Protein quality and utilization of timothy, oat-supplemented timothy, and alfalfa at differing harvest maturities in exercised Arabian horses
| Autor: | Brian D. Nielsen, J.S. Liesman, T.E. Lavin, Nathalie L. Trottier, A.D. Woodward |
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| Rok vydání: | 2011 |
| Předmět: |
Male
Time Factors Urine Biology Arginine Poaceae Excretion Animal science Latin square Physical Conditioning Animal Genetics Animals Horses Feces Timothy-grass Cross-Over Studies food and beverages Horse General Medicine biology.organism_classification Animal Feed Diet Hay Animal Nutritional Physiological Phenomena Animal Science and Zoology Dietary Proteins Protein quality Medicago sativa Food Science |
| Zdroj: | Journal of Animal Science. 89:4081-4092 |
| ISSN: | 1525-3163 0021-8812 |
| DOI: | 10.2527/jas.2010-3825 |
| Popis: | To evaluate the protein quality and postgut N utilization of full-bloom timothy hay, oat-supplemented timothy-hay diets, and alfalfa hay harvested at different maturities, apparent whole tract N digestibility, urinary N excretion, and serum AA profiles were determined in light to moderately exercised Arabian horses. Six Arabian geldings (16.0 ± 0.3 yr; 467 ± 11 kg of BW) were randomly allocated to a 6 × 6 Latin square design. Diets included full-bloom timothy grass hay (G), G + 0.2% BW oat (G1), G + 0.4% BW oat (G2), mid-bloom alfalfa (A1), early-bloom alfalfa (A2), and early-bud alfalfa hay (A3). Forages were fed at 1.6% of the BW of the horse (as-fed). Each period consisted of an 11-d adaptation period followed by total collection of feces and urine for 3 d. Blood samples were taken on d 11 for analysis of serum AA concentrations. During the 3-d collection period, urine and feces were collected every 8 h and measured and weighed, respectively. Approximately 10% of the total urine volume and fecal weight per period was retained for N analyses. Fecal DM output was less (P0.05) in A1, A2, or A3 compared with G, G1, or G2. Apparent whole tract N digestibility was greater (P0.01) in A1, A2, and A3 compared with G, G1, or G2, and was greater (P0.05) in G1 and G2 compared with G. Nitrogen retention was not different from zero, and there were no differences (P0.05) in N retention among diets. Urinary N excretion and total N excretion were greater (P0.05) in A1, A2, and A3 compared with G, G1, or G2. Plasma concentrations for the majority of AA increased curvilinearly in response to feeding G, A1, A2, and A3 (quadratic, P0.05), with values appearing to maximize 2-h postfeeding. Although alfalfa N digestibility increased with decreasing harvest maturity, N retention did not differ and urinary volume and N excretion increased, indicating that postabsorptive N utilization decreased. In contrast, inclusion of oats at either 0.2 or 0.4% of the BW of the horse to timothy hay markedly enhanced N digestibility without increasing N excretion, indicating improvement in postgut N utilization. These findings indicate that feeding oat-supplemented timothy hay is more environmentally sustainable than feeding alfalfa to the horse at maintenance or under light to moderate exercise. |
| Databáze: | OpenAIRE |
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