Charolais Bulls Research Articles

Detectability of multi-dimensional movement and behaviour in cattle using sensor data and machine learning algorithms: Study on a Charolais bull

Detectability of multi-dimensional movement and behaviour in cattle using sensor data and machine learning algorithms: Study on a Charolais bull

Development and validation of a model for early prediction of residual feed intake in beef cattle using plasma biomarkers

Identification of plasma biomarkers for feed efficiency in growing beef cattle offers a promising opportunity for developing prediction models to improve precision feeding strategies. However, these models must accurately predict feed efficiency at early stages of fattening. Our study aimed to evaluate the reliability of candidate biomarkers previously identified in late-fattening cattle when analyzed during early fattening stages and to develop diet-specific prediction equations for residual feed intake (RFI). From a total of 364 Charolais bulls across 7 cohorts, we selected 64 animals with extreme RFI values. The animals were fed either a corn‑ or grass-silage diets. These animals were chosen from 4 out of available 7 cohorts. Animals from three cohorts (24 high-RFI and 24 low-RFI, having a mean RFI difference of 1.48 kg/d) were used for biomarker confirmation and prediction model training. Animals from a fourth cohort (8 high-RFI and 8 low-RFI, having a mean RFI difference of 0.98 kg/d) were used for model external validation. Blood samples were collected at the beginning of the feed efficiency test (333±20 days), and plasma underwent targeted metabolomic for 630 metabolites, natural abundance of 15N (δ15N), insulin, and IGF-1 analysis. Seven previously identified plasma biomarkers for RFI in late-fattening beef cattle still kept their capability for discriminating low and high RFI animals when analyzed during early fattening stages (P < 0.05). Among these confirmed biomarkers, five were common for both grass- and corn-fed animals (creatinine, β-alanine, triglyceride TG18:0_34:2, symmetric dimethyl-arginine and phosphatidylcholine PC aa C30:2) while two were diet-specific (insulin-like growth factor 1 for grass silage-based diet, and isoleucine for corn silage-based diet. No new plasma biomarkers of RFI were identified at early-fattening stages (false discovery rate, FDR>0.05). Prediction models were developed based on seven confirmed RFI biomarkers analyzed during early-fattening. Two logistic regression models incorporating creatinine and either IGF-1 (for grass silage-based diet) or PC aa C30:2 (for corn silage-based diet) effectively distinguished between high and low-RFI animals with high sensitivity and specificity (area under the curve, AUC > 0.80). The biomarkers used in the models showed moderate to high repeatability between early and late fattening stages (45 < r <65). The models were successfully externally validated, with more than 85% of animals from the fourth cohort correctly classified. Once validated in larger cohorts and utilizing cost-effective and rapid analytical methods, these models could support precision feeding and breeding programs, aiming to reduce the cost of raising beef cattle.

Programming and Setting Up the Object Detection Algorithm YOLO to Determine Feeding Activities of Beef Cattle: A Comparison between YOLOv8m and YOLOv10m.

This study highlights the importance of monitoring cattle feeding behavior using the YOLO algorithm for object detection. Videos of six Charolais bulls were recorded on a French farm, and three feeding behaviors (biting, chewing, visiting) were identified and labeled using Roboflow. YOLOv8 and YOLOv10 were compared for their performance in detecting these behaviors. YOLOv10 outperformed YOLOv8 with slightly higher precision, recall, mAP50, and mAP50-95 scores. Although both algorithms demonstrated similar overall accuracy (around 90%), YOLOv8 reached optimal training faster and exhibited less overfitting. Confusion matrices indicated similar patterns of prediction errors for both versions, but YOLOv10 showed better consistency. This study concludes that while both YOLOv8 and YOLOv10 are effective in detecting cattle feeding behaviors, YOLOv10 exhibited superior average performance, learning rate, and speed, making it more suitable for practical field applications.

Unraveling the Complexities of Beef Marination: Effect of Marinating Time, Marination Treatments, and Breed.

The present study focused on evaluating the effects of beef marination on quality traits and consumer acceptability. In this context, m. longissimus thoracis et lumborum and m. semimembranosus samples (n = 192) were obtained from Aberdeen Angus, Hereford, Charolais, and Limousine bulls and were marinated with milk (pasteurized, 100%), garlic and olive oil (2.35 g/500 mL), and lemon (citrus) juice (31% orange juice, 31% lemon juice, 38% distilled water) for 12, 24, and 72 h. Marinade components were selected based on traditional culinary practices and their scientifically proven effects on meat quality. Beef samples on day 0 and non-marinated samples were used as control groups. Beef color, water holding capacity, pH, cooking loss, and Warner-Bratzler shear force were measured three times for each sample. A taste panel assessment was performed to determine the sensory characteristics. Statistical analysis was performed using general linear model (GLM) procedures followed by Tukey's post-hoc comparison. Results revealed that marination time, as well as its two- and three-way interactions, significantly influenced beef quality parameters. These results indicate that the cattle breed is an important factor in evaluating the effectiveness of beef marination applications. The olive oil-garlic marinade was the most preferred by the panel across both types of muscle, as indicated by sensory evaluation results. The findings will not only enrich the scientific literature but also have practical implications for the beef industry.

Dietary protein re-alimentation following restriction improves protein deposition via changing amino acid metabolism and transcriptional profiling of muscle tissue in growing beef bulls

This study aimed to develop a compensatory growth model using growing beef cattle by changing dietary protein and to investigate the underlying mechanisms of compensatory protein deposition in muscle tissue. Twelve Charolais bulls were randomly assigned to one of two groups with two periods: 1) a control group (CON) fed a 13% crude protein (CP) diet for 6 weeks; 2) a treatment group (REC) fed a 7% CP diet for 4 weeks (restriction period) and fed a 13% CP diet in the following 2 weeks (re-alimentation period). Growth performance, digestibility, nitrogen balance, targeted metabolomics of amino acids (AA) in plasma, and transcriptional profiling in muscle tissue were analyzed. Protein restriction decreased average daily gain (ADG; P < 0.05), while protein re-alimentation increased ADG relative to the CON (P < 0.05). Compared to the CON, REC reduced retained N (P < 0.05), and protein re-alimentation increased retained N and N utilization efficiency (P < 0.05), due to reduced urinary urea, hippuric acid, and creatinine excretions (P < 0.05). Ruminal NH3-N in the REC was lower than that in the CON in the protein re-alimentation period (P < 0.05). However, there was no difference in microbial protein and plasma urea nitrogen concentrations. Dietary protein restriction decreased plasma valine and aspartic acid concentrations relative to the CON (P < 0.05), and increased proline and 3-methyl-L-histidine concentrations (P < 0.05). After dietary protein re-alimentation, REC increased plasma citrulline concentrations (P < 0.05). The transcriptional profiling revealed that REC upregulated the AA transporter SLC3A1, and protein re-alimentation downregulated SLC7A8 in the muscle cell membrane. Within the muscle cell, upregulated cytosolic arginine sensor for mTORC1 subunit 2 (CASTOR2) inhibited protein synthesis by inhibiting the mammalian target of rapamycin complex 1 phosphorylation in the protein restriction period, while DNA-damage-inducible transcript 4 (DDIT4) activated the mTOR signaling pathway and promoted protein synthesis in the protein re-alimentation period. In summary, the targeted metabolomics and transcriptomics analyses demonstrated that protein re-alimentation following restriction can promote protein synthesis and reduce muscle breakdown by regulating AA metabolism and functional transcripts related to AA transporters and the mTOR signaling pathway.

Effect of residual feed intake on meat quality in fattening Charolais bulls fed two contrasting diets

The selection of more efficient animals for breeding is of both economic and environmental interest to the industry. The aim of this study was to evaluate the influence of the animals' residual feed intake (RFI) ranking in interaction with the type of diet on the meat quality of Charolais beef cattle. Indeed, several biological mechanisms are associated with RFI, especially when animals are fed high starch-diets. It is therefore possible that quality parameters may show greater changes due to RFI in the context of high starch diets compared to high forage diets.An 84-day feed efficiency trial followed immediately by a second 112-day feed efficiency trial was conducted with a total of 100 animals fed either maize- or grass-diets for 196-days. At the end of the 84-day period, the 32 most divergent RFI animals (16 extreme RFI animals per diet, 8 RFI+ and 8 RFI-) were identified. They were slaughtered after 112-days of finishing. The Longissimus thoracis was characterised in terms of nutritional and sensory quality.RFI had no effect on lab colour, muscle shear force, total fat, fatty acid ratios and most of the total fatty acid content (especially n-3) irrespective of the diet. However, more efficient animals (RFI-) showed higher CLA contents compared to less efficient animals (RFI+) regardless of the diet and also a lower n6/n3 ratio only in animals fed the maize diets. Diet also had a significant effect on lipid and FA content as well as on FA composition.

Modern methods of using industrial crossing, keeping conditions and obtaining additional energy carriers from purebred and crossbred animals

This topic covers a wide range of aspects, including improving the genetic potential of animals through industrial crossbreeding, ensuring optimal housing conditions, and developing technologies for efficient use of the energy generated by these animals. Modern methods of industrial crossbreeding are determined by strategic plans to improve the genetic pool of animals to obtain more productive and disease-resistant offspring. Using advanced genetic technologies and modern breeding methods enhances product quality and ensures resistance to adverse factors. Considering the physiological needs of different breeds, providing appropriate nutrition and maintenance following current standards helps maintain high productivity and ensure the harmonious development of animals. In obtaining additional energy carriers, the latest technologies for using livestock waste in biogas, compost, and other energy resources are being studied. This contributes not only to the improvement of the environmental sustainability of farms but also to the use of internal resources for additional energy production. Summing up, modern approaches to the use of industrial crossing, housing conditions, and obtaining other energy carriers help solve complex tasks in animal husbandry, providing an optimal balance between productivity, efficiency, and environmental sustainability. It was established that the dynamics of live weight gains were more incredible in ½ Charolais steers when kept on deep litter, and on average up to 15 months, the average daily gains amounted to 947.9 g per day, and in purebreds under box keeping – 815.9 g; the absolute gains in live weight of purebred bulls of the Ukrainian black-spotted dairy breed, when kept in boxes for up to 15 months, reached 367.1 kg, which is 16.18 % less than that of ½ Charolais bulls when kept on deep bedding, with a probable difference of Р &lt; 0.001. Innovative approaches to the use of the effect of heterosis and the conditions of keeping overrepair bulls in the production of beef have positive results, where ½ Charolais crossbreeds in conditions of keeping on deep bedding reach 453.9 kg by the age of 15 months, and their purebred counterparts – 406.7 kg, with a probable difference of P &lt; 0.001. The results of the economic efficiency of the use of industrial crossbreeding, keeping conditions of purebred and crossbred bulls, show additional profits per head of 1,468.8 UAH ½ Charolais (maintenance on deep litter) and an increase in the level of profitability by 34.40 % compared to purebred Ukrainian black and white bulls dairy breed (maintenance boxing).

Эффективность производства говядины при чистопородном разведении французских мясных пород скота

Abstract. The purpose is to study the efficiency of beef production from specialized meat breeds of cattle of French origin in comparison with the Hereford breed. Methods. Zootechnical, statistical and economic methods were used. Results. As a result of the conducted scientific and economic experience, the indicators of weight growth and meat productivity of cattle of the Charolais, Salers, Aubrac, Limousin breeds were studied in comparison with the Hereford cattle breed. Scientific novelty consists in the fact that for the first time in the conditions of Western Siberia, a comparative study of the indicators of weight growth from birth to 18 months of age and meat productivity of French beef cattle breeds with the Hereford breed was carried out. The conducted research has established the advantage in live weight and growth intensity of French beef cattle breeds. The largest live weight at 18 months was in Charolais bulls – 569.4 kg, which is more than in group I bulls by 53 kg (10.2 %) (p ≤ 0.001). In second place in terms of live weight were the bulls of the Obrak breed – 552.4 kg, which is significantly more than the peers of group I by 35.7 kg (10.3 %) (p ≤ 0.001. With intensive cultivation, the highest growth energy was demonstrated by bulls of French meat breeds 903.8–966.1. When slaughtered at the age of 15 and 18 months, heavy animal carcasses were obtained. Carcasses of French bull calves at slaughter at 15 months had a larger mass by 10.6–23.5 kg. By 18 months, the mass of paired carcasses increased to 286.6–318.5 kg. Economic analysis of the research results shows that in the production of beef from Charolais cattle, the profitability level is 66.5 %, Hereford breed – 60.6 %, Salers and Aubrac – 62.3, Limousin – 56.4 %.

Gene expression of free fatty acids-sensing G protein-coupled receptors in beef cattle.

Many physiological functions are regulated by free fatty acids (FFA). Recently, the discovery of FFA-specific G protein-coupled receptors (FFARs) has added to the complexity of their actions at the cellular level. The study of FFAR in cattle is still in its earliest stages focusing mainly on dairy cows. In this study, we set out to map the expression of genes encoding FFARs in 6 tissues of beef cattle. We also investigated the potential effect of dietary forage nature on FFAR gene expression. To this end, 16 purebred Charolais bulls were fed a grass silage ration or a maize silage ration (n = 8/group) with a forage/concentrate ratio close to 60:40 for 196 d. The animals were then slaughtered at 485 ± 42 d and liver, spleen, ileum, rectum, perirenal adipose tissue (PRAT), and Longissimus Thoracis muscle were collected. FFAR gene expression was determined by real-time quantitative PCR. Our results showed that of the five FFARs investigated, FFAR1, FFAR2, FFAR3, and GPR84 are expressed (Ct < 30) in all six tissues, whereas FFAR4 was only expressed (Ct < 30) in PRAT, ileum, and rectum. In addition, our results showed that the nature of the forage, i.e., grass silage or maize silage, had no effect on the relative abundance of FFAR in any of the tissues studied (P value > 0.05). Taken together, these results open new perspectives for studying the physiological role of these receptors in beef cattle, particularly in nutrient partitioning during growth.

301 Determining Individual Dry Matter Intake of Charolais Bulls from Ingestion Time Recorded with Rgb-D Cameras

Abstract Monitoring individual dry matter intake (DMI) may help decision-making of cattle producers to improve feed efficiency, health and welfare; however, classic methods to record DMI are expensive and time-consuming (Davison et al., 2021). Thus, since the last years new technologies, such as cameras and Deep Learning (DL) algorithms have been developed to capture individual animal performance in an easier and cheaper way. The aim of this work is to evaluate the capability of an RGB-D camera coupled to a DL algorithm to predict individual DMI of beef cattle. For this, 12 young Charolais bulls (581 ± 37) were recorded during 10 days after meal distribution though an Intel Realsense (TMD455) camera (12 mins per video at 5 frames per second) and their DMI was individually measured. The DL algorithm for video processing was the YOLO (V8). We first trained the model to characterize activity of the animals (biting, chewing, visiting, ruminating and others; Table 1) through manual labelling using 650 images randomly extracted form videos. The images were divided into three sets for training, validation, and testing, (60, 20, and 20%, respectively) and metrics used to evaluate the model were Precision (P), Recall (R) and the average precision (AP). Then, we estimated the ingestion time (IT) by summing predicted biting and chewing time. This predicted IT was compared with the real IT measured through a chronometer. Finally, a mixed effects model was used to predict individual DMI from IT. Results showed an average high precision for all activities predicted (P = 0.62, R = 0.83, AP = 0.81). In addition, activities encompassed on the IT also showed a high precision (AP &amp;gt; 0.84). However, the confusion matrix showed a slight confusion between chewing and visiting (r = 0.14) activities. After processing activity of the animal, we observed a high correlation (r = 0.82, P = 0.001) between predicted and measured IT. Finally, we obtained a significant relationship between DMI and predicted IT (R² = 0.45, P = 0.001, RMSE = ±0.18kg DMI). The present work shows how new technologies such as RGB-D cameras associated to a trained DL algorithm could facilitate data acquisition on cattle farms, which may help decision-making of producers in terms of efficiency, health and welfare of the animal.

41 Growth Performance and Carcass Characteristics of Beef-Sired Steers Born to Holstein Dams

Abstract The objective of this study was to compare feedlot growth performance and carcass characteristics of F1 beef × Holstein steers (n = 124) sired by commercially available Angus (n = 19 from 7 sires), Charolais (n = 79 from 3 sires), SimAngus (n = 16 from 3 sires), or Wagyu (n = 10 from 2 sires) bulls. Male calves born from May to August of 2021, were sourced from 8 Pennsylvania dairy herds. Steers were raised by a commercial calf grower until April of 2021 (10.5 ± 1.5 months of age). Steers were then moved to the PA Department of Agriculture’s Livestock Evaluation Center (LEC) and transitioned to a high-energy ration. Individual feed intake was monitored using the GrowSafe Feed Intake Monitoring System (Model 4000E, Vytelle, Calgary AB, Canada). Steers were slaughtered after 90, 118, or 153 days on feed at the LEC. Pulls were based on a combination of visual appraisal and body weight. Linear models of growth performance traits and carcass characteristics included the fixed effects of sire breed, herd of origin, and birthdate. Binomial models of USDA Quality Grades and Yield Grades included a fixed effect of sire breed. Angus-sired steers were heaviest at feedlot entry (P &amp;lt; 0.01) and were on feed for the fewest days (P &amp;lt; 0.01). Angus × Holstein steers were heavier at slaughter (P &amp;lt; 0.01) than SimAngus and Wagyu-sired steers. Wagyu-sired steers had the least dry matter intake (DMI), average daily gain (ADG), and carcass ADG (P &amp;lt; 0.01) when compared with progeny of other sire breeds. No differences in gain to feed intake (G:F(; P = 0.90), back-calculated carcass G:F (P = 0.62), net energy of metabolism (P = 0.70) and net energy of gain (P = 0.70), nor hip height at harvest (P = 0.14) were detected between sire breeds. Wagyu × Holstein carcasses were the lightest (P &amp;lt; 0.01) and had the least amount of backfat (P = 0.01). Dressing percentage tended to be least (P = 0.10) in Charolais × Holstein carcasses (60.5%) and greatest in SimAngus × Holstein carcasses (61.7%); carcasses from Angus and Wagyu-sired steers were intermediate and not different. About 84% of Angus × Holstein carcasses graded Choice while only 31% of SimAngus × Holstein carcasses graded Choice (P = 0.03). However, there were no differences in called marbling scores between sire breeds (P = 0.15). Charolais × Holstein tended to have the lowest proportion (4%) of Yield Grade 1 carcasses (P = 0.05). Angus-sired steers were on feed for the fewest days when compared with steers sired by other beef breeds. Wagyu × Holstein steers had reduced ADG, DMI, and subsequent carcass weight in comparison with compared steers of other sire breeds.

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.

289 Sperm Quality Assessments Using Flow Cytometry do not Differ between Angus and Charolais Breeds of Yearling Bulls Meeting Breeding Soundness Exam Threshold Requirements

Abstract Flow cytometry has been used as a reliable and objective tool for bull sperm quality assessments and identification of sub-fertility. Our objective was to determine if breed differences exist in sperm quality assessments using flow cytometry when evaluating semen from yearling Angus and Charolais bulls that passed breeding soundness exam (BSE) semen evaluation thresholds. Ejaculates were collected via electroejaculation on one of three consecutive days from yearling (403.15 ± 11.19 d age) Charolais (n=23) and Angus (n=23) bulls as part of a BSE. BSEs were conducted by one veterinarian and all bulls met all requirements as set by the Society for Theriogenology. An additional sperm motility analysis was conducted with the iSperm analyzer. Ejaculates were diluted in BoviFree to 70 million cells/mL and sent overnight for flow cytometry analyses. Sperm flow cytometry analyses included: acrosome and cell membrane integrity, mitochondrial energy potential, and oxidation status. The GLIMMIX procedure of SAS with bull as experimental unit, bull breed as the main effect and collection date as a random variable was used to assess potential differences in sperm quality variables. Neither iSperm (P = 0.26) nor visual assessment (P = 0.66) of sperm motility differed among breeds. Bull breed did not influence (P = 0.83) total percentage of viable cells, nor percentage of viable cells with intact acrosomes (P = 0.83). When evaluating oxidation status by measuring reactive oxygen species, bull breed did not influence (P = 0.92) percentage of live sperm cells with positive reactive oxygen species status. There was a tendency (P = 0.10) for a greater percentage of sperm from Charolais bulls (31.1% ± 3.35) to have positive mitochondrial energy potential as compared with Angus bulls (17.6% ± 3.35). Bull breed appears to have little influence on sperm quality assessments among yearling bulls meeting threshold requirements for passing BSEs.

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.

PSI-5 Comparison of 7&amp;7 Synch and 7-day Co-Synch + Cidr Protocols in a Fixed-Time ai System on Beef Cows Using Y-Sorted sex-Selected Semen

Abstract The 7&amp;7 Synch and the 7-day CO-Synch+CIDR fixed-time estrous synchronization protocols were compared among mature and two-year-old lactating postpartum Angus and SimAngus cows (n=201). Mature (n=63) and two-year-old (n=36) cows treated with the 7&amp;7 Synch received an injection of prostaglandin F2α (PGF; 25 mg dinoprost tromethamine) at the same time as insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) on Day -17, gonadotrophin-releasing hormone (GnRH; 100 μg gonadorelin) on Day -10, and PGF at time of CIDR removal on Day -3. Mature (n=65) and two-year-old (n=37) cows in the 7-day CO-Synch+CIDR groups received an injection of GnRH on Day -10 that coincided with CIDR insertion and received PGF at the time of CIDR removal on Day -3. Fixed-timed AI (FTAI) by a single technician using Y-chromosome-bearing sex-sorted semen (4x106 sperm/unit of SexedULTRA 4M) from one of two Charolais bulls occurred on Day 0, 70 hours after PGF injection. Seven days later bulls were pastured with cows for the remainder of the breeding season. Transrectal ultrasound was performed 77-83 days after AI and fetal size was used to differentiate AI and natural service pregnancies. Within the mature cows and two-year-old age groups, the GLIMMIX procedure in SAS was used to compare FTAI and breeding season pregnancy rates with estrous synchronization treatment and sire as main effects. No differences (P=0.41) were observed amongst mature cows in FTAI pregnancy rates between the 7&amp;7 Synch (52.4%) and the 7-day CO-Synch+CIDR (44.9%) treatments. A greater (P=0.05) proportion of two-year-old cows were pregnant to FTAI following treatment with the 7-day CO-Synch+CIDR (56.7%) as compared to the 7&amp;7 Synch (33.4%). A greater (P=0.02) proportion of two-year-old cows in the 7-day CO-Synch+CIDR treatment (91.9%) were pregnant at the conclusion of the breeding season as compared with the 7&amp;7 Synch (69.7%).

MEAT PRODUCTIVITY OF FRENCH-BRED BULLS DUE TO ADAPTIVE TECHNOLOGY IN WESTERN SIBERIA

The study of meat productivity of introduced cattle breeds in Western Siberia using adaptive technologies is of scientific and practical interest. We carried out the experiment on five cattle groups of Hereford, Limousin, Charolais, Aubrac and Salers bull calves. Furthermore, we determined the indicators of weight growth from birth to 18 months and meat productivity at the age of 18 months. At birth, live weight control was carried out at 3, 6, 9, 12, 15 and 18 months when weighing animals in the morning before feeding and watering. We studied meat productivity during the control slaughter of animals at the Yalutorovsky meat processing plant. Three heads from each group were slaughtered. The slaughter was carried out according to the Lenin All-Union Academy of Agricultural Sciences [VASKhNIL] method. The experimental material was processed by the method of variation statistics using the Microsoft Excel software application. Steers of French meat breeds surpass Hereford cattle breeds in terms of live weight and average daily growth. The carcass weight of Charolais animals is 329.5 kg, which is 75.3 kg more than in Hereford bulls, P≥0.999. The results of the chemical analysis indicate that the highest fat content is contained in the minced meat of Hereford bulls – 10.6%. Introduced cattle breeds, when bred under new conditions, showed a fairly high level of meat productivity, carcasses were obtained during slaughter, with an optimal ratio of tissues and chemical composition of carcasses, in terms of the yield of edible parts in the carcass and the meat content coefficient, they surpass the Hereford cattle breed. Thus, French meat breeds are promising for beef production in Western Siberia.

Individual methane emissions (and other gas flows) are repeatable and their relationships with feed efficiency are similar across two contrasting diets in growing bulls

In the current economic and environmental context, the selection of livestock phenotypes combining high feed efficiency (FE) and low greenhouse gas emissions is interesting. This study aimed to quantify methane (CH4) emissions and other gas flows (carbon dioxide (CO2) and dihydrogen (H2) emissions, oxygen (O2) consumption) in growing bulls fed with two contrasting diets in order to (i) evaluate the persistence of individual variability in gas flows through time, and (ii) assess the inter-individual relationship between gas flows and FE across diets. Charolais bulls were fattened for 6 months during two consecutive years in two independent batches (50–51 per year). In each batch, half of the animals received a total mixed ad libitum ration either based on maize silage (62% dietary DM) or high-starch concentrate (MS-S), and half based on grass silage (59% dietary DM) and high-fibre concentrate (GS-F). The absolute gas flows (g/d) were individually measured with 2 GreenFeed systems during 88 days (group 1) and 64 days (group 2). All gas flows were also expressed in g/kg DM intake (gas yield), in g/kg average daily gain (CH4 intensity) and residual of daily emissions for CH4 (R CH4). Different FE metrics (residual feed intake (RFI), residual gain (RG) and feed conversion efficiency (FCE)) were investigated during the same period. The relationships between gas flows and FE metrics were tested by linear regression with the diet as fixed effect. For both diets, we observed a consistent individual variability over the measurement period for absolutes values (g/d) of CH4, CO2, and O2 (repeatability >0.7 for GS-F and >0.6 for MS-S). Gas flows (g/d) were positively correlated with RFI with both diets: animals that ingested food in excess of their theoretical maintenance and growth requirements emitted more CH4, CO2 and consumed more O2. The positive relationship between absolute CH4 emissions and RFI highlighted the interest for low-CH4 emitters and efficient growing bulls when fed with high-energy diets rich in starch or fibre. For both diets, RCH4, CH4 yield and CH4 intensity were not related to RFI whereas a significant negative relationship was reported between CH4 intensity and RG, and FCE. These data suggest that intake is the main driver of the phenotypic relationships between CH4 traits and RFI. Further studies including larger numbers of animals on highly contrasting energy diets are needed to investigate the underlying biological regulatory mechanisms of the methanogenic potential of an animal in relation to production traits.

Common and diet-specific metabolic pathways underlying residual feed intake in fattening Charolais yearling bulls

Residual feed intake (RFI) is one of the preferred traits for feed efficiency animal breeding. However, RFI measurement is expensive and time-consuming and animal ranking may depend on the nature of the diets. We aimed to explore RFI plasma biomarkers and to unravel the underlying metabolic pathways in yearling bulls fed either a corn-silage diet rich in starch (corn diet) or a grass-silage diet rich in fiber (grass diet). Forty-eight extreme RFI animals (Low-RFI, n = 24, versus High-RFI, n = 24, balanced per diet) were selected from a population of 364 Charolais bulls and their plasma was subjected to a targeted LC-MS metabolomic approach together with classical metabolite and hormonal plasma analyses. Greater lean body mass and nitrogen use efficiency, and lower protein turnover were identified as common mechanisms underlying RFI irrespective of the diet. On the other hand, greater adiposity and plasma concentrations of branched-chain amino acids (BCAA) together with lower insulin sensitivity in High-RFI animals were only observed with corn diet. Conversely, greater plasma concentrations of BCAA and total triglycerides, but similar insulin concentrations were noted in efficient RFI cattle with grass diet. Our data suggest that there are diet-specific mechanisms explaining RFI differences in fattening Charolais yearling bulls.

338 Nitrogen Use Efficiency Is Proportionally More Improved When Young Bulls Are Ranked on Residual Body Gain Rather Than on Residual Feed Intake

Abstract Animals with superior feed efficiency (FE) may also have an improved nitrogen use efficiency (NUE), which would be beneficial to economic profitability while reducing environmental impacts. When genetically selecting animals on FE, it is preferable to use residual traits [e.g. residual feed intake (RFI) or residual body gain (RG)] rather than ratios because of their predictable genetic outcomes. We studied the relationship of RFI and RG with NUE, estimated from the validated 15N abundance in plasma, across two contrasted diets based on corn or grass silages. We evaluated FE of 588 (half by diet) Charolais bulls (545 ± 57 kg BW) from 12 experimental cohorts (different farms and periods) over 200 days. Before the end of the FE test, plasma was sampled and analyzed for δ 15N. NUE was related to FE through simple-linear models with variables previously corrected for the cohort and diet effects. The models’ slopes were standardized according to FE deviation in order to compare the response of NUE to FE between indices. Higher NUE was related to higher FE (P &amp;lt; 0.001), showing positive correlations with RG (r=-0.40) and negative with RFI (r=0.29). However, the standardized slope of NUE to RG was significantly higher (+28%; P &amp;lt; 0.05) than that of NUE to RFI. This stronger NUE relation to RG compared to RFI could reflect a higher potential of RG animals to deposit N as compared to a more conservational N metabolism in RFI individuals. Regarding diets, and despite the correction of NUE and FE for this effect, the slopes of NUE to FE were numerically (P &amp;gt; 0.05) higher (-16% and +36%; for RG and RFI) in corn-based diets, which agrees with superior NUE observed in corn-vs-grass diets. Results suggested that superior RG animals may present proportionally higher NUE than superior RFI animals, with even better results in corn-vs-grass diets.

337 Efficient RFI Bulls Presented Lower Fractional Synthesis Rates of Plasma Proteins When Fed Corn but Not Grass Based Diets

Abstract Protein turnover (PT), the continual synthesis and degradation of body proteins not leading to protein gain, is an essential high energy-demanding process. We assumed that PT might explain the between-animal variations of residual feed intake (RFI). The objective was to measure PT in extreme RFI cattle fed two contrasted diets (grass or corn-based). We conducted a RFI test for 84 days with 100 Charolais bulls and we selected the 32 most extreme (8 per diet and RFI group) for PT measurements using 1) the urinary 3-methyl-histidine to creatinine ratio, as a biomarker of the fractional protein degradation rate (FDR) of skeletal-muscle and 2) the isotopic N turnover rate measured in urine and plasma, as a proxy, respectively, of the whole-body FDR and the fractional protein synthesis rates (FSR) of plasma proteins. The 3-methyl-histidine and creatinine were determined from 10 d total urine collection. Isotopic N turnover in urine and plasma was evaluated by modelling the 15N depletion rate over 112 d following an isotopic N dietary change. Higher plasma FSR and higher skeletal-muscle and whole-body FDR were observed with corn-vs-grass diets (≥11%; P ≤ 0.03), in line with higher metabolizable protein and net energy intakes (≥10%, P = 0.001). Differences between extreme RFI animals were noted with the corn diets only, where efficient animals presented significant lower plasma FSR (-10%; P = 0.04) and numerically lower skeletal-muscle and whole-body FDR (-13% and - 8.9%; P &amp;gt; 0.16 respectively) than non-efficient. Non-significant differences were probably due to an insufficient size of our experimental setup. Plasma FSR is related to the PS of hepatic exportation, hence the lower plasma FSR observed in efficient RFI animals fed corn diets may reflect a lower organs to carcass ratio. Altogether results suggests that efficient RFI bulls fed corn diets had a lower hepatic PT with no-significant changes of whole-body and skeletal muscle PT.