial 2, 80 lambs were allocated to four treatments: weaning onto first-cut alfalfa (early alfalfa, EA), second-cut alfalfa (late alfalfa, LA) birdsfoot trefoil (BFT) and unweaned controls (CON2, pastured on second-cut alfalfa). Daily gains for CON2 lambs were greater (P less than .05) than gains of EA and LA lambs (327 vs 136 and 136 g, respectively) for d 28 to 40, but not different (P greater than .05) for d 40 to 56 (245, 227 and 195 g, respectively). Gains for BFT lambs were lower (P less than .05) than for CON2 lambs for both periods (122 and 136 g, respectively), and BFT lambs appeared to be unthrifty after weaning. By d 32, weaning caused plasma glucose to decline 16.0 mg/dl and plasma nonesterified fatty acids to increase 365 mu eq/liter from preweaning levels. Hematocrit values ranged from 31 to 35% (Trial 1) and 25 to 29% (Trial 2), suggesting that the weaned lambs did not suffer from dehydration. Crossbred lambs can be weaned at 28 d of age directly onto first-cut or second-cut alfalfa.     

Accuracy of ultrasonography in the detection of severe hepatic lipidosis in cats.

The accuracy of ultrasonography in detection of feline hepatic lipidosis was studied retrospectively. The following ultrasonographic criteria were associated positively with severe hepatic lipidosis: the liver hyperechoic, compared with falciform fat; the liver isoechoic or hyperechoic, compared with omental fat; poor visualization of intrahepatic vessel borders; and increased attenuation of sound by the liver. In a group of 36 cats with clinically apparent hepatobiliary disease and in which liver biopsy was done, liver hyperechoic, compared with falciform fat, was the best criterion for diagnosis of severe hepatic lipidosis with 91% sensitivity, 100% specificity, and 100% positive predictive value.     

Comparison of pregnancy per AI of heifers inseminated with sex-sorted or conventional semen after oestrus detection or timed artificial insemination

The objective of the study was to compare the fertility after using sex-sorted or conventional semen either with oestrus detection (EST) or timed artificial insemination (TAI) in Holstein heifers. Holstein heifers were randomly assigned to one of the following treatments in a 2 × 2 factorial design. Heifers in the EST group were inseminated with sex-sorted (n = 114) or conventional semen (n = 100) after spontaneous or induced oestrus. Heifers in the TAI, subjected to the 5-day Cosynch+Progesterone protocol (GnRH+P4 insertion-5d-PGF_2α+P4 removal-1d-PGF_2α-2d-GnRH+TAI), were inseminated with sex-sorted (n = 113) or conventional semen (n = 88). Statistical analyses were performed using PROC GLIMMIX procedure of SAS 9.4 (SAS Institute Inc., Cary, NC). Overall P/AI was 60.7% for EST and 54.2% for TAI regardless of types of semen and 68.1% for conventional and 48.9% for sex-sorted semen regardless of insemination strategies. Fertility of heifers inseminated with either sex-sorted (53.5%; 44.2%) or conventional (69.0%; 67.0%) semen did not differ between EST and TAI respectively. Besides, the interaction between the semen type and the insemination strategy was not significant for P/AI. The embryonic loss was significantly greater with sex-sorted semen (17.1%) compared to conventional semen (1.6%). There was no sire effect with sex-sorted semen on P/AI (52.6% vs. 46.2%) and embryonic loss (16.4% vs. 18.0%). As expected, sex-sorted semen resulted in more female calves (89.8% vs. 51.6%) than conventional semen. Thus, sex-sorted semen can be used with 5-day Cosynch+Progesterone protocol to eliminate the inadequate oestrus detection and to increase female calves born in dairy heifers.     

Accuracy of pregnancy/non pregnancy diagnosis in zebu and crossbred cattle and Murrah buffaloes by milk progesterone determination post insemination

Tropical Animal Health and Production - Milk samples collected on days 0, 6, 20, 22 and 24 post insemination from Sahiwal and Tharparkar (zebu) cows, Karan Swiss (Sahiwal × Brown Swiss) and...     

Serum thyroxine concentrations and pregnancy rates 15 to 16 days after ovulation in broodmares

OBJECTIVE: To determine whether serum thyroxine (T4) concentration was associated with pregnancy rates 15 to 16 days after ovulation in mares and to determine whether thyroid hormone supplementation would enhance fertility in mares. DESIGN: Cohort study. ANIMALS: 329 clinically normal broodmares. PROCEDURE: Mares were examined 15 to 16 days after ovulation to determine whether they were pregnant; blood samples for determination of serum T4 concentration were collected at the same time. Sixty mares were receiving thyroid hormone supplementation prior to the study because of low serum T4 concentration (< 16 microg/dl) prior to breeding. RESULTS: Serum T4 concentration ranged from 4.5 to 53.9 mg/dl. Forty (12%) mares had low (< 16 microg/dl) concentrations, 283 (86%) had normal concentrations, and 6 (2%) had high (> 45 microg/dl) concentrations. Two hundred thirty-one mares were pregnant 15 to 16 days after ovulation. A significant association between serum T4 concentration (low, normal, or high) and pregnancy (yes or no) was not detected, and logistic regression analysis indicated that serum T4 concentration was not significantly related to pregnancy. Of the 269 mares not receiving thyroid hormone supplementation, 187 were pregnant, and of the 60 mares receiving thyroid supplementation, 44 were pregnant. There was no significant relationship between thyroid hormone supplementation and pregnancy status. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that serum T4 concentration in mares is not significantly associated with pregnancy 15 to 16 days after ovulation. Results also suggest that supplementation of mares that only have low T4 concentrations is not indicated or likely to be beneficial.