The Large Ruminant Nutrition System (LRNS) to predict nutrient requirements and feed utilization in cattle: History, science, and user guide

This document is the history, science, and user guide of the Large Ruminant Nutrition System (LRNS), version 1.3.1, a Windows program that evaluates and formulates rations for beef and dairy cattle under the conditions of a particular farm: the animals, their environment and management, and the feeds at hand. LRNS implements the Cornell Net Carbohydrate and Protein System (CNCPS) version 5, as published by Fox et al. (2004), with a redesigned interface, corrections, and minor modifications. It was released in November 2009 at Texas A&M University to complement the Small Ruminant Nutrition System, and it preceded the Ruminant Nutrition System (RNS). The first chapter traces the CNCPS from its beginning at Cornell University in 1979, through its use in the Nutrient Requirements of Beef Cattle, to LRNS and the RNS. The second describes the model: its two levels of solution; the requirements for maintenance, growth, pregnancy, lactation, and body reserves; dry matter intake; the carbohydrate and protein fractions of feeds; ruminal fermentation and microbial growth; the supply of metabolizable energy, protein, and amino acids; and the linear and iterative ration optimizer. The third is a user guide to every window of the program, and the fourth works through a feedlot example step by step.