Fetal Litter Size Research Articles

Factors influencing pregnancy, litter size, and reproductive parameters of invasive wild pigs

AbstractReproduction is the most energetically expensive life stage with the demands of productivity representing a balance between physiological requirements and environmental conditions. Wild pigs (Sus scrofa) throughout most of North America are genetic hybrids of feral domestic pigs and wild boar and have the highest reproductive potential of any wild ungulate. The phenology of reproduction, extent of multiple reproductive events per year, how individual and extrinsic factors contribute to variability in productivity, and impact of genetic lineage on these parameters is not well understood in wild pigs. We quantified reproductive parameters in wild pigs relative to a suite of individual and environmental attributes across seasons and multiple years in South Carolina, USA, from March 2017 and May 2020. We hypothesized that individual attributes (mass, age class, number of teats, rump fat, relative genetic association to wild boar vs. domestic pigs) and extrinsic factors (mast availability) would influence probability of pregnancy and fetal litter size. Wild pigs produced offspring throughout all months with peaks in conception corresponding to a seasonal pulse in food availability. The likelihood of pregnancy was influenced by female mass and nutritional condition and was greatest during years with abundant resources. Similarly, litter size increased with female mass and age, implying larger and older females represent the most important group for population recruitment. In evaluating the relationship between reproductive output and ancestral associations to domestic pigs versus wild boar, the proportion of wild boar ancestry was not an important influence on productivity in our population. We determined juveniles reach a physiological threshold of sexual maturity at approximately 30 kg. Average litter size was comparable to other populations, and wild pigs maintain an average fetal litter size of 5.43 offspring despite 13.6% embryonic mortality. A thorough understanding of biotic and extrinsic factors influencing reproduction are important for realistic population models, which are necessary for identifying areas to focus management needs and implementation.

English

The study's main objective was to assess any pathophysiological significance of Acacia nilotica pods aqueous extract and Albizia lebbeck stem bark methanolic extract on the reproductive system of female multimammate rats (Mastomys natalensis). A total of 60 sexually mature female rats were randomized into a 2 × 3 factorial experimental design for treatments (Control, A. nilotica, and A. lebbeck) and treatment duration (7 or 14 days). Control rats consumed basal feed only, whereas extract-treated rats consumed the basal feed containing 2% w/w of either of the two plant extracts. At the end of treatment duration, treated female rats were cohabited with males for 16 days and sacrificed 20 days after the first day of cohabitation. Parameters including pregnancy rates, number of fetal implantations, possible resorption sites and fetal litter size were assessed at necropsy. Further post-necropsy parameters were evaluated in ovaries including the ovarian weights, follicular and corpora lutea numbers and general histopathology. Results showed that pregnancy percentages, the number of fetal implantations and fetal litter size were significantly reduced (P < 0.01) in rats under the A. nilotica and A. lebbeck extract treatments relative to the control rats. The ovarian weights of rats receiving the extracts did not differ significantly from their control counterparts (P > 0.05). However, the number of corpora lutea of pregnancy was significantly reduced (P < 0.001) in ovaries of rats under extract treatments than in their control counterparts. Instead, ovaries of rats receiving the two extracts contained a larger number of degenerating follicles, signifying halted ovulatory and conception activities. The current study has demonstrated that dietary inclusion of crude extracts from A. nilotica pods and A. lebbeck stem bark can lead to decreased fertility success rates in M. natalensis female rats through suppression of ovulatory activities and induction of follicular atresia. Key words: Rodent pests, medicinal plants, fertility success, reproductive system.

Sanitary Waste Landfill Effects on an Invasive Wild Pig Population

ABSTRACTBeing opportunistic omnivores, wild pigs (Sus scrofa) readily feed on edible garbage. Given the presence of substantial volumes of edible food waste, large multi‐county and regional municipal sanitary waste landfills constitute attractive forage resources for pigs, providing a year‐round anthropogenic source of potentially high‐quality forage. Our objective was to assess the effects that a large regional landfill has on the local pigs foraging in that facility's waste disposal cells. The landfill, located on the United States Department of Energy's Savannah River Site (SRS) in South Carolina, USA, became operational in 1998 and pigs began foraging there in 2001. By 2009 >100 pigs/night were observed foraging in the landfill, suggesting landfill establishment may have important consequences for population dynamics, public safety, and disease transmission. We evaluated changes in body mass, fetal litter size, numbers of pigs removed, and wild pig‐vehicle collisions (WPVCs) before (1980–2000) and after (2001–2019) pigs began foraging in the landfill on SRS. Body mass during the after period increased to a greater extent for pigs in the vicinity of the landfill compared to pigs on the rest of SRS. Fetal litter size increased for pigs in the vicinity of the landfill, whereas it remained unchanged on the rest of SRS. Our density surrogate (number of pigs harvested) increased around the landfill during the after period by 2.9 times, whereas on the rest of the site it only increased by 53%. No WPVCs occurred adjacent to the landfill before 2001, but WPVCs increased along the 2 major roads bordering the landfill after 2001. Effects of sanitary waste landfills on wild pig populations scavenging there can present unique challenges to population management, control, public safety, and disease transmission. Potential approaches to address these challenges could be exclusion fencing to prevent access to the landfill's waste disposal cells or enhanced placement of waste cell covers to reduce access. © 2021 The Wildlife Society.

Wild pig (Sus scrofa) reproduction and diet in the Rolling Plains of Texas

Abstract Wild pigs (Sus scrofa) are an invasive species that can negatively impact arid environments. Their invasiveness mainly stems from two aspects of their behavior: diet and reproductive ability. We examined the stomach contents (n = 89) and reproductive tracts (n = 78) taken from wild pigs from June 1996 to October 1998 in the Rolling Plains of Texas. Pigs showed variation in forage categories among seasons. Agricultural crops were used with high frequency in all seasons. Farrowing peaked between December and February, with an average fetal litter size of 4.75 ± 2.67. Older and larger sows tended to have larger litters, but sows as young as 8 months of age were reproductive. We recommend limiting pig access to agricultural crops when possible and trapping when pigs are most nutrient stressed (summer). Control efforts should be most effective immediately preceding the farrowing peak and focused on females >8 months of age.

SUSTAINED ENERGY INTAKE DEBATE GETS MORE COMPLEX

As the saying goes, you can't get something for nothing, and nowhere is this clearer than in our own bodies. Everything that we do, from breathing to walking to even sleeping, requires energy, which we gain from the food that we eat. In this modern age where food, and thus energy, is available 24/7

Limits to sustained energy intake. XVII. Lactation performance in MF1 mice is not programmed by fetal number during pregnancy

Several studies have suggested that lactation performance may be programmed by the number of fetuses during pregnancy, whereas other studies indicate that processes during lactation are more important. As gestation litter size and litter size in lactation are usually strongly correlated, separating the roles of pregnancy and lactation in lactation performance is difficult. To break this link, we experimentally manipulated litter size of MF1 mice to five or 16 pups per litter by cross-fostering. Litter size and mass at birth were recorded on day 1 of lactation prior to litter size manipulation. Maternal body mass and food intake, litter size and litter mass were measured daily throughout. After weaning, the potential differential utilisation of body tissues of the mothers was investigated. Relationships between maternal mass and food intake, including asymptotic daily food intake at peak lactation, offspring traits and other maternal parameters suggested that the number of fetuses the females had carried during pregnancy had no effect on lactation performance. Litter mass increases depended only on maternal food intake, which was highly variable between individuals, but was independent of fetal litter size. The sizes of key organs and tissues like the liver and alimentary tract were not related to maximal food intake at peak lactation or to fetal litter size, but the masses of the pelage, mammary glands and retroperitoneal fat pad were. These data suggest that while growth of the mammary glands and associated structures may be initiated in gestation, and vary in relation to the number of placentas, the ultimate sizes and activities of the tissues depends primarily on factors during lactation.

Pregnancy in aged rats that were born small: cardiorenal and metabolic adaptations and second‐generation fetal growth

Uteroplacental insufficiency is associated with adult cardiorenal and metabolic diseases, particularly in males. Pregnancy is the greatest physiological challenge facing women, and those born small are at increased risk of gestational hypertension and diabetes and delivering smaller babies. Increased maternal age is associated with exacerbated pregnancy complications. We hypothesized that pregnancy in aged, growth-restricted females unmasks an underlying predisposition to cardiorenal and metabolic dysfunction and compromises fetal growth. Uteroplacental insufficiency was induced by bilateral uterine vessel ligation (restricted group) or sham surgery (control group) on d 18 of gestation in Wistar Kyoto rats. At 12 mo, growth-restricted F1 female offspring were mated with a normal male. F1 restricted females had elevated systolic blood pressure, before and during pregnancy (+10 mmHg) but normal renal and metabolic pregnancy adaptations. F2 fetal weight was not different between groups. In control and restricted females, advanced maternal age (12 vs. 4 mo) was associated with a reduction in the hypoglycemic response to pregnancy and reduced F2 fetal litter size and body weight. Aged rats born small exhibited mostly normal pregnancy adaptations, although they had elevated blood pressure. Advanced maternal age was associated with poorer fetal outcomes that were not exacerbated by low maternal birth weight.

Morphological and reproductive characteristics of musk shrews (Suncus murinus) collected in Bangladesh, and development of the laboratory line (BAN line) derived from them.

To establish a unique laboratory line of the musk shrew with different genetic properties from previously developed laboratory lines, 49 male and 49 female shrews were captured in the campus of Bangladesh Agricultural University from October through November in 1983 and from December in 1985 to January in 1986. The shrews collected were of various ages. They had light gray coats, with slight variations in color. Except for the 12 shrews introduced into our laboratory, the total length and body weight of the shrews ranged from 17.2 to 31.9 cm and 32.5 to 147.0 g in males, and 21.1 to 26.6 cm and 40.8 to 110.0 g in females, respectively. Pregnant females were found throughout the trapping period, and the average fetal litter size was 3.54 (11 cases). Five males and 7 females of the shrews captured in 1983 were transported to our laboratory. After more than 100 days of laboratory rearing, their total length and body weight averaged 27.6 cm and 147.3 g in males, and 24.6 cm and 81.7 g in females. Their body weight was more than double that of Japanese shrews. The shrews introduced (except for one male) produced a total of 59 offspring, which were regarded as the first generation of the laboratory line (BAN Line). Gestation period and average litter size were between 28 and 30 days (10 cases) and 3.47 (17 cases), respectively. The BAN line has consisted of about 60 individuals at each generation and has been maintained as a closed breeding colony.

Effects of Fetal Litter Size on Subsequent Lactation in Mice

Four dams and their litters were crossfostered in each of eight lines of mice to examine the relationship between the number of young born alive and 12-day weight of a litter containing two young of her own and two young from each of three other dams in her crossfostering set. Phenotypic correlations within crossfostering sets between live births and 12-day weight ranged from .09 to .15 for four lines of one population (P) and from .12 to .26 for four lines of the other population (Q). Both were associated positively with body weight of dams after parturition. Partial correlations holding this constant ranged from .04 to .08 in P and from .10 to .24 in Q. Standardized partial regressions of dam's weight after parturition on 12-day weight were larger than those of live births in both populations. Squared multiple correlations ranged from .04 to .08 in P and .02 to .10 in Q. The portion of variation of 12-day weights due to live births ranged from .6 to 1.7% in P and from 1.3 to 6.7% in Q, As number born alive increases, 12-day weight increases, suggesting a positive relationship between fetal litter size and milk yield in mice.

The effect of foetal litter size on milk yield: cross fostering experiments with mice

Zeitschrift für Tierzüchtung und ZüchtungsbiologieVolume 94, Issue 1-4 p. 66-75 The effect of foetal litter size on milk yield: cross fostering experiments with mice H. Skjervold, Corresponding Author H. Skjervold Department of Animal Genetics and Breeding, Agricultural University of Norway, Ås, NLHDept. of Animal Genetics and Breeding Agricultural University, N-1432 Ås, NLHSearch for more papers by this author H. Skjervold, Corresponding Author H. Skjervold Department of Animal Genetics and Breeding, Agricultural University of Norway, Ås, NLHDept. of Animal Genetics and Breeding Agricultural University, N-1432 Ås, NLHSearch for more papers by this author First published: January‐December 1977 https://doi.org/10.1111/j.1439-0388.1977.tb01535.xCitations: 8AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume94, Issue1-4January‐December 1977Pages 66-75 RelatedInformation