title: The influence of associative effects on the in vitro-estimated utilizable crude protein (uCP) of feeds for ruminants.
abstract: Nineteen feed mixtures, formulated with 16 single feeds, were used to study the influence of associative effects on utilizable crude protein (uCP) of feed mixtures. The in vitro incubation technique of Zhao and Lebzien (2000) was used for uCP determination. It was found that the in vitro-determined uCP (D-uCP) was significantly higher than the weighted uCP (W-uCP) of feed mixtures and there was a significant regressive relationship between W-uCP (x) [g x kg(-1)DM] and D-uCP (y) [g x kg(-1)DM]: y=(0.94 +/- 0.23)x + (18.78 +/- 35.58), r2=0.49, n=19, p < 0.01. It was concluded that there exist significant associative effects of feed mixtures on uCP. In formulation of rations for ruminants the D-uCP should be used instead of W-uCP. Because of the low regression coefficient of the equation above, the D-uCP cannot be estimated from the W-uCP.
authors.affiliation: College of Animal Science and Technology, China Agricultural University, Beijing, PR China. zhaogy@cau.edu.cn
authors.forename: Guang-Yong
authors.initials: GY
authors.lastname: Zhao
authors.forename: Yuan-Xiao
authors.initials: YX
authors.lastname: Li
authors.forename: Jian-Bo
authors.initials: JB
authors.lastname: Ren
authors.forename: Ya-Jun
authors.initials: YJ
authors.lastname: Li
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Guo
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion; D005260:Female; D066298:In Vitro Techniques; D008954:Models, Biological; D012044:Regression Analysis; D012417:Rumen / Q000378:metabolism*; D012418:Ruminants / Q000502:physiology*
chemical_list: D004044:Dietary Proteins