Managing N Inputs and the Effect on N Losses Following Excretion in Open-Dirt Feedlots in Nebraska

Feedlot nutrition will play an important role in meeting environmental challenges of beef cattle feedlots. Nutritionists are continually refining protein requirements and recently adopted a new, metabolizable protein (MP) system to more efficiently use N and allow more accurate diet formulation. Protein requirements vary by animal age and weight during the finishing period. Our hypothesis was that formulating diets with the MP system would decrease N inputs leading to decreased excretion and losses. Comparing industry average diets (13.5% CP) to phase-fed diets formulated to not exceed MP requirements decreased N inputs by 10 to 20% for calves and yearlings without affecting ADG. Decreasing inputs led to a concomitant decrease in N excretion (12-21%) and losses (15 to 33%) in open-dirt feedlot pens. Nitrogen losses are variable with time of year, with averages of 60 to 70% of excreted N lost during the summer months and 40% lost from November to May feeding periods. Protein requirements are being refined continually as more research data are collected. However, formulation to meet, but not exceed, protein requirements is an important nutritional management option for feedlots to become sustainable

G84-693 Protein Levels for Growing and Finishing Cattle

This NebGuide describes the use of nonprotein nitrogen and bypass protein sources to fulfill the protein requirements of growing and finishing steers, heifers and bulls. Protein supplementation can be an expensive feed cost for cattle producers. Through the use of nonprotein nitrogen (NPN) and bypass protein sources, however, these costs can be reduced. Bypass protein is the protein that escapes breakdown in the rumen and passes as is into the small intestine where it is digested and absorbed. Because NPN sources are usually the most economical sources of supplemental nitrogen, NPN should be used whenever possible. The potential for using NPN depends on the ability of the rumen microorganisms to synthesize protein, the bypass protein supplied by ration ingredients, and the protein requirement of the animal

Cysteine from Feather Meal And Sulfur Amino Acid Requirements for Growing Steers

Ninety individually fed steers were used to determine how cysteine from feather meal could replace dietary methionine in meeting their requirements for sulfur amino acids. Treatment proteins included blood meal, blood meal plus incremental levels of feather meal or blood meal plus incremental levels of rumen-protected methionine. Addition of sulfur amino acids to blood meal from feather meal or rumen-protected methionine improved average daily gain (P \u3c .05). Rumen-protected methionine elicited a greater gain response than feather meal (P \u3c .05). Feather meal can provide some of the sulfur amino acids lacking in blood meal. However, additional methionine may further improve performance

Wheat Straw, Distillers Grains, and Beet Pulp for Late Gestation Beef Cows

The feeding value of a mixture of 30:70 wet distillers grains:wheat straw or 20:20:60 wet distillers grains:beet pulp:wheat straw (DM) for late gestation beef cows was estimated. In Experiment 1, cows limit fed distillers grains and wheat straw gained as much weight and body condition as cows limit fed alfalfa hay. In Experiment 2, cows fed wet distillers grains and wheat straw or wet distillers grains, beet pulp, and wheat straw gained more weight and improved body condition compared with cows fed alfalfa hay. The results of these experiments indicate cows in late gestation will maintain body condition when limit fed by-products and crop residues to meet their energy requirements

Determinants of Profit Variability in Calf-Fed and Yearling Production Systems

Factors that were determinants of profit variability in calf-fed and yearling beef production systems were identified and ranked. The analysis indicated cattle prices have the greatest influence on profit variation for both systems and on all backgrounding and finishing phases of the yearling system. Prices of feedstuffs (i.e., corn prices, wet corn gluten feed prices, and pasture and cornstalk rental rates) were the next most important factors explaining profit risk. Cattle performance variables and interest rates had the smallest impact on profit variation

Wheat Straw, Distillers Grains, and Beet Pulp for Late Gestation Beef Cows

The feeding value of a mixture of 30:70 wet distillers grains:wheat straw or 20:20:60 wet distillers grains:beet pulp:wheat straw (DM) for late gestation beef cows was estimated. In Experiment 1, cows limit fed distillers grains and wheat straw gained as much weight and body condition as cows limit fed alfalfa hay. In Experiment 2, cows fed wet distillers grains and wheat straw or wet distillers grains, beet pulp, and wheat straw gained more weight and improved body condition compared with cows fed alfalfa hay. The results of these experiments indicate cows in late gestation will maintain body condition when limit fed by-products and crop residues to meet their energy requirements

Determinants of Profit Variability in Calf-Fed and Yearling Production Systems

Factors that were determinants of profit variability in calf-fed and yearling beef production systems were identified and ranked. The analysis indicated cattle prices have the greatest influence on profit variation for both systems and on all backgrounding and finishing phases of the yearling system. Prices of feedstuffs (i.e., corn prices, wet corn gluten feed prices, and pasture and cornstalk rental rates) were the next most important factors explaining profit risk. Cattle performance variables and interest rates had the smallest impact on profit variation

Effects of Manipulating Protein and Phosphorus Nutrition of Feedlot Cattle on Nutrient Management and the Environment

Feedlot nutrition will play a role in meeting challenges such as nutrient management. Nitrogen and phosphorus are two nutrients that are currently studied in this context. One nutritional method is formulating diets not to exceed requirements for nitrogen and phosphorus. Requirements are different for calves and yearlings. The requirements also change during the finishing period. Phosphorus requirements have not been extensively studied for feedlot cattle between 270 and 600 kg. Therefore, P requirements studies were conducted to determine the P requirement of calves (265 kg) and yearlings (385 kg). The requirement was not detected with P levels as low as 0.14 (yearlings) and 0.16% (calves) of diet DM based on performance and bone ash. Compared to NRC-predicted P requirements, P intakes ranged from 76 to 190% (calves) and 71 to 162% (yearlings). In separate nutrient balance experiments, decreasing dietary P to NRC-predicted requirements (0.22 to 0.28%) did not influence gain but decreased P input by 33 to 45% and excretion by 40 to 50% compared to the industry average (0.35% P). The metabolizable protein (MP) system was recently adopted and may allow more accurate diet formulation for protein, thereby decreasing N excretion. Compared to the industry average (13.5% CP) and formulation with the CP system, using the NRC model and phase-feeding not to exceed MP requirements over the feeding period decreased N inputs by 10 to 20% for calves and yearlings without affecting ADG. Decreasing N inputs led to a concomitant decrease in N excretion (12 to 21%) and volatilization (15 to 33%) in open-dirt feedlot pens. Nitrogen losses are variable with time of year, with averages of 60 to 70% of excreted N lost during the summer months and 40% lost from November to May feeding periods. Protein requirements are continually being refined as more research data are collected. However, formulation to meet and not exceed protein requirements and removal of P supplements are important nutritional management options to help feedlots become more environmentally sustainable

Effects of Manipulating Protein and Phosphorus Nutrition of Feedlot Cattle on Nutrient Management and the Environment

Feedlot nutrition will play a role in meeting challenges such as nutrient management. Nitrogen and phosphorus are two nutrients that are currently studied in this context. One nutritional method is formulating diets not to exceed requirements for nitrogen and phosphorus. Requirements are different for calves and yearlings. The requirements also change during the finishing period. Phosphorus requirements have not been extensively studied for feedlot cattle between 270 and 600 kg. Therefore, P requirements studies were conducted to determine the P requirement of calves (265 kg) and yearlings (385 kg). The requirement was not detected with P levels as low as 0.14 (yearlings) and 0.16% (calves) of diet DM based on performance and bone ash. Compared to NRC-predicted P requirements, P intakes ranged from 76 to 190% (calves) and 71 to 162% (yearlings). In separate nutrient balance experiments, decreasing dietary P to NRC-predicted requirements (0.22 to 0.28%) did not influence gain but decreased P input by 33 to 45% and excretion by 40 to 50% compared to the industry average (0.35% P). The metabolizable protein (MP) system was recently adopted and may allow more accurate diet formulation for protein, thereby decreasing N excretion. Compared to the industry average (13.5% CP) and formulation with the CP system, using the NRC model and phase-feeding not to exceed MP requirements over the feeding period decreased N inputs by 10 to 20% for calves and yearlings without affecting ADG. Decreasing N inputs led to a concomitant decrease in N excretion (12 to 21%) and volatilization (15 to 33%) in open-dirt feedlot pens. Nitrogen losses are variable with time of year, with averages of 60 to 70% of excreted N lost during the summer months and 40% lost from November to May feeding periods. Protein requirements are continually being refined as more research data are collected. However, formulation to meet and not exceed protein requirements and removal of P supplements are important nutritional management options to help feedlots become more environmentally sustainable

Evaluation of Feather Meal as a Source of Sulfur Amino Acids for Growing Steers

In situ and digestion studies were conducted to evaluate feather meal (FTH), blood meal (BM), and meat and bone meal (MBM) for escape protein content, amino acid composition of the escape protein, true protein digestibility, and digestibility of the individual amino acids. Following 12 h of ruminal incubation, escape protein values were 73.5, 92.4, and 60.8% of CP for FTH, BM, and MBM, respectively. Blood meal and MBM were poor sources of sulfur amino acids (SAA), whereas FTH was a good source. Most of the SAA of FTH, however, was Cys, with very little Met. True protein digestibilities were not different for the protein sources (P \u3e .15), ranging from 86.7 to 94.0% of the CP. However, digestibilities of the individual amino acids were quite different. Two growth studies were conducted to evaluate FTH as a source of SAA for growing cattle. The first study used 120 steers (228 ± 15 kg) supplemented with urea, MBM, MBM plus 1% FTH, or MBM plus 2% FTH. Additionally, incremental amounts of rumen-protected Met were added to treatments containing MBM. Supplementation of MBM increased (P \u3c .05) ADG compared with the urea control. Addition of FTH to MBM resulted in a linear (P \u3c .01) increase in ADG. However, addition of rumen-protected Met to MBM plus FTH treatments further improved gains. Although FTH is an effective source of SAA, Met probably was first-limiting. The second study used 90 steers (243 ± 18 kg) supplemented with BM plus incremental amounts of SAA from either FTH or rumen-protected Met. Addition of SAA improved ADG compared with BM alone (P \u3c .05). Rumen-protected Met as a source of SAA improved ADG compared with FTH (P \u3c .05). The SAA from FTH promoted a gain response equal to 50% of the response obtained with rumen-protected Met. Formulation of ruminant diets for metabolizable amino acids must account for escape value and digestibility of each individual amino acid. Feather meal is an effective source of SAA; however, Cys supplies over five times the amount supplied by Met