Rosuvastatin reduced brain parasite burden in a chronic toxoplasmosis in vivo model and influenced the neuropathological pattern of ME-49 strain.

This study evaluated the effects of rosuvastatin in vivo on toxoplasmosis chronic infection. Thirty-five Swiss mice were orally infected (ME-49 strain). After 50 days, the mice were separated into five groups: GI - non-infected, GII - infected, GIII - infected and treated with pyrimethamine and sulfadiazine (12.5 + 50 mg kg-1 body weight day-1), GIV and GV - infected and treated with rosuvastatin 10 and 40 mg kg-1 body weight day-1, respectively. After 21 days, we collected blood, liver, lungs, femoral biceps and brain were removed for Toxoplasma gondii DNA quantification by qPCR and histopathological analysis. GIV and GV did not present premature death or clinical changes, and the hepatic enzyme levels were lower compared to GI. Toxoplasma gondii DNA was detected mainly in brain and muscle, but the parasite load was significantly lower in GV compared to GII brains (P < 0.05). Histopathological changes were observed in brains, with T. gondii cysts as well as an inflammatory condition, including necrosis areas in GII and GIII. These data confirm active infection with tissue injury. This inflammatory condition was attenuated in the groups treated with rosuvastatin, especially R40 (GV). Our findings demonstrated the in vivo action of rosuvastatin in reducing cerebral parasitic load and indicate that this drug may interfere in chronic toxoplasmosis.

A diabetic foot ulcer treated with hydrogel and hyperbaric oxygen therapy: a case study.

This study reports on the case of an elderly patient, with diabetes, and a bullous wound on the left big toe that led to an amputation of the first and second left toes. The amputation was because of deep injury as it was not able to heal with a conventional treatment. After completing the normal treatment and the removal of a bacterial infection in the lesion, the patient underwent a treatment that was based on a hydrogel gel (0.9% saline solution) and hyperbaric oxygen therapy (HBOT). After 60 sessions of the therapy, almost complete closure of the wound was observed. There were no reports of discomfort or infection during the treatment. After seven months of treatment almost complete healing was observed with no infection. This treatment appears to be effective and should be recommended for the treatment of DFUs.

Short communication: Field fertility in Holstein bulls: Can type of breeding strategy (artificial insemination following estrus versus timed artificial insemination) alter service sire fertility?

The aim of this study was to compare pregnancy per artificial insemination (P/AI) from service sires used on artificial insemination after estrus detection (EAI) or timed artificial insemination (TAI) breedings. Confirmed artificial insemination outcome records from 3 national data centers were merged and used as a data source. Criteria edits were herd's overall P/AI within 20 and 60%, a minimum of 30 breedings reported per herd-year, service sires that were used in at least 10 different herds with no more than 40% of the breedings performed in a single herd, breeding records from lactating Holstein cows receiving their first to fifth postpartum breedings occurring within 45 to 375 d in milk, and cows with 1 to 5 lactations producing a minimum of 6,804 kg. Initially 1,142,859 breeding records were available for analysis. After editing, a subset of the data (n=857,539) was used to classify breeding codes into either EAI or TAI based on weekly insemination profile in each individual herd. The procedure HPMIXED of SAS was used and took into account effects of state, farm, cow identification, breeding month, year, parity, days in milk at breeding, and service sire. This model was used independently for the 2 types osires f breeding codes (EAI vs. TAI), and service sire P/AI rankings within each breeding code were performed for sires with >700 breedings (94 sires) and for with >1,000 breedings (n=56 sires) following both EAI and TAI. Correlation for service sire fertility rankings following EAI and TAI was performed with the PROC CORR of SAS. Service sire P/AI rankings produced with EAI and TAI were 0.81 (for sires with >700 breedings) and 0.84 (for sires with >1,000 breedings). In addition, important changes occurred in service sire P/AI ranking to EAI and TAI for sires with less than 10,000 recorded artificial inseminations. In conclusion, the type of breeding strategy (EAI or TAI) was associated with some changes in service sire P/AI ranking, but ranking changes declined as number of breedings per service sire increased. Future randomized studies need to explore whether changes in P/AI ranking to EAI versus TAI are due to specific semen characteristics.

Modifications to Ovsynch improve fertility during resynchronization: Evaluation of presynchronization with gonadotropin-releasing hormone 6 d before initiation of Ovsynch and addition of a second prostaglandin F2α treatment.

Lactating Holstein cows (n=897) were randomly assigned to a 2×2 factorial arrangement of treatments to compare the main effects of presynchronization with GnRH 6 d before beginning an Ovsynch protocol (±GnRH) and a second PGF2α treatment 24h after the first (1 vs. 2 PGF2α) on pregnancies per artificial insemination (P/AI). This resulted in the following 4 treatments: (1) an Ovsynch protocol (GPG, control); (2) presynchronization with GnRH followed by an Ovsynch protocol (GGPG); (3) an Ovsynch protocol with a second PGF2α treatment (GPPG); and (4) presynchronization with GnRH followed by an Ovsynch protocol with a second PGF2α treatment (GGPPG). All cows were submitted for first timed artificial insemination (TAI) using a Presynch Ovsynch protocol, and cows detected in estrus after the second PGF2α treatment of the Presynch portion of the protocol were inseminated and removed from the experiment. Nonpregnant cows were resynchronized using an Ovsynch protocol initiated 32±3 d after artificial insemination. Blood samples were collected at the first GnRH treatment (G1), at the PGF2α treatment (PGF), and at the last GnRH treatment (G2) of the Ovsynch protocol and were assayed for progesterone (P4) concentrations. Overall, P/AI tended to be greater for cows receiving a second PGF2α treatment compared with cows not receiving the second PGF2α treatment (40 and 37% for GGPPG and GPPG treatments, respectively, vs. 33 and 32% for GGPG and GPG treatments, respectively). Interestingly, treatment effects on P/AI were detected only for resynchronized cows receiving second and greater TAI, but not for cows receiving first TAI. Fewer cows presynchronized with GnRH had low (<0.5ng/mL) P4 at G1 than cows not presynchronized (13 vs. 25%), and P4 was greater at PGF2α for cows presynchronized with GnRH (4.4 vs. 4.0ng/mL). Cows receiving 2 PGF2α treatments had lower P4 at G2 than cows receiving 1 PGF2α treatment (0.15 vs. 0.35ng/mL). Differences in P4 at PGF2α were detected only for resynchronized cows and not for cows submitted for first TAI. We conclude that presynchronization with GnRH 6 d before beginning an Ovsynch protocol tended to increase P4 at the first GnRH treatment of an Ovsynch protocol, and that a second PGF2α treatment 24h after the first decreased P4 at TAI, thereby increasing P/AI in cows resynchronized for second and greater TAI.

Relationship between circulating anti-Müllerian hormone (AMH) and superovulatory response of high-producing dairy cows.

The main objective of this study was to evaluate the relationship between circulating anti-Müllerian hormone (AMH) and superovulatory response of dairy cows. Holstein cows (n=72) were milked twice daily and housed and fed individually in tiestalls. All animals were synchronized and flushed at 70±3 d in milk (DIM), near peak production (39.6kg/d). Blood samples for AMH analysis were collected at 3 different stages of a synchronized estrous cycle [at a random stage (40±3 DIM), proestrus (50±3 DIM), and diestrus (57±3 DIM)]. Body weights were measured weekly from calving until embryo collection. Statistical analyses were performed with Proc CORR and Proc GLIMMIX of SAS (SAS Institute Inc., Cary, NC). The 3 AMH samples from individual cows were correlated and not influenced by day of cycle. Surprisingly, AMH tended to be negatively correlated with body weight loss from calving to embryo collection (r=-0.22). More importantly, average AMH was highly associated (r=0.65) with superovulation response (number of corpora lutea on the day of the flush, CLN), total structures collected (r=0.48), and total transferable embryos (r=0.37), but not percentage of fertilized embryos (r=-0.20) or degenerate embryos (r=0.02). When cows were classified into quartiles (Q) of circulating AMH (Q1=0.01 to 82.6pg/mL; Q2=91.1 to 132.5pg/mL; Q3=135.3 to 183.8pg/mL; Q4=184.4 to 374.3pg/mL), we observed a >2-fold difference between first and fourth AMH quartiles in superovulation response (CLN: Q1=12.0±1.5; Q2=14.7±2.0; Q3=17.2±1.2; Q4=25.6±1.5) and embryo production. In conclusion, circulating AMH concentration was strongly associated with superovulation response, and evaluation of AMH could be used to identify cows with greater responses to superstimulation and thus improve efficiency of superovulation programs in dairy cows.

Relationships between fertility and postpartum changes in body condition and body weight in lactating dairy cows.

The relationship between energy status and fertility in dairy cattle was retrospectively analyzed by comparing fertility with body condition score (BCS) near artificial insemination (AI; experiment 1), early postpartum changes in BCS (experiment 2), and postpartum changes in body weight (BW; experiment 3). To reduce the effect of cyclicity status, all cows were synchronized with Double-Ovsynch protocol before timed AI. In experiment 1, BCS of lactating dairy cows (n = 1,103) was evaluated near AI. Most cows (93%) were cycling at initiation of the breeding Ovsynch protocol (first GnRH injection). A lower percentage pregnant to AI (P/AI) was found in cows with lower (≤ 2.50) versus higher (≥ 2.75) BCS (40.4 vs. 49.2%). In experiment 2, lactating dairy cows on 2 commercial dairies (n = 1,887) were divided by BCS change from calving until the third week postpartum. Overall, P/AI at 70-d pregnancy diagnosis differed dramatically by BCS change and was least for cows that lost BCS, intermediate for cows that maintained BCS, and greatest for cows that gained BCS [22.8% (180/789), 36.0% (243/675), and 78.3% (331/423), respectively]. Surprisingly, a difference existed between farms with BCS change dramatically affecting P/AI on one farm and no effect on the other farm. In experiment 3, lactating dairy cows (n = 71) had BW measured weekly from the first to ninth week postpartum and then had superovulation induced using a modified Double-Ovsynch protocol. Cows were divided into quartiles (Q) by percentage of BW change (Q1 = least change; Q4 = most change) from calving until the third week postpartum. No effect was detected of quartile on number of ovulations, total embryos collected, or percentage of oocytes that were fertilized; however, the percentage of fertilized oocytes that were transferable embryos was greater for cows in Q1, Q2, and Q3 than Q4 (83.8, 75.2, 82.6, and 53.2%, respectively). In addition, percentage of degenerated embryos was least for cows in Q1, Q2, and Q3 and greatest for Q4 (9.6, 14.5, 12.6, and 35.2% respectively). In conclusion, for cows synchronized with a Double-Ovsynch protocol, an effect of low BCS (≤ 2.50) near AI on fertility was detected, but change in BCS during the first 3 wk postpartum had a more profound effect on P/AI to first timed AI. This effect could be partially explained by the reduction in embryo quality and increase in degenerate embryos byd 7 after AI in cows that lost more BW from the first to third week postpartum.

Effects of treatment with human chorionic gonadotrophin or intravaginal progesterone-releasing device after AI on circulating progesterone concentrations in lactating dairy cows.

Adequate circulating progesterone (P4) is important for pregnancy. Lactating dairy cattle have lower circulating P4, particularly when smaller follicles are ovulated during timed AI protocols. The aim of the present study was to determine the supplementation strategy that resulted in P4 concentrations in lactating dairy cattle similar to those in heifers. Lactating Holstein cows (n=61) were synchronised using the Double-Ovsynch method and, on Day 5, were randomly assigned to receive no treatment (control), controlled internal drug release (CIDR), human chorionic gonadotrophin (hCG; 3300 IU) or CIDR+hCG. Heifers after normal oestrus were followed as controls (n=10). Profiles of circulating P4 concentrations were compared using repeated-measures ANOVA. Heifers had greater P4 concentrations than control cows at all times after Day 5 (P<0.0001). Cows receiving CIDR had lower P4 concentrations than heifers (P=0.0037) on Days 8-16. Treatment with hCG generally caused ovulation and resulted in circulating P4 concentrations greater than those in control lactating cows by 3 days after treatment (Day 8 after AI), but the treatment×time interaction (P=0.01) showed that cows treated with hCG generally had lower P4 concentrations than heifers. Supplementation with CIDR+hCG resulted in P4 concentration profiles similar to those in heifers. Thus, the use of CIDR and the production of an accessory corpus luteum with hCG elevates P4 concentrations in lactating cows to those seen in heifers. This information may be useful for designing future trials into P4 supplementation and fertility.

Effect of treatment with human chorionic gonadotropin on day 5 after timed artificial insemination on fertility of lactating dairy cows.

Reproductive management programs that synchronize ovulation can ovulate a smaller than normal follicle, potentially resulting in inadequate progesterone (P4) concentrations after artificial insemination (AI). Ovulation of the dominant follicle of the first follicular wave with human chorionic gonadotropin (hCG) treatment can produce an accessory corpus luteum and increase circulating P4 concentrations. This manuscript reports the results of 2 separate analyses that evaluated the effect of hCG treatment post-AI on fertility in lactating dairy cows. The first study used meta-analysis to combine the results from 10 different published studies that used hCG treatment on d 4 to 9 post-AI in lactating dairy cows. Overall, pregnancies per artificial insemination (P/AI) were increased 3.0% by hCG treatment post-AI [34% (752/2,213) vs. 37% (808/2,184); Control vs. hCG-treated, respectively]. The second study was a field research trial in which lactating Holstein cows (n=2,979) from 6 commercial dairy herds were stratified by parity and breeding number and then randomly assigned to one of 2 groups: control (no further treatment, n=1,519) or hCG [Chorulon i.m.: 2,000 IU (in 3 of the herds) or 3,300 IU (in 3 herds); n=1,460] on d 5 after a timed AI (ovulation synchronized with Ovsynch, Presynch-Ovsynch, or Double-Ovsynch). In a subset of cows, the hCG profile and P4 changes were determined. Treatment with hCG increased P4 (4.3 vs. 5.3 ng/mL on d 12). Pregnancies per AI were greater in cows treated with hCG (40.8%; 596/1,460) than control (37.3%; 566/1,519) cows. Interestingly, an interaction among treatment and parity was observed; primiparous cows had greater P/AI after hCG (49.7%; 266/535) than controls (39.5%; 215/544). In contrast, older cows receiving hCG (35.7%; 330/925) had similar P/AI to controls (36.0%; 351/975).Thus, targeted use of hCG on d 5 after TAI enhances fertility about 3.0% (based on meta-analysis) to 3.5% (based on our field trial). Surprisingly, this fertility-enhancing effect of hCG was very large in first-lactation cows but not observed in older cows in the field study. Future research is needed to confirm these intriguing results and to determine why older cows did not have improved fertility after hCG treatment.

Psychosocial factors associated with disability in patients with non-specific chronic low back pain: A cross-sectional study.

INTRODUCTION AND OBJECTIVES: Chronic low back pain is the main cause of disability worldwide, generating high costs for society. To evaluate the prevalence of disability in patients with non-specific chronic low back pain and associated factors, including the impacts of low back pain and psychosocial factors linked to kinesiophobia, catastrophism, anxiety, and depression. PATIENTS: A cross-sectional study was carried out with 108 adult individuals who had non-specific chronic low back pain. The patients answered previously validated questionnaires, namely the Brief Pain Inventory, the Roland-Morris Disability Questionnaire, the Pain Catastrophizing Scale, the Tampa Kinesiophobia Scale, and the Hospital Anxiety and Depression Scale. RESULTS: The prevalence of disability observed was 65.7%, with the mean disability score being 15.7±5.3 points in the Roland-Morris Disability Questionnaire. Although pain intensity and other domains of the Brief Pain Inventory, like anxiety, depression, and severe kinesiophobia were significant in the bivariate analyses, they were not associated with disability in the multivariate analysis. Only catastrophic thoughts (prevalence ratio [PR]=1.19; 95% confidence interval [CI]: 1.07-1.32), and the 'walking' domain (PR=1.08; 95% CI: 1.03-1.14) remained statistically associated with disability. CONCLUSION: Pain catastrophization and impact on gait were associated with disability in individuals with non-specific chronic low back pain. Motor control thoughts and behaviors during functional activities were considered to be relevant aspects for the better assessment and treatment of these patients.

Presynchronization with Double-Ovsynch improves fertility at first postpartum artificial insemination in lactating dairy cows.

The objective of this study was to compare circulating progesterone (P4) profiles and pregnancies per AI (P/AI) in lactating dairy cows bred by timed artificial insemination (TAI) following Ovsynch-56 after 2 different presynchronization protocols: Double-Ovsynch (DO) or Presynch-Ovsynch (PS). Our main hypothesis was that DO would increase fertility in primiparous cows, but not in multiparous cows. Within each herd (n=3), lactating dairy cows (n=1,687; 778 primiparous, 909 multiparous) were randomly assigned to DO [n=837; GnRH-7d-PGF(2α)-3d-GnRH-7d-Ovsynch-56 (GnRH-7d-PGF(2α)-56h-GnRH-16hTAI)] or PS (n=850; PGF(2α)-14d-PGF(2α)-12d-Ovsynch-56). In 1 herd, concentrations of P4 were determined at the first GnRH (GnRH1) of Ovsynch-56 and at d 11 after TAI (n=739). In all herds, pregnancy was diagnosed by palpation per rectum at 39 d. In 1 herd, the incidence of late embryo loss was determined at 74d, and data were available on P/AI at the subsequent second service. Presynchronization with DO reduced the percentage of animals with low P4 concentrations (<0.50 ng/mL) at GnRH1 of Ovsynch-56 (5.4 vs. 25.3%, DO vs. PS). A lesser percentage of both primiparous and multiparous cows treated with DO had low P4 concentrations at GnRH1 of Ovsynch-56 (3.3 vs. 19.7%, DO vs. PS primiparous; and 8.8 vs. 31.9%, DO vs. PS multiparous). Presynchronization with DO improved P/AI at the first postpartum service (46.3 vs. 38.2%, DO vs. PS). Statistically, a fertility improvement could be detected for primiparous cows treated with DO (52.5 vs. 42.3%, DO vs. PS, primiparous), but only a tendency could be detected in multiparous cows (40.3 vs. 34.3%, DO vs. PS, multiparous), consistent with our original hypothesis. Presynchronization treatment had no effect on the incidence of late embryo loss after first service (8.5 vs. 5.5%, DO vs. PS). A lower body condition score increased the percentage of cows with low P4 at GnRH1 of Ovsynch-56 and reduced fertility to the TAI. In addition, P4 concentration at d 11 after TAI was reduced by DO. The method of presynchronization at first service had no effect on P/AI at the subsequent second service (34.7 vs. 36.5%, DO vs. PS). Thus, presynchronization with DO induced cyclicity in most anovular cows and improved fertility compared with PS, suggesting that DO could be a useful reproductive management protocol for synchronizing first service in commercial dairy herds.

In vitro and in vivo analysis of fatty acid effects on metabolism of 17beta-estradiol and progesterone in dairy cows.

Some studies have reported improved reproductive performance with dietary fat supplementation. This study examined effects of fatty acids with different lengths, or desaturation, or both, on metabolism of estradiol (E2) and progesterone (P4) in bovine liver slice incubations (experiments 1 and 2) and in vivo (experiment 3). In experiment 1, effects of fatty acids C16:0 (palmitic acid), C16:1 (palmitoleic acid), C18:1 (oleic acid), and C18:3 (linolenic acid) were evaluated at 30, 100, and 300 microM on P4 and E2 metabolism in vitro. In experiment 2, stearic acid (C18:0) and C18:3 were evaluated in the same incubation conditions. In experiment 1, all of the fatty acids had some significant inhibitory effect on metabolism of P4, E2, or both (300 microM C16:0 on E2; 100 microM C16:1 on E2; 300 microM C16:1 on both P4 and E2; 300 microM C18:1 on P4; and 100 and 300 microM C18:3 on both P4 and E2). In experiment 2, C18:3 (100 and 300 microM) but not C18:0 decreased P4 and E2 metabolism. Overall, the most profound increase (approximately 60%) in half-life of P4 and E2 was observed with incubations of 300 microM C18:3 in both in vitro experiments. Based on these in vitro results, in experiment 3 linseed oil (rich in C18:3) was supplemented into the abomasum and acute effects on metabolism of E2 and P4 were evaluated. Cows (n=4) had endogenous E2 and P4 minimized (corpus luteum regressed, follicles aspirated) before receiving continuous intravenous infusion of E2 and P4 to analyze metabolic clearance rate for these hormones during abomasal infusion of saline (control) or 70 mL of linseed oil every 4h for 28h. Linseed oil infusion increased C18:3 in plasma by 46%; however, metabolic clearance rate for E2 and P4 were similar for control cows compared with linseed-treated cows. Thus, in vitro experiments indicated that E2 and P4 metabolism can be inhibited by high concentrations of C18:3. Nevertheless, in vivo, linseed oil did not acutely inhibit E2 and P4 metabolism, perhaps because insufficient C18:3 concentrations (increased to approximately 8 microM) were achieved. Further research is needed to determine the mechanism(s) of fatty acid inhibition of P4 and E2 metabolism and to discover practical methods to mimic this effect in vivo.

Hepatic mRNA expression of enzymes associated with progesterone metabolism and its impact on ovarian and endocrine responses in Nelore (Bos indicus) and Holstein (Bos taurus) heifers with differing feed intakes.

The aim of this study was to evaluate circulating progesterone concentration (P4), LH pulsatility and ovarian follicular dynamics in Nelore (B. indicus) and Holstein (B. taurus) heifers under high (HDMI) and low (LDMI) dry matter/energy intakes. In addition, the effects of dry matter/energy intake and breed on hepatic expression of six genes associated with P4 metabolism (AKR1C4, AKR1D1, CYP3A4, CYP2C19, SRD5A1, and SRD5A3) was evaluated. Heifers received an intravaginal P4 device (1 g), 2 mg of estradiol benzoate (EB) i.m. and 500 µg of PGF2α at the begging of the synchronization protocol (D0). Eight days later, the P4 device was removed and all heifers received 1 mg of EB 24h later. Regardless of dry matter/energy intake, the number of recruited follicles was greater in Nelore than in Holstein heifers. In contrast, the maximum diameter of the dominant follicle was greater in Holstein than in Nelore heifers. Circulating P4 concentrations were greater in Nelore than in Holstein from D2 to D9, and in heifers receiving LDMI than those receiving HDMI from D1 to D8 of hormonal protocol. In addition, Holstein heifers had greater LH pulsatility and area under the curve of LH peaks compared to Nelore heifers. However, no effects were observed for LH values between feed intake levels. Interestingly, Holstein heifers had higher expression of SRD5A1, AKR1C4, AKR1D1 than Nelore heifers; whereas, for Nelore heifers, only the expression of CYP3A4 was higher compared to Holstein heifers. In conclusion, there are important differences in the follicular dynamics, circulating P4 and LH pulsatility concentrations that need to be considered during synchronization protocols for Nelore and Holstein breeds. More importantly, these differences appear to be at least partially modulated by the level of feed intake and the contrasting enzyme system in the liver involved with P4 metabolism between these cattle breeds.

Effects of additional prostaglandin F2alpha and estradiol-17beta during Ovsynch in lactating dairy cows.

This study was designed to evaluate whether decreasing circulating progesterone (P4) or increasing circulating estradiol-17beta (E2) near the time of artificial insemination (AI) in an Ovsynch protocol would increase pregnancies per AI (P/AI) in lactating dairy cows. Six hundred nineteen lactating Holstein cows (n = 772 inseminations) received Ovsynch (GnRH-7 d-PGF(2alpha)-56 h-GnRH-16 h-timed AI). Cows were randomized in a 2 x 2 factorial experiment of 4 treatments to receive or not receive 25 mg of PGF(2alpha) 24 h after the standard PGF(2alpha) of Ovsynch, or 0.5 mg of E2 at the time of the final GnRH of Ovsynch, or both. Blood samples were collected 24 h after normal PGF(2alpha) and at final GnRH to evaluate circulating P4. Ovarian ultrasound was done at final GnRH to determine preovulatory follicle size. Ovulation was confirmed by ultrasound 5 d after AI. Treatment with additional PGF(2alpha) increased the percentage of cows that had complete luteal regression (95.6%) compared with control cows (84.6%). In contrast, additional PGF(2alpha) had no detectable effect on P/AI (control = 41.5% vs. + PGF(2alpha) = 44.7%). Supplementation with E2 increased expression of estrus (84.4 vs. 37.2%), but had no effect on overall fertility and even tended to have a negative effect on fertility in cows that ovulated to the second GnRH (control = 51.5% vs. +E2 = 44.0%). Thus, additional treatments with PGF(2alpha) or E2 during Ovsynch can be used to increase synchronization and expression of estrus during Ovsynch, although the lack of improvement in fertility makes these treatments unwarranted.

Ovulation and fertility response to commercially available GnRH products in lactating cows synchronized with the Double-Ovsynch protocol.

This study was designed to evaluate whether commonly used gonadorelin products that are commercially available in the United States results in comparable ovulation and pregnancy per AI (P/AI) in synchronized lactating dairy cows. A total of 1411 Holstein cows receiving a Double-Ovsynch protocol (DOV) for conducting the first postpartum AI were randomized to receive one of the following GnRH products throughout the Double-Ovsynch: 1) Cystorelin® (CYS, gonadorelin diacetate tetrahydrate, n = 484); 2) Factrel® (FAC, gonadorelin hydrochloride, n = 482) or; 3) Fertagyl® (FER, gonadorelin diacetate tetrahydrate, n = 515). A subgroup of cows (n = 487) received ovarian ultrasound exams and collection of blood samples for progesterone (P4) analysis. Proportion of cows ovulating following the 3rd GnRH of DOV tended (P = 0.07) to differ between GnRH salts (hydrochloride = 61.5% vs. diacetate = 72.7%) but was similar for GnRH products (FER = 74.1% vs. FAC = 61.5% vs. CYS = 72.2%). Interestingly, a logistic regression analyses that considered the circulating P4 at the time of GnRH treatment indicated lower ovulation responses to FAC compared to FER and CYS; although greater circulating P4 decreased ovulation response to all GnRH products. Results for P/AI at 60 d post-insemination differed between GnRH salts (P = 0.02) as well as GnRH products (FER = 47.8% vs. FAC = 42.0% vs. CYS = 49.8%; P = 0.04). In conclusion, fertility following use of the Double-Ovsynch was less following a hydrochloride-based GnRH product likely due to lesser ovulatory responses throughout the synchronization protocol.

A new presynchronization system (Double-Ovsynch) increases fertility at first postpartum timed AI in lactating dairy cows.

This study evaluated a novel presynchronization method, using Ovsynch prior to the Ovsynch-timed AI protocol (Double-Ovsynch) compared to Presynch-Ovsynch. Lactating Holstein (n=337) cows, were assigned to two treatment groups: (1) Presynch (n=180), two injections of PGF 14 d apart, followed by the Ovsynch-timed AI protocol 12 d later; (2) Double-Ovsynch (n=157), received GnRH, PGF 7 d later, and GnRH 3 d later, followed by the Ovsynch-timed AI protocol 7 d later. All cows received the same Ovsynch-timed AI protocol: GnRH (G1) at 68+/-3 DIM (mean+/-SEM), PGF 7 d later, GnRH (G2) 56h after PGF, and AI 16 to 20h later. Pregnancy was diagnosed 39-45 d after timed AI. Double-Ovsynch increased the pregnancies per AI (P/AI) compared to Presynch-Ovsynch (49.7% vs 41.7%, P=0.03). Surprisingly, Double-Ovsynch increased P/AI only in primiparous (65.2% vs 45.2%; P=0.02) and not multiparous (37.5% vs 39.3%) cows. In a subset of 87 cows, ovarian ultrasonography and progesterone (P4) measurements were performed at G1 and 7 d later. Double-Ovsynch decreased the percentage of cows with low P4 (<1ng/mL) at G1 (9.4% vs 33.3%) and increased the percentage of cows with high P4 (> or =3ng/mL) at PGF (78.1% vs 52.3%). Thus, presynchronization of cows with Double-Ovsynch increased fertility in primiparous cows compared to a standard Presynch protocol, perhaps due to induction of ovulation in non-cycling cows and improved synchronization of cycling cows. Future studies are needed, with a larger number of cows, to further test the hypothesis of higher fertility with Double-Ovsynch, and to elucidate the physiological mechanisms that underlie apparent changes in fertility with this protocol.

Effect of early luteolysis in progesterone-based timed AI protocols in Bos indicus, Bos indicus x Bos taurus, and Bos taurus heifers.

The objective of this study was to evaluate the effects of treatment with an intravaginal progesterone-releasing device (CIDR) and estradiol benzoate (EB) on follicular dynamics in Bos indicus (n=23), Bos taurus (n=25), and cross-bred (n=23) heifers. To assess the influence of reduced serum progesterone concentrations during 8 days of treatment with a progesterone-releasing device on follicular dynamics, half of the heifers received PGF at CIDR insertion (Day 0; 3 x 2 factorial design). Mean (+/-S.E.M.) serum progesterone concentrations during CIDR treatment varied (P<0.05) among genetic groups: B. indicus (5.4+/-0.1 ng/mL), B. taurus (3.3+/-0.0 ng/mL), and cross-bred (4.3+/-0.1 ng/mL). Maximum diameter of the dominant follicle (DF) was smaller (P<0.01) in B. indicus heifers (9.5+/-0.5 mm) than in cross-bred (12.3+/-0.4 mm) or B. taurus heifers (11.6+/-0.5 mm). B. indicus experienced lower (P<0.01) ovulation rate (39.1%) than did B. taurus (72.7%) and cross-bred (84.0%). Heifers treated with PGF on Day 0 had lower (P<0.05) serum progesterone concentrations during progesterone treatment. The PGF treatment on Day 0 increased (P<0.01) the diameter of the DF (11.9+/-0.4 mm vs. 10.5+/-0.4 mm). Moreover, greater (P=0.02) ovulation rates (78.8 vs. 54.0%) occurred in heifers treated with PGF on Day 0. In summary, B. indicus heifers had greater serum progesterone concentrations, smaller DF diameter, and a lower ovulation rate compared to B. taurus heifers. Prostaglandin treatment on the day of CIDR insertion reduced serum progesterone during treatment, and resulted in increased maximum DF diameter and ovulation rate.

Follicle deviation and ovulatory capacity in Bos indicus heifers.

The objectives of Experiment 1 were to determine the interval from ovulation to deviation, and diameter of the dominant follicle (DF) and largest subordinate follicle (SF) at deviation in Nelore (Bos indicus) heifers by two methods (observed and calculated). Heifers (n = 12) were examined ultrasonographically every 12 h from ovulation (Day 0) to Day 5. The time of deviation and diameter of the DF and largest SF at deviation did not differ (P>0.05) between observed and calculated methods. Overall, deviation occurred 2.5+/-0.2 d (mean +/- S.E.M.) after ovulation, and diameters for DF and largest SF at deviation were 6.2+/-0.2 and 5.9 +/- 0.2 mm, respectively. Experiment 2 was designed to determine the size at which the DF acquires ovulatory capacity in B. indicus heifers. Twenty-nine heifers were monitored every 24 h by ultrasonography, from ovulation until the DF reached diameters of 7.0-8.4 mm (n=9), 8.5-10.0 mm (n=10), or >10.0 mm (n=10). At that time, heifers were treated with 25 mg of pLH and monitored by ultrasonography every 12 h for 48 h. Ovulation occurred in 3 of 9, 8 of 10, and 9 of 10 heifers, respectively (P<0.05). In summary, there was no significant difference between observed and calculated methods of determining the beginning of follicle deviation. Deviation occurred 2.5 d after ovulation when the DF reached 6.2 mm, and ovulatory capacity was acquired by DF as small as 7.0 mm.

Induction of hyperlipidemia by intravenous infusion of tallow emulsion causes insulin resistance in Holstein cows.

The objective was to test whether the induction of elevated blood nonesterified fatty acids (NEFA) by i.v. infusion of a tallow emulsion altered glucose tolerance and responsiveness to insulin in Holstein cows. Six non-lactating, nongestating Holstein cows were assigned to a crossover design. One cow was excluded before initiation of the experiment because of complications from mastitis. Treatments consisted of 11-h i.v. infusions of saline (control) or a 20% (wt/vol) triacylglycerol (TG) emulsion derived from tallow (tallow) to elevate plasma NEFA. Each period consisted of two 11-h infusions (INF1 and INF2), separated by 1 d in which cows were not infused. Intravenous glucose tolerance tests (IVGTT) and insulin challenges (IC) were performed 8 h after initiation of INF1 and INF2, respectively. The infusion of treatments continued during the 3 h of sampling for IVGTT and IC. Cows were fed every 4 h at a rate to meet energy requirements for 5 d prior to each period, and every 2 h during the first 8 h of infusions. Infusion of tallow induced hyperlipidemia by increasing plasma NEFA (295 +/- 9 vs. 79 +/- 7 microEq/L), serum TG (41.0 +/- 6 vs. 11.4 +/- 4.4 mg/dL), and glycerol (0.81 +/- 0.09 vs. 0.23 +/- 0.1 mg/dL) concentrations during INF1. During INF2, tallow treatment increased plasma NEFA (347 vs. 139 +/- 18 microEq/L), serum TG (20.8 +/- 4.6 vs. 13.1 +/- 2.3 mg/dL), and glycerol (0.88 +/- 0.04 vs. 0.31 +/- 0.02 mg/dL) concentrations. Induction of hyperlipidemia impaired glucose clearance during IVGTT, despite the greater endogenous insulin response to the glucose infusion, leading to a lower insulin sensitivity index [0.29 vs. 1.88 +/- 0.31 x 10(-4) min(-1)/(microIU/mL)]. Accordingly, hyperlipidemia impaired glucose clearance during IC (1.58 vs. 2.72 %/min), reflecting lower responsiveness to insulin. These data show that induction of hyperlipidemia causes insulin resistance in Holstein cows by impairing both sensitivity and maximum responsiveness to insulin. The induction of insulin resistance by TG, NEFA, or both may increase the availability of glucogenic nutrients to the periparturient dairy cow. Yet excessive elevation of NEFA may potentially lead adipocytes to become more insulin resistant, further increasing plasma NEFA concentration and the risk of metabolic disorders.

Supplementation with estradiol-17beta before the last gonadotropin-releasing hormone injection of the Ovsynch protocol in lactating dairy cows.

The aim of this study was to determine whether an increase in circulating estrogen concentrations would increase percentage pregnant per artificial insemination (PP/AI) in a timed AI protocol in high-producing lactating dairy cows. We analyzed only cows having a synchronized ovulation to the last GnRH of the Ovsynch protocol (867/1,084). The control group (n = 420) received Ovsynch (GnRH--7 d--PGF(2alpha)--56 h--GnRH--16 h--timed AI). The treatment group (n = 447) had the same timed AI protocol with the addition of 1 mg of estradiol-17beta (E2) at 8 h before the second GnRH injection. Ovarian ultrasound and blood samples were taken just before E2 treatment of both groups. In a subset of cows (n = 563), pressure-activated estrus detection devices were used to assess expression of estrus at 48 to 72 h after PGF(2alpha) treatment. Ovulation was confirmed by ultrasound 7 d after timed AI. Treatment with E2 increased expression of estrus but overall PP/AI did not differ between E2 and control cows. There was an interaction between treatment and expression of estrus such that PP/AI was greater in E2-treated cows that showed estrus than in E2-treated or control cows that did not show estrus and tended to be greater than control cows that showed estrus. There was evidence for a treatment by ovulatory follicle size interaction on PP/AI. Supplementation with E2 improved PP/AI in cows ovulating medium (15 to 19 mm) but not smaller or larger follicles. The E2 treatment also tended to improve PP/AI in primiparous cows with low (< or =2.5) body condition score, and in cows at first postpartum service compared with Ovsynch alone. In conclusion, any improvements in PP/AI because of E2 treatment during a timed AI protocol appear to depend on expression of estrus, parity, body condition score, and size of ovulatory follicle.

Impact of phase of the estrous cycle and season on LH surge profile and fertility in dairy cows treated with different GnRH analogs (gonadorelin vs. buserelin).

Our aim was to assess the GnRH-induced LH surge profile in dairy cows receiving two GnRH products (gonadorelin vs buserelin) given at proestrus or diestrus phase and to investigate whether season could alter LH surge profile in dairy cows. In Experiment 1, dairy cows at 108.2 ± 2.3 DIM, producing 41.5 ± 0.3 kg/day were randomized to receive, during proestrus and diestrus: Ovarelin® i.m. (OVA; n = 56; 100 mg of gonadorelin diacetate tetrahydrate; Ceva Animal Health, France) or Receptal® i.m. (REC; n = 52; 10 mcg of buserelin diacetate; MSD, Germany). In Experiment 1, blood samples were collected at hour 0 (just before GnRH treatment) at 30min, 1 h and then hourly until 5 h post-GnRH. In Experiment 2, cows were synchronized with a modified G-6-G protocol and randomized to receive either OVA or REC throughout the synchronization program. In Experiment 1, peak LH concentrations (ng/mL) were not affected by type of GnRH (OVA = 6.2 ± 0.4 vs REC = 6.7 ± 0.4; P = 0.37) or season (Cool = 6.8 ± 0.4 vs Warm = 6.1 ± 0.4; P = 0.22), and there were no interactions between GnRH type and phase of the estrous cycle or season. Interestingly, the area under the curve (AUC) of LH release (ng/ml*time) was significantly lower during warmer months (Cool = 20.3 ± 1.2 vs Warm = 16.9 ± 1.1; P = 0.04). As expected, LH peak was affected by phase of the cycle (proestrus = 8.2 ± 0.4 vs diestrus = 4.7 ± 0.4; P < 0.01). Ovarelin caused LH concentrations to increase faster, reaching highest concentration sooner (h) than REC (1.5 ± 0.1 vs 2.3 ± 0.1; P < 0.01). As a result, cows receiving OVA had greater circulating LH concentrations (ng/mL) at 1 h after GnRH treatment than cows receiving REC (P < 0.01). In contrast, cows treated with REC had longer (P = 0.01) intervals from peak until return to nadir. In Experiment 2, pregnancy per AI (P/AI) was similar for cows receiving either GnRH product during the synchronization protocol, with no detectable interactions between GnRH type and season. In conclusion, phase of the estrous cycle had a great impact on the GnRH-induced LH surge profile and cows during warm season had reduced AUC. Additionally, type of GnRH did not influence LH surge profile and P/AI in synchronized cows. Regardless of GnRH type, strategies to avoid heat stress and excessively high levels of circulating P4 near the time of GnRH treatment might help improve LH release profile in dairy cows, and ultimately increase P/AI.