swine stress and handling factors that impact pork quality
TRANSCRIPT
Dan Hale [email protected]!
Swine Stress and Handling Factors that Impact Pork Quality!
AMI!October 2014!
A defect is anything that impacts the value of pork or impairs consumer confidence!
What is Quality?!
Color!Drip Loss!Firmness!
Chemistry Of Meat Protein!Myofibrillar (contractile)!
~ 55% of total muscle protein but 70-80%+ of WHC and binding properties!
Stromal proteins (connective tissue)!10 - 15% of total muscle protein !primarily collagen!
!Sarcoplasmic proteins (water soluble, intracellular fluid)!
30% of total muscle protein (~ 20% of binding ability)!isoelectric points generally between pH 6 - pH 7!hundreds of enzymes in cells for energy, growth, etc.!most are relatively low molecular weight (small) proteins!
!
Chemistry Of Meat Protein!
– Myosin is generally considered the singly most important because:!
– Long filamentous molecule (similar to a 1 inch garden hose that is 8 feet long)!
– amino acid composition gives highly-charged, polar molecule!
– present in large quantity in lean muscle!
Drawing from Principle of Meat Science, 2001, Aberle, Forrest, Gerrard, Mills!
Drawing from Principle of Meat Science, 2001, Aberle, Forrest, Gerrard, Mills!
Chemistry Of Water!Water!
present in greatest quantity in most products!important to eating quality and economics!remember: water is both a meat component and a non-meat (added) ingredient!!Bound by proteins!In order to understand water in meat systems it is necessary to understand! water : protein interactions !water : water interactions!Water is a unique compound with a unique structure!!!!!!
H2O!
+H !H+!
O!
- -!
Water attracts Water!
Protein!Water!!!Water!Water!
�Free� water is loosely held and very dependent upon capillary space between and within proteins. !
Drawing from Principle of Meat Science, 2001, Aberle, Forrest, Gerrard, Mills!
pH and Binding Water!
Drawing from Principle of Meat Science, 2001, Aberle, Forrest, Gerrard, Mills!
protein – – – + – "! ! !+ !– + –!
pH 6.0 net charge = –3!
+H !H+!
O!
- -!
protein – H+ – – + – +H "! ! !+ !– + H+–!
pH 5.1 net charge = 0!!! Isoelectric Point!!
+3H +!
protein H+ – H+ – – + – H+ "! ! !+ ! H+ – + H+–!
pH 4.5 net charge = +2!
+2H +!
+H !H+!
O!
- -!
+ +!
!+ +!
!
!H2O! H2O! H2O!
pH 6.0! pH 5.1! pH 4.5!
Meat Color!
Hunter has been largely adopted for meat color measurement because!
L = lightness!a = redness (+) → green (-)!b = yellow (+) → blue (-)!
L measures Lightness " 100 - perfect whiteness " 0 - Black " !
a Redness +" Gray 0" Greenness -!
!
b Yellowness +" Gray 0" Blueness -!
Glucose Metabolism
Principles of Meat Science!Aberle et al. Textbook!
Glucose Metabolism Postmortem
Principles of Meat Science!Aberle et al. Textbook!
Hormonal Control
Adapted from Principles of Meat Science!Aberle et al. Textbook!
Pituitary Gland!
Adrenal Gland!
Thyroid Gland!
ACTH - Stimulation of corticoid release!Adrenocorticotropic hormone!!Corticoid - synthesis of carbohydrates, !maintenance of cell response!!Epinephrine and Norepinephrine - !Influence blood flow and heart rate, !breakdown glycogen and lipid!!Thyroid Gland - stimulation of !oxidative metabolism,!Increases metabolic rate!
Release of high levels of Ca2+ from the sarcoplasmic reticulum into the sarcoplasm which triggers an accelerated rate of postmortem glycolysis and is responsible for the high incidence of PSE observed in halothane pigs.!!Elevated muscle glycogen content and an extended duration of postmortem glycolysis can also result in PSE-like characteristics, as seen in RN– pigs. Rendement Napole or RN gene have elevated glycogen levels within the muscle, which in turn are converted into lactate postmortem. The elevated lactate levels produce acidic meat, which has decreased water holding capacity, and increases purge loss. !!Shifts in muscle fiber type toward higher proportions of glycolytic fibers may help explain the incidence of PSE. !
Genetics of PSE!Changes in Muscle Metabolism!
pH Decline in Pork
Sellier, P. and G. Monin. 1994. Genetics of pig meat quality- a review. J. Musc. Foods. 5: 187-219.!
Handling and Stress "and "
Meat Quality!
Genetics!Environment! Nutrition! Climatic! Handling! Transport!Genetic X Environment!
Stress and Pork Quality!
Measures of Stress
Stress Hormones (Cortisol, Catecholamine) !Insulin !Blood lactate !Blood pH !Ammonia !Lipid mobilization (Re-esterified) !Glycolytic potential (Muscle or Liver) !Liver glycogen !
Physiological Measures of Stress!
Blood Lactate a Handling System Evaluation Tool!
Lactate and Pork Quality!A group of 128 cross-bred barrows were used to determine the relationship between exsanguination blood lactate concentration ([LAC]) and carcass quality following commercial marketing conditions. !!After 10 h of feed withdrawal, pigs were loaded on a truck with a hydraulically lifted second deck and transported approximately 1 h to the slaughter facility. Pigs were rested for 8 h and stunned with carbon dioxide. Blood lactate concentration was measured on exsanguination blood. Higher lactate was associated with lower 60 min pH (P = 0.0004) and higher drip loss (P = 0.02)..!
Edwards, L. N., Engle, T. E., Correa, J. A., Paradis, M. A., Grandin, T., & Anderson, D. B. (2010). The relationship between exsanguination blood lactate concentration and carcass quality in slaughter pigs. Meat Science, 85(3), 435−440. !
Lactate Measured at Several Locations!
Meat Sci. 2010 Dec;86(4):938-44 The effects of pre-slaughter pig management from the farm to the processing plant on pork quality.Edwards LN1, Grandin T, Engle TE, Ritter MJ, Sosnicki AA, Carlson BA, Anderson DB.!
Hormel ; n=80, n=144) Each test animal was sampled 7 times during the market process using a low-stress blood sampling procedure. !!
Lactate and Negative Handling!
Characterized the relationship of pre-slaughter animal-handling events to exsanguination blood lactate concentration ([LAC]) in a commercial pork processing plant. !!
Edwards LN, Grandin T, Engle TE, Ritter MJ, Sosnicki AA, Carlson BA, Anderson DB. ... Meat Sci. 2010 Oct;86(2):384-90. !
Lactate and Negative Handling!
Pigs experiencing one or more events (i.e., jamming, rearing and/or backing up) while moving through a single-file chute had greater (Pb0.03) [LAC] than pigs that did not experience these.!!Pigs prodded in the crowd pen had greater (P = 0.03) [LAC] than pigs that were not prodded (Exp. 2). This study provides data demonstrating that specific pre-slaughter animal-handling events are related to post-slaughter [LAC] in a commercial setting. !!
Edwards LN, Grandin T, Engle TE, Ritter MJ, Sosnicki AA, Carlson BA, Anderson DB. ... Meat Sci. 2010 Oct;86(2):384-90. !!
Crossbred, halothane-free pigs (n =192) were processed in eight groups (24 pigs per group) on various days at one of two commercial processing plants operating different stunning systems (electrical and CO2 stunning in Plants A and B, respectively). In each group, half the pigs were exposed to either minimal or high preslaughter stress.!!Pigs in the minimal stress group were guided to the stunning area without the use of electric goads and were handled as calmly as possible, whereas pigs in the high-stress group were forced, by yells and electric goads, to move four times back and forth in the corridor leading to the stunning area.!!!
Preslaughter stress and muscle energy largely determine pork quality at two commercial processing plants E. Hambrecht, J. J. Eissen, R. I. J. Nooijen, B. J. Ducro, C. H. M. Smits, L. A. den Hartog and M. W. A. Verstegen J ANIM SCI 2004, 82:1401-1409.!
Pre-Slaughter Stress and Pork Quality!
High stress increased (P < 0.05) 30-min muscle temperature and de- creased (P < 0.05) 30-min muscle pH. !!Ultimate pH was increased (P < 0.05) and muscle glycolytic potential was decreased (P < 0.05) by high preslaughter stress. !!High stress resulted in inferior pork quality attributes (P < 0.05), including reflectance, electrical conductivity, filter paper moisture, drip loss, and L* value. The effect of stress was greater on water-holding capacity than on pork color, with drip losses increased by 56%. !!Of all stress indicators measured at exsanguination, only blood lactate was strongly correlated with pork quality attributes. !
Preslaughter stress and muscle energy largely determine pork quality at two commercial processing plants E. Hambrecht, J. J. Eissen, R. I. J. Nooijen, B. J. Ducro, C. H. M. Smits, L. A. den Hartog and M. W. A. VerstegenJ ANIM SCI 2004, 82:1401-1409.!
Pre-Slaughter Stress and Pork Quality (cont)!
Handling and Transport - Additive!
Transport Time and Resting Time!
André Fortin Canadian Journal of Animal Science, 2002, 82:(2) 141-150, 10.4141/A00-097!
1900 pigs. Transport times were 50 min and 2 h, and resting periods at the abattoir were < 30 min, 3 h and 6 h. !!Transport Time!The shorter (50 min) transport time was associated with the highest (P ≤ 0.05) incidence of pale and soft/exudative loins. !!A longer transport time reduced the incidence of pale and soft/exudative loins; it also increased (P ≤ 0.05) the incidence of dark and firm/dry loins; particularly during winter. !
André Fortin Canadian Journal of Animal Science, 2002, 82:(2) 141-150, 10.4141/A00-097!
1900 pigs. Transport times were 50 min and 2 h, and resting periods at the abattoir were < 30 min, 3 h and 6 h. !!Resting Time!A resting period of < 30 min resulted in the highest (P ≤ 0.01) incidence of pale and soft/exudative loins. !!A 3 h resting period significantly improved (P ≤ 0.01) quality by reducing the incidence of pale loins and soft/exudative loins. !!Extending the resting period from 3 h to 6 h provided inconsistent improvements in quality due to interactions with season (P ≤ 0.05) and producer/management (P ≤ 0.05). !
Transport Time and Resting Time (cont.)!
Water Sprinkling in the Summer!
The results of this study showed that the sprinkling protocol applied was effective, particularly in some trailer compartments, in reducing stress response and improving pork quality of pigs transported in pot-bellied trailers.!
Nannoni et al. 2013 Livestock Science Volume 160, Pages 124–131, February 2014 !
The water sprinkling system was activated for 5�min in the stationary truck, both at the farm (at the end of loading) and at the plant (immediately before unloading).!
1. Provide adequate pen space in holding pens at the plant. 6 sq feet !(.55sq meters) per 250lb (113kg) pig. All pigs must have room to lie down.!2. During hot weather wet animals down with sprinklers.!3. Allow 2 to 4 hours of rest prior to stunning.!4. Handle and drive animals quietly and reduce or eliminate electric prod usage. Excited pigs are more likely to have poorer quality pork. Pork quality can be ruined during the last five minutes prior to stunning. This is why it is so important to handle pigs quietly.!5. NEVER fill the forcing pen more than one half to three quarters full. Animals need room to turn so they can enter the race more easily.!6. Pigs must always have access to water.!7. Measuring the levels of lactate in the blood at bleeding can be used as a test to monitor handling in the stunning area. High lactate at bleeding is associated with higher drip loss and poorer pork quality.!
Preventing PSE (Pale Soft Exudative Pork) in Pigs!Temple Grandin!
Thank you to the following for materials used for this presentation!
http://www.grandin.com/!www.animalhandling.org/!Temple Grandin!Elisabeth Huff-Lonergan!Steven Lonergan!Floyd McKeith!Melvin Hunt!David Anderson!Lily Edwards Callaway!
Heat Shock Proteins (HSP)!Several heat shock proteins function as intra-cellular chaperones for other proteins. !!They play an important role in protein-protein interactions such as folding and assisting in the establishment of proper protein conformation (shape) and prevention of unwanted protein aggregation.!! By helping to stabilize partially unfolded proteins, HSPs aid in transporting proteins across membranes within the cell. !!HSPs also binds with cell membranes and maintains the integrity and stability of membranes !!
Heat Shock Proteins!All four Hsps tested (alpha-B-crystalline, Hsp27, Hsp70 and Hsp90) by ELISA in the LD tissue of pigs tended to decrease!after transportation. One possible mechanism resulting in poor meat quality in the LD after transport seems to be a decline in Hsp expression. Yu teal 2009 Meat Science 83 (2009) 474–478!!Statistical analysis indicated HSP90 level was significantly and negatively correlated with cooking loss, drip loss, and lightness (r = -0.797, -0.785, -0.604, respectively, P < 0.01). The results suggest that HSP90 may play a crucial role in water retention of meat and may be involved in postmortem pork meat quality development. Wang et al 2014 Food Chemistry 165 (2014) 337–341 !!