Feed protein partitioning impacts horse fecal nitrogen profiles: A retrospective pilot study
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Published on: April 25, 2016
R W Springer1, M R Plowman1, N M Cherry2
1Department of Animal Science, College of Agriculture & Natural Resources, Tarleton State University, Stephenville, TX, USA, 76402.
Background:
Feeding horses excess crude protein (CP) leads to increased nitrogen excretion in urine and feces. However, evidence is lacking in how CP partitioning in the diet impacts nitrogen profiles in equine feces for potential fertilizer use.
Objectives:
Thus, our retrospective pilot study objective was to determine if daily CP and neutral detergent soluble CP (NDSCP) intakes affected equine fecal nitrogen profiles.
Methods:
Three Quarter Horse geldings were fed 15 g dry matter (DM)/kg body weight (BW)/d of coastal Bermudagrass hay for 14 d (GRASS) then 15 g DM/kg BW/d of a 50:50 mixture of coastal Bermudagrass and alfalfa hay for 14 d (MIXED). A concentrate with 158 g CP/kg DM was fed daily (0.5 kg DM/d). Fresh feces were collected on Day 14 of each phase and frozen at -80°C, then analyzed by Dairy One (Ithaca, NY, USA). Intake data (g/kg BW/d) and fecal analyses (g/kg DM) were analyzed using a paired t-test and ANCOVA using CP intake as a covariate.
Results:
The MIXED diet provided more NDSCP (2.04 g NDSCP/kg BW/d) than GRASS (1.50 g NDSCP/kg BW/d; P<0.001). Fecal ammonia concentration tended greater and fecal carbon concentration was less in MIXED versus GRASS (P=0.082; P=0.015). From the ANCOVA, MIXED had greater fecal ammonia (P=0.047) but less fecal-N (P=0.018) and organic-N (P=0.007) than GRASS.
Conclusion:
Increases in dietary NDSCP from greater CP intake increase excretion of nitrogen as fecal ammonia in a single hand-grab sample, which indicates that dietary protein fractionation may impact equine fecal nitrogen profiles and therefore, manure management.
