Measures Of Reproductive Performance Research Articles

Performance of a Swedish deep-bedded feeder pig production system in Iowa

AbstractAt the Iowa State University Armstrong Research and Demonstration Farm in southwestern Iowa, a Swedish feeder pig production system was studied and demonstrated for 2-1/2 years. The system is based mainly on straw bedding, simple buildings, and intensive management. The system was designed to minimize pig stress and use of subtherapeutic antibiotics in the feed. Gestating and breeding sows were group-housed in a hooped structure with individual feeding stalls. Large round bales of cornstalks were used for bedding. Farrowing, lactation, and nursery phases were housed in a remodeled hog house. Cubicles with rollers and oat straw bedding were used for farrowing. Two groups of Yorkshire × Landrace sows bred to Hampshire boars produced feeder pigs in the system. Conception rates averaged 95%, and litter size averaged 11.3 live pigs/litter. Sows were allowed to select their own bedded farrowing cubicle. Prewean pig mortality, mostly from crushing, was high (29%), occurring primarily in the first 3 days. At 2 weeks of age the cubicles were removed and group lactation occurred. After group lactation the average pig weaning weight was 10.4 kg at 33.9 days of age. At weaning the sows were removed, and the pigs remained in the bedded farrowing/lactation room for 24 additional days. The pigs weighed 24.8 kg at 60 days of age, and overall nursery phase average daily weight gain was 549 g/day. Overall pig health was excellent with no major clinical diseases confirmed. The demonstration exceeded reproductive performance measures of typical small- and mid-sized Iowa farms.

Effect of one spontaneous estrus cycle (after synchronization with PGF 2α) on reproductive performance in dairy cows

The objective of the study was to analyze the effect of a spontaneous estrus cycle after synchronization of estrus with prostaglandin F 2α (PGF 2α) in dairy cows on the degree of synchronization and reproductive performance. We assigned 557 Holstein cows to two treatment groups. In Group 1 estrus was synchronized by two treatments with 25 mg of Dinoprost-Trometamol in 14-day intervals. Cows were treated 27 to 33 days postpartum (dpp) and 41 to 47 dpp, respectively. Cows in Group 2 were treated with 25 mg of Dinoprost-Trometamol three times in 14-day intervals, starting at 34 to 40 dpp. The second and third injections were administered at 48 to 54 dpp and 62 to 68 dpp, respectively. All cows were inseminated on observed estrus after a voluntary waiting period of 65 days post partum. Thus cows in Group 1 were inseminated on spontaneous estrus and cows in Group 2 on induced estrus. Cows not inseminated at 80 days post partum were palpated per rectum and treated according to a predefined protocol. Herd reproductive performance measures did not differ significantly between groups. The proportion of cows with low serum progesterone levels was significantly higher 3 days after synchronization than 24 days after synchronization (97% vs 39%). The first-service conception rate was 34.8% in Group 1 and 30.7% in Group 2 (P>0.05). Days open were 113.5 in Group 1 and 110.9 in Group 2 (P>0.05). It is concluded that postponing artificial insemination for one spontaneous estrus cycle after synchronization decreased the degree of synchronization. This procedure, however, had no effect on herd reproductive performance compared to insemination on first observed estrus after synchronization.

Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility

AbstractReproductive performance of 714 Holstein Friesian dairy cows was monitored between October 1995 and June 1998 using thrice weekly milk progesterone determinations. Defined endocrine parameters such as interval topost-partumcommencement of luteal activity, inter-ovulatory interval and length of luteal and inter-luteal intervals were used with a number of traditional measures of reproductive performance to investigate the current status of fertility in a sample of United Kingdom dairy herds. A comparison of the results of the 1995 to 1998 trial with those of a previous (1975 to 1982) milk progesterone database, which included 2503 lactations in British Friesian cows monitored using a similar milk sampling protocol, revealed a decline infertility between these periods.Between 1975-1982 and 1995-1998, pregnancy rate to first service declined from 55·6% to 39·7% (P< 0·001), at a derived average rate approaching 1% per year. This decline was associated with an increase (P< 0·001) in the proportion of animals with one or more atypical ovarian hormone patterns from 32% to 44%. There was a significant (P< 0·001) increase in the incidence of delayed luteolysis during the first cyclepost partum(delayed luteolysis type I; 7·3% to 18·2%) and during subsequent cycles (delayed luteolysis type II; 6·4% to 16·8%), although the incidence of prolonged anovulation post partům (delayed ovulation type I; 10·9% to 12·9%) and prolonged inter-luteal intervals (delayed ovulation type II; 12·9% to 10·6%) did not alter significantly. These changes resulted in an increase in mean luteal phase length from 12·9 (s.e. 0·09) to 14·8 (s.e. 0·17) days and an increase in inter-ovulatory interval from 20·2 (s.e. 0·1) to 22·3 (s.e. 0·2) days. The decline infertility was also reflected in traditional measures of fertility since although interval to first service remained relatively unchanged (74·0 (s.e. 0·4) to 77·6 (s.e. 1·1) days) calving interval lengthened from 370 (s.e. 2·2) to 390 (s.e. 2·5) days. Collectively these changes may have contributed to the decline in pregnancy rates observed over the last 20 years.

Heritabilities of reproductive traits in a beef cattle herd using multitrait analysis

Extracted from text ... Heritabilities of reproductive traits in a beef cattle herd using multitrait analysisR.R. van der Westhuizen 1 , S.J.Schoeman 1 , G.F. Jordaan 1 and J.B. van Wyk 21 Dept of Animal Science, University of Stellenbosch, P Bag X1, Matieland, 76022 Dept of Animal Science, University of Orange Free State; P O Box 339,Bloemfontein, 9300IntroductionReproduction is a critically important aspect of overall efficiency in the livestock industry. However,reproduction is a complex process with many components. Several such components have been used as measuresof reproductive performance. Calving interval (CI), calving rate, services per conception, age at first calving(AFC), days to calving and ..

Jasmonate-induced responses of Nicotiana sylvestris results in fitness costs due to impaired competitive ability for nitrogen.

We present the first evidence for a fitness cost of an inducible response that is detectable in a nitrogen (N) currency. Nicotine is an induced defense in Nicotiana sylvestris that can utilize 5–8% of the plant's total N, an investment that apparently cannot be recouped by metabolism. Induced nicotine production is endogenously regulated by jasmonic acid (JA), and we treated leaves with the methyl ester of this wound hormone (MeJA) in quantities (0, 25, 250 μg) known to elicit changes in endogenous JA and subsequent nicotine responses comparable to those elicited by mechanical wounding and herbivory in this species. We grew plants in competition chambers (CCs) in which three same-sized plants could compete for a communal but fixed pool of 15NO3 to quantify the outcome of competition for this fitness-limiting resource that is used both in defense and seed production. Competition profoundly increased all measures of growth and reproductive performance measured per milligram of N acquired. While plants acquired all the N supplied to them in the hydroponic solution, plants grown in CCs (as compared those grown in individual chambers—ICs) retained more of this N and produced more biomass, had larger nicotine contents, allocated less of their N to nicotine, produced larger floral stalks with more flowers, aborted fewer flowers, matured more capsules, and produced a greater mass of seed. Plants grown in ICs produced heavier seed, but this difference did not translate into a difference in seed viability.

Effect of a Monensin-Controlled Release Capsule on Cow Health and Reproductive Performance

Dry cows and pregnant heifers from 25 farms near Guelph, Ontario, Canada were enrolled in a large, double-blind, randomized clinical trial designed to evaluate the impact of monensin on energy metabolism, health, and production. A total of 503 cows was given monensin in controlled-release capsules, and 507 cows were administered placebo capsules 3wk before expected calving date. The effects of treatment on health were evaluated using a logistic regression model. Treatment with monensin significantly reduced the incidence of abomasal displacement (OR=0.41 – 0.84) and multiple illnesses (OR=0.38 – 0.89). Monensin treatment tended to reduce the incidence of clinical ketosis (P=0.11) and the risk of being culled (P=0.09) in the first 94 d of lactation. Reproductive performance was analyzed with both a logistic regression model for conception rate and a survival analysis for days to first breeding and days from calving to conception. Treatment with monensin had no significant effect on any measure of reproductive performance.

Multigeneration reproductive toxicity assessment of 60-Hz magnetic fields using a continuous breeding protocol in rats.

Male and female reproductive functions have been proposed as possibly sensitive targets for the biological effects of 60-Hz (power frequency) magnetic fields (MF). However, experimental data relevant to this hypothesized association are very limited. In the present study, the "reproductive assessment by continuous breeding" design was used to identify possible effects of MF exposure on reproductive performance, fetal development, and early postnatal growth in rats. Groups of age-matched Sprague-Dawley rats (40 breeding pairs/group) were exposed continuously (18.5 hr per day) to linearly polarized, transient-free 60-Hz MF at field strengths of 0 Gauss (G; sham control), 0.02 G, 2.0 G, or 10.0 G. An additional group of 40 breeding pairs received intermittent (1 hr on/1 hr off) exposure to 10.0 G fields. F0 breeding pairs were exposed to MF or sham fields for 1 week prior to mating, during a 14-week period of cohabitation, and during a 3-week holding period after cohabitation. The duration of the cohabitation period was selected to be sufficient for the delivery of five litters in the sham control group. Pups from the final F1 litter from each breeding pair were exposed to MF or sham fields until sexual maturity, were cohabitated in MF or sham fields for 7 days with nonsiblings from the same exposure group, and were held in the MF or sham fields for 22 days to permit delivery of F2 pups for evaluation. No evidence of exposure-related toxicity was identified in any rat in the F0, F1, or F2 generations. Fetal viability and body weights in all litters of groups exposed to MF were comparable to those of sham controls. No significant differences between sham controls and MF-exposed groups were seen in any measure of reproductive performance (litters/breeding pair, percent fertile pairs, latency to parturition, litter size, or sex ratio) in either the F0 or F1 generation. Exposure of Sprague-Dawley rats to 60-Hz MF strengths of up to 10.0 G either during their peak reproductive period (F0) or during gestation and throughout their life span (F1) has no biologically significant effects on reproductive performance. These results do not support the hypothesis that exposure to pure, linearly polarized 60-Hz MF is a significant reproductive or developmental toxicant.

Senescence in a short‐lived migratory bird: age‐dependent morphology, migration, reproduction and parasitism

1. Senescence reflects age‐dependent changes in residual reproductive value. Annual survival rates of the barn swallowHirundo rusticaL. increased from 1‐ to 2‐year‐old individuals, but decreased among 5 years old or older individuals. Estimates of age‐dependent reproductive value showed a similar pattern.2.Longitudinal data from two long‐term population studies were used to test whether a number of different measures of performance (condition‐dependent morphological traits, migratory performance, reproductive success, intensity of parasitism) changed among individuals when reaching old age.3.The length of the outermost tail feathers (a secondary sexual character) decreased among old individuals, while two measures of individual developmental instability increased with age. Migratory performance decreased in old barn swallows as reflected by a delay in spring arrival at the breeding grounds. Reproductive performance measured as seasonal reproductive success decreased with age. The intensity of infestations with an haematophagous mite and a mallophagous ectoparasite increased among old barn swallows.4.These results suggest that the condition‐dependent secondary sexual character, developmental stability, and measures of migratory and reproductive performance deteriorated, and the frequency of parasitism increased among old individuals. Ageing was thus associated with a general deterioration of performance.

Evaluation of calving interval and calving date as measures of reproductive performance in a beef herd

Calving interval is currently used as the measure of reproductive performance in South Africa and many other countries, but some authors have claimed that calving interval is not a suitable measure of reproductive performance, when cows are mated during a restricted breeding season. Numerous authors have suggested that calving date is a suitable alternative measure of reproductive performance. This study was undertaken to investigate the factors influencing calving interval and calving date, in order to determine their suitability as measures of reproductive performance under conditions of restricted breeding. Two models were developed, each having the following independent effects: Year of birth, age of dam, previous sex of calf, previous calf birth weight, previous calf weaning weight and previous calving date. A number of interactions were included. In Model 2, gestation length was included as an additional independent effect. The dependent variables were: calving interval and calving date. Year of birth and previous calving date had a highly significant influence on calving interval and calving date whilst age of dam had a highly significant influence on calving interval and a significant influence on calving date. A 1 day delay in previous calving date, resulted in a 0.72 day decrease in calving interval, and a 0.27 day increase in calving date (Model 1). In Model 1, previous calving date was the variable having the greatest influence on calving interval and calving date with previous calving date having a much greater influence on calving interval than on calving date, as determined by the significantly larger mean square associated with calving interval than calving date. When calving interval was corrected for the large negative effect of previous calving date, calving interval and calving date became similar measures. It was concluded that calving interval was a more biased method of evaluating reproductive performance than calving date, when cows are mated during a restricted breeding season, due to the negative relationship between previous calving date and calving interval and that calving date could be a suitable alternative measure of reproductive performance.

Factors affecting reproductive performance in Ontario dairy herds

Data were collected on reproductive, health and production events in 45 dairy herds in southwestern and eastern Ontario, Canada, from July 1990 to July 1993. Mean and median days in milk at first estrus, at first service, and at conception were 85.1 and 83.9, 94.0 and 88.9, and 126.3 and 115.5 d, respectively. The mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. The mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. The most commonly used used therapeutic agents were GnRH (11.5% lactational incidence risk) and PG (13.1% lactational incidence risk). Estrus management accounted for the largest portion of PG use in the herds studied (69.4%). Results of a two sample t-test indicated no significant difference in reproductive performance among herds housed in free-stall compared with those housed in tie-stall barns. Multivariate linear regression models of 3 reproductive performance measures indicated that cows with ovarian cysts and/or increased peak milk production had significantly longer calving-to-first estrus and calving-to-conception intervals as well as lower conception rates than average producing cows without cysts. Cows with metritis were found to have significantly shorter calving-to-conception intervals but no detectable difference in conception rate or calving-to-first estrus interval than their herdmates. As lactation number increased reproductive performance improved. Cows that were observed in estrus earlier conceived earlier. Animals receiving uterine infusions had significantly longer calving-to-conception intervals and lower conception rates than their herdmates. There was no detectable difference in reproductive performance for cows treated with GnRH or PG compared with the nontreated cows. An increased estrus detection rate was associated with shorter calving-to-conception intervals and lower conception rates. Based on the range of performance in the study herds, the factors with the greatest potential influence on calving-to-conception interval in the average herd were the estrus detection rate and conception rate.

Influence of feed intake during individual weeks of lactation on reproductive performance of sows on commercial farms

The influence of average daily feed intake (ADFI) during different weeks of lactation on the reproductive performance of sows was investigated. Data contained 18243 farrowing and 15671 ADFI records for sows with lactation length between 7 and 22 days from 30 commercial farms. The regression coefficients of ADFI during individual 3 weeks of lactation on the three measures of reproductive performance were compared. The coefficients of ADFI on natural log-transformed weaning-to-service interval were larger for week 2 (−0.0529 for parity 1; −0.0579 for parity 2 or greater) than for weeks 1 (−0.0340 for parity 1; −0.0277 for parity 2 or greater) and 3 (−0.0295 for parity 1; −0.0188 for parity 2 or greater). The coefficients of ADFI for weeks 2 (0.6667) and 3 (0.6301) in parity 1 sows on litter weight at weaning were larger than that of week 1 (0.3051). In parity 2 or greater, the coefficient of ADFI for week 3 (1.2787) was intermediate between those for weeks 1 (1.0533) and 2 (1.6956). No differences were found between the coefficients of ADFI during individual weeks on subsequent litter size. It is suggested that increased feed intake during early and mid-lactation reduces weaning-to-service interval more than it does during late lactation, and increased feed intake during mid- to late lactation increases litter-weaning weights more than it does during early lactation.

Seasonal and age variability in the reproductive performance of Penaeus semisulcatus broodstock: optimising broodstock selection

The knowledge of the inherent reproductive patterns of wild prawn (shrimp) populations is essential in predicting the expected performance of hatchery broodstock. In response to problems of variable hatchery performance of penaeid broodstock at some times of the year, the inherent seasonal variability and the effects of broodstock age on reproductive performance of Penaeus semisulcatus were examined. The investigation of these effects, using a penaeid for which the detailed reproductive ecology was well known, provided a proxy from which to describe the general case likely applicable to other farmed species. During the three-year study, assessments were made for broodstock of known but increasing age collected from the wild overall seasons (at 2-monthly intervals), and from the two distinct age-cohorts present in the same season. The reproductive performance of the broodstock was assessed at each stage of the maturation and spawning process. Measures of maturation rate, spawning rate, fecundity, hatch rate, larval survival rate, and larval production rate were obtained. Inherent temporal patterns in the measures of reproductive performance were found for the main annual cohort of the wild stock. The rates of spawning, egg production, nauplii production and protozoeae production were lowest in autumn when females were 6 months old, increased through to a spring peak (at 12 months old), and then declined by early summer by which time females were 14 months old. Broodstock survival, egg hatching and metamorphosis of nauplii to protozoeae were unaffected by time of year. Trials with two age-cohorts present in the same season enabled us to separate the effects of age and season. Twelve-month-old broodstock outperformed 6-month-old broodstock, regardless of season. Age was the best predictor of reproductive performance. An optimal age of 12 months for best reproductive performance was identified. This information can be used to select broodstock for hatchery production. The findings may be applicable to other species of farmed penaeids.

Factors influencing the postweaning reproductive performance of sows on commercial farms

The objective of this study was to investigate the effects of various factors, including lactational feed intake, on the reproductive performance of sows in commercial herds. The 4 measures of reproductive performance were weaning-to-first-service interval, weaning-to-conception interval, litter weight at weaning, and subsequent litter size. Parity, farrowing season, lactation length, farrowing-to-conception interval, litter size, and lactation feed intake were investigated as risk factors common to the 4 measures of post-weaning reproductive performance. Using 4 basic multiple regression models for each measure, the least-square means for sets of factors were compared using the GLM procedure of SAS. Parity 1 sows had the longest weaning-to-first-service interval and weaning-to-conception interval, and the lighter litter weight at weaning (P < 0.05) than mid-parity sows. Sows in Parities 2 to 5 had larger subsequent litter size (P < 0.05) than those in Parities 1 and ≥ 7. Sows farrowing in summer and spring had the longest and second longest weaning-to-conception interval (P < 0.05), respectively, while sows farrowing in summer had longer weaning-to-first-service interval than those that farrowed in spring (P < 0.05). Sows farrowing in summer produced the lightest litter weight at weaning (P < 0.05). No differences in subsequent litter sizes were found due to farrowing season (P > 0.10). As lactation length increased, weaning-to-first-service interval and weaning-to-conception interval decreased, and litter weaning weight increased. Longer lactation length and farrowing-to-conception interval were associated with larger subsequent litter size (P < 0.05). Litter size did not affect weaning-to-first-service interval or weaning-to-conception interval. Larger litter sizes were associated with heavier litter weight at weaning. Greater lactation feed intake improved the 4 measures of reproductive performance.

Ecological Consequences of Nest Site Fidelity in Black Brant

Empirical tests of ecological advantages of site fidelity in birds are few because consequences of dispersal are rarely measured. We examined the relationship between dispersal distance between consecutive nesting attempts and age, nest success, reproductive performance, and spring environment for female Black Brant (Branta hernicla nigricans) nesting colonially at the Tutakoke River, Alaska, 1987-1993. We found little evidence of fidelity to natal sites. Young brant moved towards a peripheral area of the colony. Successfully breeding brant dispersed shorter distances than those failing to nest successfully. Brant that initiated nests early dispersed farther than brant that initiated nests late. Neither nest success nor initiation date in year t + 1 were related to dispersal distance (year t to year t + 1), but clutch size declined with dispersal distance. Although generally not significant, annual variation (interaction) in the relationship between dispersal distance and measures of reproductive performance (i.e., initiation date and clutch size) suggest that this relationship may be influenced by spring weather conditions. Evidence for the advantages of site fidelity in brant was equivocal. Dispersal distance explained little variation associated with reproductive performance. Variation in individual bird quality, environmental conditions, and demographic status may be more important determinants of breeding performance in brant than potential benefits of site fidelity.

Rank and reproduction in the female spotted hyaena

Female reproductive success varies with social rank in many gregarious mammals, including primates, ungulates and carnivores. Social groups of spotted hyaenas (Crocuta crocuta) are structured by hierarchical dominance relationships that determine individuals' priority of access to food and other resources. The influence of female social rank on several measures of reproductive success was examined in a population of free-living Crocuta in Kenya. The study population was continuously observed for seven years, making it possible to document litter sizes, interbirth intervals, ages of cubs at weaning, intervals between weaning one litter and conceiving the next, annual rates of production of cubs, and survival of offspring to reproductive maturity. The relationship between availability of food, social rank, and female fertility was examined by monitoring abundance of prey throughout the study period. Most measures of reproductive performance were strongly influenced by social rank. High-ranking females began breeding a younger ages, were more frequently able to support pregnancy and lactation concurrently experienced shorter intervals between litters, and produced more surviving offspring than did lower-ranking females. Low-ranking females exhibited better reproductive performance when prey animals were abundant than when prey were relatively scarce. By contrast, reproductive performance among high-ranking females was always superior to that exhibited by low-ranking females, and did not vary with prey abundance. Fertility among high-ranking females thus appeared to be less vulnerable to fluctuations in the food supply than was that among low-ranking females.

Characterization of sensorimotor performance, reproductive and aggressive behaviors in segmental trisomic 16 (Ts65Dn) mice

In the present study, segmental trisomy 16 (Ts65Dn) mice, an animal model of Down Syndrome (DS), were examined for sensorimotor, reproductive, and aggression abnormalities associated with DS. The Ts65Dn mice exhibited no sensorimotor deficits in olfactory sensitivity, visual abilities, orientation reactions, forelimb strength, postural skills, balance/coordination, climbing, or locomotion compared to genetically matched control B6EiC3HF1 mice. In mating tests, the percentage of Ts65Dn mice displaying intromissions when paired with estrous females was significantly less than that in controls. Although the percentage of Ts65Dn mice that mounted and ejaculated with an estrous female was marginally less than in controls, there were no significant differences on the other measures of reproductive behavioral performance. In aggression tests, Ts65Dn males showed increased offensive aggression in a neutral arena both when paird and among group males, Conversely, Ts65Dn mice exhibited less offensive aggression against an intruder in their home cage than control males. In sum, these mice possess some of the adaptive behavior abnormalities observed in DS patients; however, because the Ts65Dn mice do not have any observed sensorimotor deficits that could interfere with behavioral assessments, they may serve as a useful model for the study of behavioral impairments associated with DS.

Effect of Spirulina maxima consumption on reproduction and peri- and postnatal development in rats

Spirulina maxima, an edible micro-organism useful in human nutrition, was examined for its effect on general reproductive performance and for peri- and postnatal toxicity in rats at levels of 0, 10, 20 and 30% (w/w) incorporated into the diet. There was no reduction in body weight gain of males or females and no deaths or clinical signs of toxicity. Treatment was not associated with any adverse effect on any measure of reproductive performance, including male and female fertility and duration of gestation. There was no increase in the number of abnormal pups at caesarean section or at birth. S. maxima consumption did not result in adverse effects on developmental markers of the pups.

Riboflavin nutrition of sows.

Two experiments were conducted to evaluate the response of sows to high levels of dietary riboflavin. Responses evaluated were erythrocyte glutathione reductase activity coefficient (EGRAC, a biochemical indicator of riboflavin status) and reproductive performance. In Exp. 1, eight sows were fed diets either slightly deficient or superadequate in riboflavin throughout a reproductive cycle, beginning in midgestation. The EGRAC values confirmed the slight deficiency (P < .01) but did not clearly show a time when the sow is most likely to be deficient in riboflavin. In Exp. 2, 118 sows at two farms were fed diets providing 10 (control, 1.4 times the NRC [1988] requirement estimate), 60, 110, or 160 mg of riboflavin/d for 21 d beginning at breeding, and the control level through the remainder of the reproductive cycle. The percentage of sows farrowing tended to be lower (P < .10) for the control sows than for sows fed the other treatments (66.7, 85.7, 93.3, and 86.7% for 10, 60, 110, and 160 mg/d, respectively). This response is similar to other results reported previously. No other measure of reproductive performance nor EGRAC measured at any of five stages of the reproductive cycle, was affected by treatment. These results suggest that massive riboflavin supplementation of the sows' diet during early pregnancy may increase the percentage of farrowing but does no increase litter size.

Limited Effects of Ozone Exposure during Pregnancy on Physical and Neurobehavioral Development of CD-1 Mice

Only a few studies have attempted to assess in laboratory rodents the maternal toxicity and behavioral changes in offspring caused by prenatal exposure to ozone (O3). In particular, no data are available concerning the behavioral development of mouse offspring after maternal exposure, despite the fact that increasing use is made of this species in behavioral teratology studies for reasons both of economy and in order to increase the effectiveness of subsequent higher-tier studies (e.g., of treatment-genotype interactions). In the present work, female CD-1 mice were exposed during pregnancy (Days 7-17) to different O3 concentrations (0, 0.4, 0.8, or 1.2 ppm); to avoid confounding by postnatal maternal effects, all litters were assigned shortly after birth to foster dams neither treated nor handled during pregnancy. The dams′ food and water intake and body weight gain were depressed in a concentration-dependent fashion. Tolerance to these effects developed during continuing exposure; such tolerance was faster in the case of food than water intake. Several measures of reproductive performance, such as proportion of pregnancies carried to term, litter size, sex ratio, frequency of stillbirth, and neonatal mortality, failed to show differences between control and O3 animals. Postnatal body weight gain was slightly but significantly depressed in the 1.2 ppm offspring. Otherwise, the somatic development of O3 pups was indistinguishable from that of controls, save for a delay in eye opening; this effect, however, failed to show a significant concentration dependence. Negative results were obtained in a wide range of assessments concerning (i) the development of various reflexes and responses ("Fox battery") from birth to Day 18; (ii) ultrasonic emissions on Postnatal Days 3, 7, and 11; and (iii) activity, habituation, response to an unfamiliar object, and hyperactivity produced by a monoaminergic stimulant (d-amphetamine) at 60-61 days. The present data differ from those of a previous study on rats raised by their biological mothers after gestational exposure to O3 (1 and 1.5 ppm), which showed a substantial impairment in somatic and neurobehavioral development (R. Kavlock, E. Meyer, and C. T. Grabowski, 1980, Toxicol. Lett.5, 3-9). This difference, be it due to species factors, to postnatal maternal effects, or to the time of occurrence of maximal O3 effects (e.g., on food and water intake) after the onset of exposure and before adaptation or tolerance, may provide significant cues for the understanding of O-3 effects in pregnant and developing organisms.

Assessment of the Reproductive and Developmental Toxicity of Pesticide/Fertilizer Mixtures Based on Confirmed Pesticide Contamination in California and Iowa Groundwater

Assessment of the Reproductive and Developmental Toxicity of Pesticide/Fertilizer Mixtures Based on Confirmed Pesticide Contamination in California and Iowa Groundwater. Heindel, J. J., Chapin, R. E., Gulati, D. K., George, J. D., Price, C. J., Marr, M. C., Myers, C. B., Barnes, L. H., Fail, P. A., Grizzle, T. B., Schwetz, B. A., and Yang, R. S. H. (1994). Fundam. Appl. Toxicol. 22, 605-621.Pesticides and fertilizers, as used in modern agriculture, contribute to the overall low-level contamination of groundwater sources. In order to determine the potential of pesticide and fertilizer mixtures to produce reproductive or developmental toxicity at concentrations up to 100X the median level found in groundwater, we prepared and studied two mixtures of pesticides and a fertilizer (ammonium nitrate). One mixture containing aldicarb, atrazine, dibromochloropropane, 1,2-dichloropropane, ethylene dibromide, and simazine plus ammonium nitrate was considered to be a representative of groundwater contamination in California (CAL). The other, containing alachlor, atrazine, cyanazine, metolachlor, metribuzin, and ammonium nitrate, simulated groundwater contamination in Iowa (IOWA). Each mixture was administered in the drinking water of either Swiss CD-1 mice during a Reproductive Assessment by Continuous Breeding study or pregnant Sprague-Dawley rats (gd 6-20) at three dose levels (1×, 10×, and 100×) where 1× was the median concentration of each pesticide component as determined in the groundwater surveys in California or Iowa. Unlike conventional toxicology studies, the purpose of this study was to evaluate the health effects of realistic human concentrations. Thus, the testing concentrations are probably well below the maximally tolerated dose. Propylene glycol was used as the solubilizer for the pesticides in drinking water formulations in both studies. In the reproductive study, neither mixture caused any clinical signs of toxicity, changes in food or water consumption, or body weight in either F0 or F1 mice at doses up to 100× the median groundwater concentrations. There were no treatment-related effects on fertility or any measures of reproductive performance of either the F0 or the F1 generation mice exposed to either CAL or IOWA at up to 100×. Similarly, measures of spermatogenesis, epididymal sperm concentration, percentage motile sperm, percentage abnormal sperm, and testicular and epididymal histology were normal. In the developmental study, CAL- or IOWA-exposed females did not exhibit any significant treatment-related clinical signs of toxicity. No adverse effects of CAL or IOWA were observed for measures of embryo/fetal toxicity, including resorptions per litter, live litter size, or fetal body weight. CAL or IOWA did not cause an increased incidence of fetal malformations or variations. In summary, administration of these pesticide/fertilizer mixtures at levels up to 100-fold greater than the median concentrations in groundwater supplies in California or Iowa did not cause any detectable reproductive (mice), general, or developmental toxicity (rats).