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Ellen Roelfsema - One of the best experts on this subject based on the ideXlab platform.

  • Effect of long-term overfeeding of a high-energy diet on glucose tolerance in Shetland Pony mares.
    Journal of Veterinary Internal Medicine, 2020
    Co-Authors: Nicky M M D Fonseca, Marta De Ruijter-villani, Tom A.e. Stout, C Gibson, David A Van Doorn, Ellen Roelfsema
    Abstract:

    BACKGROUND Overfeeding is associated with obesity and insulin dysregulation (ID), which are both risk factors for equine metabolic syndrome. How chronic overfeeding affects development of these factors is poorly understood. OBJECTIVES To examine the influence of long-term high-energy diet provision on body condition and ID. ANIMALS Eleven Shetland Pony mares. METHODS In a 3-phase study, the high-energy group (n = 7) was fed 200% of net energy (NE) requirements (hay; concentrate: 36% sugar and starch, 13% fat) for 24 weeks, followed by 17 weeks hay-only feeding before resuming the high-energy diet (n = 4) for an additional 29 weeks. Mares were weighed weekly. Oral glucose tolerance tests were performed 3 to 4 times per dietary period. Results were compared with those of a control group (phase 1, n = 4; phases 2 and 3, n = 6) that received 100% NE requirements, using a general linear mixed model with post hoc Bonferroni testing. RESULTS The mean body weight of the high-energy group increased by 27% per high-energy feeding period. During both feeding periods, area under the curve (AUC) for plasma glucose concentration decreased (P 

  • effect of long term overfeeding of a high energy diet on glucose tolerance in Shetland Pony mares
    Journal of Veterinary Internal Medicine, 2020
    Co-Authors: Nicky M M D Fonseca, C Gibson, David A Van Doorn, Marta De Ruijtervillani, T A E Stout, Ellen Roelfsema
    Abstract:

    BACKGROUND Overfeeding is associated with obesity and insulin dysregulation (ID), which are both risk factors for equine metabolic syndrome. How chronic overfeeding affects development of these factors is poorly understood. OBJECTIVES To examine the influence of long-term high-energy diet provision on body condition and ID. ANIMALS Eleven Shetland Pony mares. METHODS In a 3-phase study, the high-energy group (n = 7) was fed 200% of net energy (NE) requirements (hay; concentrate: 36% sugar and starch, 13% fat) for 24 weeks, followed by 17 weeks hay-only feeding before resuming the high-energy diet (n = 4) for an additional 29 weeks. Mares were weighed weekly. Oral glucose tolerance tests were performed 3 to 4 times per dietary period. Results were compared with those of a control group (phase 1, n = 4; phases 2 and 3, n = 6) that received 100% NE requirements, using a general linear mixed model with post hoc Bonferroni testing. RESULTS The mean body weight of the high-energy group increased by 27% per high-energy feeding period. During both feeding periods, area under the curve (AUC) for plasma glucose concentration decreased (P < .01), whereas AUC for plasma insulin concentration increased. Mean basal plasma glucose concentration and peak plasma insulin concentrations were higher (P < .05) in the high-energy group than in the control group. CONCLUSION AND CLINICAL IMPORTANCE Feeding a high-energy diet to healthy nonobese Shetland Pony mares led to more efficient glucose metabolism within 5 weeks, followed by significant hyperinsulinemia and obesity. Hyperinsulinemic status was reversed during 17 weeks of hay-only feeding, regardless of body condition, but returned rapidly after restarting the high-energy diet.

  • Ultrasonographic measurements of localized fat accumulation in Shetland Pony mares fed a normal v. a high energy diet for 2 years.
    Animal, 2017
    Co-Authors: E. W. Siegers, David A. Van Doorn, Marta De Ruijter-villani, Tom A.e. Stout, Ellen Roelfsema
    Abstract:

    : Health risks associated with obesity are more likely a factor of the localization of fat excess, rather than of elevated BW per se. The aim of this randomized controlled clinical trial was to determine the effect of a long-term high energy diet on BW, fat accumulation and localization. Eight Shetland Pony mares, 3 to 7 years old, were randomly divided into a control and a high energy (HE) diet group fed either maintenance or double maintenance energy requirements (200% net energy (NE)) for two consecutive summers, with a low energy diet in the winter in between. Body condition score (BCS) did not differ between the groups at the onset of the study (control 5.6±0.75 v. HE 6.3±0.5). From 12 weeks after starting the diet, ultrasonography of five different locations (retroperitoneal, axillary, withers, intercostal and rump) for adipose deposition, BCS and BW were measured monthly during the period that ponies received different diets. Statistical analysis was performed using a linear mixed-effects model with post hoc Bonferroni testing. P values

  • ultrasonographic measurements of localized fat accumulation in Shetland Pony mares fed a normal v a high energy diet for 2 years
    Animal, 2017
    Co-Authors: E. W. Siegers, T A E Stout, M De Ruijtervillani, D A Van Doorn, Ellen Roelfsema
    Abstract:

    Health risks associated with obesity are more likely a factor of the localization of fat excess, rather than of elevated BW per se. The aim of this randomized controlled clinical trial was to determine the effect of a long-term high energy diet on BW, fat accumulation and localization. Eight Shetland Pony mares, 3 to 7 years old, were randomly divided into a control and a high energy (HE) diet group fed either maintenance or double maintenance energy requirements (200% net energy (NE)) for two consecutive summers, with a low energy diet in the winter in between. Body condition score (BCS) did not differ between the groups at the onset of the study (control 5.6±0.75 v. HE 6.3±0.5). From 12 weeks after starting the diet, ultrasonography of five different locations (retroperitoneal, axillary, withers, intercostal and rump) for adipose deposition, BCS and BW were measured monthly during the period that ponies received different diets. Statistical analysis was performed using a linear mixed-effects model with post hoc Bonferroni testing. P values <0.05 were considered significant. At week 12 after the onset of the diet, fat thickness in the HE group was significantly greater than in the control group. During the monitoring period, the HE group showed a significant increase in mean (±SE) BW (+52%, 265±13.94kg) and BCS (+70%; to 9.0±0.4), while the control group was unchanged (BW 160±13.98 kg; BCS 3.8±0.4). At all locations, the fat depth in the HE group increased significantly, with the highest increase noted for retroperitoneal deposits. The conclusions were that a 200% NE diet induced subcutaneous and retroperitoneal fat accumulation, with the greatest increase in intra-abdominal deposits. The moderate increase of the subcutaneous fat depth followed by a plateau phase suggests the existence of a limit of adipose tissue expandability, as in man.

Ottmar Distl - One of the best experts on this subject based on the ideXlab platform.

  • Genome data uncover four synergistic key regulators for extremely small body size in horses
    BMC Genomics, 2018
    Co-Authors: Julia Metzger, Janina Rau, Fanny Naccache, Gabriella Lindgren, Laura Bas Conn, Ottmar Distl
    Abstract:

    Background Miniature size in horses represents an extreme reduction of withers height that originated after domestication. In some breeds, it is a highly desired trait representing a breed- or subtype-specific feature. The genomic changes that emerged due to strong-targeted selection towards this distinct type remain unclear. Results Comparisons of whole-genome sequencing data from two Miniature Shetland ponies and one standard-sized Shetland Pony, performed to elucidate genetic determinants for miniature size, revealed four synergistic variants, limiting withers height to 34.25 in. (87 cm). Runs of homozygosity regions were detected spanning these four variants in both the Miniature Shetland ponies and the standard-sized Shetland Pony. They were shown to be characteristic of the Shetland Pony breed, resulting in a miniature type under specific genotypic combinations. These four genetic variants explained 72% of the size variation among Shetland ponies and related breeds. The length of the homozygous regions indicate that they arose over 1000 years ago. In addition, a copy number variant was identified in DIAPH3 harboring a loss exclusively in ponies and donkeys and thus representing a potential height-associated variant. Conclusion This study reveals main drivers for miniature size in horses identified in whole genome data and thus provides relevant candidate genes for extremely short stature in mammals.

  • Genome data uncover four synergistic key regulators for extremely small body size in horses.
    BMC Genomics, 2018
    Co-Authors: Julia Metzger, Janina Rau, Fanny Naccache, Laura Bas Conn, Gabriella Lindgren, Ottmar Distl
    Abstract:

    Miniature size in horses represents an extreme reduction of withers height that originated after domestication. In some breeds, it is a highly desired trait representing a breed- or subtype-specific feature. The genomic changes that emerged due to strong-targeted selection towards this distinct type remain unclear. Comparisons of whole-genome sequencing data from two Miniature Shetland ponies and one standard-sized Shetland Pony, performed to elucidate genetic determinants for miniature size, revealed four synergistic variants, limiting withers height to 34.25 in. (87 cm). Runs of homozygosity regions were detected spanning these four variants in both the Miniature Shetland ponies and the standard-sized Shetland Pony. They were shown to be characteristic of the Shetland Pony breed, resulting in a miniature type under specific genotypic combinations. These four genetic variants explained 72% of the size variation among Shetland ponies and related breeds. The length of the homozygous regions indicate that they arose over 1000 years ago. In addition, a copy number variant was identified in DIAPH3 harboring a loss exclusively in ponies and donkeys and thus representing a potential height-associated variant. This study reveals main drivers for miniature size in horses identified in whole genome data and thus provides relevant candidate genes for extremely short stature in mammals.

  • Additional file 8 of Genome data uncover four synergistic key regulators for extremely small body size in horses
    2018
    Co-Authors: Julia Metzger, Janina Rau, Fanny Naccache, Laura Bas Conn, Gabriella Lindgren, Ottmar Distl
    Abstract:

    Intersection of potential Shetland Pony-specific CNV regions (CNVRs). The overlap of four CNV detection results for Shetland Pony-specific CNVRs shows 97 CNVR harboring 14 different genes. (DOCX 18 kb

  • Additional file 7 of Genome data uncover four synergistic key regulators for extremely small body size in horses
    2018
    Co-Authors: Julia Metzger, Janina Rau, Fanny Naccache, Laura Bas Conn, Gabriella Lindgren, Ottmar Distl
    Abstract:

    Characterization of potential Shetland Pony-specific CNV regions. The size of the 97 CNV regions identified in the intersection of all four CNV detection runs for Shetland Pony-specific CNVs is shown in base pairs (bp) per chromosome. The number and size of all CNV regions varies among the chromosomes. On eleven chromosomes, no CNV region could be found in the overlapping results. (TIFF 16611 kb

  • Additional file 4 of Genome data uncover four synergistic key regulators for extremely small body size in horses
    2018
    Co-Authors: Julia Metzger, Janina Rau, Fanny Naccache, Laura Bas Conn, Gabriella Lindgren, Ottmar Distl
    Abstract:

    Results from variant effect prediction analysis. All genetic variants with predicted high or moderate effects in shared Shetland Pony ROH regions were evaluated for their effects, potential amino acid change and SIFT predictions. (XLSX 111 kb

Christine Aurich - One of the best experts on this subject based on the ideXlab platform.

  • seasonal changes in the sperm fatty acid composition of Shetland Pony stallions
    Theriogenology, 2018
    Co-Authors: Christine Aurich, Cristina Ortega Ferrusola, Fernando Juan Pena Vega, Nadine Schrammel, David Morcuende, Jorg Aurich
    Abstract:

    Spermatozoa contain polyunsaturated fatty acids (PUFA). Cryopreservation damages sperm membranes and they become less functional after thawing. We analysed the lipid composition of spermatozoa from Shetland stallions (n = 15) collected monthly from January to June and hypothesized that sperm lipid patterns change with season. In addition, one ejaculate per month was submitted to cryopreservation. Content of saturated palmytic and stearic acid decreased from January to March (p < 0.001) while content of the PUFA docosapentaenoic (p < 0.001) and arachidonic acid (p < 0.05) and total PUFA (p < 0.001) increased. Docosapentaenoic acid was the predominant PUFA in stallion spermatozoa. In conclusion, the sperm fatty acid composition of Shetland Pony stallions undergoes seasonal changes, and PUFA content increases from the non-breeding to the breeding season. Seasonal differences in sperm fatty acids might in part explain seasonal differences in the resistance of equine spermatozoa to cryopreservation and cooled-storage.

  • Seasonal changes in the sperm fatty acid composition of Shetland Pony stallions.
    Theriogenology, 2018
    Co-Authors: Christine Aurich, Cristina Ortega Ferrusola, Fernando Juan Pena Vega, Nadine Schrammel, David Morcuende, Jorg Aurich
    Abstract:

    Spermatozoa contain polyunsaturated fatty acids (PUFA). Cryopreservation damages sperm membranes and they become less functional after thawing. We analysed the lipid composition of spermatozoa from Shetland stallions (n = 15) collected monthly from January to June and hypothesized that sperm lipid patterns change with season. In addition, one ejaculate per month was submitted to cryopreservation. Content of saturated palmytic and stearic acid decreased from January to March (p 

  • effects of environmental temperature and season on hair coat characteristics physiologic and reproductive parameters in Shetland Pony stallions
    Theriogenology, 2017
    Co-Authors: Kathrin Schmidt, Jorg Aurich, Katharina Deichsel, Rodrigo Arruda De Oliveira, Natascha Ille, Christine Aurich
    Abstract:

    We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland Pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured once weekly. Heart rate, heart rate variability, testosterone and cortisol concentration in blood as well as quality and length of the coat were determined. Semen was collected once weekly and raw semen characteristics were analyzed. The characteristics of cooled-stored and cryopreserved semen were determined once monthly. During the stabling period, environmental temperature for group ST averaged 13.6 ± 2.3 and for group CON 5.6 ± 4.2 °C. The mean rectal temperature was higher (p < 0.05) in ST than in CON stallions. All hair coat parameters underwent seasonal changes (p < 0.001) and differed between groups (p < 0.05) with shorter guard hair, slower hair regrowth and earlier hair change in ST stallions. Season influenced heart rate which was highest in autumn, lowest in winter and intermediate in spring but did not differ between groups. Testosterone and cortisol concentrations in blood as well as sexual behavior underwent seasonal changes but did not differ between CON and ST stallions. Gel-free semen volume and total sperm count were influenced by season (p < 0.01) and showed a more pronounced increase from winter to spring in CON than in ST stallions (p < 0.05) while no differences with regard to sperm concentration in raw semen were detected. Progressive motility of spermatozoa in raw semen was highest in spring (p < 0.05) but not affected by group. In cooled-stored and cryopreserved semen, neither season nor group affected total motility, progressive motility or membrane integrity. In conclusion, environmental temperature during autumn and winter had clear results on body temperature as well as hair coat characteristics in Shetland stallions. Simultaneously determined effects on semen characteristics were minimal indicating that reproductive function in the horse is more dependent on day length i.e. the geophysical year than on other environmental factors.

  • Effects of environmental temperature and season on hair coat characteristics, physiologic and reproductive parameters in Shetland Pony stallions.
    Theriogenology, 2017
    Co-Authors: Kathrin Schmidt, Jorg Aurich, Katharina Deichsel, Rodrigo Arruda De Oliveira, Natascha Ille, Christine Aurich
    Abstract:

    We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland Pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured once weekly. Heart rate, heart rate variability, testosterone and cortisol concentration in blood as well as quality and length of the coat were determined. Semen was collected once weekly and raw semen characteristics were analyzed. The characteristics of cooled-stored and cryopreserved semen were determined once monthly. During the stabling period, environmental temperature for group ST averaged 13.6 ± 2.3 and for group CON 5.6 ± 4.2 °C. The mean rectal temperature was higher (p 

  • effects of a long day light programme on the motility and membrane integrity of cooled stored and cyropreserved semen in Shetland Pony stallions
    Animal Reproduction Science, 2016
    Co-Authors: Katharina Deichsel, Jorg Aurich, Nadine Schrammel, Christine Aurich
    Abstract:

    Abstract Increasing day length in spring stimulates reproductive functions in horses. In this study, we have analysed the effect of artificial long days on the quality of cooled-stored and cryopreserved semen in Shetland stallions. Stallions of the treatment group (AL, n = 8) were exposed to 16 h light and 8 h darkness from 15th December to 20th March while control stallions (CON, n = 7) were kept under natural photoperiod. Semen was collected once weekly and processed for cooled-storage and cryopreservation once per month. Total and progressive motility and percentage of membrane intact spermatozoa were analysed at 24, 48 and 72 h of cooled-storage and after freezing-thawing, respectively. Total and progressive motility and membrane integrity decreased during cooled-storage for 72 h in each month and both groups (p

Jorg Aurich - One of the best experts on this subject based on the ideXlab platform.

  • seasonal changes in the sperm fatty acid composition of Shetland Pony stallions
    Theriogenology, 2018
    Co-Authors: Christine Aurich, Cristina Ortega Ferrusola, Fernando Juan Pena Vega, Nadine Schrammel, David Morcuende, Jorg Aurich
    Abstract:

    Spermatozoa contain polyunsaturated fatty acids (PUFA). Cryopreservation damages sperm membranes and they become less functional after thawing. We analysed the lipid composition of spermatozoa from Shetland stallions (n = 15) collected monthly from January to June and hypothesized that sperm lipid patterns change with season. In addition, one ejaculate per month was submitted to cryopreservation. Content of saturated palmytic and stearic acid decreased from January to March (p < 0.001) while content of the PUFA docosapentaenoic (p < 0.001) and arachidonic acid (p < 0.05) and total PUFA (p < 0.001) increased. Docosapentaenoic acid was the predominant PUFA in stallion spermatozoa. In conclusion, the sperm fatty acid composition of Shetland Pony stallions undergoes seasonal changes, and PUFA content increases from the non-breeding to the breeding season. Seasonal differences in sperm fatty acids might in part explain seasonal differences in the resistance of equine spermatozoa to cryopreservation and cooled-storage.

  • Seasonal changes in the sperm fatty acid composition of Shetland Pony stallions.
    Theriogenology, 2018
    Co-Authors: Christine Aurich, Cristina Ortega Ferrusola, Fernando Juan Pena Vega, Nadine Schrammel, David Morcuende, Jorg Aurich
    Abstract:

    Spermatozoa contain polyunsaturated fatty acids (PUFA). Cryopreservation damages sperm membranes and they become less functional after thawing. We analysed the lipid composition of spermatozoa from Shetland stallions (n = 15) collected monthly from January to June and hypothesized that sperm lipid patterns change with season. In addition, one ejaculate per month was submitted to cryopreservation. Content of saturated palmytic and stearic acid decreased from January to March (p 

  • effects of environmental temperature and season on hair coat characteristics physiologic and reproductive parameters in Shetland Pony stallions
    Theriogenology, 2017
    Co-Authors: Kathrin Schmidt, Jorg Aurich, Katharina Deichsel, Rodrigo Arruda De Oliveira, Natascha Ille, Christine Aurich
    Abstract:

    We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland Pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured once weekly. Heart rate, heart rate variability, testosterone and cortisol concentration in blood as well as quality and length of the coat were determined. Semen was collected once weekly and raw semen characteristics were analyzed. The characteristics of cooled-stored and cryopreserved semen were determined once monthly. During the stabling period, environmental temperature for group ST averaged 13.6 ± 2.3 and for group CON 5.6 ± 4.2 °C. The mean rectal temperature was higher (p < 0.05) in ST than in CON stallions. All hair coat parameters underwent seasonal changes (p < 0.001) and differed between groups (p < 0.05) with shorter guard hair, slower hair regrowth and earlier hair change in ST stallions. Season influenced heart rate which was highest in autumn, lowest in winter and intermediate in spring but did not differ between groups. Testosterone and cortisol concentrations in blood as well as sexual behavior underwent seasonal changes but did not differ between CON and ST stallions. Gel-free semen volume and total sperm count were influenced by season (p < 0.01) and showed a more pronounced increase from winter to spring in CON than in ST stallions (p < 0.05) while no differences with regard to sperm concentration in raw semen were detected. Progressive motility of spermatozoa in raw semen was highest in spring (p < 0.05) but not affected by group. In cooled-stored and cryopreserved semen, neither season nor group affected total motility, progressive motility or membrane integrity. In conclusion, environmental temperature during autumn and winter had clear results on body temperature as well as hair coat characteristics in Shetland stallions. Simultaneously determined effects on semen characteristics were minimal indicating that reproductive function in the horse is more dependent on day length i.e. the geophysical year than on other environmental factors.

  • Effects of environmental temperature and season on hair coat characteristics, physiologic and reproductive parameters in Shetland Pony stallions.
    Theriogenology, 2017
    Co-Authors: Kathrin Schmidt, Jorg Aurich, Katharina Deichsel, Rodrigo Arruda De Oliveira, Natascha Ille, Christine Aurich
    Abstract:

    We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland Pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured once weekly. Heart rate, heart rate variability, testosterone and cortisol concentration in blood as well as quality and length of the coat were determined. Semen was collected once weekly and raw semen characteristics were analyzed. The characteristics of cooled-stored and cryopreserved semen were determined once monthly. During the stabling period, environmental temperature for group ST averaged 13.6 ± 2.3 and for group CON 5.6 ± 4.2 °C. The mean rectal temperature was higher (p 

  • effects of a long day light programme on the motility and membrane integrity of cooled stored and cyropreserved semen in Shetland Pony stallions
    Animal Reproduction Science, 2016
    Co-Authors: Katharina Deichsel, Jorg Aurich, Nadine Schrammel, Christine Aurich
    Abstract:

    Abstract Increasing day length in spring stimulates reproductive functions in horses. In this study, we have analysed the effect of artificial long days on the quality of cooled-stored and cryopreserved semen in Shetland stallions. Stallions of the treatment group (AL, n = 8) were exposed to 16 h light and 8 h darkness from 15th December to 20th March while control stallions (CON, n = 7) were kept under natural photoperiod. Semen was collected once weekly and processed for cooled-storage and cryopreservation once per month. Total and progressive motility and percentage of membrane intact spermatozoa were analysed at 24, 48 and 72 h of cooled-storage and after freezing-thawing, respectively. Total and progressive motility and membrane integrity decreased during cooled-storage for 72 h in each month and both groups (p

Alexander Riek - One of the best experts on this subject based on the ideXlab platform.

  • Saving energy during hard times: energetic adaptations of Shetland Pony mares.
    The Journal of experimental biology, 2014
    Co-Authors: Lea Brinkmann, Martina Gerken, Catherine Hambly, John R Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland Pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher field metabolic rate (FMR; 63.4±15.0 MJ day(-1)) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day(-1), respectively). During summer, locomotor activity, resting heart rate and total water turnover were considerably elevated (P

  • Saving energy during hard times: energetic adaptations of Shetland Pony mares
    Journal of Experimental Biology, 2014
    Co-Authors: Lea Brinkmann, Martina Gerken, Catherine Hambly, John R Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland Pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher field metabolic rate (FMR; 63.4±15.0 MJ day –1 ) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day –1 , respectively). During summer, locomotor activity, resting heart rate and total water turnover were considerably elevated ( P N =5) compensated for the decreased energy supply by reducing their FMR by 26% compared with control animals ( N =5). Furthermore, resting heart rate, body mass and body condition score were lower (29.2±2.7 beats min –1 , 140±22 kg and 3.0±1.0 points, respectively) than in control animals (36.8±41 beats min –1 , 165±31 kg, 4.4±0.7 points; P

  • Seasonal changes of total body water and water intake in Shetland ponies measured by an isotope dilution technique
    Journal of Animal Science, 2013
    Co-Authors: Lea Brinkmann, Martina Gerken, Alexander Riek
    Abstract:

    Water is an essential nutrient necessary to support life, and adequate water supply is crucial for animal survival and productivity. The present study was designed to determine seasonal changes in the water metabolism of horses under outdoor conditions. Total body water (TBW) and total water intake (TWI) of 10 adult Shetland Pony mares were estimated at monthly intervals for 14 mo by using the deuterium dilution technique. During the last 4 mo, 5 ponies were fed restrictively to simulate natural feed shortage in winter, and 5 ponies served as controls. The TBW (kg) was closely related to body mass [TBW (kg) = -2.86 + 0.67 × body mass (kg); P 0°C. Therefore, removing TWI values measured at Ta < 0°C from the analysis resulted in high correlations with locomotor activity (r = 0.87), Ta (r = 0.86), and resting heart rate (r = 0.88). The multiple regression among TWI, Ta, and heart rate explained 84% of the variation in TWI [TWI (mL·kg(-1)·d(-1)) = -13.38 + 1.77 × heart rate (beats/min) + 2.11 × Ta (°C); P < 0.001]. Feed restriction had no effect on TWI and TBW. The TBW content was unaffected by season and physical activity. The established regression equation for TBW and body mass can be used to predict TBW from body mass in ponies under field conditions. The comparison of TWI with published data on drinking water intake revealed that ponies had 1.7 to 5.1 times greater total water intakes when other sources of water such as feed and metabolic water were included. The TWI was highly influenced by environmental conditions and metabolic rate. Contrary to expectation, water supply during the cold seasons might be more critical than under summer conditions when water content of grass is high to allow for the compensation of limited availability of drinking water.

  • Effect of long-term feed restriction on the health status and welfare of a robust horse breed, the Shetland Pony (Equus ferus caballus).
    Research in Veterinary Science, 2013
    Co-Authors: Lea Brinkmann, Martina Gerken, Alexander Riek
    Abstract:

    Outdoor group housing is increasingly recognized as an appropriate housing system for domesticated horses. The objective of this study was therefore to investigate the effect of potential feed shortage in semi-natural horse keeping systems in winter on animal health and welfare. In 10 female Shetland ponies blood concentrations (NEFA, total protein (TP), total bilirubin (TB), beta-hydroxybutyrate (BHB) and thyroxine (T4)), body mass and the body condition score (BCS) were monitored for 7 months including a 4 months period of feed restriction in five of the 10 ponies. Restrictively fed animals lost 18.4 ± 2.99% of their body mass and the BCS decreased by 2.2 ± 0.8 points (BCS scale: 0 = emaciated, 5 = obese). Feed restriction led to a continuous increase in TB (P < 0.001) and NEFA (P < 0.01) concentrations compared to control ponies. The TP and BHB values only differed at the end of the trial with lower concentrations in restricted fed mares (P < 0.05). Feed restriction had no effect on thyroxine concentrations. TB concentrations in the feed restricted group were out of the reference range during the entire feeding trial. The increased NEFA concentrations in feed restricted compared to control ponies suggest that fat was mobilized. The BCS, as well as plasma NEFA and TB concentrations were good indicators for a rapid detection of possible health problems caused by undernourishment in horses when kept under semi-natural conditions. In contrast, blood parameters of the control animals were within the reference ranges, suggesting that a year round outdoor housing with additional feed supply is an adequate housing system for a robust horse breed like the Shetland Pony.

  • adaptation strategies to seasonal changes in environmental conditions of a domesticated horse breed the Shetland Pony equus ferus caballus
    The Journal of Experimental Biology, 2012
    Co-Authors: Lea Brinkmann, Martina Gerken, Alexander Riek
    Abstract:

    Recent results suggest that the wild ancestor of the horse, the Przewalski horse, exhibits signs of a hypometabolism. However, there are speculations that domestic animals lost the ability to reduce energy expenditure during food shortage and adverse environmental conditions. Therefore, we investigated physiological and behavioural strategies employed by a robust domesticated horse breed, the Shetland Pony, over the course of a year under temperate conditions by measuring ambient temperature ( T a), subcutaneous temperature ( T s), locomotor activity (LA), lying time, resting heart rate, body mass and body condition score. Ten animals were kept on pasture in summer and in open stables in winter; further, in winter the animals were allocated into one control and one feed-restricted group of five animals each to simulate natural seasonal food shortage. The annual course of the mean daily T s of all horses showed distinct fluctuations from a mean of 35.6±0.5°C, with higher variations in summer than in winter. Diurnal amplitudes in T s were highest ( P <0.001) in April (12.6°C) and lowest in January (4.0°C), with a nadir around dawn and a peak around mid-day. The feed-restricted group had a significantly lower daily T s compared with the control group on cold winter days, with T a values below 0°C. Mean annual heart rate and LA followed T a closely. Heart rate of the feed-restricted animals significantly decreased from a mean of 52.8±8.1 beats min–1 in summer to 29±3.9 beats min–1 in winter and differed from the control group ( P <0.001). Mean daily LA was lowest at the end of winter (7000 activity impulses day–1) and highest in summer (25,000 activity impulses day–1). Our results show that Shetland ponies exhibit signs of a winter hypometabolism indicated by reduced heart rate and T s. Thus, domesticated horses seem to have maintained the capacity for seasonal adaptation to environmental conditions by seasonal fluctuations in their metabolic rate.