Wool Growth Research Articles

Effect of Long-Term Supplementation of Selenium on Wool Production and Quality in Sheep

Selenium is an essential trace element for wool growth and its characteristics especially during the exposure of animals to stress. Twenty adult, dry, non-pregnant ewes aged 3-4 years old ranging from 45 to 50 kg body weight ,were chosen for the trial and divided into two equal groups, each of 10 ewes. The ewes were fed on a formed diet according to National Research Council (1985). The control group was fed on the formed diet without any supplements. The treated group was fed on the same diet plus 0.33gm selenoprotein (0.7 available selenium)The trial lasted for one year. The grease Fleece Weight(GFW), Clean Fleece Weight(CFW), FibreDiametre(FD), Staple Length(STL), Fibre Length(FL), Staple Strength(SST), Elongation percentage(ELO%) and Glutathione Peroxidase enzyme(GPX) in the blood serum were measured to study the effect of long term supplementation of selenium on wool production and quality in sheep. GFW, CFW, STL and FL weren’t affected significantly. The FD in tip portion was affected significantly P≤ 0.5 by the addition of selenoproten to the diet of the ewes. There was a significant difference between treated and untreated group in the sulphur content of the tip. The GPX was significantly higher in the treated group compared to control one. No significant difference between treated and untreated group in SST and elongation percentage.Addition of selenium to the diet of dry – non pregnant ewes didn’t greatly affect wool production or quality in natural environmental conditions since there were no stresses on animals.

Identification and characterization of circRNAs in the skin during wool follicle development in Aohan fine wool sheep

BackgroundAohan fine wool sheep (AFWS) is a historically bred fine wool sheep, cultivated in China. The wool has excellent quality and good textile performance. Investigating the molecular mechanisms that regulate wool growth is important to improve wool quality and yield. Circular RNAs (circRNAs) are widely expressed non-coding RNAs that can act as competitive endogenous RNAs (ceRNAs) to bind to miRNAs. Although circRNAs have been studied in many fields, research on their activity in sheep wool follicles is limited. To understand the regulation of circRNAs in the growth of fine wool in sheep, we used RNA-Seq to identify circRNAs in sheep shoulder skin samples at three developmental stages: embryonic day 90 (E90d), embryonic day 120 (E120d), and at birth (Birth).ResultsWe identified 8753 circRNAs and found that 918 were differentially-expressed. We then analyzed the classification and characteristic of the circRNAs in sheep shoulder skin. Using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), we identified the source genes of circRNAs, which were mainly enriched in cellular component organization, regulation of primary metabolic processes, tight junctions, and the cGMP-PKG and AMPK signaling pathways. In addition, we predicted interactions between 17 circRNAs and eight miRNAs, using miRanda software. Based on the significant pathways, we speculate that circ_0005720, circ_0001754, circ_0008036, circ_0004032, circ_0005174, circ_0005519, and circ_0007826 might play an important role in regulating wool follicle growth in AFWS. Seven circRNAs were randomly selected to validate the RNA-Seq results, using qRT-PCR.ConclusionOur results provide more information about circRNAs regulation of wool follicle development in AFWS, and establish a solid foundation for future research.

Effect of the Shearing Date on Wool Growth on Native Pasture in Merino Sheep

Effect of the Shearing Date on Wool Growth on Native Pasture in Merino Sheep

Seasonal variation of wool fibre length in Karagouniko and Chios sheep in relation to meteorological factors

Karagouniko and Chios sheep breeds present a lot of advantages on the implementation of sheep farming in Greece, a country with diverse relief resulting in a microclimatic variety, but nothing is known about the impact of season, as the outcome of important meteorological variables, on the fibre length growth (FLG) of the aforementioned breeds. Thus, the effect of season (Winter, Spring, Summer, Autumn) on the FLG of these breeds (by using analysis of variance) was studied in the Artificial Insemination Center of Karditsa (39021΄18΄΄N, 21054΄19΄΄E), Periphery of Thessaly, Greece, combined with a correlation analysis between FLG of each examined sheep breed and each of the studied meteorological variables, air temperature (AIRT), relative humidity (RH), sunshine (SUNS) and rainfall (R) for a two-year period. It was found that the FLG of Karagouniko sheep was significantly higher than the respective growth of Chios sheep, for each examined season, while the descending order of seasonal FLG for both breeds was Winter>Spring>Autumn>Summer. Fibre length growth of Karagouniko and Chios breeds correlated negatively with AIRT and SUNS and positively with RH, implying a better FLG in cooler, more overcast and wetter time periods. Our study adds new knowledge concerning the effect of season, and particularly, the effect of the aforementioned meteorological variables on the wool growth of two considerable sheep breeds in Greece, Karagouniko and Chios, opening up new horizons for their exploitation.

Effects of the dietary digestible fiber-to-starch ratio on pellet quality, growth and cecal microbiota of Angora rabbits.

ObjectiveSubstituting starch with digestible fiber (dF) can improve digestive health of rabbits and reduce costs. Therefore, it is necessary to develop a criterion for dF and starch supply. Effects of the dietary dF-to-starch ratio on pellet quality, growth and cecal microbiota of Angora rabbits were evaluated.MethodsFive isoenergetic and isoproteic diets with increasing dF/starch ratios (0.59, 0.66, 0.71, 1.05, and 1.44) were formulated. A total of 120 Angora rabbits with an average live weight of 2.19 kg were randomly divided into five groups with four replicates. At the end of 40 day feeding trial, cecal digesta were collected to analyse microbiota.ResultsThe results showed that the dF/starch ratio had linear effects on pellet variables (p< 0.01). When the dF/starch ratio was 1.44, the pellets had the lowest powder and highest durability. The dF/starch ratio had unfavorable linear effects on growth variables (p<0.001). When analyzed by quadratic regression, the optimal dF/starch ratios for average weight gain and feed/gain were 0.59 and 0.74, respectively. There were differences in wool yield, fiber length and fiber diameter caused by the dF/starch ratio (p<0.05), and the dF/starch ratios that ranged from 0.66 to 1.06 were appropriate for good results. The cecal microbiota operational taxonomic unit (OTU) number index in the 1.05 dF/starch treatment was higher than that in the 0.66 and 0.71 dF/starch treatments. The higher dF/starch ratio resulted in a higher cecal microbiota OTU number index (p<0.05). The proportion of Ruminococcus in the 0.71 dF/starch treatment was higher than that in the 0.59 dF/starch treatment (p<0.05)ConclusionThe most suitable dF/starch ratio for feed pellet quality is 1.44, and for rabbit growth the optimal range of ratios is from 0.59 to 0.74. With combination of the wool growth, output cost, and cecal microbiota, we suggest that a dietary dF/starch ratio ranging from 0.74 to 1.06 is optimal.

Effect of selenium supplementation of the diet on wool production during pregnancy in Ossimi ewes

A trial was carried out on thirty pregnant Ossimi ewes aged 3-4 years, belonging to the Animal Production Research Station at Sids, with live weight ranging between 45 to 50 kg. The animals were divided at randomly into 3 groups of 10 ewes each with almost equal mean live body weight. Animals were given maintenance and production diets according to their average body weight (NRC 1988). Concentrate feed mixture composed of 22% decorated cotton seed cake, 20% molasses, 44% wheat bran, 10% yellow maize, 2.5% ground limestone and 1.5% common salt. Water was provided ad-libitum during the whole experimental period with clover hay and rice straw. The trial started 1st January and ended 1st June 2018 (5 mo. /wool growth) and included 3 groups; Control group; received the basal diet only without any supplements, the first group; was given the basal diet plus 0.23 gm selenoprotein / kg dry matter/ head/day (0.5mg available selenium), the second group; was given the basal diet plus 0.33 gm selenoprotein / kg DM /head /day (0.7mg available selenium). The trial included two periods, the first three months of pregnancy and the last two months of pregnancy. The aim of this study was to study the effect of adding selenium to the diet of pregnant Ossimi ewes on wool growth. Physical and mechanical wool properties were assessed besides estimation of Glutathione peroxidase (GPX) enzyme activity. Results showed that during the first 3 months of pregnancy, there was significant difference (P≤0.05) among groups in FD, SST, ELO % and GPX enzyme activity, while there was no significant difference in STL. But in the last two months of pregnancy there was significant difference (P≤0.05) among groups in STL, FD, SST, ELO % and GPX enzyme activity.

Sheep wool cortisol as a retrospective measure of long-term HPA axis activity and its links to body mass

Hair cortisol analysis has been suggested as a powerful retrospective measure of long-term hypothalamic-pituitary-adrenal (HPA) axis activity in numerous mammal species. In contrast, research evaluating the use of wool as a marker of long-term HPA axis activity is still scarce, and wool differs from hair in a number of ways. Here, we assess repeatability and differences in wool cortisol concentrations (WCCs) across (i) the wool shaft, (ii) two body locations, and (iii) time, in 33 barren Welsh mountain ewes (Ovis aries). We also (iv) investigated effects of grazing-related changes in body mass on WCCs and (v) assessed effects of the washing procedure during sample preparation on WCCs. Cortisol concentrations were repeatable but differed significantly across the wool shaft indicating that, provided wool growth rate is known, a single sample per individual could be used as a retrospective cortisol “timeline.” WCCs were significantly higher in shoulder than in back samples, and no correlation between these two body locations was found, highlighting the importance of sampling from the same body location for repeated measures. An increase in body mass during grazing corresponded with a decrease in WCCs, which was significantly negatively correlated with body mass (and positively with age), suggesting that WCCs can be used as a marker of body condition and nutritional status in sheep. Interestingly, we found higher WCCs in washed compared with unwashed samples and discuss implications of this finding for future work. Overall, our study revealed significant within- and between-individual differences in WCCs and highlights a number of advantages but also methodological considerations of using WCCs as a retrospective measure of long-term HPA axis activity in sheep.

Body and wool growth of lambs grazing on native pastures can be improved with energy and protein supplementation

In a completely randomized experimental design with two replicates, the impact of iso-energetic supplements with different protein levels on body and wool growth was studied in eighty crossbreed (Merino Dohne × Corriedale) castrated male lambs (24.5 ± 4.4 kg of body weight, BW, 4 months of age) in summer (103 days) for three years. Animals were randomly allotted to four treatments (n = 20). All lambs grazed native pastures (NP) and animals in three treatments were daily supplemented (2% BW) with an iso-energetic supplement of different CP levels: control (CON, non supplemented), 12% CP (12CP), 16% CP (16CP) and 20% CP (20CP). Supplemented lambs had higher final BW (36.0, 36.4 and 37.7 kg for 12, 16 and 20CP, respectively) than CON lambs (28.9 kg) (P < 0.05). Among supplemented lambs, the 12CP group had the lowest BW (P < 0.05), without differences between 16CP and 20CP. Supplemented lambs had greater body-weight gain, body condition score, rib eye area and fat thickness than CON lambs (P < 0.05). Wool growth was 40% greater in supplemented lambs compared to CON lambs (P < 0.05), while 20CP animals had the greatest growth. Iso-energetic supplementation with different CP (12, 16 and 20%) levels improved body and wool growth of lambs grazing NP compared to non-supplemented lambs in summer after weaning. Wool growth was greatest when 20% CP supplement was used.

Transcriptomic analysis reveals differentially expressed genes associated with wool length in rabbit

Rabbit fur characteristics are primarily genetically determined traits. We used Illumina high-throughput sequencing technology to assess gene expression in the skin tissues of rabbits derived from a cross between Wanxi Angora rabbits and Rex rabbits, which exhibit differential characteristics of short and long wool respectively, to investigate molecular mechanisms related to wool length determination. To identify key regulatory genes involved in rabbit wool length, genes that were differentially expressed between the long- and short-wool rabbits based on a P-value < 0.05 and log2 |fold change|>1 were characterized. A total of 798 genes were up-regulated and 523 were down-regulated in the long-wool group compared to expression levels in the short-wool group, and these genes were annotated with GO terms and KEGG pathways, revealing wool-development-related biological functions. The Wnt, Hedgehog and TGF-β signaling pathways, which are related to cell proliferation, fibroblast proliferation and hair follicle regulation respectively, were identified. The expression levels of eight genes were validated by RT-qPCR. In addition, an interaction network was constructed to show the regulatory relationships among the differentially expressed genes. In this study, we found that FGF5, WNT5A, BMP4 and BMP7 showed significant differential expression between the two groups. These transcriptomic profiling results provide comprehensive gene expression information for improving understanding of the molecular mechanisms involved in the growth and development of rabbit wool.

Machine learning approaches for early prediction of adult wool growth and quality in Australian Merino sheep

Wool production and its quality play important roles in determining the total income received by Australian sheep producers. Enabling accurate and early prediction of wool production and quality traits for individual and groups of sheep can provide useful information assisting on-farm management decision-making. Robustness and high performance of modern prediction methods, namely Machine Learning (ML) algorithms, make them suitable for this purpose. In this research, flock specific environmental data and phenotypic information of yearling lambs were combined to identify the most effective algorithm to predict adult Greasy Fleece Weight (aGFW), adult Clean Fleece Weight (aCFW), adult Fibre Diameter (aFD), adult Staple Length (aSL), and adult Staple Strength (aSS). Algorithms were evaluated and compared in terms of prediction error, the correlation between predicted and actual phenotype in a test set, and for uncertainty in prediction.Artificial Neural Networks (NN), Model Tree (MT) and Bagging (BG) were used to carry out these predictions and their performance was compared with Linear Regression (LR) as the gold standard of prediction. The NN method had the poorest performance in all five traits. MT and BG had very similar performance and for a number of practical reasons, our method of choice was MT for early prediction of adult wool traits. The correlation coefficients of MT predictions were 0.93, 0.90, 0.94, 0.81 and 0.59 with Mean Absolute Error of 0.48 kg, 0.41 kg, 0.92 µm, 6.91 mm and 6.82 N/ktex, for predicting aGFW, aCFW, aFD, aSL, and aSS respectively.

Methane emissions and productivity of defaunated and refaunated sheep while grazing

Rumen protozoa produce hydrogen, which can be utilised by methanogens to produce enteric methane (CH4) that is a loss of digested energy and has an adverse environmental impact as a greenhouse gas. The aim of this study was to examine the effect of the absence of rumen protozoa on pasture intake, ruminal fermentation and enteric CH4 production and performance of grazing sheep. An incomplete crossover experiment was conducted with eleven crossbred ewes (6 without [defaunated] and 5 with protozoa [refaunated]) on 2 × 2 ha pastures with daily CH4 production (DMP) being measured by GreenFeed Emission Monitoring (GEM) units. Grazing defaunated sheep exhibited a lower concentration of rumen ammonia (P = 0.01), but similar concentrations of total rumen volatile fatty acids compared to refaunated sheep (P > 0.05). The molar proportion of acetate was decreased and butyrate proportion was increased by defaunation, while the proportion of propionate was unchanged. Estimated pasture intake was not different between defaunated and refaunated sheep (P > 0.05). Defaunated sheep tended to have a higher total dry matter intake (tDMI; P = 0.06), being the sum of pasture intake and pellet supplement intake. There was a tendency towards a lower CH4 yield (g CH4/kg tDMI; P = 0.07) in defaunated sheep, but no differences in average daily gain or wool growth occurred due to defaunation.

Study of Vasodilating and Regenerative Effect of the Gel with Nettle Juice intended for Telogen Effluvium Treatment

Telogen effluvium remains the most common diffuse hair loss in women which influences the quality of their life. Stinging nettle leaves and steams contain a wide range of biologically active substances which stimulate the metabolism and trophic processes in hair follicle cells. The purpose of the research was to study the vasodilating effect and follicle-stimulating activity of the gel with nettle juice in rats under conditions of wool shedding induced by orally administered boric acid. Thus, conducted pharmacological studies indicated that the gel in comparison with the untreated animals accelerated the wool growth in rats, improved its quality by increasing the weight and reducing the percentage of dystrophic hairs. Histological studies confirmed that cutaneous application of the gel significantly dilated the vessels in the dermis reticular layer. The intensification of blood supply was confirmed by an increase in the number of mast cells and their active degranulation. Strengthening of blood circulation caused the increase of the hair follicle quantity in the active anagen phase.

Prediction of fleece insulation after shearing and its impact on maintenance energy requirements of Romney sheep

Calculation of the maintenance metabolisable energy (ME) requirements should include the additional ME required to counteract heat loss in cold conditions if ambient temperatures occur below the lower critical temperature (LCT) of sheep. This correction requires an estimate of the fleece length of sheep during the year. Equations are presented to estimate the monthly fleece length of Romneys assuming different patterns of seasonality of wool growth, month of shearing and total fleece length. These lengths are discussed in the context of predicted levels of fleece insulation, which in turn influence sheep energy requirements under New Zealand climatic conditions. Predicted fleece insulation varied from 1 to 8°Cm2d/MJ in different months. The additional maintenance ME requirements of ewes are predicted for each month following shearing for different months of shearing. An example calculation resulted in an estimated additional 30% of ME being required when the average daily ambient temperature in the month of shearing was 5°C below the LCT.

The impact of supplementation withRhagodia preissiiandAtriplex nummulariaon wool production, mineral balance and enteric methane emissions of Merino sheep

The Australian perennial shrubs, oldman saltbush (Atriplex nummularia) and rhagodia (Rhagodia preissii), can complement the diets of sheep grazing moderate-quality cereal residues. We compared liveweight change, organic matter digestibility, nitrogen and mineral balance, wool growth and methane emissions of Merino wethers offered oaten hay (OMD 622 g kg−1 DM; N 9.74 g kg−1 DM) with and without shrub biomass (substituted at 25% of OM). Diets were fed at restricted levels for 1 month. Substituting hay with shrub biomass significantly decreased liveweight loss, increased clean wool growth and increased apparent absorption of phosphorus compared to the hay alone. Substitution of hay with both saltbush and rhagodia led to over 23% greater clean wool growth. Nitrogen balance and apparent digestion of organic matter, calcium and magnesium did not vary significantly between animals on the diets. Wethers on the rhagodia and hay diets had similar enteric methane emissions, while animals offered the saltbush diet had significantly higher emissions (L/OM intake). When methane is expressed in terms of wool growth, animals on the rhagodia diet produced 26% less methane for every gram of wool.

Microbial population analysis of the midgut of Melophagus ovinus via high-throughput sequencing

BackgroundMelophagus ovinus, one of the most common haematophagous ectoparasites of sheep, can cause anaemia and reductions in weight gain, wool growth and hide value. However, no information is available about the microfloral structure of the midgut of this ectoparasite. In the present study, we investigated the microbial community structure of the midgut contents of fully engorged female and male M. ovinus using Illumina HiSeq.ResultsThe phylum showing the highest abundance was Proteobacteria (99.9%). The dominant bacterial genera in females and males were Bartonella, Arsenophonus and Wolbachia. Some less abundant bacterial genera were also detected, including Enterobacter, Acinetobacter, Halomonas, Shewanella, Bacillus and Staphylococcus.ConclusionsBartonella, Arsenophonus and Wolbachia were the dominant bacterial genera in the midgut of female and male M. ovinus. Although detected, Enterobacter, Acinetobacter, Halomonas, Shewanella, Bacillus and Staphylococcus showed low abundances. Importantly, this is the first report of the presence of Arsenophonus, Wolbachia, Enterobacter, Halomonas, Shewanella, Bacillus and Staphylococcus in the midgut of M. ovinus.

CRISPR/Cas9-mediated loss of FGF5 function increases wool staple length in sheep.

Fibroblast growth factor 5 (FGF5) regulates hair length in humans and a variety of other animals. To investigate whether FGF5 has similar effects in sheep, we used clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated 9 (Cas9) to generate loss-of-function mutations with the FGF5 gene in Chinese Merino sheep. A total of 16 lambs were identified with genetic mutations within the targeting locus: 13 lambs had biallelic modifications and three lambs had monoallelic modifications. Characterization of the modifications revealed that 13 were frameshift mutations that led to premature termination, whereas the other three were in-frame deletions. Thus, CRISPR/Cas9 efficiently generated loss-of-function mutations in the sheep FGF5 gene. We then investigated the effect of loss of FGF5 function on wool traits in 12 lambs and found that wool staple length and stretched length of genetically modified (GM) yearling sheep were significantly longer compared with that of wild-type (WT) control animals. The greasy fleece weight of GM yearling sheep was also significantly greater compared with that of WT sheep. Moreover, the mean fiber diameter in GM sheep showed no significant difference compared with WT sheep, suggesting that the increase in greasy fleece weight was likely attributed to the increase in wool length. The results of this study suggest that CRISPR/Cas9-mediated loss of FGF5 activity could promote wool growth and, consequently, increase wool length and yield.

Ectopic expression of FGF5s induces wool growth in Chinese merino sheep

Fibroblast growth factor 5 (FGF5) has been recognized as an inhibitor to cease animal hair growth, while in contrary, FGF5 short alternative transcript (FGF5s) can induce hair growth by antagonizing FGF5 function. To investigate the role of FGF5s in wool growth in Chinese Merino sheep, we generated transgenic sheep of ectopic expression of FGF5s by injection of recombinant lentivirus into zygote. Totally 20 transgenic sheep were obtained and 12 were alive after birth. Characterization of the transgene revealed that the transgenic sheep showed variety of integrant, ranged from 2 to 11 copies of transgene. The ectopic expression of FGF5s was observed in all transgenic sheep. Further study on the effect of ectopic expression of FGF5s revealed that the wool length of transgenic sheep were significantly longer than that of non-transgenic control, with 9.17cm of transgenic lambs versus 7.58cm of control animals. Notably, besides the increase of wool length, the yearling greasy fleece weight was also concordantly greater than that of wild-type (p<0.01), with 3.22kg of transgenic sheep versus 2.17kg of control lambs (p<0.01) in average. Our results suggested that overexpression of FGF5s could stimulate wool growth and resulted in increase of wool length and greasy wool weight.

Seasonal pattern of skin follicles activity and fibre growth in grazing fat-tailed Kermani sheep in the South of Iran

Photoperiod is known to be important in regulating the pattern of wool growth in sheep. The aim of this study was to investigate the effect of natural changes in photoperiod on live weight, skin follicle activity and fiber characteristics of grazing Kermani sheep in the south of Iran, Jiroft (28° 40′ N and 57° 44′ E, elevation 650m). Ten male and 10 female Kermani sheep with initial live weights of 31.9±0.8 and 30.7±0.9kg (mean±s.e.) respectively, were used in a 365day study. Percentage of active primary (PAP) and percentage of active secondary (PAS) follicles, ratio of secondary to primary follicles (S/P) and follicle density (FD) were measured in skin samples, taken from the right mid-side of the animals at monthly intervals. Greasy and clean wool growth rates and fibre diameter were determined from patch samples (10cm×10cm) harvested at the end of every month. The value for PAP was greatest (p<0.05) in summer and spring and lowest (p<0.05) in winter (98.2±0.8, 84.1±0.9, 75.6±0.8 and 97.0±1.1% for summer, autumn, winter and spring, respectively); seasonal differences in PAS were similar (99.3±0.8, 88.5±0.7, 82.9±0.8 and 98.9±0.7% for summer, autumn, winter and spring, respectively). Clean wool growth rate was greatest (p<0.001) in summer and spring, and lowest (p<0.001) in winter (0.7±0.03, 0.4±0.04, 0.3±0.01 and 0.7±0.05mg/cm2/day for summer, autumn, winter and spring, respectively). Fibre diameter was greatest in spring (34.8±0.3μm) and lowest in winter (29.1±0.2μm). The values for wool growth rates and fibre diameter were greater (p<0.05) in male rather than those observed in female sheep. Fibre and skin follicle characteristics were not affected by a season×sex interaction. These results demonstrated that there is a seasonal pattern in fibre follicles activity and wool growth in grazing Kermani sheep.

Thorburn Brailsford Robertson: Brilliant Scientist, Innovator and Australia’s First Professor of Biochemistry

Thorburn Brailsford Robertson (1884–1930) was educated in Adelaide and held appointments at the University of California, Berkeley (where he completed his PhD in 1907), and the University of Toronto before taking up his appointment at Adelaide in 1919 as Australia's first Professor of Biochemistry. In his research on the biochemical basis of growth and senescence he discovered in pituitary tissue a growth factor he called Tethelin. He made important contributions to the fabric and collegiality of the University of Adelaide. Amongst his many scientific contributions he was the first person outside Canada to prepare insulin, a project taken up by the Commonwealth Serum Laboratories. In 1927 he became the first Chief of the Division of Animal Nutrition in the Council for Scientific and Industrial Research, for whom he investigated sheep nutrition and wool growth.

Brief communication: Extended chronology of the Cordón Caulle volcanic eruption beyond 2011 reveals toxic impacts

Abstract. Aside of immediate impacts, the 2011 Puyehue–Cordón Caulle volcano (PCC) eruption also caused persisting chemical impacts. By 2012, toxicity resulted in overt dental fluorosis in deer, with bone fluoride increasing &gt; 38-fold to 5175 ppm. Sheep, horses and cattle also succumbed to fluorosis. Due to eolian redeposition of tephra, exposure of ruminants continued, bone fluoride reached 10 396 ppm, and by 2014 skeletal fluorosis was found. Nonskeletal fluorosis resulted in reduced wool growth and major losses among periparturient cattle. Peculiarities of digestive processes make ruminants susceptible to fluoride-containing tephra, which averaged 548 ppm from PCC. Moreover, recent volcanic eruptions causing fluorosis could be aggravated by local iodine deficiency, which increases the incidence and harshness of fluorosis, and deficiency of selenium, which, among other things, also results in secondary deficiency of iodine. Notwithstanding, several measures are available to livestock producers to minimize chemical impacts of fluoride.