Digestion of hay protein in different segments of the equine digestive tract.
Mature ponies fitted with permanent ileal cannulas were used in a 3 X 3 Latin square experiment to quantify prececal, postileal and total tract digestion of hay protein. Coastal Bermuda grass (CB), containing 11.7% crude protein, and two qualities of alfalfa, containing 15.0% (low-protein alfalfa; LA) and 18.1% (high-protein alfalfa; HA) crude protein, were fed in coarsely chopped form at 2% of body weight daily. Total tract apparent digestibility of the N in HA (73.8%) was higher than that in CB (57.0%; P less than .05) and was slightly higher than that in LA (66.1%; P less than .10). Nitrogen in LA was apparently more digestible than that in CB (P less than .05). Apparent prececal digestibilities of N in LA and CB were 1.3% and 9.6%, respectively, and were lower (P less than .05), or tended to be lower (P less than .10), than the 21.0% observed for HA. In relative terms, an average of 9.4% of the total N digestion occurred in the upper tract when CB and LA were fed, whereas 28.5% of total N digestion occurred in the foregut when HA was fed. There was a slightly higher concentration of total plasma free amino acids (P less than .10) at 1 h postfeeding when horses were fed alfalfa. Also, N retention was higher when ponies were fed HA (P less than .05) than when LA or CB were fed. Apparent postileal N digestibility was 52.5% for CB, 65.7% for LA and 66.9% for HA. Differences were not significant, and the large intestine appeared to compensate for the inefficiency of N digestion in the upper tract.(ABSTRACT TRUNCATED AT 250 WORDS)
Gibbs
P G
PG
Dept. of Anim. Sci., Texas Agricultural Experiment Station, College Station 77843.
Potter
G D
GD
Schelling
G T
GT
Kreider
J L
JL
Boyd
C L
CL
D000821:Animal Feed; D000818:Animals; D004044:Dietary Proteins / Q000502:physiology*; D004063:Digestion; D004068:Digestive System Physiological Phenomena; D006736:Horses / Q000502:physiology*; D008297:Male; D010940:Plant Proteins / Q000502:physiology*
D004044:Dietary Proteins; D010940:Plant Proteins