Effect of xylazine,isoxsuprine, and lidocaine on Doppler sonographic uterine and umbilical blood flow measurements in cows during the last month of pregnancy

The maternal portion of the bovine placenta receives blood mainly from the uterine arteries (AUT) and the fetal portion from the umbilical arteries (AUM). Placental perfusion is crucial for fetal development and undergoes adaptive changes during pregnancy according to the fetal requirements. One goal of this study was to investigate changes in Doppler sonographic measurements of blood vessels that supply blood to the placenta in cows during the last 4 weeks of pregnancy. Another goal was to examine how these measurements are affected by three drugs commonly used in cows at the time of parturition. Nine cows underwent Doppler sonographic examination of the AUT ipsilateral and contralateral to the pregnant horn and one AUM three times per week during the last 4 weeks of gestation. This was followed by the randomized administration of one of the three following experimental drugs per day: isoxsuprine (200 mg/cow, iv), xylazine (2 mg/100 kg, iv), and lidocaine for epidural anesthesia (100 mg/cow). Doppler sonographic examination was repeated 30 minutes after medication. Maternal pulse rate increased during the study period (P < 0.001), and the diameter of the contralateral AUT was smaller in the last week before birth than in the two preceding weeks. The resistance index (RI) of the ipsilateral AUT was smaller in the last week than in the first 2 weeks of the study period. Uterine blood flow volume increased after isoxsuprine by 5% and after epidural anesthesia by 6% (both P ≤ 0.05) and decreased after xylazine by 10% (P < 0.001). Isoxsuprine was the only drug that elevated the blood flow volume in the AUM (P ≤ 0.05). Xylazine increased the RI of both AUT (both P < 0.001) and significantly reduced maternal and fetal pulse frequencies, whereas isoxsuprine significantly reduced the RI of both AUT and the AUM and increased maternal and fetal pulse frequencies. The results reported that Doppler sonographic measurements of uterine and AUM change little in the last month of pregnancy in the cow. Isoxsuprine and epidural anesthesia with lidocaine have the potential to improve uterine perfusion.     

Effect of intraovarian proximity between dominant follicle and corpus luteum on dimensions and blood flow of each structure in heifers

An intraovarian positive physiologic coupling between the extant CL and the ipsilateral preovulatory follicle (PF) or the future or established postovulatory dominant follicle (DF) was studied in 26 heifers. Ovaries were scanned by ultrasonic imaging from Day 16 (Day 0 = ovulation) of the preovulatory period until Day 6 of the postovulatory period. Hemodynamics of the follicles and CL were assessed by color-Doppler ultrasonography. When the PF and CL were ipsilateral compared with contralateral, blood-flow resistance in wall of the PF was lower (P < 0.04) on Days –2 and –1, and percentage blood-flow signals in the CL approached being greater (P < 0.08) on Days –4 to –1. During the postovulatory period, percentage of DF wall with blood-flow signals (44.1 ± 1.2% vs. 31.4 ± 2.8%) and percentage of CL with blood-flow signals (51.8 ± 1.2% vs. 42.5 ± 3.1%) were each greater (P < 0.05) when the two ipsilateral structures were adjacent (distance between antrum and CL wall, ≤ 3 mm) than when separated. On Day 0, the distance between follicle and ipsilateral CL was less (P < 0.02) for the future DF than for the future largest subordinate. Growth rate between Days 0 and 2 averaged over all growing follicles was greater (P < 0.01) when the follicles were ≤3 mm from the CL (1.1 ± 0.1 mm/day) than when farther from the CL (0.9 ± 0.1 mm/day). Results supported the hypotheses that (1) a positive intraovarian coupling occurs between the PF or postovulatory DF and the extant CL and (2) the coupling is enhanced when the ipsilateral DF and CL are in close proximity.     

The effect of isosorbide dinitrate on uterine and ovarian blood flow in cycling and early pregnant mares: A pilot study

Poor uterine perfusion has been proposed as a cause of infertility in mares. The objective of this study was to investigate the effect of isosorbide dinitrate (ISDN), a nitric oxide donor, on uterine and ovarian blood flow resistance during diestrus and early pregnancy in mares. Six Trotter mares, aged 7 to 14 years, were examined daily during the first 11 days of three diestrous periods, and five of those mares were also examined during the first 11 days of two pregnancies. Six mares randomly received a placebo, a low dose (30 mg, ISDN30), or a high dose of ISDN (60 mg, ISDN60) through three nonconsecutive cycles. The treatments were administered orally, every 12 hours from Day 1 to 11 of the cycle (Day 0 = ovulation). Five of the 6 mares received a placebo or 60 mg of ISDN orally every 12 hours from Day 1 to 11 of pregnancy. The mares were short cycled on Day 12 of each trial. Transrectal color Doppler was used to determine blood flow resistance semiquantitatively and expressed as pulsatility index. Mean pulsatility index of both uterine arteries combined and of the dominant (ipsilateral to the CL) ovarian artery was lower (treatment effects: P ≤ 0.01; time effects: P ≤ 0.002) in mares receiving 30 mg or 60 mg of ISDN compared with placebo-treated mares. Blood flow resistance in the dominant ovarian artery was lower in ISDN-treated pregnant mares than in placebo-treated pregnant and cycling mares (treatment effect: P = 0.04; time effect: P = 0.003). Isosorbide dinitrate increases uterine and ovarian perfusion in cycling mares and ovarian perfusion in early pregnant mares. Further studies are needed to investigate these effects in relation to fertility of the mare.     

Effect of resynchronization with GnRH on day 21 after artificial insemination on pregnancy rate and pregnancy loss in lactating dairy cows

The objectives of the present study were to determine the effects of resynchronization with GnRH on Day 21 after artificial insemination (AI) on pregnancy rate and losses of pregnancy in lactating dairy cows. Holstein cows (n=585) on two dairy farms were assigned to one of two treatments in a randomized complete block design. On Day 21 after a pre-enrollment AI, animals assigned to the resynchronization (RES) group received 100 microg of GnRH i.m., whereas animals in the control (CON) group received no treatment. All animals were examined ultrasonographically on Days 21 and 28 after AI, and blood samples were taken for progesterone measurement on Day 21. Pregnancy was diagnosed on Day 28 and reconfirmed 14 days later. Nonpregnant cows on Day 28 were inseminated using timed AI after the completion of the Ovsynch protocol 10 and 17 days after enrollment in the study for RES and CON groups, respectively. Progesterone concentration > or =2.35 ng/ml was used as an indicator of pregnancy on Day 21. For RES and CON cows, pregnancy rate at Days 21 (70.9% versus 73.0%, P<0.56), 28 (33.1% versus 33.6%; P<0.80) and 42 (27.0% versus 26.8%; P<0.98) after the pre-enrollment AI did not differ. Administration of GnRH on Day 21 after AI had no effect on pregnancy loss in RES and CON groups from days 21 to 28 (53.2% versus 53.5%; P<0.94) and days 28 to 42 (17.9%; P<0.74) after AI. Pregnancy rate after the resynchronization period was similar for both treatment groups. Resynchronization with GnRH given on Day 21 after AI for initiation of a timed AI protocol prior to pregnancy diagnosis does not affect pregnancy rate and pregnancy loss in lactating dairy cows.     

Lack of complete regression of the Day 5 corpus luteum after one or two doses of PGF2α in nonlactating Holstein cows

The early corpus luteum (CL) (before Day 6) does not regress after a single PGF_2α treatment. We hypothesized that increasing PGF_2α dose or number of treatments would allow regression of the early CL (Day 5). Nonlactating Holstein cows (N = 22) were synchronized using the Ovsynch protocol. On Day 5 (Day 0 = second GnRH treatment), cows were assigned to: (1) control (N = 5): no further treatment; (2) 1PGF (N = 6): one dose of 25 mg PGF_2α; (3) 2PGF (N = 5): two doses of 25 mg PGF_2α (50 mg) given 8 hours apart (second PGF_2α on Day 5 at the same time as the other PGF_2α treatments); (4) DPGF (N = 6): double dose of 25 mg PGF_2α (50 mg) given on Day 5. Blood samples were collected to monitor progesterone (P4) profiles in two periods. In the first period (0 to 24 hours), there were effects of treatment (P = 0.01), time (P < 0.01), and an interaction of treatment and time (P = 0.02). Group 1PGF versus control was different only at 12 hours (P = 0.02). Cows treated with DPGF were different than control at 4 hours (P = 0.04), 12 hours (P < 0.01), and 24 hours (P < 0.01). Only cows treated with 2PGF had lower P4 than control during the entire period and low P4 (0.37 ± 0.17 ng/mL) at 24 hours, usually indicative of luteolysis. In the second period (Day 5 to 15 of the cycle), there were effects of treatment (P < 0.01), time (P < 0.01), and interaction of treatment and time (P = 0.002). Group 1PGF was not different than control from Day 5 to 13 and P4 was greater than control on Day 14 (P = 0.01) and 15 (P < 0.01). Circulating P4 in DPGF cows was lower than control from Day 7 (P = 0.05) through 12 (P < 0.01). Likewise, there were differences between control and 2PGF from Day 7 to 13, but not on Day 14 and 15. On Day 15, all PGF_2α-treated groups had circulating P4 consistent with an active CL. Ultrasound evaluation confirmed that no CL from any group completely regressed during the experiment and no new ovulations occurred to account for functional CL later in cycle. In summary, a double dose of PGF_2α (twice on Day 5 or 8 hours apart) can dramatically decrease P4, consistent with classical definitions of luteolysis; however, these CL recover and become fully functional. Thus, the Day 5 CL of mature Holstein cows do not regress even to two doses of PGF_2α.     

Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply.

Blood flow to each uterine horn of cows during the oestrous cycle and early pregnancy was determined daily by use of electromagnetic blood flow probes placed around both middle uterine arteries. The pattern of blood flow to uteri of pregnant and non-pregnant cows was similar until Day 14 after mating or oestrus. Between Days 14 and 18 of pregnancy blood flow to the uterine horn containing the conceptus increased (P less than 0.01) 2- to 3-fold, whereas blood flow to the non-gravid uterine horn in these cows remained constant. No corresponding increase in blood flow to the uterine horn ipsilateral to the ovary bearing the CL was observed in non-pregnant cows during this 4-day period. By Day 19 of pregnancy, blood flow to the gravid uterine horn had returned to a level similar to that observed on Day 13. Blood flow to both uterine horns of pregnant cows remained constant from Days 19 to 25 and then increased to the gravid horn (P less than 0.01) markedly until Day 30 whereas blood flow to the non-gravid horn remained low. Uterine blood flow during the oestrous cycle of non-pregnant cows was positively correlated (P less than 0.01) with systemic concentrations of oestradiol and the ratio of oestradiol (pg/ml) to progesterone (ng/ml). There was no association between oestradiol concentrations and blood flow to the gravid uterine horn. These data indicate local control of uterine blood flow by the bovine conceptus which may function to create optimal conditions for the continuation of pregnancy.     

Prostaglandin E1 or E2 inhibits an oxytocin-induced premature luteolysis in ewes when oxytocin is given early in the estrous cycle

The objective of this study was to determine whether PGE₁ or PGE₂ prevents a premature luteolysis when oxytocin is given on Days 1 to 6 of the ovine estrous cycle. Oxytocin given into the jugular vein every 8 hours on Days 1 to 6 postestrus in ewes decreased (P ≤ 0.05) luteal weights on Day 8 postestrus. Plasma progesterone differed (P ≤ 0.05) among the treatment groups; toward the end of the experimental period, concentrations of circulating progesterone in the oxytocin-only treatment group decreased (P ≤ 0.05) when compared with the other treatment groups. Plasma progesterone concentrations in ewes receiving PGE₁ or PGE₁ + oxytocin were greater (P ≤ 0.05) than in vehicle controls or in ewes receiving PGE₂ or PGE₂ + oxytocin and was greater (P ≤ 0.05) in all treatment groups receiving PGE₁ or PGE₂ than in ewes treated only with oxytocin. Chronic intrauterine treatment with PGE₁ or PGE₂ also prevented (P ≤ 0.05) oxytocin decreases in luteal unoccupied and occupied LH receptors on Day 8 postestrus. Oxytocin given alone on Days 1 to 6 postestrus in ewes advanced (P ≤ 0.05) increases in PGF_2α in inferior vena cava or uterine venous blood. PGE₁ or PGE₂ given alone did not affect (P ≥ 0.05) concentrations of PGF_2α in inferior vena cava and uterine venous blood when compared with vehicle controls or oxytocin-induced PGF_2α increases (P ≤ 0.05) in inferior vena cava or uterine venous blood. We concluded that PGE₁ or PGE₂ prevented oxytocin-induced premature luteolysis by preventing a loss of luteal unoccupied and occupied LH receptors.     

Phenotyping of leukocytes and granulocyte and monocyte phagocytic activity in the peripheral blood and uterus of cows with endometritis

This study was a comparative evaluation of selected immunological parameters in peripheral blood and uterine wash samples from cows with a normal postpartum period compared with cows with endometritis. We aimed to determine the usefulness of these parameters in monitoring the puerperium. In total, 40 cows were included in the study: 20 had endometritis (experimental group), and 20 did not have uterine inflammation (control group). Animals were chosen on the basis of cytological and bacteriological test results. The tests were conducted 5, 22, and 40 days postpartum. In both groups, flow cytometric analysis of the surface molecules CD4, CD8, CD21, CD25, and CD14 in the peripheral blood and uterine washings was performed. Granulocyte and monocyte phagocytic activity was determined using a commercial Phagotest kit that was adapted for flow cytometry. The percentage of phagocytic granulocytes and monocytes in both the peripheral blood and the uterine washings was significantly lower for cows in the experimental group compared with the control group (P < 0.01). A significant decrease (P < 0.01) in the percentage of CD4+, CD25+, CD14+, and CD4 + CD25^high leukocyte subpopulations was also observed in the peripheral blood of cows with endometritis. A significant decrease (P < 0.01) in CD21+ lymphocytes and an increase in CD8+ lymphocytes was detected in uterine washings. The results of this work indicate that cell immunity dysfunction may be the main factor causing advanced inflammation of the uterus in endometritis. Knowledge of the immunological mechanisms observed in cows with endometritis might aid in choosing the correct immunomodulating agent–based adjuvant therapy.     

Uterine artery flow velocity waveform,arterial flow indices,follicular dynamics,and sex hormones during preovulatory period in synchronized ovulatory cycle of Bos indicus beef cows

A greater understanding of the uterine artery’s (UtA) biology is essential to the increase in female reproductive abilities. The UtA flow velocity waveform, blood flow volume (BFV), pulsatility and resistance indices (PI and RI), blood flow velocities, dynamics of the dominant follicle (DF), and estradiol (E2) and progesterone (P4) levels in an induced ovulatory cycle were evaluated in Thai native cattle. Twenty cows were induced with synchronized ovulation through a P4-releasing device, from Day ?9 to Day ?4, concurrent with the administration of two doses of a gonadotropin-releasing hormone on Day ?9 and Day ?1, and two doses of prostaglandin F_2α on Day ?4 and 8?h later. Day 0 was designated as the day of ovulation. The cows underwent Doppler sonographic determination and blood collection from Day ?4 to Day 0. The cows were classified in the non-ovulating (n?=?5) and ovulating groups (n?=?15). The ovulating cows presented higher BFV values, blood flow velocities, DF growth rates, and E2 levels; yet lower PI values and P4 concentrations, than those of the non-ovulating cows. The BFV values and the blood flow velocities were greater, but the RI and PI values were lower in the ovulatory side UtA than in the contraovulatory side UtA. The BFV values were positively correlated with blood flow velocities, DF growth rates and E2 concentrations in the ovulating cows; confirming the importance of UtA blood flow, follicular growth, and E2-vasodilation during preovulatory phase in the induced ovulatory cycle of Bos indicus beef cows.     

Effect of PGF2α and GnRH on the reproductive performance of postpartum dairy cows subjected to synchronization of ovulation and timed artificial insemination during the warm or cold periods of the year

This study was designed to evaluate the reproductive performance of lactating dairy cows (Holstein Friesian) after the injection of PGF_2α analogue on Day 15 postpartum, and GnRH analogue on Day 23 after artificial insemination (AI) with Presynch (two injections of PGF_2α, administered 14 days apart starting at 30–35 days postpartum) + Ovsynch-based (GnRH–7 days–PGF_2α–2 days–GnRH–16–20 hours–timed artificial insemination) treatments, during the warm and cold periods of the year. All the cows (n = 313) were assigned to one of the four groups including: M₁ (n = 72) in which the cows were treated with PGF_2α on Day 15 postpartum + Presynch-Ovsynch + GnRH on Day 23 post-AI; M₂ (n = 41) in which the cows received PGF_2α on Day 15 postpartum + Presynch-Ovsynch; M₃ (n = 100) including the cows that got Presynch-Ovsynch; and control group (n = 100) including the cows that were not treated and were inseminated at natural estrus. Pregnancy diagnosis was performed 28 to 35 days post-insemination by means of ultrasound. The results showed that treatment with PGF_2α on Day 15 postpartum significantly decreased the days to conception and the number of services per conception (P < 0.01) and it also improved the first service conception rate (P < 0.1) only in cows that were treated with M₂ protocol. Whereas, the days to first service was not influenced by the treatment of PGF_2α on Day 15 postpartum (P > 0.05). In contrast, administration of GnRH on Day 23 post-AI increased the days to conception and the number of service per conception (P < 0.01) and tended to decrease the first service conception rate (P < 0.1) in cows that were treated with M₁ compared with M₂ protocol. Therefore, it was concluded that Presynch-Ovsynch protocol could be more reproductive and beneficial when a single treatment with PGF_2α was administered at 15 days postpartum (15 days after the PGF_2α, Presynch-Ovsynch protocol was initiated). Interestingly, the administration of a GnRH agonist on Day 23 post-AI not only did not improve the reproductive performance of the cows receiving first postpartum timed artificial insemination after Presynch-Ovsynch protocol but also reduced that.     

Inflammatory cytokine concentrations in uterine flush and serum samples from dairy cows with clinical or subclinical endometritis

The objective of this study was to compare the concentrations of inflammatory cytokines in uterine flush and serum from healthy postpartum dairy cows and cows with clinical or subclinical endometritis. Clinical endometritis was diagnosed by observation of vaginal discharges (>50% pus) and subclinical endometritis was diagnosed by evaluation of uterine cytology (neutrophils >18%) at 4 weeks postpartum. Uterine flush was obtained from 48 cows at 4, 6, and 8 weeks postpartum for evaluation of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10 concentrations. Serum samples were obtained from 34 cows just after calving and at 1, 2, 4, 6, and 8 weeks postpartum for evaluation of TNF-α, IL-1β, and IL-6 concentrations. Concentrations of TNF-α, IL-6, and IL-10 were greater (P < 0.05) in cows with clinical endometritis than in cows with subclinical endometritis and healthy controls, whereas concentrations of IL-8 in both cows with clinical and subclinical endometritis were greater (P < 0.005) than in controls. Overall, IL-6 and IL-10 concentrations decreased during the postpartum period. IL-1β concentrations in cows with clinical endometritis decreased (P < 0.0005) during the postpartum, whereas concentrations in cows with subclinical endometritis and controls did not change significantly with time; at 4 weeks postpartum, concentrations were greater (P < 0.0001) in cows with clinical endometritis. There were no significant effects of group, sampling time, or interaction on serum cytokine concentrations. In conclusion, cows with endometritis have greater inflammatory cytokine concentrations in uterine flush than healthy cows, but no differences were observed in serum.     

Conceptus ecobiometry and triplex Doppler ultrasonography of uterine and umbilical arteries for assessment of fetal viability in dogs

The objectives were to: 1) evaluate blood flow in the uterine (UA) and umbilical (Uma) arteries in the pregnant bitch, by measuring the resistive index (RI) and pulsatility index (PI); 2) to note the presence or absence of the early diastolic notch and diastolic flow in the UA and Uma flow waveforms, respectively; and 3) perform conceptus ecobiometry for fetal growth assessment during pregnancy. Six healthy bitches were examined on approximately Days -44, -42, -36, -31, -28, -25, -21, -18, -14, -8, -4, and -2 of pregnancy (whelping = Day 0). Triplex Doppler and B-mode ultrasonography were used to assess blood flow and conceptus ecobiometry. All pregnancies ended with a normal whelping and birth of live puppies. Prior to whelping, all conceptus dimensions increased significantly, whereas RI and PI of both the Uma and UA decreased significantly. For the UA, RI and PI were (mean ± SEM) 0.95 ± 0.02 and 2.75 ± 0.41, respectively, on Day -44, and were 0.60 ± 0.01 and 0.99 ± 0.03 on Day -4. For the Uma, RI and PI were 0.99 ± 0.01 and 2.42 ± 0.03 on Day -31, and were 0.62 ± 0.01 and 1.15 ± 0.02 on Day -4. The complete disappearance of the early diastolic notch in the UA, and the appearance of diastolic flow in the Uma occurred on Days -16 ± 5 and -21 ± 1. The authors concluded that UA and Uma perfusion were important end points to assess fetal vitality in bitches. Furthermore, the current reference values provided a baseline for monitoring normal and abnormal pregnancies in bitches.     

Effects of rumen-protected methionine and choline supplementation on the preimplantation embryo in Holstein cows

Our objective was to determine the effects of supplementing methionine and choline during the prepartum and postpartum periods on preimplantation embryos of Holstein cows. Multiparous cows were assigned in a randomized complete-block design into four treatments from 21 days before calving to 30 days in milk (DIM). Treatments (TRT) were MET (n = 9, fed the basal diet + rumen-protected methionine at a rate of 0.08% [w:w] of the dry matter [DM], Smartamine M), CHO (n = 8, fed the basal diet + choline 60 g/d, Reashure), MIX (n = 11, fed the basal diet + Smartamine M and 60 g/d Reashure), and CON (n = 8, no supplementation, fed the close-up and fresh cow diets). Cows were randomly reassigned to two new groups (GRP) to receive the following diets from 31 to 72 DIM; control (CNT, n = 16, fed a basal diet) and SMT (n = 20, fed the basal diet + 0.08% [w:w] of the dry matter intake as methionine). An progesterone intravaginal insert (CIDR) device was inserted in all cows after follicular aspiration (60 DIM) and superovulation began at Day 61.5 using FSH in eight decreasing doses at 12-hour intervals over a 4-day period. On Days 63 and 64, all cows received two injections of PGF2α, and CIDR was removed on Day 65. Twenty-four hours after CIDR removal, ovulation was induced with GnRH. Cows received artificial insemination at 12 hours and 24 hours after GnRH. Embryos were flushed 6.5 days after artificial insemination. Global methylation of the embryos was assessed by immunofluorescent labeling of 5-methylcytosine, whereas lipid content was assessed by staining with Nile red. Nuclear staining was used to count the total number of cells per embryo. There was no difference between TRT, GRP, or their interaction (P > 0.05) for embryo recovery, embryos recovered, embryo quality, embryo stage, or cells per embryo. Methylation of the DNA had a TRT by GRP interaction (P = 0.01). Embryos from cows in CON-CNT had greater (P = 0.04) methylation (0.87 ± 0.09 arbitrary units [AU]) than embryos from cows in MET-CNT (0.44 ± 0.07 AU). The cytoplasmic lipid content was not affected (P > 0.05) by TRT or their interaction, but lipid content was greater (P = 0.04) for SMT (7.02 ± 1.03 AU) than that in CNT (3.61 ± 1.20 AU). In conclusion, cows in MET-CNT had embryos with lower methylation, and SMT cows had a higher lipid content than CNT. Methionine supplementation seems to impact the preimplantation embryo in a way that enhances its capacity for survival because there is strong evidence that endogenous lipid reserves serve as an energy substrate.     

Corpus luteum development and function and relationship to pregnancy during the breeding season in the Mediterranean buffalo

The aim of this study was to ascertain corpus luteum (CL) development and function in buffaloes synchronized and mated by artificial insemination (AI) during the breeding season. Italian Mediterranean buffalo cows (n = 43) at 86.5 ± 2.7 days postpartum were synchronized by the Ovsynch-TAI Program and inseminated using frozen thawed semen at 20 and 44 h after the second injection of GnRH. The CL dimensions (diameter and area) and blood flow were examined on Days 5, 10, 15, 20, and 25 after AI by realtime B-mode/colour-Doppler ultrasonography. The resistive index (RI), pulsatility index (PI) and time average medium velocity (TAMV) were recorded at each time, together with CL dimensions. Blood samples were taken on the days of ultrasonography for progesterone (P4) assay by RIA. Data were grouped into pregnant or non-pregnant and retrospectively analyzed by repeated measure ANOVA and correlation analyses. Dimensions of the CL on Days 10, 20, and 25 after AI were greater (P < 0.01) in buffaloes pregnant on Day 45 (n = 18) compared with non-pregnant buffaloes (n = 25). The former buffaloes also showed a greater (P < 0.01) rate of CL growth between Days 5 and 10 after AI. Blood flow to the CL on Day 10 after AI showed a higher TAMV (P < 0.01) and lower RI (P < 0.05) in pregnant buffaloes compared with non-pregnant buffaloes. Negative correlations were observed on Day 10 after AI between CL diameter and RI (r = −0.61; P < 0.01) and PI (r = −0.60; P < 0.01); P4 concentrations and RI (r = −0.46; P < 0.02); and RI and pregnancy (r = 0.45; P < 0.02). Positive correlations were observed between pregnancy and CL size (r = 0.54; P < 0.01), ΔCL diameter between Days 5 and 10 (r = 0.52; P < 0.01), ΔCL area between Days 5 and 10 (r = 0.48; P < 0.015), and ΔP4 between Days 5 and 10 (r = 0.50; P < 0.01). Based on these findings it is concluded that the period between Day 5 and 10 is very important for CL growth and crucial in evaluating pregnancy. Accordingly, the assessment of CL parameters during the period from Day 5 to Day 10 after AI might be used to predict the likelihood of an ongoing pregnancy.     

Response of the Cholesterol Metabolism to a Negative Energy Balance in Dairy Cows Depends on the Lactational Stage

The response of cholesterol metabolism to a negative energy balance (NEB) induced by feed restriction for 3 weeks starting at 100 days in milk (DIM) compared to the physiologically occurring NEB in week 1 postpartum (p.p.) was investigated in 50 dairy cows (25 control (CON) and 25 feed-restricted (RES)). Blood samples, liver biopsies and milk samples were taken in week 1 p.p., and in weeks 0 and 3 of feed restriction. Plasma concentrations of total cholesterol (C), phospholipids (PL), triglycerides (TAG), very low density lipoprotein-cholesterol (VLDL-C) and low density lipoprotein-cholesterol (LDL-C) increased in RES cows from week 0 to 3 during feed restriction and were higher in week 3 compared to CON cows. In contrast, during the physiologically occurring NEB in week 1 p.p., C, PL, TAG and lipoprotein concentrations were at a minimum. Plasma phospholipid transfer protein (PLTP) and lecithin:cholesterol acyltransferase (LCAT) activities did not differ between week 0 and 3 for both groups, whereas during NEB in week 1 p.p. PLTP activity was increased and LCAT activity was decreased. Milk C concentration was not affected by feed restriction in both groups, whereas milk C mass was decreased in week 3 for RES cows. In comparison, C concentration and mass in milk were elevated in week 1 p.p. Hepatic mRNA abundance of sterol regulatory element-binding factor-2 (SREBF-2), 3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1), 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), and ATP-binding cassette transporter (ABCA1) were similar in CON and RES cows during feed restriction, but were upregulated during NEB in week 1 p.p. compared to the non-lactating stage without a NEB. In conclusion, cholesterol metabolism in dairy cows is affected by nutrient and energy deficiency depending on the stage of lactation.     

Donor category and seasonal climate associated with embryo production and survival in multiple ovulation and embryo transfer programs in Holstein cattle

The present study investigated the effect of Holstein donor category (cows vs. heifers) and climate variation (hot vs. cooler season) on the efficiency of in vivo embryo production programs as well as embryo survival after transferred to Holstein recipient cows. A total of 1562 multiple ovulation (MO) procedures (cows: n = 609, and heifers: n = 953) and 4076 embryo transfers (ETs) performed in two dairy herds were evaluated. Donor cows had greater number of CLs (10.6 ± 0.6 vs. 7.5 ± 0.4; P < 0.0001) and ova/embryos recovered (7.6 ± 0.6 vs. 4.6 ± 0.4; P < 0.0001) compared with donor heifers. However, fertilization rate (47.9 vs. 82.4%; P < 0.0001) and proportion of transferable embryos (31.5 vs. 67.4%; P < 0.0001) were lower in donor cows than heifers, respectively. Regardless of donor category, the proportion of freezable embryos was less (P < 0.001) during hot season than in cooler season (21.4 vs. 32.8%). However, greater decline in the proportion of freezable embryos during the hot season was observed in cows (21.7 vs. 10.7%) compared with heifers (46.2 vs. 38.1%; P = 0.01). In contrast, the season on which the embryo was produced (hot or cool) did not affect pregnancy rate on Day 31 (30.5 vs. 31.7%; P = 0.45) and 45 (25.3 vs. 25.1%; P = 0.64) of pregnancy. Regardless of the season in which the embryos were produced, embryonic survival after transferring embryos retrieved from donor cows was greater on Days 31 (36.0 vs. 30.7%; P = 0.001) and 45 (28.3 vs. 23.1%; P = 0.001) of pregnancy when compared with embryos from donor heifers. In conclusion, MO embryo production efficiency decreased during the hot seasons both in cows and heifers; however, the decline was more pronounced in donor cows. Regardless of the embryo source, similar pregnancy rate was observed in the recipient that received embryos produced during the hot and cooler seasons. Curiously, embryos originating from donor cows had higher embryonic survival when transferred to recipient cows than embryos originating from heifers.     

Effects of increasing crude protein concentrations on performance and carcass characteristics of growing and finishing steers and heifers

A 2 × 3 factorial design was utilized to ascertain the effects of three dietary crude protein (CP) concentrations on performance, carcass characteristics, and serum urea nitrogen (SUN) concentration in steers and heifers. Animals were blocked by gender (n = 9) and body weight (BW; n = 3/gender), randomly assigned to a diet containing 110, 125 or 140 g/kg dietary CP (n = 6), subjected to a growing period of 56, 84 or 112 d, depending on start BW, and a finishing period of 84 d. Animals were weighed and bled at 28 d intervals and daily dry matter intake (DMI), average daily gain (ADG), and gain to feed (G:F) were calculated and SUN was analyzed as a repeated measure throughout the study. Following slaughter, carcass data was collected for hot carcass weight (HCW), dressing percent (DP), kidney, pelvic and heart fat (KPH), 12th rib backfat (BF), loin muscle (LM) area, marbling score (MS), and yield grade (YG). Growing steers and heifers were programmed to gain 1.02 and 0.91 kg/d, respectively. Therefore, heifers consumed less than steers and steers gained more than heifers (P<0.01) with no differences in feed efficiency. Dietary CP treatment did not effect DMI, but did result in a quadratic (P=0.04) increase in ADG; thereby quadratically (P=0.06) and linearly (P=0.08) increasing final BW, and G:F, respectively. Finishing heifers consumed and gained less than steers (P<0.01), had lighter HCW (P<0.01) and greater DP (P=0.01) and LM area (P=0.01) than steers. DMI (P=0.02), ADG (P=0.05), HCW (P=0.08), and DP (P=0.06) reacted quadratically with increasing dietary CP. HCW (P=0.02) increased linearly with increasing dietary CP. G:F, KPH, BF, LM area, MS and YG was not affected by dietary CP concentration and G:F, KPH, BF, MS, and YG did not differ between genders. However, there was a gender × dietary CP interaction (P=0.01) for G:F. Steers were the most efficient at 125 g/kg dietary CP, while heifers were most efficient at 140 g/kg dietary CP. Gender had no effect on SUN concentrations, but SUN increased linearly (P<0.01) with increasing dietary CP concentrations. In conclusion, quadratic responses in DMI and ADG indicate that a 125 g/kg dietary CP concentration is optimal for either steers or heifers during the finishing period.     

Effects of dietary supplementation of pioglitazone on metabolism,milk yield,and reproductive performance in transition dairy cows

The objective of this study was to investigate the effect of dietary supplementation of pioglitazone (PGT), a specific ligand for PPARγ, on metabolic dynamics, milk production, and reproductive performance of transition dairy cows. Eighty multiparous Holstein cows in their second or more lactations were blocked by the calving date and parity and assigned randomly to four dietary groups (n = 20 cow/treatment) including control (no PGT−/−), supplemented with PGT (6-mg PGT/kg body weight) from Day −14 to +21 relative to parturition (PGT+/+) or only during prepartum (PGT+/−) or postpartum periods (PGT−/+). Postpartum body condition score and body weight loss decreased (P < 0.05) in all PGT-supplemented groups. Milk yield was not affected by PGT supplementation (P > 0.05). Percentage of milk fat decreased (P < 0.05) in all PGT-treated groups; however, milk fat yield was lower (P < 0.05) in PGT (+/+) and PGT (+/−) groups compared with PGT (−/−). Peripartum (Day −7 to +7) concentrations of plasma nonesterified fatty acids and β-Hydroxybutyrate decreased in PGT (+/+) but not in the PGT (−/−) group (P < 0.05). During the postpartum period, PGT reduced (P > 0.05) plasma concentrations of nonesterified fatty acids in all PGT-treated groups but did not affect β-Hydroxybutyrate level. Plasma concentrations of triglycerides decreased in all PGT-supplemented groups. Supplementation of PGT increased the peripartum concentrations of plasma glucose in PGT (+/+) and PGT (+/−) groups compared with control. Plasma concentrations of insulin-like growth factor 1 were higher in PGT (+/+) compared with the control group during both the peripartum and postpartum periods. Plasma concentrations of growth hormone and insulin were not affected by PGT treatment (P > 0.05). Mean days to ovulation were lower in PGT (+/+) and PGT (-/+), and the proportion of cows ovulating by Day 14 postpartum was higher in PGT (+/+) compared with control. Days open were shorter in PGT (+/+), PGT (+/−), and PGT (−/+) groups compared with control. However, the proportion of pregnant cows at 120 days in milk were higher in all PGT-supplemented groups. The results showed positive effects of dietary supplementation of PGT, especially supplementation during both the prepartum and postpartum periods, on metabolic dynamics, ovarian function, and reproductive performance in transition dairy cows.     

Altered progesterone concentrations by hormonal manipulations before a fixed-time artificial insemination CO-Synch + CIDR program in suckled beef cows

We hypothesized that pregnancy outcomes may be improved by inducing luteal regression, ovulation, or both (i.e., altering progesterone status) before initiating a timed–artificial insemination (TAI) program in suckled beef cows. This hypothesis was tested in two experiments in which cows were treated with either PGF_2α (PG) or PG + GnRH before initiating a TAI program to increase the proportion of cows starting the program in a theoretical marginal (<1 ng/mL; experiment 1) or elevated (≥1 ng/mL; experiment 2) progesterone environment, respectively. The control was a standard CO-Synch + controlled internal drug release (CIDR) program employed in suckled beef cows (100 μg GnRH intramuscularly [IM] [GnRH-1] and insertion of a progesterone-impregnated intravaginal CIDR insert on study Day −10, 25 mg PG and CIDR insert removal on study Day −3, and 100 μg GnRH IM [GnRH-2] and TAI on study Day 0). In both experiments, blood was collected before each injection for later progesterone analyses. In experiment 1, cows at nine locations (n = 1537) were assigned to either: (1) control or (2) PrePG (same as control with a PG injection on study Day −13). The PrePG cows had larger (P < 0.05) follicles on study Day −10 and more (P < 0.05) ovulated after GnRH-1 compared with control cows (60.6% vs. 36.5%), but pregnancy per TAI was not altered (55.5% vs. 52.2%, respectively). In experiment 2, cows (n = 803) at four locations were assigned to: (1) control or (2) PrePGG (same as control with PG injection on study Day −20 and GnRH injection on study Day −17). Although pregnancy per TAI did not differ between control and PrePGG cows (44.0% vs. 44.4%, respectively), cows with body condition score greater than 5.0 or 77 or more days postpartum at TAI were more (P < 0.05) likely to become pregnant than thinner cows or those with fewer days postpartum. Presynchronized cows in both experiments were more (P < 0.05) likely than controls to have luteolysis after initial PG injections and reduced (P < 0.05) serum progesterone; moreover, treatments altered the proportion of cows and pregnancy per TAI of cows in various progesterone categories before the onset of the TAI protocol. In combined data from both experiments, cows classified as anestrous before the study but with elevated progesterone on Day −10 had increased (P < 0.05) pregnancy outcomes compared with anestrous cows with low progesterone concentrations. Progesterone concentration had no effect on pregnancy outcome of cycling cows. In summary, luteal regression and ovulation were enhanced and progesterone concentrations were altered by presynchronization treatments before the 7-day CO-Synch + CIDR program, but pregnancy per TAI was not improved.