Protein profile and reactive oxygen species production in mitochondria from pigs divergently selected for residual feed intake

The world population is expected to hit 9 billion people by the year 2050. The need to efficiently and sustainably produce high quality nutritious food will be a key challenge for producers. Meat is a complete source of protein, B-vitamins, and other macronutrients, and a necessity for a balanced diet [1-2]. As the world population continues to grow and developing countries become more affluent, the demand for meat will increase. In order to efficiently and sustainably produce enough meat to satisfy the demand, research must be conducted to establish the biological differences between animals with differing feed efficiencies. It has long been established that traits such as breed, sex, age, and season (temperature) impact the ability of an animal to efficiently convert dietary energy to metabolic energy (ATP). However, these aforementioned factors do not explain all of the variations in efficiencies. These variations can be partly explained by calculating residual feed intake (RFI). The concept of RFI was developed to account for the difference between actual feed consumption and expected consumption given average daily gain [3] and backfat [4]. A low RFI value would indicate the animal is more efficient in the converting dietary energy to metabolic energy than its contemporaries. Similarly an animal with a high RFI value would consume more than expected based on average daily gain and backfat. To understand and improve efficiency in meat production, the molecular differences between high and low RFI animals need to be better characterized. One of the end products of the conversion of dietary energy to metabolic energy is ATP. ATP is the metabolic currency of the cell. The mitochondria, known as the power house of the cell, generates up to 90% of ATP produced by the cell. The molecular make up of the mitochondria may impact the efficiency of an animal. Investigations into the electron transport chain and the protein profile of mitochondria may provide evidence for the observed differences in efficiencies from animals genetically selected from RFI. The electron transport chain is responsible for the conversion of the metabolic products originating from the TCA cycle into an energy gradient that is used to synthesize ATP from ADP. Superoxide anions are a form of reactive oxygen species (ROS) that originate from electron transport. Superoxide anions can cause oxidative stress and damage to cells and proteins. Energy is required to repair this oxidative damage, potentially leading to the partitioning of dietary energy away from protein accretion and growth towards cellular repair and replacement. In addition to ROS damage, the protein profile of mitochondria may hold clues as to the overall molecular differences between animals genetically selected for high and low RFI. Changes in the abundance of proteins related to ATP production, antioxidant defenses, and cell rescue could provide clues for the observed differences in RFI. Our overall objective was to determine potential molecular differences in the mitochondria using pigs genetically selected for RFI status as a model. Our data show there is a tissue specific increase in ROS production from the mitochondria in the less efficient, high RFI line. Coupled with the increase in ROS, proteins related to ATP production and cellular rescue were more abundant in the more efficient low RFI line. In addition to the data comparing RFI lines, a minimal difference in the protein profile was observed when animals separated by RFI phenotype irrespective of line. [1] McNeill S, Van Elswyk ME. Red meat in global nutrition. Meat Sci. 2012;92:166-73. [2] Murphy MM, Spungen JH, Bi X, Barraj LM. Fresh and fresh lean pork are substantial sources of key nutrients when these products are consumed by adults in the United States. Nutrition Research. 2011;31:776-83. [3] Boddicker N, Gabler NK, Spurlock ME, Nettleton D, Dekkers JCM. Effects of ad libitum and restricted feeding on early production performance and body composition of Yorkshire pigs selected for reduced residual feed intake. Anim. 2011;5:1344-53. [4] Koch RM, Gregory KE, Chambers D, Swiger LA. Efficiency of feed use in beef cattle. J. Anim. Sci. 1963;22:486-94

Influence of Beef Carcass Chilling Rate on Steak Case Life and Quality Traits

Objective To determine if beef carcass weight influences chilling rate, pH decline, beef color, case life and tenderness of steaks from the round, loin, rib and chuck

Temperature During Beef Product Transport Impacts Subprimal and Steak Yield

Objective The objective of this study was to determine the impact of ambient temperature during striploin and sirloin transport on moisture loss, color, and tenderness

Influence of Beef Carcass Chilling Rate on Steak Case Life and Quality Traits

Study Description: Twelve head of fed beef cattle were harvested at the SDSU Meat Laboratory over two days. Carcasses were allotted into two weight groups based on hot carcass weight (HCW): Heavyweight (HW) and Lightweight (LW). Data logging thermometers were placed in the left side of each carcass within the round, loin, rib, and chuck primals to track temperature decline. Carcass measurements including 12th rib fat thickness, ribeye area and marbling score were collected approximately 48 hours postmortem. Steaks from each primal were collected to measure Warner-Bratzler shear force (WBSF), objective and subjective color

Influence of Carcass Chilling System on Chuck, Loin, and Round Temperature Decline, Carcass Characteristics, and Tenderness

Objective Determine the effect of chilling systems on beef carcass temperature decline, carcass characteristics, and tenderness

Beef Carcass Weight and Quality Grade Influence Tenderness

Objective The objective was to investigate whether hot carcass weight (HCW) affected Warner-Bratzler shear force (WBSF) and tenderness formation of Denver, strip, and eye of round steaks from USDA Select (Se) and low Choice (LC) beef carcasses.Study Description Select and LC carcasses were selected at a commercial beef plant by HCW (light = 650–750 lb; middle = 850–950 lb; heavy = 1,025–1,150 lb). Steaks were fabricated and aged for 5, 10, and 14 days. Tenderness was determined through WBSF based on industry standards. Additionally, protein degradation was analyzed to determine tenderness formation

Evidence of decreased muscle protein turnover in gilts selected for low residual feed intake

The objective of this study was to evaluate the contribution of muscle protein turnover (synthesis and degradation) to the biological basis for genetic differences in finisher pigs selected for residual feed intake (RFI). Residual feed intake is defined as the difference between expected feed intake (based on the achieved rate of BW gain and backfat depth of individual pigs) and the observed feed intake of the individual pig. We hypothesized that protein turnover would be reduced in pigs selected for low RFI. Twelve gilts from a line selected for 7 generations for low RFI and 12 from a contemporary line selected for 2 generations for high RFI were paired by age and BW and fed a standard corn–soybean diet for 6 wk. Pigs were euthanized, muscle and liver samples were collected, and insulin signaling, protein synthesis, and protein degradation proteins were analyzed for expression and activities. Muscle from low RFI pigs tended to have less μ- and m-calpain activities (P = 0.10 and 0.09, respectively) and had significantly greater calpastatin activity and a decreased μ-calpain:calpastatin activity ratio (P \u3c 0.05). Muscle from low RFI pigs had less 20S proteasome activity compared with their high RFI counterparts (P\u3c 0.05). No differences in insulin signaling intermediates and translation initiation signaling proteins [mammalian target of rapamycin (mTOR) pathway] were observed (P \u3e 0.05). Postmortem proteolysis was determined in the LM from the eighth generation of the low RFI pigs versus their high RFI counterparts (n = 9 per line). Autolysis of μ-calpain was decreased in the low RFI pigs and less troponin-T degradation product was observed at 3 d postmortem (P \u3c 0.05), indicating slowed postmortem proteolysis during aging in the low RFI pigs. These data provide significant evidence that less protein degradation occurs in pigs selected for reduced RFI, and this may account for a significant portion of the increased efficiency observed in these animals

Protein profile and reactive oxygen species production in mitochondria from pigs divergently selected for residual feed intake

The world population is expected to hit 9 billion people by the year 2050. The need to efficiently and sustainably produce high quality nutritious food will be a key challenge for producers. Meat is a complete source of protein, B-vitamins, and other macronutrients, and a necessity for a balanced diet [1-2]. As the world population continues to grow and developing countries become more affluent, the demand for meat will increase. In order to efficiently and sustainably produce enough meat to satisfy the demand, research must be conducted to establish the biological differences between animals with differing feed efficiencies. It has long been established that traits such as breed, sex, age, and season (temperature) impact the ability of an animal to efficiently convert dietary energy to metabolic energy (ATP). However, these aforementioned factors do not explain all of the variations in efficiencies. These variations can be partly explained by calculating residual feed intake (RFI). The concept of RFI was developed to account for the difference between actual feed consumption and expected consumption given average daily gain [3] and backfat [4]. A low RFI value would indicate the animal is more efficient in the converting dietary energy to metabolic energy than its contemporaries. Similarly an animal with a high RFI value would consume more than expected based on average daily gain and backfat. To understand and improve efficiency in meat production, the molecular differences between high and low RFI animals need to be better characterized. One of the end products of the conversion of dietary energy to metabolic energy is ATP. ATP is the metabolic currency of the cell. The mitochondria, known as the "power house of the cell," generates up to 90% of ATP produced by the cell. The molecular make up of the mitochondria may impact the efficiency of an animal. Investigations into the electron transport chain and the protein profile of mitochondria may provide evidence for the observed differences in efficiencies from animals genetically selected from RFI. The electron transport chain is responsible for the conversion of the metabolic products originating from the TCA cycle into an energy gradient that is used to synthesize ATP from ADP. Superoxide anions are a form of reactive oxygen species (ROS) that originate from electron transport. Superoxide anions can cause oxidative stress and damage to cells and proteins. Energy is required to repair this oxidative damage, potentially leading to the partitioning of dietary energy away from protein accretion and growth towards cellular repair and replacement. In addition to ROS damage, the protein profile of mitochondria may hold clues as to the overall molecular differences between animals genetically selected for high and low RFI. Changes in the abundance of proteins related to ATP production, antioxidant defenses, and cell rescue could provide clues for the observed differences in RFI. Our overall objective was to determine potential molecular differences in the mitochondria using pigs genetically selected for RFI status as a model. Our data show there is a tissue specific increase in ROS production from the mitochondria in the less efficient, high RFI line. Coupled with the increase in ROS, proteins related to ATP production and cellular rescue were more abundant in the more efficient low RFI line. In addition to the data comparing RFI lines, a minimal difference in the protein profile was observed when animals separated by RFI phenotype irrespective of line. [1] McNeill S, Van Elswyk ME. Red meat in global nutrition. Meat Sci. 2012;92:166-73. [2] Murphy MM, Spungen JH, Bi X, Barraj LM. Fresh and fresh lean pork are substantial sources of key nutrients when these products are consumed by adults in the United States. Nutrition Research. 2011;31:776-83. [3] Boddicker N, Gabler NK, Spurlock ME, Nettleton D, Dekkers JCM. Effects of ad libitum and restricted feeding on early production performance and body composition of Yorkshire pigs selected for reduced residual feed intake. Anim. 2011;5:1344-53. [4] Koch RM, Gregory KE, Chambers D, Swiger LA. Efficiency of feed use in beef cattle. J. Anim. Sci. 1963;22:486-94.</p

Low-Voltage Electrical Stimulation of Beef Carcasses Slows Carcass Chilling Rate and Improves Steak Color

Electrical stimulation (ES) is used in beef slaughter plants to improve tenderness; however, varying levels of low-voltage ES have not been well characterized. The objective was to evaluate the influence of two levels of low-voltage ES on temperature decline, pH, glycolytic potential, and meat quality. Forty-two beef carcasses were chosen from a commercial packing facility. One side of each carcass received either 40 or 80 volts of ES for 60 s at 45 min postmortem. The paired side of each carcass did not receive ES (Control). Temperature loggers were placed in the sirloin of 12 carcasses to record temperature decline. Longissimus muscle pH was measured at 1, 12, and 24 h, and 3 d postmortem. Strip steaks were fabricated for determination of meat quality. A treatment by time interaction was observed for carcass temperature decline (p &lt; 0.001) where ES sides stayed warmer longer than Control sides. A treatment by time interaction was observed for pH decline with Control sides exhibiting an increased pH at 1 h postmortem (p &lt; 0.001). Instrumental color values were increased for ES compared to Control sides (p &lt; 0.001). These results indicate ES slows carcass temperature decline, hastens initial pH decline, and improves instrumental color. Similar results were observed between the ES treatments indicating either ES level may be used to achieve similar quality characteristics