Life Sciences Commons^™

Variance Component Estimates For Growth Traits In Beef Cattle Using Selected Variants From Imputed Low-Pass Sequence Data, Chad A. Russell

Department of Animal Science: Dissertations, Theses, and Student Research

A beef cattle population (n=2,343) was used to assess the impact of variants identified from imputed low-pass sequence (LPS) on the estimation of variance components and genetic parameters of birth weight (BWT) and post weaning gain (PWG). Variants were selected based on functional impact and were partitioned into four groups (Low, Modifier, Moderate, High) based on predicted functional consequences and re-partitioned based on consequence of mutation, such as missense and untranslated region variants, into six groups (G1-G6). Each subset was used to construct a genomic relationship matrix (GRM) for univariate animal models. Multiple analyses were conducted to compare the proportion …

Impact Of Wood-Sourced Biochar On Carbon And Nitrogen Capture In Beef Feedlot Systems, Jessica L. Sperber

Department of Animal Science: Dissertations, Theses, and Student Research

A feedlot growing and finishing experiment evaluated the effect of including pine-sourced biochar at 0.8 (growing) and 1.0% (finishing) of dietary DM on steer performance, carcass characteristics, and greenhouse gas (GHG) production (Exp 1). Two nutrient mass balance experiments were conducted during winter and summer seasons to evaluate the effect of spreading unprocessed red cedar biochar on the feedlot pen surface on manure nutrient capture and cattle performance (Exp 2). In Exp. 1, the inclusion of biochar in the growing diet did not impact steer performance. The inclusion of biochar in the finishing diet significantly reduced intake and gain, resulting …

Host Genetics And Phenotype Associations Within The Bovine Rumen Microbiome, Waseem Abbas

Department of Animal Science: Dissertations, Theses, and Student Research

Rumen microbes have a symbiotic relationship with the host where the host provides a suitable environment and microbial fermentation fulfill nearly 70% of the energy needs of the host. Rumen microbes play a central role in host performance and health. To date, most rumen microbiome studies have focused on the influence of diet on microbial species composition. In addition to dietary factors, studies have suggested that host genetic markers could influence the colonization of gastrointestinal microbiota. However, our understanding of the host-microbiome interaction and how host phenotype is influenced by the rumen microbiome is limited. This dissertation demonstrates: (1) host …

Evaluation Of Alpha Amylase Containing Corn On Beef Cattle Performance And Digestibility And Double-Cropped Annual Forages Following Corn Harvest, Mckenna Brinton

Department of Animal Science: Dissertations, Theses, and Student Research

One digestion and three feedlot trials evaluated the effect of a new corn hybrid containing an α-amylase enzyme trait, Syngenta Enogen Feed Corn (SYT-EFC) on site and extent of digestion, ruminal fermentation parameters, and feedlot performance. Experiments utilized corn containing the enzymatic gene (SYT-EFC) compared to commercially available corn (CON), processed as corn silage (CS) kernel processed or not (KP), dry-rolled corn (DRC), high-moisture corn (HMC), or a blend of DRC and HMC. Growing calves fed high inclusions of CS, displayed increased G:F when CS was KP, resulting in a 6.5% improvement in G:F. Hybrid and kernel processing did not …

Subjective Measures Of Temperament In Beef Heifers Are Reliable Indicators Of Physiological Stress And Indicate Acclimation To Repeated Handling, Jamie Parham

Department of Animal Science: Dissertations, Theses, and Student Research

Associations between excitable temperament and many economically relevant traits have been established. In being heritable, temperament can be augmented through selection. Current methods to evaluate temperament in a production setting include numerous subjective and objective measurements, which some producers may find cumbersome to navigate. Those who utilize these methods may not do so efficiently if selection criteria are not indicative of an animal's response to stress, or initial evaluations are not strong indicators of future temperament. The objectives of this research were to develop a procedure for evaluation of calf behavior, indicative of physiological stress, and then determine whether stress …

Genome-Wide Association Study For Feed Efficiency And Growth Traits In U.S. Beef Cattle, Christopher M. Seabury, David L. Oldeschulte, Mahdi Saatchi, Jonathan E. Beever, Jared E. Decker, Yvette A. Halley, Eric K. Bhattarai, Maral Molael, Harvey Freetly, Stephanie L. Hansen, Helen Yampara-Iquise, Kristen A. Johnson, Monty S. Kerley, Jaewoo Kim, Daniel D. Loy, Elisa Marques, Holly L. Neibergs, Robert D. Schnabel, Daniel W. Shike, Matthew L. Spangler, Bob Weaber, D. J. Garrick, Jeremy F. Taylor

Department of Animal Science: Faculty Publications

Background: Single nucleotide polymorphism (SNP) arrays for domestic cattle have catalyzed the identification of genetic markers associated with complex traits for inclusion in modern breeding and selection programs. Using actual and imputed Illumina 778K genotypes for 3887 U.S. beef cattle from 3 populations (Angus, Hereford, SimAngus), we performed genome-wide association analyses for feed efficiency and growth traits including average daily gain (ADG), dry matter intake (DMI), mid-test metabolic weight (MMWT), and residual feed intake (RFI), with marker-based heritability estimates produced for all traits and populations.

Results: Moderate and/or large-effect QTL were detected for all traits in all populations, as jointly …

Distillers Grains With Solubles For Feedlot Cattle - Finishing Performance, Lipid Metabolism, And Ethanol Greenhouse Gas Balance, Virgil R. Bremer

Department of Animal Science: Dissertations, Theses, and Student Research

Previous University of Nebraska feedlot research trials have characterized the feed value of wet distillers grains plus solubles (WDGS). These trials were summarized with meta-analysis methodology and indicated the feed value of WDGS interacts with corn processing type, cattle age (calf-fed or yearling), and inclusion level. Two steer finishing studies and a metabolism study were conducted to understand the impact of different lipid sources in WDGS on WDGS feed value. A biphasic lipid extraction procedure was developed to analyze feed samples from these trials that was more effective than Goldfisch ether extraction at lipid analysis of byproduct feds. These trials …

Genetic Parameters For Stayability, Stayability At Calving, And Stayability At Weaning To Specified Ages For Hereford Cows, G. E. Martinez, R. M. Koch, L. V. Cundiff, K. E. Gregory, Stephen D. Kachman, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Genetic parameters for stayability to six ages (ST1, . . ., ST6), for five measures of stayability to calving (SC2, . . ., SC6), and for five measures of stayability to weaning (SW2, . . ., SW6), were estimated using records of 2,019 Hereford cows collected from 1964 to 1979 from a selection experiment with a control line and three lines selected for weaning weight, yearling weight, and an index of yearling weight and muscle score. The model included birth year of the cow as a fixed effect and the cow’s sire as a random effect. Analyses were performed with …

Genetic Analysis Of Carcass Traits Of Steers Adjusted To Age, Weight, Or Fat Thickness Slaughter Endpoints, A. Rios-Utrera, L. V. Cundiff, K. E. Gregory, R. M. Koch, M. E. Dikeman, M. Koohmaraie, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Carcass measurements from 1,664 steers from the Germ Plasm Utilization project at U.S. Meat Animal Research Center were used to estimate heritabilities (h²) of, and genetic correlations (r_g) among, 14 carcass traits adjusted to different endpoints (age, carcass weight, and fat thickness): HCW (kg), dressing percent (DP), adjusted fat thickness (AFT, cm), LM area (LMA, cm²), KPH (%), marbling score (MS), yield grade (YG), predicted percentage of retail product (PRP), retail product weight (RPW, kg), fat weight (FW, kg), bone weight (BNW, kg), actual percentage retail product (RPP), fat percent (FP), and bone percent. …

Evaluation Of Grazing Alternate Summer And Fall Forages In Extensive Beef Cattle Production Systems, D. H. Shain, T. J. Klopfenstein, R. A. Stock, B, A. Vieselmeyer, G. E. Erickson

Department of Animal Science: Faculty Publications

Studies across 5 yr involving 938 British-breed crossbred cattle (372 heifers, 566 steers) were used to evaluate the effects of grazing alternate summer and fall forages on slaughter breakeven cost of various beef production systems. Grazed summer forage combinations included 1) continuous brome, 2)brome and warm-season grasses, 3) brome and alfalfa or sudangrass, 4) brome and a monoculture of red clover, 5) red clover seeded in brome, 6) brome and Native Sandhills range, or 7) Sandhills range only. Grazed fall forages included 1) brome, 2) brome and turnips, 3) brome and rye, or 4) brome and cornstalks. Following grazing, the …

Genetic Relationships Between Male And Female Reproductive Traits In Beef Cattle, G. Gargantini, L. V. Cundiff, D. D. Lunstra, L. D. Van Vleck

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Reproductive traits were measured for 234 bulls and 1184 heifers from matings of three dam breeds (Angus, Hereford, and U.S. Meat Animal Research Center III) with six sire breeds (Angus, Hereford, Brahman, Boran, Tuli, and Belgian Blue) from the Germ Plasm Evaluation (GPE) Program at Roman L. Hruska US Meat Animal Research Center. Male traits were yearling scrotal circumference (YSC), height (YH), and yearling BW; age at puberty (AP1; production of 50 million sperm with ≥10% progressive motility); age, scrotal circumference, average testis length, and testicular volume when 500 million sperm were …

Optimal Wet Corn Gluten And Protein Levels In Steam-Flaked Corn-Based Finishing Diets For Steer Calves, H. C. Block, C. N. Macken, Terry Klopfenstein, Galen E. Erickson, Rick Stock

Department of Animal Science: Faculty Publications

A feeding trial evaluated the hypothesis that wet corn gluten feed would improve growth performance of cattle fed steam-flaked corn-based finishing diets and supply required degradable intake protein (DIP). The trial used 360 steer calves (initial BW = 288 ± 11 kg) housed in 36 pens for 166 d in an incomplete 4 × 3 factorial arrangement of treatments. Pens of steers were assigned to treatments according to a completely randomized design (four replicates per treatment combination). Treatments were wet corn gluten feed (0, 20, 30, or 40% of dietary DM) and CP (13.0, 13.7, or 14.4% of dietary DM) …

Genetic Parameters For Six Measures Of Length Of Productive Life And Three Measures Of Lifetime Production By 6 Yr After First Calving For Hereford Cows, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Genetic parameters for length of productive life given the opportunity (LPL|O), measured as days between first calving and disposal conditioned on one of six opportunity groups, L1 through L6 (e.g., L2 is length of productive life in days given the opportunity to live 2 yr after first calving), and lifetime production (LP), measured as the number of calves born (NB), number of calves weaned (NW), and cumulative weaning weight (CW) by 6 yr after first calving, were estimated using records of 1,886 Hereford cows from a selection experiment with three selected lines and a control line. Weaning weights were adjusted …

Number Of Calves Born, Number Of Calves Weaned, And Cumulative Weaning Weight As Measures Of Lifetime Production For Hereford Cows, G. E. Martinez, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Genetic parameters for lifetime production for cows with the opportunity to produce from 2 through 7 yr of age, as measured by the number of calves born (NB2, …, NB7), the number of calves weaned (NW2, …, NW7), and cumulative weaning weight (CW2,…, CW7), were estimated using data from 3,064 Hereford cows from a selection experiment with a control line (CTL) and three lines selected for weaning weight (WWL), yearling weight (YWL), and an index of yearling weight and muscle score (IXL). Weaning weights were adjusted to 200 d of age and for sex and age of dam. Estimates of …

Genetic Response To Selection For Weaning Weight Or Yearling Weight Or Yearling Weight And Muscle Score In Hereford Cattle: Efficiency Of Gain, Growth, And Carcass Characteristics, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

An experiment involving crosses among selection and control lines was conducted to partition direct and maternal additive genetic response to 20 yr of selection for 1) weaning weight, 2) yearling weight, and 3) index of yearling weight and muscle score. Selection response was evaluated for efficiency of gain, growth from birth through market weight, and carcass characteristics. Heritability and genetic correlations among traits were estimated using animal model analyses. Over a time-constant interval, selected lines were heavier, gained more weight, consumed more ME, and had more gain/ME than the control. Over a weight-constant interval, selected lines required fewer days, consumed …

Effect Of Organic Matter Addition To The Pen Surface And Pen Cleaning Frequency On Nitrogen Mass Balance In Open Feedlots, J. R. Adams, T. B. Farran, Galen Erickson, Terry Klopfenstein, C. N. Macken, C. B. Wilson

Department of Animal Science: Faculty Publications

Three finishing trials were conducted to determine the effects of dietary manipulation and management on N losses from open feedlots. In each experiment, 96 steers were assigned randomly to 12 nutrient balance pens. In Trial 1, calves were fed for 180 d during the winter/spring months; in Trial 2, yearlings were fed for 132 d in the summer. In Trials 1 and 2, N losses from pens were compared directly by adding OM to the pen surface or indirectly by feeding digestible ingredients designed to increase OM excretion. The dietary treatment (BRAN) included 30% corn bran (DM basis) replacing dry-rolled …

Fat Supplementation And Reproduction In Beef Females, Richard N. Funston

Department of Animal Science: Faculty Publications

Inadequate dietary energy intake and poor body condition can negatively affect reproductive function. Supplemental lipids have been used to increase energy density of the diet and may also have direct positive effects on reproduction in beef cattle. Several fatty acid sources have been studied as they relate to reproductive function. Common sources include sunflower, safflower, cottonseed, rice bran, soybeans, fishmeal, animal tallow, and calcium salts of fatty acids. Fats have been fed before and after calving, during the breeding season, and during heifer development. Response to fat has been investigated through measuring body weight and body condition score, age at …

Review: Re-Evaluation Of Phosphorus Requirements And Phosphorus Retention Of Feedlot Cattle, H. C. Block, G. E. Erickson, T. J. Klopfenstein

Department of Animal Science: Faculty Publications

Phosphorus requirement recommendations for cattle are important for preventing over-feeding of P and excessive P excretion. Improved precision in managing P nutrition can reduce feedlot waste management concerns. Current beef recommendations (NRC, 1996) fail to account for absorption coefficient variation related to P source, whereas dairy recommendations (NRC, 2001) change absorption coefficients with P source. Maintenance and BW gain requirements for absorbed P do not represent underlying relationships. Maintenance P requirements reflect endogenous P loss arising from failure to reabsorb salivary P. Basing maintenance requirements on saliva P secretion and re-absorption rates should improve precision of maintenance requirement estimates. Gain …

Comparisons Of Angus, Charolais, Galloway, Hereford, Longhorn, Nellore, Piedmontese, Salers, And Shorthorn Breeds For Weight, Weight Adjusted For Condition Score, Height, And Condition Score Of Cows, Jesus Arango, L. V. Cundiff, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Breed differences for weight (CW), height (CH), and condition score (CS) were estimated from records (n &#;&#;12,188) of 2- to 6-yr-old cows (n &#; 744) from Cycle IV of the U.S. Meat Animal Research Center’s Germplasm Evaluation (GPE) Program. Cows were produced from mating Angus and Hereford dams to Angus, Hereford, Charolais, Shorthorn, Galloway, Longhorn, Nellore, Piedmontese, and Salers sires. Samples of Angus and Hereford sires were 1) reference sires born from 1962 through 1970 and 2) 1980s sires born in 1980 through 1987. The mixed model included cow age, season of measurement and their interactions, year of birth, pregnancy-lactation …

Covariance Functions And Random Regression Models For Cow Weight In Beef Cattle, Jesus Arango, L. V. Cundiff, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Data from the first four cycles of the Germplasm Evaluation program at the U.S. Meat Animal Research Center were used to evaluate weights of Angus, Hereford, and F1 cows produced by crosses of 22 sire and 2 dam (Angus and Hereford) breeds. Four weights per year were available for cows from 2 through 8 yr of age (AY) with age in months (AM). Weights (n &#;&#;61,798) were analyzed with REML using covariance function-random regression models (CF-RRM), with regression on orthogonal (Legendre) polynomials of AM. Models included fixed regression on AM and effects of cow line, age in years, season of …

Genetic Relationships Between Scrotal Circumference And Female Reproductive Traits, G. Martinez-Valezquez, K. E. Gregory, G. L. Bennett, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Records for yearling scrotal circumference (SC; n = 7,580), age at puberty in heifers (AP; n = 5,292), age at first calving (AFC; n = 4,835), and pregnancy, calving, or weaning status following the first breeding season (PR1, CR1, or WR1, respectively; n = 7,003) from 12 Bos taurus breeds collected at the Meat Animal Research Center (USDA) between 1978 and 1991 were used to estimate genetic parameters. Age at puberty (AP) was defined as age in days at first detected ovulatory estrus. Pregnancy (calving or weaning) status was scored as one for females conceiving (calving or weaning) given exposure …

Effects Of Final Implant Type And Supplementation Of Melengestrol Acetate® On Finishing Feedlot Heifer Performance, Carcass Characteristics, And Feeding Economics1, C. N. Macken, C. T. Milton, T. J. Klopfenstein, B, D, Dicke, D. E. Mcclellan

Department of Animal Science: Faculty Publications

Three finishing experiments were conducted in commercial feedlots to determine effects of implant programs on finishing heifer performance, carcass characteristics, and economics. A total of 3,307 heifers were used in the three experiments. Overall, four treatment comparisons were tested within the three separate experiments. Treatment groups included the following: 1) heifers implanted with Synovex® Plus (Fort Dodge Animal Health; Fort Dodge, IA) but not fed melengestrol acetate (MGA®; Pharmacia and Upjohn Company; Kalamazoo, MI) , 2) heifers implanted with Synovex® Plus and fed MGA®, 3) heifer implanted with Revalor®-H (Intervet Inc.; Millsboro, DE) and fed MGA®, and 4) …

Breed Comparisons Of Angus, Charolais, Hereford, Jersey, Limousin, Simmental, And South Devon For Weight, Weight Adjusted For Body Condition Score, Height, And Body Condition Score Of Cows, Jesus Arango, L. V. Cundiff, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Breed means and differences for weight (CW, n = 19,851), height (CH, n = 14,553), and condition scores (CS, n = 19,536) recorded in four seasons per year were evaluated for 881 cows ranging from 2 to 7 yr of age from Cycle I of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center. Cows were straightbred Herefords and Angus and top-crosses from mating of Hereford, Angus, South Devon, Jersey, Simmental, Limousin, and Charolais sires to Hereford and Angus dams. The model included cow age, season of measurement, and their interactions, with year of birth, pregnancy-lactation (PL) code, …

Comparisons Of Angus-, Braunvieh-, Chianina-, Hereford-, Gelbvieh-, Maine Anjou-, And Red Poll-Sired Cows For Weight, Weight Adjusted For Body Condition Score, Height, And Body Condition Score, Jesus Arango, L. V. Cundiff, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Data from Angus, Hereford, and topcross cows (n = 641) from 2- to 8-yr-old daughters of seven breeds of sires included in Cycle II of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center, comprising cow weight (CW, n = 15,698), height (CH, n = 15,676), and condition score (CS, n = 15,667), were used to estimate breed-group differences. Data were recorded in four seasons of each year (1975 to 1982). The mixed model included cow age, season of measurement, and their interactions, year of birth, pregnancy-lactation code (PL), and breed-group as fixed effects for CW and CS. …

Breed Comparisons Of Angus, Brahman, Hereford, Pinzgauer, Sahiwal, And Tarentaise For Weight, Weight Adjusted For Condition Score, Height, And Body Condition Score, Jesus Arango, L. V. Cundiff, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Data from topcross cows (n = 468) from six breeds of sire (Angus, Brahman, Hereford, Pinzgauer, Sahiwal, Tarentaise) and two breeds of dam (Angus and Hereford) of Cycle III of the Germplasm Evaluation (GPE) program at the U.S. Meat Animal Research Center (MARC) comprising cow weight (CW, n = 9,012), height (CH, n = 9,010), and condition score (CS, n = 8,991) recorded in four seasons per year from 2 to 6 yr of age were used to estimate breed-group differences. The mixed models included cow age, season of measurement and their interactions, year of birth, pregnancy-lactation code (PL), and …

Comparison Of Models For Estimation Of Genetic Parameters For Mature Weight Of Hereford Cattle, J. M. Rumph, R. M. Koch, K. E. Gregory, L. V. Cundiff, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Genetic parameters of mature weight are needed for effective selection and genetic evaluation. Data for estimating these parameters were collected from 1963 to 1985 and consisted of 32,018 mature weight records of 4,175 Hereford cows that were in one control and three selection lines that had been selected for weaning weight, for yearling weight, or for an index combining yearling weight and muscle score for 22 yr. Several models and subsets of the data were considered. The mature weight records consisted of a maximum of three seasonal weights taken each year, at brand clipping (February and March), before breeding (May …

Utilization Of Distillers Grains Form The Fermentation Of Sorghum Or Corn In Diets For Finishing Beef And Lactating Dairy Cattle, S. Al-Suwaiegh, K. Fanning, R. J. Grant, C. T. Milton, Terry J. Klopfenstein

Department of Animal Science: Faculty Publications

Beef finishing and dairy lactation experiments were conducted to evaluate the nutritional value of distillers grains (DG) from sorghum or corn fermentation, in both wet (35.4% DM) and dry (92.2% DM) form (dairy trial only). In the finishing experiment, 60 yearling steers were used in a completely randomized design with three diets that were fed for 127 d: 1) control diet with 86% (DM basis) dry-rolled corn and no DG; 2) 30% of ration DM as wet corn DG in place of dry-rolled corn; and 3) 30% of ration DM as wet sorghum DG in place of dry-rolled corn. All …

Parameter Estimates For Direct And Maternal Genetic Effects On Yearling, Eighteen-Month, And Slaughter Weights Of Korean Native Cattle, J. W. Lee, S. B. Choi, Y. H. Jung, Jeffrey F. Keown, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Data collected by the National Livestock Research Institute of the Rural Development Administration of Korea were used to estimate genetic parameters for yearling (YWT, n = 5,848), 18-mo (W18, n = 4,585), and slaughter (SWT, n = 2,279) weights for Korean Native cattle. Nine animal models were used to obtain REML estimates of genetic parameters: DP- 2 included genetic, uncorrelated dam, and residual random effects; DQ-2 included genetic, sire × region × year-season interaction, and residual random effects; DPQ- 2 was based on DQ-2 but included both interaction and dam effects; DMP-2 was based on DP-2 but with dam effect …

Parameter Estimates For Genetic Effects On Carcass Traits Of Korean Native Cattle, J. W. Lee, S. B. Choi, J. S. Kim, Jeffrey F. Keown, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Data (n = 1,746) collected from 1985 through 1995 on Korean Native Cattle by the National Livestock Research Institute of Korea were used to estimate genetic parameters for marbling score, dressing percentage, and longissimus muscle area, with backfat thickness, slaughter age, or slaughter weight as covariates. Estimates were obtained with REML. Model 1 included animal genetic and residual random effects. Model 2 was extended to include an uncorrelated random effect of the dam. Model 3 was based on Model 1 but also included sire × region × year-season interaction effects. Model 4 combined Models 2 and 3. All models included …

Designing And Conducting Experiments For Range Beef Cows, Don C. Adams, Merlyn K. Nielsen, Walter H. Schacht, Richard T. Clark

Department of Animal Science: Faculty Publications

Designing and conducting effective research for range beef systems involves analysis of intended application of the results, identification of factors affecting variation, and selection of appropriate research methods so that precise inferences can be made. Variances associated with time, location, animal, and error in grazing research can be high. Variation due to treatment × location and treatment × time interactions is reduced by increasing the number of locations and periods tested. Random error is reduced by increasing the total number of observations. Animals, pastures, and weather are significant sources of variation in grazing studies. Factors that influence nutrient requirements or …