Neither plasma progesterone concentrations nor exogenous eCG affects rates of ovulation or pregnancy in fixed-time artificial insemination (FTAI) protocols for puberal Nellore heifers

The objective was to evaluate the effects of plasma progesterone (P4) concentrations and exogenous eCG on ovulation and pregnancy rates of pubertal Nellore heifers in fixed-time artificial insemination (FTAI) protocols. In Experiment 1 (Exp. 1), on Day 0 (7 d after ovulation), heifers (n = 15) were given 2 mg of estradiol benzoate (EB) im and randomly allocated to receive: an intravaginal progesterone-releasing device containing 0.558 g of P4 (group 0.5G, n = 4); an intravaginal device containing 1 g of P4 (group 1G, n = 4); 0.558 g of P4 and PGF2α (PGF; 150 μg d-cloprostenol, group 0.5G/PGF, n = 4); or 1 g of P4 and PGF (group 1G/PGF, n = 3). On Day 8, PGF was given to all heifers and intravaginal devices removed; 24 h later (Day 9), all heifers were given 1 mg EB im. In Exp. 2, pubertal Nellore heifers (n = 292) were treated as in Exp. 1, with FTAI on Day 10 (30 to 36 h after EB). In Exp. 3, pubertal heifers (n = 459) received the treatments described for groups 0.5G/PGF and 1G/PGF and were also given 300 IU of eCG im (groups 0.5G/PGF/eCG and 1G/PGF/eCG) at device removal (Day 8). In Exp. 1, plasma P4 concentrations were significantly higher in heifers that received 1.0 vs 0.588 g P4, and were significantly lower in heifers that received PGF on Day 0. In Exp. 2 and 3, there were no significant differences among groups in rates of ovulation (65-77%) or pregnancy (Exp. 2: 26-33%; Exp. 3: 39-43%). In Exp. 3, diameter of the dominant ovarian follicle on Day 9 was larger in heifers given 0.558 g vs 1.0 g P4 (10.3 ± 0.2 vs 9.3 ± 0.2 mm; P < 0.01). In conclusion, lesser amounts of P4 in the intravaginal device or PGF on Day 0 decreased plasma P4 from Days 1 to 8 and increased diameter of the dominant follicle on Day 9. However, neither of these nor 300 IU of eCG on Day 8 significantly increased rates of ovulation or pregnancy. © 2011.

Impact of Probing the Reproductive Tract During Early Pregnancy on Fertility of Beef Cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Impact of the temperament of Nellore cows on the quality of handling and pregnancy rates in fixed-time artificial insemination

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Supplementation with sunflower seed increases circulating cholesterol concentrations and potentially impacts on the pregnancy rates in Bos indicus beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The association between follicular size at time of spontaneous rupture and pregnancy rates in clomiphene citrate treated PCOS patients in coit cycles

Objective: To investigate the follicular size at spontaneous rupture on pregnancy rate in patientswith polycystic ovary syndrome (PCOS) undergoing clomiphene citrate (CC) ovulation.Design: Cross-sectional study.Patients and methods: One hundred and four women with ovulatory cycles after use of CCfollowed by ultrasound to determine the follicle size at the time of rupture, which wassubsequently correlated with the occurrence of pregnancy or not in coit cycles.Results: In the group of follicular rupture at a mean diameter25 mm (n¼54), pregnancy ratewas 35.1% and when follicular rupture occurred at a mean diameter425 mm (n¼50), it was34% (p40.05). When different diameters at follicular rupture were randomly correlated with thepregnancy rate, there was no significant difference.Conclusion: Our data suggest that the occurrence of pregnancy after ovulation induction withCC in women with PCOS is not associated with follicle size at the time of rupture.

Minimal and mild endometriosis negatively impact on pregnancy outcome

Endometriosis, a highly prevalent gynecological disease, can lead to infertility in moderate to severe cases. Whether minimal stages are associated with infertility is still unclear. The purpose of this systematic review is to present studies regarding the association between pregnancy rates and the presence of early stages of endometriosis. Studies regarding infertility, minimal (stage I, American Society of Reproductive Medicine [ASRM]) and mild (stage II, ASRM) endometriosis were identified by searching on the MEDLINE database from 1985 to September 2011 using the following MESH terms: endometriosis; infertility; minimal; mild endometriosis; pregnancy rate. 1188 articles published between January of 1985 and November of 2011 were retrieved; based on their titles, 1038 citations were excluded. Finally, after inclusion and exclusion criteria, 16 articles were selected to be part of this systematic review. Several reasons have been discussed in the literature to explain the impact of minimal endometriosis on fertility outcome, such as: ovulatory dysfunction, impaired folliculogenesis, defective implantation, decrease embryo quality, abnormal immunological peritoneal environment, and luteal phase problems. Despite the controversy involving the topic, the largest randomized control trial, published by Marcoux et al. in 1997 found a statistically different pregnancy rate after resection of superficial endometrial lesions. Earlier stages of endometriosis play a critical role in infertility, and most likely negatively impact pregnancy outcomes. Further studies into stage I endometriosis, especially randomized controlled trials, still need to be conducted.

Conception Rate Using the Select-Synch Protocol in Combination with a Lower Dose Progesterone-Releasing Intravaginal Insert (1.38 g) in Swiss Dairy Cows

Background: Synchronization programs have become standard in the dairy industry. In Switzerland, these programs are used but newly. The objective of this study was A) to estimate the pregnancy rate after a Select-Synch protocol in- cluding a low dosage of progesterone in CIDR (1.38 g). As a second step B) this pregnancy rate should be compared to cows from another Swiss study that used a Select-Synch protocol with the 1.9 g insert (Rudolph et al., 2011). Methods: A) 196 cows were included in the study. Cows received a CIDR 1.38 g and 2.5 ml of buserelin i.m. on d 0. On d 7, the CIDR insert was removed and 5 ml of dinoprost was administered i.m. On d 0 a milk sample for progesterone analysis was taken. Pregnancy was determined at or more than 35 days after artificial insemination. B) The 1.38 g group and the 1.9 g group were compared as to cow and farm factors, number of preceding AI’s, gynecological and uterine pretreat- ment and treatment itself. A forward selection procedure was used (test result considered significant if p-value  0.05). Results: A) The pregnancy rate, using the Select-Synch protocol with the CIDR 1.38 g was 44.4%. B) The CIDR 1.9 g Select-Synch group revealed a pregnancy rate of 50.4% (Rudolph et al., 2011). Significant differences between the groups were not found. Conclusion: The 1.38 g CIDR-Select-Synch protocol may be recommended for multiparous dairy cows. The pregnancy rate compared to the 1.9 g CIDR-Select-Synch protocol was 8% lower, but this difference was not significant.

Latino Teen Pregnancy in Texas: Prevalence, Prevention, and Policy

Texas is home to over one million Latino teens who are at risk for negative reproductive health outcomes, such as teen pregnancy and STIs. Teen pregnancy disproportionately impacts the health of Latino teens in Texas and places them at risk of continued high rates of poverty, school dropout, and unemployment unless Texas makes a concerted effort to reduce its teen pregnancy rate. The birth rate among Latina girls is astonishing: 98 per 1000 Latinas (aged 15-19) are giving birth. This translates to over 32,000 births each year among Latina teens, costing almost $98 million in direct medical expenditures and well over $638 million if other costs are included. Most teens become sexually experienced while they are of school age, which translates to an estimated 414,583 sexually experienced Latino students attending Texas public schools. Of these Latino youth, 237,466 report being currently sexually active, and 89,000 report having had four or more sexual partners in their lifetime. While causes of teen pregnancy are complex, the solutions to teen pregnancy are known. Texas needs an effective, comprehensive approach to address the sexual health needs of Texas Latino youth that includes: statewide implementation and monitoring of evidence-based sex education for middle school and high school students, access to reproductive health services for students who are already sexually experienced, and widespread training on adolescent sexual health for teachers, service providers, and parents. By tackling teen pregnancy, we can positively impact the future and well-being of not only Latinos, but of all Texans, and subsequently can contribute to the social and economic success of Texas.

Does Immediate Access to Birth Control Help Prevent Pregnancy? A Comparison of Onsite Provision Versus Off Campus Referral for Contraception at Two School-Based Clinics

PURPOSE: The purpose of this study was to assess the impact of different policies on access to hormonal contraception and pregnancy rates at two high school-based clinics. METHODS: Two clinics in high schools (Schools A and B), located in a large urban district in the southwest US, provide primary medical care to enrolled students with parental consent; the majority of whom have no health insurance coverage. The hormonal contraceptive dispensing policy of at School clinic A involves providing barrier, hormonal and emergency contraceptive services on site. School clinic B uses a referral policy that directs students to obtain contraception at an off-campus affiliated family planning clinic. Baseline data (age, race and history of prior pregnancy) on female students seeking hormonal contraception at the two clinics between 9/2008-12/2009 were extracted from an electronic administrative database (AHLERS Integrated System). Data on birth control use and pregnancy tests for each student was then tracked electronically through 3/31/2010. The outcomes measures were accessing hormonal contraception and positive pregnancy tests at any point during or after birth control use were started through 12/2009. The appointment keeping rate for contraceptive services and the overall pregnancy rates were compared between the two schools. In addition the pregnancy rates were compared between the two schools for students with and without a prior history of pregnancy. RESULTS: School clinic A: 79 students sought hormonal contraception; mean age 17.5 years; 68% were > 18 years; 77% were Hispanic; and 20% reported prior pregnancy. The mean duration of the observation period was 13 months (4-19 months). All 79 students received hormonal contraception (65% pill and 35% long acting progestin injection) onsite. During the observation period, the overall pregnancy rate was 6% (5/79); 4.7% (3/63) among students with no prior pregnancy. School clinic B: 40 students sought hormonal contraception; mean age 17.5 years; 52% > 18 years; 88 % were Hispanic; and 7.5% reported prior pregnancy. All 40 students were referred to the affiliated clinic. The mean duration of the observation period was 11.9 months (4-19 months). 50% (20) kept their appointment. Pills were dispensed to 85% (17/20) and 15% (3/20) received long acting progestin injection. The overall pregnancy rate was 20% (8/40); 21.6% (8/37) among students with no prior pregnancy. A significantly higher frequency of students seeking hormonal contraception kept their initial appointment for birth control at the school dispensing onsite contraception compared to the school with a referral policy for contraception (p<0.05). The pregnancy rate was significantly higher for the school with a referral policy for contraception compared to the school with onsite contraceptive services (p< 0.05). The pregnancy rate was also significantly higher for students without a prior history of pregnancy in the school with a referral policy for contraception (21.6%) versus the school with onsite contraceptive services (4.7%) (p< 0.05). CONCLUSION: This preliminary study showed that School clinic B with a referral policy had a lower appointment keeping rate for contraceptive services and a higher pregnancy rate than School clinic A with on-site contraceptive services. An on-site dispensing policy for hormonal contraceptives at high school-based health clinics may be a convenient and effective approach to prevent unintended first and repeat pregnancies among adolescents who seek hormonal contraception. This study has strong implications for reproductive health policy, especially as directed toward high-risk teenage populations.

Modified natural cycle in vitro fertilization an alternative in vitro fertilization treatment with lower costs per achieved pregnancy but longer treatment time

OBJECTIVE To analyze the cost and time requirement per achieved pregnancy in optimized modified natural cycle in vitro fertilization (mNC-IVF) based on a treatment protocol with very few consultations and to compare those with conventional gonadotropin-stimulated aVF (clVF) cycles. STUDY DESIGN Mono centric prospective trial. Eighty infertile patients each received 1 modified mNC-IVF cycle using low doses of the clomiphene citrate. Based on the number of consultations and the clinical pregnancy rate per cycle, the total costs and required time to achieve a pregnancy were analyzed and compared with cIVF. Calculations for cIVF were based on standard therapy protocols and outcomes of European registries. RESULTS Patients (21-42 years old, 35.4 +/- 4.7 years) undergoing mNC-IVF required on average 1.2 consultations before follicle aspiration. Pregnancy rate per transfer and per initiated cycle were 25% and 13.6%, respectively. Multiple pregnancies did not occur. According to the calculations, total costs per pregnancy rate were around 15% lower with mNC-IVF as compared to cIVF. In contrast, time to achieve an equal pregnancy rate was calculated to take around 30% longer with mNC-IVF as compared to cIVF. CONCLUSION mNC-IVF using very low dosages of clomiphene citrate avoids multiple pregnancies and is less expensive but more time consuming per achieved pregnancy when compared to clVF.

African American female adolescents and antecedents of pregnancy

Although the pregnancy rate of teenage girls in the United States has decreased in recent years, African American female adolescents still have one of the highest teen pregnancy rates among girls in the United States. Previous studies report inconsistent relationships between adolescent pregnancy and self-esteem and parental communication, caring, and closeness. The purpose of this study was to assess relationships between pregnancy among African American female adolescents (7th to 12th grades) and self-esteem, communication levels and type of relationships with their parents. This study used data collected from The National Longitudinal Study of Adolescent Health (Add Health). Logistic regression analysis was used to determine if the independent variables of self-esteem, levels of parental caring and closeness and levels of communication with parents predicted the dependent variable of pregnancy. After controlling for age and levels of parental education, self-esteem was the only statistically significant variable that was associated with pregnancy. The findings of this study indicate that levels of self-esteem should be further investigated and that self-esteem may be an important factor when designing interventions to prevent adolescent pregnancy, particularly for African American females. ^

Microbial colonisation of human follicular fluid and adverse in vitro fertilisation outcomes

This study, investigating 263 women undergoing trans-vaginal oocyte retrieval for in vitro fertilisation (IVF) found that microorganisms colonising follicular fluid contributed to adverse IVF (pre-implantation) and pregnancy (post-implantation) outcomes including poor quality embryos, failed pregnancy and early pregnancy loss (< 37 weeks gestation). Some microorganisms also showed in vitro growth patterns in liquid media that appeared to be enhanced by the hormonal stimulation protocol used for oocyte retrieval. Elaborated cytokines within follicular fluid were also associated with adverse IVF outcomes. This study is imperative because infertility affects 16% of the human population and the numbers of couples needing assistance continues to increase. Despite significant improvements in the technical aspects of assisted reproductive technologies (ART), the live birth rate has not increased proportionally. Overt genital tract infection has been associated with both infertility and adverse pregnancy outcomes (including miscarriage and preterm birth) as a direct result of the infection or the host response to it. Importantly, once inflammation had become established, medical treatment often failed to prevent these significant adverse outcomes. Current evaluations of fertility focus on the ovary as a site of steroid hormone production and ovulation. However, infertility as a result of subclinical colonisation of the ovary has not been reported. Furthermore, identification of the microorganisms present in follicular fluid and the local cytokine profile may provide clinicians with an early indication of the prognosis for IVF treatment in infertile couples, thus allowing antimicrobial treatment and/or counselling about possible IVF failure. During an IVF cycle, multiple oocytes undergo maturation in vivo in response to hormonal hyperstimulation. Oocytes for in vitro insemination are collected trans-vaginally. The follicular fluid that bathes the maturing oocyte in vivo, usually is discarded as part of the IVF procedure, but provides a unique opportunity to investigate microbial causes of adverse IVF outcomes. Some previous studies have identified follicular fluid markers that predict IVF pregnancy outcomes. However, there have not been any detailed microbiological studies of follicular fluid. For this current study, paired follicular fluid and vaginal secretion samples were collected from women undergoing IVF cycles to determine whether microorganisms in follicular fluid were associated with adverse IVF outcomes. Microorganisms in follicular fluid were regarded as either "colonisers" or "contaminants"; colonisers, if they were unique to the follicular fluid sample, and contaminants if the same microorganisms were detected in the vaginal and follicular fluid samples indicating that the follicular fluid was merely contaminated during the oocyte retrieval process. Quite unexpectedly, by these criteria, we found that follicular fluid from approximately 30% of all subjects was colonised with bacteria. Fertile and infertile women with colonised follicular fluid had decreased embryo transfer rates and decreased pregnancy rates compared to women with contaminated follicular fluids. The observation that follicular fluid was not always sterile, but contained a diverse range of microorganisms, is novel. Many of the microorganisms we detected in follicular fluid are known opportunistic pathogens that have been detected in upper genital tract infections and are associated with adverse pregnancy outcomes. Bacteria were able to survive for at least 28 weeks in vitro, in cultures of follicular fluid. Within 10 days of establishing these in vitro cultures, several species (Lactobacillus spp., Bifidobacterium spp., Propionibacterium spp., Streptococcus spp. and Salmonella entericus) had formed biofilms. Biofilms play a major role in microbial pathogenicity and persistence. The propensity of microbial species to form biofilms in follicular fluid suggests that successful treatment of these infections with antimicrobials may be difficult. Bifidobacterium spp. grew, in liquid media, only if concentrations of oestradiol and progesterone were similar to those achieved in vivo during an IVF cycle. In contrast, the growth of Streptococcus agalactiae and Escherichia coli was inhibited or abolished by the addition of these hormones to culture medium. These data suggest that the likelihood of microorganisms colonising follicular fluid and the species of bacteria involved is influenced by the stage of the menstrual cycle and, in the case of IVF, the nature and dose of steroid hormones administered for the maturation of multiple oocytes in vivo. Our findings indicate that the elevated levels of steroid hormones during an IVF cycle may influence the microbial growth within follicular fluid, suggesting that the treatment itself will impact on the microflora present in the female upper genital tract during pre-conception and early post-conception phases of the cycle. The effect of the host immune response on colonising bacteria and on the outcomes of IVF also was investigated. White blood cells reportedly compose between 5% and 15% of the cell population in follicular fluid. The follicular membrane is semi-permeable and cells are actively recruited as part of the normal menstrual cycle and in response to microorganisms. A previous study investigated follicular fluid cytokines from infertile women and fertile oocyte donors undergoing IVF, and concluded that there were no significant differences in the cytokine concentrations between the two groups. However, other studies have reported differences in the follicular fluid cytokine levels associated with infertile women with endometriosis or polycystic ovary syndrome. In this study, elevated levels of interleukin (IL)-1 á, IL-1 â and vascular endothelial growth factor (VEGF) in vaginal fluid were associated with successful fertilisation, which may be useful marker for successful fertilisation outcomes for women trying to conceive naturally or prior to oocyte retrieval for IVF. Elevated levels of IL-6, IL-12p40, granulocyte colony stimulating factor (GCSF) and interferon-gamma (IFN ã) in follicular fluid were associated with successful embryo transfer. Elevated levels of pro-inflammatory IL-18 and decreased levels of anti-inflammatory IL-10 were identified in follicular fluid from women with idiopathic infertility. Successful fertilisation and implantation is dependent on a controlled pro-inflammatory environment, involving active recruitment of pro-inflammatory mediators to the genital tract as part of the menstrual cycle and early pregnancy. However, ongoing pregnancy requires an enhanced anti-inflammatory environment to ensure that the maternal immune system does not reject the semi-allergenic foetus. The pro-inflammatory skew in the follicular fluid of women with idiopathic infertility, correlates with normal rates of fertilisation, embryo discard and embryo transfer, observed for this cohort, which were similar to the outcomes observed for fertile women. However, their pregnancy rate was reduced compared to fertile women. An altered local immune response in follicular fluid may provide a means of explaining infertility in this cohort, previously defined as 'idiopathic'. This study has found that microorganisms colonising follicular fluid may have contributed to adverse IVF and pregnancy outcomes. Follicular fluid bathes the cumulus oocyte complex during the in vivo maturation process, and microorganisms in the fluid, their metabolic products or the local immune response to these microorganisms may result in damage to the oocytes, degradation of the cumulus or contamination of the IVF culture system. Previous studies that have discounted bacterial contamination of follicular fluid as a cause of adverse IVF outcomes failed to distinguish between bacteria that were introduced into the follicular fluid at the time of trans-vaginal oocyte retrieval and those that colonised the follicular fluid. Those bacteria that had colonised the fluid may have had time to form biofilms and to elicit a local immune response. Failure to draw this distinction has previously prevented consideration of bacterial colonisation of follicular fluid as a cause of adverse IVF outcomes. Several observations arising from this study are of significance to IVF programs. Follicular fluid is not always sterile and colonisation of follicular fluid is a cause of adverse IVF and pregnancy outcomes. Hormonal stimulation associated with IVF may influence whether follicular fluid is colonised and enhance the growth of specific species of bacteria within follicular fluid. Bacteria in follicular fluid may form biofilms and literature has reported that this may influence their susceptibility to antibiotics. Monitoring the levels of selected cytokines within vaginal secretions may inform fertilisation outcomes. This study has identified novel factors contributing to adverse IVF outcomes and that are most likely to affect also natural conception outcomes. Early intervention, possibly using antimicrobial or immunological therapies may reduce the need for ART and improve reproductive health outcomes for all women.

Simulation of the supply capability of sheep on the Mitchell grass downs of north west Queensland

Sheep in western Queensland have been predominantly reared for wool. When wool prices became depressed interest in the sheep meat industry, increased. For north west Queensland producers, opportunities may exist to participate in live sheep and meat export to Asia. A simulation model was developed to determine whether this sheep producing area has the capability to provide sufficient numbers of sheep under variable climatic conditions while sustaining the land resources. Maximum capacity for sustainability of resources (as described by stock numbers) was derived from an in-depth study of the agricultural and pastoral potential of Queensland. Decades of sheep production and climatic data spanning differing seasonal conditions were collated for analysis. A ruminant biology model adapted from Grazplan was used to simulate pregnancy rate. Empirical equations predict mortalities, marking rates, and weight characteristics of sheep of various ages from simple climatic measures, stocking rate and reproductive status. The initial age structure of flocks was determined by running the model for several years with historical climatic conditions. Drought management strategies such as selling a proportion of wethers progressively down to two-tooth and oldest ewes were incorporated. Management decisions such as time of joining, age at which ewes were cast-for-age, wether turn-off age and turning-off rate of lambs vary with geographical area and can be specified at run time. The model is run for sequences of climatic conditions generated stochastically from distributions based on historical climatic data correlated in some instances. The model highlights the difficulties of sustaining a consistent supply of sheep under variable climatic conditions.

Neospora caninum and reproductive wastage in extensively managed Queensland beef herds

Objective To compare reproduction in extensively managed, tropically adapted beef cows that were either seropositive or seronegative to Neospora caninum. Design Longitudinal study of cows within management groups. Methods Compare pregnancy with weaning outcomes for 502 seropositive and 3255 seronegative cows in 25 management groups. Results We found N. caninum in all herds, with an average of 20% of 2640 tested animals seropositive within management group; prevalence varied between 0% and 94%. At 7 of 10 sites assessed, there was evidence of horizontal transmission of N. caninum. There was no overall difference in pregnancy rate (79% vs 75%; P > 0.05), reproductive wastage after confirmed pregnancy diagnosis (11% vs 10%; P > 0.05) or weaning rate (67% vs 68%; P > 0.05) between seronegative and seropositive cows, respectively. In one herd where a combination of risk factors for N. caninum was present, a significant reduction in pregnancy rate occurred after the 6 months mating (85% vs 69%; P < 0.05). The fetal and calf losses observed were lowest in south-east Queensland (4.3% of 117 pregnancies), highest in north-west Queensland (15.5% of 413 pregnancies) and intermediate in north-east Queensland (10.2% of 1625 pregnancies). Other infectious agents that are known to cause reproductive wastage were endemic in many herds, though none appeared to cause significant fetal or calf loss in this study. Conclusion Despite a high prevalence of N. caninum, there was no apparent effect on beef cattle reproduction, but there is potential to cause reproductive wastage if known risk factors to neosporosis are in effect.

Genetics of early and lifetime annual reproductive performance in cows of two tropical beef genotypes in northern Australia

Reproduction records from 2137 cows first mated at 2 years of age and recorded through to 8.5 years of age were used to study the genetics of early and lifetime reproductive performance from two genotypes (1020 Brahman and 1117 Tropical Composite) in tropical Australian production systems. Regular ultrasound scanning of the reproductive tract, coupled with full recording of mating, calving and weaning histories, allowed a comprehensive evaluation of a range of reproductive traits. Results showed components traits of early reproductive performance had moderate to high heritabilities, especially in Brahmans. The heritability of lactation anoestrous interval in 3-year-old cows was 0.51 +/- 0.18 and 0.26 +/- 0.11 for Brahman and Tropical Composite, respectively. Heritabilities of binary reproductive output traits (conception rate, pregnancy rate, calving rate and weaning rate) from first and second matings were generally moderate to high on the underlying scale. Estimates ranged from 0.15 to 0.69 in Brahman and 0.15 to 0.34 in Tropical Composite, but were considerably lower when expressed on the observed scale, particularly for those traits with high mean levels. Heritabilities of lifetime reproduction traits were low, with estimates of 0.11 +/- 0.06 and 0.07 +/- 0.06 for lifetime annual weaning rate in Brahman and Tropical Composite, respectively. Significant differences in mean reproductive performance were observed between the two genotypes, especially for traits associated with anoestrus in first-lactation cows. Genetic correlations between early-in-life reproductive measures and lifetime reproduction traits were moderate to high. Genetic correlations between lactation anoestrous interval and lifetime annual weaning rate were -0.62 +/- 0.24 in Brahman and -0.87 +/- 0.32 in Tropical Composite. The results emphasise the substantial opportunity that exists to genetically improve weaning rates in tropical beef cattle breeds by focusing recording and selection on early-in-life female reproduction traits, particularly in Brahman for traits associated with lactation anoestrus.