- Email: [email protected]
Feed composition and animal factors affecting forage digestibility by horses
340
Abstracts / Journal of Equine Veterinary Science 33 (2013) 321-399
The LFHC diet consisted of grass hay (1.0% BW/d) and high NSC (42%) concentrate (1.2% BW/d). The NSC was starch plus WSC. Forage and concentrate meals were fed twice daily. Fecal pH measurements were recorded weekly. Every 14 d, SATs were performed to assess individual permeability. Sugars were administered via nasogastric tube at time 0 and total urine was collected over a 24 h period. Sugar excretion was quantified via gas chromatography with flame ionization detection. Data were analyzed using a mixed ANOVA with repeated measures. Percent excretion was greater in the LFHC horses for sucrose, mannitol, and sucralose, with no detected difference in lactulose excretion (P < 0.05). Fecal pH values were higher for the HFLC diets than the LFHC diets at 6.95 and 6.53 (P < 0.0001), respectively. The SATs may be an effective tool in measuring gastrointestinal permeability in the horse and provides evidence that high concentrate low forage diets increase gastrointestinal permeability and decrease hindgut pH.
Estimated digestible energy intakes in moderate and overweight horses J.C. Gill 1, S.E. Pratt-Phillips 1, R.A. Mansmann 2, and P. Siciliano 1 1 Department of Animal Science, North Carolina State University, Raleigh, NC 27695, 2 Equine Podiatry and Rehabilitation Practice, Chapel Hill, NC, 27517 Obesity in horses is an increasingly common problem, with significant health risks to the animal. Factors contributing to obesity include owner overfeeding, lush unrestricted pasture intake, and variation in basal metabolic rate between horses. As part of a larger weight-loss study, this preliminary study examined the differences in estimated digestible energy (DE) intakes in overweight horses compared to horses with moderate body condition scores (BCS). Twenty-four client-owned overweight horses, (BCS 7; mean SD 529 69 kg BW, 3 – 18 yr of age, mixed light breeds) were identified. Ten horses having moderate BCS (BCS < 6; 528 44kg BW, 6 – 23 yr of age, mixed light breeds) that were housed at facilities with the overweight horses were also identified. Horse evaluations included; girth circumference, body length, estimated body weight, height, girth to height ratio (G:H), BCS and cresty neck score (CNS). A dietary evaluation was conducted to obtain; feed types and weights, chemical composition analysis of hay and pasture, health history and exercise level. For NRC DE requirement estimation, overweight horses were categorized as “minimum maintenance”, “average maintenance” or “light work”, while moderate horses were categorized as “average maintenance”, “elevated maintenance” or “light work”. DE contents of feeds were calculated using chemical composition obtained through analysis or were obtained from feed companies. Free choice pasture intakes were estimated based on 2% BW DMI, and for horses that had restricted grazing, limited pasture quality, or other feeds, estimated intakes were adjusted. Mean BCS in the
overweight and moderate groups was 7.7 0.6 and 5.3 0.6, respectively (P<0.0001). Of the 24 horses in the overweight group, 9 were obese (BCS 8), with regional adiposity, dimpling of fat along the body and CNS 3. Mean G:H in the overweight group was 1.27 0.04, and 1.20 0.03 in the moderate group (P<0.0001). Overweight horses consumed an average 141.9 28.5% of their estimated DE requirements. However, this was not different from the moderate horses, who consumed an average of 145.4 28.8% of their estimated DE requirements. DE intakes when expressed as kcal/kg BW were not different, with mean DE intakes of 45.3 8.1 kcal/kg BW for overweight horses and 50.3 9.8 kcal/kg BW for moderate horses. DMI as % BW was not different between the two groups (2.0 0.3 for the overweight horses and 2.2 0.4 for the moderate horses). However, overweight horses had a greater proportion of their intake from pasture (P<0.01), and using 2% BW DMI may have underestimated intakes in these horses. Meanwhile, moderate horses had a greater proportion of their diet coming from hay (P<0.01) and concentrates (P<0.01), where intakes were more easily quantified. Discrepancies between estimated energy intakes and NRC requirements need further evaluation.
Feed composition and animal factors affecting forage digestibility by horses T.L. Hansen, and L.M. Lawrence Department of Animal and Food Sciences, University of Kentucky, Lexington, KY, 40546 The concentrations of neutral detergent fiber (NDF) and acid detergent fiber (ADF) are often used to assess forage quality in animal diets. Relative feed value (RFV) uses NDF and ADF to predict digestible dry matter in cattle; however, a comprehensive evaluation of the effect these forage characteristics have on dry matter digestibility (DMD) in horses has not been performed. A literature review on Google ScholarÒ was conducted between January 1, 2013 to January 23, 2013 for the terms digestibility, horses, and forages to locate in vivo digestibility studies in horses and ponies that were fed greater than 50% forage diets and included: NDF, ADF, and crude protein (CP) concentrations of feeds; DMD, NDF digestibility (NDFD), ADF digestibility (ADFD), and CP digestibility (CPD), DM intake (% BW), and animal factors such as age, gender, and breed. Additionally, the proceedings from the previous Equine Nutrition and Physiology/Equine Science Symposiums were searched for the same criteria. The search resulted in 15 articles and abstracts that included all of the necessary information and 24 additional studies containing partial information. Data from these studies were compiled and used for linear regression on DMD, NDFD, ADFD, and CPD by feed and animal characteristics. DMD was significantly related to the NDF, ADF, CP, difference between NDF and ADF (NDF-ADF), and percent ADF in NDF (P< 0.0001); however, multiple regression of DMD by NDF and CP content of the forage
Abstracts / Journal of Equine Veterinary Science 33 (2013) 321-399
showed the best fit to the data available (DMD ¼ 70.54715 – 0.38490 NDF + 0.40783 CP; P< 0.001; adjusted R2 ¼ 0.5552). Regression using data from growing horses indicated DMD could not be predicted by diet characteristics; however, this result may be influenced by the small data set (n ¼ 13). Stepwise regression of 15 studies with complete data was used to establish useful predictors for DMD, NDFD, ADFD, and CPD. Significant terms in the regression analysis for DMD included horse weight, breed, NDF, CP, and the study (P< 0.0001, adjusted R2 ¼ 0.8570). Significant terms for NDFD included horse weight, breed, type of forage (cool season legume, cool season grass, mixed forages, forage fed with grain, and warm season grasses), forage processing (pelleted, long stem, or mixed), NDF, NDF-ADF, ADF as a percentage of NDF, CP, and the study (P ¼ 0.012, adjusted R2 ¼ 0.5594). Significant terms for ADFD included type of forage, DM intake, horse weight, breed, NDF, NDF-ADF, CP, and the study (P< 0.0001, adjusted R2 ¼ 0.7607). Significant terms for CPD included type of forage, DM intake, ADF as a percentage of NDF, CP, and the study (P< 0.0001, adjusted R2 ¼ 0.7395). However, multicollinearity is expected in these models, and studies may need to be weighted to account for study variability due to methods. Predictive models of DMD, NDFD, ADFD, and CPD need to be developed further before practical application.
341
fecal particle length in the day 7 samples (Table 1; P¼0.93) or over the whole week (P¼0.3). Diet had no effect on intake time (LH¼110 min, CH¼115 min, SEM¼22; P¼0.86), PCV (LH¼42.1%, CH¼42.0%, SEM¼1.3; P¼0.88), or TS (LH¼7.0, CH¼7.0, SEM¼0.7; P¼0.74), although both PCV and TS increased over the 3-hr sampling period (P<0.01). Water consumption (LH¼22.6 kg/d, CH¼22.4 kg/d, SEM¼1.2) and fecal dry matter (22.8% for both groups, SEM¼0.2) did not differ between treatments (P¼0.9). Chopping hay did not have an impact on measured variables so its potential role in helping to maintain lower body temperature during endurance exercise remains unclear. Interestingly, only w10% of the fecal particles did not pass through the sieve of 2.36 mm and over 40% passed through a sieve of 150 mm, suggesting a marked reduction in particle size during the digestive process regardless of original intake length.
Table 1 Mean percent (and SEM) of fecal particles collected on day 7 according to size as measured using a wet sieve procedure Size
Chopped hay
Long hay
SEM
> 2.36 mm > 1.18 mm < 2.36 mm > 600 mm < 1.18 mm > 300 mm< 600 mm > 150 mm< 300 mm Less than 150 mm
10.0% 15.7% 14.7% 10.8% 6.8% 42.2%
9.5% 14.5% 14.5% 10.3% 6.5% 44.9%
0.5% 0.5% 0.5% 0.5% 0.5% 1.0%
Chopping hay before feeding does not influence fecal particle size, blood variables, or water intake in threeyear-old Arabians. R.A. LeCompte 1, B.D. Nielsen 1, C.I. Robison 1, and P. Harris 2 1 Department of Animal Science, Michigan State University, East Lansing, MI, USA 48824-1225, 2 WALTHAM Centre for Pet Nutrition, Leics, UK Previous work suggested that the form in which roughage is presented to horses (chopped versus long stem) may play a role in thermoregulation during prolonged exercise, potentially by influencing the dynamics of water release during digestion of hay particles. Hindgut particle size, therefore, may be an important factor, but the effect of chopping on this has not been evaluated.This study aimed to determine if chopping hay affects fecal particle size and whether this influences packed cell volume (PCV), plasma total solids (TS), or fecal water and particle length.Six 3-yrold Arabians in light training were divided into two groups of three horses for a 4-wk study. All horses were in good general and dental health. Each group was fed either long-stem alfalfa hay (LH) or the same hay chopped (CH; range 1 to 6 cm particle length) during wk 1. During wk 2, treatments were reversed, allowing acclimation. During wk 3 and 4, horses were given the same diets as wk 1 and 2, respectively. On day 7 (end wk 3 and 4 respectively), water consumption was measured over a 48-hr period, feed intake time was recorded, and PCV plus TS were measured at 0, 30, 60, 90, 120, 150, and 180 min post-hay feeding. Fecal samples were collected immediately after voiding each morning during wk 3 and 4 to determine fecal water and particle size. There was no effect of diet on
Metabolic effects of psyllium supplementation in horses grazing rapidly growing cool-season grass J.L. Rohrs, S.M. Moreaux, R.A. Frost, J. Weeding, and J.G. Berardinelli Department of Animal and Range Sciences, Montana State University, Bozeman, MT, 59717 Digestion of non-structural carbohydrates (NSC) from cool season pasture grasses can result in increased adiposity, risk of insulin resistance, and laminitis in horses [1]. Research has shown that lowering blood glucose levels and increasing insulin sensitivity will reduce the risk of laminitis and associated diseases [2]. Supplementing horses with psyllium reduces blood glucose and insulin concentrations in horses that are meal fed [3]. The objective of this study was to evaluate the effects of psyllium supplementation in horses grazing rapidly growing cool season grass. Eleven lightbreed stock horses (7 mares, 4 geldings, Age 13.5 2.5; mean SD) were individually confined in dry lots overnight and strip grazed for 8 hours daily for 30 days. Psyllium-supplemented horses received (n ¼ 6) 180 g of psyllium daily. All horses received an isocaloric protein supplement. Forage intake for each horse was calculated using a previously published equation [4]. Forage was analyzed for nutrient content every other week. Changes in metabolic characteristics were assessed by assay of glucose, insulin, leptin and adiponectin concentrations in blood samples collected on days 0, 8, 15, 22, and 29 at
Abstracts / Journal of Equine Veterinary Science 33 (2013) 321-399
The LFHC diet consisted of grass hay (1.0% BW/d) and high NSC (42%) concentrate (1.2% BW/d). The NSC was starch plus WSC. Forage and concentrate meals were fed twice daily. Fecal pH measurements were recorded weekly. Every 14 d, SATs were performed to assess individual permeability. Sugars were administered via nasogastric tube at time 0 and total urine was collected over a 24 h period. Sugar excretion was quantified via gas chromatography with flame ionization detection. Data were analyzed using a mixed ANOVA with repeated measures. Percent excretion was greater in the LFHC horses for sucrose, mannitol, and sucralose, with no detected difference in lactulose excretion (P < 0.05). Fecal pH values were higher for the HFLC diets than the LFHC diets at 6.95 and 6.53 (P < 0.0001), respectively. The SATs may be an effective tool in measuring gastrointestinal permeability in the horse and provides evidence that high concentrate low forage diets increase gastrointestinal permeability and decrease hindgut pH.
Estimated digestible energy intakes in moderate and overweight horses J.C. Gill 1, S.E. Pratt-Phillips 1, R.A. Mansmann 2, and P. Siciliano 1 1 Department of Animal Science, North Carolina State University, Raleigh, NC 27695, 2 Equine Podiatry and Rehabilitation Practice, Chapel Hill, NC, 27517 Obesity in horses is an increasingly common problem, with significant health risks to the animal. Factors contributing to obesity include owner overfeeding, lush unrestricted pasture intake, and variation in basal metabolic rate between horses. As part of a larger weight-loss study, this preliminary study examined the differences in estimated digestible energy (DE) intakes in overweight horses compared to horses with moderate body condition scores (BCS). Twenty-four client-owned overweight horses, (BCS 7; mean SD 529 69 kg BW, 3 – 18 yr of age, mixed light breeds) were identified. Ten horses having moderate BCS (BCS < 6; 528 44kg BW, 6 – 23 yr of age, mixed light breeds) that were housed at facilities with the overweight horses were also identified. Horse evaluations included; girth circumference, body length, estimated body weight, height, girth to height ratio (G:H), BCS and cresty neck score (CNS). A dietary evaluation was conducted to obtain; feed types and weights, chemical composition analysis of hay and pasture, health history and exercise level. For NRC DE requirement estimation, overweight horses were categorized as “minimum maintenance”, “average maintenance” or “light work”, while moderate horses were categorized as “average maintenance”, “elevated maintenance” or “light work”. DE contents of feeds were calculated using chemical composition obtained through analysis or were obtained from feed companies. Free choice pasture intakes were estimated based on 2% BW DMI, and for horses that had restricted grazing, limited pasture quality, or other feeds, estimated intakes were adjusted. Mean BCS in the
overweight and moderate groups was 7.7 0.6 and 5.3 0.6, respectively (P<0.0001). Of the 24 horses in the overweight group, 9 were obese (BCS 8), with regional adiposity, dimpling of fat along the body and CNS 3. Mean G:H in the overweight group was 1.27 0.04, and 1.20 0.03 in the moderate group (P<0.0001). Overweight horses consumed an average 141.9 28.5% of their estimated DE requirements. However, this was not different from the moderate horses, who consumed an average of 145.4 28.8% of their estimated DE requirements. DE intakes when expressed as kcal/kg BW were not different, with mean DE intakes of 45.3 8.1 kcal/kg BW for overweight horses and 50.3 9.8 kcal/kg BW for moderate horses. DMI as % BW was not different between the two groups (2.0 0.3 for the overweight horses and 2.2 0.4 for the moderate horses). However, overweight horses had a greater proportion of their intake from pasture (P<0.01), and using 2% BW DMI may have underestimated intakes in these horses. Meanwhile, moderate horses had a greater proportion of their diet coming from hay (P<0.01) and concentrates (P<0.01), where intakes were more easily quantified. Discrepancies between estimated energy intakes and NRC requirements need further evaluation.
Feed composition and animal factors affecting forage digestibility by horses T.L. Hansen, and L.M. Lawrence Department of Animal and Food Sciences, University of Kentucky, Lexington, KY, 40546 The concentrations of neutral detergent fiber (NDF) and acid detergent fiber (ADF) are often used to assess forage quality in animal diets. Relative feed value (RFV) uses NDF and ADF to predict digestible dry matter in cattle; however, a comprehensive evaluation of the effect these forage characteristics have on dry matter digestibility (DMD) in horses has not been performed. A literature review on Google ScholarÒ was conducted between January 1, 2013 to January 23, 2013 for the terms digestibility, horses, and forages to locate in vivo digestibility studies in horses and ponies that were fed greater than 50% forage diets and included: NDF, ADF, and crude protein (CP) concentrations of feeds; DMD, NDF digestibility (NDFD), ADF digestibility (ADFD), and CP digestibility (CPD), DM intake (% BW), and animal factors such as age, gender, and breed. Additionally, the proceedings from the previous Equine Nutrition and Physiology/Equine Science Symposiums were searched for the same criteria. The search resulted in 15 articles and abstracts that included all of the necessary information and 24 additional studies containing partial information. Data from these studies were compiled and used for linear regression on DMD, NDFD, ADFD, and CPD by feed and animal characteristics. DMD was significantly related to the NDF, ADF, CP, difference between NDF and ADF (NDF-ADF), and percent ADF in NDF (P< 0.0001); however, multiple regression of DMD by NDF and CP content of the forage
Abstracts / Journal of Equine Veterinary Science 33 (2013) 321-399
showed the best fit to the data available (DMD ¼ 70.54715 – 0.38490 NDF + 0.40783 CP; P< 0.001; adjusted R2 ¼ 0.5552). Regression using data from growing horses indicated DMD could not be predicted by diet characteristics; however, this result may be influenced by the small data set (n ¼ 13). Stepwise regression of 15 studies with complete data was used to establish useful predictors for DMD, NDFD, ADFD, and CPD. Significant terms in the regression analysis for DMD included horse weight, breed, NDF, CP, and the study (P< 0.0001, adjusted R2 ¼ 0.8570). Significant terms for NDFD included horse weight, breed, type of forage (cool season legume, cool season grass, mixed forages, forage fed with grain, and warm season grasses), forage processing (pelleted, long stem, or mixed), NDF, NDF-ADF, ADF as a percentage of NDF, CP, and the study (P ¼ 0.012, adjusted R2 ¼ 0.5594). Significant terms for ADFD included type of forage, DM intake, horse weight, breed, NDF, NDF-ADF, CP, and the study (P< 0.0001, adjusted R2 ¼ 0.7607). Significant terms for CPD included type of forage, DM intake, ADF as a percentage of NDF, CP, and the study (P< 0.0001, adjusted R2 ¼ 0.7395). However, multicollinearity is expected in these models, and studies may need to be weighted to account for study variability due to methods. Predictive models of DMD, NDFD, ADFD, and CPD need to be developed further before practical application.
341
fecal particle length in the day 7 samples (Table 1; P¼0.93) or over the whole week (P¼0.3). Diet had no effect on intake time (LH¼110 min, CH¼115 min, SEM¼22; P¼0.86), PCV (LH¼42.1%, CH¼42.0%, SEM¼1.3; P¼0.88), or TS (LH¼7.0, CH¼7.0, SEM¼0.7; P¼0.74), although both PCV and TS increased over the 3-hr sampling period (P<0.01). Water consumption (LH¼22.6 kg/d, CH¼22.4 kg/d, SEM¼1.2) and fecal dry matter (22.8% for both groups, SEM¼0.2) did not differ between treatments (P¼0.9). Chopping hay did not have an impact on measured variables so its potential role in helping to maintain lower body temperature during endurance exercise remains unclear. Interestingly, only w10% of the fecal particles did not pass through the sieve of 2.36 mm and over 40% passed through a sieve of 150 mm, suggesting a marked reduction in particle size during the digestive process regardless of original intake length.
Table 1 Mean percent (and SEM) of fecal particles collected on day 7 according to size as measured using a wet sieve procedure Size
Chopped hay
Long hay
SEM
> 2.36 mm > 1.18 mm < 2.36 mm > 600 mm < 1.18 mm > 300 mm< 600 mm > 150 mm< 300 mm Less than 150 mm
10.0% 15.7% 14.7% 10.8% 6.8% 42.2%
9.5% 14.5% 14.5% 10.3% 6.5% 44.9%
0.5% 0.5% 0.5% 0.5% 0.5% 1.0%
Chopping hay before feeding does not influence fecal particle size, blood variables, or water intake in threeyear-old Arabians. R.A. LeCompte 1, B.D. Nielsen 1, C.I. Robison 1, and P. Harris 2 1 Department of Animal Science, Michigan State University, East Lansing, MI, USA 48824-1225, 2 WALTHAM Centre for Pet Nutrition, Leics, UK Previous work suggested that the form in which roughage is presented to horses (chopped versus long stem) may play a role in thermoregulation during prolonged exercise, potentially by influencing the dynamics of water release during digestion of hay particles. Hindgut particle size, therefore, may be an important factor, but the effect of chopping on this has not been evaluated.This study aimed to determine if chopping hay affects fecal particle size and whether this influences packed cell volume (PCV), plasma total solids (TS), or fecal water and particle length.Six 3-yrold Arabians in light training were divided into two groups of three horses for a 4-wk study. All horses were in good general and dental health. Each group was fed either long-stem alfalfa hay (LH) or the same hay chopped (CH; range 1 to 6 cm particle length) during wk 1. During wk 2, treatments were reversed, allowing acclimation. During wk 3 and 4, horses were given the same diets as wk 1 and 2, respectively. On day 7 (end wk 3 and 4 respectively), water consumption was measured over a 48-hr period, feed intake time was recorded, and PCV plus TS were measured at 0, 30, 60, 90, 120, 150, and 180 min post-hay feeding. Fecal samples were collected immediately after voiding each morning during wk 3 and 4 to determine fecal water and particle size. There was no effect of diet on
Metabolic effects of psyllium supplementation in horses grazing rapidly growing cool-season grass J.L. Rohrs, S.M. Moreaux, R.A. Frost, J. Weeding, and J.G. Berardinelli Department of Animal and Range Sciences, Montana State University, Bozeman, MT, 59717 Digestion of non-structural carbohydrates (NSC) from cool season pasture grasses can result in increased adiposity, risk of insulin resistance, and laminitis in horses [1]. Research has shown that lowering blood glucose levels and increasing insulin sensitivity will reduce the risk of laminitis and associated diseases [2]. Supplementing horses with psyllium reduces blood glucose and insulin concentrations in horses that are meal fed [3]. The objective of this study was to evaluate the effects of psyllium supplementation in horses grazing rapidly growing cool season grass. Eleven lightbreed stock horses (7 mares, 4 geldings, Age 13.5 2.5; mean SD) were individually confined in dry lots overnight and strip grazed for 8 hours daily for 30 days. Psyllium-supplemented horses received (n ¼ 6) 180 g of psyllium daily. All horses received an isocaloric protein supplement. Forage intake for each horse was calculated using a previously published equation [4]. Forage was analyzed for nutrient content every other week. Changes in metabolic characteristics were assessed by assay of glucose, insulin, leptin and adiponectin concentrations in blood samples collected on days 0, 8, 15, 22, and 29 at