Ovum Maturation Research Articles

Heartache to Happiness: Managing a Six Year Hormonal Subfertility with a Successful Rate of Conception

Background: The inability to conceive is emotionally distressing and indeed a very painful struggle in which the pain stays with the individual every day. Hormonal disorders are the leading cause of infertility globally. They do not only include the hypothalamic pituitary ovarian axis but also the none-reproductive endocrine glands. Hormonal management helps promote ovum maturation, which triggers ovulation, increasing the likelihood of conception. Case presentation: We report a 36-year-old African lady who presented with an inability to conceive for six years since marriage and it was associated with an irregular menstruation cycle length of twenty-four to thirty-six days. She had anovulatory cycles for seven years, and high Prolactin levels. Her body mass index was 34.4kg/m2. She had visited several hospitals in and outside Tanzania without success in conceiving. At Bugando Medical Centre we managed her case by diet, fertility awareness, and medical management. She conceived after three months of treatment. Conclusion: Anovulatory cycles with abnormal bleeding patterns are a major cause of infertility in reproductive woman. Basic hormonal profiles are essential to confirm where the problem is. Prolactinemia and insulin resistance affects ovulation. Fertility awareness, lifestyle changes, and medical management will bring back happiness to most women with subfertility secondary to hormonal disorders.

Prevalence of Human Papillomavirus Infection in the Female Partner of Infertile Couples Undergoing IVF/ICSI-ET and Subsequent Reproductive Outcomes.

We investigated the prevalence of human papillomavirus (HPV) infection in the female partner of infertile couples and the reproductive outcomes after in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET). We conducted a retrospective analysis on 8117 women from infertile couples who underwent IVF/ICSI treatment and evaluated the prevalence of HPV infection in these women. The prevalence of HPV infection in the female partner of infertile couples was 9.2% (747/8117). These HPV-infected female patients undergoing ART were divided into high-risk HPV (hrHPV) (n = 130) and low-risk HPV (lrHPV) groups (n = 94), and non-infected women patients formed the negative group (n = 126). Of the 747 cases infected with HPV, 529 showed hrHPV infection (70.82%; primarily genotypes 16, 52, 53, 58, and 59); 175 exhibited lrHPV infection (23.43%; primarily genotypes 6, 43, 44, 55, 61, and 81); and 43 cases were co-infected with hrHPV and lrHPV (5.76%). Except for the Day-3 high-quality embryo rate, there were no differences in ovum maturation, fertilization, implantation, clinical pregnancy, live birth, or miscarriage rates between women infected with HPV and non-infected women (p > 0.05); however, we noted an increased miscarriage rate after logistic regression analyses (OR, 0.16; 95% CI, 0.03−0.84; p = 0.041). For single-male-factor-induced infertility in couples (smHPV), although we likewise observed no differences in ovum maturation, fertilization, or implantation rates (p > 0.05) between the smHPV group and the negative group, we discerned diminutions in the Day-3 high-quality embryo rate (46.01% vs. 70.04%, p = 0.013), clinical pregnancy rate (46.67% vs. 57.94%, p = 0.003), and live birth rate (33.33% vs. 46.83%, p = 0.027) as well as an augmented miscarriage rate (11.11% vs. 4.76%, p = 0.003), respectively. Logistic regression analyses indicated that smHPV was a risk factor for decreased clinical pregnancy rate (OR, 4.17; 95% CI, 2.31−7.53; p < 0.001) and live birth rate (OR, 1.83; 95% CI, 0.81−2.14; p = 0.045) and elevated miscarriage rate (OR, 6.83; 95% CI, 2.22−21.00; p = 0.001). HPV infection in women was associated with increased miscarriage rate, and single-male-factor infertility influenced reproductive outcomes in couples undergoing IVF/ICSI treatment. Both were potentially due to HPV infection in the couple.

MANAJEMEN ASUHAN KEBIDANAN KESEHATAN REPRODUKSI PADA NY “N” DENGAN ANEMIA PADA WANITA PRAKONSEPSI DI RSUD LABUANG BAJI MAKASSAR

Introduction Preconception is the period before pregnancy or prior to the meeting of the ovum with sperm. Adequate nutrition intake during the preconception will support the functional reproductive system as it smoothens the process of ovum maturation, ovum production, and ovum quality and complete fertilization process. Anemic preconception puts women at a higher risk of anemia in pregnancy, which eventually impacts on the fertilization process and fetal development. This study aimed to conduct the management of reproductive health midwifery care on Mrs. “N” with preconception anemia in Regional Public Hospital of Labuang Baji Makassar. Method This research in accordance with the 7-step Varney. Result The findings suggest that Mrs. “N” reported several complaints including fatigue, frequent dizziness, pale conjunctiva appearance, dry lip mucosa, and Hb 11.9 g/dl as shown from the laboratory results. The midwifery care was conducted by providing the patient with iron tablets containing 60 mg of elemental iron and 250 folic acids. In addition to that, the medical team also gave a recommendation that the patient consume date juice as well as 7 pieces of dates every morning. Conclusion This study concluded the midwifery care using the 7-step Varney and SOAP for Mrs. “N” with preconception anemia in Regional Public Hospital of Labuang Baji Makassar with results of increasing Hb levels up to 15.8 gr/dl, composmentis awareness, normal vital signs, and no abnormalities nor complications shown from the physical examination. These results show that there is no gap between all the treatments and the theories.

The reproductive biology of small fishes and the clutch concept: Combining macroscopic and histological approaches

AbstractAccurate estimates of reproductive parameters important in understanding life history evolution and conservation of small fishes are dependent upon careful assignment of ovarian phases. Proper assignment is based upon the stages of propagule (oocyte) development, oocyte maturation and the location of any clutch or portion thereof within the ovaries. Macroscopic inspection and assignment of ovarian developmental phases have often been used for small freshwater fishes. By contrast, histological methods for assignment of reproductive phases have been developed and are widely used for marine fishes, but they have rarely been used for small freshwater fishes. We review oocyte development, ovum maturation, and the ovarian cycling process using both macroscopic and histological approaches which incorporate the clutch concept. New terminology, including three actively spawning phases based on macroscopic appearance of the clutch (actively spawning‐maturation, actively spawning‐hydration, actively spawning‐ovulation), is proposed. We assert that combining histological and macroscopic methodologies, shown to be complementary, will allow a more accurate and precise understanding of the reproductive biology of small fishes—especially freshwater fishes experiencing effects of habitat change and loss of habitat.

Pre-Mature Raise of Progesterone and its Effect on Clinical Pregnancy Rate and Live Birth Rate in Intra-Cytoplasmic Sperm Injection (ICSI) Cycles

Background: During controlled ovarian hyper-stimulation COH, level of Progesterone on a day of human chorionic gonadotrophin (hCG) trigger for a final ovum maturation has a precious role for implantation of the embryos. Aims: This study aims to investigate the incidence and the effect of Premature Progesteron Rise (PPR) on pregnancy rates PR as well as live birth rate LBR in ICSI cycle. Material and Methods: A total of 710 patients undergoing ICSI cycles with fresh embryo transfer at Misurata National Infertility Centre were retrospectively involved. Patients included in the study who are <40 years with good ovarian response and had long agonist/antagonist ICSI protocols with fresh embryo transfer. Results: The average age of patients was (32.26 years ± 4.924). The cut-off value found in this study to define PPR is (1.064 ng/ml). The overall incidence of serum PPR on hCG administration was 31.32%. The average serum PPR on a day of hCG administration was (1.1 ±1.8) ng/ml. PPR had a negative significant effect on PR (P-value 0.03). Conclusion: In order to improve ICSI outcome, the PR is significantly negatively correlated with PPR. So, when serum P4 level is approaching the cutoff value (1.064 ng/ml) during COH, modification of the clinical treatment might be considered to improve the ICSI outcomes.

Pre-Mature Raise of Progesterone and its Effect on Clinical Pregnancy Rate and Live Birth Rate in Intra-Cytoplasmic Sperm Injection (ICSI) Cycles

Background: During controlled ovarian hyper-stimulation COH, level of Progesterone on a day of human chorionic gonadotrophin (hCG) trigger for a final ovum maturation has a precious role for implantation of the embryos. Aims: This study aims to investigate the incidence and the effect of Premature Progesteron Rise (PPR) on pregnancy rates PR as well as live birth rate LBR in ICSI cycle. Material and Methods: A total of 710 patients undergoing ICSI cycles with fresh embryo transfer at Misurata National Infertility Centre were retrospectively involved. Patients included in the study who are <40 years with good ovarian response and had long agonist/antagonist ICSI protocols with fresh embryo transfer. Results: The average age of patients was (32.26 years ± 4.924). The cut-off value found in this study to define PPR is (1.064 ng/ml). The overall incidence of serum PPR on hCG administration was 31.32%. The average serum PPR on a day of hCG administration was (1.1 ±1.8) ng/ml. PPR had a negative significant effect on PR (P-value 0.03). Conclusion: In order to improve ICSI outcome, the PR is significantly negatively correlated with PPR. So, when serum P4 level is approaching the cutoff value (1.064 ng/ml) during COH, modification of the clinical treatment might be considered to improve the ICSI outcomes.

Analysis of expression of genes responsible for regulation of cellular proliferation and migration – microarray approach based on porcine oocyte model

Abstract The formation of mammalian oocytes begins in the ovary during fetal development. The proper development of oocytes requires close communication with surrounding somatic cells, the substances they emit allow proper maturation of oocytes. Somatic cumulus (CC) cells and oocytes form cumulus-oocyte (COC) complexes. In this study, the Affymetrix microarray analysis was used to investigate changes in gene expression occurring in oocytes before and after in vitro maturation (IVM). The aim of the study was to examine oocyte genes involved in two ontological groups, “regulation of cell migration” and “regulation of cell proliferation” discovered by the microarray method. We found a reduced expression of all 28 genes tested in the ontological groups: ID2, VEGFA, BTG2, CCND2, EDNRA, TGFBR3, GJA, LAMA2, RTN4, CDK6, IHH, MAGED1, INSR, CD9, PTGES, TXNIP, ITGB1, SMAD4, MAP3K1, NOTCH2 , IGFBP7, KLF10, KIT, TPM1, PLD1, BTG3, CD47 and MITF. We chose the most regulated genes down the IVM culture, and pointed out those belonging to two ontological groups. Increased expression of the described genes before IVM maturation may indicate the important role of these genes in the process of ovum maturation. After the maturation process, the proteins produced by them did not play such an important role. In summary, the study provides us with many genes that can serve as molecular markers of oocyte processes associated with in vitro maturation. This knowledge can be used for detailed studies on the regulation of oocyte maturation processes. Running title: Genes regulating cellular migration and proliferation in porcine oocytes

Environmentally Relevant Concentrations of Carbamazepine Caused Endocrine-Disrupting Effects on Nontarget Organisms, Chinese Rare Minnows (Gobiocypris rarus).

In the present study, Chinese rare minnows (Gobiocypris rarus) were exposed to 1, 10, and 100 μg/L of carbamazepine (CBZ) under flow-through conditions for 28 d. A hepatic-specific custom microarray identified 111 and 71 differentially expressed genes in the livers of females and males, respectively, exposed to 100 μg/L of CBZ (ratio ≥ 2, p ≤ 0.05). The levels of five differentially expressed genes associated with the hypothalamic-pituitary-gonadal (HPG) axis were quantified by qPCR, and the results indicated the feasibility of screening endocrine-disrupting chemicals using a custom microarray. The mRNA levels of genes related to the HPG axis differed significantly in different organs of Chinese rare minnows (p < 0.05). Significant differences were observed in the 11-ketotestosterone and plasma vitellogenin levels in all treatments and in the 17β-estradiol (E2) levels in the 100 μg/L CBZ treatment. In contrast, the gonadosomatic index was significantly higher in females and slightly higher in males without significant differences. A pathological analysis determined that 10 and 100 μg/L of CBZ could lead to ova-testis in males and significantly promoted ovum maturation in females. Therefore, our results demonstrate that environmentally relevant concentrations of CBZ have homologous estrogenic activity and induce reproductive toxicity in Chinese rare minnows.

A human genotyping trial to estimate the post-feeding time from mosquito blood meals.

Mosquitoes occur almost worldwide, and females of some species feed on blood from humans and other animals to support ovum maturation. In warm and hot seasons, such as the summer in Japan, fed mosquitoes are often observed at crime scenes. The current study attempted to estimate the time that elapsed since feeding from the degree of human DNA digestion in mosquito blood meals and also to identify the individual human sources of the DNA using genotyping in two species of mosquito: Culex pipiens pallens and Aedes albopictus. After stereomicroscopic observation, the extracted DNA samples were quantified using a human DNA quantification and quality control kit and were genotyped for 15 short tandem repeats using a commercial multiplexing kit. It took about 3 days for the complete digestion of a blood meal, and genotyping was possible until 2 days post-feeding. The relative peak heights of the 15 STRs and DNA concentrations were useful for estimating the post-feeding time to approximately half a day between 0 and 2 days. Furthermore, the quantitative ratios derived from STR peak heights and the quality control kit (Q129/Q41, Q305/Q41, and Q305/Q129) were reasonably effective for estimating the approximate post-feeding time after 2–3 days. We suggest that this study may be very useful for estimating the time since a mosquito fed from blood meal DNA, although further refinements are necessary to estimate the times more accurately.

Potential clinical application of Kisspeptin in reproductive endocrinology

Gonadotropin-releasing hormone (GnRH) plays an important role in the process of reproduction. Studies have shown that a family of peptides Kisspeptin can act on GnRH-related neurons, stimulating the secretion of GnRH, and activating the hypothalamic-pituitary-gonadal axis. Both animal experiments and clinical studies have shown that exogenous administration of Kisspeptin is able to induce physiological GnRH release in healthy individuals and those with endocrine-disorders, which brings great hope for treatment of reproductive endocrine diseases. The effect of Kisspeptin is similar to the physiological process in induction of ovulation and ovum maturation, leading to high security and efficiency for women receiving in vitro fertilization. Kisspeptin is involved in trophoblast invasion, so it may be useful for predicting pregnancy outcomes. In addition, Kisspeptin is the key hormone in the onset of puberty acting as a signal transducer in metabolism and reproduction, so it provides some directions for studies of polycystic ovary syndrome, hyperprolactinemia, and other metabolic-related reproductive endocrine diseases. This article reviews the character of Kisspeptin and the prospect of its application in treatment of reproductive endocrine diseases.

HCG Triggering in ART: An Evolutionary Concept.

Human chorionic gonadotropin (hCG) is no longer a single, omnipotent ovulation triggering option. Gonadotropin releasing hormone (GnRH) agonist, initially presented as a substitute for hCG, has led to a new era of administering GnRH agonist followed by hCG triggering. According to this new concept, GnRH agonist enables successful ovum maturation, while hCG supports the luteal phase and pregnancy until placental shift.

A Study of the Correlation of Some Sex Hormone with Obesity in Women with Secondary Infertility

Infertility is the inability to conceive a child for more than one year. The present study indicates that the obesity associated with infertility. The aim of the study to determine follicle stimulating hormone, luteinizing hormone, testosterone hormone and prolactin levels. and cholesterol and triglyceride concentration in 2nd inferetid women. This study was carried out at kamal al-samaarai hospital the data were collected from 95 secondary infertilial women were age between 16-45 years old and grouped them in to obese (n = 46) and non obese(n = 49). There was no significant difference between the two groups (p 0.05).The BMI was correlated positively with triglyceride in obese group while BMI was positive correlation highly significant with cholesterol in non obese group. Regression analysis revealed obese to be strongly associated with observed infertility. The elevated prolactin values in secondary infertile women clearly shows that there is a mechanism operating at the anterior pituitary level which shows an abnormal distribution of FSH and LH which may further explain the abnormal delay ovum maturation. This study also indicates obese associated with infertile more than non obese women.

Human gonadotropin-releasing hormone receptor-activated cellular functions and signaling pathways in extra-pituitary tissues and cancer cells (Review)

Human gonadotropin-releasing hormone receptor (GnRHR) and its natural ligand human gonadotropin-releasing hormone (GnRH) were initially described as signaling complexes that play a key role in reproductive functions. By binding to specific receptors present on pituitary gonadotropes, GnRH regulates the sperm and ovum maturation, as well as steroidogenesis within the context of the hypothalamus-hypophysis axis. The expression of GnRH and its receptor has clearly been established in many extra-pituitary organs. Some of them are tumors from non-reproductive tissues such as liver, larynx, pancreas, colon, lymphoma, kidney, skin, blood and brain as well as tissues from reproductive track, for example ovary, endometrium, prostate and breast or tumors derived from these organs. Expression of GnRH and its receptor in these organs has gained much attention and several research groups have established their role during cell proliferation and cell motility. Although the signaling pathways and their effector proteins in these samples remain unclear, the molecular mechanism employed for GnRH and its receptor in extra-pituitary tissues could be related with non-classical GnRHR-signaling pathways. In the present review, we explore the vast literature reported on GnRH and GnRHR principally in tumors, describing how cross-talk between GnRHR and growth factor receptor, the coupling between GnRHR and many G proteins depending on cell context, and the regulation of several proteins associated with cell proliferation and cell motility are employed by GnRHR/GnRH to regulate their extra-pituitary activities.

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Endometriosis and Infertility: A Multi‐cytokine Imbalance Versus Ovulation, Fertilization and Early Embryo Development

Endometriosis is tightly linked to infertility which is manifested at very early or more advanced stages of the gestational cycle. Alteration on the production of a great number of cytokines/growth factors can be accused for problems on ovum maturation, fertilization or implantation. Yet, macroscopically these stages are characterized by the inability of conception. A closer look of the cytokinic profile during the conceptional and early gestational cycle could, however, localize the problem and allow a therapeutic approach. In this commentary, going through the cytokine requirement during ovulation, fertilization and the early stages of pregnancy, it became possible to specifically define the harmful endometriosis-induced cytokines for each of the conceptional and early gestational stages. Thus, regulating the levels of interferon-γ and tumor necrosis-α will facilitate ovulation and fertilization, whereas adjusting the levels of interleukin-1β and colony stimulating gactor-1 will facilitate implantation.

Reproductive Timing of Fishes in a Tropical Intermittent Stream

Six fish species were studied in an intermittent lowland stream in Trinidad, West Indies for 28 months from 1980 to 1982. They were Gasteropelecus sternicla, Corynopoma riisei, Astyanax bimaculatus, Hemigrammus unilineatus, Corydoras aeneus and Poecilia reticulata. Peaks in GSIs and presence of mature adults and juveniles, as determined from monthly field collections, indicated reproduction coincident with the rainy seasons in all species except Poecilia. Gasteropelecus bred for a short period at the beginning of the main rainy season while Corynopoma, Corydoras and Hemigrammus had extended periods of breeding activity each year coincident with high rainfall. The presence of juveniles suggests that Astyanax also bred during the rainy season. Poecilia reproduced continuously throughout the study period but exhibited discharge-related adult stock fluctuations that may have influenced reproductive activity. Maximum ovarian fecundity correlated with species size suggested body size limitation on fecundity for small species such as Corynopoma and Hemigrammus. Size frequency distributions of oocytes in mature ovaries indicate synchronised ovum maturation in Astyanax and possibly Gasteropelecus, while Hemigrammus, Corynopoma and Corydoras showed evidence of continuous maturation of oocytes and multiple spawning. Prolonged small brood spawning was confirmed in the laboratory for Corynopoma and Hemigrammus and resulted in spawning fecundities up to 11 times greater than ovarian fecundities for Corynopoma. It is concluded that the conditions of intermittency in this stream did not significantly alter the reproductive styles of these species as described for other Neotropical environments, perhaps because of their opportunistic nature. Patterns of spawning for the characoids can be directly related to size and phylogeny.

Control of follicular steroidogenesis in early- and late-luteal phase goat ovaries

Follicles are the site of many important and complex phenomena during preovulatory and ovulatory periods, which lead to the processes of luteinization, steriodogenesis, ovum maturation and ovulation. To understand the steriodogenesis within the follicles during early- and late-luteal phase ovaries, experiments were conducted in goat ovarian follicles of >3 mm in size. Estradiol–17β (E 2), progesterone (P 4), testosterone (T), follicle stimulating hormone (FSH), luteinizing hormone (LH) and prolactin (PRL) activity were localized in early- and late-luteal phase ovaries using immuno-histochemical techniques. The enzymes involved in steroid synthesis i.e. glucose–6–phosphate dehydrogenase (G–6PD), –3β hydroxy steroid dehydrogenase (–3βHSD) and –17β hydroxysteroid dehydrogenase (–17βHSD) were localized histochemically. Results revealed that during the early luteal phase, follicular theca and granulosa cells showed almost no FSH, LH and PRL activity but was present in the follicular fluid of such follicles. Among the steroid hormones, testosterone was found to be less during the early luteal phase, E 2 and P 4 were located in the theca and granulosa cells as well as in the follicular fluid. The gonadotrophins and steroid hormones were comparatively more in the larger follicles than in the smaller ones. In the late luteal phase, all the gonadotrophins and steroid hormone concentrations were higher than the early luteal phase. FSH was bound on the granulosa and theca cells of mainly the large follicles. LH and PRL were also observed in the theca cells of such follicles. Even the follicular fluid showed an increased localization of these hormones. All the three steroids were observed in the follicular fluid as well as in theca and granulosa cells in a similar patterns during early- and late-luteal phase, except the concentration, which was higher during the late luteal phase. All the enzymes studied were much higher in follicles of the late luteal phase as compared to the early luteal phase ovaries. It may be concluded from this study that there probably are very few gonadotrophin receptors present in the follicular cells during the early luteal phase and hence less steriodogenesis occurred during the early luteal phase compared to the late luteal phase.

Effects of Varying Modes of Perfusion on Ovum Maturation and Ovulation in the Perfused Rabbit Ovary.

Using a perfused rabbit ovary, we studied the effect of luteinizing hormone (LH) secretion on the ovulation time and the maturity of ova with 2 modes of perfusion. One mode consisted of a constant level of human chorionic gonadotropin (hCG) in the medium (the constant mode of perfusion), and the other mode mimicked the profile of LH surge in the rabbit (the surge mode of perfusion). The mean numbers of ova ovulated in the 2 modes were almost equal. The mean ovulation time in the constant mode was shorter than that in the surge mode. In the constant mode, the percentage of ova in germinal vesicle stage was larger, and in metaphase II was smaller, than those in the surge mode, while the difference in metaphase I was insignificant. The results indicate that the maturities of the ova in the surge mode were more advanced than those in the constant mode. A reason for the occurrence of the difference might be the early occurrence of ovulation in the constant mode due to excessive action on the follicular wall by various proteolytic enzymes, which are activated by the higher concentration of hCG, when compared with that of the surge mode, in the latter half of the perfusion.

Atrial Natriuretic Factor Activates Cyclic Adenosine 3′,5′-Monophosphate Phosphodiesterase in Xenopus Laevis Oocytes and Potentiates Progesterone-Induced Maturation via Cyclic Guanosine 5′-Monophosphate Accumulation

Xenopus oocytes were found to express atrial natriuretic factor (ANF) receptors that activate guanylate cyclase and stimulate cyclic guanosine 5'-monophosphate (cGMP) production in a dose- and time-dependent manner. A truncated fragment of ANF, known to bind to mammalian ANF receptors without stimulating cGMP accumulation, did not elicit a cGMP response in oocytes. In addition, preincubation with ANF increased the number of oocytes that underwent progesterone-induced maturation. The maximally effective dose of ANF (1 microM) elevated intracellular and extracellular cGMP accumulation from 50 to 200 and 5 to 800 fmol/oocyte, respectively, and increased the number of maturing oocytes by up to 3-fold. ANF's effects on progesterone-induced maturation were mimicked by nonhydrolyzable analogues of cGMP. ANF and 8-Br-cGMP had no effect on maturation in the absence of progesterone, indicating that elevation of cGMP alone is not sufficient to induce maturation. Dibutyryl-cGMP was as effective as 8-Br-cGMP, whereas 8-Br-guanosine monophosphate, 8-Br-guanosine, and 8-Br-cyclic inosine monophosphate did not potentiate ovum maturation. In Xenopus oocytes, an initial step in progesterone-induced maturation is the reduction of intracellular cAMP levels; both ANF and 8-Br-cGMP lowered cAMP levels and enhanced progesterone's ability to do so. This decrease in cAMP levels was attributable to increased cAMP-phosphodiesterase activity, which was enhanced by both ANF and 8-Br-cGMP. These findings, and the presence of functional ANF receptors on Xenopus oocytes, demonstrate that ANF can participate in ovum development by stimulation of cGMP accumulation and activation of cAMP phosphodiesterase, thereby potentiating progesterone's ability to decrease cAMP levels and promote ovum maturation.

Two-Way Selection for Threshold Body Weight at First Egg in Broiler Strain Females.: 3. Reproductive Performance Under Various Levels of Feed Restriction

Two-way selection was carried out for high and low threshold body weight at onset of lay (ThrWtLay). The present study determined the effect of this selection on reproductive performance under conditions of quantitative feed intake restriction. Female chicks of the two lines were raised under a commercial feed restriction program until 22 wk of age (target weight 2,200 g). At this time they were divided into five treatment groups, one of which had free access to feed, the others receiving 120, 130, 140, and 150 g/day of a commercial layer mash, respectively. The experiment was carried out in two independent replicates, in consecutive years. In all treatments, low-line birds entered lay at a significantly lower body weight and earlier age than the high-line birds. During the prepeak laying period, the early entry into lay of the low-line birds resulted in significantly greater egg numbers as compared with the high-line birds (P < .01). This difference was maintained in the postpeak laying period (34 to 58 wk). When averaged over all treatments and both replicates, the low-line birds produced 70% more eggs than the high-line birds in the prepeak period, 14% more during the postpeak period, and 25% more overall. Over all treatments and both replicates, egg weight of the high-line birds averaged 2.7 g greater than that of the low-line birds. At each feeding level, low-line birds at the end of lay had lower carcass weight and breast weight, and shorter shank length, but a greater absolute weight of abdominal fat than high-line birds. Thus, low-line birds were characterized by increased adiposity. It is hypothesized that the selection implemented in these lines acted primarily to decrease photoperiodic drive of the high-line relative to the low-line birds. This resulted in an increase in the number of days of light stimulation required for initiation and completion of ovum maturation and ovulation by the high-line as compared to the low-line birds. A similar decrease in photoperiodic drive may be at the root of current broiler breeder reproductive problems. If so, selection for low ThrWtLay may be a means of ameliorating these difficulties.