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This publication discusses certified beef programs and carcass quality specifications. Written by Tracy Scheffler, Jason Scheffler, and Chad Carr, and published by the UF/IFAS Department of Animal Sciences, October 2021.

Postnatal muscle growth is accompanied by increases in fast fiber type compositions and hypertrophy, raising the possibility that a slow to fast transition may be partially requisite for increases in muscle mass. To test this hypothesis, we ablated the

This publication provides information for Florida residents who want to sell meat and poultry from their own livestock and poultry. Written by Chad Carr, Jason Scheffler, and Matthew Johansson, and published by the UF/IFAS Department of Animal Sciences, revised August 2021.

Animal Science (ANS) programs have seen the demographics of their students progressively shift to include more urban and suburban students with limited firsthand knowledge of production agriculture. A major contributor to that shift is an influx of students with the intent of pursuing veterinary school, primarily with the goal of working with companion animals. The change in students has its challenges, but also presents opportunities. It is a chance to communicate with our customers, voters, and prospective thought leaders and decision makers. It is also a chance to recruit new and diverse talent into animal agriculture to help solve current and future problems. Despite the high number of students interested in pursuing vet school, a small percentage gain admittance making it important to help students recognize alternate career paths as soon as possible. This is particularly critical at the University of Florida where 41% of our students are transfers. We questioned if the students’ focus on entering the veterinary field is due to viewing it as their best career opportunity, or their only opportunity. We conducted a career awareness survey at the start and end of the ANS3006 Introduction to Animal Science course over the past several years. Over 49% could not list more than two ANS-related careers. Veterinarian was the most common and appeared on 76% of responses. In turn, we have incorporated more career-related content into ANS3006. In the post survey evaluation, 57% listed more than two careers and 18.8% of students indicated their career goals had changed over the course of the semester, with more than 2/3 of those being students who changed from a veterinary path. Anecdotally, our advisors report students are more amenable to changing from the pre-vet track when encouraged. Emphasizing the opportunities is an effective way to help students find the career paths they may have otherwise missed.

To continue the series that began in 1994, the National Beef Quality Audit (NBQA) – 2016 was conducted to quantify the quality status of the market cow and bull beef sector, as well as determine improvements made in the beef and dairy industry since 2007. The NBQA-2016 was conducted from March through December of 2016, and assessed hide-on carcasses (n = 5,278), chilled carcasses (n = 4,285), heads (n = 5,720), and offal items (n = 4,800) in 18 commercial processing facilities throughout the United States. Beef cattle were predominantly black-hided; 68.0% of beef cows and 67.2% of beef bulls possessed a black hide. Holstein was the predominant type of dairy animal observed. Just over half (56.0%) of the cattle surveyed had no mud contamination on the hide, and when mud was present, 34.1% of cattle only had small amounts. Harvest floor assessments found 44.6% of livers, 23.1% of lungs, 22.3% of hearts, 20.0% of viscera, 8.2% of heads, and 5.9% of tongues were condemned. Liver condemnations were most frequently due to abscess presence. In contrast, contamination was the primary reason for condemnation of all other offal items. Of the cow carcasses surveyed, 17.4% carried a fetus at the time of harvest. As expected, mean carcass weight and loin muscle area values observed for bulls were heavier and larger than cows. The marbling scores represented by cull animal carcasses were most frequently slight and traces amounts. Cow carcasses manifested a greater amount of marbling on average than bull carcasses. The predominant fat color score showed all carcasses surveyed had some level of yellow fat. Only 1.3% of carcasses exhibited signs of arthritic joints. Results of the NBQA-2016 indicate there are areas in which the beef and dairy industries have improved and areas that still need attention to prevent value loss in market cows and bulls.

A disproportionate number of Animal Science (ANS) students start their program with the intent of pursuing veterinary school. While some succeed, most change career paths either by personal choice or not gaining admission into veterinary school. Ideally, the sooner a student identifies alternative career path(s), the more opportunities they have to prepare for those careers by pursuing additional classes and extracurriculars. The University of Florida (UF) is unique compared to peer institutions with a 30% freshman acceptance rate, an overwhelming 41% of UF ANS students arrive as transfers. This compresses the time to matriculate through the ANS curriculum and increases the urgency to redirect students into the numerous ANS career paths. The objective of this study is to better understand ANS student’s perceptions of careers. We conducted a career awareness survey at the start and end of the ANS3006 Introduction to Animal Science course over the past two years. Students (n=352) were asked demographic information, and completed an online instrument evaluating their awareness of career options available to them. Over 49% could not list more than two careers. Veterinarian was the most common and appeared on 76% of responses. Students are exposed to careers throughout each lecture module and related career-focused assignments. In the post test evaluation, 57% listed more than two careers, with the average increasing from 2.8 to 3.6 careers per student. Additionally, 18.8% of students indicated their career goals had changed over the course of the semester, with more than 2/3 or those being students who changed from a veterinary path. In conclusion, ANS students arriving at UF have a limited outlook on career options. While introduction to ANS has some success in expanding those options, more efforts need to be made in the current curriculum and through secondary education to increase awareness of ANS careers.

The National Beef Quality Audit–2016 marks the fourth iteration in a series assessing the quality of live beef and dairy cows and bulls and their carcass counterparts. The objective was to determine the incidence of producer-related defects, and report cattle and carcass traits associated with producer management. Conducted from March through December of 2016, trailers (n = 154), live animals (n = 5,470), hide-on carcasses (n = 5,278), and hide-off hot carcasses (n = 5,510) were surveyed in 18 commercial packing facilities throughout the United States. Cattle were allowed 2.3 m2 of trailer space on average during transit indicating some haulers are adhering to industry handling guidelines for trailer space requirements. Of the mixed gender loads arriving at processing facilities, cows and bulls were not segregated on 64.4% of the trailers surveyed. When assessed for mobility, the greatest majority of cattle surveyed were sound. Since the inception of the quality audit series, beef cows have shown substantial improvements in muscle. Today over 90.0% of dairy cows are too light muscled. The mean body condition score for beef animals was 4.7 and for dairy cows and bulls was 2.6 and 3.3, respectively. Dairy cattle were lighter muscled, yet fatter than the dairy cattle surveyed in 2007. Of cattle surveyed, most did not have horns, nor any visible live animal defects. Unbranded hides were observed on 77.3% of cattle. Carcass bruising was seen on 64.1% of cow carcasses and 42.9% of bull carcasses. However, over half of all bruises were identified to only be minor in severity. Nearly all cattle (98.4%) were free of visible injection-site lesions. Current results suggest improvements have been made in cattle and meat quality in the cow and bull sector. Furthermore, the results provide guidance for continued educational and research efforts for improving market cow and bull beef quality.

The objectives of this study were to estimate variance components, genetic parameters, EBV, accuracies, and rankings for nine ultrasound and carcass traits in a multibreed Angus-Brahman population using three genomic-polygenic models and one polygenic model (PM). The genomic-polygenic models used the complete GeneSeek GPF250k SNP set (GPM), top 5% SNP (GPMR1), and 5% SNP evenly spread across the genome (GPMR2). Yearling ultrasound traits were weight (UW), ribeye area (UREA), backfat (UFAT), and percent intramuscular fat (UPIMF). Carcass traits were slaughter age (SLA), hot carcass weight (HCW), ribeye area (REA), backfat thickness (FAT), and marbling score (MAR). The 9-trait GPM, GPMR1, GPMR2, and PM contained fixed contemporary group, age of calf (ultrasound traits only), sex of calf, and direct heterosis effects, and random animal and residual effects. Variance components and genetic parameters were computed using AIREMLF90. Comparable heritabilities were obtained with GPM and PM for UW (GPM: 0.54 ± 0.05; PM: 0.51 ± 0.05), UREA (GPM: 0.36 ± 0.03; PM: 0.34 ± 0.03), UFAT (GPM: 0.12 ± 0.02; PM: 0.11 ± 0.02), UMPIMF (GPM: 0.34 ± 0.03; PM: 0.30 ± 0.03), SLA (GPM: 0.59 ± 0.07, PM: 0.61 ± 0.06), HCW (GPM: 0.58 ± 0.06, PM: 0.52 ± 0.07), REA (GPM: 0.48 ± 0.04, PM: 0.45 ± 0.05), FAT (GPM: 0.41 ± 0.05, PM: 0.30 ± 0.05), and MAR (GPM: 0.56 ± 0.07, PM: 0.51 ± 0.08). Additive genetic correlations between pairs of ultrasound and carcass traits were all between −0.31 and 0.81. The highest positive additive genetic correlations were between UW and UREA, UW and HCW, UW and REA, UREA and HCW, UREA and REA, UFAT and FAT, and between HCW and REA. The largest negative additive genetic correlations were between UREA and UPIMF, UFAT and SLA, UFAT and HCW, UPIMF and REA, and between REA and MAR. High similarity existed among predicted EBV and accuracies from GPM, GPMR1, and GPMR2 as well as high-rank correlations for sires, dams, and progenies. This indicated that the two reduced genotype sets were appropriate alternatives to the complete GPF250k set for genomic-polygenic evaluation and selection in this multibreed Angus-Brahman population. High EBV variability existed among animals of all Angus and Brahman percentages and no specific breed composition was overwhelmingly better or worse for any of the nine traits. This indicated that optimization of genetic progress through selection in multibreed Angus-Brahman populations should be based solely on genetic merit regardless of breed composition.

The National Beef Quality Audit (NBQA)-2016 used in-plant cooler assessments to benchmark the current status of the fed steer and heifer beef industry in the United States. In-plant cooler assessments ( = 9,106 carcasses) were conducted at 30 facilities, where approximately 10% of a single day's production were evaluated for USDA quality grade (QG) and yield grade (YG) factors. Frequencies of evaluated traits were 66.5% steer and 33.4% heifer sex classes and 82.9% native, 15.9% dairy-type, and 1.2% estimated breed types. Mean USDA YG factors were 1.42 cm for adjusted fat thickness, 89.5 cm for LM area, 390.3 kg for HCW, and 1.9% for KPH. Mean USDA YG was 3.1, with a frequency distribution of 9.6% YG 1, 36.7% YG 2, 39.2% YG 3, 12.0% YG 4, and 2.5% YG 5. Mean USDA QG traits were Small for marbling score, A for overall maturity, A55 for lean maturity, and A for skeletal maturity. Mean USDA QG was Select with a frequency distribution of QG of 3.8% Prime, 67.3% Choice, 23.2% Select, and 5.6% lower score. Lower score included dark cutter (1.9%), blood splash (0.1%), and hard bone, which are USDA overall maturity scores of C or older (1.8%). Marbling score distributions were 0.85% Slightly Abundant or greater, 7.63% Moderate, 23.54% Modest, 39.63% Small, 23.62% Slight, and 0.83% Traces or less. Carcasses that were Choice or Select and USDA YG 2 or 3 accounted for 70.7% of the carcasses evaluated. Compared with the previous NBQA, we found a numerical increase in mean USDA YG, USDA QG, adjusted fat thickness, HCW, LM area, and marbling score with an increase in dairy-type carcasses and percentage of carcasses grading USDA Prime and Choice as well as frequency of USDA YG 4 and 5. The findings from this study will be used by all segments of the industry to understand and improve the quality of fed steer and heifer beef that is being produced.

The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m2 to 59.09 m2. Area allotted per animal averaged 1.13 m2 and ranged from 0.85 m2 to 2.28 m2. A total of 96.8% of cattle received a mobility score of 1 (walks easily, no apparent lameness). Identification types (35.1% had multiple) were lot visual tags (61.5%), individual tags (55.0%), electronic tags (16.9%), metal-clip tags (9.2%), bar-coded tags (0.05%), wattles (0.01%), and other (2.6%). Cattle were black-hided (57.8%), Holstein (20.4%), red-hided (10.5%), yellow-hided (4.8%), gray-hided (2.9%), brown-hided (1.3%), and white-hided (1.1%). Unbranded hides were observed on 74.3% of cattle; 18.6% had brands located on the butt, 6.3% on the side, and 1.3% on the shoulder (values exceed 100% due to multiple brands). For hide-on carcasses, 37.7% displayed no mud or manure; specific locations for mud or manure were legs (40.8%), belly (33.0%), tail region (15.5%), side (6.8%), and top-line (3.9%). Cattle without horns represented 83.3% of the sample, and cattle that did have horns measured: < 2.54 cm (5.5%), 2.54 to 12.7 cm (8.3%), and > 12.7 cm (2.9%). Carcasses without bruises represented 61.1% of those sampled, whereas 28.2% had 1, 8.2% had 2, 2.1% had 3, and 0.3% had 4 bruises. Of those carcasses with a bruise, the bruise was located on the loin (29.7%), round (27.8%), chuck (16.4%), rib (14.4%), and brisket/plate/flank (11.6%). Frequencies of offal condemnations were livers (30.8%), lungs (18.2%), viscera (16.3%), hearts (11.1%), heads (2.7%), and tongues (2.0%). Compared to NBQA-2011, fewer cattle were identified for traceability, fewer were black-hided, a greater number were Holstein cattle, more with no brand and no horns, fewer without bruises, more liver, lung, and viscera condemnations, and fewer heads and tongues were condemned. The NBQA remains an influential survey for the U.S. beef industry to provide benchmarks and strategic plans for continued improvement of beef quality and consistency.

ObjectivesAnimal-sourced foods (ASFs), such as meat, provide nutrients that are beneficial for physical and cognitive development, especially in developing countries. Despite Ethiopia containing Africa’s largest inventory of livestock, market structure and inefficiencies in livestock and meat industries contribute to low-per capita consumption of meat. The combination of extensive periods of fasting from ASFs, knowledge gaps in hygienic handling and sanitation, lack of infrastructure and preservation, and weakly enforced food safety regulations contribute food safety risks in an already protein-deficient population. The objective of this study is to develop a dried beef jerky procedure that will reduce pathogen loads in meat, improve shelf stability, and increase access to ASFs in Ethiopia.Materials and MethodsChallenge studies were performed to validate a restructured jerky production process for control of five serotypes of Salmonella enterica (Saint Paul, Anatum, Typhimurium, Newport, Dublin) and three strains of E. coli O157:H7, within the constraints of equipment and ingredients available in Ethiopia. A traditional Ethiopian spice mixture was added to lean ground beef (94% lean, 6% fat), and in separate trials apple cider vinegar and pureed raisins were incorporated at varying percentages of the overall weight. The ground meat mixture was formed into strips and dehydrated to achieve aw of less than 0.70 for shelf stability and samples were plated for enumeration before and after drying. A consumer taste panel was conducted with treatments (0% and 15% raisin inclusion) to determine the acceptability of Ethiopian consumers. Sixteen Ethiopian consumers (10 men and 6 women) were asked to answer study-related questions and evaluate jerky products on visual appeal, texture, off-flavor, and overall liking on a 10-point hedonic scale.ResultsVinegar inclusion negatively impacted log CFU reductions of S. enterica as the control demonstrated significantly higher (P = 0.04) reductions than treatments including vinegar at 0.5, 1, and 2%. Including 15% raisins (w/w) in the meat and spice mixture resulted in an increased (P < 0.0001) log CFU reduction of S. enterica (5.41 CFU/g) versus the control (4.44 CFU/g) and all treatments achieved greater than 6-log CFU/g reduction of E. coli O157:H7.ConclusionIncluding raisins reduces S. enterica loads versus the control and all formulations exceeded a 6.0 log CFU/g reduction of E. coli O157:H7, in a restructured beef jerky product. A restructured jerky product could provide butchers with an additional marketing avenue and opportunity to reduce waste and pathogen loads in beef. Ethiopian consumers would also have an option for a commercially available, shelf-stable product which could provide additional protein to their diet that is easy to store and transport.

The Florida 4-H Poultry BBQ program has existed for years, and the program for red meat cookery has been a huge success in Tennessee 4-H. With sponsorship for the winners at the state level, the Florida 4-H Tailgate Contest program will be a success in Florida as well. This program will strive to promote enjoyable outdoor cooking experiences, encourage the incorporation of animal protein in the diet in order to combat childhood obesity, improve youth nutritional knowledge and cooking skills, and impart knowledge about safe handling and proper degree of doneness to produce safe and delicious meat dishes. This 2-page fact sheet is the fourth publication in the Florida 4-H Tailgateseries, and it discusses smoking and slow cooking meat. Written by Chad Carr, Brian Estevez, Sonja Crawford, Jason Scheffler, George Baker, Ed Jennings, and Mark Mauldin, and published by the 4-H Youth Development Department, December 2016. ­http://edis.ifas.ufl.edu/4h375

The Florida 4-H Poultry BBQ program has existed for years, and the program for red meat cookery has been a huge success in Tennessee 4-H. With sponsorship for the winners at the state level, the Florida 4-H Tailgate Contest program will be a success in Florida as well. This program will strive to promote enjoyable outdoor cooking experiences, encourage the incorporation of animal protein in the diet in order to combat childhood obesity, improve youth nutritional knowledge and cooking skills, and impart knowledge about safe handling and proper degree of doneness to produce safe and delicious meat dishes. This 2-page fact sheet is the third publication in the Florida 4-H Tailgateseries, and it discusses fire-building. Written by Chad Carr, Brian Estevez, Sonja Crawford, Jason Scheffler, George Baker, Ed Jennings, and Mark Mauldin, and published by the 4-H Youth Development Department, December 2016. ­http://edis.ifas.ufl.edu/4h374

La Ley de Modernización de la Seguridad Alimentaria (FSMA) se convirtió en ley en enero de 2011 y se considera la reforma más amplia de las normas de seguridad alimentaria en 70 años. Primero, se establecieron las regulaciones sobre alimentos para el consumo humano luego con la contribución de la industria, la academia, y los consumidores y otras agencias, se modificaron para adaptarse mejor a la producción de alimentos para animales. En Florida, estas nuevas regulaciones se aplican a las instalaciones que fabrican, procesan, empacan o almacenan alimentos o ingredientes para animales. El objetivo principal de estas regulaciones es garantizar alimentos seguros para los animales, las personas que manejan el alimento y las personas que consumen productos derivados de animales. This 4-page document is the Spanish version of The Food Safety Modernization Act (FSMA) Preventive Controls for Animal Food. Written by Francisco Rivera, Chad Carr, and Jason M. Scheffler, and published by the UF/IFAS Department of Animal Sciences, February 2019. http://edis.ifas.ufl.edu/an352

The quality grade system used in the United States to identify carcasses with superior eating satisfaction to consumers is based on the amount of intramuscular fat (marbling) within the ribeye and the maturity of the carcass. However, the most important quality attribute for consumers is tenderness. The objective of this study was to investigate the relationship between quality grade and tenderness assessed by slice shear force in strip loin steaks from Brangus cattle. Brangus steers (n = 860) were harvested when they reached approximately 1.27 cm fat over the ribeye. Hot carcass weight (HCW), dressing percentage (DP), marbling score (MARB; 100 to 199 = practically devoid, 200 to 299 = traces, 300 to 399=slight, 400 to 499=small, 500 to 599=modest, 600 to 699=moderate, 700 to 799=slightly abundant, 800 to 899=moderately abundant, and 900 to 999=abundant), ribeye area (REA), fat over the eye (FOE), and kidney pelvic and heart fat percentage (KPH) were evaluated for each animal. Quality grades and yield grades were calculated according to industry standards. A steak from the longissimus lumborum muscle was collected from each carcass, aged for 14 d and used for slice shear force testing to determine the tenderness. Data was analyzed with a general linear model with cooking loss, ranch, and feedlot as fixed effects. The quality grades ranged from high standard to average prime and the average of slice shear force values was 26.09 ± 8.76 kg. Quality grade had a significant effect on Slice Shear Force values (P = 0.0078), showing that quality grade significantly impacts tenderness. However, there was a high level of variation in Slice Shear Force values within quality grades. This indicates that carcasses with high quality grades could have meat with unacceptable tenderness, which could affect the demand for beef products.

El decreto de Modernización de la Seguridad Alimentaria (FSMA por sus siglas en inglés) fue firmado en Enero del 2011. Dicho documento intenta cambiar el enfoque de la seguridad alimentaria hacia prevención en lugar de reacción ante eventos relacionados con alimentos. Determinar si un peligro requiere un control preventivo depende de la frecuencia y la gravedad del peligro, el cual varía de acuerdo a la instalación y la especie alimentada. This 5-page fact sheet is the Spanish version of EDIS document AN344, Common Hazards to Consider During Manufacturing of Feeds for Horses. Written by Ana Margarita Arias, Taylor N. Langford, Carissa Wickens, Lori Warren, and Jason M. Scheffler, and published by the UF/IFAS Department of Animal Sciences, July 2018. http://edis.ifas.ufl.edu/an345

The Food Safety Modernization Act (FSMA) was signed into law in January of 2011. This law requires complying facilities that process, pack, or hold animal feed to develop and implement a risked-based preventive controls food safety plan. This 5-page fact sheet assists personnel at facilities working with feed for horses conduct a thorough hazard analysis, a core component of the food safety plan. Written by Jason M. Scheffler, Taylor N. Langford, Carissa Wickens, and Lori Warren, and published by the UF/IFAS Department of Animal Sciences, June 2018. https://edis.ifas.ufl.edu/an344

This 6-page document provides a list of common hazards to consider in the manufacturing of cattle feeds. It discusses the importance of preventing hazards, methods of prevention, and common physical, biological, and chemical hazards. Written by Taylor Langford, Matthew Hersom, Luiz Ferraretto, Antonio Faciola, Chad Carr, and Jason Scheffler, and published by the UF/IFAS Department of Animal Sciences, March 2018. http://edis.ifas.ufl.edu/an343

The objective of this study was to determine the effect of early weaning followed by a period of high-grain feeding on plasma acetate kinetics and signaling protein phosphorylation in LM tissue of growing steers. We hypothesized that early grain feeding would result in altered cell signaling and acetate use to support observed improvements in carcass gain and marbling. Fall-born Angus × Simmental steers were weaned at 106 ± 4 d of age (early weaned [EW]; n = 6) and fed a high-grain diet for 148 d or remained with their dams (normal weaned [NW]; n = 6) on pasture until weaning at 251 ± 5 d of age. Both treatments were subsequently combined and grazed on mixed summer pasture to 394 ± 5 d of age followed by a feedlot ration until harvest at 513 ± 5 d of age. Longissimus muscle tissue biopsies were collected at 253 ± 5 and 394 ± 5 d of age and at harvest. Total and phosphorylated forms of 5' adenosine monophosphate-activated protein kinase (AMPK) and downstream proteins of the mammalian target of rapamycin signaling pathway were determined by western blotting. Eight steers were used to assess acetate clearance at different age points via a bolus infusion of acetate (4 mmol/kg of BW). Early weaned steers had greater (P < 0.05) ADG than NW steers during the early grain feeding period. Phosphorylated to total ratios of ribosomal protein S6 (rpS6) and ribosomal protein S6 kinase 1 (S6K1) were significantly different during the early grain feeding period. Phosphorylated to total ratios of S6K1, rpS6, acetyl-CoA carboxylase, and 4E binding protein 1 and the absolute amount of phosphorylated AMPK were correlated with ADG, explaining 46% of the variance. Acetate clearance rates were less (P < 0.05) and synthesis rates were greater (P = 0.06) in EW steers during early grain feeding. Acetate synthesis rates were also greater (P < 0.05) in NW steers at harvest, suggesting a permanent shift in the gut microflora or gut function in response to the treatment. Neither treatment nor acetate infusion significantly affected plasma glucose or insulin concentrations. Plasma β-hydroxybutyric acid concentrations increased with acetate infusion (P < 0.05). Based on these results, altered cell signaling during the early grain feeding period likely mediated increased protein deposition, leading to increased carcass weights, but observed changes in acetate appearance and clearance rates do not appear to explain the observed differences in intramuscular fat deposition during the terminal feeding period.

The objective of this study was to determine the influence of Brahman genetics on muscle contractile and metabolic phenotype and postmortem proteolysis. Cattle used in this study represent a continuous spectrum of Angus-Brahman genetic variation. Steers were harvested and Longissimus samples were collected at 1.5h, 24h, and 14d postmortem. Proteolysis during the 14d aging period was evaluated, along with Warner-Bratzler shear force (WBSF) and trained sensory panel tenderness. Myosin heavy chain composition and enzymatic activity were used to evaluate fiber type characteristics. As Brahman influence increased, WBSF increased and sensory tenderness decreased. Calpain-1 autolysis decreased as Brahman percentage increased, and corresponded with reduced degradation of troponin-T, desmin, and titin. Increasing Brahman percentage was associated with greater citrate synthase activity and greater cross-sectional area of type IIx fibers. Brahman-influenced cattle produced tougher steaks and exhibited decreased protein degradation. Thus, Brahman genetics impacted not only the calpain-calpastatin system, but also muscle fiber size and metabolic properties.

Beef from Bos taurus indicus is associated with toughness compared to Bos taurus taurus, suggesting there is antagonism between adaptability to heat and beef quality. Resistance to cellular stress in muscle may be protective postmortem, thereby delaying its conversion to meat. Therefore, our objective was to determine pH decline, calpain-1 and caspase 3 activation, and proteolysis in different biological cattle types. Angus, Brangus, and Brahman steers (n = 18) were harvested, and Longissimus lumborum were assessed postmortem for pH decline, ATP content, protease activation, and calpastatin content; and myofibrillar protein degradation was evaluated in beef aged to 14d. Brahman Longissimus lumborum exhibited resistance to pH decline, greater ATP content at 1 h, and delayed calpain-1 autolysis. Although content of caspase-3 zymogen was lower in Brahman, there was no evidence of caspase-3 mediated proteolysis. Greater resistance to energetic and pH changes early postmortem in Brahman Longissimus lumborum are associated with calpain-1 autolysis but not mitochondria mediated apoptosis.

The study was conducted to determine effects of dietary supplementation with a blend of antioxidants (ethoxyquin and propyl gallate) on carcass characteristics, meat quality, and fatty acid profile in finishing pigs fed a diet high in oxidants. A total of 100 crossbred barrows (10.9±1.4 kg BW, 36±2 d of age) were randomly allotted to 5 diet treatments (5 replicate pens per treatment, 4 pigs per pen). Treatments included: 1) HO: high oxidant diet containing 5% oxidized soy oil and 10% PUFA source which contributed 5.56% crude fat and 2.05% docosahexanoic acid (DHA) to the diet; 2) VE: the HO diet with 11 IU/kg of added vitamin E; 3) AOX: the HO diet with antioxidant blend (135 mg/kg); 4) VE+AOX: the HO diet with both vitamin E and antioxidant blend; and 5) SC: a standard corn-soy control diet with nonoxidized oil and no PUFA source. The trial lasted for 118 d; on d 83, the HO diet pigs were switched to the SC diet due to very poor health. From that point, the VE pigs displayed the poorest performance. On d 118, 2 pigs from each pen were harvested for sampling. Compared to pigs fed SC diet, the HO and VE pigs (P 0.05), except a* value (redness) and belly firmness. Visible yellow coloration of backfat and lipofuscin in HO and VE pigs was observed at harvest at d 118. The high oxidant diet resulted in greater concentration of DHA in backfat (P

The Food Safety Modernization Act (FSMA) was signed into law in January of 2011. This law requires complying facilities that process, pack, or hold animal feed to develop and implement a risked-based preventive controls food safety plan. This 5-page fact sheet assists personnel at facilities working with feed for horses conduct a thorough hazard analysis, a core component of the food safety plan. Written by Jason M. Scheffler, Taylor N. Langford, Carissa Wickens, and Lori Warren, and published by the UF/IFAS Department of Animal Sciences, June 2018. https://edis.ifas.ufl.edu/an344

Pigs with the AMP-activated protein kinase γ3 R200Q (AMPKγ3(R200Q)) mutation generate pork with low ultimate pH (pHu). We hypothesized that reducing muscle creatine (Cr) and phosphocreatine (PCr) may accelerate postmortem ATP consumption and prevent extended pH decline in AMPKγ3(R200Q) longissimus muscle. Wild type and AMPKγ3(R200Q) pigs were assigned to control diet or diet supplemented with the creatine analog β-guanidinopropionic acid (β-GPA, 1%) for 2 wk. β-GPA reduced muscle PCr (P = 0.006) and total Cr (P0.0001). In general, AMPKγ3(R200Q)+β-GPA exhibited more rapid metabolism than control, AMPKγ3(R200Q), and β-GPA treatment, evidenced by more rapid loss of ATP, more rapid increase in IMP, and decreased pH during the first 90 min postmortem. Overall, pHu was similar despite elevated glycogen (AMPKγ3(R200Q)), reduced total Cr (β-GPA) or both (AMPKγ3(R200Q)+β-GPA). Thus, reducing muscle phosphagens did not affect pHu in AMPKγ3(R200Q) muscle, but it hastened ATP depletion and pH decline.

Early weaning of calves to a high concentrate diet results in greater fat deposition and suggests early postnatal metabolic imprinting events may be exploited as a management tool to improve cattle value. Our objective was to implement a short, high energy dietary intervention before a typical grazing period to manipulate intramuscular fat deposition in finishing cattle. Fall-born, Angus-sired steer calves (n = 24) were stratified by sire and randomly assigned to normal weaned (NW) or metabolic-imprinted (MIP) treatments. At 105 ± 6d (135kg), MIP calves were transitioned to a diet containing 20% CP and 1.26 Mcal/kg NEg. Metabolic-imprinted calves were fed ad libitum as a group. Normal weaned calves remained on their dam until 253 ± 6 d of age. At this time, treatment groups were combined and grazed for 156 d on a mixed summer pasture. Following the grazing phase, steers were adapted to a corn silage-based feedlot diet and performance was monitored on 28-d intervals. Calves were staged for harvest based on backfat endpoint (target 1.0 to 1.2 cm). Metabolic-imprinted calves were heavier (P0.05) than NW calves (341 vs. 265 ± 4.2 kg) at normal weaning age. During the grazing phase, NW steers gained more weight than (P0.05) MIP steers (0.69 vs. 0.35 ± 0.03 kg/d). Feedlot performance and USDA yield grade were similar (P0.20) between treatments. However, MIP steers produced heavier (P0.05) carcasses (564 vs. 524 ± 5.6 kg) with higher (P0.001) marbling scores (645 vs. 517 ± 23). Therefore, calves consuming a high concentrate diet for 148 d after early weaning produced higher quality carcasses. This suggests early weaning and feeding a high concentrate before grazing is a viable strategy to increase marbling deposition compared with a traditional production system.

Rate and extent of postmortem metabolism control pork quality development. Our objective was to evaluate the role of the phosphagen system (phosphocreatine, PCr; and creatine, Cr) on metabolism and pork quality. Muscle PCr and Cr were manipulated by feeding pigs the creatine analogue, β-guanidinopropionic acid (β-GPA). In experiment 1, pigs received standard (control) diet or β-GPA supplemented (2%) diet (1 wk or 2 wk). Supplementation with β-GPA (2 wk) decreased total Cr (PCr+Cr; P=0.02) and improved pork color (decreased reflectance, P=0.003); however, β-GPA supplementation reduced growth performance (P=0.007). To separate effects of phosphagen system and growth, a second experiment was conducted with control, pair-fed, and 2 wk β-GPA (1%) supplementation; pigs were also offered a control or β-GPA supplemented flavored beverage. Neither treatment influenced pork quality. Immediately postmortem, ATP/ADP was higher in control compared to pair-fed (P0.05); subsequently, ATP/ADP was similar among all groups. Loss of the phosphagen system may lead to adaptive changes that promote conservation of cellular ATP.

Extent of postmortem pH decline influences meat quality development. To better understand physiological determination of ultimate pH (pH u ), we utilized female and castrated male pigs from a line whose selection index includes differentiated pH u . All genotypes of AMP-activated protein kinase γ3 subunit (AMPKγ3) V199I site were present. The mutant 199II genotype increased pH u , but only in castrated males. Genotype affected glycolytic potential (GP), but GP was weakly associated with pH u . A subset of animals was selected based on low (− Gly) and high (+ Gly) residual glycogen content, and compared with AMPKγ3 200Q, which is associated with low pH u . Both + Gly and 200Q muscle contained glycolytic substrate at 24 h; however, 200Q muscle generated low pH u and greater lactate compared to + Gly. Additionally,− Gly and + Gly groups exhibited similar pH u despite a large difference in GP. In conclusion, high GP does not appear to directly impact the extent of postmortem pH decline.

The Florida 4-H Poultry BBQ program has existed for years, and the program for red meat cookery has been a huge success in Tennessee 4-H. With sponsorship for the winners at the state level, the Florida 4-H Tailgate Contest program will be a success in Florida as well. This program will strive to promote enjoyable outdoor cooking experiences, encourage the incorporation of animal protein in the diet in order to combat childhood obesity, improve youth nutritional knowledge and cooking skills, and impart knowledge about safe handling and proper degree of doneness to produce safe and delicious meat dishes. This 2-page fact sheet is the first publication in the Florida 4-H Tailgate series, and it discusses cooking equipment. Written by Chad Carr, Brian Estevez, Sonja Crawford, Jason Scheffler, George Baker, Ed Jennings, and Mark Mauldin, and published by the 4-H Youth Development Department, July 2016.­http://edis.ifas.ufl.edu/4h372

The signal transduction cascades that maintain muscle mass remain to be fully defined. Herein, we report that inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling in vitro decreases myotube size and protein content after 3-day treatment with a MEK inhibitor. Neither p38 nor JNK inhibitors had any effect on myotube size or morphology. ERK1/2 inhibition also upregulated gene transcription of atrogin-1 and muscle-specific RING finger protein 1 and downregulated the phosphorylation of Akt and its downstream kinases. Forced expression of enhanced green fluorescent protein-tagged MAPK phosphatase 1 (MKP-1) in soleus and gastrocnemius muscles decreased both fiber size and reporter activity. This atrophic effect of MKP-1 was time dependent. Analysis of the reporter activity in vivo revealed that the activities of nuclear factor-κB and 26S proteasome were differentially activated in slow and fast muscles, suggesting muscle type-specific mechanisms may be utilized. Together, these findings suggest that MAPK signaling is necessary for the maintenance of skeletal muscle mass because inhibition of these signaling cascades elicits muscle atrophy in vitro and in vivo.

Skeletal muscle is composed of diverse fiber types, yet the underlying molecular mechanisms responsible for this diversification remain unclear. Herein, we report that the extracellular signal-regulated kinase (ERK) 1/2 pathway, but not p38 or c-Jun NH(2)-terminal kinase (JNK), is preferentially activated in fast-twitch muscles. Pharmacological blocking of ERK1/2 pathway increased slow-twitch fiber type-specific reporter activity and repressed those associated with the fast-twitch fiber phenotype in vitro. Overexpression of a constitutively active ERK2 had an opposite effect. Inhibition of ERK signaling in cultured myotubes increased slow-twitch fiber-specific protein accumulation while repressing those characteristic of fast-twitch fibers. Overexpression of MAP kinase phosphatase-1 (MKP1) in mouse and rat muscle fibers containing almost exclusively type IIb or IIx fast myosin heavy chain (MyHC) isoforms induced de novo synthesis of the slower, more oxidative type IIa and I MyHCs in a time-dependent manner. Conversion to the slower phenotype was confirmed by up-regulation of slow reporter gene activity and down-regulation of fast reporter activities in response to forced MKP1 expression in vivo. In addition, activation of ERK2 signaling induced up-regulation of fast-twitch fiber program in soleus. These data suggest that the MAPK signaling, most likely the ERK1/2 pathway, is necessary to preserve the fast-twitch fiber phenotype with a concomitant repression of slow-twitch fiber program.

Our objective was to determine the effect of repeated use of implants on feedlot performance and carcass characteristics of Holstein cattle. Holstein steers (n = 128) weighing an average of 211 kg were blocked by weight and randomly assigned to 16 pens. At the start of the trial (d 0), pens were assigned to one of four treatments: 1) nonimplanted control (C); 2) implant on d 0, 112, and 224 (T3); 3) implant on d 112 and 224 (T2); and 4) implant on d 224 (T1). Component TE-S implants (120 mg of trenbolone acetate and 24 mg of estradiol per implant) were used for all treatments during the 291-d feeding period. Over the course of the study, T2 and T3 cattle had greater ADG and final weights than C and T1 cattle (P or = 0.26). Longissimus muscle areas (LMA) of T2 and T3 carcasses were larger than LMA of C (P < 0.01). No USDA Select carcasses were produced from C cattle, whereas the percentage of Select carcasses from implanted cattle ranged from 10 to 18%. Skeletal maturity advanced (P < 0.05) progressively with each additional implant. Steaks from T3 carcasses had a higher percentage of protein than controls (P < 0.05) and were less tender than all other treatments (P < 0.05). Repeated administration of combination trenbolone acetate and estradiol implants increased ADG and resulted in heavier carcasses with larger LMA. Administration of three successive implants decreased tenderness of Holstein beef, and resulted in more advanced skeletal maturity scores.

An inverse relationship between skeletal muscle fiber cross-sectional area (CSA) and oxidative capacity suggests that muscle fibers hypertrophy at the expense of oxidative capacity. Therefore, our objective was to utilize pigs possessing mutations associated with increased oxidative capacity [AMP-activated protein kinase (AMPKγ3R200Q)] or fiber hypertrophy [ryanodine receptor 1 (RyR1R615C)] to determine if these events occur in parallel. Longissimus muscle was collected from wild-type (control), AMPKγ3R200Q, RyR1R615C, and AMPKγ3R200Q-RyR1R615Cpigs. Regardless of AMPK genotype, RyRR615Cincreased fiber CSA by 35%. In contrast, AMPKγ3R200Qpig muscle exhibited greater citrate synthase and β-hydroxyacyl CoA dehydrogenase activity. Isolated mitochondria from AMPKγ3R200Qmuscle had greater maximal, ADP-stimulated oxygen consumption rate. Additionally, AMPKγ3R200Qmuscle contained more (∼50%) of the mitochondrial proteins succinate dehydrogenase and cytochrome c oxidase and more mitochondrial DNA. Surprisingly, RyR1R615Cincreased mitochondrial proteins and DNA, but this was not associated with improved oxidative capacity, suggesting that altered energy metabolism in RyR1R615Cmuscle influences mitochondrial proliferation and protein turnover. Thus pigs that possess both AMPKγ3R200Qand RyRR615Cexhibit increased muscle fiber CSA as well as greater oxidative capacity. Together, our findings support the notion that hypertrophy and enhanced oxidative capacity can occur simultaneously in skeletal muscle and suggest that the signaling mechanisms controlling these events are independently regulated.

Muscles in most domestic animals differ in function and growth potential based largely on muscle fiber type composition. Though much is known about satellite cells (SC), information is limited regarding how populations of SC differ with muscle fiber type, especially in pigs. Therefore, the objective of this study was to isolate and culture SC from red (RST) and white (WST) portions of the semitendinosus muscle of neonatal and adult pigs and determine their capacity to proliferate, differentiate, and express various myosin heavy chain (MyHC) isoforms in vitro. Porcine satellite cells were isolated from RST and WST muscles of 6-wk-old and adult (>6-mo-old) pigs and cultured under standard conditions. Muscle from neonatal pigs yielded nearly 10 times more (P < 0.001) presumptive satellite cells as those from adult pigs, with fusion percentages close to 60% for the former. The RST yielded more (P < 0.001) SC per gram muscle compared to WST, 8.1 ± 0.2 × 10(4) cells versus 6.7 ± 0.1 × 10(4) cells/gram muscle in young pigs, and 9.7 ± 0.4 × 10(3) cells versus 5.5 ± 0.4 × 10(3) cells/gram muscle in adult pigs, respectively. Likewise, satellite cells from RST proliferated faster (P < 0.001) than those from WST across both ages, as indicated by a shorter cell doubling time, 18.6 ± 0.8 h versus 21.3 ± 0.9 h in young pigs, and 23.2 ± 0.7 h versus 26.7 ± 0.9 h in adult pigs, respectively. As a result of shorter times to confluence, satellite cells from RST also formed myotubes earlier than those SC originating from WST. Once induced, however, SC from WST differentiated and fused faster (P < 0.05) as evidenced by fusion percentage within the first 24 h, 41.6% versus 34.3%, respectively; but reached similar ultimate fusion percentages similar to WST by 48 h. Over 90% of MyHC expressed in maximally fused SC cultures from both RST and WST was restricted to the embryonic isoform. Type IIX MyHC mRNA was not detected in any culture. Myotube cultures from RST expressed more (P < 0.01) Type I MyHC isoform mRNA than those from WST, whereas those cultures from WST expressed more (P < 0.05) Type II (including Types IIA and IIB) MyHC transcripts. These data show SC cultures from porcine fast and slow muscles express MyHC profiles largely reflective of their muscle of origin and suggest satellite cells are partially restricted to a particular muscle phenotype in which they are juxtapositioned. Understanding the molecular nature of these intrinsic control mechanisms may lead to improved strategies for augmenting meat animal growth or muscle regeneration.