Beef Bulls Research Articles

Effects of whole cottonseed supplementation on performance, semen quality, and manganese superoxide dismutase concentrations in blood and semen of beef bulls

This research aimed to determine the effects of whole cottonseed on performance, semen quality, and manganese superoxide dismutase (MnSOD) concentrations in the blood and semen of beef bulls. In a completely randomized design, 46 (BW = 457 ± 12 kg; 16–18 mo old) Angus bulls were stratified by BW and randomly assigned to 1 of 3 treatments: DD (n = 14, control; 3.18 kg/d dried distillers grain), WD [n = 16; 1.59 kg/d whole cottonseed (0.56 and 0.82% free gossypol in yr 1 and 2, respectively) and 1.59 kg/d dried distillers grain], or WW (n = 16; 3.18 kg/d whole cottonseed). Bulls were weighed and blood and semen were sampled on d 0, 30, and 60. Body weights and morphological characteristics of spermatozoa were measured in both years, and MnSOD concentrations of blood and semen were measured in yr 1. There was a treatment effect for ADG (P = 0.002) as bulls fed WW had a decreased (P < 0.03) ADG compared with bulls fed WD and DD. A time effect was observed for scrotal circumference (P < 0.001). Scrotal circumference measurements increased on d 60 compared with d 0 and 28 (P ≤ 0.02). There was no time main effect for percentage of spermatozoa with other abnormalities (P = 0.87); however, there was a treatment effect (P = 0.04). Bulls in the WW treatment had fewer other abnormalities than bulls in DD (P = 0.01) but were not different than WD (P = 0.27). Whole cottonseed did not affect reproductive parameters measured in this study or blood and semen concentrations of MnSOD. According to these results, WCS supplemented to beef bulls at 0.7% of BW for 60 d may not negatively affect semen quality or MnSOD concentrations in the blood or semen.

BIOLOGICAL VALUE AND TECHNOLOGICAL INDICATORS OF MEAT IN BEEF BULLS OF DIFFERENT GENOTYPES IN THE CONDITIONS OF THE AGRICULTURAL HOLDING "BAISERKE-AGRO"

Annotation The most important biological feature of beef bulls is their ability to consume and process a large amount of cheap low-nutritional feed, including waste from crop production and the food industry, into valuable food products for humans. The meat products and leather raw materials obtained at the same time are of high quality. The development of new directions in breeding, for example, early prediction of the productive qualities of livestock, contributed to a greater opportunity for selection, a reduction in the interval between generations and more effective breeding of cattle in the meat direction of productivity. We need animals that have requirements that provide for obtaining the most "economical animals", combining in their genotype the strength of the constitution and high productivity, good fattening and meat qualities, resistance and immunity to stress, having good adaptive abilities to living conditions and economic use. In other words, it is necessary to create animals with high productivity and well adapted to intensive use. The aim of the research was to improve and optimize breeding methods to increase the rate of genetic progress of different beef breeds of cattle. Based on the interaction of genotypes, to determine effective methods for improving the breeding and productive qualities of meat breeds of different genotypes to increase the production of high-quality beef. This article presents the results of studies of meat productivity of beef bulls of different genotypes in the conditions of the agricultural holding "Baiserke-Agro". According to the results of the research, the quality of carcasses and slaughter indicators, the morphological composition of carcasses and individual anatomical parts, the chemical composition of meat and the energy value of raw fat were established. The conducted studies contributed to the fullest realization of the genetic potential of the productivity of the Aberdeen Angus, Hereford and Kazakh white-headed breeds, as a result, an additional reserve for obtaining high-quality beef was revealed. The proposed methods and techniques of organizing the breeding process allowed to create highly productive beef cattle in the conditions of the agricultural holding "Bayserke-Agro", which contributed to reducing the cost of 1 kg of live weight gain by 5-8% and obtaining additional profit for 1 head by 14-16%. &nbsp; &nbsp

Fattening of bulls of Aberdeen-Angus Kalmyk and Charolais breeds in conditions of environmentally safe feeding and keeping

In a scientific and economic experiment on bulls of the Aberdeen-Angus, Kalmyk and Charolais breeds of pasture fattening in the foothill raw material zone of the Labinsk district of the Krasnodar region, the productivity, interior, quality and safety of meat raw materials were studied in a comparative aspect. At the fattening complex of the agricultural company, six-month-old bulls of Aberdeen-Angus, Kalmyk and Charolais breeds were formed into three groups by age according to the principle of analogues (n=12), which were raised from birth using the technology of specialized beef cattle breeding. The first group - Aberdeen-Angus bulls, the second - Kalmyk bulls and the third - Charolais bulls, which had a live weight at the beginning of fattening 189.5 ± 13.8; 175.5±11.5 and 177.1±7.6 kg, respectively. The results of the slaughter of bulls of three breeds revealed a direct relationship between pre-slaughter live weight and slaughter indicators. The pre-slaughter weight of Charolais bulls and, to a lesser extent, Aberdeen-Angus bulls was significantly higher than the mass of Kalmyk bulls. The difference between the slaughter rates of the three breeds of beef bulls is significant in terms of such indicators as slaughter yield, boneless beef yield with the advantage of carcass morphology of Charolais bulls. The slaughter yield was higher in bulls of the Charolais breed compared to groups 1 and 2 by at least 3.2 % and amounted to 69.5 %. In the study of the chemical composition of muscle tissue, a reliably maximum proportion of protein and a minimum proportion of fat in the longissimus muscle of carcasses of Charolais bulls were determined, which amounted to 21.7 and 7.6 %, respectively. A direct positive relationship was determined between meat productivity and the mass fraction of protein in the muscles of bulls of three breeds with such interior indicators as the mass fraction of total protein, protein index. The results of the research allowed to conclude that the biological status of animals has a significant impact on meat productivity, technological properties and the biological value of meat raw materials necessary for the production of baby and functional nutrition.

Drinking water chlorination in dairy beef fattening bulls: water quality, potential hazards, apparent total tract digestibility, and growth performance

The first study aimed to evaluate the effect of drinking water disinfection (chlorination: NaClO 15%) and conditioning (acidification: H3PO4 diluted 1:5 in water) on water quality, water and feed consumption, apparent total tract digestibility, and its potential hazardous effects on Holstein bulls fed high-concentrate diets. Twenty-four animals (221 ± 20.9 kg of BW, and 184 ± 9.9 days of age) were individually assigned to one of four treatments according to a 2 × 2 factorial arrangement: conditioning (with or without acidification) and disinfection (with or without chlorination). The entire study lasted 210 days. Physicochemical and microbiological water quality, water and feed consumption, haematological and biochemical blood parameters, and apparent total tract digestibility were measured; data were analysed via a mixed-effects model. Chlorination and acidification increased (P = 0.02) free residual chlorine in water, and chlorination reduced (P = 0.01) total coliform and Clostridium perfringens counts in water. Treatment did not affect water consumption, total DM intake, or blood parameters. At the beginning of the study, NDF digestibility decreased (P = 0.04) with acidification, however, this was restored at the end of the study. The second study evaluated the potential benefit of drinking water chlorination and acidification on the performance of crossbred Holstein bulls fed high-concentrate diets under commercial conditions. Ninety-six animals (322 ± 35.0 kg of BW, and 220 ± 14.2 days of age) were allocated into six pens assigned to one of the two treatments: untreated drinking water or drinking water treated with chlorination and acidification for a total of 112 days. Physicochemical and microbiological water quality, water and concentrate consumption, eating behaviour, growth performance, and carcass quality were analysed via a mixed-effects model. Water conditioning and disinfection increased (P = 0.01) free residual chlorine concentration and reduced (P = 0.04) total coliform count in water. Although water consumption and eating behaviour were similar between treatments, water conditioning and disinfection increased average daily weight gain (P = 0.03), BW before slaughter (P = 0.01), and hot carcass weight (P = 0.01). In conclusion, drinking water chlorination and acidification in fattening dairy beef bulls is recommended as it improves growth performance without any detrimental side effects on health or nutrient digestibility.

Effect of Epidermal Growth Factor (EGF) on Cryopreserved Piedmontese Bull Semen Characteristics.

The purpose of this study was to determine the effect on fresh and post-thaw beef bull semen quality of the supplementation of epidermal growth factor (EGF) to the semen extender at various concentrations (0-control, 50, 100, 200, and 400 ng/mL). For 8 weeks, sperm was collected from four fertile bulls, yielding a total of 32 ejaculates. Semen samples were pooled, diluted with Bullxcell® extender, and then cooled, equilibrated, and frozen. After thawing, semen was tested for motility and velocity parameters. Furthermore, semen was evaluated for vitality, integrity, mitochondrial and antioxidant (SOD) activities, mucus penetration distance, and in vitro fertilizing capability. The supplementation with EGF prior to cryopreservation improved the total sperm motility at various concentrations over long incubation periods (from 1 to 4 h). Interestingly, EGF addition improved both progressive and rapid motility, particularly at 50, 200, and 400 ng/mL. In addition, EGF, primarily at 200 and 400 ng/mL, significantly increased several velocity parameters after different incubation periods. We can conclude that adding EGF to bull sperm extender before cryopreservation has a positive stimulatory effect on sperm motility without affecting vitality, integrity, or in vitro fertilizing capability.

Rumen fermentation, methane concentration, and blood metabolites of cattle receiving dietetical phytobiotic and cobalt (II) chloride.

Ensuring the genetic potential of ruminants through nutrition studies using medicinal plants and trace element metals is an urgent task. This study aimed to study the effect of Artemisia absinthium L. (Asteraceae) herb plant separately and in combination with cobalt (II) chloride (CoCl2) chelate compounds on the course of metabolic processes in the rumen, methane concentration, and biochemical blood parameters in bulls. Control group (BD: Basal diet); experimental Group I - BD + A. absinthium herb at a dose of 2.0 g/kg dry matter (DM), experimental Group II - BD + A. absinthium herb at a dose of 2.0 g/kg DM + CoCl2 (1.5 mg/kg), and experimental Group III - BD + CoCl2 were set (1.5 mg/kg). The study was conducted on 16 beef bulls (Kazakh white-headed breed) aged 13-14 months, with an average live weight of 330-335 kg. Enzymatic processes in the rumen were studied, including the level of volatile fatty acids (using the gas chromatography method), nitrogen and its fractions (using the Kjeldahl method), methane concentration, and morphological and biochemical blood composition. There was a decrease in the concentration of acetic acid in experimental group I (15.9%) (p < 0.05) and in the III group (60.3%) and propionic acid in all experimental groups by 5.6%-47.3% (p < 0.05). Feeding A. absinthium herb as part of the diet of experimental Group I contributed to a decrease in methane concentration by 17.8% (p = 0.05) and the lowest methane concentration was noted for experimental Group III. It was less than in control by 59.1% (p < 0.05). An increase in the concentration of glucose, total protein, and creatinine was found in the experimental groups (p < 0.05). The digestibility of organic matter (3.5%), crude fiber (3.6%), and hemicellulose (11.0%) increased with the feeding of A. absinthium herb. Thus, using biocomplexes based on A. absinthium herb and CoCl2 do not harm the rumen fermentation of cattle. Still, further microbiome studies are required to evaluate the effects of A. absinthium on cattle properly.

Satisfactory breeding potential is transiently eliminated in beef bulls with clinical anaplasmosis

BackgroundNatural service breeding is common in U.S. cow-calf operations. Diseases impacting bull reproductive performance have significant economic consequences for producers. Anaplasmosis may be an underappreciated cause of poor reproductive performance in bulls. The primary systemic effects of bovine anaplasmosis including anemia, fever, and weight loss, can all result in unsatisfactory reproductive performance. The objective of this pilot study was to evaluate breeding soundness examination (BSE) outcomes and clinical changes in bulls during and upon resolution of clinical anaplasmosis. Anaplasma marginale-challenged bulls were observed for clinical disease and infection progression and changes in breeding soundness compared to uninfected control bulls for 16 weeks.ResultsAll Anaplasma marginale-challenged bulls were PCR-positive, seropositive, and showed clinical signs by 3-, 17-, and 24-days post-challenge, respectively. Clinical signs of anaplasmosis included pallor, icterus, fever (≥ 40.2 °C), and weight loss. Acute anemia was observed in all challenged bulls with PCV nadirs ≤ 18% and peak percent parasitized erythrocyte ≥ 50%. Decreased scrotal circumference and poor semen quality (e.g., increased percentage of abnormal spermatozoa, decreased progressively motile sperm), were initially observed within days after onset of clinical anaplasmosis signs and continued weeks beyond disease resolution. Control bulls remained negative for A. marginale.ConclusionThis pilot study demonstrates that clinical anaplasmosis reduces breeding soundness in beef bulls. Anaplasmosis should be considered as a differential for bulls with decreased semen quality, especially within endemic areas. A 90 day or greater retest window is recommended for bulls of unsatisfactory breeding potential recently recovered from clinical anaplasmosis.

1 Characterization of Mature Beef Bull Seminal Fluid and Blood Serum Metabolome During a 65-Day Breeding Season

Abstract The American beef bulls have been neglected in terms of animal science research. Metabolomics is a respected for of science that will aid in developing hypothesis for future research in beef bulls. The objective of this study was to identify metabolites within a 65-day breeding season that were affect by breeding season duration and workload. Over a two-year period, 8 purebred Angus bulls owned and housed by the Cal Poly beef unit were surveyed using serum (collected via the coccygeal vein) and seminal fluid (collected via electroejaculation) at the beginning and end of a 65-day post-AI breeding season. Samples underwent HPLC-MS to observe metabolites within the fluids. Data were stratified for sample day and workload and compared using t-test for day and ANOVA for workload. Within serum, 8 metabolites of interest were observed. Effects included differences between workload groups in the abundance of guanosine (P = 0.01) a metabolite associated with purine metabolism. Within seminal fluid, 13 metabolites of interest were observed including Inosine, a metabolite also involved in purine metabolism and fluctuating based on workload (P = 0.05). Purine metabolism will be of interest to future research of beef bulls.

Performance and enteric methane emission of growing beef bulls from different genetic groups subjected to two supplementation strategies grazing tropical grass in the rainy season

Improving livestock production through nutrition and breeding can increase efficiency and has the potential to mitigate methane (CH4) emissions. Additionally, supplementing beef cattle in the rainy season balances the dietary protein:energy (P:E) ratio, which can increase animal performance and reduce energy losses from CH4 production. Therefore, the objective of this study was to evaluate the effect of supplementation strategy (SS) and genetic group (GG) on the intake, digestibility, performance, and enteric CH4 emissions of growing beef bulls grazing tropical grass during the rainy season. One hundred sixty-two growing beef bulls averaging (mean ± SD) 10 ± 2 months old and 262 ± 31 kg of initial body weight (BW) were distributed, according to their BW, in a randomized complete block design in a 2 × 3 factorial arrangement. Factors included (1) two SSs (mineral supplementation at 0.3 g/kg of BW per day and a corn-based supplementation at 3 g/kg of BW per day) and (2) three GGs (Nellore [NN], ½Senepol½Nellore [SN], and ½Angus½Nellore [AN]). Animals were allocated in 12 paddocks composed of Urochloa brizantha (A. Rich.) Stapf. cv. Xaraés for 99 days during the rainy season. Regardless of the GG, the intakes of total DM, supplement DM, OM, CP, aNDFom, EE, and NFC were increased in animals supplemented with a corn-based supplement. The SN bulls had a greater digestibility of DM, OM, and CP, and animals supplemented with a corn-based supplement had greater CP and EE digestibility. There was an interaction between GG and SS for NFC digestibility, which was decreased in AN animals fed a corn-based supplement. However, the corn-based supplementation improved the animal’s performance and carcass characteristics as demonstrated by the increase of final BW (kg), ADG (kg), REA (cm2), and FT (mm). Moreover, NN animals fed a corn-based supplement showed an increase in ADG (kg). An interaction between SS and GG was observed for GPH (kg/ha) and CaG (kg), with the greatest values observed in NN and SN animals supplemented with a corn-based supplement. Enteric CH4 emissions (g/d, g/kg of DMI, and g/kg of dOM) were lower in animals fed a corn-based supplement. A decrease in CH4 emissions (g/d) was observed in SN compared to NN animals. In addition, there was an interaction between SS and GG for CH4 emissions (g/kg of CaG), with the lowest values for NN and SN animals supplemented with a corn-based supplement. Taken together, our results demonstrate that corn-based supplementation is an effective nutritional strategy for use in the rainy season, especially for NN and SN genetic groups, to improve animal’s performance and carcass characteristics and to decrease enteric CH4 emissions, per unit of product, of growing beef bulls grazing tropical grass.

Invited Review: Using whole cottonseed and cotton harvest residue in southeastern US beef cattle diets: Quality, intake, and changes in feed characteristics

Cotton ( Gossypium sp.) is grown on over 4.5 million hectares in the United States annually. This article provides an overview of cotton industry changes and their influence on whole cottonseed and cotton residue quality and use in beef cattle operations in the southeastern United States. Whole cottonseed may vary depending on cotton growing and harvest conditions, seed composition, and ginning technologies. Most cottonseed is hand fed to beef cattle at a set feeding rate to control fat intake. However, there is variation in the literature in on-farm cottonseed feeding strategies and potential use of whole cottonseed in beef bull diets. Cotton residues are often used as a roughage alternative. Strategies to expand the use of cotton residues include integrated crop-livestock systems, gin byproduct baling applications, and evaluation of chemical residues to determine feeding safety. Periodic characterization of seed protein, fat, and gossypol can refine beef cattle feeding strategies. Grazing cotton field residue can reduce hay needs in beef cattle diets. There is limited information on animal growth performance, health, and safety of beef cattle fed cotton residues, which may potentially contain detectable levels of pesticides or herbicides. Use of whole cottonseed and cotton residues benefits both the cotton and beef cattle industries. Future research to more closely mimic on-farm beef nutritional management strategies may expand the use of whole cottonseed as a supplement. Quality evaluation of cotton byproducts ensures greater accuracy in ration development and may help elucidate threshold values for establishing safety of use.

Bull selection and management in extensive rangeland production systems of California: a producer survey.

California's approximately 660,000 head of beef cattle are highly dependent on range bulls used to produce offspring that can perform across the state's diverse ecological regions. Bulls need to be functional on rugged coastal landscapes, rolling foothills, deserts, and in high-elevation terrain. Few data exist that indicate factors related to selection, maintenance, and longevity of bulls used in rangeland landscapes. Objectives herein, were to assess factors influencing bull purchasing, management, and culling decisions of California beef producers. Surveys were mailed to the California Cattlemen's Association membership (N = 1,410) with ~ 16% response rate (N = 227). Mean age and years of bull selection experience of respondents was 61 ± 1 yr and 27 ± 1 yr, respectively. Respondents managed cattle on a total of 694,949 hectare of owned, private leased, and leased public rangelands in California and surrounding states. Cow-calf herd size was 333 ± 92 head and bull battery averaged 18 ± 2 head with average bull longevity of 5 ± 1.3 yr. The average price paid for bulls in the last 2 yr was $5007 ± 163.33, while the highest price paid in the last 5 yr was $7291 ± 335.40. Survey responses were used to define current factors driving management after purchase and for subsequent breeding seasons. After bull purchase, 48% of producers turned bulls out directly with females, while 52% held bulls until the following breeding season. Additionally, most producers (70%) did not manage bulls to reduce condition after purchase. Semen quality analysis, a major component of a breeding soundness exam, was evaluated annually by 45% of respondents, while 20% of respondents never evaluated semen quality. Respondents indicated bull age (35%) and structural soundness (29%) as the most common factors for culling bulls. This research shows that despite the variability in operation demographics, there were similarities in beef bull selection and management across the state. Additionally, these data suggest the need for additional research focused on bull selection and management to maximize producer investment in reproduction.

Genetic evaluation of the scrotal circumference of beef bulls in the Czech Republic

The objective of the present study was to estimate the genetic parameters for the scrotal circumference of bulls of beef breeds in the Czech Republic. The used database for the years 1996–2020 comprised information on the scrotal circumference measurements from 22 065 bulls of 19 pure breeds and crossbred animals of the Beef Simmental, Charolais, and Hereford breeds. After adjustments, the database contained 16 404 records. To test the influence of systematic fixed effects, the GLM/SAS procedure using the least-squares method was applied. The contemporary group, weight and age of the bulls were included as significant systematic environmental effects (&amp;lt; 0.05). The genetic parameters were determined by a single-trait model using the AIREMLF90 program. The heritability coefficient of the scrotal circumference was 0.27. Environmental correlations of the scrotal circumference with the bull weight were moderate and positive (r = 0.2), but the correlations between the age in days and the scrotal circumference were almost zero (r = 0.03). The results indicate that the scrotal circumference of beef cattle breeds provides sufficiently high genetic variability that can be used to identify individuals with an above-average circumference and, in this way, increase the probability of selection of a young bull with a better reproduction potential.

PSII-A-2 Correlations between Reactive Oxygen Species and Functional Measurements of Spermatozoa from Beef Bulls

Abstract Reactive oxygen species (ROS) have effects on characteristics of spermatozoa, including mitochondrial membrane potential, acrosomal integrity, and structural abnormalities that can influence spermatozoa function. The objective was to determine correlations between sperm response to ROS and functional sperm measurements using ejaculates collected as part of bull breeding soundness exams (BSE). Semen samples were collected from Angus and Charolais bulls (403 ± 11 d of age; n=46) over three days during yearling BSEs. A veterinarian evaluated spermatozoa for percent motility and normal morphology, and percentage progressive motility was measured using an iSperm® analyzer. If ejaculates met minimum thresholds for passing a BSE, they were diluted to 70 million cells/mL using BoviFree® and sent overnight for flow cytometry evaluation. Flow cytometry assays including acrosome and cell membrane integrity, mitochondrial energy potential, and oxidation status. Data were analyzed using Pearson’s correlation coefficients in SAS. Percentage live spermatozoa with positive ROS status was correlated (r = 0.53; P &amp;lt; 0.001) with percentage progressive motility. Percentage live spermatozoa with negative ROS status was moderately correlated with percentage spermatozoa exhibiting secondary abnormalities (r = 0.33; P = 0.02) and tended to be lowly correlated (r = 0.28; P = 0.06) with percentage spermatozoa exhibiting primary abnormalities. Percentage live spermatozoa that had disrupted acrosomes was strongly correlated (r = 0.66; P &amp;lt; 0.001) with percentage live spermatozoa with negative ROS and also moderately negatively correlated (r = -0.31; P = 0.04) with percentage live spermatozoa with positive ROS. Percentage live spermatozoa with positive ROS status was correlated (r = 0.58; P &amp;lt; 0.001) with percentage of spermatozoa with active mitochondrial membranes. Live spermatozoa with positive ROS were strongly correlated (P&amp;lt; 0.001) with live spermatozoa (r=0.94) and live spermatozoa with intact acrosome (r=0.92). These data confirm previous research that shows the detrimental effects of ROS on spermatozoa function.

367 Characterization of the Seminal Microbiota in Beef Bulls Subjected to Different Rate of Gains Using 16S Rrna Gene Sequencing and Culturomics

Abstract Increasing evidence supports the existence of a microbial community in bovine semen, and that this seminal microbiota may influence not only the male reproductive health, but also female and offspring health through microbial transfer. In this study, we evaluated seminal microbiota in beef bulls (BW= 503±7.2 kg) fed a common diet to achieve moderate (1.13 kg/d) or high (1.80 kg/d) rates of weight gain. Semen samples were collected at day 0 and day 112 of dietary intervention (n = 19 per group), and post-breeding (n = 6) using electroejaculation and the microbiota assessed using 16S rRNA gene sequencing, quantification of total bacteria by qPCR, and viable bacteria culturing. A complex and dynamic microbiota was detected in the semen, and the community structure changed significantly over the course of the study (R 2 = 0.126, P &amp;lt; 0.001) but remained unaffected by the dietary treatment (P &amp;gt; 0.05). Microbial richness (number of ASVs) increased from d0 (253 ± 12) to d112 (293 ± 14) while diversity (Shannon index) was reduced (P &amp;lt; 0.05). Twenty-seven bacterial phyla were identified across all samples, with Fusobacteriota (36.3%), Bacteroidetes (30.4%), Firmicutes (17.1%) and Actinobacteriota (14.9%) being the most predominant phyla. Total bacterial load declined over time (P &amp;lt; 0.05). Diet had no effect on alpha diversity metrics, microbial composition, or total bacterial concentration (P &amp;gt; 0.05). A total of 364 bacterial isolates were recovered under aerobic (n = 220) and anaerobic (n = 144) culturing conditions. These isolates represented 48 different genera within the Firmicutes (60%), Proteobacteria (25%), Actinobacteria (9%), Bacteroidetes (4%) and Fusobacteriota (2%) phyla. Bacillus, Staphylococcus, Escherichia, Enterococcus and Arthrobacter were the predominant genera. Overall, our results suggest that bovine semen harbors a rich and complex microbiota which changes over time but appears to be resilient to differential gains achieved via common diet.

PSXII-9 Application of Machine Learning Algorithms to Estimate Tropical Pasture Biomass Based on Satellite Images

Abstract The proper quantification of forage allowance for ruminants in grass-based production systems has always been challenging. At the field scale, pasture management based on ground-level measurements, such as clipping or plate meter, is labor intensive and hampers the assessment of spatial and temporal variability. On the lookout for a solution, this study aimed to estimate marandu palisade grass forage mass based on satellite images using two machine learning (ML) algorithms, Multiple Linear Regression (MLR) and Artificial Neural Network (ANN). The experimental area comprised Marandu palisade grass pasture (Brachiaria brizantha ‘Marandu’), summing 33 paddocks (42 ha), receiving or not N fertilization. Pastures were managed under continuous stocking to maintain grazing height fixed at 25 cm during the growing season, using the put-and-take methodology with young beef bulls. Field dataset collection (total forage mass and morphological composition) and satellite images were assessed from Dec/2015 to Mar/2019 during the growing or wet season. The satellite images (Landsat-8 and Sentinel-2) were downloaded from US Geological Survey (USGS, http://earthexplorer.usgs.gov). Six spectral bands (Bd) and five vegetation indices (VI, Table 1) were used as input variables to MLR and ANN models. Datasets were randomly divided into a training set (80%) and a testing set (20%). Analyses were run in Python 3 (version 3.7). ML models are generally data-driven and require a large amount of data for better performance, and the best accuracy was achieved by using all Bd and VIs as input variables for both models (Table 1). In general, ANN produced better estimates than MLR models. Bd+VI better predicted leaf mass than total forage mass. Our results show that remotely sensed observations, based on satellite images, are a promising and effective tool for tropical grassland monitoring and management under continuous stocking rates. São Paulo Research Foundation (FAPESP) (grant ≠15/16631-5; 17/18750-7; 20/14367-7).

Comparison between chlorhexidine and povidone-iodine solutions for flushing the preputial cavity on penile mucosa and semen bacterial counts in beef bulls

The objectives of the present study were to estimate the number of colonies forming units (CFU) from penile mucosa and semen, the effect of two antiseptic solutions used to flush the preputial cavity to reduce the bacterial counts from those sites, and compare them. Six clinically healthy bulls between 15 and 16 mo old declared satisfactory potential breeders were used. A prospective, randomized, and controlled cross-over design was performed, in which each bull was first sampled from the penile mucosa and semen without treatment (control group) and 24 h later, after antiseptic preputial flushing (treated group). In the treated group, the preputial area was cleaned, the preputial hair was cut, urination was stimulated, prepuce area was scrubbed twice, and the preputial cavity was flushed with either 1% of povidone-iodine solution (POI; 500 mL) or 0.05% chlorhexidine digluconate (CHG; 500 mL), maintained for 10 min. Then, the preputial cavity was emptied and flushed with 500 mL of sterile saline solution. Next, the accessory sexual glands were massaged per rectum. Finally, protrusion, erection, and ejaculation were obtained by electroejaculation, and samples from penile mucosa and semen were collected for microbiological culture. The number of CFU was determined for each sample by enumerate total aerobic bacteria using Standard Plate Surface Count cultured for 48 h. In the first replicate, half of the bulls were treated with CHG, and the other half were treated with POI. After 58.8 ± 5.3 days (x ± SD) of wash-out period, the treatments were reverted, and the same protocols were applied again. In the control group, the median number of CFUs from the penile mucosa was 750,000 (range from 60,000 to 1,800,000) and the median number of CFUs in semen was 8,000,000 (700,000–45,000,000). The CFU in semen was higher than the penile mucosa (P = 0.005). Both antiseptic solutions reduced the median number of CFUs on the penile mucosa to 915 (P = 0.002) and in semen to 1,680 (P = 0.002). The antiseptic effect on the penile mucosa was higher for CHG solution (490) than for POI solution (6,650; P = 0.05). The antiseptic effect on semen of CHG was also greater (200) than for the POI solution (31,000; P = 0.05). It can be concluded that the median number of CFU was higher in semen compared with penile mucosa, and flushing the preputial cavity either with 0.05% CHG or 1% POI maintained for 10 min reduced the number of CFUs from penile mucosa and semen. The level of antiseptic activity was higher for CHG than for POI.

Feeding strategy during growing phase on the performance and carcass traits in beef bulls finished on the pasture.

The objective of this study was to evaluate the performance, feed intake, carcass traits, and economic aspects of cattle fed different levels of supplementation during the growing phase (mineral supplementation-MS; low protein supplementation-PS, at 0.15% of body weight (BW); and a high protein-energy supplementation-PES at 0.40% of BW) and finished on the pasture with concentrate supplementation at 1.6% of BW. Ninety bulls were distributed in a completely randomized design and allocated into paddocks predominantly composed of Urochloa brizantha cv. Marandu grass. During the finishing phase, cattle were managed in paddocks of Urochloa decumbens grass. The average daily gain (ADG) and total weight gain during the growing phase were not different between animals fed PS (0.670kg/day; 57.1kg, respectively) and PES (0.730kg/day; 62.4kg, respectively), but both differed significantly from those supplemented with MS (0.540kg/day; 45.1kg). There was no difference between groups for average daily gain and total weight gain during the finishing phase (0.600kg/day; 48.3kg) and the same response was observed for carcass yield (55.18%, on average). However, bulls fed PES had higher hot carcass weight compared with those supplemented with MS and PS. Protein supplementation (0.15% of BW) and protein-energy supplementation (0.40% of BW) improved beef cattle performance during the growing phase. However, supplementation during the growing phase has a small impact on cattle performance in the finishing phase, although protein-energy supplementation at the growing phase improves the hot carcass weight and carcass traits during the finishing phase.

The Colour, Composition and Eating Quality of Beef from Late- or Early-Maturing Suckler Bulls Finished at Pasture with or without Concentrate Supplementation.

Simple SummaryConsumers of beef are increasingly interested in how it is produced. There is a perception that grass-based systems of production have enhanced animal welfare and are more environmentally friendly than conventional systems. This has resulted in the development of “grass-fed” labelled beef which captures a premium in the marketplace. Bulls have traditionally been considered unsuitable for grass-based production systems, but they have growth advantages when compared with steers. However, eating quality or palatability, is a major influence on the decision of the consumer to continue to purchase beef, as is the colour of beef in the display case. There is a view in the meat industry that bull carcasses must achieve a threshold level of fatness for beef to be acceptable to the consumer. This is a challenge if bulls are of late-maturing breed types, but early maturing breed types might be more suited to a grass-based production system. Both breed types were compared and whether supplementary concentrates are required to meet the industry fatness specification. The findings indicate that achieving this specification was not required to ensure acceptable eating quality and that either breed type can be used, without supplementation, to access the lucrative “grass-fed” beef market.Carcasses from pasture-finished early-maturing (EM), rather than late-maturing (LM), breed bulls may be more suited to meet the minimum carcass fatness classification of 2+ (6.0 on a 15-point scale) required for some markets. The comparative colour and eating quality of beef from grass-fed bulls of different maturities are unknown. Sixty yearling suckler-bred bulls were assigned to a 2 (maturities: EM and LM) × 2 (finishing strategies: grass only (G0) or grass + 4.0 kg concentrate daily (GC)) factorial design. Bulls were at pasture from 7 April, concentrates were introduced (or not) 97 days later, and bulls were slaughtered at 192 d post-turnout (approximately 19 mo of age). Carcass fat scores averaged 5.02, 6.20, 6.33 and 7.30 for LMG0, LMGC, EMG0 and EMGC bulls, respectively. Muscle colour did not differ between treatments. Muscle from LM had lower intramuscular fat concentration, collagen solubility and a tendency (p < 0.1) towards lower ratings for tenderness, texture, and acceptability of 14 d aged beef. Concentrate supplementation decreased the ratings for muscle tenderness but ratings for acceptability were not affected. Achieving the minimum carcass fatness was therefore not required to produce beef of acceptable eating quality and suckler bulls can access the “grass-fed” beef market.

Content and gain of macro minerals in the empty body and body tissues of growing bulls

This research aimed to generate basic data for specifying the macro mineral requirements of beef bulls. Hence, the contents of the macro minerals calcium, phosphorus, sodium, potassium, sulfur, and magnesium in the empty body and body tissue fractions of growing Fleckvieh (German Simmental) bulls with 120–780 kg live weight were determined. Results were used to calculate mineral gain rates in bulls within a wide weight range from 100 to 800 kg live weight. Calcium and phosphorus represented the largest shares in the animals' bodies. Body mineral content changed during animal growth due to progressing bone mineralization and increasing amounts of fat in all body tissues. Peak mineral gain rates were observed for calcium, phosphorus, and magnesium during the 200–400 kg live weight range. The gain rates of sodium, potassium, and sulfur declined steadily during cattle growth. The provided data allow to adjust the existing values of net mineral requirements of growing Fleckvieh bulls within the factorial requirement calculation method.

Influence of tropical, subtropical, and temperate climate conditions on seminal redox status and sperm quality parameters in breeding bulls

This study evaluated the effect of climate change on andrological parameters of beef bulls raised under tropical, subtropical, and temperate conditions. Bull ejaculates were collected to evaluate seminal quality parameters, sperm membrane integrity, and redox status (SOD; GPx; GSH; GRx; CARB; DCF; and SOD/GPx ratio). Bulls located in the temperate region showed a higher sperm motility rate and percentage of viable sperm (P < 0.05). When evaluating regions independently, we observed a lower GPx activity from animals in the tropical region (P < 0.05). In contrast, we found that SOD and GRx activities, GSH content, and CARB oxidative levels were higher in the tropical region, while oxidation values of DCF were lower (P < 0.05). Braford bulls showed higher CARB and DCF levels (1.23 ± 0.61 nmol/mg and 1453.60 ± 828.63 nmol/mg, respectively) compared to Hereford bulls (1.00 ± 0.43 nmol/mg and 1138.70 ± 423.24 nmol/mg, respectively) in the temperate region. However, Nellore bulls showed higher DCF levels (650.50 ± 401.53 nmol/mg) than Braford bulls (409.40 ± 286.97 nmol/mg). In addition, the SOD/GPx ratio was lower in Braford (12.44 ± 7.64 U/mg) compared to Nellore bulls in tropical conditions (87.25 ± 2.83 U/mg). A positive correlation was found in temperate conditions between DCF levels, SOD, and GRx activities (0.51, 0.58; P < 0.01, respectively), as well as in subtropical conditions between DCF levels and GRx activity (0.53; P < 0.01). A negative correlation between the temperature-humidity index and CARB content was found in subtropical and tropical regions (−0.44; P < 0.01). We concluded that Braford breeds showed lower seminal motility, DCF contents and SOD/GPx ratios compared to Nellore bulls in tropical climate conditions. Finally, in temperate environmental conditions, Braford bulls also showed lower seminal motility but higher levels of CARB and DCF contents compared to Hereford bulls. Therefore, the existence of climatic differences between the temperate and tropical regions evaluated affected Braford bulls’ seminal motility and seminal redox homeostasis.