Corpus Luteum Size Research Articles

Effects of β-carotene supplementation and age on the oxidative status, production and reproductive performance of grazing ewes

Context There is some evidence that physiological stages such as breeding, pregnancy, parturition and lactation may trigger oxidative stress. It has also been observed in several species, including sheep, that age affects their vulnerability to oxidative stress. Aims This study investigated the effects of supplemental β-carotene and age on the oxidative status of grazing ewes around breeding, pregnancy, parturition and early lactation as well as on their production and reproduction performance. Methods Hundred and four ewes were divided into two broad age groups (young = 1–3 years, and old = 4–6 years). Within age groups, ewes of similar age were randomly assigned to four treatment groups (A1, A2, A3, C) by using a completely randomised block design. The young (n = 13) and old (n = 13) sheep in Groups A1, A2 and A3 were daily drenched with 100 mg, 75 mg and 50 mg β-carotene respectively. Group C was unsupplemented (Control). Supplementation lasted 28 days before oestrus synchronisation; 14 days during oestrus synchronisation (CIDR) and hand-mating; 18 days post-hand-mating; 30 days before lambing; and 15 days after lambing. All animals were grazed on Kikuyu grass (Pennisetum clandestinum). Six ewes from each group (total = 24) were sampled for blood to measure oxidative and hormonal status during the experiment. Key results Supplemental β-carotene at ≥75 mg/day may act as a pro-oxidant in ruminants under oxidatively stressed conditions such as parturition. Age did not affect the ewes’ oxidative status. The supplemental β-carotene did not affect bodyweight, oestrus parameters, corpus luteum size, conception rate and litter size. Except for a tendency of lambs from supplemented ewes to have heavier weight at 15 days old (P = 0.080), age group and supplemental β-carotene did not affect the lamb mortality rate or weight at birth or 15 days old. Older ewes showed earlier and longer duration of oestrus than did younger ewes. Conclusions Supplementation of grazing ewes with β-carotene should not be ≥75 mg/day, especially at parturition period, because it may work as a pro-oxidant. The older ewes seem to have earlier oestrus with a longer duration than do the younger ones. Implications Caution is urged when administering high doses of β-carotene to ewes during the peri-parturient period.

Effect of an additional GnRH two days after the initiation of a resynchronization program 25 days after artificial insemination on fertility of lactating dairy cows

We investigated the effect of an additional GnRH 2d after initiation of resynchronization on d25 post-AI on the proportion of cows without a corpus luteum (CL) at nonpregnancy diagnosis (NPD) and pregnancy per AI (P/AI) of cows with a CL at NPD that were reinseminated. Once per week, cows that were inseminated 25d earlier were randomly assigned to receive either a GnRH treatment only (G25) or GnRH on this day and 2d later (G25&27). Pregnancy diagnosis and CL presence were determined d32 post-AI using ultrasonography. Nonpregnant cows with a CL were enrolled in different strategies for resynchronization of ovulation according to parity (primiparous or multiparous) and CL size. Primiparous and multiparous cows with a CL ≥ 20 mm in diameter continued Resynch-25 (PGF2α on d32; PGF2α on d33; GnRH on d34; and AI on d35). Multiparous cows with CL < 20 mm restarted a modified Ovsynch at NPD (GnRH – 7d – PGF2α – 1d – PGF2α – 1d – GnRH – 1d – AI). Primiparous cows with CL diameter < 20 mm started an Ovsynch+CIDR protocol on the day of NPD (GnRH + CIDR inserted – 7d – PGF2α + CIDR removed – 1d – PGF2α – 1d – GnRH – 1d – AI). Cows without a CL were not enrolled in any resynchronization program for a week and were excluded from fertility analyses. Only in multiparous cows, the additional d27 GnRH treatment was associated with a decreased P/AI 32d and 102d post-AI for the insemination before treatment. The overall proportion of nonpregnant cows without CL did not differ between treatments. Yet, the GnRH treatment 27d after AI tended to increase the proportion of overall nonpregnant cows with CL < 20 mm at NPD. Treatment did not affect fertility parameters of primiparous cows with a CL ≥ 20 mm that continued Resynch-25 at NPD. Primiparous cows in G25&27 with CL < 20 mm and submitted to Ovsynch+CIDR at NPD tended to have decreased P/AI 102d after AI and calving/AI. When fertility parameters of primiparous cows with a CL independent of size at NPD were analyzed combined, no effect of treatment was observed. Treatment did not affect fertility of multiparous cows with CL < 20 mm enrolled in Ovsynch at NPD. Multiparous cows in the G25&27 group that had a CL ≥ 20 mm and continued Resynch-25 at NPD tended to have a greater calving/AI due to a decreased total pregnancy loss. In summary, no treatment effect was observed on the overall fertility of primiparous cows with CL at NPD. In multiparous cows, G25&27 was associated with a decreased fertility of the previous AI, but it tended to increase calving/AI for multiparous cows with CL at NPD by decreasing the total pregnancy loss for the AI after treatment.

Conception rate according to the size and location of corpus luteum and coexistent follicle before embryo transfer in Hanwoo

Conception rate according to the size and location of corpus luteum and coexistent follicle before embryo transfer in Hanwoo

130 Effect of an appeasing substance application on growth, stress, handling quality and reproduction of Bos indicus beef heifers synchronized to fixed-time AI

Abstract This experiment evaluated the effects of an analogue of bovine appeasing substance (BAS) on growth, stress, handling quality, and reproduction of Nellore heifers. Twenty-nine heifers [body condition score (BCS) = 4.84 ± 0.13; body weight (BW) = 371 ± 0.77 kg; 23 ± 2 months of age)] were assigned to 1 of 2 treatments: 1) Saline solution (0.9 NaCl; n = 14) or BAS (Secure Cattle, IRSEA Group, Quartier Salignan, France; n = 15). Both solutions were applied topically in the nuchal skin area (5 mL/heifers) at the beginning (d -9) of the fixed-time artificial insemination protocol (FTAI). Heifers were allocated in two different pastures according to the treatment (one pasture per treatment) for 15 d (time of action of BAS) and then combined in a single group (both treatments in the same pasture). Heifers were inseminated on d 0, and BW and BCS were collected on d -9 and 40. The temperament in the squeeze chute (entry and exit scores; scale 1 – 3; chute score; scale 1 – 5; greater values mean more reactive heifers) and blood samples were collected on d -9, 0, 7, 14 and 30. The percentual of aggression, accident, and dirtiness in the perineal region were evaluated on d 0 along with time to inseminate, estrus expression scores (scale 1 – 3; 1 = no expression, 2 = low expression, 3 = greater expression), and dominant follicle size. The corpus luteum size was measured on d 7 and 14, and the pregnancy and embryo size on d 40. The BAS vs. Saline-treated heifers tended to have greater BW change (23.6 vs. 20.8 ± 1.03 kg; P = 0.09) and had greater BCS change (0.05 vs. -0.21 ± 0.05; P &amp;lt; 0.01). The BAS vs. Saline-treated heifers tended to have lesser entry scores (1.42 vs. 1.67 ± 0.09; P = 0.09) and percentual of dirtiness in the perineal region (48.3 vs. 71.1 ± 8.67 %; P = 0.06), and no effects of treatment were detected (P ≥ 0.39) for chute score, exit score, aggression, accident and time to inseminate. The BAS vs. Saline-treated heifers had greater estrus scores (2.00 vs. 1.27 ± 0.21; P = 0.03), and no effects were detected (P ≥ 0.11) for ovarian variables, pregnancy rate, and conceptus size. Furthermore, no treatment effects were detected (P ≥ 0.25) for serum concentration of cortisol and plasma concentration of haptoglobin, ceruloplasmin, and progesterone. Therefore, BAS application at the beginning of the FTAI protocol could decrease the temperament and dirtiness in the perineal region and increase the growth and estrus expression of beef heifers.

Effect of heatwaves on the pregnancy rate of dual-purpose recipient cows transferred with produced in-vitro embryos in tropical locations

Dual-purpose cows (n=648) from different genetic group (European, Zebu and crossbreeds cattle) were transferred with embryos produced in-vitro, in fresh or thawed, with the purpose of analyzing the effects of heatwaves on the pregnancy rate (PR) before, during, and after the transfer. The weather data used (temperature and humidity) were obtained on-site in production units to determine the temperature-humidity index (THI), and it was established that THI values of ≥74 before (-4, -3 and -2 days), during (-1, 0 and +1), and after (+2, +3 and +4) the transfer constitute a heatwave, with day “0” being the transfer day. The 2K contingency table was used, with a xi2 distribution and logistic regression (Statistica, v10), to find the PR in the recipient cows. The intrinsic variables considered were the corpus luteum size (CL1, CL2 and CL3), body condition, parity, and genetic group; while the extrinsic variables were the geographical area, embrionary development stage, embryo preservation method and quality. The presence of a heatwave before, during and after the transfer lowered the PR by 13% (p&lt; 0.05), with it being 43% in conditions of thermal comfort, and 30% during a heatwave, the odd ratio was 0.6404 - 0.4652. The PR was lower in the presence of a heatwave across the three genetic groups (30.09, 33.33 and 35.20% by Zebu, European, and crossbreeds cattle, respectively), as well as in cows with smaller CL (CL3, 29.38%). Body condition, parity and embrionary development stage were not associated with the heatwave (p&gt;0.05). Thawed embryos are more susceptible to heatwaves, their PR being lower (16.81%). It was concluded that the heatwave lowered the PR of the recipient cows by 13%.

Does GnRH treatment at TAI regardless of estrus occurrence increase pregnancy rate in crossbred Bos taurus suckled cows?

The impact of GnRH treatment on the day of TAI in beef cows has received limited investigation, especially concerning its association with estrus expression. Consequently, two experiments were conducted to assess the potential of GnRH treatment on the day of TAI to enhance fertility according to the expression or not of estrus in beef cows. Experiment 1 aimed to determine ovulation rate and luteal function, while Experiment 2 aimed to determine the effect of the two GnRH treatment approaches on pregnancy rate. In Experiment 1, multiparous Brangus suckling cows (n = 17) were submitted to an 8-day TAI protocol. Estrus occurrence was evaluated based on chalk removal on D10 (TAI) and cows were assigned to receive GnRH (25µg lecirelin; im) according to the group: GnRH (n = 7), regardless of estrus expression; or selectGnRH (n = 10), only cows not detected in estrus. Ovulation rate occurring until 77h after IVD removal did not differ (p = 0.17) between GnRH (85.7%; 6/7) and selectGnRH (100%; 10/10). Also, corpus luteum size and serum progesterone concentration were not affected (p>0.05) by treatments. In Experiment 2, crossbred taurine suckled cows (n = 384) were submitted to the same protocol as described in Experiment 1 and were randomly allocated to GnRH or selectGnRH groups. There was no difference in P/AI between groups (selectGnRH = 55.6%; GnRH = 54.3%; p = 0.7) 30 days after TAI. As expected, there was a pronounced effect (p<0.0001) of estrus expression on P/AI (Estrus = 61.5%; No estrus = 33.0%), regardless of group. In summary, ovulation timing and rate and luteal function did not differ between groups. Also, GnRH administration only in cows that do not show estrus is recommended, considering hormone savings and similar conception rate.

Comparison of two methods to measure the area of ultrasonography images of corpus luteum in sheep

Ultrasonography (US) is a helpful tool for studying follicular and luteal dynamics, ovulation, and embryo development. However, there is currently no gold standard reference technique for estimating the size of the corpus luteum (CL). The aim of this study was to compare the results from measuring ewes’ CL size based on its’ diameter or its’ surface with the aid of image software. The study involved 19 ewes, recording the images of 50 CLs at different stages of development, and therefore, calculating its’ size by both procedures. The results showed that measuring the CL diameter to calculate its’ area is a rapid and reliable technique that can effectively substitute the measurement of the surface, which requires precision and time. The study concluded that measuring the two main axes of the CL is a valid method for effectively estimating its size.

Relationships between follicle and corpus luteum size and vascularization with ovulation, progesterone production, and pregnancy in Nellore beef cattle

Relationships between follicle and corpus luteum size and vascularization with ovulation, progesterone production, and pregnancy in Nellore beef cattle

Sonographic studies on the significance of follicle size and corpus luteum morphology in dairy cows after insemination

In dairy cattle, numerous factors determine the success of an insemination. The aim of the present study was to generate findings concerning the association between the preovulatory follicles, the corpora lutea with or without cavities and pregnancy in dairy cows under field conditions. Data was obtained from 176 dairy cows scheduled for artificial insemination. The cows were gynecologically examined using sonography at the time of insemination, 24 hours later, on day 9, on day 34 and after day 42 after insemination. Additionally, blood samples were collected from the coccygeal vein at the time of insemination and on day 9 in order to determine blood progesterone level. Depending on the result of the pregnancy test, no difference was detected between the dimensions of the follicles, corpora lutea as well as their cavities and progesterone levels 9 days after insemination in the dairy cows with spontaneous ovulations. In contrast to the corpus luteum without cavity, the surface area of the corpus luteum with cavity remained constant during the study period, while at the same time the cavity decreased in size to a significant degree. In addition, breed differences in corpus luteum sizes were detected on day 34. No cause was detected for the formation of cavities in corpora lutea and there was no link to the follicle from which the corpus luteum developed. Both the changes in corpus luteum sizes over time and their breed-related differences could have an impact on insemination outcome.

Conception rate and pregnancy loss in fixed-time cattle embryo transfer programs are related to the luteal blood perfusion but not to the corpus luteum size

This study aimed to evaluate the effect of luteal blood perfusion and corpus luteum (CL) area on the conception rate and occurrence of pregnancy loss of recipients in a large-scale fixed-time embryo transfer (FTET) program. Multiparous Brangus cows (n = 1700) at 45 days postpartum and body condition scores (BCS) between 2.5 and 4.0 (3.0 ± 0.3) were used in this study. On a random day of the estrous cycle (day −10), the females received progesterone and estradiol based on the FTET protocol. On day 7, 1465 recipients had at least one CL and were evaluated using B-mode ultrasound for the CL area (cm2) and color Doppler for the luteal blood perfusion score (I/low-vascularization area <40% of the CL; II/medium-vascularization >45% to < 50%; and III/high-vascularization >50%). Immediately after CL evaluation, each recipient received a single fresh embryo (blastocyst stage) ipsilateral to the CL, in vitro produced from a commercial laboratory. Pregnancy diagnosis was performed at 30 days and repeated 60 days later to evaluate pregnancy loss (30–90 days). Ultrasound evaluation and embryo transfer were performed by a single technician. For data analysis, in addition to luteal blood perfusion groups, recipients were retrospectively ranked according to CL area into small (<3 cm2; 2.63 ± 0.01), medium (>3 to < 4 cm2; 3.44 ± 0.01), and large (>4 cm2; 4.77 ± 0.03). Data were analyzed using a logistic regression model (P < 0.05). The overall conception rate was 44.2% (648/1465), influenced by the luteal blood perfusion score [P = 0.03; high 48.4%a (134/277), medium 44.6%a (427/958), and low 37.8%b (87/230)] but not by CL area ranking [P = 0.37; large 41.8% (225/538), medium 45.2% (276/610), and small 46.4% (147/317)]. There was no interaction between the luteal blood perfusion score and CL area ranking (P = 0.81), and the BCS did not affect the results of this study (P = 0.51). In terms of pregnancy loss up to 90 days, there was no effect on the CL area ranking (P = 0.77), but the flow score showed an effect [P = 0.03; high 3.6%b (5/139), medium 9.3%a (44/471), and low 10.3%a (10/97)]. The conception rate and occurrence of pregnancy loss in the FTET program in beef cattle are related to luteal blood perfusion but not CL size.

Ovarian morphology and follicular dynamics associated with ovarian aging in Bos indicus beef cows

This study characterizes the ovarian volume, antral follicle count (AFC), and ovarian dynamics of cows at different ages. Nellore cows (Bos taurus indicus) were used in two experiments. In Experiment 1, 57 lactating cows ranging in age from 3 to 23 years had their estrous cycle synchronized based on progesterone/estradiol treatments. The ovaries were scanned by ultrasound to record ovarian volume and AFC prior to follicle aspiration (AFC1). A second AFC (AFC2) was performed 5 days later to count only the growing antral follicles. In Experiment 2, six long-lived (14- to 23-year-old) and three young (4- to 8-year-old) non-lactating cows were submitted to daily ovarian scanning ultrasound during an interovulatory interval. Blood samples were collected during the estrous cycle to assess serum progesterone concentration. Data were analyzed using Student's t-test, ANOVA, and regression analysis tests. In Experiment 1, there were more (P < 0.05) antral follicles in AFC1 (31.4 ± 3.5) than in AFC2 (22.6 ± 2.4). In AFC1, the volume of the right ovary (6.03 ± 0.5 cm3) was greater (P < 0.01) than that of the left one (4.53 ± 0.4 cm3), although the AFC did not differ between the two ovaries (15.3 ± 1.8 and 16.3 ± 1.8, respectively). In both AFC1 and AFC2, there was a decline in the number of antral follicles as the age of the cow increased (P < 0.01). Ovarian volume (average of both ovaries) was related (P < 0.01) with AFC (R² = 0.1499) and cow age (R² = 0.0911). In Experiment 2, young and old cows under the age of 20 had a pattern of follicular growth waves, while cows over 20 years old did not have waves of follicular growth. The progesterone profiles and corpus luteum size during the estrous cycle did not differ between the groups. In conclusion, although cows had increased ovarian volume and decreased follicular population as they age, the follicular growth pattern and corpus luteum functionality appear to be unaffected by age.

Ovarian response and conception rate in Boran and Boran*Holstein cows treated by Gonadotrophin-realizing hormone and ProstaglandinF2α with and without exogenous progesterone

BackgroundDifference in breed, nutrition status and climate in which animals are managed result in differences in response to reproductive hormones. Fertility rate to artificial insemination is very low in Ethiopian Boran and Boran*Holstein crosses. This partly maybe due to adopting estrus and/or ovulation synchronization developed for temperate taurine cattle. Experimental study was conducted to evaluate ovarian response to combinations of Gonadotrophin-Realizing Hormone agonist (gonadorelin) and ProstaglandinF2α (PGF2α) with or without progesterone (Controlled Internal Drug Release/CIDR), and conception rate to timed AI. Postpartum native Ethiopian Boran (n = 60) and Boran*Holstein cross (n = 66) cows were randomly assigned to four treatment groups as Ovsynch (gonadorelin on day of start, PGF2α seven days later, 2nd gonadorelin at 48 h of PGF2α and insemination at 19 h of the 2nd gonadorelin); CIDR + Ovsynch (same as Ovsynch but CIDR device was inserted into vagina for 7 days); Cosynch (same as Ovsynch but insemination was made at the 2nd gonadorelin) and CIDR + Cosynch (same as Cosynch but CIDR was inserted for 7 days).ResultThere was no difference (P > 0.05) in ovulation rate to day 9 gonadorelin (88.33% in Boran; 78.79% in Boran*Holstein) and interval from day 9 gonadorelin to ovulation (36.5 ± 1.13 h in Boran and 36.057 ± 1.11 h in Boran*Holstein). Dominant follicle immediate to ovulation (14.95 ± 0.19 mm Vs 19.12 ± 0.49 mm) and corpus luteum size (16.31 ± 0.33 mm Vs 20.28 ± 0.43 mm ) respectively were smaller (P < 0.05) in Boran than Boran*Holstein. Plasma progesterone concentration at PGF2α was higher (P < 0.05) in Boran (11.91 ± 0.74ng/mL) than Boran*Holstein (6.13 ± 0.27ng/mL) but luteolysis rate was lower (P < 0.05) in Boran (87.9%) than Boran-Holstein (96.9%). Cows with CIDR had higher conception rate than cows without CIDR (72.00% Vs 39.02% in Boran*Holstein and 74.07%, Vs 51.52% in Boran respectively). Insemination at 19 h of gonadorelin administration resulted in higher conception rate (78.6% for Boran; 71.43% for Boran*Holstein) than insemination at gonadorelin (69.29% for Boran; 66.67% for Boran*Holstein).ConclusionBoran cows have smaller preovulatory follicles, smaller corpus luteum, large amount of progesterone and lower rate of luteolysis to PGF2α compared to Boran*Holstein. The CL of Boran cattle seems les reactive to PGF2α than Boran*Holstein CL. CIDR significantly improved conception rate in Boran and Boran*Holstein cows.

Ultrasonographic and Doppler characteristics of corpus luteum luteogenesis in Remonta Argentino jennies

The corpus luteum (CL) plays a crucial role in maintaining pregnancy and preparing the uterus for implantation of the fertilized egg. Transrectal Doppler ultrasonography of the ovary can be used as a diagnostic tool to assess the reproductive status and functionality of the CL. Our aim was to characterize size, echogenicity and degree of vascularization of the corpus luteum over five days after ovulation in Remonta Argentino jennies. Five healthy cycling jennies aged 9 to 14 years were monitored transrectally using the MyLabTMOne ultrasound (ESAOTE, InMed, Argentina) with a 5-10 MHz linear array transducer. After a preovulatory follicle was detected, jennies were monitored daily for ovulation (day 0) and ultrasonographic evaluation of the CL until day 5. Two ovulations and the respective CL formation were analyzed in each jenny (n=10 CL). Size and echogenicity were evaluated using B mode and CL vascularization using the Doppler-color function, with a pulse repetition frequency of 1.2 MHz. All ultrasound examinations were video recorded for analysis. Adobe Premiere Pro CS6® was used to collect three images from each video where the largest area of the CL and the highest Doppler signal were detected. Image J. version 1.52i software (National Institute of Health, USA) was used to analyze images and to determinethe area, number of gray pixels (echogenicity) and color area within the CL in Doppler mode. The average value from the three images was used to determine CL size (area in cm2), echogenicity (average gray pixel intensity) and the proportion of vascularized area (AV; area with blood flow/total CL area x 100). Spearman's test was used to correlate the variables and the changes recorded between days 1 and 5 of diestrus. The results obtained on each day were the following (values expressed as mean±SEM): Day 0: area 3.26±0.5; echogenicity 84.2±4.86; AV 5.54±1.75; Day 1: area 4.86±0.32; echogenicity 91.25±7.42; AV 1.84±0.26; Day 2: area 4.83±0.41; echogenicity 88.72±7.89; AV 3.51±0.81; Day 3: area 4.64±0.43; echogenicity 89.69±4.9; AV 4.54±0.67; Day 4: area 4.38±0.48; echogenicity 97.78±7.61; AV 5.8±1.06; Day 5: area 4.24±0.49; echogenicity 89.18±9.25; AV 8.66±1.15. No statistical correlation was observed either between variables or with the day of diestrus (p>0.05). Blood samples were collected daily between day 0 and day 5 of diestrus and progesterone determinations are ongoing. Our results contribute to a better understanding of CL formation in Remonta Argentino donkeys that could potentially be used to determine CL age and function.

Comparison between transrectal palpation, B-mode and Doppler ultrasonography to assess luteal function in Holstein cattle.

Over the years, the most common methods for monitoring reproductive health in cattle have varied from transrectal palpation to B-mode ultrasonography. Nowadays, some portable ultrasound equipment includes the Doppler mode. Therefore, the aim of this study was to compare the accuracy of the different methods to assess corpus luteum (CL) functionality. In Experiment 1, 53 Holstein lactating cows undergoing a synchronization protocol were examined via transrectal palpation and B-mode scanning. Measurements for the largest diameter (LAD) and subjective size of CL (SCLS) were collected. Data were analyzed using correlation analysis and ROC Curves. In Experiment 2, 30 Holstein non-lactating cows with a CL were administered PGF2α and examined several times after injection, first in B-mode and then with Power Doppler. Measurements for LAD, CL area (CLA) and subjective and objective CL blood flow were collected. Blood samples were taken in both experiments to determine P4 concentration. Data were analyzed using correlation analysis and the GLM repeated measures test. Results for Experiment 1 showed that LAD was more accurate than SCLS. In Experiment 2, CLA was the best measurement to assess CL function, although both subjective and objective CL blood flow offer accurate information 24 h after PGF2α administration. Consequently, ultrasonography provides more accurate information about CL function than transrectal palpation. Although CLA seems to be an earlier indicator of luteal function than blood flow, 24 h after the onset of luteolysis, both parameters are valid.

Evaluation of Corpus Luteum and Plasma Progesterone the Day before Embryo Transfer as an Index for Recipient Selection in Dairy Cows.

The aim of the present study was to evaluate the effects of synchronization method, season, parity, corpus luteum (CL) size, and progesterone (P4) levels on the pregnancy rate after bovine embryo transfer (ET). Among 165 recipient candidates who received 1 of 2s estrus synchronization treatments, 96 heifers and 43 cows were selected through rectal examination and used as recipients. The day before ET, the CL size and plasma P4 concentration were evaluated. The CL sizes and plasma P4 levels were not different between the selected and unselected candidates, and the pregnancy rates with the two synchronization methods were not different. However, the pregnancy rates were higher in heifers than in lactating cows, and also higher after ET performed from September to February than from March to August (p < 0.05). The recipients with a CL larger than 1.5 cm showed statistically higher pregnancy rates, and although there was no statistical significance, the pregnancy rate was higher when the plasma P4 levels were between 2.0 and 4.0 ng/mL. Exposure to a stressful environment and repeated manipulations can reduce the success rate of ET, and recipient selection with an optimal CL size and P4 level can increase the success rate of ET.

Effects of two protocols of ovulation synchronization on corpus luteum size and blood flow, progesterone concentration, and pregnancy rate in beef heifers

The objective of this study was to evaluate the effect of 7-day estradiol-progesterone-based [Treat(C)] and 5-day Co-Synch plus progesterone [Treat(Co-Sy)] protocols on ovulation time, pre-ovulatory follicle diameter, corpus luteum (CL) size and blood flow, progesterone (P4) concentration and pregnancy rate (PR) in beef heifers. In Experiment 1, a crossover design was applied (n = 9). For Treat(C), a progesterone intravaginal (PI) device was inserted, plus 2 mg of estradiol benzoate (day 0). On day 7, 500 µg of cloprostenol plus 0.5 mg of estradiol cypionate were administered, and PI was removed. For Treat(Co-Sy), on day 0, a PI was inserted plus 100 µg gonadotropin-releasing hormone (GnRH). On day 5, PI was removed, plus 500 µg of cloprostenol and 100 µg of GnRH were administered at 69–70 h later. From day one to ovulation day, dominant follicle was evaluated by ultrasonography. On days 4 and 8 post-ovulation, CL was evaluated by color Doppler, and P4 concentration was determined by chemiluminescence. In Experiment 2, a split-plot experimental design was used. Protocols followed were the same as in Experiment 1 [Treat(C); n = 310 and Treat(Co-Sy); n = 314]. Heifers were fixed-time artificially inseminated. Pregnancy was determined on day 41. In Experiment 1, the interval between PI removal and ovulation time was different between protocols (P < 0.01). In addition, P4 concentration was related to the CL size (P < 0.001), CL blood flow (P < 0.01) and protocols (P < 0.03). In Experiment 2, PR did not differ between protocols.

Effect of Strategic Supplementation of Dietary By-Pass Linseed Oil on Fertility and Milk Quality in Sarda Ewes.

The aim of the present study was to assess whether the strategic supplementation of bypass LO can enhance reproductive indexes-fertility, lambing rate, and prolificacy-in dairy Sarda ewes at the end of lactation. To assess whether LO supplementation leads to the adsorptions of PUFAs and their subsequent utilization by the body tissues, milk composition and fatty acid content were analyzed. Forty-eight ewes were assigned to the following groups: the control group (CT; N = 24), fed with a control diet without LO; and the treatment group (LO; N = 24), fed with a diet supplemented with LO (10.8 g/ewe/day). Both diets had similar crude protein and energy levels and were offered for 38 days (-21 to +17 days after artificial insemination). The trial included an adaptation period (7 days) followed by a regular supplementation (31 days) period. Estrus synchronization was induced in all the ewes using an intravaginal sponge and equine chorionic gonadotropin. Fifty-five hours after pessaries withdrawal, all ewes were inseminated using the cervical route and fresh semen. Cholesterol (p &lt; 0.01), high-density lipoprotein (p &lt; 0.001), and triglyceride (p &lt; 0.05) levels in plasma were higher in the LO group. Plasmatic levels of non-esterified fatty acids were lower in the LO group after the end of the supplementation period (p &lt; 0.05). Milk unsaturated fatty acids (UFAs), monounsaturated fatty acids (MUFAs), total polyunsaturated fatty acids (PUFAs), PUFAs omega 3 (PUFAs-ω3) and 6 (PUFAs-ω6), and trans fatty acids were higher in the LO group (p &lt; 0.001), while saturated fatty acids (SFAs) were higher in the CT group during the supplementation period (p &lt; 0.001). Three days after the end of the supplementation period, the content of milk UFAs (p &lt; 0.05), PUFAs (p &lt; 0.001), MUFAs, and PUFAs-ω6 (p &lt; 0.01) were still higher in the LO group. whereas SFA was higher in the CT group (p &lt; 0.01). There was no difference between groups in terms of ovulation rate, progesterone levels in plasma, fertility rate, prolificacy, and total reproductive wastage. However, the total area of luteal tissue was higher in the LO group (p &lt; 0.01). Results obtained demonstrated that LO supplementation exerts a positive role in corpus luteum size at the onset of the peri-implantation period in Sarda dairy ewes. Additionally, the results obtained in the present study showed that the use of dietary bypass LO affects lipid metabolites in plasma and milk fatty acid profiles, demonstrating the ALA uptake by body tissues.

Seasonal influence on the luteal growth and regression characteristics of crossbred dairy cows of Kerala

The study was aimed at investigating the effect of seasonal changes on luteal growth and regression characteristics in crossbred (CB) cows of Kerala. The seasons of the year were classified as rainy (June-September), post-monsoon (October-January) and summer (February- May). In each season, nine healthy regularly cycling CB lactating pluriparous cows were selected for the study. Luteal growth and regression pattern were studied at 24 h intervals from one ovulation to the next ovulation, by transrectal ultrasound (TRUS) examination of the ovaries. During the study period, parameters like the day of earliest detection of corpus hemorrhagicum (CH), size at detection, maximum size of corpus luteum (CL), the day of CL with maximum diameter, day of onset and completion of CL regression were recorded and compared between seasons. Corpus hemorrhagicum was detected one day after ovulation in 55.60, 66.70 and 80 per cent of animals during rainy, post-monsoon and summer seasons, respectively. There existed no statistically significant difference in the size of CL, either on the day of first detection or on the day of maximum size attainment. However, CL during the rainy season needed a significantly (P&lt;0.05) longer period to attain maximum size (10.33 ± 0.58), compared to the post-monsoon (8.33 ± 0.62) and summer seasons (8.40 ± 0.56). The season did not affect the day of onset of luteal regression or its completion neither in animals with two-wave cycle nor with three- wave. The study concluded that the season had less or no impact on the growth and regression pattern of CL in CB cattle of Kerala.

Ultrasonography assisted estrus detection improves the submission rate in prostaglandin treated sub-estrus Murrah buffaloes

Sub-estrus is a condition in buffalo in which the ovarian picture and uterine changes suggest the presence of estrus and cyclicity, despite the absence of behavioural symptoms. The current study describes the effects of ultrasonography (USG)-aided estrus detection on submission and conception rate in sub-estrus Murrah buffaloes after a single shot of prostaglandin (PG) treatment. The study included 67 sub-estrus buffaloes between 2020 and 2021. The teaser bull was used to detect estrus, and the diameter of the pre-ovulatory follicle (POF) and corpus luteum (CL) was measured using transrectal USG. A single PG treatment induced behavioural estrus in 43.28% buffaloes (Gr. 1), while estrus were detected in 35.8% of sub-estrus buffaloes using sonographic examination (Gr. 2) that were otherwise remained undetected. The overall submission rate was 79.1 percent. The first-service conception rate was higher in Gr. 1 (55.2 vs. 33.3%), compared to Gr. 2. The CL diameter at pre-treatment was significantly larger in Gr. 1 buffaloes than in Gr.2 buffaloes. However, the POF diameter was comparable during induced estrus. Furthermore, the time elapsed between induction and breeding in both groups was comparable. Furthermore, the CL size at pre-treatment, POF size at estrus, and time elapsed to breeding had no effect on conception. Thus, the use of USG improves the submission rate in PG administered sub-estrus buffaloes, resulting in a 45.3% overall first service conception rate. However, breeding time must be optimised in order to improve the conception rate and efficient reproductive management in sub-estrus buffaloes in the field.

Effect of Dietary Rumen Protected Methionine on Postpartum Fertility Parameters in Multiparous Dairy Buffaloes (Bubalus bubalis)

Present study was planned to assess dietary supplementation of rumen protected methionine (RPM) peripartum on blood profile and postpartum reproductive outcome in 18 multiparous Murrah buffaloes. Animals were randomly assigned to 3 treatment groups of 6 each, and fed diets supplemented with RPM 20 g day-1 (Group 1); 10 g day-1 (Group 2), and standard control diet (Group 3). RPM feeding was introduced from day 30 prepartum till day 60 postpartum. Progesterone, estradiol, IGF-I, and biochemical parameters were estimated starting day 21 prepartum to day 57 postpartum. Size of dominant follicle and corpus luteum were assessed across the treatment days postpartum. Progesterone concentration varied from 0.32±0.06 to 3.85±0.44 ngml-1, 0.41±0.05 to 2.03±0.12 ngml-1, and 0.35±0.08 to 1.82±0.11 ngml-1 in Groups 1, 2 and 3, respectively. Corresponding estradiol levels ranged from 16.00±1.09 to 243.16±4.67 pgml-1, 13.16±0.60 to 228±5.06 pgml-1, and 13.66±0.66 to 218.9±4.36 pgml-1 and IGF-I from 77.83±8.81 to 149.50±4.69 ngml-1, 77.33±2.95 to 128.41±3.85 ngml-1, and 62.66±2.20 to 124.50±5.57 ngml-1 in Groups 1, 2 and 3, respectively. Variations in blood glucose, BUN and creatinine were observed across the days in all the treatment groups. Estrogen to progesterone (E/P) ratio varied (p&lt;0.05) among the treatment groups. Lower values of E/P in Group 1 were depictive of estrogen dominance, whereas higher E/P in Group 3 signified dominance of progesterone. Conception rates in Groups 1, 2 and 3 were 83.33%, 50.00% and 33.33%, respectively. Varying (p&lt;0.05) progesterone and estradiol levels were indicative of positive role of dietary RPM. Dietary RPM improved follicular structures and increased production and reproduction outcomes.