Effects of long-acting injectable progesterone supplementation at early dioestrus on pregnancy maintenance in beef and dairy recipient cattle.

We tested in the present study the hypothesis that supplementation with long-acting P4 (iP4) at different times of the initial dioestrus improves pregnancy rates in dairy and beef recipients submitted to fixed-time embryo transfer (FTET). Recipients from commercial farms had their oestrous cycle synchronized with an E2/P4-based protocol in three experiments (Exp. 1 to 3). In Exp. 1, dairy heifers (n = 76) and cows (n = 104) were randomly assigned to two experimental groups: the control group (n = 89) and the iP4D4 group (n = 91). For Exps. 2 and 3, suckled beef recipients were used. In Exp. 2, recipients were assigned to two experimental groups: Control group (n = 147) and iP4D7 group (n = 144); whereas in Exp. 3, recipients were randomly assigned to three experimental groups: Control group (n = 85), iP4-D4 group (n = 86) and iP4D7 group (n = 81). Recipients in the iP4D4 and iP4-D7 groups received an i.m. administration of 150 mg iP4, on D4 or D7 (D0 was the day of expected oestrus). On D7, all recipients were evaluated by transrectal ultrasonography and those that had a CL received a fresh or vitrified in vitro-produced embryo. In Exp. 2 and 3, the CL area was also determined by ultrasonography at the time of FTET. The pregnancy diagnosis was performed at 30 days in Exp. 1, 57 days in Exp. 2, and between 40 and 72 days of pregnancy in Exp. 3. In Exp. 1, the pregnancy rate did not differ (p > .1) between the Control group (38.2% [34/89]) and iP4D4 group (49.5% [45/91]); yet, a parity effect indicated a greater (p < .05) pregnancy rate in heifers (57.9% [44/76]) than cows (30.8% [32/104]). In Exp. 2, the pregnancy rate was greater (p < .05) in the iP4D7 group (45.0% [65/144]) than in the Control group (34.0% [50/147]). Also, a greater (p = .08) pregnancy rate was observed for recipients with a small CL (≤2.75 cm2 ) that were treated with iP4 on the day of FTET than the control recipients (46.4% [32/69] vs. 32.6% [28/86]). In Exp. 3, no significant effects (p > .1) of the treatment group or CL size were detected on pregnancy rates at days 30 and 60. In conclusion, the beneficial effects of iP4 supplementation at early dioestrus on pregnancy maintenance may vary according to the experimental conditions, but its use at the time of FTET can be used as an alternative to enhance the fertility of beef recipients in challenging conditions in commercial herds.

Effects of source of supplementary trace minerals in pre- and postpartum diets on reproductive biology and performance in dairy cows.

Our objectives were to evaluate the effects of complete replacement of inorganic salts of trace minerals (STM) with organic trace minerals (OTM) in both pre- and postpartum diets on ovarian dynamics, estrous behavior measured by sensors, preimplantation conceptus development, and reproductive performance in dairy cows. Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 d before their expected calving. Pre- and postpartum diets were formulated to meet 100% of recommended levels of each trace mineral in both treatments, taking into consideration both basal and supplemental levels. The final target concentrations of Co, Cu, Mn, Se, and Zn were, respectively, 0.25, 13.7, 40.0, 0.3, and 40.0 mg/kg in the prepartum diet, and 0.25, 15.7, 40.0, 0.3, and 63.0 mg/kg in the postpartum diet. The STM group was supplemented with Co, Cu, Mn, and Zn sulfates and sodium selenite, while the OTM group was supplemented with Co, Cu, Mn, and Zn proteinates and selenized yeast. Treatments continued until 156 d in milk (DIM) and were assigned to individual cows using automatic feeding gates. Starting at 21 DIM, ultrasonography examinations of the ovaries were performed weekly to determine the presence of a corpus luteum and postpartum resumption of ovarian cyclicity. Cows were presynchronized with 2 injections of PGF2α at 42 and 56 DIM. Estrous behavior was monitored using electronic activity tags that indirectly measured walking activity. Cows detected in estrus after the second PGF2α were inseminated, and those not detected in estrus by 67 DIM were enrolled in a synchronization program. Cows that returned to estrus after artificial insemination (AI) were reinseminated. Pregnancy diagnosis was performed 33 d after AI, and nonpregnant cows were resynchronized. Transcript expression of interferon-stimulated genes in peripheral blood leukocytes was performed in a subgroup of cows (STM, n = 67; OTM, n = 73) on d 19 after AI. A different subgroup of cows (28 STM, 29 OTM) received uterine flushing 15 d after AI for recovery of conceptuses and uterine fluid for analyses of transcriptomics and metabolomics, respectively. In addition, dominant follicle diameter, luteal size and blood flow, and concentration of progesterone in plasma were measured on d 0, 7, and 15 relative to AI. After flushing, PGF2α was given and the dominant follicle was aspirated 2 d later to measure the concentration of trace minerals by mass spectrometry. Estrous behavior, size of the dominant follicle and corpus luteum, concentration of progesterone, time to pregnancy, and proportion of cows pregnant by 100 d of the breeding period did not differ between treatments. A greater proportion of cows supplemented with OTM had a corpus luteum detected before presynchronization (64.3 vs. 75.2%), and primiparous cows supplemented with OTM tended to resume cyclicity earlier than their STM counterparts. Cows supplemented with OTM had a greater concentration of Cu in follicular fluid than cows supplemented with STM (0.89 vs. 0.77 µg/mL, respectively). In pregnant multiparous cows, expression of receptor transporter protein 4 in peripheral blood leukocytes was 42% greater in the OTM group. Conceptuses of the 2 treatments had 589 differentially expressed transcripts, with many indicating advanced conceptus elongation and greater transcript expression of selenoproteins in the OTM group. In pregnant cows, 24 metabolites were more abundant in the uterine fluid of OTM, including spermidine, sucrose, and cholesterol. In conclusion, replacing STM with OTM caused modest improvements to resumption of ovarian cyclicity and important changes in preimplantation conceptus development, but it did not alter conception risk and pregnancy rate.

High ß-carotene concentration in plasma enhances cyclic progesterone production in nonpregnant Japanese Black cows.

ß-Carotene is an essential nutrient in cattle reproduction. The objective of this study was to evaluate the effect of ß-carotene supplementation on ovarian activities throughout the estrous cycle in nonpregnant Japanese Black cows. The estrous cycles of eight nonpregnant Japanese Black cows were synchronized using a double synch protocol, and the cows were divided into two groups. The cows in the ß-carotene (BC) group received supplementation with 1000 mg/day ß-carotene for 46 days including the synchronization period. The cows in the control (C) group did not receive ß-carotene supplementation. The results showed that ß-carotene supplementation at 1000 mg/day was sufficient to maintain a high plasma ß-carotene concentration and increase the plasma retinol concentration and that ß-carotene supplementation had no significant effects on the dominant follicle diameter, total number of estrus behaviors, or length of the estrous cycle. In contrast, the areas under the P4 concentration curves in the BC group were higher than those obtained for the C group. In conclusion, a high plasma ß-carotene concentration in Japanese Black cows promotes P4 production in the luteal phase of the estrous cycle and total P4 production throughout the estrous cycle without changing the length of the estrous cycle.

Effect of lowering blood cortisol level along with progesterone priming on intensifying the secondary symptoms of oestrus in Murrah buffaloes during the hot summer months.

The present study sought to intensify oestrus symptoms in heat-stressed pre-pubertal Murrah buffalo heifers. The first experiment aimed at lowering the blood cortisol level. Twenty pre-pubertal buffalo heifers approximately 36-40 months of age were randomly allocated to four groups of five buffaloes. Group Gly received 100 ml glycerol orally for 8 days (day 0 is the start of treatments), group Gly-E received intra-muscular injections of 500 mg tocopherol (vitamin E activity) and 150 mg sodium selenite on alternate days (four treatments) in addition to treatments received by group Gly, group Gly-E + B-Ch received intra-muscular injections of vitamin B-complex and choline daily for 8 days in addition to the treatments received by group Gly-E. The control group Co-1 did not received any treatments. Blood cortisol and glucose level was measured on day 7 post-treatment. The second experiment sought to test the effect of lowering the blood cortisol level and progesterone priming on the intensity of oestrus symptoms in heat-stressed pre-pubertal buffalo heifers. Eighty buffaloes were allocated into four groups of twenty buffaloes. P4 group received intra-vaginal progesterone CIDR for 5 days (day 0 is the day of start of treatment). Gly-E group received the same treatment as in the first experiment for 7 days (day 0-6) and P4 + Gly-E received the combination of P4 and Gly-E groups. The control group Co-2 did not receive any treatments; however, on day 6, all groups received intra-muscular injection of 2 mg estradiol benzoate. The buffaloes were graded for oestrus symptoms on the basis of mucus discharge (A-scanty and B-copious), vulvar redness (slightly pink and moist-A and deep red and moist-B), ferning (nil or poor-A and good with arborization-B) and cellularity of cervical mucus (Type A goblet cells with round nucleus and abundant cytoplasm and Type B goblet cells with cylindrical nucleus and scanty cytoplasm). The blood glucose level (mean ± SEM) of Gly group on day 7 of treatment in experiment 1 was 58.3 ± 0.4 mg/dl that was significantly greater than Co-1 (52.4 ± 0.4 mg/dl), Gly-E (53.5 ± 0.8 mg/dl) and Gly-E + B-Ch (52.7 ± 0.6 mg/dl) groups; however, the difference was found to be non-significant among Co-1, Gly-E and Gly-E + B-Ch groups. The cortisol level (mean ± SEM) on day 7 in groups Gly (11.4 ± 0.6 ng/ml), Gly-E (8.1 ± 0.5 ng/ml) and Gly-E + B-Ch (7.5 ± 0.4 ng/ml) was significantly lower than groups Co-1 (15.5 ± 0.3 ng/ml), though the difference between groups Gly-E and Gly-E + B-Ch was non-significant and the level in group Gly-E significantly lower than Gly. Thus, the combination of vitamin E and selenium along with glycerol had the best effect in the reduction of blood cortisol level in heat-stressed buffaloes. In the second experiment the blood estradiol level on day 7 in all groups was around 40 pg/ml. Cortisol reduction (group Gly-E) improved oestrus symptoms (mucus discharge and ferning) compared to control, but when compared to group P4 showed non-significant difference with respect to mucus discharge, vulvar redness and ferning of cervical mucus. However, when cortisol reduction treatments were combined with progesterone priming (group P4 + Gly-E) oestrus symptoms were improved with respect to mucus discharge and ferning thus, combination treatment had synergistic effect. This effect was also observed with cellularity of cervical mucus, where combination treatment group P4 + Gly-E produced cervical mucus with significantly lower percentage of Type B cells compared to group P4 and group Gly-E. Thus, administration glycerol and vitamin E selenium combination reduces blood cortisol level and along with progesterone priming can be effective to improve the oestrus symptoms of buffaloes during the hot summer months.

Increasing vitamin D levels to improve fertilization rates in cattle.

Recently, interest in supplementing vitamin D (Vit D) to improve aspects of health, mainly in human fertility, has emerged. Still, supplementation of Vit D above the minimum required levels has yet to be explored in cattle despite evidence for Vit D receptors in reproductive tissues. The objective of this study was to establish if a dose-response relationship exists between Vit D exposure and success of in vitro production (IVP) of embryos and, if acute supplementation of Vit D improves pregnancy rates during timed artificial insemination (TAI) of dairy cows. Cumulus-oocyte complexes (COCs) were obtained from ovaries acquired from a local abattoir and cultured in five different IVP treatments from three separate collections (Control, 50, 100, 150, and 200 ng/mL of 1,25(OH)2D3; n = 20-30 COCs/group). In Experiment 2, dairy breed cows (n = 100) were synchronized for TAI with the PresynchOvsynch protocol. Cows received 150,000 IU of Vit D (n = 48) or castor oil as control (n = 53) along with gonadotropin-releasing hormone (GnRH) 24 h before TAI. Serum samples were collected before and 24 h after treatment. A small cohort of cows (n = 4) received the same treatments in two separate cycles and follicular fluid (FF) was collected after 24 h for calcidiol (25OHD) analyses. Increased concentrations of Vit D resulted in decreased rates of maturation of COC (150 and 200 ng/mL vs. control and 50 ng/mL; P = 0.01). Supplementation with 50 ng/mL resulted in greater numbers of early blastocyst and blastocyst stage embryos (P < 0.009). Pregnancy at first breeding did not differ (P = 0.13) between groups, but serum 25OHD increased in treated females after 24 h (P = 0.002). The FF 25OHD levels were reflective of serum levels, however, the observed increase in the treatment cycle (P = 0.04) was parallel to an overall increase in serum 25OHD during the entire second cycle, likely due to increased environmental sunlight exposure (March, control vs. May, treatment). A similar increase in the serum 25OHD in the lactating commercial herd maintained in covered housing was not observed, although experiments were conducted during a similar timeframe. This herd had levels of 25OHD near the low end of sufficiency according to National Research Council (NRC) guidelines. We conclude mild Vitamin D supplementation with concentrations at the higher end of NRC guidelines can improve maturation rates of recovered COCs. However, longer term supplementation may be needed to appreciate any benefits on fertility.

Vitamin D is an important hormone that among other things, contributes to bone health, immunity, and reproduction. Recently, research has linked vitamin D to fertility in other species (primates), and therefore the objectives of the current research were to determine if mild supplementation with Vitamin D impacted fertility in female cattle. A dose-dependent relationship was detected between concentrations of vitamin D and embryo development. The concentration of 50 ng/mL of vitamin D appeared to be beneficial to early embryogenesis. Studies in dairy-breed females indicated serum levels of vitamin D correlated well with intrafollicular levels in the periovulatory follicle. Finally, a fertility trial investigated if a single dose of vitamin D improves fertility when administered before artificial insemination in cattle. There were no detectable benefits to this brief supplementation with vitamin D on measures of fertility in this group. It is concluded supplementation with vitamin D improves embryo development in vitro, but brief supplementation did not impact pregnancy success. Longer-term supplementation with vitamin D may be needed to appreciate any measurable benefits on fertility.

Progesterone supplementation to improve fertility of selected subgroups of lactating cows during the summer and fall.

One major cause of low fertility of cows in the summer is progesterone deficiency. We found that insertion of a controlled intravaginal drug-releasing (CIDR) device containing progesterone after artificial insemination (AI) increases pregnancy per AI (P/AI) in cows with uterine disease and low body condition score after calving. Here, we treated only these two subgroups, during the summer and autumn. Control (n = 191 AI) and treatment (n = 230 AI) cows were inseminated at estrus and the treated group received a CIDR device on day 5 post-AI, for 14 days. Overall analysis of data during the summer and autumn indicated no significant differences between treatment and control groups. Analysis of the summer data only indicated a significant effect of treatment: P/AI was higher in CIDR-treated vs. control groups (34.2% vs. 19.3%; p < .038). Results indicated a 15% increase in P/AI during the summer for CIDR-treated cows in subgroups that had responded positively to the progesterone treatment.

Mineral supplementation (injectable) improved reproductive performance in Holstein cows managed in a warm summer environment.

Sustainability of dairy production depends largely on reproductive efficiency that is affected by heat stress due to high ambient temperature and humidity during summer. Supplementation of minerals has been proposed as a management strategy to minimize adverse impact of heat stress on fertility. The objective of this study was to determine the effects of an injectable mineral supplement (Fosfosan) containing selenium (Se), copper (Cu), potassium (K), magnesium (Mg) and phosphorus (P) on the ovarian structures, reproductive hormones and conception rate of heat-stressed Holstein cows. Sixteen cows were assigned during summer to one of two treatments, a control group (CON; n = 8) and a mineral-supplemented group (SUP; n = 8). Ambient temperature and relative humidity records were collected and processed to estimate the temperature-humidity index (THI), which confirmed a heat-stressed environment during the study (avg. THI = 79.4). Cows were subjected to a fixed-time artificial insemination (FTAI) program using the CIDR-Synch synchronization protocol. Traits indicative of ovarian activity were recorded during and after this protocol, as well as serum concentrations of reproductive hormones. Pregnancy diagnosis was made 28 and 35 d after FTAI. A completely randomized block design with repeated measures over time was performed to study ovarian functional structures and its hormonal profiles. Correlations and regressions were estimated to study relationships between ovarian structures and related hormones. Mineral supplementation did not increase follicular diameter or follicular populations (p > .05), yet tended to increase corpus luteum diameter (p < .10), and it enhanced (p < .01) oestrogen and progesterone serum concentrations and improved (p < .05) cow's conception rate. Diameter of dominant follicles and corpus luteum was correlated (p < .05) with oestrogen and progesterone levels, respectively, but only in mineral-treated cows. Two additional dairy herds were evaluated to confirm that mineral supplementation improved conception rate during the heat stress period (objective 2). Cows from dairy 1 received FTAI during winter (n = 401) and summer (n = 240), whereas cows from dairy 2 were bred after natural detected oestrus during winter (n = 558) and summer (n = 314). Conception rates were higher (p < .05) in winter than summer and they improved (p < .05) with mineral supplementation, but only in cows managed during summer. In conclusion, supplementation of minerals enhanced hormonal secretion from ovarian structures and improved conception rate in Holstein cows exposed to summer heat stress.

Stair-step strategy and immunomodulatory feed ingredient supplementation for grazing heat-stressed Bos indicus-influenced beef heifers.

On day 0 of years 1 and 2, 64 Brangus crossbred heifers per year were stratified by initial body weight (BW) and age (mean = 257 ± 20 kg and 271 ± 22 d) and allocated into 16 bahiagrass (Paspalum notatum) pastures (4 heifers per pasture per yr). Treatments were randomly allotted to pastures in a 2 × 2 factorial arrangement of treatments (4 pastures per treatment per yr). Treatments consisted of concentrate dry matter (DM) supplementation at 1.50% of BW from days 0 to 100 (CON) or concentrate DM supplementation at 1.05% of BW from days 0 to 49 and 1.95% of BW from days 50 to 100 (SST). Then, each respective supplementation strategy was added or not with immunomodulatory feed ingredients from days 0 to 100 (OMN; 4 g/45 kg of BW). Heifers were assigned to an estrus synchronization protocol from days 100 to 114. Heifers detected in estrus from days 111 to 114 were inseminated (AI) 12 h after estrus detection. Heifers not detected in estrus were timed AI on day 114. All heifers were exposed to Angus bulls from days 120 to 210 (1 bull per pasture). Effects of supplementation strategy × OMN inclusion × hour were detected (P < 0.0001) only for intravaginal temperature from days 26 to 30, which were the least (P ≤ 0.03) for SST heifers offered OMN supplementation and did not differ (P ≥ 0.17) among all remaining treatments from 0830 to 1600 hours. Effects of supplementation strategy × OMN inclusion and OMN inclusion were not detected (P ≥ 0.12) for any variable, except for the percentage of heifers detected in estrus, which was greater (P = 0.01) for heifers supplemented with vs. without OMN. Total concentrate DM offered from days 0 to 100 and heifer BW on days 0 and 56 did not differ (P ≥ 0.49) between CON and SST heifers, but SST heifers were heavier (P ≤ 0.01) on days 100 and 210 compared with CON heifers. Body surface temperature on day 25 and plasma IGF-1 concentrations on day 75 were greater (P ≤ 0.04) for SST vs. CON heifers. Percentage of pubertal heifers, heifers detected in estrus, and pregnancy to AI did not differ (P = 0.36) between SST and CON heifers but the final pregnancy percentage was greater (P = 0.04) for SST vs. CON heifers. Thus, OMN supplementation decreased the intravaginal temperature of SST heifers but failed to improve their growth and reproduction, whereas the SST strategy improved body thermoregulation, growth, and final pregnancy percentage of heat-stressed Bos indicus-influenced beef heifers compared with a constant concentrate supplementation strategy.

In Bos taurus beef heifers, altering the timing of body weight (BW) growth pattern either reduced feed costs without decreasing reproduction or enhanced reproduction without increasing feed costs. Moreover, supplementation of OmniGen-AF (OMN, a patented immunomodulatory feed ingredient) decreased internal body temperature in dairy and beef B. taurus cattle, with variable impacts on growth and reproduction. Combining both nutritional strategies for Bos indicus-beef heifers developed under heat stress conditions of tropical and subtropical environments has not been reported in the literature yet and was the main objective of the present study. For 100 d before the breeding season, heifers received either a constant supplementation amount or stair-step (SST) supplementation strategy (50 d of low followed by 50 d of high supplement amount), with or without OMN inclusion. Overall, OMN supplementation alleviated the internal body temperature of heifers but did not improve their growth and reproduction, whereas the SST strategy increased BW gain and final pregnancy percentage of B. indicus-influenced beef heifers under heat stress conditions.

Parenteral Copper Administration at the Beginning of a Fixed-Time Artificial Insemination Protocol in Beef Cattle: Effect on Ovarian Function and Pregnancy Rates.

The aim of this study was to evaluate the association between plasma copper (Cu) concentration and ovarian function during a fixed-time artificial insemination (FTAI) protocol and the effect of parenteral Cu administration (100 mg) at the start of such protocol (day 0) on area of preovulatory follicle (APF); area of corpus luteum (ACL), plasma estradiol (E2), and progesterone (P4) concentrations; CL blood flow (CLBF); and pregnancy rate in beef heifers and cows. In cows, plasma Cu concentration on days 0 and 7 correlated positively with APF. Copper administration increased plasma Cu concentration and decreased APF and plasma E2 concentration (day 9), without modifying ACL, plasma P4 concentration, and CLBF (day 16) in cows. Pregnancy rate was higher in Cu-supplemented cattle on day 41 after FTAI as compared with controls (58.76 and 45.28%, respectively). In conclusion, Cu administration at the beginning of the FTAI protocol increased pregnancy rate in beef heifers and cows, modifying APF and plasma E2 concentration in the latter.

Improved reproductive performance achieved in tropical dairy cows by dietary beta-carotene supplementation.

Dairy farming in tropical climates is challenging as heat stress can impair reproduction in cows. Previous studies have demonstrated the beneficial effects of beta-carotene supplementation on bovine reproductive performance. This study was performed in Thailand, where the temperature-humidity index (THI) during the experimental periods was measured to range from 78.4 to 86.1. Lactating Holstein cows classified as repeat breeders (previous artificial insemination [AI] failures) were randomly assigned into two treatments, control treatment (T1; received placebo, n = 200) and test treatment (T2; received 400 mg/h/day of beta-carotene, n = 200). All cows were subjected to a protocol for synchronization of ovulation and timed artificial insemination (TAI). The day of the 1st ovulation synchronized protocol was defined as day 0, and the total experimental period was 160 days. Daily placebo or beta-carotene supplements were given orally on day 0 and each subsequent day of the experiment. Diagnosis of pregnancy was performed using ultrasound on day 30 after insemination. Non-pregnant cows were subjected to further ovulation synchronizations (maximum of four) and TAI over a period of 160 days. Milk samples were collected every ten days throughout the experiment. The samples were analyzed for beta-carotene concentration, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. The pregnancies per AI of the cows in T2 were significantly greater than that of T1 from the 2nd to 4th TAI. During the entire experimental period, the pregnancies in T2 were significantly greater than that of T1. Cox's proportional hazards regression model data indicated a 44% greater probability of pregnancy for cows receiving beta-carotene. The concentrations of milk beta-carotene in T2 were significantly greater than T1 from the 2nd to 4th TAI. Significantly greater SOD and GPx activities were observed in T2 than T1, suggesting a reduction of oxidative stress in cows treated with beta-carotene. Dietary supplementation with beta-carotene thus improves the reproductive performance of repeat breeders exposed to heat stress, possibly by reducing oxidative stress.

Progesterone supplementation in Holstein heifers subjected to cooling and timed AI during summer: physiological and reproductive variables and thyroid hormone concentrations.

Our aim was to evaluate the effects of progesterone supplementation after fixed-time artificial insemination (FTAI) on physiological and reproductive variables and serum thyroid hormone concentrations of cooled Holstein heifers during a hot summer season. Sixty-nine Holstein heifers were randomly assigned to three treatments: (1) heifers under visual estrus detection and inseminated according to AM-PM rule (n = 23; control (C)), (2) heifers subjected to FTAI after estrus synchronization using a CIDR insert (n = 24; FTAI group), and (3) heifers treated as the FTAI group plus progesterone supplementation between the day 4 and 14 post-insemination with a reused CIDR device (n = 22; FTAI+SP4 group). All heifers were cooled daily with misting and fans. Physiological variables were measured; likewise, blood samples were collected to determine serum progesterone, thyroxine, and triiodothyronine concentrations. Both respiration rate and rectal temperature were similar among treatments. Conception rate was greater (P < 0.05) in C (65.2%) and FTAI+SP4 (59.1%) heifers than in FTAI heifers (33.3%). Serum triiodothyronine and progesterone concentrations of FTAI+SP4 heifers were similar to those of C heifers but greater (P < 0.05) than those of FTAI heifers. In conclusion, progesterone supplementation post-insemination increased conception rate and serum progesterone concentrations without affecting thermoregulation capacity in Holstein heifers subjected to FTAI and cooling during a hot summer season.

Progesterone dose during synchronization treatment alters luteinizing hormone receptor and steroidogenic enzyme mRNA abundances in granulosa cells of Nellore heifers.

The objective was to investigate effects of progesterone (P4) dose on abundance of luteinizing hormone receptor (LHCGR), aromatase (CYP19A1), 3ß-hydroxysteroid dehydrogenase (HSD3B1), and other steroidogenic mRNA transcripts in granulosa cells from dominant follicles. Nellore heifers were assigned to one of six groups: new, first-use controlled internal drug release device (CIDR1) inserted for 5 days (Large-P4-dose-D5; n = 7) or 6 days (Large-P4-dose-D6; n = 8), prostaglandin (PG)F2α administered on D0 and 1 previously-used CIDR (CIDR3) inserted for 5 days (Small- P4-dose-D5; n = 8) or 6 days (Small-P4-dose-D6; n = 8), CIDR1 inserted on D0 and removed plus PGF2α on D5 (Large-P4-dose-proestrus (PE); n = 7), and CIDR3 and PGF2α on D0 and 1, CIDR3 removed plus PGF2α on D5 (Small-P4-dose-PE; n = 7). Duration of P4 treatment (D5 compared to D6) affected abundances of CYP19A1 mRNA transcripts, with there being greater abundances on D6 than D5 (P ≤ 0.05). Heifers treated with the large dose of P4 had a smaller dominant follicle, less serum and intra-follicular estradiol (E2) concentrations (P ≤ 0.05) and lesser LHCGR, CYP19A1, and HSD3B1 transcript abundances (P ≤ 0.05). Heifers treated to induce PE had a larger follicle diameter (P = 0.09), greater intra-follicular E2 concentrations and larger abundances of CYP19A1 mRNA transcript (P ≤ 0.05) than heifers of the D6 group. Overall, treatment with larger doses of P4 resulted in lesser abundances of LHCGR, HSD3B1, and CYP19A1 mRNA transcripts; thus, potentially leading to development of smaller dominant follicles and lesser E2 concentrations.

Effects of equine chorionic gonadotropin administered via the Baihui acupoint on follicular ovarian dynamics and the luteal function of cattle during an ovulation synchronization treatment regimen for fixed-time artificial insemination.

Objectives were to evaluate effects of a smaller than typically used dose of equine chorionic gonadotropin (eCG) during a fixed-time artificial insemination (FTAI) treatment regimen. Transrectal ultrasonic (US) examinations were conducted on dairy cows on Day 0 (D0) and the treatment regimen was initiated with administrations of an intravaginal progesterone (P4) implant, estradiol benzoate (im), and prostaglandin F2α (PGF2α; im). On D8, the P4 implant was removed and PGF2α and estradiol cypionate were administered to all animals. Subsequently, cows were randomly assigned to three groups and eCG was administered to Groups 1, 2, and 3 in doses of 300 (im); 100 (im); and 100 (Baihui acupoint) IUs, respectively. The B-mode and power-flow US cineloops were performed to assess follicular dynamics and evaluate various morphological and vascular characteristics of the corpus luteum. Blood samples were collected to quantify serum P4 concentrations. There were no differences between the ovulation synchronization treatment regimens for all follicular dynamic variables tested; however, cows in Group 3 differed from Group 2 having a larger follicle diameter (FD) on D10 (P = 0.06) and larger preovulatory FD (P = 0.09), as well as a blood perfusion area of the dominant follicle wall on D8 (P = 0.07). There were no differences in responses to the ovulation synchronization treatment regimens for the luteal variables evaluated subsequent to ovulation. In conclusion, the Baihui acupoint was effective as an alternative route for eCG dose reduction when FTAI treatment regimens were imposed without detrimentally affecting values for reproductive variables.

Effects of Flaxseed-rich Diet on Reproductive Performance in Estrous-synchronized Baluchi Ewes.

The purpose of this study was to compare the effects of using different levels of flaxseed in diets on the reproductive performance of estrous-synchronized Baluchi ewes (para 3). Diets contained either basal diet (control) or different levels of extruded flaxseed (2%, 5%, 7%, 10%, and 12%) and were fed from lambing to 60 days after lambing. The ewe estrus cycles were synchronized using controlled internal drug release (CIDR) for 14 days starting from day 16 of fat supplementation. The rams were introduced 24 h after CIDR removal. The ewes fed control diets had the highest mean dry matter intake (1,800&plusmn;35 g) which was declined with the increase of flaxseed levels. The experimental diets exerted no effects of urea concentration in blood plasma. However, plasma glucose concentration was lower (p &lt;0.05) in the ewes fed the control diet and 2% flaxseed, compared to those in other groups. Nonetheless, there was no difference among the ewes fed 5%, 7%, 10%, and 12% flaxseed in terms of plasma glucose concentrations (p &lt;0.05). The ewes fed 2% flaxseed had the highest level of plasma triglyceride concentration among other groups. In addition, the control group had the lowest level of plasma total cholesterol and low-density lipoproteins concentration in comparison to other groups (p &lt;0.05). However, plasma nonesterified fatty acids and &beta;-hydroxybutyrate concentrations were similar among the groups (P&gt;0.05). The mean interval between CIDR removal and the exhibition of estrus ranged from 30 to 40 h with the shortest interval being recorded in the ewes fed 12% flaxseed (p &lt;0.05). The control group had the lowest number of follicles on estrus day among other groups (p &lt;0.05). Furthermore, the ewes fed 10% and 12% flaxseed had the highest ovulation, pregnancy, and lambing rates, compared to other groups (p &lt;0.05). In conclusion, the findings revealed that feeding the ewes with 10% and 12% flaxseed resulted in the improvement of reproductive performance.

A randomized controlled clinical trial on the effect of acupuncture therapy in dairy cows affected by pyometra.

Pyometra (PYO) is a reproductive disease characterized by the accumulation of purulent or mucopurulent material within the uterine lumen, in the presence of an active corpus luteum (CL). As the CL continues secreting progesterone, PYO would develop following endometritis. Due to prohibited use of artificial luteolytic hormones in US certified organic dairies, conventional therapies consisting of administration of prostaglandin F2α, are not applicable. The objective of this study was to evaluate the efficacy of two acupuncture procedures on the treatment of persistent CL in cows with PYO. We hypothesized that acupuncture would reduce CL diameter and serum progesterone (P4) concentrations, leading to regression of PYO. Holstein cows with PYO, at an USDA certified organic dairy farm in Northern Colorado, were enrolled in a randomized controlled clinical trial and assigned to 1 of 3 treatments: (1) control pyometra (CP; no treatment; n = 17); (2) electroacupuncture (EAP; n = 15); and (3) laser acupuncture (LAP; n = 15). Each cow received three 9-min (EAP) or 20-min (LAP) acupuncture sessions in alternate days. All study cows had blood samples collected for determination of serum progesterone concentration at d0, and at d2, d4, d11, d18, and d25 after first treatment. The ovaries were scanned by transrectal ultrasonography at -3d, d0, d2, d4, d11, and d18 to determine the diameter of the CL. The effect of treatment in the outcome variables was evaluated by ANOVA and by repeated measures analyses, accounting for baseline data (CL diameter and progesterone serum concentration). Average ± SE change in CL diameter from d0 to d18 were 0.94 ± 1.0 mm, 0 ± 1.0 mm, and - 0.33 ± 1.0 mm for CP, EAP, and LAP, respectively. The repeated measures analysis indicated no significant differences for CL diameter among groups. None of the study cows had serum progesterone values <1 ng/ml by the end of the monitoring period (d25) and average ± SE change from d0 to d25 were - 4.0 ± 1.97 ng/ml, -0.76 ± 2.1 ng/ml, and 3.24 ± 1.9 ng/ml for CP, EAP, and LAP, respectively. The repeated measures analysis indicated no significant differences for serum progesterone concentrations among groups. On farm cow records reviewed 150 d after treatment indicated that 2 cows in EAP and 1 cow in LAP conceived 38 d, 68 d, and 38 d, after treatment completion. In conclusion, acupuncture was not an effective treatment for persistent CL in cows with PYO, during the monitoring period.

Effect of progesterone supplementation in a resynchronization protocol on follicular dynamics and pregnancy success.

The objective of this study was to evaluate the necessity of a controlled internal drug releasing device (CIDR) in a fixed-time AI resynchronization protocol as well as to compare a commercially available blood pregnancy test with transrectal ultrasonography for Day 28 pregnancy detection. Over a two-year period, beef cows and heifers from twelve herds were inseminated using the 7-day CO-Synch + CIDR protocol. On Day 21 following the first insemination, the protocol was repeated, with animals receiving either a CIDR or no CIDR. Pregnancy status (AI1) was determined on Day 28 by both transrectal ultrasonography and the IDEXX Rapid Visual Pregnancy Test. Non-pregnant animals by both methods (CIDR: n = 190 cows, n = 228 heifers; no CIDR: n = 185 cows, n = 223 heifers) received an injection of Prostaglandin F2alpha and were inseminated at the appropriate time or bred following detection of estrus. Corpora lutea (CL) number and largest follicle diameter were recorded on a subset of non-pregnant animals (CIDR: n = 66 cows, n = 46 heifers; no CIDR: n = 76 cows, n = 41 heifers) at time of pregnancy diagnosis on Day 28. Final pregnancy status was determined a minimum of 31 days following the second AI (AI2). The GLIMMIX procedure of SAS was utilized for estrus and pregnancy data; while the MIXED procedure was utilized for analyses of CL number and largest follicle diameter. There was no effect (P ≥ 0.55) of treatment on AI1 pregnancy, AI2 pregnancy, or overall pregnancy rates. The presence of a CIDR during the resynchronization increased (P < 0.001) estrus expression prior to AI2. There was an effect of treatment by age on AI2 pregnancy (P < 0.01); heifers that received a CIDR had greater AI2 pregnancy rates than heifers that did not receive a CIDR (P = 0.04), but there was no difference between cows with and without a CIDR. Treatment had no effect (P > 0.10) on embryonic loss (between the first and second pregnancy diagnosis), CL number, or follicle diameter. Although, there was a tendency for the interaction of treatment by age on follicle size (P = 0.07), with cows having larger follicles than heifers in the no CIDR group but not the CIDR group. In conclusion, use of a CIDR in this resynchronization protocol increased estrus expression, increased AI2 pregnancy for heifers, but did not improve pregnancies in cows, and did not influence overall pregnancy or embryonic loss.

Supplementation frequency and amount modulate postweaning growth and reproductive performance of Bos indicus-influenced beef heifers.

This 2-yr study evaluated the growth and puberty attainment of Bos indicus-influenced beef heifers offered 2 different postweaning concentrate supplementation amounts and delivery frequencies. On day 0 of each year, 64 Brangus crossbred heifers were stratified by initial body weight (BW) and age (mean = 244 ± 22 kg; 314 ± 17 d) and assigned into 1 of 16 bahiagrass pastures (4 heifers/pasture/yr). Treatments were randomly assigned to pastures in a 2 × 2 factorial design (4 pastures/treatment/yr) and consisted of concentrate dry matter (DM) supplementation at 1.25% or 1.75% of BW which were offered either daily (7×) or 3 times weekly (3×) for 168 d. On day 56 of each year, heifers were assigned to an estrus synchronization protocol consisting of intravaginal controlled internal drug release (CIDR) insertion on day 56, CIDR removal on day 70, i.m. injection of 25 mg of prostaglandin F2α (PGF2α) on day 86, and i.m. injection of 100 µg of gonadotropin-releasing hormone and timed-AI at 66 h after PGF2α injection (day 89). Heifers were exposed to Angus bulls from day 89 to 168 (1 bull/pasture). Pregnancy diagnosis was assessed on day 213 of each year. Supplementation amount × frequency effects were not detected (P ≥ 0.12) for any variable, except for plasma concentrations of glucose (P = 0.10) and urea nitrogen (PUN; P = 0.01). Herbage mass, herbage allowance, and nutritive value did not differ (P ≥ 0.12) among treatments. Increasing supplementation DM amount from 1.25% to 1.75% of BW increased (P ≤ 0.05) plasma concentrations of insulin-like growth factor 1 (IGF-1), overall average daily gain (ADG), final BW, percentage of pubertal heifers on day 89, pregnancy and calving percentages, and percentage of heifers calving within the first 21 d of the calving season. However, reducing the supplementation frequency from daily to 3× weekly, regardless of supplementation amount, did not impact overall pregnancy and calving percentages (P ≥ 0.42), but caused (P ≤ 0.05) fluctuations in plasma concentrations of insulin and IGF-1 and decreased (P ≤ 0.03) overall ADG, final BW, puberty attainment on days 56, 89, and 168, and percentage of heifers calving during the first 21 d of the calving season. Hence, increasing the supplement DM amount did not prevent the negative effects of reducing the frequency of supplementation (3× vs. 7× weekly) on growth and reproduction of replacement Bos indicus-influenced beef heifers.

Effect of dietary n-3 polyunsaturated fatty acid supplementation on the expression of genes involved in progesterone biosynthesis in the corpus luteum of goat (Capra hircus).

Emerging evidence indicates that dietary n-3 polyunsaturated fatty acids (PUFA) alter the fatty acid composition of corpus luteum (CL) and directly affect the luteal function in the cow, which is independent of the inhibitory effect on the endometrial PGF2α production. The present study, thus, investigated the effects of n-3 PUFA rich fish oil (FO) supplementation on the transcriptional modulation of genes involved in the biosynthesis of progesterone (P4 ) in the CL collected during the luteolytic phase of oestrous cycle in the goat. On the day of synchronized oestrus, goats (n = 6/group) were fed an isocaloric diet supplemented with either FO or palm oil (PO). The dose of oil supplementation was 0.6 mlkg-1 body weight, and the duration was 55-57 days. The FO provided 156 mgkg-1 body weight of n-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The CL was collected by laparotomy on day 16 post-oestrus, and the relative abundance of P450 side-chain cleaving enzyme, steroid acute regulatory protein (StAR) and 3ß-hydroxy steroid dehydrogenase (3ß-HSD) genes was quantitated by real-time PCR. The results indicated that the dietary FO significantly upregulated the expression of 3ß-HSD by 1.13-fold and downregulated StAR by ~2-fold as compared to PO group (p < .05). It is concluded that dietary FO differently affected the expression of genes involved in P4 synthesis in the CL during the luteolytic window of the oestrous cycle in the goat.

Artificial lactation by exogenous hormone treatment in non-pregnant sows.

This study aimed to determine if lactation can be induced by exogenous hormonal treatment in non-pregnant sows. In experiment 1, pseudopregnant animals were divided into four groups and given: 1) 5 mg of estradiol dipropionate (EDP) 5 days before (n = 4), 2) 5 mg of EDP 10 days before (n = 3), 3) 10 mg of EDP 5 days before (n = 3) or 4) 10 mg of EDP 10 days (n = 3) before PGF2α treatment. Artificial lactation was induced in seven pseudopregnant sows (53.8%) by exogenous hormonal treatment. There was no significant effect of either an increased EDP dosage or interval from the EDP treatment to PGF2α treatment on the induction rate of artificial lactation. In experiment 2, milk samples were collected from artificial lactating and natural lactating sows (n = 6). IgG and IgA levels in the milk collected from both groups were significantly associated with time during the experimental period. Milk IgG levels 24 h after PGF2α treatment in artificial lactating sows were higher than those in the colostrum of lactating sows. In experiment 3, hormonal profiles in pseudopregnant sows with (n = 3) or without (n = 3) EDP treatment were determined. There was a significant difference in estradiol-17ß levels on days 8, 7 and 5 before PGF2α treatment between groups. Progesterone and prolactin concentrations did not differ between groups. The present study revealed for the first time that lactation could be induced by exogenous hormonal treatment in non-pregnant sows and that the milk collected from these sows contained high immunoglobulin levels.

The effect of pre-breeding vitamin E and selenium injection on reproductive performance, antioxidant status, and progesterone concentration in estrus-synchronized Mehraban ewes.

The present study was conducted to assess the effects of pre-breeding vitamin E and selenium (ESe) injections on the reproductive performance, antioxidant status, and serum progesterone (P4) concentration in estrus-synchronized Mehraban ewes. During the breeding season, 38 ewes (3-4 years) were divided into two groups (n = 18), and the synchronization of estrus was achieved by intravaginal insertion of 0.3 g progesterone CIDR device for 13 days followed by 350 IU eCG at CIDR withdrawal. Ewes were kept under pasture conditions and exposed to Mehraban rams 48 h following CIDR withdrawal. The experimental treatments were control and ESe injection. The ESe group was received three intramuscular (5 mL) injections of Ese (0.5 mg/mL of selenium as sodium selenite and 50 IU vitamin E as DL-α- tocopheryl) once every 2 weeks. Specifically, Ese was administered at 2 weeks before CIDR insertion, at the times of CIDR insertion and CIDR withdrawal. Fertility, prolificacy, lambing rate, and birth weight were recorded after parturition. Blood samples were collected at CIDR insertion, CIDR withdrawal, 5, 10, and 15 days after ram exposure. Fertility, prolificacy, lambing rate, and birth weight did not improve by Ese treatment, but viability of lambs was higher in ESe than control (P < 0.05). Serum total antioxidant capacity at day 5 and P4 at day 10 after ram exposure was higher in ESe than control (P < 0.05). In conclusion, sheep breeders can use ESe at CIDR insertion and withdrawal times to potentiate antioxidant status and progesterone profile of estrus-synchronized Mehraban ewes.