Nellore Cattle Research Articles

A veterinary cerumenomic assay for bovine laminitis identification.

Bovine laminitis disorder results in animal welfare and economic concerns in dairy and beef farms worldwide. However, the affected metabolic pathways, pathophysiologic characteristics, and inflammatory mechanisms remain unclear, hampering the development of new diagnostics. Using cerumen (earwax) as a source of volatile metabolites (cerumenomic) that carry valuable biological information has interesting implications for veterinary medicine. Nonetheless, up to now, no applications of veterinary cerumenomic assays have been made to identify bovine laminitis. This work aims to develop a veterinary cerumenomic assay for bovine laminitis identification that is non-invasive, robust, accurate, and sensitive to detecting the metabolic disturbances in bovine volatile metabolome. Twenty earwax samples (10 from healthy/control calves and 10 from laminitis calves) were collected from Nellore cattle, followed by Headspace/Gas Chromatography-Mass Spectrometry (HS/GC-MS) analysis and biomarker selection in two multivariate approaches: semiquantitative (intensity data) and semiqualitative (binary data). Following the analysis, cerumen volatile metabolites were indicated as candidate biomarkers for identifying bovine laminitis by monitoring their intensity or occurrence. In the semiquantitative strategy, the p-cresol presented the highest diagnostic figures of merit (area under the curve: 0.845, sensitivity: 0.700, and specificity: 0.900). Regarding the binary approach, a panel combining eight variables/volatiles, with formamide being the most prominent one, showed an area under the curve, sensitivity, and specificity of 0.97, 0.81, and 0.90, respectively. In summary, this work describes the first veterinary cerumenomic assay for bovine laminitis that indicates new metabolites altered during the inflammatory condition, paving the way for developing laminitis early diagnosis by monitoring the cerumen metabolites.

Genome-wide scans identify biological and metabolic pathways regulating carcass and meat quality traits in beef cattle

Genome association studies (GWAS) provides knowledge about the genetic architecture of beef-related traits that allow linking the target phenotype to genomic information aiding breeding decision. Thus, the present study aims to uncover the genetic mechanism involved in carcass (REA: rib eye area, BF: backfat thickness, and HCW: hot carcass weight) and meat quality traits (SF: shear-force, MARB: marbling score, and IMF: intramuscular fat content) in Nellore cattle. For this, 6910 young bulls with phenotypic information and 23,859 animals genotyped with 435 k markers were used to perform the weighted single-step GBLUP (WssGBLUP) approach, considering two iterations. The top 10 genomic regions explained 8.13, 11.81, and 9.58% of the additive genetic variance, harboring a total of 119, 143, and 95 positional candidate genes for REA, BF, and HCW, respectively. For meat quality traits, the top 10 windows explained a large proportion of the total genetic variance for SF (14.95%), MARB (17.56%), and IMF (21.41%) surrounding 92, 155, and 111 candidate genes, respectively. Relevant candidate genes (CAST, PLAG1, XKR4, PLAGL2, AQP3/AQP7, MYLK2, WWOX, CARTPT, and PLA2G16) are related to physiological aspects affecting growth, carcass, meat quality, feed intake, and reproductive traits by signaling pathways controlling muscle control, key signal metabolic molecules INS / IGF-1 pathway, lipid metabolism, and adipose tissue development. The GWAS results provided insights into the genetic control of the traits studied and the genes found are potential candidates to be used in the improvement of carcass and meat quality traits.

Prediction models of carcass characteristics from non‑castrated Nellore cattle finished in the feedlot system under tropical conditions.

Our objective was to use measures of intake and productive performance to adjust prediction models for the carcass traits of non-castrated Nellore cattle finished in a feedlot. Individual data from 168 non-castrated male Nellore steers finished in feedlot between the years 2016-2021 were used. Descriptive statistical analyzes and Pearson correlation coefficients were performed. The outliers were tested by evaluating the studentized residuals in relation to the values predicted by the equations. Residues that were outside the range of -2.5 to 2.5 were removed. The goodness of fit of the developed equations was evaluated by the coefficients of determination (R2) and root mean square error (RMSE). Models for carcass yield, subcutaneous fat thickness, ribeye area, and shear force were adjusted. Means of 53.5% carcass yield, 4.8mm subcutaneous fat thickness, 73 cm2 loin eye area, and 8.1kg shear force were observed. The observed average intakes were 9.9kg/day of dry matter, 3.3kg/day of neutral detergent fiber content, 1.5kg/day of crude protein, and 7.1kg/day of total digestible nutrients. The average confinement time was 113days, the average total weight gain was 152.2kg and the average daily gain was 1.35kg/day. Intake measures significantly correlated with shear force and subcutaneous fat thickness and ribeye area. Carcass yield was significantly correlated with total weight gain, feedlot time, and hot carcass weight. Measures of nutrient intake, performance, and confinement time can be used as predictors of carcass yield, ribeye area, fat thickness, and shear force of non-castrated Nellore cattle finished in a feedlot. The prediction equations for ribeye area, carcass yield, subcutaneous fat thickness, and shear force showed sufficient precision and accuracy for non-castrated Nellore cattle finished in confinement systems under tropical conditions. All equations can be used with caution to estimate carcass traits of cattle finished in a feedlot using measures of intake and productive performance.

Effects of mineral and vitamin supplementation on pregnancy rates in Nelore cattle submitted to FTAI programs with different reactivity scores

A high-reactivity herd temperament reduces productivity and profitability in cattle farming. In Bos taurus indicus (Nellore) cattle, we hypothesized that a higher reactivity score is associated with a lower pregnancy rate, and that injectable supplementation with minerals (Cu, Zn, Mn, Se) and vitamins (A, E) would increase the pregnancy rate and reduce embryonic mortality in very reactive cows. Injectable supplement or control treatments were administered on days 25 and 10 before fixed-time artificial insemination (FTAI; Day 0 : day of FTAI). We selected 1722 cows 45 ± 7 days postpartum, with different behavioral reactivity levels, and a series of measures related to reproduction were measured. The cows were randomly grouped and received sc 1 mL/50 kg live weight of the supplement (n = 872) or placebo (n = 850), 25 and 10 days before the FTAI protocol (Day–25 and Day–10 respectively). On Day −10, devices containing 1 g progesterone were inserted into the vagina, and 2 mg estradiol benzoate was applied intramuscularly. On Day–2, the devices were removed and 530 µg of sodium d-cloprostenol, 300 IU of equine chorionic gonadotropin, and 1 mg of estradiol cypionate were applied. At 48 h after final injection, the cows were subjected to FTAI (Day 0). On Day - 25 (25 days before IATF), temperament was graded as 3 to 12 using composite reactivity score (RS), which evaluates movement and breathing while the animal is in the cattle chute, and their escape velocity, and was used to classify cows as calm (RS ≤ 4; n = 590), reactive (RS 5 to 8; n = 573), and very reactive (RS ≥ 9; n = 559). On Day 0, calm cows had a higher largest follicle diameter on the FTAI compared to reactive and very reactive (14.4 + 0.2 vs. 13.6 + 0.4 and 13.2 + 0.2 mm, respectively; P = 0.03). Interactions were observed, where supplemented cows compared to those no supplemented had higher pregnancy on Day 30 (P = 0.04; 60.00 vs. 54.10 % calm and 58.00 vs. 52.50 % very reactive) and Day 60 (P = 0.03; 58.70 vs. 47.90 % calm, 52.20 vs. 49.10 % reactive and 48.40 vs. 41.30 % very reactive) and reduced embryonic loss at 30 to 60 d (P = 0.04; 2.00 vs. 6.10 % calm, 4.20 vs. 8.40 % reactive and 9.60 vs. 11.20 % very reactive). Supplementation on Days–25 and–10 improved pregnancy rates and reduced embryonic in calm and very reactive cows.

Unravelling the genetic variability of host resilience to endo- and ectoparasites in Nellore commercial herds

BackgroundHost resilience (HR) to parasites can affect the performance of animals. Therefore, the aim of this study was to present a detailed investigation of the genetic mechanisms of HR to ticks (TICK), gastrointestinal nematodes (GIN), and Eimeria spp. (EIM) in Nellore cattle that were raised under natural infestation and a prophylactic parasite control strategy. In our study, HR was defined as the slope coefficient of body weight (BW) when TICK, GIN, and EIM burdens were used as environmental gradients in random regression models. In total, 1712 animals were evaluated at five measurement events (ME) at an average age of 331, 385, 443, 498, and 555 days, which generated 7307 body weight (BW) records. Of the 1712 animals, 1075 genotyped animals were used in genome-wide association studies to identify genomic regions associated with HR.ResultsPosterior means of the heritability estimates for BW ranged from 0.09 to 0.54 across parasites and ME. The single nucleotide polymorphism (SNP)-derived heritability for BW at each ME ranged from a low (0.09 at ME.331) to a moderate value (0.23 at ME.555). Those estimates show that genetic progress can be achieved for BW through selection. Both genetic and genomic associations between BW and HR to TICK, GIN, and EIM confirmed that parasite infestation impacted the performance of animals. Selection for BW under an environment with a controlled parasite burden is an alternative to improve both, BW and HR. There was no impact of age of measurement on the estimates of genetic variance for HR. Five quantitative trait loci (QTL) were associated with HR to EIM but none with HR to TICK and to GIN. These QTL contain genes that were previously shown to be associated with the production of antibody modulators and chemokines that are released in the intestinal epithelium.ConclusionsSelection for BW under natural infestation and controlled parasite burden, via prophylactic parasite control, contributes to the identification of animals that are resilient to nematodes and Eimeria ssp. Although we verified that sufficient genetic variation existed for HR, we did not find any genes associated with mechanisms that could justify the expression of HR to TICK and GIN.

PSVII-5 Detection and Characterization of Copy Number Variation Regions in Three Selection Lines of Nellore Cattle

Abstract Copy number variations (CNV) can partially explain phenotypic variability in complex traits. Therefore, we aimed to identify and characterize CNV regions (CNVR) in Nellore cattle from three selection lines. These selection lines were established in 1981 and consist of a line selected based on heavier postweaning weight (NeS, n = 245), a line selected based on heavier postweaning weight and reduced residual feeding Intake (NeT, n = 556), and a line selected based on average postweaning weight (NeC, n = 114). Genotypes (GGP Indicus HD and GGP Indicus 50K panel) of 928 animals were analyzed. The CNV identification was performed per SNP panel using the PennCNV software. After identifying the CNVs, quality control was performed and the following exclusion criteria were used: Log R ratio > 0.30, B allele frequency "drift” < 0.01, and guanine-cytosine wave factor < 0.05. CNVR were determined by grouping individual CNVs with at least one overlapping base pair. The exclusive regions present in at least 10% of the animals from each population were identified. The GALLO R package was used for the annotation of genes in these regions, and the WebGestaltR package was used for the Gene Ontology analyses. Eight-hundred-and-twenty-three CNVRs (143 losses, 650 gains, and 30 mixed), 1,493 CNVRs (327 losses, 1,113 gains, and 53 mixed), and 482 CNVRs (90 losses, 378 gains, and 14 mixed) were identified in the NeS, NeT, and NeC lines, respectively. The CNVRs covered 1.61%, 2.54%, and 0.94% of the cattle genome in NeS, NeT, and NeC, respectively. Only 32 CNVRs were identified in at least 10% of the animals in NeS, 33 in NeT, and 25 in NeC. Of these regions, 2 are NeS exclusive, 4 are NeT exclusive, and 6 are NeC exclusive. Eight candidate genes in NeS, 20 candidate genes in NeT, and 16 genes in NeC overlapped with the exclusive regions. We identified some important genes such as SLC15A1 in NeS herd that have functions associated to nutrient absorption, MAPK1 identified in the NeT population is involved in a wide variety of cellular processes such as proliferation, differentiation, transcription regulation and development, and IQCA1L in the NeC population is involved in ATP activity. The genes identified are involved in 5 biological processes, such as response to growth factor, in NeT, and in 1 biological process (response to endoplasmic reticulum stress) in NeC. The differences observed in CNVR improve our understanding of the genetic architecture of the three Nellore selection schemes, given that the identification of genes in the CNVR allows the identification of genomic regions and biological processes that could be associated with the phenotypic differences between selection lines.

PSVII-4 Genetic Parameters for Various Semen Quality and Reproductive Performance Traits in Nellore Cattle Including X Chromosome Markers

Abstract Estimating genetic parameters of male and female fertility and reproduction traits is essential for optimizing beef cattle breeding programs. In general, only markers located on autosomal chromosomes are used for genetic evaluations. Sex chromosomes tend to be excluded due to the compensation mechanism of dosage of genes linked to the X chromosome, which is the second largest chromosome in the cattle genome and harbors many genes potentially influencing these traits. Therefore, we estimated genomic-based variance components, including the X chromosome in the variance components analysis for female precocity, fertility, and andrological traits based on the single-step GBLUP procedure and Bayesian inference. The dataset consisted of ~120,000 records for the probability of pregnancy at 14 months (PP14), early rebreeding (REBA), and stability (STAY). From the breeding soundness exam (BSE) of bulls, 20,000 records were obtained for semen quality, andrological biometry, semen defects, and bull fitness (BULL_FIT). The pedigree contained 660,608 animals, where 11,012 animals were genotyped for 770,111 SNPs. All traits have reasonable additive genetic variation and are heritable, with a substantial contribution from the X chromosome, indicating that genetic progress for these traits is feasible. The heritability estimates (h2) explained by autosomal and X chromosome SNPs was low and low-to-moderate, respectively, for female reproductive performance traits, such as REBA [0.17 (auto); 0.07 (sex chr)], PP14 (0.42;0.05), and STAY (0.32;0.01). For male traits, the heritability estimates based on the autosomes and X chromosome, respectively, ranged from 0.02 to 0.04 and from 0.01 to 0.03 for semen quality traits; from 0.10 to 0.68 and from 0.02 to 0.07 for morphological traits; from 0.10 to 0.12 and from 0.01 to 0.02 for semen defects traits; for bull evaluation (BULL_FIT) were observed h2 for autosomes 0.18 and 0.10 for sexual chromosome X. The results observed in this study indicate a substantial contribution of the X chromosome on fertility and reproductive performance traits. These findings will serve as background information for designing breeding programs for genetically improving semen production and quality and reproductive performance in Nellore cattle.

PSII-14 Chemical Composition of Tropical Forage Fertilized with Different Sources of Nitrogen Fertilizers

Abstract Nitrogen fertilization can improve the chemical composition of tropical forages, as nitrogen is required at all stages of plant development. The aim of this study was to verify the chemical composition of Urochloa brizantha cv. marandu fertilized with different sources of nitrogen fertilizers from the following treatments: without nitrogen fertilization (CO), fertilization with urea (UR), fertilization with ammonium nitrate (NI) and fertilization with ammonium sulfate (SA). The study was carried out from December 2021 to April 2022, in the cerrado biome of Brazil at the FCAV/UNESP Forage Sector, Jaboticabal Campus, during the rearing phase of Nelore cattle, non-castrated males kept on pasture, managed in a continuous stocking system and variable load capacity. In treatments with fertilization, 150 kg of N· ha-1 were applied, divided into 3 applications. The design used was in randomized blocks (DBC). The evaluation of the chemical composition of the forage was carried out from collections every 28 days of samples of the fraction of the forage consumed by the animals through the hand-plucking method. The samples were dried at 55ºC for 72 hours and ground in a Willey mill, with a 1 mm mesh sieve. The chemical composition of the forage was estimated by spectroscopy in the near infrared light region, NIRS (Near Infrared Spectrometer), using a modular FT-NIR spectrometer. The data obtained were submitted to ANOVA and Tukey's test (P ≤ 0.05), using the statistical program R, version 3.4.4. Nitrogen fertilization significantly increased the organic matter content of the forage (P = 0.001). The organic matter content of the non-fertilized treatment was 91.97%, while the average of the fertilized treatments was 92.22%. The percentage of crude protein in the forage also showed a significant difference (P < 0.001) between the non-fertilized treatment, which had an average of 10.64%, and the fertilized treatments, which had an average of 17.75%. The neutral detergent fiber and acid detergent fiber components also differed from the application of nitrogen fertilizer (P < 0.001) but did not differ between the types of fertilizers. The neutral detergent fiber content was significantly different (P < 0.001) between the non-fertilized treatment (59.21%) and the fertilized treatments (54.30%). The observed data for acid detergent fiber were 31.46% for the treatment without the use of fertilizers and 30.24% for the treatments with the use of fertilizers. Non-fibrous carbohydrates and liguinin components were also analyzed, but showed no difference between treatments, P = 0.078 and P = 0.209, respectively. This study confirms that the chemical composition of Urochloa brizantha cv. Marandu can be significantly improved through the application of nitrogen fertilizers. However, our results showed no significant difference between the types of fertilizers tested.

Behavioral and Morphological Traits of Nellore Cattle That Can Influence Calf Survival and Performance from Birth to Weaning

This study aimed to identify behavioral and morphological traits of Nellore cattle that can influence calves’ survival and pre-weaning performance. It was performed in two units of a large-scale cow–calf operation farm located in the Central-West region of Brazil, with 975 cow–calf dyads, by scoring cows’ maternal protective behavior, body condition, horns, udder suspension (US), teat size (TS) and calves’ vigor. TS was used to determine teat symmetry (TSm). The production unit where calves were born, their birth date, sex, and birth (BW) and weaning weights were also recorded. Cow ages at calving and production units were used to categorize the cows into twelve classes (Cage). The Shapiro–Wilk test alongside tables of frequencies were used to determine if continuous and categorical variables followed a normal distribution, respectively. Two datasets were considered in statistical analyses: (i) 975 dyad records were used to identify potential factors influencing calf survivability and (ii) 936 records of weaned calves were used to assess pre-weaning performance. Generalized linear models were used to assess the effect of target traits on the calves’ weight adjusted for 210 days of age (W210, kg) and pre-weaning average daily gain (preADG, kg/day). Tukey’s test was used to compare W210 and preADG means. Pearson’s correlation coefficients were estimated between BW, W210 and preADG. Cage, US and the TSm significantly affected pre-weaning calf performance (p < 0.01). Older cows (independently of the production unit) and those with intermediate US and symmetrical teats weaned heavier calves. As expected, positive and significant correlation was observed between BW and preADG (r = 0.35), which, in turn, was highly correlated with W210 (r = 0.99). We concluded that none of the behavioral and morphological traits influenced calf survivability, but cow age, US and TSm impacted pre-weaning performance, with 8- to 11-year-old cows and those with intermediate US and symmetric teats leading to better calf performance at weaning.

Economic considerations of breeding for polledness versus disbudding in beef cattle.

The domestication of animals has rendered horns less necessary for survival. Moreover, the use of polled and disbudded animals is interesting in order to avoid injuries of animals and handlers, among other advantages. We therefore conducted a comparative economic analysis of different traditional disbudding techniques versus selective breeding for polledness in Nelore cattle, the main beef breed of tropical systems in Brazil. The cost to obtain animals without horns was estimated in three different scenarios: disbudding with hot iron, disbudding with caustic paste, and phenotypic selection for polled animals. Price quotations of the materials were obtained in different states of the country and averaged. An initial frequency of horned animals of 92.16% was obtained based on the records of the Brazilian Association of Zebu Breeders. Selective breeding was found to be the best cost-effective scenario. This result differs from intensive production systems of dairy cattle in which traditional disbudding continues to be the best cost-effective scenario. The main explanation is the lack of difference in the price of Nelore semen from polled and horned bulls. Phenotypic selection for polled animals is the best cost-effective method, and it is in accordance with welfare practices. Care should be taken regarding the intensive use of few polled breeding animals in order to avoid inbreeding depression in other traits.

Genetic and phenotypic parameters for sexual precocity and parasite resistance traits in Nellore cattle.

Indicator traits of sexual precocity are widely used as selection criteria for the genetic improvement of beef cattle; however, the impact of selection for these traits on resistance to endoparasites and ectoparasites is unknown. Therefore, this study aimed to estimate the genetic and phenotypic parameters for indicator traits of sexual precocity and parasite resistance in Nellore cattle. The sexual precocity traits evaluated were probability of first calving (PFC) and scrotal circumference at 12 and 18months of age (SC12 and SC18). The resistance-related traits included tick (TC), gastrointestinal nematode egg (NEC), and Eimeria spp. oocyst (EOC) counts. (Co)variance components were estimated by Bayesian inference using multitrait animal models. The mean heritabilities for PFC, SC12, SC18, TC, NEC, and EOC were 0.23, 0.38, 0.42, 0.14, 0.16, and 0.06, respectively, and suggest that selection will change the mean values of these traits over time. The genetic and phenotypic correlations for most pairs formed by a precocity and a resistance trait were not different from zero, suggesting that selection for sexual precocity traits will not result in changes in resistance traits. Thus, selection for indicator traits of sexual precocity does not elicit unfavorable correlated responses in resistance to endoparasites and ectoparasites, and joint selection aimed at improving these traits can be performed using multitrait selection methods, when necessary.

High-intensity ultrasound improves color and oxidative stability of beef from grain-fed and pasture-fed Nellore cattle

This research aimed to evaluate the influence of high-intensity ultrasound (HIU) levels (control: 0; high: 747.79; ultra-high: 1344.17 Wcm−2) on pH, instrumental color (redness, R630/580, hue angle and chroma) and oxidative stability (lipid and protein oxidation) of Psoas major (PM) muscle from Nellore cattle raised in two feeding systems: grain and pasture. Using a structural equation modeling (SEM) approach, the relations (P > 0.05) between exogenous (HIU levels) and endogenous (pH, color, lipid and protein oxidation) variables were observed. In beef from grain-fed animals the pH was directly and negatively related to lipid oxidation (γ = −0.321), hue angle (γ = −0.847) and chroma (γ = −0.442) and protein oxidation (γ = −0.752). In PM from pasture-fed HIU exhibited a negative relation with lipid (γ = −0.144) and protein (γ = −0.743) oxidation, suggesting a possible positive influence on the oxidative stability of meat and a positive relation with redness (γ = 0.197) and R630/580 (γ = 0.379). The HIU positively influenced the color and oxidative stability of beef from Bos indicus cattle, and a synergistic effect of HIU and feeding system on beef from pasture-fed animals.

Characterization of Thermal Patterns Using Infrared Thermography and Thermolytic Responses of Cattle Reared in Three Different Systems during the Transition Period in the Eastern Amazon, Brazil.

In the Lower Amazon mesoregion, there are basically three types of production systems: the traditional (without shade and no bathing area), the silvopastoral (with shade and no bathing area), and the integrated (with shade and bathing area). It is considered that the type of production system influences the thermal comfort and productivity of cattle, so this research aims to evaluate the influence of these three types of production systems on the thermoregulation of Nellore cattle. The experiment was carried out on a rural property for raising cattle, located in Mojuí dos Campos, Pará, Brazil, during the transition period (June/July). Thirty bovine males (not castrated, aged between 18 and 20 months, average weight of 250 ± 36 kg, body condition score of 3.5, clinically healthy) were randomly divided into three groups: Silvopastoral System-SS (n = 10), Traditional System-TS (n = 10), and Integrated System-IS (n = 10). Climate variables were collected (air temperature (AT °C), relative humidity (RH %), wind speed (WS, m/s), solar radiation (SR), black globe temperature (BGT °C), and physiological parameters, such as respiratory rate (RR) and rectal temperature (RT)) at 6 a.m., 12 p.m., 6 p.m., and 12 a.m. to determine the thermal comfort situation of the animals. Thermographic images of the environment and animals were captured in order to obtain the body surface temperature (BST) through infrared thermography. The Benezra Thermal Comfort Index (BTCI), Environmental Stress Index (ESI), Equivalent Temperature Index (ETI), and Iberian Heat Tolerance Index (Iberian HTI) were used. The results showed that the silvopastoral system, with shading by chestnut trees and an ample vegetative area, presented better thermal conditions, with an average of 28.98 °C, in comparison with the traditional system (35.93 °C) and the integrated one (34.11 °C). It was observed that the body surface temperature of cattle did not differ significantly between the anatomical regions of the body and the studied systems (p > 0.05). As for the respiratory rate, the traditional system registered higher values, with an average of 41 movements per minute, indicating possible thermal stress (p < 0.05). The thermal comfort indices revealed that all systems presented moderate stress conditions during times of higher solar intensity. It is concluded that the silvopastoral system proved to be more favorable for cattle, providing shade and reducing thermal stress, which may have a positive impact on animal welfare and productivity in this region.

Feet and legs malformation in Nellore cattle: genetic analysis and prioritization of GWAS results.

Beef cattle affected by feet and legs malformations (FLM) cannot perform their productive and reproductive functions satisfactorily, resulting in significant economic losses. Accelerated weight gain in young animals due to increased fat deposition can lead to ligaments, tendon and joint strain and promote gene expression patterns that lead to changes in the normal architecture of the feet and legs. The possible correlated response in the FLM due to yearling weight (YW) selection suggest that this second trait could be used as an indirect selection criterion. Therefore, FLM breeding values and the genetic correlation between FLM and yearling weight (YW) were estimated for 295,031 Nellore animals by fitting a linear-threshold model in a Bayesian approach. A genome-wide association study was performed to identify genomic windows and positional candidate genes associated with FLM. The effects of single nucleotide polymorphisms (SNPs) on FLM phenotypes (affected or unaffected) were estimated using the weighted single-step genomic BLUP method, based on genotypes of 12,537 animals for 461,057 SNPs. Twelve non-overlapping windows of 20 adjacent SNPs explaining more than 1% of the additive genetic variance were selected for candidate gene annotation. Functional and gene prioritization analysis of candidate genes identified six genes (ATG7, EXT1, ITGA1, PPARD, SCUBE3, and SHOX) that may play a role in FLM expression due to their known role in skeletal muscle development, aberrant bone growth, lipid metabolism, intramuscular fat deposition and skeletogenesis. Identifying genes linked to foot and leg malformations enables selective breeding for healthier herds by reducing the occurrence of these conditions. Genetic markers can be used to develop tests that identify carriers of these mutations, assisting breeders in making informed breeding decisions to minimize the incidence of malformations in future generations, resulting in greater productivity and animal welfare.

Influence of nutritional management prior to adaptation to a feedlot diet on ruminal microbiota of Nellore cattle

Influence of nutritional management prior to adaptation to a feedlot diet on ruminal microbiota of Nellore cattle

Relationships between follicle and corpus luteum size and vascularization with ovulation, progesterone production, and pregnancy in Nellore beef cattle

Relationships between follicle and corpus luteum size and vascularization with ovulation, progesterone production, and pregnancy in Nellore beef cattle

Effects of estradiol cypionate dosage and body condition on reproductive performance of Nellore cattle synchronized for timed-artificial insemination

This experiment was designed to evaluate the effects of increasing doses of estradiol cypionate (ECP) and different body condition score (BCS) on reproductive performance of Bos indicus beef females assigned to a timed-artificial insemination (TAI) management. In this experiment, 1683 Bos indicus Nellore cows were blocked by parity and assigned to receive 1) an intravaginal P4 device (1.9 g of P4) and 2.0 mg of estradiol benzoate on day −11, 12.5 mg (i.m.) of dinoprost tromethamine, 300 IU (i.m.) of equine chorionic gonadotrophin, 0.6 mg (i.m.) of estradiol cypionate and CIDR withdrawal on day −2, followed by TAI on day 0 (n = 849; 0.6ECP) or 2) the same synchronization protocol with 1.0 mg of ECP on day −2 (n = 834; 1.0ECP). In both treatments, estrus expression was measured between days −2 and 0. Body condition score (BCS) was evaluated on days −11, 31, and 71 of the experiment and the BCS variation (Δ) was also determined between these timepoints. Transrectal ultrasonography was performed on days 31, 71, and 111 for pregnancy rate determination. All binary data were analyzed using cow as the experimental unit with GLIMMIX, whereas continuous variables were analyzed with the MIXED procedure of SAS. No treatment effects were observed on estrus expression rate. Treatment × BCS interactions were observed for pregnancy rates in all time points (days 31, 71, and 111), as 1.0ECP cows with a LOW BCS also had a greater P/AI than cows assigned to 0.6ECP. In summary, increasing the dose of ECP benefited the reproductive performance of Nellore beef cows with a reduced BCS (≤2.75), whereas no benefits were seen when the BCS was considered adequate (>2.75).

Efficiency of Amino Acid Utilization in Nellore Cattle Grazing Low-Quality Forage Supplemented with Different Sources of Nitrogen.

This study aimed to evaluate the effects of supplementation with non-protein nitrogen (NPN) or ruminal undegradable protein (RUP) on intake, digestibility, and amino acid (AA) use efficiency of Nellore cattle grazing during the dry season. Eight Nellore steers (12 ± 2 months old) were used in quadruplicate Latin squares (2 × 2). The animals were placed on Urochloa brizantha cv. Xaraés under continuous grazing. The treatments included the following: (1) urea supplementation (NPN) and (2) supplementation of corn gluten meal 60 (CGM, RUP). Animals supplemented with CGM showed higher intakes of dry matter (DM) supplement, total AA, essential AA, and individual AA. The supplementation did not affect the total AA digestibility, total AA flux, and the AA fluxes of microbial origin and RUP from the diet (p > 0.05). The ruminal microorganism origin flux of total AA to the duodenum was 44.5% and 52.7% for animals supplemented with NPN and CGM, respectively. Animals supplemented with CGM showed an increase in blood concentrations of isoleucine (+19.09 μmol/L), cystine (+27.29 μmol/L), and albumin (+0.11 g/dL) (p < 0.05), but this increase was not accompanied by an improvement in N use efficiency of steers (p > 0.05). RUP supplementation via CGM can be an efficient nutritional strategy to enhance the intake and absorption of AA by Nellore cattle grazing low-quality forage during the dry season.

A Comparative Study on Meat Quality Characteristics of Murrah Buffalo and Nellore Cattle Commercialized in Southeastern Brazil

Murrah buffalo and Nellore cattle meat commercialized in Southeastern Brazil were evaluated during aging. Ribeye steaks (Longissimus thoracis muscle) were analyzed during four wet aging times (0, 7, 14, and 21 days) stored at 2 ± 1 °C. The water holding capacity (WHC) decreased (p &lt; 0.05) during aging (0.41 to 0.28), with buffalo meat having (p &lt; 0.05) lower pH and a higher WHC than beef. Lower myofibrillar fragmentation index and shear force (WBsSF) values were observed (p &lt; 0.05) in buffalo meat. Soluble collagen content increased (p &lt; 0.05) during aging, with lower (p &lt; 0.05) values in buffalo meat. Buffalo meat had (p &lt; 0.05) higher metmyoglobin percentages, being darker (lower L* values) and with a higher red color intensity (higher C* values) than beef. There was a difference between buffalo meat and beef volatile compound profiles, with greater variation in the beef profile during aging, probably due to differences in lipid oxidation and proteolysis. It can be concluded that buffalo meat is very similar to that of Zebu cattle, with less variation during aging and greater tenderness than beef. Therefore, buffalo meat is a good alternative source for fresh marketing and processing of high-quality meat products.

Identification of candidate lethal haplotypes and genomic association with post-natal mortality and reproductive traits in Nellore cattle

The wide use of genomic information has enabled the identification of lethal recessive alleles that are the major genetic causes of reduced conception rates, longer calving intervals, or lower survival for live-born animals. This study was carried out to screen the Nellore cattle genome for lethal recessive haplotypes based on deviation from the expected population homozygosity, and to test SNP markers surrounding the lethal haplotypes region for association with heifer rebreeding (HR), post-natal mortality (PNM) and stayability (STAY). This approach requires genotypes only from apparently normal individuals and not from affected embryos. A total of 62,022 animals were genotyped and imputed to a high-density panel (777,962 SNP markers). Expected numbers of homozygous individuals were calculated, and the probabilities of observing 0 homozygotes was obtained. Deregressed genomic breeding values [(G)EBVs] were used in a GWAS to identify candidate genes and biological mechanisms affecting HR, STAY and PNM. In the functional analyses, genes within 100 kb down and upstream of each significant SNP marker, were researched. Thirty haplotypes had high expected frequency, while no homozygotes were observed. Most of the alleles present in these haplotypes had a negative mean effect for PNM, HR and STAY. The GWAS revealed significant SNP markers involved in different physiological mechanisms, leading to harmful effect on the three traits. The functional analysis revealed 26 genes enriched for 19 GO terms. Most of the GO terms found for biological processes, molecular functions and pathways were related to tissue development and the immune system. More phenotypes underlying these putative regions in this population could be the subject of future investigation. Tests to find putative lethal haplotype carriers could help breeders to eliminate them from the population or manage matings in order to avoid homozygous.