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PubMed2001

Effects of supplementation with free radical scavengers on the survival and fertilization rates of mouse cryopreserved oocytes.

BACKGROUND: This study was conducted to investigate the effects of supplementation with free radical scavengers on the survival and fertilization rates of freeze-thawed mouse oocytes. METHODS: Superovulated oocytes with cumulus cells were cryopreserved by slow freezing in propanediol combined with a rapid thawing protocol. The cryopreservation medium was supplemented with the antioxidant enzymes superoxide dismutase (SOD) and catalase, and with the nitric oxide (NO) scavenger, haemoglobin (Hb). RESULTS: The addition of 50 IU/ml SOD showed significantly higher survival and fertilization capabilities compared with control (P < 0.01). Oocyte survival was greatly increased by concomitant addition of SOD with 10 IU/ml catalase (P < 0.01). On the other hand, the NO donor (sodium nitroprusside) inhibited survival and fertilization rates (P < 0.05). Significantly decreased survival and fertilization rates were also observed following the addition of high concentrations (10(-3) to 10(-6) nmol/l) of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). In contrast, significantly better oocyte survival and fertilization rates were detected with low concentrations (10(-7) nmol/l) of L-NAME. Oocyte survival potential was significantly increased by addition of Hb (1 microg/ml, P < 0.05). Moreover, oocyte survival and fertilization rates were significantly promoted by the concomitant addition of SOD with Hb (P < 0.01). CONCLUSIONS: These results suggest that supplementation of free radical scavengers, particularly combinations of SOD with NO scavengers in freezing and thawing media, improved the post-thaw survival and fertilization rates of cryopreserved mouse oocytes.

Animals↗
PubMed2002

Changes with age in the level and duration of fertility in the menstrual cycle.

BACKGROUND: Most analyses of age-related changes in fertility cannot separate effects due to reduced frequency of sexual intercourse from effects directly related to ageing. Information on intercourse collected daily through each menstrual cycle provides the data for estimating day-specific probabilities of pregnancy for specific days relative to ovulation, and these estimates allow unconfounded analysis of ageing effects. METHODS: A total of 782 healthy couples using natural family planning methods contributed prospective data on 5860 menstrual cycles. Day of ovulation was based on basal body temperature measurements. Estimates of day-specific probabilities of pregnancy and the length of the fertile window were compared across age groups. RESULTS: Nearly all pregnancies occurred within a 6 day fertile window. There was no evidence for a shorter fertile window in older men or women. On average, the day-specific probabilities of pregnancy declined with age for women from the late 20s onward, with probabilities of pregnancy twice as high for women aged 19-26 years compared with women aged 35-39 years. Controlling for age of the woman, fertility was significantly reduced for men aged >35 years. CONCLUSIONS: Women's fertility begins to decline in the late 20s with substantial decreases by the late 30s. Fertility for men is less affected by age, but shows significant decline by the late 30s.

Adult↗
PubMed2005

Association between sequence variations in genes encoding human zona pellucida glycoproteins and fertilization failure in IVF.

BACKGROUND: The zona pellucida (ZP) has multiple roles in reproductive processes, including oocyte maturation, fertilization and implantation. We used, for the first time, a genetic approach to study whether human ZP genes possess structural alterations in women with unsuccessful IVF trials. In theory, this may result in gradual reduction of sperm-zona interaction and eventually in total fertilization failure (TFF). METHODS: Eighteen infertile women (TFFs) whose IVF did not result in any fertilized oocytes, whereas fertilization by ICSI was successful, were screened for mutations in ZP genes by means of conformation-sensitive gel electrophoresis. Twenty-three fertilizers in IVF (FIVFs) and 68 women with proven fertility (WPFs) constituted the two control groups. RESULTS: Altogether, 20 sequence variations were found in the ZP genes. Two variations in ZP3, one in the regulatory region (c. 1-87 T --> G) and one in exon 6 [c. 894 G --> A (p. K298)] existed more frequently in TFFs than in FIVF and WPF groups (P-values 0.027 and 0.008, respectively). CONCLUSIONS: Our study on ZP genes of infertile women revealed a high degree of sequence variations. This may reflect gradual reduction of fertility among TFFs, but the putative roles and influences of single variations can only be hypothesized.

Adult↗
PubMed2005

Treatment option for sperm- or oocyte-related fertilization failure: assisted oocyte activation following diagnostic heterologous ICSI.

BACKGROUND: Failed fertilization occurs in 2-3% of ICSI cycles and is mainly due to lack of oocyte activation. Heterologous ICSI of patient's sperm in mouse oocytes allows discrimination between sperm- and oocyte-related aetiologies of activation failure. Assisted oocyte activation (AOA) by Ca-ionophore treatment can initiate fertilization in subsequent therapeutic ICSI. We report on diagnosis and clinical treatment in 17 patients with previously failed fertilization. METHODS: Sperm from patients were injected into mature mouse oocytes. Activation capacity was assessed by 2-cell formation (mouse oocyte activation test, MOAT). When no activation occurred, it was assumed that the spermatozoon was deficient; otherwise an oocyte-related factor was suspected. In a subsequent ICSI cycle, AOA was done by ICSI with CaCl2 followed by a Ca2+ ionophore exposure. Fertilization was checked 16-20 h later. Embryo transfer was on day 2 or 3. RESULTS: MOAT showed sperm-related activation deficiency in six globozoospermic patients and two patients with extreme oligoasthenoteratozoospermia. One patient with small sperm acrosomes had a normal activation percentage. In eight other patients, the MOAT revealed a relatively normal activation capacity of the sperm, indicating an oocyte-related defect. After AOA, fertilization rates were 77 and 71% in the sperm- and oocyte-related groups respectively. Five pregnancies were achieved in the globozoospermia group and three in cases of oocyte-related activation failure. CONCLUSIONS: Assisted oocyte activation enables normal fertilization and pregnancy in sperm- and oocyte-related fertilization failure.

Acrosome↗
PubMed2006

Localization of arabinogalactan proteins in egg cells, zygotes, and two-celled proembryos and effects of beta-D-glucosyl Yariv reagent on egg cell fertilization and zygote division in Nicotiana tabacum L.

Arabinogalactan proteins (AGPs) have been implicated in a variety of plant development processes including sexual plant reproduction. As a crucial developmental event, plant sexual reproduction generally occurs inside an ovule embedded in an ovary. The inaccessibility of the egg cells, zygotes, and embryos has hindered our understanding of the importance of AGPs in the early events involving fertilization, zygotic division, and early embryogenesis. In this study, the well-established in vitro zygote and ovary culture systems, together with immunofluorescence and immunogold labelling techniques, were employed to investigate the role of AGPs in the early events of sexual reproduction in Nicotiana tabacum. Dramatic changes in AGP content during ovule development were evidenced by western blotting. Subcellular localization revealed that AGPs are localized in the plasma membrane, cell wall, and cytoplasm of pre- and post-fertilized egg cells, and cytoplasm and vacuoles of two-celled proembryos. Abundant AGPs were detected in unfertilized egg cells; however, the level of AGPs substantially decreased in fertilized egg cells. Polar distribution of AGPs in elongated zygotes was observed. The early two-celled proembryos just from zygote division displayed accumulation of AGPs at a low level, while in the elongated two-celled proembryos at the late stage, the AGP content clearly increased. Provision of betaGlcY, a synthetic phenylglycoside that specifically binds AGPs, to the in vitro cultures of isolated zygote and fertilized ovaries increased abnormal symmetrical division of zygotes. In the culture of pollinated but unfertilized ovaries, addition of betaGlcY resulted in arrest of fertilization of the egg cells, but had no effect on fertilization of the central cells. The possible roles of AGPs in fertilization, zygotic division, and proembryo development are discussed.

Cell Division↗
PubMed1988

Selective fertility and the distortion of perinatal mortality.

Data from the Medical Birth Registry of Norway, covering more than one million births for the period 1967-1984, were used to study the magnitude and effects of selective fertility, which is the tendency for a woman to replace a perinatal loss. Variation in fertility after the first three births is studied, controlling for perinatal outcome of previous births, maternal age, and year of birth. Even after the first birth, fertility is higher after a perinatal loss. Selective fertility is more strongly present at each successive birth order, and at each birth order it is stronger among older women. As the average number of births per woman decreases, the force of selective fertility increases; that is, its importance has increased over time. Perinatal mortality at the third and fourth birth orders is particularly distorted by the mechanism of selective fertility in studies based on cross-sectional data. Mortality at second birth is exaggerated by 1%, at third birth by 8% to 20%, and at fourth birth by 18% to 27%, with the largest effects seen in the later periods. A major portion of the increase in perinatal mortality from the second to fourth birth seen in most studies based on cross-sectional data can be explained by the mechanism of selective fertility.

Adult↗
PubMed1996

The effect of chromatin condensation (aniline blue staining) and morphology (strict criteria) of human spermatozoa on fertilization, cleavage and pregnancy rates in an intracytoplasmic sperm injection programme.

The main purpose of this study was to determine the possible relationship between chromatin condensation (Aniline Blue staining), the morphology of spermatozoa according to strict criteria, and the fertilization, cleavage and pregnancy rate in an intracytoplasmic sperm injection (ICSI) programme. A total of 60 patients were divided into two groups (27 versus 34) according to sperm stainability by Aniline Blue. The first group involved patients having a positive Aniline Blue staining test with 0-29% stained. The fertilization rate in this group was 60.8%, cleavage rate 54.4% and pregnancy rate 18.5%. In the second group in which > 29% spermatozoa were positively stained, the fertilization rate was 62.1%, cleavage rate 62.0% and pregnancy rate 35.3%. There was no statistically significant difference between the two groups. Furthermore, the influence of morphology according to strict criteria after Papanicolaou staining on successful fertilization, cleavage and pregnancy was studied in 85 patients who were divided into two groups according to the percentage of morphologically normal sperm. The fertilization, cleavage and pregnancy rates were 44.21, 63.37, and 39.47% respectively in the first group (< 4%), the corresponding values for the second group (> 4%) were 56.50, 46.04 and 21.21%. There was no significant correlation between the fertilization (P = 0.722), cleavage (P = 0.519) and pregnancy (P = 0.096) rates in either group. This study demonstrates that neither chromatin condensation (Aniline Blue staining) nor morphology could assess the fertilization potential, cleavage and pregnancy rate in an ICSI programme.

Aniline Compounds↗
PubMed1996

Aggressive sperm immobilization prior to intracytoplasmic sperm injection with immature spermatozoa improves fertilization and pregnancy rates.

This study was conducted to determine whether the mode of sperm immobilization prior to intracytoplasmic sperm injection (ICSI) influences fertilization by immature spermatozoa. Of the 837 ICSI cycles evaluated, 81 were performed with epididymal or testicular spermatozoa; 35 cycles with epididymal spermatozoa immobilized in the standard fashion resulted in fertilization and pregnancy rates of 48.3 and 51.4% respectively. When a more aggressive sperm immobilization technique (i.e. permanently crimping the sperm flagellum between the midpiece and the rest of the tail) was applied in 17 cycles, the resultant fertilization and pregnancy rates were significantly (P < 0.05) higher: 82.0 and 82.4% respectively. Similar increases in fertilization and ensuing pregnancy rates were also observed in ICSI cycles with the aggressive immobilization of frozen-thawed epididymal spermatozoa (eight cycles) versus standard immobilization (16 cycles). However, the fertilization rates for ICSI using testicular spermatozoa (five cycles) were basically the same, regardless of the immobilization technique. Furthermore, for ejaculated spermatozoa (756 cycles), the fertilization rates following aggressive sperm immobilization were also positively affected (73.4%), although no statistical differences in the clinical pregnancy rates were found. Because aggressive immobilization appears to affect sperm membrane permeabilization, the enhanced fertilization patterns observed in immature spermatozoa following aggressive immobilization may suggest a different membrane constitution in these spermatozoa. These findings indicate that immature gametes may require additional manipulation to enhance the post-ICSI events essential for adequate nuclear decondensation.

Adult↗
PubMed1996

Prediction of the in-vitro fertilization (IVF) potential of human spermatozoa using sperm function tests: the effect of the delay between testing and IVF.

To examine the diagnostic significance of several criteria of semen quality and to determine whether their prognostic value is eroded by the time interval between assessment and the attempt at in-vitro fertilization (IVF) with embryo transfer, 73 couples undergoing IVF and embryo transfer therapy were studied. The ability of human spermatozoa to achieve fertilization in vitro was examined in relation to the conventional semen profile, sperm morphology, the computer-aided assessment of sperm movement, ionophore-induced acrosome reaction, acridine orange staining, and chemiluminescent signals induced by phorbol ester and N-formyl-methionyl-leucyl-phenylalanine (FMLP). Spermatozoa were examined both in semen and after preparation on Percoll, some weeks prior to IVF. Fertilization rates were noted to be significantly correlated with elements of sperm movement characteristics, sperm morphology, and reactive oxygen species generation. Prediction of fertilization rates in a stepwise multiple regression analysis was obtained using four variables: sperm morphology, FMLP-induced chemi-luminescence and sperm movement characteristics (beat cross frequency and straightness) (r approximately 0.5). When multiple logistic regression analysis was used to predict which samples would achieve fertilization rates above and below a 50% threshold, three variables of predictive value including linearity, average path velocity and FMLP-induced chemiluminescence were selected. Combination of these variables classified the samples achieving good or poor fertilization with an overall accuracy of 83.6%. The time interval between semen assessment and IVF had little effect on the predictive value of these tests. In conclusion, the fertilizing ability of human spermatozoa is related to sperm morphology, attributes of sperm movement and reactive oxygen species production. The time delay between testing and IVF did not appear to affect predictive accuracy.

Acridine Orange↗
PubMed1996

Semen parameters as predictors of in-vitro fertilization: the importance of strict criteria sperm morphology.

This study evaluated 120 couples undergoing in-vitro fertilization treatment to determine which semen parameter(s) predicted fertilization and whether there was any consistent relationship between strict criteria and standard assessment of sperm morphology. Strict criteria morphology was the only significant predictor of fertilization (P = 0.0006, r2 = 0.09), with a sensitivity of 94% and a specificity of 40%. A 12% cut-off point presented a negative predictive value of 98% and a positive predictive value of 22%. The probability of satisfactory fertilization is 40% with morphology <4%, which increases to 97% with normal morphology (>=12%). The receiver operating characteristic curve deviated significantly from the diagonal with a 76% area under the curve, making this a superior predictive test. This was augmented by likelihood ratios (LR) of 8. 25 (LR+) for results with <4% normal morphology and 0.15 (LR-) for results with >/= 12% normal morphology by strict criteria. While there was some correlation between strict criteria and standard assessment of morphology (r = 0.35), the former explained only 12% (r2 = 0.12) of the variability in the latter. This study concludes that strict criteria morphology predicts fertilization, while other semen parameters do not. A 12% cut-off point makes strict criteria morphology an excellent predictor of satisfactory fertilization, while a value <4% is a good predictor of poor fertilization.

Cohort Studies↗
PubMed1991

Predictive value of classical and automated sperm analysis for in-vitro fertilization.

The fertilization rates observed in 122 attempts at in-vitro fertilization were examined in relation to sperm characteristics assessed by visual and automated screening. Using linear regression analysis, a significant correlation was found between the fertilization rate and (i) evaluations in fresh semen sperm concentration, percentages of sperm motility, vitality and normal morphology and velocity, (ii) measurements in swim-up preparations of percentages of sperm motility, vitality and morphology, velocity and amplitude of lateral head displacement. No significant correlation was found between the fertilization rate and any of the parameters studied in 24-h-old swim-up suspensions. Analysis by multiple variable stepwise linear regression showed an optimal correlation (R6 = 0.62) between the observed fertilization rate and theoretical calculation obtained from the following predictive function: fertilization rate = -0.3 + (0.008 x swim-up motility) + (0.004 x normal sperm morphology in fresh semen). Introduction of kinematic characteristics studied by automated screening improved the multiple correlation between the calculated and observed fertilization rate in cases of normal or mildly defective semen. Because of the limited availability of motile spermatozoa, automated analysis could not supersede classical sperm analysis in cases of more severe sperm defects.

Autoanalysis↗
PubMed1992

The Acridine Orange test: determining the relationship between sperm morphology and fertilization in vitro.

The prediction of human fertilization is an important aspect of research protocols dealing with male fertility. Sperm DNA has been reported to be an indicator of human sperm fertility potential. The Acridine Orange test for evaluation of sperm DNA has been employed during the present study to determine its relationship with human sperm morphology and fertilization in vitro. Seventy-six patients from the in-vitro fertilization (IVF) and/or gamete intra-Fallopian transfer (GIFT) programme were randomly selected for the study. All patients had a routine semen analysis, sperm DNA evaluation and underwent standard IVF procedures at the time of the study. The results indicated a moderate positive correlation (r = 0.38, P = 0.0006) between results of the Acridine Orange test and normal sperm morphology. Patients with an Acridine Orange test value exceeding 24% had significantly higher oocyte fertilization rates than patients with lower values, for metaphase I (74 versus 51%, P = 0.0008) and for metaphase II oocytes (88 versus 60%, P = 0.0001). Sperm morphology, however, proved to be a more significant predictor of fertilization in vitro compared to the Acridine Orange test.

Acridine Orange↗
PubMed1993

In-vitro fertilization in the presence of antisperm antibodies detected by the mixed antiglobulin reaction (MAR) and the tray agglutination test (TAT).

Data from 33 couples suffering from male immune infertility, who underwent 47 in-vitro fertilization (IVF) cycles between January 1989 and August 1991, were retrospectively analysed. The serum of all the 33 male partners had elevated tray agglutination test (TAT) titres (> or = 1:16) and positive mixed antiglobulin reaction (IgG MAR) test results in their semen. There was a slight correlation between these tests in semen and serum. Fertilization rates were analysed in three sperm MAR subcategories. Only the strongly positive MAR group (values > or = 90%) revealed a significant reduction in fertilization rate compared to the other MAR groups. However, this was not observed with increasing serum TAT titres. Fertilization rates were decreased in asthenozoospermic (20.1%) compared to normozoospermic (34.0%) male partners. This occurred also with couples not affected by immunological factors, but when antisperm antibodies were present, the fertilization rates were significantly poorer irrespective of whether the sperm motility was normal or decreased. Once fertilization occurred, the pregnancy rate was not affected by the severity of immunological factors. In assisted reproduction the sperm preparation techniques may reduce the inhibiting effects of antibodies bound to the spermatozoa, and when there are several oocytes to be inseminated, the chance of fertilization rises.

Adult↗
PubMed1994

The effect of pentoxifylline on mouse in-vitro fertilization and early embryonic development.

This study was designed to assess the effect of pentoxifylline (PTX) on fertilization and early embryonic development in the mouse. Oocytes from superovulated B6CBA female mice were inseminated in vitro with spermatozoa from B6CBA males incubated with PTX according to different protocols, i.e. (i) 3.6 and 7.2 mM PTX washed out prior to insemination, (ii) 3.6 and 7.2 mM PTX diluted six times in the insemination medium and (iii) PTX present at 3.6 and 7.2 mM in the insemination medium. After insemination and washing, fertilization was assessed by the presence of 2-cell stage embryos. These were further cultured up to the blastocyst or egg-cylinder stage to assess embryonic development. Parthenogenetic activation was evaluated by exposing post-ovulatory oocytes to 3.6 and 7.2 mM PTX. If spermatozoa were washed free from PTX before insemination, no effect on either fertilization or subsequent development was found. If PTX was not washed out, fertilization was reduced significantly, yet development of fertilized oocytes was unaffected. If insemination was performed in the presence of PTX both fertilization and development were impaired. Parthenogenetic activation was not increased by PTX exposure. We conclude that if used in in-vitro fertilization, exposure of oocytes and/or zygotes to PTX has to be avoided by washing out the compound thoroughly to prevent adverse effects on early embryonic development.

Animals↗
PubMed1999

Effects of the tricothecene mycotoxin diacetoxyscirpenol on fertility and hatchability of broiler breeders.

Two experiments were conducted to determine the effects of 4,15-diacetoxyscirpenol (DAS) on fertility and hatchability of broiler breeders. In Experiment 1, naturally mated broiler breeders were studied. A limited daily allocation of feed containing 0 (basal), 1.25, 2.5, or 5.0 mg DAS/kg diet was provided from 67 to 69 wk of age in slat-litter floor pens. Fertility was consistently improved by the 5.0 mg/kg level of DAS and intermittently by the 1.25 and 2.50 mg/kg levels. The effect disappeared upon removal of DAS. In Experiment 2, individually caged broiler breeder males and females were fed a basal diet containing 0, 5, 10, or 20 mg DAS/kg diet from 25 to 27 wk of age. Semen was pooled from males within each treatment and used to inseminate females from each treatment in a 4 x 4 factorial design. Female-related fertility was increased at the 5 and 10 mg DAS/kg levels and male-related fertility was decreased by the 10 and 20 mg DAS/kg levels. Small, fluid-filled cysts were observed on the testes of many DAS-treated males upon necropsy. In summary, low levels of DAS (< or =10 mg DAS/kg) appeared to improve female-related fertility, presumably because of enhanced spermatozoal storage within the oviduct. Conversely, DAS (> or =10 mg DAS/kg) decreased male-related fertility, presumably by direct toxic effects on the testes. Overall, it appeared that levels of DAS below 5 mg DAS/kg feed would not be detrimental to fertility and hatchability.

Animal Feed↗
PubMed2000

Use of a sperm analyzer for evaluating broiler breeder males. 2. Selection of young broiler breeder roosters for the sperm quality index increases fertile egg production.

Previous research has shown that the sperm quality index (SQI) of rooster semen is indicative of overall semen quality. The objectives of the present experiments were to determine the correlation of the SQI with semen characteristics and fertility and to determine if selection of young males for the SQI would improve fertility. In Experiment 1 semen was collected from 35 Peterson males and was analyzed individually for sperm concentration and viability. To determine fertility, 100 microL of diluted semen was inseminated into 10 hens for each rooster. Positive correlations of the SQI with total and live sperm concentrations as well as fertility were found. A negative correlation of the SQI with the percentage of dead sperm was observed. In Experiment 2, four semen samples were collected at 2- to 3-d intervals from each of 142, 27-wk-old Peterson roosters to determine their SQI. Males were then allocated to six treatment groups based on their average SQI readings as follows: 0 to 150, 151 to 200, 201 to 250, 251 to 300, 301 to 350, and >350. For each SQI group, semen was collected weekly for 8 wk, pooled, and used at a rate of 50 microL/hen to inseminate 40 hens. The percentage of fertilized eggs increased linearly across the SQI groups, from a minimum of 65% for the 0 to 150 SQI group to a maximum of 98% for the >350 SQI group. The SQI groups of 301 to 350 and >350 produced the slowest decline in fertility over days postinsemination. Therefore, selection of males for the SQI at an early age appears to improve flock fertility.

Animals↗
PubMed2004

An effective method for improving the fertility of glycerol-exposed poultry semen.

Semen cryopreservation is necessary for banking germplasm from critical poultry stocks. To date, glycerol is the most effective cryoprotectant for poultry sperm; however, the contraceptive effects of glycerol require a significant reduction of the cryoprotectant from thawed semen before artificial insemination (AI). The effectiveness of glycerol reduction by dialysis, Percoll density gradient centrifugation, or washing through 12% (wt/vol) Accudenz was evaluated by fertility trials with highly inbred chicken research lines and commercial turkey lines. Semen was extended 1:1 and then diluted with glycerolized extender to yield a final 11% (vol/vol) glycerol concentration. Glycerolized rooster semen was aliquoted for control, Accudenz centrifugation, and dialysis treatments. A total of 90 pure line and 85 F1 hybrid chicken hens were each inseminated with 100 x 10(6) sperm at 7-d intervals for 4 to 6 wk. All eggs from the glycerolized control semen treatments were infertile, and fertility rates from dialyzed semen decreased steadily from 26.4 to 0% within the first 4 wk for the pure lines. In contrast, fertility rates for Accudenz-processed semen increased from 17.9 to 37.17% during the first 4 wk. Similar fertility rates occurred with the F1 hybrid cross lines. For turkey fertility trials, the dialysis treatment was not used; glycerolized turkey semen was processed by Accudenz or Percoll centrifugation to reduce glycerol. A total of 36 hens were inseminated with 150 x 10(6) sperm at 7-d intervals for 6 wk. Similar to the chicken trials, fertility rates of Accudenz-processed semen steadily increased to 49.4% by the sixth week of insemination. The average fertility of Percoll-processed semen was only 19.1%. These data demonstrate that Accudenz centrifugation is an acceptable glycerol reduction method for nonfrozen poultry semen.

Animals↗
PubMed2007

Feeding broiler breeder males. 1. Effect of feeding program and dietary crude protein during rearing on body weight and fertility of broiler breeder males.

A 2 x 2 factorial experiment was conducted to compare the effects of 2 male broiler breeder feed allocation programs (Concave or Sigmoid) during the rearing period to 26 wk of age and the interaction with dietary CP (12 or 17%) on BW and fertility. From 0 to 2 wk, all birds received a starter diet, after which, pens were randomly assigned to the 4 treatment combinations that ended at 26 wk of age. All males were weighed individually at 4, 8, 12, 16, 22, 26, 28, 32, 36, 40, 48, 52, 56, and 64 wk of age, and fertility was determined weekly from 27 to 32 wk of age and then every 2 wk to 64 wk of age. At 49 wk of age, the male feed allocation for all treatments was increased by 5 g/d. Even when fed the same as Sigmoid program males during the production period, males reared on the Concave feeding program lost BW from 32 to 40 wk of age and exhibited lower BW from 40 to 48 wk of age, which corresponded to a more rapid decrease in fertility. The 17% CP diet increased BW from 8 to 32 wk of age, but no significant differences were subsequently observed. The 12% CP rearing diet improved both weekly and cumulative fertility. A significant interaction between rearing feeding program and dietary CP during the third quartile period showed that the Concave program-17% CP diet combination was most negatively affected. The increase in male feed allocation at 49 wk restored fertility and caused differences among treatments to diminish. These data suggested that BW during the early rearing period did not affect fertility, but an increased BW due to either providing fast feed increments toward the end of the rearing period (Concave) or feeding a 17% CP diet produced males that were unable to sustain fertility after 40 wk of age without an appropriate allocation of feed.

Animal Feed↗