Analyze Diet

Topic:Body Weight

Body weight in horses is a fundamental parameter that influences various aspects of equine management and health. It is a measure of the horse's mass, often assessed using scales or estimated through body condition scoring and weight tapes. Body weight is integral for determining appropriate feed rations, medication dosages, and workload capacities. Variations in body weight can indicate changes in health status, nutritional adequacy, or fitness levels. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies for assessing body weight, its implications on equine health and performance, and its role in management practices.
Changes in Hair Coat Length and Diameter in Blanketed and Nonblanketed Adult Horses in the Winter.
Journal of equine veterinary science    December 9, 2022   Volume 120 104191 doi: 10.1016/j.jevs.2022.104191
DeBoer M, Konop A, Fisher B.Horses are often blanketed during cold weather for numerous reasons including assisting thermoregulation, cleanliness, and anecdotally to decrease hair coat length. However, the impact of blanketing on the hair coat has yet to be evaluated. The objective of this study was to evaluate changes in hair coat length and diameter over time in blanketed and nonblanketed horses during winter. In October 2019, 16 mature adult horses were blocked by breed and BCS and randomly assigned to a blanketed (n = 8) or nonblanketed (n = 8) treatment; blankets were placed. Data was collected between October 2...
Effects of Differences in Fibre Composition and Maturity of Forage-Based Diets on the Fluid Balance, Water-Holding Capacity and Viscosity in Equine Caecum and Colon Digesta.
Animals : an open access journal from MDPI    November 29, 2022   Volume 12, Issue 23 doi: 10.3390/ani12233340
Muhonen S, Philippeau C, Julliand V.Horses are herbivores, and their hindgut functions as a fluid reservoir as forage fibre properties have great impact on the water content of digesta and the milieu in the ecosystem. Our objective was to compare the effect of grass fibre maturity and legume forage on the water-holding capacity (WHC) and viscosity of the equine hindgut and the body weight (BW) and fluid balance of horses. Three diets: concentrate and late harvested grass haylage (35:65 energy ratio) (C); early and late harvested grass haylage (80:20) (G); lucerne and late harvested grass haylage (80:20) (L) were fed to six caecu...
An updated insight on testicular hemodynamics: Environmental, physiological, and technical perspectives in farm and companion animals.
Veterinary research communications    November 18, 2022   Volume 47, Issue 2 323-345 doi: 10.1007/s11259-022-10022-9
Samir H, ElSayed MI, Radwan F, Hedia M, Hendawy H, Hendawy AO, Elbadawy M, Watanabe G.In all organs, control of blood flow is important but might be particularly critical for testicular functions. This is because of the very low oxygen concentration and high metabolic rate of the seminiferous tubules, the physiological temperature of the testis, and its location outside the abdominal cavity. Many factors affect the characteristics of TBF in farm and companion animals, such as environment (thermal and seasonal effects) and physiological (species, breeds, age, body weight, and sexual maturity). Thermal environment stress has detrimental effects on spermatogenesis and consequently...
Exploring human behavior change in equine welfare: Insights from a COM-B analysis of the UK’s equine obesity epidemic.
Frontiers in veterinary science    November 8, 2022   Volume 9 961537 doi: 10.3389/fvets.2022.961537
Furtado T, Perkins E, Pinchbeck G, McGowan C, Watkins F, Christley R.While equine obesity is understood by equine professionals to be a serious and widespread welfare problem, thus far approaches to reducing the prevalence of obesity in the UK's leisure horses have mainly been limited to educating owners about the dangers of obesity in their horses. In human health, approaches to behavior change encourage holistic thinking around human behavior, recognizing the importance of the connection between the individuals' knowledge, attitudes, habits, and the social and physical environments. This study used qualitative data from interviews with horse owners and profes...
Age and sex correlate with bony changes and anatomic variations of the lumbosacroiliac region of the vertebral column in a mixed population of horses.
Journal of the American Veterinary Medical Association    November 8, 2022   Volume 261, Issue 2 258-265 doi: 10.2460/javma.22.07.0293
Scilimati N, Beccati F, Dall'Aglio C, Di Meo A, Pepe M.To provide a postmortem description of anatomic variations and changes of the lumbosacroiliac region in horses. The authors hypothesized that lesion severity would increase with age and body weight and correlate to anatomic variations. Lumbosacroiliac vertebral specimens from 38 horses (mean age, 16 years; range, 5 to 30 years) that died or were euthanized for reasons unrelated to the study between November 2019 and October 2021. The lumbosacroiliac region of the vertebral column was removed from each cadaver. After dissection, disarticulation, and boiling, the anatomic specimens were examined...
Effects of different winter climates in Japan on body composition of young Thoroughbreds in training.
The Journal of veterinary medical science    October 14, 2022   Volume 84, Issue 12 1585-1594 doi: 10.1292/jvms.22-0378
Ishimaru M, Matsui A, Seki K, Korosue K, Akiyama K, Mizukami H, Yoshida T, Taya K.Changes in the body composition of 50 Thoroughbreds colts and fillies, born between 2004 and 2010, were compared between those reared at the Hidaka Training and Research Center (Hidaka), Hokkaido, which is extremely cold in winter, and those reared at the Miyazaki Yearling Training Farm (Miyazaki), Kyushu, which is mildly cold in winter. The horses were divided into two sex groups and reared and trained in Hidaka or Miyazaki for 7 months from October of one year of age to April of two years of age. Body weight (BW), rump fat thickness (RFT), fat-free mass (FFM), and percentage of fat (%F) were...
A starch-rich treat affects enteroinsular responses in ponies.
Journal of the American Veterinary Medical Association    October 6, 2022   Volume 260, Issue S3 S94-S101 doi: 10.2460/javma.22.06.0272
Sibthorpe PEM, Fitzgerald DM, Chen L, Sillence MN, de Laat MA.To determine the effect of a starch-rich treat, added to the daily diet of ponies for 10 days, on enteroinsular responses to meal consumption. 10 mixed-breed adult ponies owned by Queensland University of Technology were used in the study. Six ponies were metabolically healthy, and 4 were insulin dysregulated at the start of the study, according to the results of an in-feed oral glucose test. A bread-based treat was offered twice daily for 10 days, adding 0.36 ± 0.04 g/kg body weight (BW) carbohydrates to the daily diet. Before and after treatment, the intestinal capacity for simple carbohydr...
[Is alfalfa hay an alternative to meadow hay in equine nutrition?].
Schweizer Archiv fur Tierheilkunde    October 5, 2022   Volume 164, Issue 10 721-731 doi: 10.17236/sat00371
Köninger M, von Velsen-Zerweck A, Eiberger C, Jilg A, Töpper A, Visscher C, Reckels B, Vervuert I.Roughage alternatives for equine nutrition must be found due to the increasing climatic challenges. The aim of this study was to examine the nutrient composition and feed hygiene of alfalfa hay in comparison to meadow hay and to investigate the acceptance, weight development and faecal quality of broodmares fed alfalfa hay. The feed used was examined for nutrient content and hygiene status according to the standards of the Verband Deutscher Landwirtschaftlicher Untersuchungs- und Forschungsanstalten (VDLUFA). Twenty adult pregnant warmblood mares were fed in two groups (n=10) with a defined am...
Are Horse Owners Able to Estimate Their Animals’ Body Condition Score and Cresty Neck Score?
Veterinary sciences    October 3, 2022   Volume 9, Issue 10 544 doi: 10.3390/vetsci9100544
Busechian S, Turini L, Sgorbini M, Pieramati C, Pisello L, Orvieto S, Rueca F.Obesity and overconditioning are becoming more prevalent in horses, and are influencing the animal's health, activity, and reproductive efficiency. Body condition score (BCS) and cresty neck score (CNS) have been correlated with the development of various diseases. Many of the papers in the literature evaluate the prevalence of obesity and overconditioning in horse populations considering BCS given by owners. The aim of this study was to evaluate the validity of the owners' estimation of the degree of equine obesity or overconditioning by comparing BCS and CNS provided by each owner and a boar...
A Novel A > G Polymorphism in the Intron 1 of LCORL Gene Is Significantly Associated with Hide Weight and Body Size in Dezhou Donkey.
Animals : an open access journal from MDPI    September 27, 2022   Volume 12, Issue 19 2581 doi: 10.3390/ani12192581
Wang T, Shi X, Liu Z, Ren W, Wang X, Huang B, Kou X, Liang H, Wang C, Chai W.Several studies have shown the association between the ligand-dependent nuclear receptor compression-like protein (LCORL) gene and body size in horses, pigs and donkeys. Based on previous studies, the LCORL gene was hypothesized to be associated with growth traits and hide weight in Dezhou donkeys. In this study, we aimed to reveal the variation of the LCORL gene in the Dezhou donkey and explore whether the gene is associated with hide weight and body size. In this study, genetic polymorphisms in the LCORL gene of the Dezhou donkey were studied using targeted sequencing technology, and single ...
Application of the Two-Dimensional Entropy Measures in the Infrared Thermography-Based Detection of Rider: Horse Bodyweight Ratio in Horseback Riding.
Sensors (Basel, Switzerland)    August 13, 2022   Volume 22, Issue 16 6052 doi: 10.3390/s22166052
Domino M, Borowska M, Zdrojkowski Ł, Jasiński T, Sikorska U, Skibniewski M, Maśko M.As obesity is a serious problem in the human population, overloading of the horse's thoracolumbar region often affects sport and school horses. The advances in using infrared thermography (IRT) to assess the horse's back overload will shortly integrate the IRT-based rider-horse fit into everyday equine practice. This study aimed to evaluate the applicability of entropy measures to select the most informative measures and color components, and the accuracy of rider:horse bodyweight ratio detection. Twelve horses were ridden by each of the six riders assigned to the light, moderate, and heavy gr...
Population structure and genomic footprints of selection in five major Iranian horse breeds.
Animal genetics    August 2, 2022   Volume 53, Issue 5 627-639 doi: 10.1111/age.13243
Salek Ardestani S, Zandi MB, Vahedi SM, Janssens S.The genetic structure and characteristics of Iranian native breeds are yet to be comprehensibly investigated and studied. Therefore, we employed genomic information of 364 Iranian native horses representing the Asil (n = 109), Caspian (n = 40), Dareshuri (n = 44), Kurdish (n = 95), and Turkoman (n = 76) breeds to reveal the genetic structure and characteristics. For these and 19 other horse breeds, principal component analysis, Bayesian model-based, Neighbor-Net, and bootstrap-based TreeMix approaches were applied to investigate and compare their genetic structure. Additionally, thre...
Effects of a Supplement Containing Cannabidiol (CBD) on Sedation and Ataxia Scores and Health.
Journal of equine veterinary science    July 23, 2022   Volume 117 104085 doi: 10.1016/j.jevs.2022.104085
St Blanc MP, Chapman AM, Keowen ML, Garza F, Liu CC, Gray L, Andrews FM.Supplements containing Cannabidiol (CBD) are available for horses, however, few studies have been published on their effects on behavior and health parameters. The purpose of this study was to determine if a daily oral supplement containing CBD would cause sedation, ataxia or alterations in other health parameters during administration for 56 days. Twenty clinically healthy adult Thoroughbred horses were housed in stalls. Before treatment was initiated, a complete physical examination, complete blood count (CBC) and biochemical panel were evaluated. In addition, horses were examined for sedati...
Effect of Weight Change on Markers of Bone Turnover and Phosphorus Excretion.
Journal of equine veterinary science    July 16, 2022   Volume 118 104080 doi: 10.1016/j.jevs.2022.104080
Fowler AL, Pyles MB, Hayes SH, Crum AD, Harris PA, Krotky A, Lawrence LM.There is little information about how weight change in horses impacts bone turnover and the metabolism of minerals associated with bone. This study evaluated weight change in mature horses as a factor that could alter bone turnover and fecal P output. Fifteen horses (555 ± 8 kg) were assigned to three treatments: weight loss (LO; n = 5), weight maintenance (MA; n = 5), and weight gain (GA; n = 5). Diets contained 75%, 100%, and 145% of maintenance digestible energy requirements for the three treatments, respectively, but contained similar amounts of protein and minerals. At the end of t...
Relationships between the age and blood test results or body sizes in Noma horses.
Journal of equine science    July 6, 2022   Volume 33, Issue 2 27-30 doi: 10.1294/jes.33.27
Inoue Y, Ono T, Hisaeda K, Yamada Y, Hata A, Shimokawa T, Miyama , Shibano K, Ohzawa E, Kitagawa H, Iwata E.The objective of this study is to analyze the relationships between the age and blood test results or body sizes in Noma horses by using the results of periodical health examination. Out of 45 hematological or physical items examined, statistically significant, but loose correlations were observed in 14 items. Red blood cell count, activities of aspartate aminotransferase, alkaline phosphatase, and creatinine kinase, concentrations of calcium and inorganic phosphorus decreased with aging. Conversely, mean corpuscular volume, mean corpuscular hemoglobin, lipase activity, γ-globulin and chlorid...
An exercise-inducible metabolite that suppresses feeding and obesity.
Nature    June 15, 2022   Volume 606, Issue 7915 785-790 doi: 10.1038/s41586-022-04828-5
Li VL, He Y, Contrepois K, Liu H, Kim JT, Wiggenhorn AL, Tanzo JT, Tung AS, Lyu X, Zushin PH, Jansen RS, Michael B, Loh KY, Yang AC, Carl CS....Exercise confers protection against obesity, type 2 diabetes and other cardiometabolic diseases1-5. However, the molecular and cellular mechanisms that mediate the metabolic benefits of physical activity remain unclear6. Here we show that exercise stimulates the production of N-lactoyl-phenylalanine (Lac-Phe), a blood-borne signalling metabolite that suppresses feeding and obesity. The biosynthesis of Lac-Phe from lactate and phenylalanine occurs in CNDP2+ cells, including macrophages, monocytes and other immune and epithelial cells localized to diverse organs. In diet-induced obese mice,...
Evaluation of peripheral blood polymorphonuclear cell functions after an oral carbohydrate overload in obese and insulin dysregulated horses.
Veterinary immunology and immunopathology    June 13, 2022   Volume 250 110455 doi: 10.1016/j.vetimm.2022.110455
Salinas C, Espinosa G, Morales N, Henríquez C, Morán G, Gajardo G, Burgos RA, Uberti B.Obesity and insulin dysregulation (ID) are increasingly prevalent conditions in equid populations worldwide. Immune impairment is well described in humans with metabolic dysfunction and is reported but still incompletely understood in horses. This study evaluated the effect of acute induced transient hyperglycemia on apoptosis, phagocytosis and oxidative burst activity of peripheral blood polymorphonuclear cells (PMN) of lean and obese adult horses with or without insulin dysregulation. Seventeen adult horses were allocated into three groups based on their body condition score (BCS) and metabo...
Incidence of Severe Hypoxemia in Anesthetized Horses Undergoing Emergency Exploratory Laparotomy.
Journal of equine veterinary science    May 31, 2022   Volume 116 104026 doi: 10.1016/j.jevs.2022.104026
Marchese GA, Crystal J, Louro LF.Prevalence and risk factors of severe hypoxemia in anesthetized horses undergoing emergency exploratory laparotomy are sparsely documented. The aim of this study was to report incidence of severe hypoxemia ( PaO2 < 60 mmHg) in horses undergoing emergency exploratory laparotomy and identify potential risk factors for this complication. A single center retrospective cross sectional designed was used. Clinical data of 714 horses undergoing general anesthesia for emergency explorative laparotomy were reviewed. A backward stepwise elimination procedure was used to determine the final multivariab...
Welfare Concerns for Mounted Load Carrying by Working Donkeys in Pakistan.
Frontiers in veterinary science    May 27, 2022   Volume 9 886020 doi: 10.3389/fvets.2022.886020
Bukhari SSUH, Rosanowski SM, McElligott AG, Parkes RSV.Working donkeys () are vital to people's livelihoods. They are essential for carrying goods, however, globally, overloading is one of the primary welfare concerns for working donkeys. We studied mounted load carrying by donkeys and associated factors in Pakistan. A cross-sectional study of donkey owners ( = 332) was conducted, and interviews were undertaken based on a questionnaire. Owners estimated that the median weight of their donkeys was 110 kg [interquartile range (IQR) 100-120 kg], and that they carried a median mounted load of 81.5 kg (IQR 63-99 kg). We found that 87.4% of donkeys carr...
Puberal and Adolescent Horse Riders’ Fitness during the COVID-19 Pandemic: The Effects of Training Restrictions on Health-Related and Functional Motor Abilities.
International journal of environmental research and public health    May 24, 2022   Volume 19, Issue 11 6394 doi: 10.3390/ijerph19116394
The aim of the study was to analyse the fitness level of young horse riders before and after 12 weeks of training restrictions instituted due to the COVID-19 emergency. Anthropometrical measure assessment and an eight-items fitness test battery were administered to 61 puberal and adolescent female amateur horse riders. Subjects were evaluated within 3 weeks before (pre-tests) the period of training restrictions and on the first day of normal training after it (post-tests). Post-test results showed significant increases in body weight (Z: −1.732; p value: 0.001; ES: −0.157) and BMI (F: 9.91...
Body Weight Prediction from Linear Measurements of Icelandic Foals: A Machine Learning Approach.
Animals : an open access journal from MDPI    May 11, 2022   Volume 12, Issue 10 doi: 10.3390/ani12101234
Satoła A, Łuszczyński J, Petrych W, Satoła K.Knowledge of the body weight of horses permits breeders to provide appropriate feeding and care regimen and allows veterinarians to monitor the animals' health. It is not always possible to perform an accurate measurement of the body weight of horses using horse weighbridges, and therefore, new body weight formulas based on biometric measurements are required. The objective of this study is to develop and validate models for estimating body weight in Icelandic foals using machine learning methods. The study was conducted using 312 data records of body measurements on 24 Icelandic foals (12 col...
Epidemiological survey, general blood biochemistry, and histological examination of slaughtered heavy horse breeds with hemorrhage in the adipose tissue in the crest of the neck.
Journal of equine science    April 19, 2022   Volume 33, Issue 1 7-12 doi: 10.1294/jes.33.7
Harada K, Kanemitsu S, Akioka K, Fujita K, Nishi Y, Taura Y, Sasaki N.Fifty-four slaughtered horses were classified into groups having adipose tissue in the crest of the neck with or without hemorrhage (AH and NH groups, respectively). Blood biochemical tests (Alb, TP, T-bil, GOT, GPT, LDH, T-cho, and BUN) and an epidemiological survey (age, gender, weight, origin, breed, BCS, CNS, and hoof disease) were performed. T-bil tended to be high, while the other parameters were normal. Weight, BCS, and CNS were higher in the AH group (P<0.05). GOT was lower in the AH group (P<0.05). It was suspected that the horses in the AH group had lipomatosis. It was assumed ...
Seasonal Insulin Responses to the Oral Sugar Test in Healthy and Insulin Dysregulated Horses.
Journal of equine veterinary science    April 8, 2022   Volume 113 103945 doi: 10.1016/j.jevs.2022.103945
Macon EL, Harris P, Barker VD, Adams AA.Seasonal effects on the oral sugar test (OST), used to monitor insulin dysregulation (ID) status to help reduce laminitis risk, are poorly understood in the ID horse. Resting, (basal) insulin (T0) and 60-minute (T60) OST (0.15 mL/Kg BW Karo Light Corn Syrup) insulin responses were evaluated, once per each season over 2 years, in ID (n = 11 14.9 ± 4.3 years; mean ± SD) and non-insulin dysregulated (NID: n = 11 16.4 ± 5.3 years; mean ± SD) horses housed on the same farm. Seasonal morphometric measurements were collected: bodyweight (BW), body-condition scores (BCS), and cresty neck score...
Reproducibility of the body condition score assessment in Silesian horses, using the 9-point BCS scale.
Veterinary research communications    March 22, 2022   Volume 47, Issue 1 273-278 doi: 10.1007/s11259-022-09916-5
Pyrek P, Siwinska N, Zak-Bochenek A.Control of body condition is an important aspect of horse management. Its correct evaluation, and the possibility of using universal indicators are of key importance for preserving the animals' wellbeing and for providing them with proper care. The objective of this study was to evaluate the agreement between body condition scores assessed by teams and individuals, using the 9-point Body Condition Score scale created by Henneke. The evaluation of a herd of 49 healthy adult Silesian horses was conducted by veterinary medicine students with adequate training in body condition assessment. Group a...
Altrenogest treatment reduces the stress response of three-year-old warmblood mares during their initial equestrian training.
Domestic animal endocrinology    March 20, 2022   Volume 80 106728 doi: 10.1016/j.domaniend.2022.106728
Kaps M, Lutzer A, Gautier C, Nagel C, Aurich J, Aurich C.Horse mares are frequently treated with the progestin altrenogest with the aim to suppress estrous behavior and its negative impact on equestrian performance. Progestogens, however, also have sedative effects in males, and females of different species. The aim of our study was therefore to investigate altrenogest-induced changes in the stress response of female horses during initial equestrian training. Three-yr-old Warmblood mares were randomly assigned to treatment with altrenogest (ALT; 0.044 mg/kg once daily; n = 6) or sunflower oil (CON; n = 5) for 12 wk during training. At predefined...
Preliminary Study on the Connection Between the Mineral Profile of Horse Hooves and Tensile Strength Based on Body Weight, Sex, Age, Sampling Location, and Riding Disciplines.
Frontiers in veterinary science    March 7, 2022   Volume 8 763935 doi: 10.3389/fvets.2021.763935
Rueda-Carrillo G, Rosiles-Martínez R, Hernández-García AI, Vargas-Bello-Pérez E, Trigo-Tavera FJ.Hoof mineral profile is important as it could affect locomotion. Factors such as body weight, sex, age, and riding disciplines affect hoof mineral profile. In Mexico and globally, studies are needed on the characterization of mineral profile of hooves and tensile strength, as this could help to prevent overgrowth or microfractures. Therefore, in the present survey, 165 samples of equine hoof cuttings from different sex, ages, breeds, and riding disciplines from different regions of Mexico were analyzed for their mineral composition, and a universal testing machine was used to measure tensile s...
Development of Foals Until One Year of Age When the Dam was Exposed to Blue Monochromatic Light Directed at One Eye During Late Pregnancy.
Journal of equine veterinary science    March 5, 2022   Volume 112 103922 doi: 10.1016/j.jevs.2022.103922
Lutzer A, Nagel C, Aurich J, Murphy BA, Aurich C.In horses, blue LED light directed at one eye of pregnant mares shortens gestation length and results in the birth of foals with lower wither heights, similar weight and reduced hair length compared to controls. In this study, we have therefore analysed postnatal development of foals born to either blue LED light-treated (n = 20) or control mares (n = 20). Size, weight and hair coat changes were determined for 1 year and heart rate, heart rate variability (HRV) and selected haematology parameters for 1 month. Haematocrit decreased (P < .001) and leukocyte and lymphocyte counts increased...
Magnetic resonance imaging of the normal equine pituitary gland. Hobbs KJ, Porter E, Wait C, Dark M, MacKay RJ.Magnetic resonance imaging is increasingly available for evaluation of horses with suspected pituitary adenomas; however, published studies describing the MRI features of normal equine pituitary glands are currently lacking. This retrospective, descriptive, anatomic study describes the MRI appearance and size of presumed normal equine pituitary glands and assesses potential correlations between pituitary size, brain size, and patient weight. These findings serve as a reference for MRI evaluation of the equine pituitary gland. Inclusion criteria consisted of adult horses (2-15 years old), over ...
Associations between styloid process sheath CT sizes and age, body weight, and breed in horses. Whitty JA, Miller AV, Miller AD, Carney PC, Scrivani PV.The styloid process sheath (SPS) is a part of the tympanic temporal bone and an incomplete bony sleeve surrounding the styloid process, tympanohyoid cartilage, and dorsal part of the stylohyoid bone. In horses undergoing head CT, we observed a range of SPS sizes and questioned whether differences were early features of temporohyoid osteoarthropathy (THO) or normal anatomic variations associated with age, body weight, sex, or breed. We hypothesized that SPS sizes were positively correlated with age and body weight, but not with sex or breed. Using a convenience population of horses that underwe...
Maternal effect on first-year growth of Hokkaido native foals kept outdoors all year round.
Animal science journal = Nihon chikusan Gakkaiho    February 12, 2022   Volume 93, Issue 1 e13694 doi: 10.1111/asj.13694
Huricha , Kawai M, Inose Y, Yamada F, Ninomiya S.In this study, we investigated maternal effects on the growth of Hokkaido native horses kept outdoors throughout the year. We used the data on body weight (BW), height at withers (HW), heart girth (HG), and cannon circumference (CC) of 517 foals during the first year of life to (1) examine the growth patterns by comparing six linear mixed models and (2) analyze the maternal effect on BW, HW, HG, and CC for each month by estimating variance components. The segmented polynomial third-order regression equation was selected as the best model for all the traits. The estimated proportion of variance...