Charolais Heifers Research Articles

Exploring rearing factors to predict potential sensory quality of heifer meat throughout the farm-to-fork continuum

Sensory beef qualities could be impacted throughout the farm-to-fork continuum. The aim of this work was to predict the sensory quality classes of Longissimus muscle established from three sensory descriptors: tenderness, juiciness and flavour intensity. The extreme classes of meat quality were: Q + class including the highest scores for tenderness and juiciness, and an intermediate score for flavour intensity and Q − class including low scores for tenderness, juiciness and flavour intensity. To predict the extreme quality classes, seven decision trees were performed using the individual data related to rearing factors (p = 50), carcase traits (p = 13) and/or aged meat traits (p = 9) of 100 Charolais heifers. The decision trees established from rearing factors and carcass trait data (RF-CARCA-Tree) allowed the highest accuracy of prediction (79.7%) with 90.7% and 66.7% of correctly classified individuals, respectively. Our results showed that different combinations of factors could produce Q + class. Three rearing factors (i.e. the calculated average of concentrates’ net energy content in the diet during the pasture period of pre-weaning period (PWP); the number of days concentrates were offered in calf diet during PWP; and the calculated average of concentrates’ crude protein content in the fattening diet) and the conformation score could be considered as action levers to improve meat quality. These three rearing factors were related to the pre-weaning and fattening periods of the heifer, slowing a possible management of the potential beef quality from rearing factors throughout the life of the heifer. Highlights Beef quality can be improved throughout the heifer’s life by rearing factors related to concentrate in the diet. Sensory beef quality classes could be managed from rearing factors and carcass traits. Raw aged meat data did not allow to improve the prediction of sensory beef quality classes.

Association of postabsorptive glucose and acetate metabolism with feed intake, growth, and efficiency in finishing beef heifers

The objective of this experiment was to determine whether acetate and glucose metabolism and insulin response to glucose are associated with the growth, feed intake, and feed efficiency of finishing heifers. Charolais heifers ( n = 18; initial body weight = 415.7 ± 45.17 kg) were acclimated to restraint with a halter and fed a finishing diet ad libitum using an Insentec feeding system. Following a 12 h fast, a jugular catheter was inserted, and an acetate clearance test was performed followed by a glucose clearance test. Four days after the metabolic tests, heifers began an 84-day DMI and ADG test period. Heifers gained 1.69 ± 0.03 kg/day and consumed 10.4 ± 0.19 kg/day. Acetate and glucose clearance rates were not associated with any production trait ( P ≥ 0.40). Insulin time to peak concentration after the glucose challenge was associated ( r = 0.69; P = 0.003) with G:F, but not peak concentration ( P = 0.45). The increased time to insulin peak could indicate that efficient heifers have pancreatic β-cell dysfunction, which is a contributor to insulin resistance. These data indicate that insulin resistance early in the finishing period could be related to improved feed efficiency in finishing heifers.

223 Impacts of Active Dry Yeast (Saccharomyces cerevisiae) on Gut Permeability in Finishing Beef Cattle

Abstract The objectives of this study were to examine the impacts of active live yeast (Saccharomyces cerevisiae) as a dietary feed additive on dry matter intake, feed sorting, gut permeability, ruminal pH and volatile fatty acids (VFA) concentration, as well as fecal pH and VFA concentration in cattle fed a high-grain finishing diet and subjected to a ruminal acidotic challenge. Fifteen Hereford X Charolais heifers were blocked by BW into three blocks. Heifers were randomly assigned within block to one of two dietary treatments; CON (no additive), or YST (3 g· animal-1· day-1 of active live S. cerevisiae) added to a steam-flaked corn diet (83% steam-flaked corn, 8% wheat straw, 5% soybean meal protein mix, 4% vitamin and minerals on a DM basis). The experimental timeline was as follows: 30 d adaptation (ADPT), 5 d baseline (BASE), 5 d ruminal acidosis challenge (CHAL), and three subsequent 5 d recovery phases (REC1, REC2, and REC3). On day 2 of each phase and days 2 and 4 of CHAL, 179 mM Cr-EDTA and 360 mM Co-EDTA were infused into the omasum and rumen, respectively, as gut permeability markers. Within each phase, in-dwelling pH probes were used to capture reticulo-ruminal pH every 5min for 96 consecutive hours, rumen fluid and fecal grab samples were collected once for every 3 h in a 24 h period, and blood was collected at 2, 4, 12, and 24 h after each Co and Cr infusion. Dry matter intake and feed sorting were measured daily for each animal. Statistical analysis was conducted using PROC GLIMMIX in SAS as a randomized complete block design with block, treatment, and phase as fixed effects and animal as a random effect. Ruminal acidosis was successfully induced using this method, as suggested by the statistically significant reduction in minimum pH and increase in pH range in the CHAL phase compared with other phases of the experiment (P ≤ 0.02). Recovery from the ruminal acidosis challenge was detected within the REC1 phase when comparing minimum pH (CHAL 5.25 vs. REC1 5.54; P = 0.001). Additionally, the sorting behavior of some particle sizes was significantly impacted by phase (P ≤ 0.01). Overall, the addition of yeast to the diet did not impact feed intake, sorting behavior, spot ruminal and fecal pH, volatile fatty acid concentrations in ruminal fluid or feces, or the uptake of Cr-EDTA and Co-EDTA. These results suggest that adding live S. cerevisiae yeast at this dose in a high-grain finishing diet does not impact feed intake, gut permeability, or the production of VFA when ruminal acidosis is induced.

Meat Quality Traits in Beef from Heifers: Effect of including Distiller Grains in Finishing Pasture-Based Diets

Distiller grains (DG), which are the by-product from the bioethanol industry, represent an interesting alternative as animal feedstock. To our knowledge, little information is available on the inclusion of DG on the quality of meat from pasture-fed heifers. Thus, the aim of the present study was to evaluate the effect of DG inclusion in pasture-based systems on the main meat quality attributes of Charolais x Aberdeen Angus heifers. For this purpose, meat from heifers fed with a pasture-based diet without supplementation (P) or with 0.75% of live weight DG supplementation (PDG; DG plus dry-rolled corn, 50:50) or with 0.75% of live weight dry-rolled corn supplementation (PRC) was evaluated. Physical (pH, WHC, color, texture), sensory and nutritional (fat content, fatty acid, and amino acid profile) attributes were evaluated in beef samples. No effect of supplementation was observed on meat pH or color (p > 0.05). Meat from PDG heifers showed higher values of WBSF than meat from P heifers (p = 0.039). However, the overall tenderness evaluated by trained panelists showed no differences due to supplementation (p > 0.05). Our results indicate that the inclusion of DG as a partial corn-replacement supplementation for heifers under grazing represents a strategic tool not only related to meat quality, but also as an alternative to reduce food–feed competition.

A Bos taurus sequencing methods benchmark for assembly, haplotyping, and variant calling

Inspired by the production of reference data sets in the Genome in a Bottle project, we sequenced one Charolais heifer with different technologies: Illumina paired-end, Oxford Nanopore, Pacific Biosciences (HiFi and CLR), 10X Genomics linked-reads, and Hi-C. In order to generate haplotypic assemblies, we also sequenced both parents with short reads. From these data, we built two haplotyped trio high quality reference genomes and a consensus assembly, using up-to-date software packages. The assemblies obtained using PacBio HiFi reaches a size of 3.2 Gb, which is significantly larger than the 2.7 Gb ARS-UCD1.2 reference. The BUSCO score of the consensus assembly reaches a completeness of 95.8%, among highly conserved mammal genes. We also identified 35,866 structural variants larger than 50 base pairs. This assembly is a contribution to the bovine pangenome for the “Charolais” breed. These datasets will prove to be useful resources enabling the community to gain additional insight on sequencing technologies for applications such as SNP, indel or structural variant calling, and de novo assembly.

Genetic relationships among yearling weight, frame score and fertility traits in Charolais heifers

The objective was to estimate heritability, genetic correlations and expected genetic superiority (EGS) by direct selection, and expected correlated genetic superiority of selected sires for yearling weight (YW), frame score (FS), age at first calving (AFC) and heifer fertility (HF) of Mexican Charolais females. Records were provided by the Charolais-Charbray Herd Book de México. Estimates of (co)variance components were estimated applying a four-trait animal model that included direct genetic effect, contemporary group, and the linear and quadratic effect of dam age, except for AFC. Heritability estimates were 0.18, 0.13, 0.15, and 0.13 for YW, FS, AFC and HF, respectively. Genetic correlations (r2) estimates were 0.60, -0.14, 0.14, -0.24, 0.26 and -0.92 for YW-FS, YW-AFC, YW-HF, FS-AFC, FS-HF and AFCHF, respectively. The EGS with 5 and 500 half-sib progeny per sire was 4.72 and 10.58, 0.10 and 0.26, 23.98 and 57.92, and 0.15 and 0.38 for YW, FS, AFC and HF, respectively. The moderate r2 for YW-FS suggests that direct selection to increase YW would increase FS. The strong r2 for AFCHF indicates that direct selection to decrease AFC would improve HF. The low r2 for YW-AFC and YW-HF indicate direct selection for YW would not alter AFC and HF.

Effect of Cymbopogon citratus on Enteric Methane Emission, Nutrients Digestibility, and Energy Partition in Growing Beef Cattle

Methane production is a waste of energy for ruminants and contributes to greenhouse gas emissions. The objective of the present study was to evaluate the anti-methanogenic effect of increasing the supplementation levels of Cymbopogon citratus (CC) on the dry matter intake (DMI), digestibility, methane (CH4) production, and partitioning of the gross energy intake in growing beef heifers fed with a diet high in forage (68.6% forage: 31.4% concentrate). An experiment was conducted using Holstein × Charolais heifers distributed in a 4 × 4 Latin square design. The experimental treatments were: (1) control diet (CO), (2) CO + 30 g CC DM/d, (3) CO + 60 g CC DM/d CC, and (4) CO + 90 g CC DM/d. A reduction of 22.4% in methane yield (CH4 g/kg DMI) and a reduction of 21.2% in the Ym factor was observed with the 30 CC treatment (p ≤ 0.05). However, no significant differences (p > 0.05) were observed for the total daily CH4 production, DMI, nutrient digestibility, and gross energy intake partitioning in the heifers. Therefore, we concluded that the supplementation of 30 g CC DM/d reduced the CH4 yield without affecting the animal performance. However, the anti-methanogenic properties of Cymbopogon citratus deserve more investigation.

Untargeted metabolomics confirms the association between plasma branched chain amino acids and residual feed intake in beef heifers.

This study explored plasma biomarkers and metabolic pathways underlying feed efficiency measured as residual feed intake (RFI) in Charolais heifers. A total of 48 RFI extreme individuals (High-RFI, n = 24; Low-RFI, n = 24) were selected from a population of 142 heifers for classical plasma metabolite and hormone quantification and plasma metabolomic profiling through untargeted LC-MS. Most efficient heifers (Low-RFI) had greater (P = 0.03) plasma concentrations of IGF-1 and tended to have (P = 0.06) a lower back fat depth compared to least efficient heifers. However, no changes were noted (P ≥ 0.10) for plasma concentrations of glucose, insulin, non-esterified fatty acids, β-hydroxybutyrate and urea. The plasma metabolomic dataset comprised 3,457 ions with none significantly differing between RFI classes after false discovery rate correction (FDR > 0.10). Among the 101 ions having a raw P < 0.05 for the RFI effect, 13 were putatively annotated by using internal databases and 6 compounds were further confirmed with standards. Metabolic pathway analysis from these 6 confirmed compounds revealed that the branched chain amino acid metabolism was significantly (FDR < 0.05) impacted by the RFI classes. Our results confirmed for the first time in beef heifers previous findings obtained in male beef cattle and pointing to changes in branched-chain amino acids metabolism along with that of body composition as biological mechanisms related to RFI. Further studies are warranted to ascertain whether there is a cause-and-effect relationship between these mechanisms and RFI.

Characterization of Three Different Mediterranean Beef Fattening Systems: Performance, Behavior, and Carcass and Meat Quality.

Simple SummaryBeef fattening systems present a large diversity according to the effect of the type (genetics and gender) of animals fattened, the nutrition programs, the housing conditions, and days on feed, resulting in different carcass traits and meat qualities. New beef fattening systems are arising in Mediterranean countries raising crossbred Angus bulls seeking new marketing opportunities. One of the strengths of the present study is that all animals of the three compared different production systems, two conventional (crossbred heifers, Holstein bulls) and one innovative (crossbred Angus bulls), were raised following their own commercial program (days on feed, nutrition) under the same housing, care, and weather conditions. Furthermore, the carcass and meat quality parameters were analyzed by using a common methodology. With this experimental design, potential factors like the housing conditions or the methodology used to analyze carcass and meat quality (aging time, cooling temperatures, lab equipment) did not interfere in data interpretation. The results indicated that fattening crossbred Angus bulls is suitable in an intensive fattening program but technical data (performance, meat quality or consumer preferences) do not support it as a better alternative to the current Holstein bull production.The aim of this study was to characterize three different commercial dairy beef fattening systems for intensive Mediterranean fattening programs differing in gender, breed, nutrition, and days of feed in order to describe their performance, behavior, and carcass and meat quality when they were raised simultaneously under the same housing and care conditions. Treatments were three different production systems: (1) crossbred Holstein x beef breeds such as Charolais or Limousine heifers, slaughtered at 10 months of age (CBH10, n = 41); (2) Holstein bulls, slaughtered at 11 months of age (HB11, n = 42); and (3) crossbred Holstein x Angus bulls, slaughtered at 12 months of age (CAB12, n = 37). According to our results, moving from a production system based on Holstein bulls to the crossbred Angus production system has no technical support as no large production and meat quality improvements were observed, and only marketing strategies for meat differentiation and consumer trends could favor this decision.

Characterization of Four Rearing Managements and Their Influence on Carcass and Meat Qualities in Charolais Heifers.

The study aim was to identify the effects of the rearing management applied throughout the heifers’ life on the carcass (e.g., conformation, marbling, fat) and meat (color, texture, and sensory profiles) properties. From the individual data of 171 heifers from 25 commercial farms, a typology of four rearing managements was established from 50 rearing factors. The managements had an effect on the conformation, the color (fat and muscle), and the rhomboideus grain meat, for the carcass, and the lightness, the atypical flavor, and the overall acceptability for the longissimus (LM) meat. The carcass traits compared to the meat were more sensitive to a change of rearing management. Our results confirmed that it was possible to target the same carcass or meat quality from different managements. Moreover, according to the aims of the targeted carcass and LM meat quality, management 3 could be an interesting trade-off to jointly manage the quality of both products. For example, the carcasses that were produced had a high conformation, smooth meat grain and the LM meat was more liked. This management was intermediate compared to the other rearing managements and had a long fattening period with a diet mainly based on conserved grass and a high concentrate quantity.

Effect of a High Welfare Floor and a Concrete Slatted Floor on the Growth Performance, Behavior and Cleanliness of Charolais and Limousin Heifers: A Case Study.

Simple SummaryThe barn floor needs to provide a confident and comfortable walking surface while retaining durability and affordability. The floor of the barn is also important in order to achieve the best performance, health and welfare of the animals. Therefore, we compared a high welfare floor (HWF), which should offer higher comfort, to a concrete slatted floor (CSF), which is a standard housing system for cattle rearing. In the trials, Charolais and Limousin heifers were used testing the latter systems. We observed that heifers housed on an HWF tended to exhibit more species-specific behaviors, namely rubbing, grooming and aggression, and seemed to be cleaner than those housed on a CSF.Various floor systems are used in cattle housing with different characteristics in terms of roughness, abrasion, wetness, bedding material, ease of cleaning, etc. Thus, the activity and welfare of the animals are greatly influenced by the type of floor. The floor of the barn can influence the development of health diseases, technopathies and the production and quality of animal products. Therefore, in the present case study, we studied the effects of two different flooring systems on the performance and on some behavioral and cleanliness parameters in heifers. Two floor systems (concrete slatted flooring (CSF) and high welfare flooring (HWF)) and two breeds (Charolais and Limousin) were used in the experiment. Heifers on HWF tended to show a higher frequency of grooming, rubbing and aggression than those on CSF, but not of standing, lying, eating, drinking, rumination, resting, stereotypies and covering of the animals. In addition, animals housed on HWF also appeared to show higher cleanliness than those housed on CSF. Results indicated that animals housed on HWF exhibited more social and self-care behaviors, suggesting that animals housed on such floors show more species-specific behaviors and have higher welfare.

PSVII-18 Association of post-absorptive glucose and acetate metabolism with feed intake, growth, and efficiency in finishing beef heifers

Abstract Glucose and acetate are important nutrients for muscle and fat accretion in beef cattle. The objective of this experiment was to determine if the demand for acetate and glucose, as well as insulin response to glucose, are associated with dry matter intake (DMI), average daily gain (ADG), residual feed intake (RFI), and gain:feed (G:F). Charolais heifers (n = 16; initial BW = 412 ± 10 kg) were trained to close human contact and fed a finishing diet ad libitum in an Insentec feeding system. Following a 12-hour fast, a jugular catheter was inserted, and an acetate clearance test was performed by infusing acetate (2.18 mmol/kg BW0.75) and collecting blood samples over a 30-minute period. One hour after the conclusion of the acetate test, a glucose clearance test was performed by infusing glucose (7.57 mmol/kg BW0.75) and collecting samples over a two-hour period. Four days after the metabolic tests, heifers began an 84-d DMI and ADG test period. The area under the acetate, glucose, and insulin curves were calculated as were the clearance rate, peaks, nadir, and insulin time to peak. Pearson correlations were calculated for the metabolic parameters and production traits using SAS 9.4. Heifers gained 1.69 ± 0.03 kg/d and consumed 10.4 ± 0.19 kg/d. Acetate and glucose clearance rates were not associated with any production trait (P &amp;gt; 0.40). Insulin time to peak concentration after the glucose challenge was associated (r = 0.69; P = 0.003) with G:F, but peak concentration was not (P = 0.45). Additionally, there was a trend (r = 0.40; P = 0.13) for area under the insulin curve to be associated with G:F. Given the small sample size in this experiment, it is possible that decreased insulin sensitivity early in the finishing period is related to improved feed efficiency in finishing heifers.

Kohonen Artificial Neural Network and Multivariate Analysis in the Identification of Proteome Changes during Early and Long Aging of Bovine Longissimus dorsi Muscle Using SWATH Mass Spectrometry.

To study proteomic changes involved in tenderization of Longissimus dorsi, Charolais heifers and bulls muscles were sampled after early and long aging (12 or 26 days). Sensory evaluation and instrumental tenderness measurement were performed. Proteins were analyzed by gel-free proteomics. By pattern recognition (principal component analysis and Kohonen’s self-organizing maps) and classification (partial least squares-discriminant analysis) tools, 58 and 86 dysregulated proteins were detected after 12 and 26 days of aging, respectively. Tenderness was positively correlated mainly with metabolic enzymes (PYGM, PGAM2, TPI1, PGK1, and PFKM) and negatively with keratins. Downregulation in hemoglobin subunits and carbonic anhydrase 3 levels was relevant after 12 days of aging, while mimecan and collagen chains levels were reduced after 26 days of aging. Bioinformatics indicated that aging involves a prevalence of metabolic pathways after late and long periods. These findings provide a deeper understanding of changes involved in aging of beef and indicate a powerful method for future proteomics studies.

Meloxicam administration in the management of postoperative pain and inflammation associated with caesarean section in beef heifers: Evaluation of reproductive parameters

Post-operative pain and inflammation are normal physiological reactions to caesarean section. Their management in cattle have rarely been investigated. This surgical procedure negatively affects reproductive function with, for example, a reduction in fertility resulting in an increase in calving interval. In this multicenter clinical trial, the objective was to evaluate the impact on reproductive performance of meloxicam injected before caesarean section to manage post-operative pain and inflammation. Meloxicam is a non-steroidal anti-inflammatory drug. One hundred and twenty-seven Charolais heifers (n = 127) were recruited from 47 farms in six French veterinary practices in the Burgundy region. The heifers underwent a non-elective standardized caesarean section operation. Heifers were randomly assigned to one of two groups: meloxicam (n = 66), intravenous meloxicam injection before surgery, or control (n = 61). Reproductive performance and health information were recorded from the time of the caesarean section to the next calving or to culling. In our study, meloxicam administration before caesarean section had no effect on the incidence of retained placenta (18.2% of treated vs 25.0% of control cows, p = 0.35). The pregnancy rate was higher in treated than in control cows (83.1% vs 67.8%, p = 0.04 after multivariate analysis) and a survival analysis showed that the median calving interval was 35 days shorter in the meloxicam (t50% = 417 days) compared to the control group (t50% = 452 days, p = 0.05). A trend was also observed for culling rate to be lower in treated (4.7%) compared to control cows (13.3%, p = 0.09). In conclusion, this study suggests that there is a beneficial effect of meloxicam administration before caesarean section on reproductive performance in Charolais heifers.

Short communication: Reference intervals for claw dimensions of intensively finished Charolais and Limousin young bulls and heifers housed on different flooring systems

This study aimed at calculating reference intervals for specific claws dimensions of healthy feet originating from intensively finished Charolais (CH) and Limousin (LIM) young bulls and heifers. Moreover, within a given breed × gender combination, measurements of healthy and affected claws were compared to investigate how claw conformation might change in relation to the housing on different types of floor. A total of 2237 CH feet (1324 bulls; 913 heifers) and 595 LIM feet (459 bulls; 136 heifers) were analyzed post-mortem during 20 sessions in three slaughterhouses in Northern Italy. Four measurements were performed on lateral claws of each hind foot: dorsal wall (DW) and total hoof (TH) lengths, heel height (HH) and toe angle (TA). Afterwards, a veterinarian trimmed the sole horn and assessed claw health condition by looking for specific disorders. A foot with no claw disorder was classified as -“healthy”, whereas when at least one claw disorder of different etiology was observed, the foot was classified as “affected”. A reduced dataset considering only healthy feet was used to calculate 95% reference intervals (RI) for each claw dimension according to breed (CH/LIM) × gender (bulls/heifers) combination. Relevant batch variance was detected for DW, TH and HH of CH heifers and for DW and TH of LIM heifers. These calculated RI might be used to assess claw condition and its predisposition to diseases in finishing beef cattle belonging to the tested beef categories. Affected claws belonging to both CH young bulls and heifers showed greater HH than healthy claws. In presence of claw disorders, CH young bulls and heifers housed on deep litter had longer DW and TH lengths, but only heifers showed shorter TA compared to healthy ones. Longer claws and higher heels of CH should be carefully monitored as indirect indicators of the presence of some disorders, particularly when housed on less-wearing surfaces. Claw health condition had no effect on conformation in LIM young bulls or heifers housed on different types of floor. The housing of young bulls, regardless of breed, on concrete slatted floor showed the highest occurrence of feet affected by any claw disorders, confirming the harmfulness of this type of floor for finishing beef cattle.

Methane and Carbon Dioxide Emission of Beef Heifers in Relation with Growth and Feed Efficiency.

Simple SummaryFor sustainable meat production, beef farmers must make the best use of grass and roughage while limiting the carbon footprint of their herds. The genetic improvement in feed efficiency and enteric methane production of replacement heifers is possible if the recorded phenotypes are available. Intuitively, the relationship between the two traits should be negative, i.e., favorable, since the energy lost with the methane is not available for heifer metabolism. The measurement of feed efficiency requires several weeks of feed intake recording. The enteric methane emission rate can also be recorded over several weeks. The two traits of 326 beef heifers from two experimental farms were measured simultaneously for 8 to 12 weeks. The correlations between roughage intake, daily gain, and methane were all positive. The enteric methane emission rate was positively related to body weight, daily gain, and dry matter intake. The relationship with feed efficiency was slightly positive, i.e., unfavorable. Therefore, the two traits should be recorded simultaneously to evidence low-emitting and efficient heifers. This study also showed that replacing the feed intake recording with the carbon dioxide emission rate appeared potentially beneficial for selecting these low-emitting and efficient heifers.Reducing enteric methane production and improving the feed efficiency of heifers on roughage diets are important selection objectives for sustainable beef production. The objective of the current study was to assess the relationship between different methane production and feed efficiency criteria of beef heifers fed ad libitum roughage diets. A total of 326 Charolais heifers aged 22 months were controlled in two farms and fed either a grass silage (n = 252) or a natural meadow hay (n = 74) diet. Methane (CH4) and carbon dioxide (CO2) emission rates (g/day) were measured with GreenFeed systems. The dry matter intake (DMI), average daily gain (ADG), CH4 and CO2 were measured over 8 to 12 weeks. Positive correlations were observed among body weight, DMI, ADG, CH4 and CO2. The residual feed intake (rwgDMI) was not related to CH4 or residual methane (rwiCH4). It was negatively correlated with methane yield (CH4/DMI): Rp = −0.87 and −0.83. Residual gain (rwiADG) and ADG/DMI were weakly and positively related to residual methane (rwiCH4): Rp = 0.21 on average. The ratio ADG/CO2 appeared to be a useful proxy of ADG/DMI (Rp = 0.64 and 0.97) and CH4/CO2 a proxy of methane yield (Rp = 0.24 and 0.33) for selecting low-emitting and efficient heifers.

Risk factors for claw disorders in intensively finished Charolais beef cattle

This cross-sectional study aimed at performing a risk factor analysis of on-farm housing and management factors associated with infectious and non-infectious claw disorders of intensively finished Charolais young bulls and heifers. Claws’ health condition of a total of 1305 animals belonging to 88 batches finished in farms located in the Eastern Po Valley (Italy) was assessed at slaughterhouse. Batch prevalence of feet affected by sole hemorrhage (SH) and white line abscess (WLA) was calculated and foot condition was summarized by infectious lesion (ILS) and non-infectious lesion (NILS) scores according to diseases’ etiology. Batch prevalence of feet with SH, WLA, and assigned to the worst score classes were the outcomes in the risk factor analysis. Information about rearing facilities and health management of the tested batches were gathered in each origin farm along with a dietary sample used for chemical and physical analyses. Five categorized factors and 30 continuous covariates were considered as independent predictors and a cluster analysis of the continuous covariates was performed to select the most representative ones. Percentage of feet/batch affected by SH was on average 57.0 ± 32.5 % (SD) and by WLA was 9.94 ± 12.7 %. Percentage of feet/batch with the worst ILS and NILS was 29.6 ± 32.8 % and 12.5 ± 14.1 %, respectively. Charolais bulls showed a higher risk of SH and WLA than heifers and an increasing dietary NDF content acted as preventive factor. Concrete slats increased the risk of SH. Animals slaughtered in winter had the highest risk of WLA and the increasing level of dietary water-soluble carbohydrates (WSC) was a further risk factor. The risk for the worst NILS was lowest in spring and in presence of ventilation systems. It increased for bulls and in those batches fed diets with higher WSC content. Batches for which the farmer reported a higher prevalence of urgently slaughtered animals during finishing showed a higher risk of WLA and infectious claw diseases. The risk for infectious claw diseases was reduced in animals slaughtered in summer, housed on deep litter and fed diet with increased NDF content. It increased in farms where diet formulation was not under the nutritionist control. As general outcomes of the study, benefits for the claw health of finishing Charolaise may come from the use of the deep litter and ventilation systems, the involvement of a nutritionist in diet formulation, and the provision of diets with reduced WSC and increased NDF contents.

Tsukishima Kikai Co Ltd, Japan

In practice cattle may be slaughtered at different combinations of age and weight. As each of these factors could affect meat quality traits, the present work aimed to identify which combination can be expected to increase overall meat quality of m. rectus abdominis of Charolais heifers. Totally, 40 heifers were slaughtered either at 26±1 or at 36±1 months of age. Young heifers were sampled at two different carcass weights (349±12 and 394±8 kg). Old heifers were also sampled at two different carcass weights (397±6 and 451±9 kg). The m. rectus abdominis was excised 24 h postmortem to determine metabolic enzyme activities, myosin heavy-chain isoform proportions, lipid contents, collagen content and collagen solubility. Shear force measurements were evaluated on raw and broiled meat after 14 days of ageing. Meat quality traits scored between 0 and 10 by sensory analysis. Increasing slaughter age from 26 to 36 months had no impact on either raw/broiled shear force (0.31⩽P⩽0.47) and/or meat quality traits (0.62⩽P⩽0.91) or on physicochemical properties of heifer’s meat samples. Increasing carcass weight for a similar slaughter age of 26 months had also impact neither on meat quality traits (0.52⩽P⩽0.91) nor on muscular properties. On the contrary, increasing carcass weight for a similar slaughter age of 36 months had induced a decrease of muscular shear force (raw muscle; P=0.009) and a concomitant decrease of total collagen content (P=0.03). Nevertheless, no significant impact on meat quality traits was revealed by the sensorial panel (0.13⩽P⩽0.49). Metabolic enzyme activities (0.13⩽P⩽0.86) and myosin heavy-chain proportions (0.13⩽P⩽0.96) were not significantly impacted by slaughter age and carcass weight. Thus, the impact of increasing carcass weight and/or slaughter age in young Charolais heifers has a limited impact on meat quality traits and associated muscular characteristics. Modulating heifer’s cycles (age and/or carcass weight in the studied range) appears to be a way to answer to the numerous marketing chains, without penalising meat quality traits.

Effect of age and carcass weight on quality traits of m. rectus abdominis from Charolais heifers

In practice cattle may be slaughtered at different combinations of age and weight. As each of these factors could affect meat quality traits, the present work aimed to identify which combination can be expected to increase overall meat quality of m. rectus abdominis of Charolais heifers. Totally, 40 heifers were slaughtered either at 26±1 or at 36±1 months of age. Young heifers were sampled at two different carcass weights (349±12 and 394±8 kg). Old heifers were also sampled at two different carcass weights (397±6 and 451±9 kg). The m. rectus abdominis was excised 24 h postmortem to determine metabolic enzyme activities, myosin heavy-chain isoform proportions, lipid contents, collagen content and collagen solubility. Shear force measurements were evaluated on raw and broiled meat after 14 days of ageing. Meat quality traits scored between 0 and 10 by sensory analysis. Increasing slaughter age from 26 to 36 months had no impact on either raw/broiled shear force (0.31⩽P⩽0.47) and/or meat quality traits (0.62⩽P⩽0.91) or on physicochemical properties of heifer’s meat samples. Increasing carcass weight for a similar slaughter age of 26 months had also impact neither on meat quality traits (0.52⩽P⩽0.91) nor on muscular properties. On the contrary, increasing carcass weight for a similar slaughter age of 36 months had induced a decrease of muscular shear force (raw muscle; P=0.009) and a concomitant decrease of total collagen content (P=0.03). Nevertheless, no significant impact on meat quality traits was revealed by the sensorial panel (0.13⩽P⩽0.49). Metabolic enzyme activities (0.13⩽P⩽0.86) and myosin heavy-chain proportions (0.13⩽P⩽0.96) were not significantly impacted by slaughter age and carcass weight. Thus, the impact of increasing carcass weight and/or slaughter age in young Charolais heifers has a limited impact on meat quality traits and associated muscular characteristics. Modulating heifer’s cycles (age and/or carcass weight in the studied range) appears to be a way to answer to the numerous marketing chains, without penalising meat quality traits.

Characterizing Feedlot Heifer Response to Environmental Temperature

<abstract> <b><sc>Abstract.</sc></b> It has been shown that feedlot cattle vary in their response to environmental temperature. There is a need to develop a parameter to summarize those varied responses, i.e., a heat stress phenotype. The goal of this investigation is to quantify animal response to environment by describing each animal with a parameter and to investigate how this parameter is impacted by management practices. Responsiveness was determined to be a useful parameter to describe the impact of dry-bulb temperature (t_db) on respiration rate (RR) of feedlot heifers. Responsiveness was defined as the slope of RR to t_db. It is a valid and useful parameter because it expresses a single value for each animal that includes the dynamic interaction of RR and t_db. Using the responsiveness parameter, it was determined that unshaded feedlot cattle had a lower responsiveness than shaded cattle. It was noted that there were a range of responsiveness values for all colors of cattle tested; thus, it is likely that there is genetic variation in this parameter. This parameter may prove useful for genomic analysis of heat stress. In shaded animals, the effects of color were minimized. Therefore, dark breeds and composite breeds (Angus and dark red MARC III composite) showed more of a reduction in responsiveness than tan-colored MARC I composites, while Charolais heifers showed no response to shade. While responsiveness was shown to be a useful parameter, it may not be optimal, and other candidate parameters need to be explored.