Red Angus Bulls Research Articles

PSX-23 Effects of Partial Or Total Nitrogen Replacement of Soybean Meal with Urea on Intake, Digestibility and Nitrogen Balance in Growing Nellore × Red Angus Bulls

Abstract In feedlot systems, feeding non-protein nitrogen sources, such as urea, instead of true protein sources, such as soybean meal (SBM), could be an alternative way to reduce dietary costs. This study aimed to evaluate the effects of partial or total replacement of SBM by urea on feed intake and apparent total-tract digestibility of organic matter (OM) and crude protein (CP), and on nitrogen (N) balance in bulls. Four Nellore × Red Angus crossbred bulls (292 ± 14.6 kg BW) were randomly assigned to treatment in a 4×4 Latin square design. The experimental treatments consisted of different replacement levels of SBM by urea (DM basis): 0% replacement (R-0%); 54% replacement (R-54%); 78% replacement (R-78%); 100% replacement (R-100%). Diets were formulated according to the BR-CORTE system to provide approximately 130 g CP/kg DM. The diets consisted of 20% corn silage and 80% ground corn-based concentrate containing SBM and/or urea+ammonium sulfate, mineral mix, and virginiamycin. Each experimental period was 21 d, with 14 d adaptation, and 4 d of total feces and urine collection. Data were analyzed using the MIXED procedure in SAS and statistical significance was declared at P < 0.05. Dietary treatment did not influence (P > 0.05) OM and CP intake. Apparent total-tract OM and CP digestibility were not influenced (P > 0.05) by dietary treatment. Daily total urinary and fecal N were not influenced (P > 0.05) by dietary treatment. Dietary treatment did not influence (P > 0.05) N retention. Therefore, these data suggest that SBM may be partially or totally replaced by urea as the dietary N source without affecting feed intake, apparent total-tract digestibility, and N balance in Nellore × Red Angus crossbreed young bulls fed a high concentrate diet.

179 An Evaluation of Oklahoma Beef Calf Market Characteristic Trends from 2011 to 2021

Abstract The Oklahoma Quality Beef Network (OQBN) is a partnership between the Oklahoma State University Extension Service and the Oklahoma Cattlemen’s Association, with the goal of providing and promoting value-added marketing opportunities for beef cattle producers. The Oklahoma Beef Network’s goal is realized through the implementation of the OQBN Vac-45 Program. The OQBN Vac-45 Program is a beef calf preconditioning program, requiring specific vaccination and management practices. Calves that fulfill program requirements receive OQBN Vac-45 Certification and may participate in an “OQBN Sanctioned Sale”. These sales occur as part of regularly scheduled livestock auction sales on specified dates at planned locations. Sale data for all calves sold at OQBN Sanctioned Sales (certified and non-certified calves) were collected each year to capture market premiums attained by OQBN Vac-45 certified calves. The objective of this study was to analyze 11 years of beef calf sale data (2011-2021), collected by extension specialists at 91 individual OQBN Vac-45 sales, which took place at 10 Oklahoma livestock auction locations. An average of 8 sales were conducted each year. A total of 149,525 calves were described using 42 market characteristics for 12 market traits (the number of assigned characteristics depended on the given trait). Market characteristics were analyzed as percentages based on the total number of calves recorded each year. Linear and quadratic regression analysis procedures, with year as the fixed effect were performed using R Statistical Software (v4.1.3; R Core Team 2022). A linear increase in the percentage of red-hided calves sold over time was observed, explained by (R2 = 0.51, P = 0.008). A Kansas State University study by McCabe et al. (2020) regarding breed trends in beef calf lots sold in video auctions from 1995 to 2018, indicated an increase in the number of calves sired by Red Angus bulls (P < 0.0001). An inverse quadratic effect was observed with the percentage of over-conditioned “fleshy” calves decreasing (R2 = 0.89, P < 0.05) and the number of optimally conditioned “average flesh” calves increasing (R2 =0.95. P < 0.05) over time, indicating optimal calf nutritional management. Quadratic regression indicated a decreasing trend (R2 = 0.60, P = 0.01) in the percentage of calves participating in certified preconditioning programs over time, indicating that producers may perceive certified preconditioning programs as an unneeded additional cost. However, from 2011 to 2021 calves enrolled in the OQBN Vac-45 Program received an average premium of $12.55/cwt compared with non-preconditioned calves sold in the same sales. Further data are needed to evaluate the frequency and efficacy of preconditioning practices occurring without participation in certified programs.

Economics of Smaller Aberdeen-Derived Beef Cows

AbstractWe investigate differences in profitability of three Aberdeen-influenced breeds, Angus, Red Angus, and American Aberdeen. Using data from North Dakota, we measure differences in birth weights, calving intervals, weaning weights, cow weights, and profitability. Weaning weights differ between breeds, setting up a trade-off between lower feed costs for smaller cows and higher revenue for larger cows. American Aberdeen-influenced cows bred to Red Angus bulls have $1–$6 per acre higher returns than Angus or Red Angus-influenced cows. Aberdeen sires have the lowest returning calves.

281 The Effects of Whole Cottonseed Supplementation on Performance, Breeding Soundness Exams, and Manganese Superoxide Dismutase Concentrations in the Blood and Semen of Beef Bulls

Abstract The objective of this research was to determine the effects of whole cottonseed containing gossypol on post-pubertal beef bulls. In a two-year study, 46 Angus and Red Angus bulls (body weight 457.0 ± 85.2 kg; 16 to 20-months of age) were stratified by BW and randomly assigned to 1 of 3 levels of whole cottonseed supplementation while receiving ad libitum roughage. The treatments included: DD (n = 14, control; 3.18 kg/d of dried distillers grain, W/D (n = 16; 1.59 kg/d of whole cottonseed and 1.59 kg/d of dried distillers grain), or WW (n = 16 3.18 kg/d of whole cottonseed). Diets were formulated to be isocaloric and isonitrogenous. In both years, bulls were weighed, administered a breeding soundness exam, and morphological characteristics of spermatozoa were measured on d 0, 28, and 60. In year 1, blood and semen samples were collected on d 0, 28, and 60 to measure manganese superoxide dismutase activity. There was no treatment effect for blood or semen manganese superoxide dismutase concentration (P > 0.255). There was a treatment effect (P < 0.02) for average daily gain as bulls fed WW gained less compared to those fed WD and DD (0.96, 1.23, and 1.39 kg/d, respectively). No treatment effect was observed for scrotal circumference (P > 0.50). There were no treatment × time interactions, treatment, or time main effects for percentages of normal spermatozoa, spermatozoa with coiled or folded tails, or proximal droplets (P > 0.12). There was a treatment effect on the amount of swollen midpiece or abnormal head as bull in the DD treatment had a greater (P < 0.02) percentage of other abnormalities compared to WW, but WD was not different (P > 0.16). Inclusion of whole cottonseed may affect average daily gain, but does not affect reproductive parameters of beef bulls.

Relationships Among Maternal Traits and Sale Prices of Red Angus Bulls Sold at Auction From 2017 Through 2019

Relationships Among Maternal Traits and Sale Prices of Red Angus Bulls Sold at Auction From 2017 Through 2019

Relationships Among Terminal Traits and Sale Prices of Red Angus Bulls Sold at Auction From 2017 Through 2019

Relationships Among Terminal Traits and Sale Prices of Red Angus Bulls Sold at Auction From 2017 Through 2019

PSI-36 Phenotypic Relationship of Feed Efficiency and Fertility in Angus and Red Angus Bulls

Abstract Recent advances in measuring feed intake improve selection for efficient beef bulls; however, such selection must not decrease bull fertility. Objectives herein were to determine the phenotypic relationship between feed efficiency and fertility traits in growing Angus (n = 14) and Red Angus (n = 14) bulls. Two feeding trials were conducted at the CSU, Chico University Farm in 2017 (87 d) and 2018 (84 d). Each year, bulls were randomly assigned to 7 x 18 m pens equipped with GrowSafe feed intake units and allowed ad libitum access to water and feed (CP: 15.6%, TDN: 56.22%, NDF: 52%, DM basis). Performance traits included: feed conversion ratio (FCR) and residual feed intake [RFI; measured as the difference between predicted dry matter intake (PDMI) and actual dry matter intake (DMI)], start weight (SWT), end weight (EWT), metabolic mid-weight (MMWT), residual gain and average daily gain (ADG). Breeding soundness exams (BSE) were conducted at 18 mo of age and included traits: scrotal circumference (SC), motility (MT), and morphology (MP). Residual feed intake was calculated by regressing DMI on ADG and MMWT. The RFI group was categorized as low (0.5 SD above the RFI mean), marginal (± 0.5 SD about the RFI mean), and high (0.5 SD above the RFI mean) by year. Data were analyzed using ANOVA, blocking on year-pen and fitting breed and RFI group as independent factors. Tukey pairwise contrasts were run. Motility among breeds and RFI group were analyzed using chi-square. Pearson correlations were calculated between growth, feed efficiency, and BSE measures of SC and MP. There were no differences (P > 0.05) among breeds nor RFI groups for SWT, EWT, MMWT, residual gain, SC, and MT. No interaction was detected between breed and RFI group with exception of MP (P = 0.049); specifically, low RFI Red Angus bulls had poor MP compared to marginal and high RFI groups (66.94 ± 6.87 vs. 87.43 ± 3.77 and 93.74 ± 5.48 %, respectively). Angus bulls were superior to Red Angus bulls in ADG (1.23 ± 0.04 vs. 1.06 ± 0.05 kg/d; P = 0.01), FCR (7.98 ± 0.31 vs. 9.18 ± 0.38; P = 0.04), and RFI (-0.24 ± 0.09 vs. 0.09 ± 0.11 kg DMI/d; P = 0.04). High and marginal RFI groups had greater DMI compared to low RFI group (10.40 ± 0.26 and 9.64 ± 0.18 kg/d vs. 8.31 ± 0.32 kg/d; P < 0.001). There were no significant phenotypic correlations between growth and efficiency measures with SC and MP (P > 0.05). Cumulatively, results indicate that SC and MT were not affected in efficient bulls.

Growth Performance and Meat Quality of Purebred Bulls Reared under Intensive Production Systems

Background: Growth ability and meat performance are of great economic importance in beef cattle. Therefore, breed comparison experiments are needed to provide valuable information on the suitability of different beef breeds for different production conditions. The aim of the present study was to compare the growth performance and meat quality of young Red Angus, Salers and Limousin bulls. Methods: The material comprised 30 bulls of Red Angus (RA), Salers (SL) and Limousin (LM) breeds. The parameters studied were 210-d bodyweight and daily gains from birth to weaning and to finishing, as well as from weaning to finishing. The finished bulls were slaughtered after 12-hour fasting and post-slaughter evaluation was carried out. The compositions of the samples of meat from the longest dorsal muscle (m. longissimus dorsi) were subjected to basic chemical analysis and sensory analysis. Result: The best results in the period of maternal nursing were obtained by the SL bulls and during intensive fattening, by the LM bulls. The differences existed in the chemical composition and sensory characteristics of meat from the bulls of the studied breeds. The RA breed demonstrated the highest content of intramuscular fat in the longissimus dorsi muscle and received higher scores for sensory characteristics.

Taxonomic and functional assessment using metatranscriptomics reveals the effect of Angus cattle on rumen microbial signatures

A greater understanding of the rumen microbiota and its function may help find new strategies to improve feed efficiency in cattle. This study aimed to investigate whether the cattle breed affects specific ruminal taxonomic microbial groups and functions associated with feed conversion ratio (FCR), using two genetically related Angus breeds as a model. Total RNA was extracted from 24 rumen content samples collected from purebred Black and Red Angus bulls fed the same forage diet and then subjected to metatranscriptomic analysis. Multivariate discriminant analysis (sparse partial least square discriminant analysis (sPLS-DA)) and analysis of composition of microbiomes were conducted to identify microbial signatures characterizing Black and Red Angus cattle. Our analyses revealed relationships among bacterial signatures, host breeds and FCR. Although Black and Red Angus are genetically similar, sPLS-DA detected 25 bacterial species and 10 functions that differentiated the rumen microbial signatures between those two breeds. In Black Angus, we identified bacterial taxa Chitinophaga pinensis, Clostridium stercorarium and microbial functions with large and small subunits ribosomal proteins L16 and S7 exhibiting a higher abundance in the rumen microbiome. In Red Angus, nonetheless, we identified the poorly characterized bacterial taxon Oscillibacter valericigenes with a higher abundance and pathways related to carbohydrate metabolism. Analysis of composition of microbiomes revealed that C. pinensis and C. stercorarium exhibited a higher abundance in Black Angus compared to Red Angus associated with FCR, suggesting that these bacterial species may play a key role in the feed conversion efficiency of forage-fed bulls. This study highlights how the discovery of signatures of bacterial taxa and their functions can be used to harness the full potential of the rumen microbiome in Angus cattle.

Effect of bovine genotype on innate immune response of heifers to repeated lipopolysaccharide (LPS) administration

This pilot study provides a preliminary assessment of the impact of genotype on acute innate immune pro-inflammatory, metabolic and endocrine responses to repeated lipopolysaccharide (LPS) administered to growing heifers. Heifers (n = 4/genotype) were from unselected (stable milk yield since 1964, UH) or contemporary (CH) Holstein cows that differed in milk yield (6200 vs 11,100 kg milk/305 d) or from contemporary Black Angus (CA) cows bred to contemporary Red Angus bulls. Heifers were challenged with iv administration of 0.5 μg LPS/kg body weight on day 1 (Challenge 1) and d 5 (Challenge 2) of study to assess endotoxin tolerance. Plasma was collected at -1, -0.5, 0, 1, 2, 3, 4, 6, 8, and 24 h relative to each LPS administration. Rectal body temperature (BT) was measured before each blood sampling and at 5 and 7 h. Data were analyzed by repeated measures with sampling time as the repeated effect. Each genotype had at least one pro-inflammatory response that indicated it might have a more robust response than the other genotypes. The CH heifers had a greater TNF-α response, UH heifers had greater IL-6 and XO responses and CA heifers had greater BT and SAA response to LPS than the other genotypes. There was a genotype by time by interaction as cortisol peaked earlier in CH and UH than in CA heifers. Glucose response was less in CA and insulin response was greater in CH heifers. Endotoxin tolerance to LPS was evident as pro-inflammatory, cortisol, glucose and insulin responses were less during Challenge 2 than during Challenge 1. Differences among genotypes during Challenge 1 were eliminated during Challenge 2 except for the greater SAA response in CA heifers and indicate the potential for differential impacts of genotype on the development of endotoxin tolerance. Specific reasons for these effects of genotype are not clear from these data but the results support the hypothesis for differential innate immune signaling among these bovine genotypes.

Comparison of meat quality characteristics, growth, and feed efficiency of intact and castrated post-pubertal bovine males

Yearling Red Angus or Black Angus bulls (n = 24; initial BW = 1,336 ± 25.1 lb; (606 ± 11.4 kg); average 16 mo of age) were used to evaluate the effects of castration and use of growth promoting technology (STR) on performance, carcass traits, and meat quality characteristics when compared to intact (BULL) post-pubertal male cattle. The STR treatment included administration of a combination 120 mg trenbolone acetate + 24 mg estradiol growth-promoting implant on d 0 and feeding ractopamine hydrochloride the last 28 d on feed. Cattle were individually fed a corn-based finishing diet for 62 d and harvested at a commercial abattoir. Intact bulls had greater average daily gain (4.08 vs 3.19 lb or 1.85 vs 1.45 kg/d; P = 0.02) and feed:gain ratio (8.54 vs 10.97; P = 0.02) than STR. There were no treatment differences for dry-matter intake, quality or yield grade, hot carcass weight, back-fat thickness, or dressing percent (P < 0.05). Longissimus muscle area was greater in BULL compared to STR carcasses (16.6 vs 15.0 in2 or 106.9 vs 96.8 cm2; P < 0.01). Warner-Bratzler Shear Force was not affected (P > 0.05) by treatment. Intact bulls had improved performance with no differences in carcass characteristics, tenderness, or sensory panel measurements compared to STR treatment.

Enrichment of Bovine Semen with X-Bearing Spermatozoa Using Percoll? and Optiprep? Discontinuous Gradients

In cattle, sex selection has a significant economic impact when it improves herd capacity of milk or meat production. Density gradient centrifugation might be an approach to sexing spermatozoa because of the additional DNA content and volume of X-bearing sperm head. In the present work, the accuracy of sperm sexing by Percoll™ and OptiPrep® gradients centrifugation was compared. Bovine semen from three breeds (Holstein, Gir, and Red Angus) was used. The sperm viability and sexing accuracy after sperm selection by centrifugation of low and high-density discontinuous gradient composed by three layers of Percoll™ or OptiPrep® were assessed by in vitro embryo production (IVP) and pregnancy rate following artificial insemination (AI). After IVP, cleavage rate was higher (P < 0.05) for unsexed (81.3%) than for sexed (75.5%) spermatozoa. A significantly lower cleavage rate was observed for sexed (76.1%) spermatozoa when compared to sexed Red Angus (81.2%) spermatozoa. Additionally, significantly lower blastocyst rate was observed using Holstein sexed sperm by OptiPrep® gradient (23.3%) when compared with Gir (41.9%) and Red Angus (48.7%) sexed sperm by Percoll™ gradient. Nevertheless, in all breeds analyzed, a significant sex ratio deviation to females was observed. Analyzing the pregnancy rate after AI with sexed sperm by Percoll™ and OptiPrep®, semen from Gir bulls presented lower (P <0.05) pregnancy/AI (61.3%)when compared to Red Angus (75.9%) and Holstein (77.4%) and bulls. From the results, it was concluded that the increase in female percentage after insemination and/or IVP with bovine sexed sperm by centrifugation of high density gradient composed by three layers of Percoll™ and OptiPrep® may allow this spermatozoa sexing technique to be used in large scale which would support genetic enhancement for milk and meat production as well as for progeny tests in cattle.

Elemental Composition of Muscle Tissue of Various Beef Breeds Reared Under Intensive Production Systems

Concentrations of major nutritional and trace elements (Ca, P, Mg, Na, K, Fe, Zn, Cu, Mn, Se, Co, Cr, Ni, Sr, Ba) and toxic heavy metals (Cd, Pb) were analyzed in the meat of Limousin, Red Angus and Salers bulls. Elements were determined using inductively coupled plasma emission atomic spectrometry. The conducted research showed that the meat of compared breeds differed in the concentrations of Cu, Zn, Fe, Se and K. The meat from Limousin bulls had significantly lower Zn (P<0.001) and Cu (P<0.05) contents than that of Red Angus and Salers bulls. Moreover, the meat of Red Angus bulls was characterized by a significantly (P<0.001) lower K content and significantly (P<0.05) higher Fe content compared to those in the Limousin and Salers bulls as well as significantly (P<0.05) higher Se content in comparison with the Salers bulls. No breed differences in the concentrations of Pb and Cd were found; however, the Pb concentration in meat was higher than the recommended standards. In the meat of all three breeds, the significant strong positive correlations were observed between the contents of Pb-Cd, Pb-Ni, Cd-Ni and K-P. The correlations between other elements within each of the breeds separately were also found.

Association of polymorphisms in the leptin and thyroglobulin genes with meat quality and carcass traits in beef cattle

The objective of the present study was to estimate the allelic and genotypic frequencies of the polymorphisms E2FB (AY138588.1: c.305C> T), located in the leptin gene (LEP), and TG5 (X05380.1:g.-422C>T), located in the thyroglobulin gene (TG), and evaluate the association of these polymorphisms in crossbred cattle of seven distinct genetic groups with the following traits: slaughter weight (SW), hot carcass weight (HCW), hot carcass yield (HCY), carcass fat thickness (CFT), ribeye area (REA), marbling (MARM) and shear force (SF). The animals were genotyped using the PCR-RFLP (Polymorphism Chain Reaction-Restriction Fragment Length Polymorphism) technique, using 201 products obtained from F1 Caracu × Nellore, Angus × Nellore and Valdostana × Nellore cows, mated to Canchim, Caracu and Red Angus bulls (only Caracu × Nellore cows were used with Red Angus bulls). The allelic and genotypic frequencies were compared using the Chi-squared test. Associations between the genotype of each polymorphism and the traits were analyzed using the General Linear Model (GLM) of statistical software SAS. The least squares means of genotypes of the polymorphisms were compared using Student's t test. The E2FB polymorphism in the LEP gene was associated with CFT, showing the potential for use in national programs for genetic improvement of beef cattle, through the inclusion of SNP in genotyping commercial tests. The TG5 polymorphism in the TG gene was not associated with any of the evaluated traits and was considered ineffective for selection of beef cattle in Brazilian herds.

A methodological approach to estimate the lactation curve and net energy and protein requirements of beef cows using nonlinear mixed-effects modeling1

The objective of this study was to evaluate methods to predict the secretion of milk and net energy and protein requirements of beef cows (Bos indicus and B. taurus) after approximately 1 mo postpartum using nonlinear mixed-effect modeling (NLME). Twenty Caracu × Nellore (CN) and 10 Nellore (NL) cows were inseminated to Red Angus bulls, and 10 Angus × Nellore (AN) were bred to Canchim bulls. Cows were evaluated from just after calving (25 ± 11 d) to weaning (220 d). Milk yield was estimated by weighing calves before and after suckling (WSW) and by machine milking (MM) methods at 25, 52, 80, 109, 136, 164, 193, and 220 ± 11 d of lactation. Brody and simple linear equations were consecutively fitted to the data and compared using information criteria. For the Brody equation, a NLME model was used to estimate all lactation profiles incorporating different sources of variation (calf sex and breed of cow, cow as a nested random effect, and within-cow auto-correlation). The CV for the MM method (29%) was less than WSW (45%). Consequently, the WSW method was responsible for reducing the variance about 1.5 times among individuals, which minimized the ability to detect differences among cows. As a result, only milk yield MM data were used in the NLME models. The Brody equation provided the best fit to this dataset, and inclusion of a continuous autoregressive process improved fit (P < 0.01). Milk, energy and protein yield at the beginning of lactation were affected by cow genotype and calf sex (P < 0.001). The exponential decay of the lactation curves was affected only by genotype (P < 0.001). Angus × Nellore cows produced 15 and 48% more milk than CN and NL during the trial, respectively (P < 0.05). Caracu × Nellore cows produced 29% more milk than NL (P < 0.05). The net energy and net protein requirements for milk yield followed a similar ranking. Male calves stimulated their dams to produce 11.7, 11.4, and 11.9% more milk, energy and protein, respectively (P < 0.05). The MM method is better than the WSW technique to detect genetic or environmental differences in milk yield among beef cows. The data obtained by the MM method and analyzed by NLME models allows the inclusion of fixed effects, random effects and an auto-regressive process in lactation equations to describe lactation curves and net energy and protein requirements. The NLME is a powerful tool to describe differences in the secretion of milk due to heterosis and cell mammary external stimulus in beef cows.

Partial-genome evaluation of postweaning feed intake and efficiency of crossbred beef cattle1,2

The effects of individual SNP and the variation explained by sets of SNP associated with DMI, metabolic midtest BW, BW gain, and feed efficiency, expressed as phenotypic and genetic residual feed intake, were estimated from BW and the individual feed intake of 1,159 steers on dry lot offered a 3.0 Mcal/kg ration for at least 119 d before slaughter. Parents of these F(1) × F(1) (F(1)(2)) steers were AI-sired F(1) progeny of Angus, Charolais, Gelbvieh, Hereford, Limousin, Red Angus, and Simmental bulls mated to US Meat Animal Research Center Angus, Hereford, and MARC III composite females. Steers were genotyped with the BovineSNP50 BeadChip assay (Illumina Inc., San Diego, CA). Effects of 44,163 SNP having minor allele frequencies >0.05 in the F(1)(2) generation were estimated with a mixed model that included genotype, breed composition, heterosis, age of dam, and slaughter date contemporary groups as fixed effects, and a random additive genetic effect with recorded pedigree relationships among animals. Variance in this population attributable to sets of SNP was estimated with models that partitioned the additive genetic effect into a polygenic component attributable to pedigree relationships and a genotypic component attributable to genotypic relationships. The sets of SNP evaluated were the full set of 44,163 SNP and subsets containing 6 to 40,000 SNP selected according to association with phenotype. Ninety SNP were strongly associated (P < 0.0001) with at least 1 efficiency or component trait; these 90 accounted for 28 to 46% of the total additive genetic variance of each trait. Trait-specific sets containing 96 SNP having the strongest associations with each trait explained 50 to 87% of additive variance for that trait. Expected accuracy of steer breeding values predicted with pedigree and genotypic relationships exceeded the accuracy of their sires predicted without genotypic information, although gains in accuracy were not sufficient to encourage that performance testing be replaced by genotyping and genomic evaluations.

Estimativa das distâncias genéticas e componentes principais em bovinos de corte no Brasil

The objective of this study was to estimate principal components for, and correlations between, weights at birth (BWT), 205d (WT205), 365d (WT3650), 550d (WT550) and 730d (WT730) using multivariate analysis of data from 2,237 animals from IAPAR, PR. Calves were produced from Nellore, Guzera, Red Angus, Marchigiana, and Limousin bulls mated to Nellore, ½ Guzera x ½ Nellore, ½ Red Angus x ½ Nellore, ½ Marchigiana x ½ Nellore, ½ Simmental x ½ Nellore, ¾ Nellore x ¼ Red Angus, and ½ Red Angus x ¼ Guzera x ¼ Nellore cows. Correlations ranged from 0.22 (BWT with WT730) to 0.73 (WT365 with WT550). The proportions of variation justified by the principal components were: first, 56%; first and second, 72%; first through third, 87%; and first four, 95%. The MANOVA tests model a separate variance for each trait (in this case, a separate variance for each of the five traits, and a separate covariance for each of the pairs of traits). The Wilks Lambda indicates a significant difference in genetic distance between breeds of dam based on the performance of calves. Dams composed of ½ Marchigiana x ½ Nellore versus ½ Simmental x ½ Nellore had the least genetic distance (0.058), while Nellore versus ½ Simmental x ½ Nellore were most distant (2.738). Multivariate analysis can be used to estimate principal components for developing economic weights and accurate indices important in beef selection. Trees generated from cluster analysis of progeny weights can be used to visualize genetic grouping of breed of dam.

Net requirements of calcium, magnesium, sodium, phosphorus, and potassium for growth of Nellore × Red Angus bulls, steers, and heifers

A comparative slaughter trial was conducted to assess the net requirements for gain of Ca, P, Na, K and Mg of bulls, steers and heifers of Nellore and Red Angus crossbreds. Twenty seven F1 Nellore and Red Angus crossbred calves (9 steers, 9 bulls, and 9 heifers), averaging 274 kg BW, were used. At the beginning of the trial, three animals from each gender were slaughtered to determine the initial body composition. The remaining 18 animals (3 animals of each gender) were randomly assigned to two treatments: fed 0.75 or 1.5% of BW of concentrate. The diets were based on corn silage and were isonitrogenous (2% N, DM). After three growing periods of 28 d, all animals were slaughtered. The cleaned gastrointestinal tract, organs, carcass, head, hide, tail, feet, and tissues were weighed to determine the empty BW (EBW). These parts were ground separately and subsampled for chemical analyses. The log of the contents of each mineral in the empty body was regressed on the log of the EBW to estimate the net requirement for each mineral per kg of empty body gain (EBG). There were no differences ( P > 0.05) in the net requirements for growth of all macrominerals among genders. The equations of the pooled data of the net requirements for growth (g/kg EBG) were: 332.6 × EBW − 0.6367 for Ca, 112.1 × EBW − 0.5615 for P, 10.85 × EBW − 0.3992 for Na, 4.01 × EBW − 0.153 for K, and 3.589 × EBW − 0.462 for Mg. Our findings indicated that retained Ca and retained P were poorly related to the retained protein.

Models for Genetic Evaluation of Scrotal Circumference in Red Angus

Growth and scrotal records were obtained to estimate age of dam and age at measurement adjustment factors for yearling scrotal circumference in Red Angus bulls (n = 40,865), and to estimate genetic parameters. The linear partial regression coefficient for age at measurement was 0.0323 cm/d. The recommended factors were 0.70, 0.37, 0.08, and 0.30cm to adjust the scrotal circumference records of yearling Red Angus bulls out of 2-, 3-, 4-, and ≥ 10-yr old cows to a mature (5 to 9 yr) age of dam equivalent. Adjusted 365-d scrotal circumference (SC365) records were fitted to animal models including direct genetic and from 0 to 3 maternal effects; however, maternal effects were negligible. Her-itability for SC365 was 0.51 ± 0.02 from a model including only direct genetic effects. Bivariate models were used to estimate parameters for SC365 with birth (BWT) and 205-d BW, and 160-d postweaning gain (PWG). Estimated genetic correlations (± 0.03) were 0.10, 0.13, and 0.13 for SC365 with direct effects on BWT, 205-d BW, and PWG, respectively. Maternal BWT had a low genetic correlation (0.05 ± 0.05) with SC365, but the genetic correlation between maternal 205-d BW and SC365 was moderate (0.35 ± 0.04). In addition to the recommendations for adjustment of scrotal circumference, these results suggest that direct genetic effects on SC365 could be used in selection programs, and that increasing selection for SC365 would be concomitant with growth up to yearling age and not antagonistic to maternal ability in Red Angus.

Energy and protein requirements for growth and maintenance of F1 Nellore × Red Angus bulls, steers, and heifers1

A comparative slaughter trial was conducted with 36 F1 Nellore x Red Angus calves (12 steers, 12 bulls, and 12 heifers), averaging 274 kg of BW, to assess the net requirements of protein and energy for growth and maintenance. Three cattle from each group (i.e., steers, bulls, and heifers) were slaughtered at the beginning of the trial to determine the initial body composition. The remaining calves were randomly assigned to 1 of 3 treatments: maintenance (diet containing 70% of DM as corn silage fed at 1.2% of BW daily) or concentrate at 0.75 or 1.5% of BW daily with corn silage available for ad libitum consumption. The diets were isonitrogenous (2% N, DM basis). The experimental design provided ranges in ME intake, BW, and ADG for the development of regression equations to predict the maintenance requirements for NE and net protein (MRNE and MRNP, respectively) and the growth requirement for NE and net protein (GRNE and GRNP, respectively). After 84 d of growth, the cattle were slaughtered. The cleaned gastrointestinal tracts, organs, carcasses, heads, hides, tails, feet, blood, and tissues were weighed to measure empty BW (EBW). These parts were ground separately and subsampled for chemical analyses. For each animal within a period, DMI was measured daily and samples of feces were collected to determine diet digestibility. There were no differences in MRNE (P = 0.06) among groups. The combined data indicated a MRNE of 71.2 kcal x kg(-0.75) of EBW x d(-1), with a partial efficiency of use of ME to NE(m) of 0.71. The partial efficiency of use of ME to NE for growth was 0.54 for bulls, 0.47 for steers, and 0.54 for heifers. The GRNE for steers and heifers were similar (P = 0.15) but were 18.7% greater (P = 0.03) for steers and heifers than for bulls. The MRNP did not differ among groups and averaged 2.53 g of CP x kg(-0.75) of EBW x d(-1). Likewise, GRNP was not different among groups. The percentage of retained energy deposited as protein (RE(p)) increased as the content of retained energy in the gain (RE(c), Mcal/kg of empty body gain) decreased. The RE(p) equation of the pooled data was 46.5 x e(-0.2463 x RE(c)). We conclude that the energy requirement of crossbred Bos indicus x Bos taurus for maintenance might be less than that of purebred Bos taurus and that RE(p) is nonlinearly, negatively correlated with RE(c). The GRNE was less for bulls than for steers and heifers. However, we found no differences in MRNE, MRNP, and GRNP for bulls, steers, and heifers of Nellore x Red Angus crossbreds.