Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “REPRODUCTION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1993

Assisted reproductive technology in the United States and Canada: 1991 results from the Society for Assisted Reproductive Technology generated from the American Fertility Society Registry.

OBJECTIVE: To summarize the procedures and outcomes of assisted reproductive technology (ART) initiated in the United States in 1991. DESIGN: Data were collected on an annual summary form and submitted to the Society for Assisted Reproductive Technology generated from The American Fertility Society central registry. PARTICIPANTS: Two hundred fifteen programs submitted data on procedures performed in 1991. Data were collected in October of 1992 so that outcome of all pregnancies established would be known. MAIN OUTCOME MEASURES: The outcomes measured included clinical pregnancy, ectopic pregnancy, abortion, stillbirth, delivery, and congenital abnormality. RESULTS: In 1991, programs reported initiation of 33,001 cycles of ART treatment, excluding frozen embryo and donor oocyte cycles. Of these, 24,671 cycles initiated were IVF with 15.2% deliveries per retrieval, 5,452 were cycles of GIFT with 26.6% deliveries per retrieval, and 2,104 were cycles of zygote intrafallopian transfer with 19.7% deliveries per retrieval, and 714 were combination cycles, combining IVF and one of the tubal transfer techniques, resulting in 19.3% deliveries per retrieval. In addition to these cycles initiated in 1991, 4,838 frozen embryo procedures were reported, either as separate procedures or in combination with another ART procedure with 11.1% deliveries per procedure, and 1,107 donor oocyte or surrogacy cycles were initiated with an overall success of 25.6% deliveries per retrieval. From all of these procedures, a total of 5,699 deliveries were reported. CONCLUSIONS: In 1991, there were more programs offering more treatment cycles of ART. Average success rates for most ART procedures exhibited a small increase compared with previously reported summaries.

Adult↗
PubMed2006

Monitoring reproductive health in Europe--what are the best indicators of reproductive health?

Setting up goals to monitor if the goals are achieved and to compare health performance over time and between regions is part of modern health care. A key part in this process is to choose the right indicators. The indicators in reproductive health should be selected on the basis of relevance and validity. They should be simple and action oriented because monitoring for the sake of monitoring alone may do more harm than good. We invite comments from the readers of Human Reproduction on a set of indicators suggested by Reprostat.

Europe↗
PubMed1997

The relationships among reproductive endpoints in Swiss mice, using the reproductive assessment by Continuous Breeding database.

The database of Continuous Breeding mouse studies was evaluated to determine the relationships between the functional indicators of reproduction (pup measures) and the various necropsy endpoints collected for males and females. Of 72 chemicals studied, both males and females were affected in 33 studies, while females and/or conceptuses were affected in 7. Two compounds affected only males, 17 studies were negative, and in 13 studies with effects it was not possible to clearly determine the affected gender(s). Greater F0 dam weight was correlated with increased pup mass per litter; this relationship was strongest for the first litter, and weakest for the fifth litter. For both generations of treated females (F0 and F1), longer estrous cycles correlated with reduced numbers of pups; the relationship was stronger in F0 than in F1 females and was not seen in controls. Sperm parameters had different distributions in treated mice than in control mice. Fertility (total live pups/number of pairs cohabited) was reduced if there were > approximately 15% sperm abnormalities or if sperm motility (moving/not moving) was < approximately 37%. Both of these relationships appeared to have thresholds. Epididymal sperm count in treated animals, however, was linearly related to fertility, even within the control range, suggesting strongly that other factors are important. Using both treated and control data together, combining sperm count with motility could explain much (r = 0.77) of the variation in fertility; adding morphology did not significantly improve the correlation. The model was almost as strong using count and morphology, in which case adding motility did not strengthen the model. This analysis of these studies shows that while some endpoints (e.g., random-estrous-cycle-point ovary weight) correlate poorly with fertility, other necropsy endpoints (epididymal sperm count and motility, estrous cycle length, and testis and epididymal weights) can be useful (though not complete) surrogates of overall reproductive function. Indeed, over many studies, epididymal sperm count in treated animals correlates with fertility so well that even small reductions (approximately 20%) in count result in reduced fertility, suggesting that mice may be better models of human fertility than was previously believed.

Animals↗
PubMed1999

Food and Drug Administration proposed testing guidelines for reproduction studies. Revision Committee. FDA Guidelines for Developmental Toxicity and Reproduction, Food and Drug Administration.

In the United States, the Food and Drug Administration (FDA) is the agency responsible for ensuring that the direct food additives and color additives used in food are safe for all consumers. In order to determine the safety of these additives for consumption, appropriate information and results from a series of tests must be made available to the agency. In 1982, in an effort to provide guidance to the food industry concerning the appropriate tests for the determination of safety, the FDA issued the Toxicological Principles for the Safety Assessment of Direct Food Additives and Color Additives Used in Foods, commonly referred to as the Redbook. In 1993, based on the expansion of technology and the use of food additives, as well as the refinement of the scientific criteria for establishing safety, the FDA updated its guidelines and issued the draft Redbook II. Since Redbook II was issued, additional refinements have been made in the procedures for the multigeneration reproduction study and for the assessment of effects on male reproduction. The latest proposed guidelines for multigeneration studies are provided here.

Animals↗
PubMed2004

Reproductive traits in the spur-thighed tortoise (Testudo graeca terrestris): new tools for the enhancement of reproductive success and survivorship.

The Mediterranean tortoise (Testudo graeca) is listed as "Vulnerable" on the IUCN Red List. Reproductive characteristics and means to increase offspring production were studied in T. graeca terrestris in a semi-natural environment. Courtship and mating occurred during early spring for about 4 weeks, followed by a laying season of approximately 2 months, with a second, shorter mating period in the fall. During the first mating, calcified eggs were already present in the uterus; we inferred that sperm from both mating seasons were stored in the oviduct for fertilization of eggs of the second laying cycle and of the following year. Average egg production was 3.8+/-0.3 eggs/year. Most females laid all of their eggs in a single clutch, but 18% laid in a second clutch, 11-21 days later. X-ray radiography revealed calcified eggs in the uterus about 4 weeks before oviposition. All eggs in the uterus were calcified simultaneously and were laid in a single clutch; if a second clutch developed, those eggs were also calcified simultaneously. Based on endoscopic examinations, ovaries were active throughout the entire year. Plasma progesterone concentrations in females were very low and were detected only soon after oviposition ( 440 +/-141 pg/ml). Plasma estradiol concentrations in females varied from 4.1 +/-1.5 pg/ml to 70.2 +/-29.4 pg/ml, with no clear seasonal pattern. Maintaining tortoises at a low environmental temperature (9 +/-1 degrees C versus 28 +/- 1 degrees C) reduced plasma estradiol concentrations. Giving 2mg/kg tamoxifen (TAM) increased plasma estradiol to 220 +/-33 pg/ml when treatment was given in September but not in late October, winter or spring. Treatment with TAM increased the number of eggs laid during the following laying season to 7.3 +/- 1.0 eggs/year, laid in one to three clutches. In males, plasma testosterone concentrations had a seasonal pattern with the onset of a rise in July from 2 to >4ng/ml, a continued increase to a peak of 12.8+/-5.3 ng/ml during November and a decline thereafter. Artificial incubation in sand at 29 +/-1 degrees C shortened the natural incubation time of 103+/-3.1 days to 83.5 +/- 1.3 days, increased hatching rate from 28 to 53%, and increased survival rate from 51 to 71% at 40 weeks of age. In summary, this study provides options for increasing reproductive performance, hatchability and offspring survival in captive Mediterranean tortoises, and may offer new tools for conservation of animals that are on the verge of extinction.

Animals↗
PubMedDate not supplied

Developmental and reproductive toxicity evaluation of toluene vapor in the rat. I. Reproductive toxicity.

The reproductive toxicity of toluene was evaluated in a 2-generation test in which male and female Sprague-Dawley rats, parental (F0) and first generation (F1), were exposed to toluene via whole body inhalation, 6 h/day, 7 days/week for 80 days premating and 15 days of mating at concentrations of 0, 100, 500 and 2000 ppm (0, 375, 1875 and 7500 mg/m(3)). Toluene was administered at 2000 ppm to both sexes, or to females or males only to be mated with untreated partners. Pregnant females at all dose levels were exposed from gestation day (GD) 1-20 and lactation day (LD) 5-21. At LD5, females were removed from their litters for daily exposure and returned when 6 h of exposure was completed. F1 pups selected to produce the F2 generation were treated for 80 days beginning immediately after weaning (LD21) and initially mated at a minimum of 100 days of age. F2 pups were not exposed to toluene by inhalation. Toluene exposure did not induce adverse effects on fertility, reproductive performance, or maternal/pup behaviors during the lactation period in males and females of the parental or first generation, but did inhibit growth in F1 and F2 offspring in the 2000 ppm (both sexes treated) and 2000 ppm (females only treated) groups. Caesarean section of selected 2000 ppm (both sexes treated) dams at GD20 showed reduced fetal body weight and skeletal variations. Exposure to toluene caused decreased pup weights throughout lactation in F1 and F2 2000 ppm (both sexes treated), and 2000 ppm (females only treated) groups. Exposure at 2000 ppm to male parents only did not induce similar weight inhibition in offspring. The toluene offspring NOAEL is 500 ppm in groups in which maternal animals were exposed, and 2000 ppm for male only treated groups.

Abnormalities, Drug-Induced↗
PubMed2003

A comment on the European Society of Human Reproduction and Embryology/American Society for Reproductive Medicine consensus of the polycystic ovarian syndrome.

This commentary on the European Society of Human Reproduction and Embryology/American Society for Reproductive Medicine (ESHRE/ASRM) consensus on diagnosis, nomenclature and long-term health risks of the polycystic ovarian syndrome (PCOS) (conference in Rotterdam, Netherlands, March 2003) questions whether the preservation of the term PCOS sufficiently considers the modern aspects of the aetiology and pathogenesis of this complex syndrome. The misleading and simplified term PCOS, which comprises a variety of different entities, carries with it the risk of misinterpretation and under- and overestimation of symptoms, as well as of overlooking contraindications. Additionally, bias in future studies is pre-programmed. In this commentary, it is proposed that the term polycystic should be substituted with polyfollicular, and the term PCOS with functional hyperandrogenism, which is further subdivided into five additional groups. By using this new classification, most of the patients' dysfunctions belonging to the unspecifically termed PCOS are clearly defined, which leads on to the assumption that the diagnostic and therapeutic approaches required will improve, and the amount of bias in both basic and clinical studies will be reduced, respectively.

Embryo, Mammalian↗
PubMed2006

Obesity is associated with altered metabolic and reproductive activity in the mare: effects of metformin on insulin sensitivity and reproductive cyclicity.

In mares, obesity is associated with continuous reproductive activity during the non-breeding season. To investigate the effect of obesity and associated alterations in metabolic parameters on the oestrous cycle, two related studies were conducted. In Experiment 1, obese (body condition score > 7) mares were fed ad libitum or were moderately feed restricted during the late summer and autumn months. Feed restriction did not alter the proportion of mares entering seasonal anoestrus. However, obese mares exhibited a significantly longer duration of the oestrous cycle, significant increases in circulating concentrations of leptin and insulin, and decreased insulin sensitivity and concentrations of thyroxine compared with feed-restricted mares throughout the experiment. Experiment 2 was designed to investigate the effects of administration of the insulin-sensitising drug metformin hydrochloride on insulin sensitivity and the characteristics of the oestrous cycle in obese mares. In a dose-response trial, metformin increased insulin sensitivity after 30 days following administration of 3 g day(-1), but not 6 or 9 g day(-1), compared with controls receiving vehicle only. However, there were no differences in insulin sensitivity or oestrous cycle characteristics between control and metformin-treated groups when the 3 g day(-1) dose was tested for a longer period of 2 months. These results demonstrate that obesity is associated with aberrations in the oestrous cycle and perturbations in several markers of metabolic status. The results also indicate that metformin is not an effective long-term monotherapy for increasing insulin sensitivity in horses at the doses tested. Additional studies are needed to examine possible effects of increasing insulin sensitivity on reproductive activity in obese mares.

Animals↗
PubMed2004

Reproductive ecology of the endangered Alpine species Eryngium alpinum L. (Apiaceae): phenology, gene dispersal and reproductive success.

BACKGROUND AND AIMS: Eryngium alpinum (Apiaceae) is an endangered perennial, characteristic of the Alpine flora. Because the breeding system influences both demographic (reproductive success) and genetic (inbreeding depression, evolutionary potential) parameters that are crucial for population maintenance, the reproductive ecology of E. alpinum was investigated. Specifically, the aims of the study were (1) to determine the factors (resources and/or pollen) limiting plant fitness; and (2) to assess the potential for gene flow within a plant, within a patch of plants, and across a whole valley where the species is abundant. METHODS: Field experiments were performed at two sites in the Fournel valley, France, over three consecutive years. Studies included a phenological survey, observations of pollinators (visitation rates and flight distances), dispersal of a fluorescent powder used as a pollen analogue, the use of seed traps, determination of the pollen/ovule ratio, and an experiment to test whether seed production is limited by pollen and/or by resources. KEY RESULTS: E. alpinum is pollinated by generalist pollinators, visitation rates are very high and seed set is resource- rather than pollen-limited. The short flights of honeybees indicate a high potential for geitonogamy, and low pollen and seed dispersals suggest strong genetic structure over short distances. These results are interpreted in the light of previous molecular markers studies, which, in contrast, showed complete outcrossing and high genetic homogeneity. CONCLUSION: S. The study highlights the usefulness of adopting several complementary approaches to understanding the dynamic processes at work in natural populations, and the conservation implications for E. alpinum are emphasized. Although the studied populations do not seem threatened in the near future, long-term monitoring appears necessary to assess the impact of habitat fragmentation. Moreover, this study provides useful baseline data for future investigations in smaller and more isolated populations.

Ecology↗
PubMed2002

Alternative treatments in reproductive medicine: much ado about nothing. Acupuncture-a method of treatment in reproductive medicine: lack of evidence of an effect does not equal evidence of the lack of an effect.

The increasing popularity of alternative treatments-methods of treatment that are not generally established in Western medicine-demands a serious debate about scientific documentation, efficacy and safety. It has been argued that there is no alternative medicine. There is only scientifically proven, evidence-based medicine supported by solid data, and we agree. Different methods of treatment, referred to as alternative treatments, are used by millions of patients every day which generates billions of dollars in health care expenditure each year. Therefore, it is important that physicians become more knowledgeable about different methods of treatment and increase their understanding of the possible benefits and limitations of each therapy. This article is intended to illustrate acupuncture in reproductive medicine today, as an example of a method of treatment that has become more established in Western medicine over the last decade. Discussed are the scientific documentation and aspects of acupuncture research, the physiological basis for the use of acupuncture, and evidence for the use of acupuncture in reproductive medicine. We are well aware that there are few well-designed papers on the effectiveness of different treatments in this field. However, we need to adhere to these principles, as we hope, do the readers of the present debate article.

Acupuncture↗
PubMed2004

What is the most relevant standard of success in assisted reproduction?: no single outcome measure is satisfactory when evaluating success in assisted reproduction; both twin births and singleton births should be counted as successes.

The 2002 recommendation of the consensus meeting of the European Society of Human Reproduction and Embryology (ESHRE) that the outcome measure of assisted reproductive technology (ART) and non-ART should be 'singleton live birth rate' could profoundly effect the ability of infertility patients to become pregnant. We reviewed published reports and new data concerning elective single embryo transfer (eSET) vs. double embryo transfer (DET) and the outcome of twin pregnancies in the United States, as well as recommendations of other Societies concerning number of embryos to transfer and methods used to measure ART success. We found that no single outcome measure of ART is ideal. Mandatory eSET would result in 42%-70% fewer births compared to DET. Infertility treatments account for only 12% of all twin pregnancies and 4% of all premature births in the United States. Twin and singleton births due to ART do not occur earlier than spontaneously conceived twins and singletons unless they started as triplet and higher order pregnancies. Multiple outcome measures are necessary when evaluating ART success. Twin as well as singleton births should be counted as ART successes. The essential aim of infertility treatment should be a healthy low order (singleton or twin) birth.

Embryo Transfer↗
PubMed1982

The thymus gland and reproduction: do thymic peptides influence the reproductive lifespan in females?

Thymic hormones may play an important role in determining the reproductive lifespan in females. Thymic peptides can release gonadotropin-releasing hormone (GnRH) from the hypothalamus and thus luteinizing hormone (LH) from the pituitary gland in vitro. Independent data are also accumulating to show that gonadotropins may be necessary to prevent atresia of primordial follicles in utero. It is possible that thymic peptides regulate the release of GnRH-LH in utero in women and are important in determining the rate at which primordial follicles and oogonia are lost. Thus, thymic peptides may play a role in fixing the number of oocytes available for ovulation during the reproductive lifespan.

Adolescent↗
PubMed1997

Aspergillus asexual reproduction and sexual reproduction are differentially affected by transcriptional and translational mechanisms regulating stunted gene expression.

The Stunted protein (StuAp) is a member of a family of transcription factors that regulate fungal development and cell cycle progression. Regulated stuA gene expression is required for correct cell pattern formation during asexual reproduction (conidiation) and for initiation of the sexual reproductive cycle in Aspergillus nidulans. Transcriptional initiation from two different promoters yields overlapping mRNAs (stuA alpha and stuAbeta) that upon translation yield the same protein. Here we show that multiple regulatory mechanisms interact to control (i) developmental competence-dependent expression of both transcripts and (ii) induction-dependent expression of stuA alpha, but not stuAbeta, by the conidiation-specific Bristle (BrlAp) transcriptional activator. Quantitative levels of both mRNAs are further modulated by (i) an activator(s) located at a far-upstream upstream activation sequence, (ii) feedback regulation by StuAp, and (iii) positive translational regulation that requires the peptide product of a micro-open reading frame unique to the stuA alpha mRNA 5' untranslated region. Gradients in stuA alpha expression were most important for correct cell and tissue type development. Threshold requirements were as follows: metula-phialide differentiation < ascosporogenesis < cleistothecial shell-Hülle cell differentiation. Altered stuA expression affected conidiophore morphology and conidial yields quantitatively but did not alter the temporal development of cell types or conidiophore density. By contrast, the sexual cycle showed both temporal delay and quantitative reduction in the number of cleistothecial initials but normal morphogenesis of tissue types.

Amino Acid Sequence↗
PubMed1990

Adding the heterochromatic YL arm to an X chromosome reduces reproductive fitnesses in Drosophila melanogaster: implications for the evolution of rDNA, heterochromatin, and reproductive isolation.

For X-Y exchange to be of importance in the coevolution of X and Y rDNA, there must be a mechanism to maintain cytologically normal X chromosomes in the face of continual infusions of X.YL chromosomes produced by X-Y exchanges. Replicated populations were founded with different frequencies of isogenic X and X.YL chromosomes. The X.YL chromosome declined in frequency over time in all lines. Relative fitnesses, estimated from chromosome frequency trajectories, were 0.40, 1.01, and 1.0 for X.YL/X.YL, X.YL/X, and X/X females and 0.75 and 1.0 for X.YL/Y and X/Y males, respectively. The equilibrium frequency for the X.YL chromosome due to the balance between X-Y exchange and selection was predicted to be 4-16 x 10(-4). The results strengthen the evidence for the involvement of X-Y exchange in the coevolution of X and Y rDNA arrays. Conditions for the evolution of reproductive isolation by sex-chromosome translocation are much less probable than previously supposed since the X.YL translocation chromosome is at a selective disadvantage to cytologically normal X chromosomes. Additional heterochromatin was not neutral but was only deleterious beyond a threshold, as one dose of the heterochromatic XL arm did not reduce female reproductive fitness, but two doses did.

Animals↗
PubMed1994

Isolation and serological characterization of porcine reproductive and respiratory syndrome (PRRS) viruses from pigs with reproductive and respiratory disorders in Japan.

Three porcine reproductive and respiratory syndrome viruses (PRRSVs) were successfully isolated from stillborn piglets and fattening pigs derived from different herds affected either with an epizootic reproductive failure or a severe chronic respiratory distress in Japan. The isolates were reacted with antisera against both European (Lelystad virus) and American (strain 46448) PRRSVs in indirect immunofluorescence (IIF). However, cross immunoperoxidase monolayer assay revealed the close serological relationships between the Japanese isolates and American PRRSV, but not between the Japanese isolates and the European PRRSV. The data of preliminary serological survey with IIF technique showed a high frequency of antibody positive pigs against both Japanese isolate and the American PRRSV, whereas a low frequency of antibody positive pigs against the European PRRSV, on herds which have had clinical episodes of PRRS-like diseases. These results indicate that PRRSVs are prevalent in Japan, and suggest that the antigenicities of the prevalent PRRSVs are more closely related to those of the American than the European PRRSVs.

Animals↗
PubMed2004

Disruption of reproductive activity of Coptotermes formosanus (Isoptera: Rhinotermitidae) primary reproductives by three chitin synthesis inhibitors.

Effects of the chitin synthesis inhibitors (CSIs) diflubenzuron, hexaflumuron, and lufenuron on the Formosan subterranean termite, Coptotermes formosanus Shiraki, primary reproductives were studied in the laboratory. Incipient colonies were established by collecting and pairing C. formosanus alates and placing them in dishes containing an artificial diet. Three groups of 56 colonies each were fed with a diet containing 10 ppm of one of each of the CSIs and were compared with a control group fed with an untreated diet. All eggs oviposited by treated young queens failed to hatch at the end of 6 mo. Estimated queen fecundity was significantly lower in the lufenuron treatment compared with the control group. Fecundity of hexaflumuron-treated queens did not differ significantly from that of queens from the control group and the other treatments. Adult mortality was significantly higher in the diflubenzuron and lufenuron treatments than in the control group at the end of 6 mo., but not in the hexaflumuron treatment. All the pairs died within 8 mo. in the diflubenzuron and lufenuron treatments, even after treatment was suspended at the end of 6 mo. Mortality in the hexaflumuron treatment was significantly higher than in the control group by the end of 9 mo. The three CSIs tested eliminated reproduction in C. formosanus by preventing egg hatching and induced adult mortality. Possible mechanisms by which CSIs induce termite adult death are discussed.

Animals↗
PubMed1979

Reproduction study of carteolol hydrochloride in mice. Part I. Fertility and reproductive performance.

Carteolol was administered orally by gastric intubation at 3, 15, 75 or 150 mg/kg/day to ICR-JCL mice of both sexes prior to mating and to females during early stage of pregnancy to determine its effects on the entire reproductive process and fetal development. Following results were obtained: 1) The decrease of spontaneous motor activity was observed in all treatment groups, and some animals in the 75 mg/kg and 150 mg/kg groups pressed the chest or abdomen against the cage wall. 2) The incidence of early resorptions in the 75 mg/kg and 150 mg/kg groups was significantly higher than that in controls.3) The ossification of the talus and calcaneus was significantly retarded in the 75 mg/kg and 150 mg/kg groups. The maximum non-effective dose on fertility and reproduction for carteolol was estimated to be 15 mg/kg/day, although the incidence of early resorptions was slightly elevated with this dose.

Animals↗
PubMed1983

Genotype x environmental interactions on reproductive traits of bovine females. III. Seasonal variation in postpartum reproduction as influenced by genotype, suckling and dietary regimen.

We examined the effect of season of calving (winter = October to March, summer = April to September) on postpartum reproductive traits by analyzing six data sets in which cows calved throughout the year. In two experiments, with suckled and nonsuckled cows, animals that calved in winter had longer (P less than .01) intervals from parturition to first estrus (IE) than those that calved in summer. Multiple regression analysis [model; IE = y + b1 (calving date) + b2 (calving date)2] indicated that the relationship between calving date and IE was less for nonsuckled cows than for suckled cows because there was heterogeneity of regression (P less than .005) between groups. A similar seasonal difference and calving date X suckling status interaction (P less than .10) was observed in a third experiment. Another experiment involved Holstein cows ranked for genetic ability for milk production. Cows with genetic ability for high milk production and calving in summer tended (P less than .12) to have shorter IE than winter-calving cows. Genetically low producing cows did not show this tendency and there was heterogeneity of regression (P less than .10) between groups. In two experiments cows were fed diets either low or high in energy and data were analyzed for three consecutive postpartum periods (PP1, PP2, PP3) beginning after first calving. In PP1 of one experiment, intervals to first ovulation, estrus and conception were longer in winter than in summer. The multiple regression equation between calving date and IE was significant (P less than .10) only for cows fed diets low in energy. There was no significant relationship between calving date and IE in PP2 or PP3. In the other experiment, there were not enough winter-calving cows to make seasonal comparisons in PP1 and season did not significantly influence IE in PP2 or PP3. We concluded that, in general, winter-calving cows appeared to take longer to regain reproductive competence after calving than summer-calving cows. Differences between seasons tended to be greater for suckled cows, cows with genetic ability for high milk production, primiparous cows and cows fed diets low in energy.

Animal Population Groups↗