Analyze Diet

Topic:Organic Matter

Organic matter in the context of equine health refers to decomposed plant and animal material found in soil, which contributes to nutrient availability and soil structure. It plays a role in maintaining pasture quality, which directly impacts the diet and overall health of horses. Organic matter influences soil water retention, aeration, and microbial activity, all of which are important for the growth of forage consumed by horses. This page compiles peer-reviewed research studies and scholarly articles that explore the composition, benefits, and management of organic matter in equine environments, as well as its implications for horse nutrition and health.
Capacity for colonization and degradation of horse manure and wheat-straw-based compost by different strains of Agaricus subrufescens during the first two weeks of cultivation.
Bioresource technology    December 29, 2012   Volume 131 266-273 doi: 10.1016/j.biortech.2012.12.141
Farnet AM, Qasemian L, Peter-Valence F, Ruaudel F, Savoie JM, Ferré E.The potential of Agaricus subrufescens strains to colonize and transform horse manure and wheat-straw-based mushroom compost under the physico-chemical conditions typically used for Agaricus bisporus was assessed. Lignocellulolytic activities, H2O2 production and substrate transformation (assessed via CP/MAS NMR of (13)C) for certain A. subrufescens strains were similar or even greater than those obtained for an A. bisporus strain used as control. Moreover, the functional diversity of the microbial communities of the substrate was not altered by the growth of A. subrufescens after 2weeks. Thes...
Apparent digestibility of wheat bran and extruded flax in horses determined from the total collection of feces and acid-insoluble ash as an internal marker.
Animal : an international journal of animal bioscience    March 23, 2012   Volume 6, Issue 2 227-231 doi: 10.1017/S1751731111001297
De Marco M, Miraglia N, Peiretti PG, Bergero D.Several studies have reported data on comparisons between two methods: the total collection of feces and the internal markers method. The aim of this study was to assess the apparent digestibility of two concentrates and to compare the apparent digestion coefficients using the total collection of feces and acid-insoluble ash (AIA) as the internal marker method. In 2009, six adult geldings aged between 3 and 11 years, with an average weight per trial of 543, 540 and 542 kg, respectively, were used to determine the apparent digestibility by means of three in vivo digestibility trials on hay, hay...
Thirty-year amendment of horse manure and chemical fertilizer on the availability of micronutrients at the aggregate scale in black soil.
Environmental science and pollution research international    February 2, 2012   Volume 19, Issue 7 2745-2754 doi: 10.1007/s11356-012-0774-7
Fan J, Ding W, Chen Z, Ziadi N.This study evaluates manure and chemical fertilizer effects on micronutrient (Fe, Mn, Cu, and Zn) content and availability in crops. Methods: Seven treatments were selected, including three conventional fertilization treatments (NP, horse manure (M), and NP plus M (NPM)), three corresponding double rate fertilization (N2P2, M2, and N2P2M2), and a CK. Soil samples were collected and separated into four aggregates by wet-sieving in September 2009. Corn samples were collected and analyzed simultaneously. Results: Treatment N2P2 increased DTPA extractable Fe, Mn, and Cu in soil by 732%, 388%, and ...
Influence of different mixing ratios on in-vessel co-composting of sewage sludge with horse stable straw bedding waste: maturity and process evaluation.
Waste management & research : the journal of the International Solid Wastes and Public Cleansing Association, ISWA    October 10, 2011   Volume 29, Issue 11 1164-1170 doi: 10.1177/0734242X11420600
Wong JW, Selvam A, Zhao Z, Yu SM, Law AC, Chung PC.Composting sewage sludge alone would reduce the decomposition efficiency due to free limited porosity in sludge. To alleviate this, the use of horse stable straw bedding waste (HSB) was evaluated as a co-composting material with sewage sludge in a 10 tonnes day(-1) in-vessel composter for a period of 7 days before curing in a static aeration pile. Sludge was mixed with HSB at 1 : 1.5 (HSL) and 1 : 2.9 (LSL) on a fresh weight basis. After a composting period of 56 days, both mixing ratios demonstrated to be feasible with LSL having a better organic decomposition and a shorter time to reach matu...
Effects of bedding type on compost quality of equine stall waste: implications for small horse farms.
Journal of animal science    September 9, 2011   Volume 90, Issue 3 1069-1075 doi: 10.2527/jas.2010-3805
Komar S, Miskewitz R, Westendorf M, Williams CA.Our objective in this study is to compare 4 of the most common bedding materials used by equine operations on the chemical and physical characteristics of composted equine stall waste. Twelve Standardbred horses were adapted to the barn and surrounding environment for 2 wk before the start of the study. Groups of 3 horses were bedded on 1 of 4 different bedding types (wood shavings, pelletized wood materials, long straw, and pelletized straw) for 16 h per day for 18 d. Stalls were cleaned by trained staff daily, and all contents removed were weighed and stored separately by bedding material on...
Solid-state anaerobic digestion of spent wheat straw from horse stall.
Bioresource technology    July 26, 2011   Volume 102, Issue 20 9432-9437 doi: 10.1016/j.biortech.2011.07.062
Cui Z, Shi J, Li Y.The spent wheat straw from horse stall bedding has lower cellulose and hemicellulose contents, but higher volatile fatty acid content than raw wheat straw. Biogas production from solid-state anaerobic digestion (SS-AD) of spent wheat straw and raw wheat straw was compared in this study. The SS-AD tests were conducted at 22% total solids (TS) content using inoculum from a liquid AD system at three feedstock-to-inoculum (F/I) ratios of 2.0, 4.0, and 6.0. Daily methane yields of spent wheat straw peaked 8 and 3 days earlier than those of raw wheat straw at F/I ratios of 2.0 and 4.0, respectively....
Long-term effects of endurance training on total tract apparent digestibility, total mean retention time and faecal microbial ecosystem in competing Arabian horses.
Equine veterinary journal. Supplement    May 27, 2011   Issue 38 387-392 doi: 10.1111/j.2042-3306.2010.00188.x
Goachet AG, Varloud M, Philippeau C, Julliand V.In endurance horses, commonly fed 80% forage, energy is provided mainly by VFA produced in the hindgut during cell wall degradation, but cell wall digestibility has been reported to be impaired by exercise. Objective: To assess the influence of a long-term endurance conditioning on cell wall digestion in horses. Methods: The total tract apparent digestibility of dry matter, organic matter and fibrous constituents, solid and liquid total mean retention time and the faecal microbial ecosystem of purebred Arabian horses were measured for 2 years in 2 longitudinal experiments. Methods: Performed a...
A comparative study of the apparent total tract digestibility of carbohydrates in Icelandic and Danish warmblood horses fed two different haylages and a concentrate consisting of sugar beet pulp and black oats.
Archives of animal nutrition    December 1, 2010   Volume 64, Issue 5 343-356 doi: 10.1080/1745039X.2010.504606
Jensen RB, Brokner C, Knudsen KE, Tauson AH.Four Icelandic (ICE) and four Danish Warmblood (DW) horses were used in a crossover study with two treatments to investigate the effect of breed and the effect of stage of maturity of haylage on the apparent total tract digestibility (ATTD) of a diet consisting of sugar beet pulp, black oats and haylage early or late cut. Fibre was analysed as crude fibre (CF), acid detergent fibre (ADF), neutral detergent fibre (NDF) and dietary fibre (DF = non-starch polysaccharides (NSP) plus lignin). In haylage all analysed fibre fractions increased with advancing stage of maturity, with the cell wall comp...
Aqueous 2% geraniol as a mosquito repellent failed against Aedes aegypti on ponies.
Journal of the American Mosquito Control Association    November 3, 2010   Volume 26, Issue 3 340-341 doi: 10.2987/10-6000.1
Reeves WK, Miller MM.Organic insect repellents are of interest to many agricultural producers and animal owners. Geraniol, a plant-derived alcohol, is naturally produced by a wide range of plants and is a US Environmental Protection Agency minimum risk pesticide. Previous studies have shown various concentrations of geraniol repel or kill mosquitoes; however, geraniol might cause allergic contact dermatitis in humans or animals. We tested a commercially available 2% aqueous solution of geraniol on ponies as a mosquito repellent. Five trials were conducted on ponies treated with a 60-ml aerosol mist (30 ml per side...
Methane output of rabbits (Oryctolagus cuniculus) and guinea pigs (Cavia porcellus) fed a hay-only diet: implications for the scaling of methane production with body mass in non-ruminant mammalian herbivores.
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology    October 30, 2010   Volume 158, Issue 1 177-181 doi: 10.1016/j.cbpa.2010.10.019
Franz R, Soliva CR, Kreuzer M, Hummel J, Clauss M.It is assumed that small herbivores produce negligible amounts of methane, but it is unclear whether this is a physiological peculiarity or simply a scaling effect. A respiratory chamber experiment was conducted with six rabbits (Oryctolagus cuniculus, 1.57±0.31 kg body mass) and six guinea pigs (Cavia porcellus, 0.79±0.07 kg) offered grass hay ad libitum. Daily dry matter (DM) intake and DM digestibility were 50±6 g kg⁻⁰·⁷⁵ d⁻¹ and 55±6% in rabbits and 59±11 g kg⁻⁰·⁷⁵ d⁻¹ and 61±3% in guinea pigs, respectively. Methane production was similar for both species (0.2...
Comparison of grass haylage digestibility and metabolic plasma profile in Icelandic and Standardbred horses.
Journal of animal physiology and animal nutrition    August 27, 2010   Volume 95, Issue 3 273-279 doi: 10.1111/j.1439-0396.2010.01049.x
Ragnarsson S, Jansson A.The aim of the present study was to compare digestibility and metabolic response in Icelandic and Standardbred horses fed two grass haylages harvested at different stages of maturity. Six horses of each breed were used in a 24-day change-over design. A total collection of faeces was made on days 15-17 and 22-24. Blood samples were collected on day 24 of each period and analysed for total plasma protein (TPP), plasma urea, non-esterified fatty acids, cortisol and insulin concentration. There were no differences in digestibility coefficients of crude protein, neutral detergent fibre or energy be...
Definite coordination arrangement of organometallic palladium complexes accumulated on the designed interior surface of apo-ferritin.
Chemical communications (Cambridge, England)    August 23, 2010   Volume 47, Issue 1 170-172 doi: 10.1039/c0cc02221g
Wang Z, Takezawa Y, Aoyagi H, Abe S, Hikage T, Watanabe Y, Kitagawa S, Ueno T.Apo-ferritin (apo-Fr) mutants are used as scaffolds to accommodate palladium (allyl) complexes. Various coordination arrangements of the Pd complexes are achieved by adjusting the positions of cysteine and histidine residues on the interior surface of the apo-Fr cage.
Digestibility and nutrient retention of perennial peanut and bermudagrass hays for mature horses.
Journal of animal science    February 12, 2010   Volume 88, Issue 6 2055-2061 doi: 10.2527/jas.2009-2092
Eckert JV, Myer RO, Warren LK, Brendemuhl JH.Mature horses were used to determine apparent DM, OM, NDF, and CP digestibility values of 2 bermudagrass (BG; Cynodon dactylon) hays, Coastal (CB) and Tifton 85 (T85), and Florigraze perennial peanut (PP; Arachis glabrata) hay. In addition, N, Ca, and P balances were determined in horses fed those hays. Five mature Thoroughbred geldings and 1 Quarter Horse gelding (mean initial BW = 542 +/- 37 kg) were used (5 horses for the last period) in a 3 x 3 repeated Latin square design, with 2 horses per hay and 3 adjustment and collection periods. Horses were randomly assigned to pairs and the initial...
Effect of diet on mechanical properties of horse’s hair.
Acta of bioengineering and biomechanics    February 6, 2010   Volume 11, Issue 3 53-57 
Kania M, Mikołajewska D, Marycz K, Kobielarz M.The aim of this research was to assess the effect of diet supplementation with zinc and copper, in different chemical forms (organic and inorganic), on the mechanical properties of the hair of healthy English thoroughbred horses. Hairs were taken from 18 horses which had been fed with oats and hay for a period of 110 days. Twelve of the horses had been additionally given a daily dose of 700 g of highquality 44-ingredients Fohlengold St-Hippolyt muesli made by Muhle Ebert Dilheim. Six of them had received the muesli-containing organic zinc and copper (OS), while the other six horses had receive...
Impact of feeding level on digestibility of a haylage-only diet in Icelandic horses.
Journal of animal physiology and animal nutrition    November 17, 2009   Volume 94, Issue 5 623-627 doi: 10.1111/j.1439-0396.2009.00947.x
Ragnarsson S, Lindberg JE.Eight mature Icelandic geldings were used in an experiment arranged as a change-over design to evaluate the effect of feeding level on the digestibility of a high-energy haylage-only diet. The horses were fed a low feeding level 10.7 g dry matter (DM)/kg body weight (BW) (maintenance) and a high feeding level 18.1 g DM/kg BW (1.5 × maintenance) during two 23 days experimental periods. Total collection of faeces was performed for 6 days at the end of each period to determine the coefficient of total tract apparent digestibility (CTTAD). The CTTAD for DM, organic matter, neutral detergent fibre...
Gas and particle concentrations in horse stables with individual boxes as a function of the bedding material and the mucking regimen.
Journal of animal science    July 17, 2009   Volume 87, Issue 11 3805-3816 doi: 10.2527/jas.2008-1569
Fleming K, Hessel EF, Van den Weghe HF.The aim of this study was to compare different types of bedding and mucking regimens used in horse stables on the generation of airborne particulate matter <10 microm (PM10) and 3 biogenic gases (carbon dioxide, nitrous oxide, and especially ammonia). Three separate experiments were undertaken. The experiments were carried out in an enclosed stable (9.7 m long, 8.7 m wide, and 3.5 m high) that had 5 single boxes housing 4 horses. The measuring instruments were set up in the middle of one side of the stable. In Exp. 1, 3 types of bedding material (wheat straw, straw pellets, and wood shavings) ...
Exposure to inhalable dust, endotoxins, beta(1->3)-glucans, and airborne microorganisms in horse stables.
The Annals of occupational hygiene    June 26, 2009   Volume 53, Issue 6 595-603 doi: 10.1093/annhyg/mep040
Samadi S, Wouters IM, Houben R, Jamshidifard AR, Van Eerdenburg F, Heederik DJ.Workers in horse stables are likely exposed to high levels of organic dust. Organic dusts play a role in increased risk of inflammatory reactions and are associated with respiratory diseases. The aim of this study was to investigate dust, endotoxin, beta(1-->3)-glucan, and culturable microorganisms exposure levels in horse stables. Methods: Ambient (n = 38) and personal (n = 42) inhalable dust samples were collected using PAS-6 sampling heads. As a special measurement, we included sampling near the horses' heads. Samples were analyzed for endotoxin and beta(1-->3)-glucan by Limulus amebo...
Combustion of horse manure for heat production.
Bioresource technology    March 3, 2009   Volume 100, Issue 12 3121-3126 doi: 10.1016/j.biortech.2009.01.050
Lundgren J, Pettersson E.The main objectives of this paper have been to evaluate the use of horse manure and wood-shavings as a fuel for heat production and to provide sets of data on the chemical composition, ash characteristics and ash forming elements of the fuel. Another objective has been to investigate the possibility to use the ash as fertiliser by analysing the heavy metal and nutrient contents. The results showed that the fuel is well suited for combustion for heat production causing low emissions of products of incomplete combustion. The emissions of NO(x) were however high due to the high content of fuel bo...
[Phytomass utilization and deposition of feces by ungulates on steppe pastures of eastern Mongolia].
Izvestiia Akademii nauk. Seriia biologicheskaia    July 31, 2008   Issue 3 350-359 
Abaturov BD, Dmitriev IA, Jargalsaikhan L, Omarov KZ.The amount of phytomass removed by a complex of livestock (horses, cattle, sheep, and goats) and wild ungulates (Mongolian gazelle Procapra gutturosa Pall.) grazing in plain and mountain pastures of eastern Mongolia has been estimated by taking account of feces deposited by these animals. The results show that at an animal density of up to 30 head/km2, the total annual amount of feces reaches 140 kg/ha (dry weight), with the greater part (up to 90 kg/ha) being deposited by horses. The contribution of Mongolian gazelles in some pastures reaches 20-40 kg/ha per year. Decomposition of feces proce...
Dynamics of pruning waste and spent horse litter co-composting as determined by chemical parameters.
Bioresource technology    July 22, 2008   Volume 100, Issue 1 497-500 doi: 10.1016/j.biortech.2008.06.005
Benito M, Masaguer A, Moliner A, Hontoria C, Almorox J.Co-composting of pruning waste and horse manure was monitored by different parameters. A windrow composting pile, having the dimensions 2.5m (height) x 30m (length) was established. The maturation of pruning waste and horse manure compost was accompanied by a decline in NH(4)(+)-N concentration, water soluble C and an increase in NO(3)(-)-N content. Organic matter (OM) content during composting followed a first-order kinetic equation. This result was in agreement with the microbiological activity measured by the CO(2) respiration during the process. The correlation at a high level of probabili...
Exploitation of a natural pasture by wild horses: comparison between nutritive characteristics of the land and the nutrient requirements of the herds over a 2-year period.
Animal : an international journal of animal bioscience    March 1, 2008   Volume 2, Issue 3 410-418 doi: 10.1017/S1751731107001474
Miraglia N, Costantini M, Polidori M, Meineri G, Peiretti PG.In the Molise region (Italy), some autochthonous populations are still bred and, between them, some wild horses named 'Pentro horses.' The breeding area is a natural pasture. It is 2200 ha extended including a broad plane surrounded by wooden hills. The aim of this research was to determine the nutritional characteristics of this area over a 2-year period to improve the management of the herd and to define the stocking rate in relation to the forage production in terms of production and quality. The forage samples were collected over two successive years during the grazing period (May to Octob...
Biogas production with horse dung in solid-phase digestion systems.
Bioresource technology    March 26, 2007   Volume 99, Issue 5 1280-1292 doi: 10.1016/j.biortech.2007.02.008
Kusch S, Oechsner H, Jungbluth T.Experiments on methanogenesis from horse dung were conducted in laboratory-scale batch reactors in order to determine the substrate performance in a solid-phase digestion process, more specifically in terms of potential energy recovery and suitable process technology. Dung from a horse stable with straw bedding was used. The temperature was kept in the mesophilic range. In the percolation process (with process water sprinkled over the stacked biomass) a proportion of 10-20% of solid inoculum (pre-digested horse dung) was found to be suitable. Comparative experiments with both percolation and f...
Early onset airway obstruction in response to organic dust in the horse.
Journal of applied physiology (Bethesda, Md. : 1985)    December 7, 2006   Volume 102, Issue 3 1071-1077 doi: 10.1152/japplphysiol.00264.2006
Deaton CM, Deaton L, Jose-Cunilleras E, Vincent TL, Baird AW, Dacre K, Marlin DJ.Equine recurrent airway obstruction (RAO) has been used as a naturally occurring model of human asthma. However, it is unknown whether there is an early-phase response in RAO. The aim of this study was to determine whether exposure to organic dust induces immediate changes in lung function in RAO-affected horses, which could be mediated by airway mast cells. Six RAO-affected horses in remission and six control horses were challenged with hay-straw dust suspension by nebulization. Total respiratory resistance at 1 Hz, measured by forced oscillation, was increased from 0.62 +/- 0.09 cmH(2)O.l(-1...
Comparison of the antioxidant status in tracheal and bronchoalveolar epithelial lining fluids in recurrent airway obstruction.
Equine veterinary journal    September 22, 2006   Volume 38, Issue 5 417-422 doi: 10.2746/042516406778400556
Deaton CM, Marlin DJ, Deaton L, Smith NC, Harris PA, Schroter RC, Kelly FJ.Following a period of airway inflammation the clearance of inflammatory cells along the mucociliary escalator may impose a considerable oxidant load on the trachea. Objective: To determine the degree of oxidative stress in tracheal epithelial lining fluid (ELF) in comparison to that present in peripheral airways after an acute exposure to organic dust. Methods: Tracheal wash fluid and bronchoalveolar lavage fluid (BALF) were collected for cytology and antioxidant analyses from 6 recurrent airway obstruction (RAO)-affected horses and 6 healthy control horses before and after stabling on straw b...
A comparison of the effect of forage type and level of feeding on the digestibility and gastrointestinal mean retention time of dry forages given to cattle, sheep, ponies and donkeys.
The British journal of nutrition    January 31, 2006   Volume 95, Issue 1 88-98 doi: 10.1079/bjn20051617
Pearson RA, Archibald RF, Muirhead RH.Four cattle, sheep, ponies and donkeys were fed dehydrated lucerne, early-cut hay, later-cut hay or barley straw in a Latin square-based design for four periods of 35 d. In the first sub-period animals were fed the diets ad libitum (1-21 d) and in the second sub-period they were fed the same diet restricted to 0.75 of ad libitum intake (days 22-35). Measurements of forage intake, apparent digestibilities and gastrointestinal mean retention times (MRT) were made in the last 7 d of each sub-period. Differences between species in voluntary DM intake (VDMI; g/kg live weight (LW)(0.75) and g/LW) we...
Direct activation of gelatinase B (MMP-9) by hay dust suspension and different components of organic dust.
Veterinary immunology and immunopathology    September 21, 2005   Volume 109, Issue 3-4 289-295 doi: 10.1016/j.vetimm.2005.08.019
Simonen-Jokinen T, Maisi P, Tervahartiala T, McGorum B, Pirie S, Sorsa T.Matrix metalloproteinases (MMPs) are involved in tissue destruction in allergic airway diseases. We studied the ability of various allergenic substances to directly activate recombinant 92kDa proMMP-9. The substances included hay dust suspension (HDS) and its components (supernatant, particulate matter and wash fluid of particulate matter), storage mite extract and two Aspergillus fumigatus extracts. The allergen suspensions were incubated in vitro with proMMP-9. After incubation the conversion of proMMP-9 to 10kDa lower active forms were studied using gelatin zymography and Western immunoblot...
[Farmer’s lung disease caused by straw or hay? Case report].
Laeknabladid    September 13, 2005   Volume 91, Issue 7-8 587-589 
Gudmundsson G, Olafsson L, Nikulásson S, Jónsdóttir B.A young woman was admitted to Akranes Regional Hospital because of dyspnea, fatigue and fever. She was found to have bilateral pneumonia but etiology was not found. She was treated with antibiotics with good resolution and was discharged after eight days from the hospital. Four weeks later she noticed rapidly progressive dyspnea and was found to be hypoxemic, and to have restrictive spirometry and diffuse interstitial changes on chest radiography. Computerized tomography of the lungs showed diffuse ground glass changes. Transbronchial biopsies from the lungs showed numerous small granulomas. S...
Variety in dustiness and hygiene quality of peat bedding.
Annals of agricultural and environmental medicine : AAEM    July 21, 2005   Volume 12, Issue 1 53-59 
Airaksinen S, Heiskanen ML, Heinonen-Tanski H, Laitinen J, Laitinen S, Linnainmaa M, Rautiala S.Respiratory exposure to organic dust induces chronic pulmonary diseases both in farmers and horses. The aim of this study was to examine the variation of dustiness and hygiene quality of peat moss bedding. Materials studied were weakly decomposed sphagnum peat (A), weakly decomposed sphagnum peat warmed up in storage (> 30 degrees C) (B) and two more decomposed few-flowered sedge peats (C and D). The geometric mean of mesophilic fungi, thermotolerant fungi and thermophilic actinomycetes were determined from the material. Samples of inhalable dust and endotoxins were collected with IOM samplers...
Effects of hay intake and feeding sequence on variables in faeces and faecal water (dry matter, pH value, organic acids, ammonia, buffering capacity) of horses.
Journal of animal physiology and animal nutrition    February 1, 2004   Volume 88, Issue 1-2 7-19 doi: 10.1111/j.1439-0396.2004.00447.x
Zeyner A, Geissler C, Dittrich A.To investigate effects of hay intake and feeding sequence on indicators of the microbial activity within the hindgut, six horses were fed 1.00 kg oats plus 0.50, 0.67, 0.83 or 1.00 kg hay/100 kg body weight (BW) x day, each for 14 days. Oats was offered either 30 min prior to hay (OA) or in the reversed sequence (HA) in a 2 x 8-week crossover design. Because typically exercised horses should be subjected to the study, faeces was used as substrate. Faecal dry matter (DM), the faecal waters' short-chain fatty acids (SCFA, in mmol/1) and molar percentages (mol%) of propionate and iso-butyrate wer...
Fourier transform infrared microspectroscopic investigation of the organic and mineral constituents of peritubular dentin: a horse study.
Calcified tissue international    July 23, 2002   Volume 71, Issue 2 179-185 doi: 10.1007/s00223-001-2108-5
Magne D, Guicheux J, Weiss P, Pilet P, Daculsi G.Peritubular dentin (PTD) is a relatively dense mineralized tissue surrounding tooth dentin tubules, whose composition and mode of formation are still unclear. Fourier transform infrared microspectroscopic studies of the organic and mineral components of the highly developed horse PTD indicate that the peritubular matrix is less abundant than the intertubular matrix but is also mainly composed of collagen, which is more hydrated. These data suggest that most of the crystals are located outside the collagen fibrils and probably not associated with protein components. The crystals in PTD have nea...