Site and extent of amino acid digestion in dairy cattle fed with corn and its byproducts
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2015-02
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The study was conducted to evaluated the site and extent of dry matter (DM), crude protein (CP), methionine (Met), lysine (Lys), and threonine (Thr) digestion of corn and byproducts obtained from
corn germ mixed with different amounts of extruded or non-extruded ether extract (EE) in dairy cattle.
Treatments consisted in eight types of feed and two processing in a 4 × 2 factorial design. There were
four feeds: corn grain cracked (Corn), corn germ meal with 1% EE (CG1), corn germ meal with 7%
EE (CG7), and corn germ meal with 10% EE (CG10). The feeds were processed in one of two ways:
extruded (Ex) and not extruded. In situ techniques were used to determine DM, CP, Met, Lys, and Thr
partial and total tract digestion. A basic diet was compounded of corn germ meal, soybean meal and
coastcross hay in a 70:30 roughage to concentrate ratio. There was no interaction (P>0.05) between
feeds and processing method. Extrusion improved (P<0.05) total tract digestibility of corn DM but not
CP. Intestinal digestibility was similar (P>0.05) for corn and corn germ meal mixed with 7 and 10% EE,
regardless of EE processing method. The CP total tract digestibility of corn germ meal with 1% nonextruded
EE was 16.62% higher (P<0.05) than that of the extruded form. The best total CP digestibility
was obtained for corn germ meal with 7% EE, independently of the processing method. The effects of
EE processing method on partial and total digestibility differed between amino acid. Corn and corn
byproduct extrusion may improve dry matter digestibility, but do not necessarily influence crude protein
digestion. Ruminal and intestinal digestibility of Met, Lys, and Thr depends on both feed type and
processing method. Therefore, amino acid availability should be considered individually.
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Extrusion, Extrusão, Germ meal, Lysine, Methionine, Rumen, Farelo de gérmen, Lisina, Metionina, Rúmen
Citação
FERREIRA, Reginaldo Nassar et al. Site and extent of amino acid digestion in dairy cattle fed with corn and its byproducts. Semina: ciências agrárias, Londrina, v. 36, n. 1, p. 421-430, Jan./Feb. 2015.