Effects Of Dietary Restriction Research Articles

Sex-specific effects of dietary restriction on physiological variables in Japanese quails.

Nutritional limitation is a common phenomenon in nature that leads to trade-offs among processes competing for limited resources. These trade-offs are mediated by changes in physiological traits such as growth factors and circulating lipids. However, studies addressing the sex-specific effect of nutritional deficiency on these physiological variables are limited in birds. We used dietary restriction to mimic the depletion of resources to various degrees and investigated sex-specific effects on circulating levels of insulin-like growth factor 1 (IGF-1) and triglycerides in Japanese quails (Coturnix japonica) subjected to adlibitum, 20%, 30% or 40% restriction of their daily requirement, for 2 weeks. We also explored the association of both physiological variables with body mass and egg production. While dietary restriction showed no effects on circulating IGF-1, this hormone exhibited a marked sexual difference, with females having 64.7% higher IGF-1 levels than males. Dietary restriction significantly reduced plasma triglyceride levels in both sexes. Females showed more than six-fold higher triglyceride levels than males. Triglyceride levels were positively associated with body mass in females while showed not association in males. Overall, our findings revealed sex-specific expression of physiological variables under dietary restriction conditions, which coincide with body size.

Effects of Dietary Restriction on PGC-1α Regulation in the Development of Age-associated Diseases.

Ageing is the most significant risk factor for a number of non-communicable diseases, manifesting as cognitive, metabolic, and cardiovascular diseases. Although multifactorial, mitochondrial dysfunction and oxidative stress have been proposed to be the driving forces of ageing. Peroxisome proliferator-activated receptor γ coactivator α (PGC-1α) is a transcriptional coactivator central to various metabolic functions, of which mitochondrial biogenesis is the most prominent function. Inducible by various stimuli, including nutrient limitations, PGC-1α is a molecule of interest in the maintenance of mitochondrial function and, therefore, the prevention of degenerative diseases. This review involves a literature search for articles retrieved from PubMed using PGC-1α, ageing, and dietary restriction as keywords. Dietary restriction has been shown to promote tissue-specific PGC-1α expression. Both dietary restriction and PGC-1α upregulation have been shown to prolong the lifespans of both lower and higher-level organisms; the incidence of non-communicable diseases also decreased in fasting mammals. In conclusion, dietary interventions may delay ageing by regulating healthy mitochondria in various organs, presenting the possibility of a new primary prevention for many age-related diseases.

Dietary Restrictions as a Source of Food Insecurity among FGCU Students, Faculty, and Staff

Food insecurity is an issue that creates several challenges for individuals, including health complications, eating disorders, loss of productivity, and reduced ability. While food insecurity tends to be associated with poverty, unemployment, or lack of available food, dietary restrictions may also lead to food insecurity in places where food is otherwise plentiful. Dietary restrictions from allergies, cultural/ religious belief systems, and lifestyle choices could prevent access to food resulting in food insecurity. For example, halal requires believers to follow religious guidelines when eating. People who eat halal food avoid pork, alcohol, and dead animals, and only eat meals that are prepared according to Islamic law. As a result, a person practicing halal could experience food insecurity in places where their dietary considerations are not met. This study consists of a self-perception survey to better understand individuals’ dietary requirements, access to food, and the perceived effects of skipping meals on academic performance, professional work, and mental health. Results show that 70.8% of the participants have some form of dietary restrictions with the common forms coming from allergies (62.1%), personal preferences (31.8%), and cultural/religious beliefs (6.1%). The vast majority of participants with dietary restrictions described some difficulties finding food on campus with some saying that they could not find any appropriate food options. This study seems to indicate that dietary restrictions could be a factor leading to food insecurity, which also affects academic performance and physical and mental health. As a result, we need to invest in more food options, better labeling, and improved education to alleviate the detrimental effects of dietary restrictions on food insecurity.

2,2-Dichloroacetamide exposure induces behavior and memory disorders in mice: Detrimental effects of long-term dietary restriction on neurotoxicity

2, 2-dichloroacetamide (DCAcAm), a nitrogen-containing disinfection byproduct (DBPs), is commonly found in potable water. This study aimed to compare the neurotoxicity of DCAcAm in C57/BL6 mice at both environmentally relevant and higher doses through oral exposure over a 28-day period. Furthermore, the potential effects of dietary restriction (DR) on the cerebral toxicity induced by 20 ppb DCAcAm were examined. The findings indicated that DCAcAm exposure and DR treatment resulted in reduced memory retention and cognitive adaptability in mice. Additionally, higher doses of DCAcAm exposure induced severe brain inflammation and oxidative stress. Metabolic profiling revealed disruptions in fatty acid, energy, and amino acid metabolism in the brain. Remarkably, the negative impacts of 20 ppb DCAcAm on the mice brain were worsened by DR treatment. Analysis of 16S rRNA sequencing revealed notable changes in the composition and structure of intestinal microorganisms after exposure to DCAcAm. This study discovered that DCAcAm has both direct effects on the brain and indirect effects through the microbial-brain-intestinal axis, which collectively result in neurotoxicity and dietary restriction exacerbates these effects. This study provides emerging views on the assessment of the toxicity of nitrogen containing DBPs.

Dietary Restriction Improves Perioperative Neurocognitive Disorders by Inhibiting Neuroinflammation and Gut Microbial Dysbiosis

Anesthesia/surgery have been identified as potential factors contributing to perioperative neurocognitive disorders, with a notably heightened risk observed in aging populations. One of the primary drivers of this impairment is believed to be neuroinflammation, specifically inflammation of hippocampal microglia. Dietary restriction has demonstrated a favorable impact on cognitive impairment across various disorders, primarily by quelling neuroinflammation. However, the precise influence of dietary restriction on perioperative neurocognitive disorders remains to be definitively ascertained. This investigation aims to explore the effects of dietary restriction on perioperative neurocognitive disorders and propose innovative therapeutic strategies for their management. The model of perioperative neurocognitive disorder was induced through exploratory laparotomy under isoflurane anesthesia. Cognitive performance was evaluated using the open field test, Barnes maze test, and fear conditioning test. The enzyme-linked immunosorbent assay (ELISA) was employed to quantify concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in both serum and hippocampal samples. The Western blot technique was utilized to assess expression levels of hippocampal PSD 95, Synaptophysin, TLR4, MyD88, and NF-kB p65. Microglial polarization was gauged using a combination of reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence labeling techniques. We conducted 16S rRNA sequencing to investigate the impact of dietary restriction on the intestinal flora of aged mice following anesthesia/surgery. Our findings indicate that dietary restrictions have the potential to ameliorate anesthesia/surgery-induced cognitive dysfunction. This effect is achieved through the modulation of gut microbiota, suppression of inflammatory responses in hippocampal microglia, and facilitation of neuronal repair and regeneration.

ACS-20/FATP4 mediates the anti-ageing effect of dietary restriction in C. elegans

Dietary restriction is an effective anti-ageing intervention across species. However, the molecular mechanisms from the metabolic aspects of view are still underexplored. Here we show ACS-20 as a key mediator of dietary restriction on healthy ageing from a genetic screen of the C. elegans acyl-CoA synthetase family. ACS-20 functions in the epidermis during development to regulate dietary restriction-induced longevity. Functional transcriptomics studies reveal that elevated expression of PTR-8/Patched is responsible for the proteostasis and lifespan defects of acs-20. Furthermore, the conserved NHR-23 nuclear receptor serves as a transcriptional repressor of ptr-8 and a key regulator of dietary restriction-induced longevity. Mechanistically, a specific region in the ptr-8 promoter plays a key role in mediating the transcription regulation and lifespan extension under dietary restriction. Altogether, these findings identify a highly conserved lipid metabolism enzyme as a key mediator of dietary restriction-induced lifespan and healthspan extension and reveal the downstream transcriptional regulation mechanisms.

PSXIV-9 Effects of Dietary Restriction and One-Carbon Metabolite Supplementation During Early Gestation on the Maternal Gut and Vaginal Microbiota in Cattle

Abstract Maternal diet quality and quantity have significant impacts on both maternal and fetal health and development. The composition and function of the maternal gut microbiome is also significantly influenced by diet. However, little is known about the impact of gestational nutrient restriction on the maternal microbiome during early gestation, which is a critical stage for many developmental processes. Here, we evaluated the effects of dietary restriction and one-carbon metabolite (OCM) supplementation on the ruminal and vaginal microbiota of beef heifers during early pregnancy. For this, 32 beef heifers (approximately 14-month-old) were used in a 2 × 2 factorial experiment with main factors including targeted gain (CON; 0.45 kg/d gain vs. RES; -0.23 kg/d gain), and OCM supplementation (OCM vs. noOCM) (n = 8/treatment). OCM heifers received ruminal-protected methionine (20 g/day) and choline (60 g/day) daily via a fine-ground corn carrier, with weekly intramuscular injections of folate (320 mg) and vitamin B12 (20 mg). The noOCM heifers received only corn carrier and saline injections. Heifers were individually fed and began treatment at breeding (d 0) and remained on treatment until d 63 of gestation. Ruminal fluid and vaginal swab samples were collected at d -2, d 35, and d 63 (at necropsy). Microbiota from samples were assessed using 16S rRNA gene (V3-V4) sequencing. Overall community structure of the ruminal microbiota was affected by gain (PERMANOVA: R2 = 0.04, P < 0.0001), OCM (R2 = 0.013, P = 0.03), time (R2 = 0.16, P < 0.0001) and by their interactions (R2 = 0.08, P = 0.004). The greatest difference in ruminal microbial community structure was between RES and CON heifers (R2 ≥ 0.16, P ≤ 0.003) on d 63. Overall microbial richness (total ASVs) was greater in RES (2,900 vs. 2,737; P = 0.005) but was unaffected by OCM (P = 0.25). Analysis via MaAsLin2 revealed that phyla Firmicutes (31% vs. 22%), Actinobacteriota (0.65% vs. 0.36%) and Chloroflexi were enriched (P < 0.05) in RES heifers. Twenty-five of the 34 differentially abundant genera in the rumen microbiota, including Christensellaceae R7 (5.0% vs 2.6%), Lachnobacterium (2.0% vs. 0.46%), and Butyrivibrio were more relatively abundant in RES; whereas 9 genera including Prevotella (16.5% vs. 31.1%), Ruminococcus (1.6% vs. 2.5%) and Saccharofermentans (0.4% vs. 0.5%) were reduced in RES (P < 0.05) on d 63. Overall vaginal microbiota structure was affected by gain (R2 = 0.02, P = 0.023) and time (R2 = 0.34, P < 0.0001) but not OCM (P >0.05). Community structure of RES was distinct from CON (R2 = 0.16, P = 0.032) on d 63, but microbial community richness and diversity were not influenced by OCM (P > 0.05). On d 63, RES heifers had increased Actinobacteriota (30.5% vs. 17.7%), but reduced Proteobacteriota (6.2% vs. 9.4%) and Fusobacteriota (0.02% vs. 0.94%; P < 0.05). In summary, restricted dietary intake during early gestation induced significant alterations in the ruminal microbiota and its impact also extended to the vaginal microbiota. The composition of these two microbial communities remained largely unaffected by OCM supplement.

Testing for age-dependent effects of dietary restriction on the strength of condition dependence in ejaculate traits in the guppy (Poecilia reticulata).

Ejaculates can be costly to produce and depend on an individual's condition, defined as the pool of resources allocated to fitness. A method for assessing condition dependence is to manipulate resource availability and test for a reduction in trait expression. Here, we assess the effects of dietary restriction on two determinants of reproductive fitness in the guppy Poecilia reticulata-sperm production and sperm motility. Importantly, we administered dietary restriction at distinct developmental stages to test: (1) whether dietary restriction, when applied exclusively to juveniles, compromised the ejaculates of newly mature males; (2) whether any observed effects of dietary restriction seen in (1) were reversible when fish returned to an unrestricted diet; and (3) whether dietary restriction applied exclusively to adults influenced ejaculates. We found detrimental effects of resource limitation on both traits, and these were consistent across the three developmental stages tested. Furthermore, dietary restriction reduced male body weight, but this was partially reversed when diet-stressed juveniles (i.e. group 2) returned to unrestricted diets. This latter result suggests that diet-stressed males may sacrifice growth in order to maintain their investment in ejaculates. Together these findings underscore the importance of resource acquisition in determining the expression of ejaculate traits.

Environmental and genetic factors affecting litter size components in rabbits

In rabbits, ovulation rate is, together with prenatal survival, one of the main limiting factors for litter size. Both components are affected by several factors related to females and their environment. Thus, understanding these components and their factors of variation is key in designing diets, optimisation of reproductive performance and genetic selection. In this review, authors summarise the main components of litter size and their environmental factors of variation. Genetic factors and the main results of genetic selection programmes on components of litter size are also summarised. In this regard, a negative effect of dietary restriction and reduced day light hours is found, as well as a positive effect of body condition, parity order and age of female on ovulation rate. However, an increase in deterioration of oocyte quality has been reported as ovulation rate increases, leading to decreased embryonic and foetal survival. Dietary restriction and heat stress also have a negative effect on embryonic and foetal survival, increasing the failures during gestation while good vascularisation and enough available space in uterine horn are keys to embryonic and foetal survival. Ovulation rate was proposed as indirect selection criterion to improve litter size due to higher heritability. However, this selection was relevant, but it did not modify litter size because of an increase in prenatal mortality. Uterine capacity has been directly related to prenatal survival, although its selection has also been unsuccessful in increasing litter size.

Energy Allocation of the Wolf Spider Pardosa pseudoannulata under Dietary Restriction.

The phenomenon of food shortage is widespread in spider populations, which has a great impact on their growth, development, and survival. Pardosa pseudoannulata is a dominant spider species in rice fields and has an important controlling effect on rice pests. In this study, three feeding levels were tested at the juvenile stage (H, high feeding; M, medium dietary restriction; L, severe dietary restriction) and two at the adult stage (H and L). A total of six feeding levels were tested to explore the effects of dietary restriction on the development, longevity, nutrient content, and predation by P. pseudoannulata [HH (control group), HL, MH, ML, LH, LL]. The results showed that continuous dietary restriction (ML and LL groups) had negative impacts on the growth of P. pseudoannulata and positive impacts on longevity. Spiderlings suffered from dietary restrictions during the juvenile period, and when the restrictions were removed upon reaching adulthood (MH and LH groups), their lifespan started decreasing whilst their weight began returning to normal. This suggested that there might be a trade-off between the growth and longevity of the spider under dietary restrictions. The study also found that when food was severely restricted in the juvenile stage (LH and LL groups), the nutrient contents of the adult spider could return to the same level as the control group, but the predatory ability decreased. When food was moderately restricted in the juvenile stage (MH and ML groups), the predatory ability of the adult spiders improved, while nutrients of the adult spiders declined. Our results will provide an empirical basis for the protection and effective use of dominant spider species in agricultural fields.

Effect of severe dietary restriction on growth and slaughter characteristics of non-selected growing rabbits

This work was carry out to study the effects of dietary restriction by limiting rabbit access to the feeder on fattening performance. A total of 44 weaned rabbits, of 32-35 days, were randomly divided into 2 groups, the control group (C) fed ad-libitum throughout the fattening period and the group with restricted access to the feed restriction (R). The weekly feeding program of the R group consisted of a restricted access time to the feed trough for 5 days (3h/d) and an ad libitum feed distribution for the weekend during the 5 weeks post-weaning. Two weeks before slaughter (10 to 12 weeks of age), the rabbits from the Group R were fed ad libitum. Results showed lower live weights for Group R at 10 weeks of age (R: 1084.7 g vs. C: 1510.7; p<0.05) but similar at 12 weeks of age (R: 1557.2 g vs. C: 1800.9 g; P>0.05). Different daily feed intakes throughout the fattening period and similar average daily gains (R:16.25 g/d vs. C:22.10 g/d; p>0.05). The feed intake index at the end of fattening was significantly higher in control animals (C:4.15 vs. R:3.85, p=0.001). Carcass yield was similar (C: 68.07% vs. R: 65.70%; p>0.05), peri-renal fat weight was higher in control rabbits (C: 27.17g vs. R: 13.67g; p=0.002).The results of the present study indicate the economic interest of using a feed restriction strategy that could be popularized in local rabbit farms.

Nicotinamide riboside and dietary restriction effects on gut microbiota and liver inflammatory and morphologic markers in cafeteria diet–induced obesity in rats

ObjectivesNo specific therapy is available for metabolic dysfunction–associated fatty liver disease. We investigated nicotinamide riboside (NR) and dietary restriction (DR) effects in liver lipids, inflammation, histology, intestinal permeability, and gut microbiota in a cafeteria diet (CAFD)-induced obesity model. MethodsAdult male Wistar rats were randomly assigned to standard diet (SD) or CAFD. After 6 wk, they were subdivided into six groups—SD + vehicle (Veh) (distilled water), SD + NR (400 mg/kg), DR + Veh, DR + NR, CAFD + Veh, and CAFD + NR—for 4 wk more until euthanasia. ResultsCAFD increased the hepatic content of lipids, triacylglycerols, and total cholesterol and promoted hepatomegaly, steatosis, steatohepatitis, and liver fibrosis. DR intervention successfully delayed the onset of CAFD-induced liver abnormalities except for steatosis and fibrosis. CAFD suppressed Sirt1 expression in the liver and DR increased Sirt3 expression. CAFD did not affect hepatic inflammatory genes but DR enhanced Il10 expression while decreasing Il1β expression. CAFD reduced Firmicutes and increased Bacteroidetes and Cyanobacteria, with no changes in intestinal permeability. Gut microbiota patterns in animals exposed to DR were similar to those of animals in SD. NR, specifically in CAFD, reduced hepatic triacylglycerols and total cholesterol deposition and collagen fiber accumulation in the liver and limited the colonization of CAFD-induced Cyanobacteria. NR combined with DR decreased the liver's relative weight and Tnfα expression and suppressed Sirt1 and Sirt3 hepatic expression. ConclusionsThis study suggests that NR can be a potential adjuvant to metabolic dysfunction–associated fatty liver disease therapy, encouraging further research in this field.

Ezetimibe increases resistance to oxidative stress and extends lifespan mimicking dietary restriction in Caenorhabditis elegans

Ezetimibe is an approved drug for lowering plasma LDL (low-density lipoprotein) level via inhibition of cholesterol absorption. Derivatives of ezetimibe reduce inflammatory response and oxidative stress. In the present study, we investigated the effect of dietary supplementation with ezetimibe in response to environmental stressors and found that ezetimibe increases resistance to oxidative stress and ultraviolet irradiation. Ezetimibe also significantly extended lifespan accompanying reduced fertility, which is a common trade-off for longevity in C. elegans. Cellular level of reactive oxygen species was increased and the expression of stress-responsive genes, hsp-16.2 and sod-3, was induced by dietary supplementation with ezetimibe, suggesting a hormetic effect on oxidative stress response and lifespan. Ezetimibe also significantly prevented amyloid beta-induced toxicity and completely reversed increased mortality by high-glucose diet. Nuclear localization of DAF-16 required for the prevention of amyloid beta-induced toxicity was enhanced by ezetimibe supplementation. Lifespan assay using known long-lived mutants, age-1, clk-1, and eat-2, revealed that lifespan extension by ezetimibe specifically overlapped with that of eat-2 mutants, which are genetic models of dietary restriction. Effect of ezetimibe on lifespan of worms fed with diluted bacteria suggested that ezetimibe mimics the effect of dietary restriction on lifespan. These findings suggest that ezetimibe exhibits anti-oxidative and anti-aging effects through hormesis and works as a dietary-restriction mimetic on lifespan extension.

The innate immune signaling component FBXC-58 mediates dietary restriction effects on healthy aging in Caenorhabditis elegans.

Dietary restriction (DR) is a highly effective and reproducible intervention that prolongs longevity in many organisms. The molecular mechanism of action of DR is tightly connected with the immune system; however, the detailed mechanisms and effective downstream factors of immunity that mediate the beneficial effects of DR on aging remain unknown. Here, to investigate the immune signaling that mediates DR effects, we used Caenorhabditis elegans, which has been widely used in research, to understand the underlying molecular mechanisms of aging and immunity. We found that the F-box gene, fbxc-58, a regulator of the innate immune response, is a novel mediator of DR effects on extending the health span of C. elegans. fbxc-58 is upregulated by DR and is necessary for DR-induced lifespan extension and physical health improvement in C. elegans. Furthermore, through DR, fbxc-58 prevents disintegration of the mitochondrial network in body wall muscle during aging. We found that fbxc-58 is a downstream target of the ZIP-2 and PHA-4 transcription factors, the well-known DR mediator, and fbxc-58 extends longevity in DR through an S6 kinase-dependent pathway. We propose that the novel DR effector, fbxc-58, could provide a new mechanistic understanding of the effects of DR on healthy aging and elucidate the signaling mechanisms that link immunity and DR effects with aging.

Effects of dietary restriction on genome stability are sex and feeding regimen dependent.

Preserving genome stability is essential to prevent aging and cancer. Dietary restriction (DR) is the most reproducible non-pharmacological way to improve health and extend lifespan in various species. Whether DR helps to preserve genome stability and whether this effect is altered by experimental variables remain unclear. Moreover, DR research relies heavily on experimental animals, making the development of reliable in vitro mimetics of great interest. Therefore, we tested the effects of sex and feeding regimen (time-restricted eating, alternate day fasting and calorie restriction) on genome stability in CF-1 mice and whether these effects can be recapitulated by cell culture paradigms. Here, we show that calorie restriction significantly decreases the spontaneous micronuclei (MN), a biomarker of genome instability, in bone marrow cells of females instead of males. Alternate day fasting significantly decreases cisplatin-induced MN in females instead of males. Unexpectedly, daily time-restricted eating significantly exacerbates cisplatin-induced MN in males but not in females. Additionally, we design several culture paradigms that are able to faithfully recapitulate the key effects of these DR regimens on genome stability. In particular, 30% reduction of serum, a mimetic of calorie restriction, exhibits a strong ability to decrease spontaneous and cisplatin-induced MN in immortalized human umbilical vein endothelial cells. We conclude that the effects of different DR regimens on genome stability are not universal and females from each diet regimen sustain a more stable genome than males. Our results provide novel insight into the understanding of how DR influences genome stability in a sex and regimen dependent way, and suggest that our in vitro DR mimetics could be adopted to study the underlying molecular mechanisms.

RNA PROCESSING MECHANISMS DURING AGING AND CALORIC RESTRICTION

Abstract Caloric restriction (CR), a reduction in caloric intake without malnutrition, was first described in the 1930s and is a robust model to extend lifespan. While the specific mechanisms that produce delayed aging are still unknown, work has demonstrated the importance of metabolism – dysregulated mitochondrial metabolism is an aging hallmark, while CR upregulates energy metabolism. Crucially, transcriptional regulation plays a key role in implementing this metabolic program although details are still unclear. Splicing factors that are required for the beneficial effects of dietary restriction in nematodes have been identified, and large-scale exon usage changes have been observed across the metabolic network engaged by CR in various tissues from non-human primates, suggesting a translational mechanism that might contribute to how CR delays aging. We will discuss the landscape of RNA processing across multiple organism, tissue, and intervention contexts and provide a broad perspective of how RNA processing contributes to enhanced longevity.

The maternal effects of dietary restriction on Dnmt expression and reproduction in two clones of Daphnia pulex.

The inheritance of epigenetic marks induced by environmental variation in a previous generation is broadly accepted as a mediator of phenotypic plasticity. Transgenerational effects linking maternal experiences to changes in morphology, gene expression, and life history of successive generations are known across many taxa. While the number of studies linking epigenetic variation to ecological maternal effects is increasing rapidly, few if any attempts have been made to investigate molecular mechanisms governing epigenetic functions in the context of ecologically relevant maternal effects. Daphnia make an ideal model for investigating molecular epigenetic mechanisms and ecological maternal effects because they will reproduce asexually in the lab. Daphnia are also known to have strong maternal effects, involving a variety of traits and environmental variables. Using two clones of Daphnia pulex, we investigated the plasticity of life history and DNA methyltransferase (Dnmt) gene expression with respect to food limitation within and across generations. We found strong evidence of genotypic variation of responses of life history and Dnmt expression to low food diets, both within and across generations. In general, effects of offspring diet were larger than either the direct maternal effect or offspring-maternal environment interactions, but the direction of the maternal effect was usually in the opposite direction of the within-generation effect. For both life history and Dnmt expression, we also found that when offspring had low food, effects of the maternal environment were stronger than when offspring had high food.

Does diet influence ejaculate expenditure under experimentally altered risk of sperm competition in guppies?

According to the sperm competition risk (SCR) model, males should increase their investment in ejaculates when there is a high chance that their sperm will compete for fertilization with those from another male. However, as ejaculates are energetically costly to produce, the extent to which males can adjust ejaculate investment may depend on the availability of metabolic resources. We tested these ideas using the guppy, Poecilia reticulata, a livebearing fish known to exhibit strong condition dependence in ejaculate traits and among the highest recorded polyandry rates in any vertebrate. Specifically, we manipulated SCR by visually exposing mature males to females either in the presence (high SCR) or absence (low SCR) of a rival male over 1 month, which comprises a full spermatogenic cycle. To test for condition dependence in male response to SCR, both groups were further subdivided into two diet quantity treatments (high and low), enabling us to test fixed and interactive effects of SCR and diet treatment on ejaculate expenditure (sperm production, sperm length and sperm velocity). Contrary to our predictions, we found no evidence that males increase ejaculate expenditure under high SCR, and indeed report the opposite pattern (higher expenditure under low SCR) for sperm velocity. Furthermore, we found no evidence that dietary restriction (when administered to mature adult males over 1 month) affected any ejaculate traits, leading us to suspect that ejaculates may only be susceptible to dietary restriction effects during a critical ontogenetic stage of development. We discuss these unexpected findings in the context of guppy biology, which may render the species less likely to exhibit long-term adjustments in ejaculates when perceiving short-term changes in SCR. Moreover, the high polyandry rates in this species may mean that the visual presence of a rival is a cue of altered sperm competition intensity, rather than risk.

Influence of feed restriction and subsequent recovery on lactating Charolais cows

One of the potential consequences of global climate change is that forage resources may become more limited at certain times of the year. In this study, 340 primiparous Charolais cows from two experimental farms participated in a feed restriction challenge in order to better understand how lactating beef cattle can adapt to this limitation. Therefore, half of the animals were fed 3 forage units (FU) less than their expected needs (around 30% reduction) from 10 days after calving until they were turned out on grass in April (average duration of 85 days). All animals were then kept together until mid-July (recovery period, average duration of 89 days). Regular measurements were taken of dam weight, body condition score (BCS), and calf weight; three estimates were made of dam milk production during lactation; and the date of each cow's resumption of cyclicity was recorded. On one of the farms, the experiment was extended for two more lactations, for a total of 592 lactations among all the animals examined. The effects of dietary restriction were analyzed using generalized linear models of the phenotyped traits. We found that winter feed restriction in early-lactation Charolais cows affected all traits, with generally similar impacts on the mobilization of body reserves and limitation of milk production. At the end of the winter period, diet-restricted dams were an average of 55 kg lighter than their unrestricted counterparts (corresponding to 0.66 standard deviations, s.d.) and had BCS values that were 0.81 points lower (0.55 s.d.). Similarly, calves from restricted dams were also lighter (20 kg difference, corresponding to 0.68 s.d.), reflecting the reduced milk production of their mothers (-1.7 L at 90 days in milk, corresponding to 0.77 s.d.). On average, feed-restricted primiparous cows resumed cyclicity almost an entire cycle later than their control counterparts (difference of 17 days, corresponding to 0.48 s.d.). For cow traits, the differences between groups remained significant but decreased in magnitude as spring went on, especially for milk production; by the start of the next calving period, the effects of restriction were no longer visible. For calves, however, the differences in weight between groups remained steady, suggesting that the feed restriction occurred too early in their lives for them to be able to experience compensatory growth at refeeding.

Comparison of the Effect of Dietary Restriction and Free Diet on Postoperative Bleeding After Tonsillectomy

Background and Objectives There have been several studies on the factors affecting posttonsillectomy bleeding; however, investigations on the relationship between postoperative bleeding and diet are insufficient. Different countries have different types of food, and while there have been studies on the effects of diet in other countries, no such studies have been reported in Korea. Therefore, we aimed to investigate the relationship between Korean diet and postoperative bleeding after tonsillectomy.Subjects and Method To compare the postoperative bleeding outcomes, patients who underwent tonsillectomy by a single surgeon between January 2017 and 2020 were divided into those who had a diet restriction after surgery and those who had a free diet. Postoperative bleeding outcomes were divided according to the degree of intervention for hemostasis and compared.Results The study included 115 and 124 patients in the diet-restricted group and free-diet group, respectively. There were no statistical differences between the two groups in terms of gender, age, presence of snoring and frequent tonsillitis, and surgical method. Bleeding occurred in four patients in the diet-restricted group and three patients in the free-diet group. There was no statistical difference between the two groups in the frequency and severity of postoperative bleeding.Conclusion Since dietary restriction after tonsillectomy was not helpful to prevent postoperative bleeding, a free and sufficient diet after surgery may prove to be better.