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Comparison of feed intake behavior between cool- and warm-season hays offered at restricted and ad libitum rates
Abstracts / Journal of Equine Veterinary Science 52 (2017) 96e109
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Posters 148 Phosphorus release from Florida soils amended with different equine manures L.A. Skurupey*, M.W. Clark, G.J. Hochmuth, L.K. Warren University of Florida, Gainesville, FL, USA Unintentional movement of phosphorus (P) from horse manure to water sources is an environmental concern. This study assessed the effect of the horse’s diet on potential risk of P loss when the resulting manure was incorporated with soil. Soil P storage capacity (SPSC) calculated with and without magnesium (Mg) were also compared for their ability to predict P loss from manure-amended soils. Three soils amended with 5 fertilizers were evaluated in a 3 5 factorial arrangement. Soils originated from 3 pastures in Florida and represented a range in soil characteristics. Three organic fertilizers consisted of feces from horses consuming diets that provided similar P intake but Ca:P ratios of 1.1 (1HAY) or 2.7, where additional Ca was supplied by legume hay (3ALF) or inorganic supplementation (3SUP). The resulting feces differed in water-soluble P (WSP) content (3ALF <3SUP <1HAY; P < 0.05). The remaining 2 fertilizers were inorganic KH2PO4 and no fertilizer (soil only; CON). Soils were blended with fertilizers at the same P application rate (19.23 kg P/ha; recommended for bahiagrass pastures) and placed in 250mL cups. Each soil fertilizer treatment (n ¼ 15) was replicated 3 times and incubated for 7 d at outdoor temperatures (25 ± 0.3 C) at 100% field moisture capacity. Samples were obtained before and after incubation and analyzed for pH, WSP, and Mehlich-3 extracted minerals. Data were compared with a mixed model ANOVA. Relationships between SPSC and WSP were evaluated with bivariate regression. Before incubation, WSP release generally followed the WSP content of the fertilizers (CON <3ALF 3SUP 1HAY < KH2PO4; P < 0.05). Except for CON, WSP decreased after incubation in all treatments (P < 0.05). After incubation WSP from soils amended with KH2PO4 was similar to organic fertilizers; but, WSP from 3ALF-amended soils remained lower than 1HAY soils (P < 0.05). Although Melich-3 Ca differed between soils (P < 0.0001), soil had no effect on WSP release, indicating limited effect of soil Ca on manure P mobility. Mehlich-3 P was affected by soil (P < 0.0001), fertilizer (P < 0.0001; KH2PO4 < organic fertilizers) and soil fertilizer (P ¼ 0.02), but was not altered by incubation. SPSC was a poor predictor of P release in soils amended with feces before incubation (R2 ¼ 0.41), but showed improved predictive capacity after incubation (R2 ¼ 0.68) and was only slightly better with Mg in the equation (R2 ¼ 0.70). Assessment of WSP in equine feces appears to reflect potential for short-term P loss after land application. Thus, diet modifications to reduce WSP excretion are a reasonable management tool for reducing P loss. Key Words: water-soluble phosphorus, equine feces, manure fertilizer
149 Comparison of feed intake behavior between cool- and warm-season hays offered at restricted and ad libitum rates E.L. Chizek, T.L. Hansen, O.K. Zugay, L.K. Warren* University of Florida, Gainesville, FL, USA An association between ileal impaction and Coastal bermudagrass (Cynodon dactylon) hay has been reported in horses. Some have attributed this to the hay being dry and stemmy, whereas others
speculate horses may consume it faster with less chewing; however, investigation into potential causative factors has received little attention. In this study, 5 mature Quarter Horse geldings (mean ± SEM, 552 ± 14 kg) were used in a 5 5 Latin square design experiment to compare feed and water intake behavior in response to 5 hays: alfalfa (Medicago sativa), orchardgrass (Dactylis glomerata), and 3 Coastal bermudagrass hays harvested at 4, 6 or 8-wk of regrowth. Each 14-d period consisted of 10.5 d at a restricted feeding rate (1.62% BW/d, DM basis; fed as 2 meals/d) followed by 3.5 d at an ad libitum rate to evaluate response to an abrupt shift in feeding management. Rate of intake, chewing and swallowing activity, saliva production, bite frequency, and water intake were evaluated twice daily on d 6e10 (restricted) and d 11e14 (ad libitum). Time to consume a meal (restricted) and voluntary dry matter intake (ad libitum) were also recorded. Data were compared using general linear and mixed model ANOVA. Stem length (P < 0.0001) and diameter (P < 0.0001) were smaller, whereas tensile strength (P < 0.05) and NDF content (P < 0.05) were greater in Coastal bermudagrass hays compared with alfalfa and orchardgrass. When intake was restricted, horses consumed alfalfa hay faster (P < 0.05) with a greater rate of chewing (P < 0.05) than grass hays. Intake behaviors were not affected by hay type when fed ad libitum. Rates of intake (P < 0.0001), mastication (P < 0.0001), and bites of hay (P ¼ 0.02) were slower when offered hay ad libitum than when hay was restricted. When expressed relative to DM intake, intake time (P < 0.0001), chewing activity (P < 0.0001) and bite frequency (P ¼ 0.0001) were greater when offered hay ad libitum compared with restricted. Water intake was greater with alfalfa than 4- and 6-wk regrowth Coastal bermudagrass during restricted intake (P < 0.05), but was not different among hays during ad libitum feeding. Voluntary dry matter intake of alfalfa was greater than 8-wk regrowth Coastal bermudagrass (P < 0.05), but similar among other hays. Ingestive behaviors were influenced by forage type (alfalfa vs. grass) when daily intake was restricted, but not when horses were managed with ad libitum access to hay. Responses to warm-season grass hay differed little from coolseason grass hay despite physical and chemical differences, and did not appear to be altered by the maturity of Coastal bermudagrass. Key Words: horse, coastal bermudagrass, rate of intake
150 Hay-rake type affects ash content of alfalfa hay A.E. Neu*1, C.C. Sheaffer 2, D.J. Undersander 3, M.H. Hall 4, D.M. Kniffen 5, M.S. Wells 2, D.N. Catalano 1, K.L. Martinson 1 1 Department of Animal Science, University of Minnesota, St. Paul, MN USA; 2 Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN USA; 3 University of Wisconsin, Madison, WI, USA; 4 Department of Plant Science, Pennsylvania State University, University Park, PA, USA; 5 Department of Animal Science, Pennsylvania State University, University Park, PA, USA Ash includes minerals plants normally contain plus soil contamination. High ash content in hay is problematic since ash provides no nutritional benefit to livestock. Ash content can be affected by equipment used during hay harvest, and it is thought that hay rake-type can impact ash content of hay. The objective of this research was to assess the effect of 4 rake-types on ash content and nutritive values of alfalfa (Medicago sativa L.) hay. Replicated trials were conducted on 2 cuttings of alfalfa hay in Minnesota, Pennsylvania, and Wisconsin during 2015. Hand samples were collected in 4 phases of the hay harvest: standing forage, post-cut, post-rake and post-bale or chop. During raking, 2 swath rows in
105
Posters 148 Phosphorus release from Florida soils amended with different equine manures L.A. Skurupey*, M.W. Clark, G.J. Hochmuth, L.K. Warren University of Florida, Gainesville, FL, USA Unintentional movement of phosphorus (P) from horse manure to water sources is an environmental concern. This study assessed the effect of the horse’s diet on potential risk of P loss when the resulting manure was incorporated with soil. Soil P storage capacity (SPSC) calculated with and without magnesium (Mg) were also compared for their ability to predict P loss from manure-amended soils. Three soils amended with 5 fertilizers were evaluated in a 3 5 factorial arrangement. Soils originated from 3 pastures in Florida and represented a range in soil characteristics. Three organic fertilizers consisted of feces from horses consuming diets that provided similar P intake but Ca:P ratios of 1.1 (1HAY) or 2.7, where additional Ca was supplied by legume hay (3ALF) or inorganic supplementation (3SUP). The resulting feces differed in water-soluble P (WSP) content (3ALF <3SUP <1HAY; P < 0.05). The remaining 2 fertilizers were inorganic KH2PO4 and no fertilizer (soil only; CON). Soils were blended with fertilizers at the same P application rate (19.23 kg P/ha; recommended for bahiagrass pastures) and placed in 250mL cups. Each soil fertilizer treatment (n ¼ 15) was replicated 3 times and incubated for 7 d at outdoor temperatures (25 ± 0.3 C) at 100% field moisture capacity. Samples were obtained before and after incubation and analyzed for pH, WSP, and Mehlich-3 extracted minerals. Data were compared with a mixed model ANOVA. Relationships between SPSC and WSP were evaluated with bivariate regression. Before incubation, WSP release generally followed the WSP content of the fertilizers (CON <3ALF 3SUP 1HAY < KH2PO4; P < 0.05). Except for CON, WSP decreased after incubation in all treatments (P < 0.05). After incubation WSP from soils amended with KH2PO4 was similar to organic fertilizers; but, WSP from 3ALF-amended soils remained lower than 1HAY soils (P < 0.05). Although Melich-3 Ca differed between soils (P < 0.0001), soil had no effect on WSP release, indicating limited effect of soil Ca on manure P mobility. Mehlich-3 P was affected by soil (P < 0.0001), fertilizer (P < 0.0001; KH2PO4 < organic fertilizers) and soil fertilizer (P ¼ 0.02), but was not altered by incubation. SPSC was a poor predictor of P release in soils amended with feces before incubation (R2 ¼ 0.41), but showed improved predictive capacity after incubation (R2 ¼ 0.68) and was only slightly better with Mg in the equation (R2 ¼ 0.70). Assessment of WSP in equine feces appears to reflect potential for short-term P loss after land application. Thus, diet modifications to reduce WSP excretion are a reasonable management tool for reducing P loss. Key Words: water-soluble phosphorus, equine feces, manure fertilizer
149 Comparison of feed intake behavior between cool- and warm-season hays offered at restricted and ad libitum rates E.L. Chizek, T.L. Hansen, O.K. Zugay, L.K. Warren* University of Florida, Gainesville, FL, USA An association between ileal impaction and Coastal bermudagrass (Cynodon dactylon) hay has been reported in horses. Some have attributed this to the hay being dry and stemmy, whereas others
speculate horses may consume it faster with less chewing; however, investigation into potential causative factors has received little attention. In this study, 5 mature Quarter Horse geldings (mean ± SEM, 552 ± 14 kg) were used in a 5 5 Latin square design experiment to compare feed and water intake behavior in response to 5 hays: alfalfa (Medicago sativa), orchardgrass (Dactylis glomerata), and 3 Coastal bermudagrass hays harvested at 4, 6 or 8-wk of regrowth. Each 14-d period consisted of 10.5 d at a restricted feeding rate (1.62% BW/d, DM basis; fed as 2 meals/d) followed by 3.5 d at an ad libitum rate to evaluate response to an abrupt shift in feeding management. Rate of intake, chewing and swallowing activity, saliva production, bite frequency, and water intake were evaluated twice daily on d 6e10 (restricted) and d 11e14 (ad libitum). Time to consume a meal (restricted) and voluntary dry matter intake (ad libitum) were also recorded. Data were compared using general linear and mixed model ANOVA. Stem length (P < 0.0001) and diameter (P < 0.0001) were smaller, whereas tensile strength (P < 0.05) and NDF content (P < 0.05) were greater in Coastal bermudagrass hays compared with alfalfa and orchardgrass. When intake was restricted, horses consumed alfalfa hay faster (P < 0.05) with a greater rate of chewing (P < 0.05) than grass hays. Intake behaviors were not affected by hay type when fed ad libitum. Rates of intake (P < 0.0001), mastication (P < 0.0001), and bites of hay (P ¼ 0.02) were slower when offered hay ad libitum than when hay was restricted. When expressed relative to DM intake, intake time (P < 0.0001), chewing activity (P < 0.0001) and bite frequency (P ¼ 0.0001) were greater when offered hay ad libitum compared with restricted. Water intake was greater with alfalfa than 4- and 6-wk regrowth Coastal bermudagrass during restricted intake (P < 0.05), but was not different among hays during ad libitum feeding. Voluntary dry matter intake of alfalfa was greater than 8-wk regrowth Coastal bermudagrass (P < 0.05), but similar among other hays. Ingestive behaviors were influenced by forage type (alfalfa vs. grass) when daily intake was restricted, but not when horses were managed with ad libitum access to hay. Responses to warm-season grass hay differed little from coolseason grass hay despite physical and chemical differences, and did not appear to be altered by the maturity of Coastal bermudagrass. Key Words: horse, coastal bermudagrass, rate of intake
150 Hay-rake type affects ash content of alfalfa hay A.E. Neu*1, C.C. Sheaffer 2, D.J. Undersander 3, M.H. Hall 4, D.M. Kniffen 5, M.S. Wells 2, D.N. Catalano 1, K.L. Martinson 1 1 Department of Animal Science, University of Minnesota, St. Paul, MN USA; 2 Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN USA; 3 University of Wisconsin, Madison, WI, USA; 4 Department of Plant Science, Pennsylvania State University, University Park, PA, USA; 5 Department of Animal Science, Pennsylvania State University, University Park, PA, USA Ash includes minerals plants normally contain plus soil contamination. High ash content in hay is problematic since ash provides no nutritional benefit to livestock. Ash content can be affected by equipment used during hay harvest, and it is thought that hay rake-type can impact ash content of hay. The objective of this research was to assess the effect of 4 rake-types on ash content and nutritive values of alfalfa (Medicago sativa L.) hay. Replicated trials were conducted on 2 cuttings of alfalfa hay in Minnesota, Pennsylvania, and Wisconsin during 2015. Hand samples were collected in 4 phases of the hay harvest: standing forage, post-cut, post-rake and post-bale or chop. During raking, 2 swath rows in