Southern ocean carbon and heat impact on climate

The Southern Ocean greatly contributes to the regulation of the global climate by controlling important heat and carbon exchanges between the atmosphere and the ocean. Rates of climate change on decadal timescales are therefore impacted by oceanic processes taking place in the Southern Ocean, yet too little is known about these processes. Limitations come both from the lack of observations in this extreme environment and its inherent sensitivity to intermittent processes at scales that are not well captured in current Earth system models. The Southern Ocean Carbon and Heat Impact on Climate programme was launched to address this knowledge gap, with the overall objective to understand and quantify variability of heat and carbon budgets in the Southern Ocean through an investigation of the key physical processes controlling exchanges between the atmosphere, ocean and sea ice using a combination of observational and modelling approaches. Here, we provide a brief overview of the programme, as well as a summary of some of the scientific progress achieved during its first half. Advances range from new evidence of the importance of specific processes in Southern Ocean ventilation rate (e.g. storm-induced turbulence, sea-ice meltwater fronts, wind-induced gyre circulation, dense shelf water formation and abyssal mixing) to refined descriptions of the physical changes currently ongoing in the Southern Ocean and of their link with global climate. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.

Robust but weak winter atmospheric circulation response to future Arctic sea ice loss

The possibility that Arctic sea ice loss weakens mid-latitude westerlies, promoting more severe cold winters, has sparked more than a decade of scientific debate, with apparent support from observations but inconclusive modelling evidence. Here we show that sixteen models contributing to the Polar Amplification Model Intercomparison Project simulate a weakening of mid-latitude westerlies in response to projected Arctic sea ice loss. We develop an emergent constraint based on eddy feedback, which is 1.2 to 3 times too weak in the models, suggesting that the real-world weakening lies towards the higher end of the model simulations. Still, the modelled response to Arctic sea ice loss is weak: the North Atlantic Oscillation response is similar in magnitude and offsets the projected response to increased greenhouse gases, but would only account for around 10% of variations in individual years. We further find that relationships between Arctic sea ice and atmospheric circulation have weakened recently in observations and are no longer inconsistent with those in models.

Effects of progesterone concentrations and follicular wave during growth of the ovulatory follicle on conceptus and endometrial transcriptome in dairy cows

Objectives were to evaluate the effects of follicular wave and progesterone concentration on growth of the ovulatory follicle, conceptus elongation, uterine IFN-τ concentration, and transcriptome of conceptus and endometrium of pregnant cows on d 17 of gestation. Nonlactating nonpregnant Holstein cows were assigned randomly to one of 3 treatments: ovulation of a first-wave follicle (FW, n = 15); ovulation of a first-wave follicle and progesterone supplementation (FWP4, n = 12); and ovulation of a second-wave follicle (SW, n = 19). Ovulation of a first- or second-wave follicle was achieved by initiating the Ovsynch protocol (d -9 GnRH, d -2 and -1 PGF_2α, d 0 GnRH and artificial insemination, d 0.7 artificial insemination) on d 0 or 6 of a presynchronized estrous cycle, respectively. Cows in FWP4 received 3 intravaginal inserts containing progesterone at 12, 24, and 48 h after the first GnRH injection that were removed on d -2. Cows were killed on d 17 for collection of the reproductive tract. Transcriptome was evaluated by microarray using the Affymetrix Bovine Array. Orthogonal contrasts were built to assess the effects of progesterone concentration during follicle growth (FW vs. FWP4 + SW) and follicular wave (FWP4 vs. SW). Progesterone concentrations (LSM ± SEM) from d -9 to -2 were greater for SW, followed by FWP4 and FW (5.38 ± 0.24, 4.26 ± 0.28, and 1.17 ± 0.27 ng/mL). Diameter of the ovulatory follicle (FW = 19.6 ± 0.6; FWP4 = 15.6 ± 0.6; SW = 15.2 ± 0.5 mm) and concentrations of estradiol from d -2 to 1 (FW = 4.05 ± 0.33; FWP4 = 2.73 ± 0.35; SW = 2.48 ± 0.30 pg/mL) were greater for FW compared with FWP4 and SW. Progesterone concentrations from d 3 to 16 were greater for FW compared with FWP4 and SW. A total of 28 singleton conceptuses were collected (FW, n = 8; FWP4, n = 8; SW, n = 12) and only intact conceptuses were included in the analyses of length (FW, n = 8; FWP4, n = 6; SW, n = 12). Although conceptuses were longer for FW compared with FWP4 and SW (FW = 16.6 ± 2.3; FWP4 = 9.8 ± 2.2; SW = 9.6 ± 2.0 cm), treatment did not affect the amount of IFN-τ in uterine flushing. Transcriptome of conceptuses and endometrium of pregnant cows was not extensively affected by follicular wave (8 and 1 differentially expressed transcripts) or concentration of progesterone during follicle growth (0 and 3 differentially expressed transcripts), showing that these factors did not affect conceptuses and endometrium transcriptome in pregnancies that are maintained to d 17.

Inducing ovulation with oestradiol cypionate allows flexibility in the timing of insemination and removes the need for gonadotrophin-releasing hormone in timed AI protocols for dairy cows

The effects of addition of gonadotrophin-releasing hormone (GnRH) to a progesterone plus oestradiol-based protocol and timing of insemination in Holstein cows treated for timed AI (TAI) were evaluated. Cows (n = 481) received a progesterone device and 2 mg oestradiol benzoate. After 8 days, the device was removed and 25 mg dinoprost was administered. Cows were allocated to one of three (Study 1; n = 57) or four (Study 2; n = 424) groups, accordingly to ovulation inducer alone (Study 1; oestradiol cypionate (EC), GnRH or both) or ovulation inducer (EC alone or combined with GnRH) and timing of insemination (48 or 54 h after device removal; Study 2). In Study 1, the diameter of the ovulatory follicle was greater for GnRH than EC. Oestrus and ovulation rates were similar regardless of ovulatory stimuli. However, time to ovulation was delayed when GnRH only was used. In Study 2, cows treated with GnRH or not had similar pregnancy per AI (P/AI) 30 days (41.5% vs 37.3%; P = 0.28) and 60 days (35.9% vs 33.0%; P = 0.61) after TAI. TAI 48 and 54 h after device removal resulted similar P/AI at 30 days (40.3% vs 38.5%; P = 0.63) and 60 days (33.8% vs 35.1%; P = 0.72). Thus, adding GnRH at TAI does not improve pregnancy rates in dairy cows receiving EC. The flexibility of time to insemination enables TAI of a large number of cows using the same protocol and splitting the time of AI.

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 1 or 2 treatments with prostaglandin F₂α on subclinical endometritis and fertility in lactating dairy cows inseminated by timed artificial insemination

The objectives of the current study were to investigate the efficacy of PGF₂α as a therapy to reduce the prevalence of subclinical endometritis and improve pregnancy per artificial insemination (P/AI) in cows subjected to a timed artificial insemination (AI) program. A total of 1,342 lactating Holstein dairy cows were allocated randomly at 25 ± 3 d in milk (DIM) to remain as untreated controls (control, n=454) or to receive a single PGF₂α treatment at 39 ± 3 DIM (1PGF, n=474) or 2 treatments with PGF(α at 25 ± 3 and 39 ± 3 DIM (2PGF, n=414). All cows were enrolled in the double Ovsynch program at 48 ± 3 DIM and were inseminated at 75 ± 3 DIM. A subset of 357 cows had uterine samples collected for cytological examination at 25 ± 3, 32 ± 3, and 46 ± 3 DIM to determine the percentage of polymorphonuclear leukocytes (PMNL). Subclinical endometritis was defined by the presence of ≥ 5% PMNL. Vaginal discharge score was evaluated at 25 ± 3 DIM and used to define the prevalence of purulent vaginal discharge. Body condition score was assessed at 25 ± 3 DIM. Pregnancy was diagnosed 32 d after AI and reconfirmed 28 d later. At 32 ± 3 DIM, the prevalence of subclinical endometritis was reduced by treatment with PGF₂α at 25 ± 3 DIM in 2PGF (control=23.5% vs. 1PGF=28.3% vs. 2PGF=16.7%); however, this benefit disappeared at 46 ± 3 DIM, and 14% of the cows remained with subclinical endometritis. One or 2 treatments with PGF₂α did not influence P/AI on d 32 or 60 after timed AI, which averaged 39.9 and 35.2%. Similarly, treatment with PGF₂α had no effect on pregnancy loss between 32 and 60 d of gestation (11.9%). Cows diagnosed with both purulent vaginal discharge and subclinical endometritis had the lowest P/AI and the highest pregnancy loss compared with those diagnosed with only 1 of the 2 diseases or compared with cows having no diagnosis of uterine diseases. Interestingly, subclinical endometritis depressed P/AI and increased pregnancy loss only when it persisted until 46 DIM. On d 32 after AI, cows not diagnosed with subclinical endometritis and those that resolved subclinical endometritis by 46 DIM had greater P/AI than those that remained with subclinical endometritis at 46 DIM (45.4 and 40.0 vs. 25.0%, respectively). Similar to P/AI, cows not diagnosed with subclinical endometritis and those that resolved subclinical endometritis by 46 DIM had less pregnancy loss than those with subclinical endometritis at 46 DIM (9.6 and 13.5 vs. 43.9%, respectively). One or 2 treatments with PGF₂α before initiation of the timed AI program were unable to improve uterine health, P/AI, and maintenance of pregnancy in lactating dairy cows. Cows diagnosed with both purulent vaginal discharge and subclinical endometritis had the greatest depressions in measures of fertility at first AI, particularly when subclinical endometritis persisted in the early postpartum period.

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.

Effects of gonadotropin-releasing hormone at initiation of the 5-d timed artificial insemination (AI) program and timing of induction of ovulation relative to AI on ovarian dynamics and fertility of dairy heifers

Two experiments evaluated the effects of the first GnRH injection of the 5-d timed artificial insemination (AI) program on ovarian responses and pregnancy per AI (P/AI), and the effect of timing of the final GnRH to induce ovulation relative to AI on P/AI. In experiment 1, 605 Holstein heifers were synchronized for their second insemination and assigned randomly to receive GnRH on study d 0 (n = 298) or to remain as untreated controls (n = 307). Ovaries were scanned on study d 0 and 5. All heifers received a controlled internal drug-release (CIDR) insert containing progesterone on d 0, a single injection of PGF(2α) and removal of the CIDR on d 5, and GnRH concurrent with timed AI on d 8. Blood was analyzed for progesterone at AI. Pregnancy was diagnosed on d 32 and 60 after AI. Ovulation on study d 0 was greater for GnRH than control (35.4 vs. 10.6%). Presence of a new corpus luteum (CL) at PGF(2α) injection was greater for GnRH than for control (43.1 vs. 20.8%), although the proportion of heifers with a CL at PGF(2α) did not differ between treatments and averaged 87.1%. Progesterone on the day of AI was greater for GnRH than control (0.50 ± 0.07 vs. 0.28 ± 0.07 ng/mL). The proportion of heifers at AI with progesterone <0.5 ng/mL was less for GnRH than for control (73.8 vs. 88.2%). The proportion of heifers in estrus at AI did not differ between treatments and averaged 66.8%. Pregnancy per AI was not affected by treatment at d 32 or 60 (GnRH = 52.5 and 49.8% vs. control = 54.1 and 50.0%), and pregnancy loss averaged 6.0%. Responses to GnRH were not influenced by ovarian status on study d 0. In experiment 2, 1,295 heifers were synchronized for their first insemination and assigned randomly to receive a CIDR on d 0, PGF(2α) and removal of the CIDR on d 5, and either GnRH 56 h after PGF(2α) and AI 16h later (OVS56, n = 644) or GnRH concurrent with AI 72 h after PGF(2α) (COS72; n = 651). Estrus at AI was greater for COS72 than for OVS56 (61.4 vs. 47.5). Treatment did not affect P/AI on d 32 in heifers displaying signs of estrus at AI, but COS72 improved P/AI compared with OVS56 (55.0 vs. 47.6%) in those not in estrus at AI. Similarly, P/AI on d 60 did not differ between treatments for heifers displaying estrus, but CO S72 improved P/AI compared with OVS56 (53.0 vs. 44.7%) in those not in estrus at AI. Administration of GnRH on the first day of the 5-d timed AI program resulted in low ovulation rate and no improvement in P/AI when heifers received a single PGF(2α) injection 5 d later. Moreover, extending the proestrus by delaying the final GnRH from 56 to 72 h concurrent with AI benefited fertility of dairy heifers that did not display signs of estrus at insemination following the 5-d timed AI protocol.

22 INFLUENCE OF SEASONALITY ON OVULATORY FOLLICULAR WAVE DYNAMIC IN LONG PROTOCOLS IN SANTA INÊS SHEEP IN THE TROPICS

This study was designed to investigate the influence of seasonality on ovulatory follicular wave dynamics in long protocols, with or without P4 device replacement, in Santa Inês sheep. Seventy adult ewes were submitted to 2 synchronization protocols in 3 seasons (factorial 2 × 3; non-breeding: G-1CIDR, n = 12 and G-2CIDR, n = 11; transition: G-1CIDR, n = 12 and G-2CIDR, n = 12; breeding: G-1CIDR, n = 11 and G-2CIDR, n = 12). On D0 (randomised day of oestrus cycle), the oestrus was synchronized with a P4 device (CIDR™; Pfizer, New Zealand) for 14 days. However, in G-2CIDR, the CIDR was replaced by a new one on D7. At D0 and 14, 2.5 mg of dinoprost (Lutalyse™, Pfizer, New Zealand), IM, were administered, and on D14, all ewes received 300 IU of eCG (Novormon™, Syntex, Argentina). Ultrasonographic exam was performed daily between D0 and D14 and, every 8 h until D19. Data were analysed by GLIMMIX using SAS (SAS Institute Inc., Cary, NC, USA). There was no interaction between groups and seasons, being presented the main effects for the variables. There were effects of treatment on the day of emergence of an ovulatory wave (G-1CIDR: 8.28 ± 0.54 and G-2CIDR: 9.23 ± 0.44; P = 0.04), maximum diameter of first ovulatory follicle (G-1CIDR: 8.09 ± 0.22 v. G-2CIDR: 7.62 ± 0.19 mm; P = 0.02) and duration of follicular growth (G-1CIDR: 192.00 ± 11.27 v. G-2CIDR: 175.70 ± 9.92 h; P = 0.07). However, there were no effect of treatment on day of ovulation (G-1CIDR: 17.11 ± 0.11 v. G-2CIDR: 17.20 ± 0.10; P = 0.43), ovulatory diameter (G-1CIDR: 7.45 ± 0.21 v. G-2CIDR: 7.34 ± 0.19 mm; P = 0.59), and follicular growth rate (G-1CIDR: 0.69 ± 0.04 v. G-2CIDR: 0.71 ± 0.03 mm day–1; P = 0.65). Effects of season were observed on day of emergence (non-breeding: 7.07 ± 0.641a v. transition: 9.09 ± 0.61b v. breeding: 9.89 ± 0.48b; P < 0.0001), maximum diameter of first ovulatory follicle (non-breeding: 8.28 ± 0.24a v. transition: 7.71 ± 0.26b v. breeding: 7.54 ± 0.21b mm; P = 0.01), ovulatory diameter (non-breeding: 7.70 ± 0.23a v. transition: 7.59 ± 0.26a v. breeding: 6.88 ± 0.21b mm; P = 0.006) and duration of follicular growth (non-breeding: 216.11 ± 12.38a v. transition: 177.38 ± 13.67b v. breeding: 162.57 ± 11.28b h; P = 0.0004). Season had no effect on day of ovulation (non-breeding: 17.15 ± 0.12 v. transition: 17.05 ± 0.14 v. breeding: 17.28 ± 0.11; P = 0.40), and follicular growth rate (non-breeding: 0.66 ± 0.04 v. transition: 0.67 ± 0.05 v. breeding: 0.77 ± 0.04 mm day–1; P = 0.11). Therefore, both protocols showed efficiency in synchronization regardless of the season. Furthermore, protocols and seasons promoted effect on the day of emergence of ovulatory wave, thus influencing the other variables. Supported by FAPESP.

203 EFFECT OF SUPPLEMENTAL FOLLICLE-STIMULATING HORMONE OR EQUINE CHORIONIC GONADOTROPIN DURING THE PROTOCOL FOR TIMED AI IN HIGH-PRODUCING HOLSTEIN COWS

Programs that allow timed AI (TAI) have been used to improve reproductive efficiency in dairy herds; however, in many cases pregnancies per AI (P/AI) during these programs remain suboptimal. In the present experiment, it was hypothesized that treatment with FSH or eCG at the time of the PGF2 treatment of the TAI protocol would increase fertility in dairy cattle. This experiment was performed in June 2008 (winter) and January 2009 (summer) on 2 commercial dairy farms located in southeast Brazil. On a random day of the estrous cycle (Day 0), 694 cows at 196 ± 138 days in milk (DIM) received 2 mg of estradiol benzoate (RICB®, Tecnopec, São Paulo, Brazil) i.m. and a releasing intravaginal device (P4; Primer®, Tecnopec), which was removed on Day 8 when 150 μg of PGF (Prolise®, ARSA, Buenos Aires, Argentina) i.m. were administered. At this time, the cows were stratified by days in milk (DIM), parity, number of insemination, milk production, presence of a CL on Day 0, and body condition score (BCS) and were randomly assigned to 1 of 3 treatments: control (n = 232), consisting of no additional treatment; eCG (n = 232), consisting of 400 IU of eCG (Folligon®, Intervet, São Paulo, Brazil); and FSH (n = 230), consisting of 20 mg of FSH (Folltropin®, Bioniche, Belleville, Ontario, Canada). All cows received GnRH (100 μg of gonadorelin; Fertagyl®, Intervet) and were TAI 56 h after the removal of the device. Pregnancy diagnosis was performed 30 and 60 days after TAI. Also, a subset of animals (n = 89) was submitted to ultrasonographic exams to evaluate the diameter of the ovulatory follicles (ØOF), time to ovulation after P4 removal (TOV), and ovulation rate (OR). Statistical analyses were performed with logistic regression by PROC GLIMMIX of SAS (SAS Institute, Cary, NC, USA). There were no interactions of treatment with DIM, parity, number of insemination, BCS, locomotion score, sire, batch, inseminator, farm, or month; therefore, these variables were removed from the statistical model. The overall P/AI was different between treatments at 30 days after TAI [control = 28.0% (65/232), eCG = 29.7% (69/232), and FSH = 18.7% (43/230); P = 0.01], but not at 60 days [control = 21.6% (50/232), eCG = 24.1% (56/232), and FSH = 16.1% (37/230); P = 0.08]. Pregnancy loss was also similar among treatments [control = 23.1% (15/65), eCG = 18.8% (13/69), and FSH = 14.0% (6/43); P = 0.08]. In addition, the treatments (control, eCG, and FSH, respectively) were not different among ØOF (13.78 ± 0.52; 14.50 ± 0.59; and 15.35 ± 0.69 mm; P = 0.15); TOV (82.50 ± 2.14; 78.48 ± 2.35; and 78.96 ± 2.39 h after P4 withdrawal; P = 0.30); or OR [82.76% (24/29); 83.33% (25/30); and 83.33% (25/30); P = 0.44]. Thus, these data do not indicate a major fertility-enhancing effect of a single eCG or FSH treatment during protocol for TAI in high-producing dairy cows, contrary to the hypothesis of the present study. Tecnopec, Fazenda Campestre, Agrindus S/A, Echoa e Nutricell Nutrientes Celulares.

180 PREGNANCY LOSS (BETWEEN 30 AND 60 DAYS) IN HIGH-PRODUCING REPEAT-BREEDER HOLSTEIN COWS SUBMITTED TO EMBRYO TRANSFER

Reproductive efficiency has a major impact on profitability of dairy farms. Pregnancy loss in cattle is one of the major impediments for adequate reproductive performance. The aim of the present study was to evaluate factors associated with pregnancy loss between 30 and 60 days of gestation in high-producing repeat-breeder (>4 services) Holstein cows submitted to embryo transfer (ET). A retrospective analysis was performed using data from 1 commercial dairy farm, located in Descalvado, Brazil (22°01′27″S; 47°53′19″L). Overall, 2096 ET were analyzed from 2004 to 2008. High-producing Holstein cows from the same herd were used as embryo donors. Embryos were produced by superovulation using the same protocol (8 decreasing injection of FSH) and were transferred, either fresh or frozen-thawed, to repeat-breeder Holstein recipients 6, 7, or 8 days after estrus (synchrony of Day 1, Day 0, or Day 1 with the donor, respectively). Statistical analysis was performed using PROC GLIMMIX of SAS (SAS Institute Inc., Cary, NC, USA). Variables included in the model were synchrony between recipient and donor at ET day, fresh and frozen-thawed embryos, stage of embryo development, and embryo quality. All cows were examined for pregnancy by ultrasonography 23 and 53 days after ET (30 and 60 days of pregnancy). There was no effect of year. The pregnancy loss was greater (P = 0.005) for fresh (22.9%, 141/615) v. frozen-thawed embryos (19.4%, 288/1481). Also, pregnancy loss was influenced (P = 0.002) by the synchrony between recipient and donor at ET day [Day -1:18.3% (53/290); Day 0: 18.9% (233/1234); D1: 24.9% (144/578)]. However, there was no difference in pregnancy loss when the stages of embryo development [morula: 20.7% (295/1428); early blastocyst: 18.9% (67/355); blastocyst: 23.0% (59/256); expanded blastocyst: 14.0% (8/57; P = 0.31)] and embryo quality [grade 1: 17.6% (78/443); grade 2: 20.1% (216/1073); grade 3: 23.3% (135/580); P = 0.31] were compared. In conclusion, pregnancy loss was greater in high-producing repeat-breeder Holstein cows receiving fresh embryos compared to frozen-thawed embryos and when Day 1 recipients were used compared to Day -1 and Day 0. Agrindus S/A.

373 STRATEGIES TO IMPROVE CONCEPTION RATES IN DAIRY HEIFERS INDENTIFIED IN ESTRUS USING TAIL HEAD PAINTING AND INSEMINATED WITH SEXED SEMEN

Two strategies to improve the conception rates in dairy heifers identified in estrus using tail head painting and inseminated with sexed semen were evaluated. In the first trial, the effect of GnRH injection (100 μg of gonadorelin) at estrus on ovarian responses and conception rates (CR) were verified. A total of 413 virgin Jersey heifers 11 to 12 mo of age were used. All heifers were treated with 25 mg of dinoprost tromethamine at the first day of the AI program. All inseminations were performed 12 h after estrus detection using sexed semen (2.1 million sperm) and the estrus was detected based upon removal of tail-head paint. At estrus detection, heifers were randomly assigned to receive GnRH or not (GnRH = 212 and No GnRH = 201). A subset of heifers (GnRH = 70 and No GnRH = 70), was scanned by ultrasound every 12 h after estrus detection until ovulation. The largest follicle diameter at estrus (LF), ovulatory follicular diameter (OF), ovulation rate (OR), interval between beginning of estrus and ovulation (IEO), and the proportion of heifers presenting late ovulation (LO, ovulation occurred with more than 36 h after the beginning of estrus) were recorded. The GnRH did not influence the LF (13.3 ± 0.9 v. 13.4 ± 0.2 mm; P = 0.87), the OF (13.4 ± 0.3 v. 13.9 ± 0.2 mm; P = 0.17), or OR [98.6% (69/70) v. 97.1% (68/70); P = 0.57]. However, GnRH treatment tended to shorten the IEO (29.2 ± 1.1 h v. 32.0 ± 1.3 h; P = 0.07) and reduced the occurrence of LO (2.9% (2/69) v. 16.2% (11/68); P = 0.02). However, GnRH injection did not influence the CR [GnRH = 47.2% (100/212) v. No GnRH = 51.7% (104/201); P = 0.38]. The second trial evaluated the CRin dairy heifers after the use of single or double insemination dose. A total of 576 Jersey heifers receiving first, second, or third insemination services were used. The heifers were assigned according to sire utilized into one of the three groups (Single 12 h, Double 12 h, or Double 12/24 h). In Single 12 h (n = 193) or Double 12 h (n = 193) groups, heifers received one or two insemination doses (2.1 million sperm) of sexed semen 12 h after estrus detection, respectively. The Double 12/24 h (n = 190) group heifers received two doses 12 h apart from each other (first dose at 12 h and second dose at 24 h after estrus detection). Differences were found between the number of AI services (P = 0.004) on the CR [First = 55.3%a (115/208); Second = 46.1%a (94/204); Third = 34.8% (57/165); P = 0.004]. However, there was no effect of treatment on the CR [Single 12 h = 45.1% (87/193); Double 12 h = 44.0% (85/193); Double 12/24 h = 49.5% (94/190); P = 0.51]. In conclusion, the GnRH injection altered the timing of ovulation, but failed to increase the CR. Furthermore, double insemination doses of sexed semen did not influence the CR in dairy heifers. Dalhart Jersey Ranch-TX, USA and Sexing Technologies-SP, Brazil.

266 OVUM PICKUP AND IN VITRO EMBRYO PRODUCTION DURING THE SUMMER: DIFFERENCES BETWEEN HOLSTEIN HEIFERS, HIGH-PRODUCING HOLSTEIN COWS IN PEAK LACTATION, AND REPEAT-BREEDER HOLSTEIN COWS

The association of ovum pickup (OPU) and in vitro embryo production (IVP) has been widely used to improve bovine reproduction. However, previous reports have indicated the occurrence of low fertility associated with summer heat stress. In the present work, we hypothesized that different categories of Holstein cattle [heifers (H), high-producing cows in peak lactation (PL), and repeat-breeders (RB)] would respond differently to OPU and IVP during the summer, because of their different metabolisms. This experiment was conducted on 2 commercial dairy farms in southeast Brazil in summer 2009. Cattle (n = 36/category) started a protocol to synchronize follicular wave emergence: 2 mg of estradiol benzoate (Sincrodiol®, OuroFino, Minas Gerais, Brazil) + 50 mg of progesterone (OuroFino) + 150 μg of D-cloprostenol (Sincrocio®, OuroFino) i.m. + a norgestomet ear implant (Crestar®, Intervet, São Paulo, Brazil) on Day 0, implant removal and OPU on Day 5. Respiration rate (RR), rectal temperature (RT), and cutaneous temperature (CT) were recorded on Day 0. Semen from a single Holstein bull previously tested was used in IVP, and oocytes from slaughterhouse were submitted to IVP as a quality control. Statistical analyses were done using PROC GLIMMIX of SAS (SAS Institute, Cary, NC, USA). The average and maximum environmental temperature and humidity were 30 and 39.8°C and 61 and 88%. Heifers were on average 15.7 months old; PL and RB cows had 112.8 ± 5.4a v. 422.8 ± 27.6b days in milk, milk production of 32.8 ± 0.9a v. 21.7 ± 1.1b kg, and number of insemination of 0.9 ± 0.1a v. 6.8 ± 0.3b; P < 0.0001; mean ± SE). Heifers and cows had different RR (H = 11.2 ± 0.3a, PL = 18.2 ± 0.6b, RB= 18.5 ± 0.4b breaths/min; P < 0.0001), RT (H = 38.7 ± 0.1a, PL = 39.56 ± 0.2b, RB = 39.32 ± 0.1b; P < 0.0001), and CT (H = 31.3 ± 0.2a, PL = 33.2 ± 0.3b, RB = 32.9 ± 0.3b; P < 0.0001). At OPU, heifers had greater number of follicles than PL cows, but they were similar to RB cows (H= 18.5 ± 1.9a, PL = 12.4 ± 1.1b, RB = 17.2 ± 2.0a; P = 0.04). Heifers had also greater number of oocytes (H = 9.6 ± 1.6a, PL = 5.0 ± 0.9b, RB = 8.8 ± 13ab; P = 0.03) and viable oocytes (H = 7.6 ± 1.5a, PL = 3.6 ± 0.8b, RB = 6.8 ± 1.2ab; P = 0.05) recovered from OPU than PL cows and similar to RB cows. However, at IVP, heifers had greater rates than both other categories (cleavage at Day 3: H = 47.8%a, PL = 31.1%b, RB = 35.4%b, P = 0.008; blastocyst at Day 7: H = 21.0%a, PL = 4.1%b, RB = 3.8%b, P < 0.0001) and more grade I embryos (H = 1.3 ± 0.4a, PL = 0.3 ± 0.2b, RB = 0.5 ± 0.2b, P = 0.04). The quality control had 80.7% cleavage and 45.4% blastocyst rates. The differences found among heifers and cows are probably related to their metabolism under heat stress, compromising oocyte number and quality. Also, although RB had similar number of viable oocytes than heifers, these oocytes are probably compromised, leading to poorer results at IVP, as observed. Fazendas Santa Rita e Campestre, Vida Reprodutiva, LMMD, SAMVET, VITROGEN, OuroFino Saúde Animal, FAPESP (proc09/00938-3).

Effect of fixed-time embryo transfer on reproductive efficiency in high-producing repeat-breeder Holstein cows

The aim of the present study was to compare a synchronization of time of ovulation protocol for fixed-timed embryo transfer (FTET) with the usual administration of a single dose of prostaglandin associated with detection of estrus. Also, the effect of the presence of CL at the beginning of FTET protocol was evaluated. Lactating Holstein cows (n=651) with three previous artificial inseminations were classified according to presence or absence of a corpus luteum (CL). Cows with a CL were randomly assigned to two additional treatments and submitted to embryo transfer after detection of estrus (PGF-Estrus) or FTET (FTET-CL). Cows without CL were allocated to the FTET-NoCL treatment. On a random day of the estrous cycle (Day 0), cows in the PGF-Estrus treatment (n=229) were treated with 150 microg d-cloprostenol (PGF) i.m. followed by detection of estrus from Day 1 through Day 5 after PGF. Embryos were transferred 6-8 days after estrus detection. Cows in the FTET-CL (n=208; presence of CL) and FTET-NoCL (n=214; absence of CL) treatments received a norgestomet ear implant plus 2mg estradiol benzoate (EB) and 50mg progesterone i.m. on Day 0. On Day 8, the implant was removed and 400 IUeCG, 150 microg d-cloprostenol and 1mg estradiol cypionate i.m. were administered. No detection of estrus was performed and Day 10 was arbitrarily considered as the estrus day. Ultrasonographic exams were performed in all recipients and only cows with a single CL> or =15 mm or multiple CL received a fresh or frozen-thawed embryo on Day 17. Pregnancy was diagnosed by ultrasonography at 30 and 60 days of pregnancy. When FTET and PGF-Estrus were compared, the proportion of cows receiving an embryo (recipients transferred-to-treated rate) was greater in the FTET-CL (75.0% (156/208) than in PGF-Estrus (34.5%, 79/229; P<0.0001) treatment. Pregnancy rate (60 days) was also greater in FTET-CL (29.3%, 61/208) when compared to PGF-Estrus (16.2%, 37/229; P=0.001). However, no differences were found in pregnancy loss [PGF-Estrus=11.9% (5/42), FTET-CL=9.0% (6/67); P=0.62] and circulating progesterone concentration at embryo transfer [PGF-Estrus=4.02+/-0.52 ng/mL (n=25), FTET-CL=3.33+/-0.32 ng/mL (n=27); P=0.25] among these treatments. The presence of CL at the beginning of FTET protocol resulted greater transferred-to-treated rate [FTET-CL=75.0% (156/208) vs. FTET-NoCL=61.2% (131/214); P=0.003], but showed no effect on pregnancy rate at 60 days [FTET-CL=29.3% (61/208) vs. FTET-NoCL=22.9% (49/214); P=0.13], pregnancy loss [FTET-CL=9.0% (6/67) vs. FTET-NoCL=2.0% (1/50); P=0.15] and circulating progesterone concentration at ET [FTET-CL=3.33+/-0.32 ng/mL (n=27) compared to FTET-NoCL=3.44+/-0.40 ng/mL (n=2 9); P=0.82]. In conclusion, the protocol for synchronization of time of ovulation using norgestomet ear implant, EB and eCG increased recipients transferred-to-treated and pregnancy rates in high-producing repeat-breeder Holstein cows. Also, recipients without CL at the beginning of the time of ovulation synchronization treatment resulted in similar pregnancy rate as recipients with CL submitted to FTET protocol. Thus, the suggested protocol allowed the performance of FTET, without the need for detection of estrus, simplifying the reproductive management and increasing the reproductive efficiency in repeat-breeder Holstein recipients.

Comparison of gonadorelin products in lactating dairy cows: efficacy based on induction of ovulation of an accessory follicle and circulating luteinizing hormone profiles

This 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) > or =15 mm and at least one follicle > or =10mm, were evaluated for response to GnRH treatment. Selected cows were randomized to receive (100 microg; 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 microg (n=10 per group) or 50 microg (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 microg than in those treated with 50 microg, 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.

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.

251 FOLLICLE DEVIATION AND OVULATORY CAPACITY IN BOS INDICUS HEIFERS

In Holstein cows, the diameter of the dominant follicle (DF) at the time of follicle deviation is 8.5 mm and the subordinate follicle (SF) is 7.2 mm (Ginther et al. 1996 Biol. Reprod. 55, 1187–1194). However, follicular responsiveness to an ovulatory treatment occurs only with 10.0-mm-diameter follicles (Sartori et al. 2001 Biol. Reprod. 65, 1403–1409). The current study tested the hypothesis that, in Bos indicus (Nelore and crossbred Nelore � Gir) females, the follicular diameters at the time of deviation and ovulation responsiveness are smaller than those in Holstein cows. The experiment was performed in two phases. In the first phase, 12 Nelore heifers were previously synchronized with a protocol using progestagen and estradiol benzoate. After implant removal, all heifers were evaluated by transrectal ultrasonography (Aloka SSD-500, Tokyo, Japan) every 12 h until Day 5 of the estrous cycle (Day 0 = Day of the ovulation) to assess the time of ovulation, the time of follicle deviation, and the follicular diameter at the deviation. In the second phase, 29 Bos indicus heifers (Nelore and crossbred Nelore � Gir) were previously synchronized with the same protocol as cited above. After the ovulations (Day 0), the follicles were evaluated by transrectal ultrasonography every 24 h, until they reached the diameter of 7.0–8.4 mm (n = 9); 8.5–10.0 mm (n = 10); and &gt;10.0 mm (n = 10). In order to assess the ovulatory capacity, all animals were treated with 25 mg of LH (Lutropin-V�; Bioniche Animal Health, Inc., Belleville, Ontario, Canada) at these follicle diameter ranges. After the LH treatment, all animals were monitored by ultrasonography every 12 h for 48 h. ANOVA, Bartlett, and chi-square tests were used in the statistical analyses. In the first phase, the diameters of the DF and SF at the time of follicular deviation (61.9 � 4.9 h after ovulation) were 6.2 � 0.2 and 5.8 � 0.2 mm, respectively. In the second phase, the the average follicular diameters at the time of LH administration in the groups 7.0–8.4 mm, 8.5–10.0 mm, and &gt;10.0 mm were 7.6a � 0.1 mm, 9.6b � 0.1 mm, and 10.9c � 0.2 mm; and their ovulation rates were 33.3%a (3/9), 80.0%b (8/10), and 90.0%b (9/10), respectively (P &lt; 0.05). The interval from LH treatment to ovulation was 38.0 � 4.0 h, 31.5 � 2.7 h, and 30.0 � 2.0 h, respectively (P &gt; 0.05). In conclusion, in Bos indicus heifers, follicle deviation occurred with smaller diameters than previously reported in Bos taurus breeds. In addition, Bos indicus heifers are able to ovulate in response to 25 mg of LH with smaller diameters compared to those of Bos taurus breeds. Moreover, in Bos indicus heifers, ovulatory capacity is acquired by follicles as small as 7.0–8.4 mm, but this responsiveness significantly increases after follicles reach 8.5–10.0 mm. This work was supported by FAPESP (Proc:03/10203-4); Bioniche Animal Health, Inc., Belleville, Ontario, Canada; and Tecnopec, S�o Paulo, Brazil.

387 EFFECT OF NUMBER OF INSEMINATIONS ON EMBRYO PRODUCTION IN SUPERSTIMULATED NELORE (BOS INDICUS) COWS SUBJECTED TO FIXED-TIME ARTIFICIAL INSEMINATION

In embryo transfer programs, 2 inseminations per superstimulated donor are usually recommended. Based on studies of follicular dynamics in Bos indicus donors (Baruselli et al. 2006 Theriogenology 65, 77–88), we tested the hypothesis that a single fixed-time AI (FTAI) at 16 h after pituitary luteinizing hormone (pLH) treatment is as efficacious as 2 FTAI at 12 and 24 h after the pLH treatment. Suckling Nelore cows (n = 10), 60 � 12 days postpartum, were equally distributed in 2 experimental groups: G-1TAI vs. G-2TAI, in a crossover design. All animals received an intravaginal progesterone device (DIB; Syntex S.A., Buenos Aires, Argentina) and 2 mg of estradiol benzoate (IM, Ric Be; Syntex) at random stages of the estrous cycle (Day 0). Superstimulatory treatments started on Day 4 with pFSH (133 mg; Folltropin-V; Bioniche Animal Health Canada, Inc., Belleville, Ontario, Canada) in 8 decreasing doses, given IM 12 h apart. On Day 6, all cows received 2 (AM and PM) treatments of 0.15 mg of d-cloprostenol (Prolise; Syntex). The DIB devices were removed 36 h after the first PGF2� injection. The pLH treatment (25 mg IM; Lutropin-V; Bioniche) was given 48 h after the first PGF2� treatment (12 h after the last pFSH treatment). In the G-2TAI group, all cows received 2 inseminations (12 and 24 h after the pLH). Cows in the G-1TAI group received a single insemination (16 h after the pLH). All inseminations were done with the same batch of semen from a single bull. Ultrasound examinations (PIE Medical Scanner 200; Pie Medical Equipment, Maastricht, The Netherlands) were performed every 12 h from 0 to 72 h after pLH treatment to evaluate the number of ovulatory follicles (&lt;8 mm), the ovulation rate, and the time of ovulation. Variables were analyzed by ANOVA and chi-square test. The homogeneity of the variances (distribution of ovulations) was analyzed by Bartlett&apos;s test. Conclusions were based on a 5% level of significance. The results for G-1TAI and G-2TAI were, respectively: number of follicles &gt;8 mm at the time of pLH administration (16.2 � 1.4 vs. 14.8 � 1.2; P &gt; 0.05), ovulation rate (63.8 � 3.8% vs. 64.2 � 4.3%; P &gt; 0.05), interval from the first to the last ovulation (32.4 � 1.8 vs. 33.6 � 1.6 h; P &gt; 0.05), total ova/embryos (8.2 � 0.9 vs. 7.2 � 0.8; P &gt; 0.05), Grade 1 embryos (2.0 � 0.5 vs. 2.3 � 0.4; P &gt; 0.05), transferable embryos (Grades 1, 2, and 3) (4.3 � 0.7 vs. 4.2 � 0.6; P &gt; 0.05), freezable embryos (Grades 1 and 2) (2.9 � 0.6 vs. 2.8 � 0.4; P &gt; 0.05), unfertilized ova (0.6 � 0.2 vs. 0.8 � 0.2; P &gt; 0.05), and degenerated embryos (3.3 � 0.9 vs. 2.2 � 0.3; P &gt; 0.05). These results suggest no significant differences in embryo production between superstimulated Nelore donors inseminated once or twice by fixed time following administration of pLH. This work was supported by Tecnopec, Brazil.

363 EFFECT OF OESTRADIOL VALERATE OR BENZOATE ON INDUCTION OF A NEW FOLLICULAR WAVE EMERGENCE IN BOS INDICUS COWS AND HEIFERS TREATED WITH NORGESTOMET AURICULAR IMPLANT

Estradiol given during progestin-treatment promotes emergence of a new follicular wave in cattle. The interval from estradiol treatment to follicular wave emergence is dependent on the estradiol preparation, the dose, and possibly the animal category (cows or heifers). Therefore, this experiment aimed to compare the effects of either estradiol benzoate (EB) or estradiol valerate (EV) on the synchrony of ovarian follicular wave emergence in Bos indicus (Nelore) heifers and cows treated with a Norgestomet implant (Crestar�; Intervet, Boxmeer, The Netherlands; factorial 3 � 2 design). Lactating cows (n = 30; 70-90 days postpartum) and cycling heifers (n = 29) were homogeneously assigned, according to the presence of corpora lutea, to six experimental groups (G2EB, G2.5EV, and G5EV for each animal category). At random stages of the estrous cycle (Day 0), the females received an auricular implant and were assigned to receive 2 mg of EB (Farmavet, S�o Paulo, Brazil; 10 cows and 10 heifers; G2EB), 2.5 mg of EV plus 1.5 mg of Norgestomet (10 cows and 10 heifers; G2.5EV; half of a recommended dose), or 5 mg of EV plus 3 mg of Norgestomet (10 cows and 10 heifers; G5EV, full recommended dose) i.m. Transrectal ultrasonography was performed once daily from Day 0 to confirm the follicular dominance (new growing dominant follicle >8 mm in diameter). The day of wave emergence was retrospectively defined as the day when the dominant follicle was first detected at a diameter of 3 mm. Two-way analysis of variance was used to compare the effects of treatments (G2EB, G2.5EV, and G5EV), category (cows and heifers), and the treatments-by-category interaction on the interval from beginning of the treatment to wave emergence. The LSD was used to locate differences among groups and the Bartlett's test revealed heterogeneity of variance. Statistical analysis was conducted by SAS for Windows (SAS Institute, Inc., Cary, NC, USA). There was a significant effect of treatment and category (P < 0.001), but there were no treatments-by-category interactions (P > 0.05). A new follicular wave was induced in all animals after treatment with EB or EV. The heifers given G2EB (2.50 � 0.19a; 2 to 3x days) had a reduced (P < 0.01) and least variable interval (P < 0.05) than those given G2.5EV (4.20 � 0.27b; 3 to 6xy days) or G5EV (6.10 � 0.57c; 3 to 8y days). The cows given G5EV (4.00 � 0.52b; 2 to 6y days) had the longest (P = 0.05) and more variable interval (P < 0.001) than those given G2EB (2.50 � 0.22a; 2 to 4x days), but were similar to those given G2.5EV (3.10 � 0.41ab; 2 to 6xy days). The effect of EB was similar in heifers and cows (P > 0.05); however, the EV or 2.5EV promoted a longer emergence wave interval in the heifers than in the cows (P < 0.05). Analyzing the main effects, cows and heifers given G2EB (2.50 � 0.15a; 2 to 4x days) had a smaller and less variable interval than those given G2.5EV (3.65 � 0.27b; 2 to 6y) or G5EV (5.05 � 0.44c; 2 to 8z). In conclusion, the EV treatment, in both doses (5 or 2.5 mg), resulted in a delayed and more variable interval to emergence of a new follicular wave than 2 mg of EB in Bos indicus cows and heifers treated with a Norgestomet auricular implant. This work was supported by Intervet, Brazil.

Allelic variation in Streptococcus pneumoniae autolysin (N-acetyl muramoyl-L-alanine amidase)

The lytA gene encoding the autolysin of Streptococcus pneumoniae may be a virulence determinant. Single-strand conformational polymorphism analysis demonstrated heterogenicity throughout the gene in clinical isolates and strains from the clonal serotypes 7 and 14. Sequence analysis of part of the choline-binding domain showed that in two isolates four amino acid substitutions occurred.