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Background: Osteochondrosis (OC), simply defined as a failure of endochondral ossification, is a complex disease with both genetic and environmental risk factors that is commonly diagnosed in young horses, as well as other domestic species. Although up to 50 % of the risk for developing OC is reportedly inherited, specific genes and alleles underlying risk are thus far completely unknown. Regions of the genome identified as associated with OC vary across studies in different populations of horses. In this study, we used a cohort of Standardbred horses from the U.S. (n = 182) specifically selected for a shared early environment (to reduce confounding factors) to identify regions of the genome associated with tarsal OC. Subsequently, putative risk variants within these regions were evaluated in both the discovery population and an independently sampled validation population of Norwegian Standardbreds (n = 139) with tarsal OC. Results: After genome-wide association analysis of imputed data with information from >200,000 single nucleotide polymorphisms, two regions on equine chromosome 14 were associated with OC in the discovery cohort. Variant discovery in these and 30 additional regions of interest (including 11 from other published studies) was performed via whole-genome sequencing. 240 putative risk variants from 10 chromosomes were subsequently genotyped in both the discovery and validation cohorts. After correction for population structure, gait (trot or pace) and sex, the variants most highly associated with OC status in both populations were located within the chromosome 14 regions of association. Conclusions: The association of putative risk alleles from within the same regions with disease status in two independent populations of Standardbreds suggest that these are true risk loci in this breed, although populationspecific risk factors may still exist. Evaluation of these loci in other populations will help determine if they are specific to the Standardbred breed, or to tarsal OC or are universal risk loci for OC. Further work is needed to identify the specific variants underlying OC risk within these loci. This is the first step towards the long-term goal of constructing a genetic risk model for OC that allows for genetic testing and quantification of risk in individuals. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect on digestibility of forages using a daisy jar system with inoculum from steers supplemented with the yeast fermentation product Saccharomyces cerevisiae. Forages tested included ryegrass, wheat, orchard grass, alfalfa, and sorghum sudan hays. Samples were ground through a 1mm screen, placed in Ankom F57 bags, and run in triplicate to increase statistical significance. Two ruminally cannulated jersey steers were used in a switchback design. Animals were housed in a dry lot pen. The study consisted of 2 three-week periods, 2-week standardization followed by a 1-week test period. Diets offered for period 1 were steer A = 100% alfalfa hay w/o yeast product and steer B = 100% wheat hay w/o yeast product. Diets offered for period 2 were steer A =100% alfalfa hay +15g/h/d yeast product and steer B =100% wheat hay +15g/h/d yeast product. During the test week, rumen fluid contents were collected from each donor via rumen cannula approximately 4 h after feeding and taken to the lab to be composited. The samples were incubated for 0 h, 24 h, 48 h, 72 h, and 96 h. At the end of the incubation period bags were collected and cold shocked to stop microbial digestion. Samples were dried at 55oC and stored for later analysis. Model included trt (+/-yeast), forage, hr, and interactions forage*hr and forage*trt. No significant differences were observed (P = 0.38) on DM digestibility or NDF digestibility (P = 0.76) with the supplementation of yeast fermentation product. Forage*Trt was significant (P = 0.03 DMdig, P = 0.02 NDFdig). Implications of this study are the inclusion of a Saccharomyces cerevisiae fermentation product at a rate of 15g/h/d may not impact overall forage NDF or DM digestibility but may impact types of forage differently in an in vitro system using composited inoculum from donors on a forage diet. [ABSTRACT FROM AUTHOR]

Colloids have been successfully used in a number of species to improve sperm populations for IVF and for cryopreservation The usefulness of Single Layer Centrifugation (SLC) for freezing dromedary camel spermatozoa in two different extenders was evaluated by examining the motility, viability, acrosome status, DNA integrity, and ability of cryopreserved sperm to penetrate oocytes in vitro in a heterologus IVF system. Two ejaculates from each of five males were divided into four aliquots: two were processed by SLC (selected) while two were centrifuged without colloid (control). Pellets were cryopreserved in Green Buffer or INRA-96® containing 3% glycerol and evaluated at 0 and 1 h post thawed. The SLC improved post-thaw total and progressive motility at 0 (both P  < 0.0001) and 1 ( P  < 0.001; P  < 0.01, respectively) h, and STR (both P  < 0.05) and BCF (both P  < 0.001) at 0 h. Sperm viability and acrosome integrity (both P  < 0.001) were improved at both time points. Sperm frozen in Green Buffer had greater total and progressive motilities at 0 (both P  < 0.001) and 1 (both P  < 0.001) h than INRA-96® samples. Spermatozoa in Green Buffer also had a greater VAP, VCL and VSL at 0 h and improved viability and acrosome integrity at 0 h ( P  < 0.05; P  = 0.001, respectively) and 1 h ( P  < 0.05; P  < 0.001, respectively). Viability of SLC spermatozoa was improved in Green Buffer at 1 h ( P  < 0.05). Oocyte penetration ( P  < 0.05) and pronuclear formation ( P  < 0.01) were greater with SLC-selected spermatozoa than non-selected spermatozoa, regardless of extender. No difference was observed between treatments or extenders in the mean number of spermatozoa per oocyte penetrated. The SLC spermatozoa had less ( P  < 0.01) DNA fragmentation compared to controls. The DNA fragmentation was moderately and negatively correlated with penetration ( r  = −0.4162; P  = 0.02) and pronuclear formation ( r  = −0.3390; P  < 0.01). In conclusion, colloid centrifugation of spermatozoa and cryopreservation in Green Buffer improves post thaw motility variables and IVF performance of dromedary camel spermatozoa. [ABSTRACT FROM AUTHOR]

Treatment of clinical laminitis usually fails to prevent some degree of persistent disability; thus, intervention should aim at avoiding risk factors and preventing the disease. Efficiency of intervention would be improved by identifying predisposed horses and ponies. A herd of 160 healthy ponies included 54 previously laminitic (PL) and 106 never laminitic (NL). Pedigree analysis was consistent with dominant inheritance partially suppressed in males. Blood analysis revealed higher plasma concentrations of insulin and triglycerides but not cortisol, glucose, or free fatty acids in the PL group. Proxies for insulin sensitivity and β-cell responsiveness, which were calculated from plasma insulin and glucose, indicated compensated insulin resistance in the PL group. A prelaminitic metabolic syndrome (PLMS) was derived statistically to have cut-off points for the 2 proxies, hypertriglyceridemia, and body condition score. It had a total predictive power of 78%. It identified 62 ponies with PLMS, and 98 as PLMS-free. Two months later, pasture starch concentration doubled, and 13 clinical cases of laminitis developed, 11 in the PLMS group and 2 in the PLMS-free group, giving an odds ratio of 10.4 (P = 0.0006). The PLMS can be used to identify predisposed ponies in need of special care; the efficiency of intervention would increase nearly 3-fold in the present case. It enables the design of new interventions suitable for testing. The PLMS also might influence market values. [ABSTRACT FROM AUTHOR]

Objective—To evaluate genetic and metabolic predispositions and nutritional risk factors for development of pasture-associated laminitis in ponies. Design—Observational cohort study. Animals—160 ponies. Procedures—A previous diagnosis of laminitis was used to differentiate 54 ponies (PL group) from 106 nonlaminitic ponies (NL group). Pedigree analysis was used to determine a mode of inheritance for ponies with a previous diagnosis of laminitis. In early March, ponies were weighed and scored for body condition and basal venous blood samples were obtained. Plasma was analyzed for glucose, insulin, triglycerides, nonesterified fatty acids, and cortisol concentrations. Basal proxies for insulin sensitivity (reciprocal of the square root of insulin [RISQ]) and insulin secretory response (modified insulin-to-glucose ratio [MIRG]) were calculated. Observations were repeated in May, when some ponies had signs of clinical laminitis. Results—A previous diagnosis of laminitis was consistent with the expected inheritance of a dominant major gene or genes with reduced penetrance. A prelaminitic metabolic profile was defined on the basis of body condition, plasma triglyceride concentration, RISQI, and MIRG. Meeting ≥ 3 of these criteria differentiated PL- from NL-group ponies with a total predictive power of 78%. Determination of prelaminitic metabolic syndrome in March predicted 11 of 13 cases of clinical laminitis observed in May when pasture starch concentration was high. Conclusions and Clinical Relevance—Prelaminitic metabolic syndrome in apparently healthy ponies is comparable to metabolic syndromes in humans and is the first such set of risk factors to be supported by data in equids. Prelaminitic metabolic syndrome identifies ponies requiring special management, such as avoiding high starch intake that exacerbates insulin resistance. [ABSTRACT FROM AUTHOR]

Enhanced microbial activity in the equine hindgut increases nutrient availability, reduces fecal waste, and adds value to low quality forages. The dietary supplement DigestaWell® Fiber (DF; fibrolytic cofactors: methionine and B vitamins), designed to increase microbial efficiency, has been shown to improve in-vitro digestibility of alfalfa and tall fescue forages after 48h incubation. The objective of this study was to determine if DF would improve in-vitro dry matter digestibility (DMD) and ADF digestibility (ADFD) of alfalfa and coastal bermudagrass hays incubated for 48h or 72h. Utilizing a crossover design, four mature Quarter Horse mares were fed 2% BW daily of alfalfa (AF; 32.8% NDF, 27.1% ADF) or coastal bermudagrass (CB; 63.2% NDF, 35.4% ADF) hay for 19d periods. DMD and ADFD were determined after 48h or 72h incubation with or without treatment (320mg/L DF) at 37.5°C in an ANKOM Daisy II incubator inoculated with 200g fresh feces. Forage samples were run in triplicate. Data were transformed to approximate normality, then analyzed using a repeated measures mixed model in SAS with main effects of forage, treatment, incubation time, and feeding period, and statistically significant interactions. Across incubation times, DMD was higher for AF than CB (P < 0.01; 49.4% vs 42.1%). Across forages, DMD was higher at 72h than at 48h incubation (P < 0.01; 47.5% vs 43.9%). DF improved DMD across forages at 48h (P = 0.03), but not at 72h (P = 0.47). Across incubation times, DF improved DMD of CB (P < 0.01), but not AF (P = 0.79). Additionally, across both forages and both incubation times, DF improved ADFD (P < 0.01). In conclusion, DF may improve microbial fermentation in the equine hindgut. Future research should investigate in-vivo effects of oral supplementation of DF on forage digestibility measures. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Kathadin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group's body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Katahdin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group's body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product. [ABSTRACT FROM AUTHOR]

Enhanced microbial activity in the equine hindgut increases nutrient availability, reduces fecal waste, and adds value to low quality forages. The dietary supplement DigestaWell® Fiber (DF; fibrolytic cofactors: methionine and B vitamins), designed to increase microbial efficiency, has been shown to improve in-vitro digestibility of alfalfa and tall fescue forages after 48-h incubation. The objective of this study was to determine if DF would improve in-vitro dry matter digestibility (DMD) and ADF digestibility (ADFD) of alfalfa and coastal bermudagrass hays incubated for 48h or 72h. Utilizing a crossover design, four mature Quarter Horse mares were fed 2% BW daily of alfalfa (AF; 32.8% NDF, 27.1% ADF) or coastal bermudagrass (CB; 63.2% NDF, 35.4% ADF) hay for 19-d periods. DMD and ADFD were determined after 48-h or 72-h incubation with or without treatment (320mg/L DF) at 37.5°C in an ANKOM Daisy II incubator inoculated with 200g fresh feces. Forage samples were run in triplicate. Data were transformed to approximate normality, then analyzed using a repeated measures mixed model in SAS with main effects of forage, treatment, incubation time, and feeding period, and statistically significant interactions. Across incubation times, DMD was higher for AF than CB (P < 0.01; 49.4% vs 42.1%). Across forages, DMD was higher at 72h than at 48h incubation (P < 0.01; 47.5% vs 43.9%). DF improved DMD across forages at 48h (P = 0.03), but not at 72h (P = 0.47). Across incubation times, DF improved DMD of CB (P < 0.01), but not AF (P = 0.79). Additionally, across both forages and both incubation times, DF improved ADFD (P < 0.01). In conclusion, DF may improve microbial fermentation in the equine hindgut. Future research should investigate in-vivo effects of oral supplementation of DF on forage digestibility measures. [ABSTRACT FROM AUTHOR]