Two synchronization protocols were tested for lactating dairy cows and heifers. Nulliparous dairy heifers (13 to 23 mo; n = 155) and primiparous and multiparous dairy cows (60 to 289 d postpartum; n = 310) were assigned randomly to two treatments. Controls received 25 mg of PGF2 alpha and were artificially inseminated according to the a.m.-p.m. rule following detected estrus. All controls that were not detected in estrus were injected with 25 mg of PGF2 alpha at 14-d intervals until artificial insemination (AI) at a detected estrus or until timed AI at 72 to 80 h after a third sequential injection of PGF2 alpha. Treated cows and heifers received a protocol that used GnRH and PGF2 alpha to synchronize ovulation (Ovsynch). Cows and heifers that were treated with Ovsynch were injected i.m. with 100 micrograms of GnRH at a random stage of the estrous cycle. Seven days later, cows and heifers in this group received 25 mg of PGF2 alpha followed by a second injection of 100 micrograms of GnRH 30 to 36 h later. Subsequently, the treated cows and heifers received AI 16 to 20 h after the second injection of GnRH. Pregnancy rates per AI were similar (38.9% vs. 37.8%) for control cows and cows treated with the Ovsynch protocol, respectively. However, pregnancy rate per AI was greater for control heifers (74.4%) than for heifers treated with Ovsynch (35.1%). Evaluation of serum progesterone concentrations at each hormonal injection indicated that the first injection of GnRH synchronized luteal function of lactating dairy cows but not of heifers. In summary, one fixed-time AI at a synchronized ovulation provided similar pregnancy rates per AI as did AI following the a.m-p.m. rule after estrus had been induced by PGF2 alpha in lactating cows, but the fixed-time AI was not effective for heifers because of the lack of synchronization.

Our objective was to determine whether progesterone (P4) supplementation during an Ovsynch protocol would enhance fertility in lactating dairy cows. Lactating dairy cows (n = 634) at 6 locations were assigned randomly within lactation number and stage of lactation to receive the Ovsynch protocol [OVS; synchronization of ovulation by injecting GnRH 7 d before and 48 h after PGF(2alpha), followed by one fixed-time AI (TAI) 16 to 20 h after the second GnRH injection] or Ovsynch plus a controlled internal drug release (CIDR) P4-releasing insert for 7 d, beginning at the first GnRH injection (OVS + CIDR). Blood was sampled to quantify P4 10 d before the first GnRH injection, immediately before the first GnRH injection, at the time of CIDR removal, before the PGF(2alpha) injection (1 to 2 h after CIDR insert removal), and 48 h after the PGF(2alpha) injection to determine cyclicity status before initiation of treatment, luteal status at the PGF(2alpha) injection, and incidence of luteal regression. Overall, conception rates at 28 (40 vs. 50%) and 56 d (33 vs. 38%) after TAI differed between OVS and OVS + CIDR, respectively; but a treatment x location interaction was detected. Compared with OVS, pregnancy outcomes were more positive for OVS + CIDR cows at 4 of 6 locations 28 d after TAI and at 3 of 6 locations 56 d after TAI. An interaction of luteal status (high vs. low) before CIDR insert removal and PGF(2alpha) injection with pretreatment cycling status indicated that cows having low P4 at PGF(2alpha) injection benefited most from P4 supplementation (OVS + CIDR = 36% vs. OVS = 18%), regardless of pretreatment cycling status. Pregnancy loss between 28 and 56 d after TAI was greater for noncycling cows (31%) compared with cycling cows (16%). Pregnancy loss for cows receiving P4 (21%) did not differ from that for cows not receiving P4 (21%). Supplementation of P4, pretreatment cycling status, and luteal status before PGF(2alpha) injection altered follicular diameters at the time of the second GnRH injection, but were unrelated to pregnancy outcomes. Incidence of multiple ovulation was greater in noncycling than in cycling cows. Further, cows having multiple ovulations had improved pregnancy outcomes at 28 and 56 d after TAI. In summary, a CIDR insert during the Ovsynch protocol increased fertility in lactating cows having low serum P4 before PGF(2alpha) injection. Improved pregnancy outcomes were observed at some, but not all locations.

No abstract

Diabetic heart disease is a distinct clinical entity that can progress to heart failure and sudden death. However, the mechanisms responsible for the alterations in excitation-contraction coupling leading to cardiac dysfunction during diabetes are not well known. Hyperglycemia, the landmark of diabetes, leads to the formation of advanced glycation end products (AGEs) on long-lived proteins, including sarcoplasmic reticulum (SR) Ca2+ regulatory proteins. However, their pathogenic role on SR Ca2+ handling in cardiac myocytes is unknown. Therefore, we investigated whether an AGE cross-link breaker could prevent the alterations in SR Ca2+ cycling that lead to in vivo cardiac dysfunction during diabetes. Streptozotocin-induced diabetic rats were treated with alagebrium chloride (ALT-711) for 8 weeks and compared to age-matched placebo-treated diabetic rats and healthy rats. Cardiac function was assessed by echocardiographic examination. Ventricular myocytes were isolated to assess SR Ca2+ cycling by confocal imaging and quantitative Western blots. Diabetes resulted in in vivo cardiac dysfunction and ALT-711 therapy partially alleviated diastolic dysfunction by decreasing isovolumetric relaxation time and myocardial performance index (MPI) (by 27 and 41% vs. untreated diabetic rats, respectively, P < 0.05). In cardiac myocytes, diabetes-induced prolongation of cytosolic Ca2+ transient clearance by 43% and decreased SR Ca2+ load by 25% (P < 0.05); these parameters were partially improved after ALT-711 therapy. SERCA2a and RyR2 protein expression was significantly decreased in the myocardium of untreated diabetic rats (by 64 and 36% vs. controls, respectively, P < 0.05), but preserved in the treated diabetic group compared to controls. Collectively, our results suggest that, in a model of type 1 diabetes, AGE accumulation primarily impairs SR Ca2+ reuptake in cardiac myocytes and that long-term treatment with an AGE cross-link breaker partially normalized SR Ca2+ handling and improved diabetic cardiomyopathy.

An understanding of the mechanisms involved in the regulation of reproductive processes in yellow perch is fundamental for intensive culture of this commercially important, freshwater, perciform fish. This paper describes the annual reproductive cycle of female and male perch. It presents the current state of knowledge on the regulation of ovarian steroidogenesis, final maturation of oocytes and ovulation in this species. Moreover, data concerning biochemistry of spermatozoa and seminal plasma as well as testicular steroidogenesis are summarized. In addition to endocrinological factors, the involvement of environmental (photoperiod and temperature) cues in the regulation of yellow perch reproduction is reviewed. Finally, practical aspects of controlling perch reproduction are outlined.