Browsing by Author "Guenther, Jerry N."
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Item Comparison of gonadorelin products in lactating dairy cows: Efficacy based on induction of ovulation of an accessory follicle and circulating luteinizing hormone profiles(Elsevier Science, 2009-07-15) Souza, Alex H.; Cunha, Arcelina Pacheco; Silva, Eder Pereira; Ayres, Henderson; Guenther, Jerry N.; Wiltbank, Milo C.; Gümen, Ahmet; Uludağ Üniversitesi/Veteriner Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; AAH-1406-2021; 6602393069This study evaluated whether the four gonadorelin products that are commercially available in the United States produce comparable ovulation responses in lactating cows. Dairy cows at 7 d after last gonadotropin-releasing hormone (GnRH) treatment of Ovsynch (Day 7), with a corpus luteum (CL) >= 15 mm and at least one follicle >= 10 mm, were evaluated for response to GnRH treatment. Selected cows were randomized to receive (100 mu g; im): (1) Cystorelin (n = 146): (2) Factrel (n = 132): (3) Fertagyl (n = 140); or (4) Ovacyst (n = 140). On Day 14, cows were examined for Ovulation by detection of an accessory CL. Circulating luteinizing hormone (LH) concentrations were also evaluated in some cows after treatment with 100 mu g (n = 10 per group) or 50 mu g (n = 5 per group) GnRH. Statistical analyses were performed with the procedures MIXED and GLIMMIX of the SAS program. Percentage of cows ovulating differed (P < 0.01) among groups, with that for Factrel being lower (55.3%) than that for Cystorelin (76.7%), Fertagyl (73.6%), or Ovacyst (85.0%), There was no effect of batch, parity, or follicle size on ovulation response. but increasing body condition score decreased Ovulation response. There was a much greater LH release in cows treated with 100 mu g than in those treated with 50 mu g, but there were no detectable differences among products in time to LH peak, peak LH concentration, or area under the LH curve and no treatment effects nor treatment by time interactions on circulating LH profile. Thus, ovulation response to Factrel on Day 7 of the cycle was lower than that for other commercial GnRH products, although a definitive mechanism for this difference between products was not demonstrated.Item Effect of feed restriction on reproductive and metabolic hormones in dairy cows(Elsevier, 2014-02) Ferraretto, Luiz F.; Hackbart, Katherine S.; Nascimento, Aníbal Ballarotti; Dalla Costa, F.; Bender, Robb W.; Guenther, Jerry N.; Shaver, Randy Duncan; Wiltbank, Milo Charles; Gençoğlu, Hıdır; Uludağ Üniversitesi/Veterinerlik Fakültesi/Zootekni ve Hayvan Besleme Bölümü.; 15753357900The objective of this trial was to evaluate the effects of feed restriction (FR) on serum glucose, nonesterified fatty acids, progesterone (P4), insulin, and milk production in dairy cows. Eight multiparous Holstein cows, 114 +/- 14 d pregnant and 685 +/- 39 kg of body weight, were randomly assigned to a replicated 4 x 4 Latin square design with 14-d periods. During the first 8 d of each period, cows in all treatments were fed for ad libitum feed intake. Beginning on d 9 of each period, cows received 1 of 4 treatments: ad libitum (AL), 25% feed restriction (25FR), 50% feed restriction (50FR), and 50% of TMR replaced with wheat straw (50ST). Daily feed allowance was divided into 3 equal portions allocated every 8 h with jugular blood samples collected immediately before each feeding through d 14. In addition, on d 12 of each period, blood samples were collected before and at 60, 120, 180, 240, 300, 360, 420, and 480 mm after morning feeding. The conventional total mixed ration and total mixed ration with straw averaged 15.1 and 10.8%, 32.1 and 50.5%, and 26.8 and 17.0% for concentrations of crude protein, neutral detergent fiber, and starch, respectively. Cows that were feed and energy restricted had reduced dry matter intake, net energy for lactation intake, circulating glucose concentrations, and milk production, but greater body weight and body condition score losses than AL cows. Circulating concentrations of insulin were lower for cows fed 50FR (8.27 p,mu IU/mL) and 50ST (6.24 mu IU/mL) compared with cows fed AL (16.65 mu IU/mL) and 25FR (11.16 p,mu IU/mL). Furthermore, the greatest plasma nonesterified fatty acids concentration was observed for 50ST (647.7 mu Eq/L), followed by 50FR (357.5 mu Eq/L), 25FR (225.3 mu Eq/L), and AL (156.3 mu Eq/L). In addition, serum P4 concentration was lower for cows fed AL than cows fed 50ST and 25FR. Thus, FR reduced circulating glucose and insulin but increased P4 concentration, changes that may be positive in reproductive management programs.Item Managing the dominant follicle in high-producing dairy cows(Nottingham University, 2010) Wiltbank, Milo Charles; Filho, Roberto Sartori; Vasconcelos, José Luiz Moraes; Nascimento, Aníbal Ballarotti; Souza, Alexandre H.; Cunha, A. P.; Sangsritavong, Siwat; Guenther, Jerry N.; Lopez, Hernando; Pursley, James Richard; Gümen, Ahmet; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; AAH-1406-2021; 6602393069Reduced reproductive efficiency has been reported in high-producing dairy cows. Sources of reproductive inefficiency include decreased expression of estrus, increased diameter of the ovulatory follicle and reduced fertility when cows are inseminated after estrus, increased incidence of double ovulation and twinning, and increased pregnancy loss. To overcome some of these inefficiencies, reproductive management programs have been developed that synchronize ovulation and enable effective timed artificial insemination (AI) of lactating dairy cows. Effective regulation of the corpus luteum (CL), follicles, and hormonal environment are critical for optimizing these programs. Recent programs, such as the 5-day CIDR program, Double-Ovsynch, G-6-G, and estradiol benzoate-CIDR programs were designed to more effectively control one or more physiological events. These events include synchronization of a new follicular wave at the beginning of the program, optimization of the circulating progesterone (P4) concentrations and duration of follicular dominance, optimized reductions in P4 and increases in circulating estradiol (E2) concentrations during the preovulatory period, and tightly synchronized ovulation of a follicle of optimal size and fertility for implementation of timed AI. The success of these programs has been remarkable, although there is substantial variability in effectiveness due to environmental, management, nutritional, genetic, and disease factors as well as potential variability in some aspects of reproductive physiology among commercial dairy farms. Future programs will optimize the reproductive physiology while simplifying the protocol implementation and also match specific reproductive management protocols to specific farms and even specific cows (for example primiparous vs. multiparous).Item Managing the dominant follicle in lactating dairy cows(Elsevier Science, 2011-12) Wiltbank, Milo Charles; Filho, Roberto Sartori; Herlihy, Mary M.; Vasconcelos, José Luiz Moraes; Nascimento, Aníbal Ballarotti; Souza, Alexandre H.; Ayres, Henderson; Cunha, A. P.; Guenther, Jerry N.; Keskin, Abdülkadir; Gümen, Ahmet; Uludağ Üniversitesi/Tıp Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; AAH-1406-2021; AAH-3831-2021; 24473229800; 6602393069Reproductive efficiency is not optimal in high-producing dairy cows. Although many aspects of ovarian follicular growth in cows are similar to those observed in heifers, there are numerous specific differences in follicular development that may be linked with changes in reproductive physiology in high-producing lactating dairy cows. These include: I) reduced circulating estradiol (E2) concentrations near estrus, 2) ovulation of follicles that are larger than the optimal size, 3) increased double ovulation and twinning, and 4) increased incidence of anovulation with a distinctive pattern of follicle growth in anovular dairy cows. The first three changes become more dramatic as milk production increases, although anovulation has not generally been associated with level of milk production. To overcome reproductive inefficiencies in dairy cows, reproductive management programs have been developed to synchronize ovulation and enable the use of timed AI in lactating dairy cows. Effective regulation of the CL, follicles, and hormonal environment during each part of the protocol is critical for optimizing these programs. This review discusses the distinct aspects of follicular development in lactating dairy cows and the methodologies that have been utilized in the past two decades in order to manage the dominant follicle during synchronization of ovulation and timed AI programs.Item Presynchronization with Double-Ovsynch improves fertility at first postpartum artificial insemination in lactating dairy cows(Elsevier Science, 2012-12) Herlihy, Mary M.; Giordano, Julio O.; Souza, Alex H.; Ayres, Henderson; Ferreira, Roberta M.; Nascimento, Anibal B.; Guenther, Jerry N.; Gaska, Jerry M.; Kacuba, S. J.; Crowe, Mark A.; Butler, Stephen T.; Wiltbank, Milo C.; Keskin, Abdulkadir; Uludağ Üniversitesi/Veteriner Fakültesi/Doğum ve Jinekoloji Ana Bilim Dalı.; AAH-3831-2021; 24473229800The objective of this study was to compare circulating progesterone (P4) profiles and pregnancies per AT (P/AI) in lactating dairy cows bred by timed artificial insemination (TAT) 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(2 alpha)-3d-GnRH-7d-Ovsynch-56 (GnRH-7d-PGF(2 alpha)-56h-GnRH-16hTAI)] or PS (n = 850; PGF(2 alpha)-14d-PGF(2 alpha)-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 74 d, 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.Item Ultrasonographic evaluation of endometrial thickness near timed AI as a predictor of fertility in high-producing dairy cows(Elsevier, 2011-03-01) Souza, Alexandre H; Silva, Eduardo P.B.; Cunha, Arcelina Pacheco; Ayres, Henderson; Brusveen, D. J.; Guenther, Jerry N.; Wiltbank, Milo Charles; Gümen, Ahmet; Uludağ Üniversitesi/Veterinerlik Fakültesi/Veteriner Doğum ve Jinekoloji Anabilim Dalı.; AAH-1406-2021; 6602393069The objectives were to evaluate changes in endometrial thickness (ET) near the time of a synchronized ovulation and to assess the relationship of ET and fertility in lactating Holstein cows, with or without estrogen supplementation near timed ovulation. In Experiment 1, eight cows were examined with transrectal ultrasonography, once daily for 5 d, starting concurrent with PGF(2 alpha) (PGF) treatment during an Ovsynch protocol (GnRH - 7d - PGF - 72h - GnRH). The ET increased rapidly after PGF (from similar to 7 to similar to 9.5 mm), remained > 9 mm for the next 2 d, then decreased to similar to 8 and 7.4 mm, 1 and 2 d, respectively, after the second GnRH. In Experiment 2,642 cows (total of 758 breedings) were subjected to an Ovsynch protocol (GnRH - 7d - PGF - 56h - GnRH - 16h - timed AI); cows received either no further treatment (Ovsynch) or 1 mg of estradiol-17 beta im 8 h before the second GnRH (Ovsynch + E2). For both uterine horns, ET was measured (similar to 2 cm from the internal uterine body bifurcation) before E2 treatment (48 h after PGF). In cows with ET <= 8 mm vs > 8 mm, rates of ovulation were 86.0% (n = 136) vs 98.1% (n = 472; P < 0.01), respectively, and percentage pregnant per AT (P/AI) were 26.7% (n = 146) vs 42.7% (n = 524; P < 0.01). Treatment with E2 increased P/AI in cows with lower ET (Ovsynch + E2 = 37.0% vs Ovsynch = 23.3%; P = 0.07), but did not significantly improve P/AI in cows with ET > 8 mm (Ovsynch + E2 = 43.4% vs Ovsynch = 42.1%). In conclusion, a single ultrasonographic evaluation of ET in Holstein cows 48 h after PGF treatment in an Ovsynch program was a good predictor of ovulation failure and pregnancy success. Perhaps poor fertility in cows with reduced ET was low peripheral E2 concentrations near AI, poor P4 priming, or luteolysis failure during timed AI procedures.