Determination of the optimal rate and efficiency of nitrogen usage in cattle.
Abstract
The objective of this study was to examine the effects of feeding increasing amounts of an 'amino acid-balanced' combination of animal by-product protein sources on rate and efficiency of N retention in growing cattle. The 1996 NRC model was used to formulate a corn-based (86:14 concentrate-hay) control diet to allow, based on the supply of ME and MP, for an ADG of 1.4 kg in 250 kg steers with an estrogenic implant and fed an ionophore. The model was then used to formulate an undegradable intake protein (UIP) mix containing pork meal, blood meal, fish meal and hydrolyzed feather meal that would provide an optimal amino acids spectrum. Four steers were assigned in a 4 x 4 Latin square design to treatments consisting of three levels of UIP administration (0, 2.6%, and 5.2% of the total DM) as well as a 'urea-diet' containing no soybean meal and no UIP mix. All four diets were formulated to fulfill the N requirements of the rumen and to provide ME and MP in amounts allowing roughly the same ADG. Diets contained approximately 13.9, 14.6, 15.3, 13.4% CP on a DM basis, respectively. N intake was 145 g/d for the 'urea diet' and increased from 155 to 162 g/d as % UIP increased from 0 to 5.2%. N digestibility was not affected, but urinary N excretion was significantly greater when the 5.2 % UIP diet was fed. Only the 5.2% UIP diet resulted in a significant reduction of N retention and efficiency of N usage. Biological values were 46, 46 and 45% for the 2.6% UIP, 'urea' and the control diet, respectively. The use of 5.2% UIP in the diet reduced (P<.05) the biological value to 38 %, indicated also by a significant elevation of the plasma urea N. Results demonstrate that feeding small amounts of a mixture of UIP sources, formulated to improve amino acid balance and increase total mass of absorbed N, elevate N retention and optimize biological value of absorbed N in growing cattle.
keywords cattle protein intake urea nitrogen balance
Publikationen
Recent developments in understanding the protein and amino acid requirements of ruminants.
Autoren: Beermann, D. H., Knaus, W. F., Robinson, T. F., Fox, D. G. Jahr: 1999
Conference & Workshop proceedings, paper, abstract
Optimization of rate and efficiency of dietary nitrogen utilization through the use of animal by-products and(or) urea and their effects on nutrient digestion in Holstein steers.
Autoren: Knaus, W.F., Beermann, D.H., Guiroy, P.J., Boehm, M.L., Fox, D.G. Jahr: 2001
Journal articles
Dietary protein utilization in Holstein steers fed a corn-based diet supplemented with different amounts and forms of nitrogen.
Autoren: Knaus, W.F., Beermann, D.H., Tedeschi, L.O.,Czajkowski, M., Fox, D.G., Russell, J.B. Jahr: 2001
Conference & Workshop proceedings, paper, abstract
Effects of dietary urea and estradiol-17? on the efficiency of nitrogen usage in growing Holstein steers fed a diet based on low-quality grass hay.
Autoren: Knaus, W.F., Beermann, D.H., Tedeschi, L.O., Guiroy, P.J., Boehm, M.L., Fox, D.G. Jahr: 2001
Conference & Workshop proceedings, paper, abstract
Effects of urea, isolated soybean protein and blood meal on growing steers fed a corn-based diet
Autoren: Knaus, W.F., Beermann, D.H., Tedeschi, L.O., Czajkowski, M., Fox, D.G., Russell, J.B. Jahr: 2002
Journal articles
Project staff
Wilhelm Friedrich Knaus
Ao.Univ.Prof. Dipl.-Ing. Dr.nat.techn. Wilhelm Friedrich Knaus
wilhelm.knaus@boku.ac.at
Tel: +43 1 47654-93235
Project Leader
01.08.1998 - 31.07.1999
BOKU partners
External partners
Cornell University
none
coordinator