In addition to dose-response studies, modeling of N utilization, depending on intake of the first limiting amino acid in the diet, is one of the tools for assessing amino acid requirements in growing animals. Based on a verified nonlinear N-utilization model and following the principles of the diet dilution technique, N-balance experiments were conducted to estimate the Thr requirement of fast-...

Feed intake, feed efficiency, and weight gain are important economic traits of beef cattle in feedlots. In the present study, we investigated the physiological processes underlying such traits from the point of view of systems genetics. Firstly, using data from 1334 Nellore (Bos indicus) cattle and 943,577 single nucleotide polymorphisms (SNPs), a genome-wide association analysis was performed ...

(allowed to eat according to appetite). Generally, this allows for maximum performance because energy consumed above the maintenance requirement is available for gain. However, recent work suggests that limit-fed animals may have better feed efficiency. This has economic importance in that changes in feed efficiency have three times the impact on cost of gain as an equal change in rate of gain....

Net feed intake (NFI) is a moderately heritable feed efficiency trait that has been shown to be genetically independent of ADG and BW in beef cattle. Objectives of this study were to characterize NFI in growing bulls, and to examine phenotypic correlations between NFI and performance, body composition, and fertility traits. Net feed intake was positively correlated phenotypically with feed conv...

an experiment was conducted to evaluate the effect of withdrawing vitamin and/or trace mineral premixes from grower and finisher diets of broilers. a 2×4 factorial arrangement of treatments, consisting of four diets and two-removal times (from 28 to 49, and from 35 to 49 days of age) was utilized. the four diets consisted of control, supplemented with vitamin (vit) and trace minerals (tm)(t1); ...

Interest in improving feed efficiency in cattle is intensifying. Residual feed intake (RFI), which is the difference between expected intake and that predicted based on energy demands, is now the most commonly used measure of feed efficiency over a given time period. However, RFI, as commonly defined, is independent of growth rate, which may affect its acceptance by industry. Residual BW gain (...

The objective of this study was to evaluate the performance of male broiler chickens in the period from 21 to 42 days of age fed diets with increasing levels of sunflower meal (SM) supplemented with an enzyme complex (EC). A total of 1920 animals of the Cobb strain were distributed in a randomized block design in a 4 × 3 factorial arrangement (four SM levels and three enzymes utilization types)...

Feed intake and efficiency are economically important traits because feed is the greatest variable cost in beef production. Feed efficiency can be measured as residual feed intake (RFI), which is the difference between actual DMI of an animal and the expected DMI based on its BW and growth rate. Feed conversion ratio (FCR) is the inverse of gross feed efficiency and is the ratio of DMI to ADG. ...

The beef industry in the United States is developing programs to minimize excess fat produced, increase consistency of product and to identify and reward individual owners for superior performance in the feedlot. In the U.S., Strategic Alliances between cow-calf, feedlot and packer segments of the industry are being developed to accomplish this goal. Integrated production and marketing systems ...