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PubMed1995

The educational implications of reproductive problems identified during investigations at Michigan dairy farms.

This study constitutes the review of 44 dairy herd investigations that were initiated because of complaints relating to decreased reproductive efficiency. Each investigation was conducted at the request of the veterinary practitioner who provided the routine reproductive examinations and consultations at the farm. Thus the types of problems identified were those not resolved by routine veterinary care and management practices. A total of 4.5, 27.3 and 31.8% of the farms, respectively, failed to keep reproductive records, failed to maintain accurate records on events such as breeding dates, or failed to evaluate available summary reports with the local veterinary practitioner. Of the 44 farms, 50.0, 38.6, 54.5 and 11.4%, respectively, reported problems related to estrus detection rate, number of days to first service (for reasons other than estrus detection), conception rate and early embryonic death. Within each of these reproductive parameters specific problems were defined and discussed. Reproductive inefficiency was found to be most commonly associated with ineffective estrus detection and decreased conception rate. Most importantly, farm managers and employees frequently misunderstood the relationship between the accuracy of estrus detection and the conception rate (61.4% of the farms). We therefore identified factors which have an impact on dairy herd reproductive efficiency to suggest topics for training programs for producers and practicing veterinarians as well as for elective courses for veterinary students in the area of theriogenology.

Journal Article↗

PubMed2006

A two-generation reproductive toxicity study of octamethylcyclotetrasiloxane (D4) in rats exposed by whole-body vapor inhalation.

This study evaluated the potential toxicity of whole-body vapor inhalation of octamethylcyclotetrasiloxane (D(4)) on reproductive capabilities in exposed F(0) and F(1) parental animals and the potential effects on neonatal survival, growth, and development of the F(1) and F(2) offspring. F(0) male and female Sprague-Dawley rats (30/sex/group) were exposed to D(4) vapor at concentrations of 0, 70, 300, 500 or 700 ppm 6h per day for at least 70 consecutive days prior to mating and lasted through weaning of the pups on postnatal day (PND) 21. Female exposures were suspended from gestation day (GD) 21 through PND 4 to allow for parturition and permit continuous maternal care for the early neonates. Starting on PND 22, F(1) weanlings were exposed to D(4) as described for the F(0) generation. The F(2) pups were not directly exposed to D(4). F(0) animals were mated once to produce the F(1) generation; F(1) parental animals were mated twice to produce two F(2) litters. In addition, the F(1) males were mated with unexposed females. Prolonged estrous cycles, decreased mating and fertility indices were observed in the F(1) generation exposed to D(4) for the first and second matings. Significant reductions in the mean number of pups born and mean live litter size were observed in the 500 and 700 ppm groups for both the F(0) and F(1) generations. Implantation sites were also reduced at 700 ppm for both F(0) and F(1) generations. No adverse effects were observed at any exposure level on anogenital distance, vaginal patency and preputial separation. No adverse effects were seen on male functional reproductive parameters, spermatogenic endpoints, microscopic evaluation of male reproductive tissue, or when the D(4)-exposed F(1) males were mated with the unexposed females, demonstrating that the reproductive toxicity observed was due to D(4) exposure to the females. Based on the lack of effect on reproduction when the D(4)-exposed males were mated to näive females, the NOAEL for male reproductive toxicity was considered to be 700 ppm. Based on the statistically significant effects on fertility and litter size, NOAEL for female reproductive toxicity was considered to be 300 ppm. The findings observed in this study are consistent with suppression or delaying of LH surge as well as acceleration of the onset of female reproductive senescence in the rat. While analogous pathways control ovulation in both rats and humans, there are significant differences in the mechanism for timing and release of LH and resulting changes in the control of ovulation and mating behavior between the two species. If D(4) delays rather than causes a prolonged suppression or ablation of the LH surge, the reproductive mode of action of D(4) would not likely be relevant for humans.

Adjuvants, Immunologic↗

PubMed2000

Absence of structural or functional alterations in male and female reproductive organs of F1 and F2 generations derived from female mice exposed to 3'-azido-3'-deoxythymidine during pregnancy.

To investigate the effects of in utero exposure to 3'-azido-3'-deoxythymidine (AZT) on male and female reproductive system development, pregnant CD-1 mice were given daily intragastric doses of 25.0 mg AZT during days 12 through 18 of gestation. The offspring were examined at birth, as well as at pubertal, young adult and adult stages of development, for reproductive organ endpoints including anogenital distance, onset of testicular descent, latency to vaginal opening, and proportion of time for each of the stages of estrous cycle. These reproductive endpoints remained mostly unchanged in AZT-treated offspring as compared to the controls. Males and females exposed in utero to AZT (F1 generation) were fertile when mated to untreated females and males, respectively, and their liveborn F2 offspring showed no adverse effects for any of the reproductive parameters tested. Thus, no evidence of developmental reproductive toxicity was noted either in the F1 mice exposed to AZT during the critical period of male and female reproductive system development, or in the F2 mice born of matings between the AZT-exposed F1 mice and unexposed animals.

Abnormalities, Drug-Induced↗

PubMed1999

Evaluation of apomorphine HCl effects on reproductive endpoints: studies in male rats and dogs.

Apomorphine HCl is currently in phase III clinical trials for the treatment of erectile dysfunction. The potential for reproductive toxicity in males was assessed based on a 13-week rat study--a fertility study in male rats--and a 6-month study in dogs. The subcutaneous (s.c.) route was selected to simulate the sublingual route in humans. Dosages of apomorphine were 0.0 (vehicle), 0.8, 2, and 8 mg/kg/day in the 13-week study in rats (20/group), with 8 mg/kg/day used for only 9 weeks. In the fertility study, 24 males/group were cohabited with females, and doses were 0.0, 0.2, 0.8, and 2 mg/kg/day. Males were treated for 4 weeks prior to cohabitation and for 5 weeks throughout cohabitation. Organ weights, including testis and left epididymis, sperm count and morphology in the epididymis, and sperm motility in the vas deferens were evaluated. Male fertility index, and in females, the numbers of fetuses, implantation sites, and corpora lutea were counted. Male dogs (five/group) were dosed with 0.04, 0.1, or 0.4 mg/kg/day for 6 months. Epididymal and prostate weight, and testicular and epididymal histology were evaluated. Daily morbidity/mortality, weekly clinical observations, body weight, and food consumption were evaluated in all studies. No adverse effect was observed in any of the reproductive parameters in the studies. The NOEL for reproductive toxicity was approximately equal to 0.4 mg/kg/day in dogs and > or = 2 mg/kg/day in rats. These doses in rats and dogs correlated with plasma levels of approximately 240 and 130 ng/mL, and AUCs of 200 and 100 ng.h/mL, respectively. These levels suggest a safety margin for the evaluated male reproductive endpoints of at least 104 times based on the Cmax, and 44 times based on AUC of the clinical dose.

Animals↗

PubMed1997

Alteration of testicular response to long photoperiod by transient exposure to short photoperiod in collared lemmings (Dicrostonyx groenlandicus).

The reproductive response of collared lemmings (Dicrostonyx groenlandicus) to photoperiod is unique for rodents. Whereas most reproductively photoresponsive rodents show maximal gonadal growth when exposed to long photoperiod (long day), collared lemmings show delayed maturation when born and maintained under this condition. However, transfer of lemmings from short photoperiod (short day) to long day results in maximal gonadal growth, indicating that the response to long day depends upon photoperiod history. We hypothesized that the slowing of maturation observed in animals born and maintained on long day reflects an inability to respond fully to long day, resulting from the absence of previous exposure to short day. To determine whether young lemmings born in long day are capable of being stimulated by long day, we exposed them at weaning (19 days of age) to 1, 6 or 10 weeks of short day, and then challenged them with a second exposure to long day. Relative to animals transferred permanently to short day at weaning, lemmings exposed to 6 weeks of short day showed accelerated gonadal growth after both 5 and 10 weeks of subsequent exposure to long day, and those exposed to 10 weeks of short day had larger testes after 6 weeks of long day. Thus, during transient exposure to short day, the animals acquired sensitivity to the stimulatory effects of long day. The responses of body mass, bifid claw width and pelage colour to the photoperiod manipulations did not parallel that of the gonads, indicating independent regulation of somatic and reproductive parameters. The unique way in which the reproductive system of collared lemmings responds to photoperiod may reflect evolution in an environment where the production of offspring during periods of unchanging long day (for example, the Arctic summer) is not selectively advantageous.

Animals↗

PubMedDate not supplied

Oral (drinking water) two-generation reproductive toxicity study of dibromoacetic acid (DBA) in rats.

In a two-generation study of dibromoacetic acid (DBA), Crl SD rats (30 rats/sex/group/generation) were provided DBA in drinking water at 0 (reverse osmosis-deionized water), 50, 250, and 650 ppm (0, 4.4 to 11.6, 22.4 to 55.6, and 52.4 to 132.0 mg/kg/day, respectively; human intake approximates 0.1 microg/kg/day [0.0001 mg/kg/day]). Observations included viability, clinical signs, water and feed consumption, body and organ weights, histopathology, and reproductive parameters (mating, fertility, abortions, premature deliveries, durations of gestation, litter sizes, sex ratios and viabilities, maternal behaviors, reproductive organ weights, sperm parameters and implantation sites, sexual maturation). Histopathological evaluations were performed on at least 10 P and F1 rats/sex at 0 and 650 ppm (gross lesions, testes, intact epididymis; 10 F1 dams at 0, 250, and 650 ppm for primordial follicles). Developmental observations included implantations, pup numbers, sexes, viabilities, body weights, morphology, and reproductive performance. At 50 ppm and higher, both sexes and generations had increased absolute and relative liver and kidneys weights, and female rats in both generations had reduced absolute and relative adrenal weights; adrenal changes were probably associated with physiological changes in water balance. The livers and kidneys (10/sex/group/generation) had no histopathological changes. Other minimal effects at 50 ppm were reduced water consumption and a transient reduction in body weight. At 250 and 650 ppm, DBA reduced parental water consumption, body weight gains, body weights, feed consumption, and pup body weights. P and F1 generation male rats at 250 and 650 ppm had altered sperm production (retained step 19 spermatids in stages IX and X tubules sometimes associated with residual bodies) and some epididymal tubule changes (increased amounts of exfoliated spermatogenic cells/residual bodies in epididymal tubules, atrophy, and hypospermia), although inconsistently and at much lower incidences. Unilateral abnormalities of the epididymis (small or absent epididymis) at 650 ppm in four F1 generation male rats were considered reproductive tract malformations. The no-observable-adverse-effect level (NOAEL) and reproductive and developmental NOAELs for DBA were at least 50 ppm (4.5 to 11.6 mg/kg/day), 45,000 to 116,000 times the human adult exposure level. Reproductive and developmental effects did not occur in female rats exposed to DBA concentrations as high as 650 ppm. Based on the high multiples of human exposure required to produce effects in male rats, DBA should not be identified as a human reproductive or developmental risk.

Acetates↗

PubMed2005

Demography, range use, and behavior in black lemurs (Eulemur macaco macaco) at Ampasikely, northwest Madagascar.

We studied a black lemur population over a 2-year period (1992-1993) and 8 years later (2000) in a 50-ha secondary forest in northwest Madagascar. All of the animals were marked to investigate population dynamics and seasonal variation in ranging and behavior, and new data on black lemurs were obtained. Our data on demographic characteristics were expanded to include other forest sites and contrasted with those collected in other Eulemur macaco macaco field studies, in relation to human activity and the presence of introduced and cultivated plant species. Density is affected by deforestation and hunting. Group size and home range depend on the composition of the forest and probably food patches. Sex ratio at birth varies according to the number of females per group, a result that fits the local resource competition model. Groups are multimale-multifemale, and adult females form the core of the groups. Reproductive parameters indicate sharply defined seasonal breeding, a high female reproductive rate, and birth synchrony. Changes in group composition reveal male and female juvenile dispersal, male transfer between groups at the time of mating, and adult female transfer and group fission when groups exceed a critical size. At mating and birth, intergroup agonistic encounters occurred at home-range boundaries, and larger groups were dominant over smaller groups. Patterns of intragroup interactions suggest that males compete for access to groups of females during the mating season, and that females may compete for food resources during the birth season. Our study also reports female social dominance and lack of sexual weight dimorphism in this species.

Animals↗

PubMed1989

Effects of elevated foodborne selenium on growth and reproduction of the fathead minnow (Pimephales promelas).

Several field studies of selenium-contaminated lakes and reservoirs have indicated the possibility of selenium-induced reproductive failure in important populations of fish. These investigators have hypothesized that bioaccumulation of selenium through the food chain led to fish selenium levels high enough to elicit toxic responses. The present investigation was designed to determine the effects of elevated foodborne selenium on the fathead minnow (Pimephales promelas). Fish were fed a diet spiked with a mixture of inorganic (selenite and selenate) and organic (seleno-L-methionine) selenium and effects on growth and reproduction were determined. Growth was significantly inhibited at the highest selenium treatment levels evaluated (20 and 30 ppm Se). There were no significant treatment effects on any of the reproductive parameters measured. Reasons for the disparity between selenium-induced reproductive impairment observed in other species and apparent lack of impairment in fathead minnows may involve reduced bioaccumulation of selenium by minnows due to differences in gut morphology and physiology.

Animal Feed↗

PubMed2005

[Efficiency of a herd health program in Swiss dairy herds].

A retrospective analysis of the reproductive parameters was conducted in 15 dairy farms using a herd health monitoring system between 1995 and 1998. Five of these farms have used this monitoring process for many years (group 1) while 10 of them only initiated the process in 1996 (group 2). It was the aim of this study to evaluate the economic gain of the farms in each group due to the herd health monitoring program throughout the three year study period, by using Value Based Management (VBM), a model from the economic sciences. The mean calving to conception interval decreased from 93.3 to 84.0 days and from 104.9 to 86.7 days throughout the study period in groups 1 (P>0.05) and 2 (P < 0.05), respectively. The mean percentage of cows with calving to conception intervals below 115 days varied between 68.2% and 82.0% in group 1, while there was an increase form 65.2% to 78.6% in group 2 (P<0.05). There were no apparent trends in the reproductive culling rate throughout the study period (P>0.05), and the majority fell below 10%. Likewise, the first service conception rate varied between 52.7% and 56.6% and between 41.2% and 50.0%, in group 1 and 2, respectively. The number of services per conception varied between 1.6 and 1.8 and between 1.8 and 1.9, in groups 1 and 2, respectively. The number of days between calving and first service varied between 62.7 and 64.8 days in group 1, while it decreased significantly from 69.2 to 59.2 in group 2 (P<0.05). The time between first service and conception decreased from 30.6 to 22.0 days, and from 35.7 to 28.0 days in groups 1 and 2, respectively (P<0.05). Although there was an apparent increase of the detection rate of oestrus from 57.8% to 68.2% throughout the study period in group 1, it was not significant (P > 0.05). In group 2, however, the oestrus detection rate increased significantly from 53.0% to 69.9% (P < 0.05). The percent of detected oestrus within 42 days post partum increased from 33.1% to 38.1%, and from 24.1% to 40.9% in groups 1 and 2, respectively (P < 0.05). By 1998, four out of five farms in group 1, and five out of the eight farms where information was avail- year study period of CHF 25.- to CHF 609.- per cow and year. The calving to conception interval and the reproductive culling rate were the two most important parameters to determine the reproductive performance of the herd and the economic benefit of the herd health monitoring program. These findings support the implementation of a herd health monitoring program.

Animal Welfare↗

PubMed1997

[Population parameters of three parasitoids (Hymenoptera: Scelionidae, Encyrtidae) hosted by the predator Podisus nigrispinus (Heteroptera: Pentatomidae)].

The reproductive parameters of Telenomus podisi, Trissolcus brochymenae (Hymenoptera: Scelionidae) and Ooencyrtus sp. (Hymenoptera: Encyrtidae) were studied for three generations on their natural host Podisus nigrispinus (Dallas, 1851) (Hemiptera: Pentatomidae). A parasitism rate of 10 eggs/day/species was used under laboratory conditions of 27 +/- 1 degrees C, 60 +/- 10% RH and 14 h of photophase. No significant differences were detected between generations in terms of net reproductive rate (Ro), intrinsic rate of natural increase (rm), generation time (T) and the effect of doubling time on population increase (DT). However, T. podisi and T. brochymenae had significantly higher Ro and rm values, and lower T and DT values, with rm 1.59 and 1.50 times higher than Ooencyrtus sp., respectively. In addition the former species also had shorter egg-adult period, greater longevity of females and reproduction period than the other species. These results confirm the greater reproductive potential of T. podisi and T. brochymenae, which are commonly found parasitizing P. nigrispinus.

Animals↗

PubMed1999

Recombinant bovine somatotropin: association with reproductive performance in dairy cows.

A clinical trial was performed to determine the effect of bST on reproductive performance in dairy cows on 4 Michigan dairy farms when bST was used according to labeled directions. Holstein cows (n = 555) at 4 Michigan dairy farms were randomly assigned to receive bovine somatotropin (bST) or to serve as untreated controls. Bovine somatotropin (500 mg, s.c.) was administered every 14 d beginning at 63 to 69 d of lactation and continuing until approximately 21 d prior to the end of lactation or until the producer removed the animal from the herd. A total of 229 (42.57%) animals consisting of 112 (48.91%) controls and 117 (51.09%) bST-treated cows were not diagnosed pregnant and were considered as having reproductive failure by 150 d of lactation and 92 (17.10%) of the animals consisting of 45 (48.91%) controls and 47 (51.09%) bST-treated cows had reproductive failure at the end of their lactation. No significant difference in the incidence of reproductive failure existed between the study treatment groups during either time frame. Cows with cystic ovarian disease had more instances of reproductive failure at 150 d of lactation than cows without this disease. Cows with dystocia, twin births, metritis, displaced abomasum and cystic ovarian disease had more instances of reproductive failure by the end of lactation than cows without these diseases. The bST-treated cows developed more nonspecific off feed conditions during the study lactation and had more twin births at the calving following bST administration compared to control cows. No differences were found between the study treatment groups in calculations of reproductive parameters. Logistic regression analysis found no significant effect of bST on reproductive failure; the odds ratios for the bST treatment effect on reproductive failure at 150 d of lactation and reproductive failure at the end of lactation were 0.95 (95% CI 0.67 to 1.36) and 0.95 (95% CI 0.59 to 1.54), respectively. Overall, bST was not found to have a significant impact on reproductive performance in the herds studied.

Abortion, Veterinary↗

PubMed1986

Reproduction in the vervet monkey (Cercopithecus aethiops): endometrial oestrogen and progestin receptor dynamics during normal and prolonged menstrual cycles.

Sixteen individually caged adult female vervet monkeys (Cercopithecus aethiops), whose reproductive parameters had been studied for 5 years, were hysterectomized/ovariectomized during three reproductive states; i.e. the late follicular (15.4 +/- 4.7 (S.D.) days) and luteal (27.8 +/- 4.7 days) phases of the normal cycle (20-50 days), and during prolonged intermenstrual intervals (PII; 99.0 +/- 2.5 days since the previous menses). These latter animals showed characteristics of both follicular and luteal phases; i.e. their ovaries contained both corpora lutea and large antral follicles and systemic oestradiol and progesterone concentrations were raised. Analysis of cytoplasmic oestrogen and progestin receptors (CER and CPR) revealed that endometrium during PII had CER levels of 0.58 +/- 0.07 pmol/mg protein, similar to those of the follicular phase (0.60 +/- 0.12); CPR levels (1.20 +/- 0.87) were not different from those of the luteal phase (1.05 +/- 0.45). The ratio of CPR to CER during the luteal phase was about tenfold higher than that of the follicular phase. Levels during PII were intermediate between the two phases. Under receptor-activating conditions, the DNA-binding components of the PII cytoplasmic fraction underwent over 40% loss while those present during both phases of the normal cycle doubled. The hormone-binding sites at all times remained intact indicating that the DNA and hormone-binding sites are distinct on both CER and CPR. Less than 50% interaction of CER/CPR with DNA-cellulose was obtained, indicating the presence of only limited quantities of cytoplasmic activating factors which may be a prerequisite for receptor binding to the genome. During PII, factors which deactivate DNA-binding sites may also have been induced. Extensive accumulation of nuclear oestrogen receptor was evident in PII endometrium with 80% being salt-resistant. This level is higher than that in the follicular and luteal phases (37 and 52% respectively). These data, suggesting a possible aberration of receptor activation in vitro and receptor processing in vivo, may be indicative of endometrial dysfunction during PII. This could lead to a delay in menstruation.

Animals↗

PubMed1996

Infection with Trypanosoma brucei potentiates the antifertility effect of gossypol, especially in the protein-malnourished male rat.

Reproductive parameters were investigated in gossypol-treated male rats that had been infected experimentally with Trypanosoma brucei and then place on one of two diets of differing (low and normal) protein content. The endpoints assessed were reproductive organ weights, semen epididymal sperm counts, serum testosterone and histological, stereological and histomorphometric evaluation of the testis and accessory reproductive organs. Most of the parameters studied were lowest in the protein-malnourished, gossypol-treated, trypanosome-infected animals, when compared to those obtained from the corresponding animals that were only gossypol-treated or trypanosome-infected. Mean testicular size and the diameter and the total length of seminiferous tubules were especially reduced, indicating that the overall volume of the seminiferous epithelium in these animals was smaller. These findings suggest that reproductive capacity could be impaired in protein-malnourished, trypanosome-infected animals fed on gossypol-containing products, even when there are no obvious clinical signs of disease. This could translate into increased production costs in a farm enterprise. Screening for haemoparasitism would also seem to be worthwhile prior to evaluation and/or use of gossypol (or perhaps other potential contraceptives) in human subjects, especially in communities that are confronted with severe food shortages.

Animals↗

PubMedDate not supplied

[The effect of feeding frequency on some population parameters of Rhodnius neivai].

After changing feeding frequency to a weekly and biweekly basis, a statistical evaluation of the variation of some population and reproductive parameters was conducted. It was based on four cohorts experiments of Rhodnius neivai fed on hen or rabbit. We found a direct relationship between blood feeding frequency and the parameters adult average longevity, maximum longevity and life expectancy in the animals fed on hen. On the other hand, in the insect fed biweekly on rabbit, these three values were higher than the registered in the cohorts fed weekly. Reproductive output got bigger and age-specific fertility showed a small decrease when feeding frequency was weekly. Every population parameter, except generation time, was greater in the individuals fed weekly.

Animals↗

PubMed1993

Multigeneration studies on red palm oil, and on hydrogenated vegetable oil containing mahua oil.

Edible grade red palm oil (RPO; Elaeis guineensis) is being considered for use an an edible oil in India since it is one of the richest natural sources of carotenoids. Earlier chemical and nutritional evaluations in rats indicated no adverse effects. Multigeneration breeding studies in rats have now been carried out. Mahua oil (MO; Madhuca latifolia) is used in hydrogenated vegetable oil (HVO) for human consumption. Earlier studies on MO indicated adverse effects on the male reproductive system. Hence, a study was undertaken to evaluate the safety of HVO containing 30% MO (MO-HVO) in terms of reproductive performance. A three-generation study was conducted with groups of 12 male and 12 female Wistar/NIN/inbred albino rats fed, at 10% in the diet (20% protein), groundnut oil (controls), RPO, refined, bleached and deodorized palmolein (RBDPO), or MO-HVO. Reproductive parameters including percentage conception, birth weight, litter size, weanling weight, sex ratio at birth and weaning, preweaning mortality and number of days from introduction to mating, were recorded. Behavioural and reflexological tests were conducted on preweaning animals. Adult animals were subjected to weekly observation. No significant differences were found between the RPO and MO-HVO groups in comparison with groups fed GNO or RBDPO in any of the above parameters. However, certain indications of reduced fertility were observed in the MO-HVO group in the first and third generations. The results indicate that RPO did not produce any adverse effect on reproductive performance or other toxicological parameters studied, and therefore it can be considered as safe for consumption. On the other hand, HVO containing 30% MO needs further testing with a larger number of animals.

Administration, Oral↗

PubMed2005

Susceptibility of reproduction in female pigs to impairment by stress or elevation of cortisol.

It is generally agreed that stress can impair reproduction. Furthermore, it is often thought that cortisol, which is secreted during stress as a result of activation of the hypothalamo-pituitary adrenal axis, is associated with this stress-induced impairment of reproduction. It has been hypothesized that reproduction in females is particularly susceptible to disruption by acute stress during the series of endocrine events that induce estrus and ovulation. Nevertheless, we found no support for this conjecture when we subjected female pigs to repeated acute stress or repeated acute elevation of cortisol during the period leading up to estrus and ovulation. Conversely, studies have demonstrated that prolonged stress and sustained elevation of cortisol can disrupt reproductive processes in female pigs. Nevertheless, in each study that demonstrated this effect, there were some animals subjected to the prolonged stressor or the sustained elevation of cortisol in which the reproductive parameters that were measured were not affected by the treatment. We propose that reproduction in female pigs is resistant to the effects of acute or repeated acute stress or acute or repeated acute elevation of cortisol even if these occur during the series of endocrine events that induce estrus and ovulation. Furthermore, while reproductive processes in some individuals are compromised, reproduction in a proportion of female pigs appears to be resistant to the effects of prolonged stress or sustained elevation of cortisol.

Animals↗

PubMed1999

Reproductive performance of farmed red deer (Cervus elaphus) in New Zealand. I. Descriptive data.

A longitudinal observational study of 15 red deer (Cervus elaphus) farms was carried out in New Zealand for 2 years from Mar 1992. Management of hind mobs and their composition during mating, calving, and weaning were recorded. About 2700 hinds were individually monitored for live weight, body condition score and reproductive success. All hinds were pregnancy tested in June by ultrasound and classified as having conceived before May 1, after May 1, or as being not pregnant. Calving dates and dam-offspring pairs were recorded on four farms. The lactational status of hinds and live weight of calves were recorded at weaning. Mean pre-mating live weights of yearling hinds were 81.3-82.8 kg and of adult hinds 98.0-98.7 kg, respectively, for each year of study. The percentage of yearling and adult hinds conceiving before May ranged from 8.3 to 95.0% and from 77.6 to 98.4%, respectively, between farms. Overall, the proportion of yearling and adult hinds not pregnant was 15.3% and 3.2%, respectively. Pregnancy rates at scanning of adult hinds within mating mobs were generally over 90%, and 41.7% of mating mobs had 100% pregnancy rates. In contrast, the pregnancy rates of yearling hind mobs were more variable, with five mobs below 50%, and 34.1% of mating mobs achieving 100% pregnancy rate. Estimated in utero loss rates from pregnancy diagnosis to calving were 0.66 and 0.79% for yearling and adult hinds, respectively. From four farms, median calving dates of yearling and adult hinds were Dec 13 and Nov 30, respectively. Overall, calf survival rates to weaning of yearling and adult offspring were 84.1 and 91.6%, respectively, while the reproductive efficiencies (number of calves weaned per hind mated) were 70 and 83.6%, respectively. Farm mean weaner live weights standardised on Apr 1 ranged from 42-59 kg and 39-51 kg for stags and hinds, respectively. These data are currently the best estimates of reproductive parameters of New Zealand red deer herds, and highlight a wide variability in reproductive indices between farms.

Animal Husbandry↗

PubMed1976

A study of certain environmental factors and mineral chelation on the reproductive performance of young and yearling turkey hens.

The study presented was designed to determine the effects of laying cages and conventional litter floors, pen temperatures of 12.8 degrees, 21.1 degrees and 29.4 degrees C., and chelated (EDTA-Zn) vs. nonchelated trace mineral mixes on the reproductive performance of yearling force-molted and young Large White female turkeys. Reproductive performance, as measured by egg production, settable eggs, fertility and hatchability of fertile eggs, was not significantly different between young and yearling hens. Females fed a chelated trace mineral mix had a higher percentage of settable eggs, greater feed consumption and thicker egg shells. Females in laying cages laid at a higher rate, ate more feed, and weighed more than those on conventional floors. Significant differences were not observed between the two pen environments for hatchability of fertile eggs or egg weight. The percentages of settable eggs and of fertile eggs were lower when females were maintained in cages. A constant temperature of 29.4 degrees C. reduced egg production below that obtained from females maintained at 12.8 degrees and 21.1 degrees C. The high pen temperature also caused lower body and egg weights, more birds out of production and an increased incidence of molting. Feed consumption decreased with increasing pen temperatures. Fertility, hatchability, percentage of settable eggs and egg shell thickness were unaffected by the imposed temperature environments. Temperatures of 12.8 degrees and 21.1 degrees C. yielded comparable results for all reproductive parameters measured. Within the range of temperatures studied, results obtained suggest that optimum reproductive performance can be obtained with breeder turkeys when environmental temperatures are maintained between 12.8 degrees and 21.1 degrees C.

Animal Feed↗