Intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage and supplemented with nitrogen and different levels of starch
Open Access
- 28 October 2016
- journal article
- Published by Asian Australasian Association of Animal Production Societies in Asian-Australasian Journal of Animal Sciences
- Vol. 30 (6), 797-803
- https://doi.org/10.5713/ajas.16.0629
Abstract
Effects of nitrogen supplementation associated with different levels of starch on voluntary intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage (Brachiaria decumbens hay, 7.4% crude protein, CP) were evaluated using ruminal and abomasal cannulated steers. Five European×Zebu young bulls (186 kg body weight, BW) were distributed according to a 5×5 Latin square. The following treatments were evaluated: control, supplementation with 300 g CP/d (0:1), supplementation with 300 g starch/d and 300 g CP/d (1:1), supplementation with 600 g starch/d and 300 g CP/d (2:1), and supplementation with 900 g starch/d and 300 g CP/d (3:1). A mixture of nitrogenous compounds provided 1/3 from true protein (casein) and 2/3 from non-protein nitrogen (mixture of urea and ammonium sulphate, 9:1) was used as the nitrogen supplement. In order to supply energy a unique source of corn starch was used. Supplements increased (p0.05) forage intake. There was a cubic effect (p0.05) neutral detergent fibre corrected for ash and protein (NDFap) digestibility. There was a positive linear effect (p0.05) by the amount of supplemental starch. Ruminal ammonia nitrogen concentrations were higher (p<0.05) in supplemented animals, however, a negative linear effect (p<0.05) of amount of starch was observed. Supplements increased (p<0.05) the nitrogen balance (NB) and efficiency of nitrogen utilization. These effects were attributed to increased body anabolism, supported by higher (p<0.05) serum concentration of insulin-like growth factor 1. Increasing the amount of starch tended (p<0.06) to linearly increase the NB. In spite of this, there was a highest NB value for the 2:1 starch:CP ratio amongst the treatments with supplementation. Nitrogen supplementation in cattle fed low-quality tropical forage increases nitrogen retention in the animal’s body. An additional supply of starch increases nitrogen retention by increasing energy availability for both rumen and animal metabolism.Keywords
Funding Information
- Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico
- Fundação de Amparo a Pesquisa de Minas Gerais
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