Amy Ziyu Zhou University of Guelph 1 INTRODUCTION The variation of pork carcass weight and leanness affects all sectors of the pork industry the producer the processor and the consumer ID: 808964
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The relationship of pork carcass weight, leanness parameters and iodine values in the Ontario commercial industry
Amy (Ziyu) ZhouUniversity of Guelph
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Slide2INTRODUCTION
The variation of pork carcass weight and leanness affects all sectors of the pork industry – the producer, the processor, and the consumer
Slide3Example Marketing grid
Table 1
. Example of a marketing grid used for assessing value to pork carcasses
a
.
Predicted Percent Lean, %
Yield Class Number
Hot carcass weight range, kg< 75.075.0 to 79.980.0 to 84.985.0 to 89.990.0 to 94.995.0 to 99.9100.0 to 104.9105.0 to 109.9110.0 to 114.9115.0 to 119.9> 120.0 > 64.01-50-15-824444440 63.0 to 64.02-50-15-824666640 62.0 to 62.93-50-15-824688640 61.0 to 61.94-50-15-824688640 60.0 to 60.95-50-15-824688640 59.0 to 59.96-50-15-824666640 58.0 to 58.97-50-15-1504444440 57.0 to 57.98-50-15-1500000000 56.0 to 56.99-50-15-15-8-8-8-8-8-8-8-8 < 56.010-50-15-15-15-15-15-15-15-15-15-15 aValue within the grid indicates premium or discounted price/cwt (45.4 kg).
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Slide4Electronic grading probe
Optical technologySingle insertion perpendicularly between the 3rd and 4
th
last rib and 7 cm off the mid-line at the Canadian grading sites to obtain the measurements of each individual carcass
DPG: CLY (%) = 68.1863 – 0.7833
f
+ 0.0689
m + 0.0080f2 – 0.0002m2 + 0.0006fmWhere CLY is the Canadian lean yield of the carcasses and f and m are the backfat thickness (mm) and muscle thickness (mm), respectively, measured by the corresponding probe (CPC 1994)4
Slide5Near-infrared spectroscopy
Composed of two knife-tipped stainless-steel probes with a diameter of 6 mm, planted 2 mm apart
The probe can be inserted into the blade end of the loin region at approximately 4 cm into the carcass, allowing it to come directly into contact with the adipose layers immediately below the skin
The instrument is then ejected slowly at small increments to record the optical reading at each position, where it is then used to form a three-dimensional image comprising of various wavelength absorption depth. The image is then used to predict a final estimated iodine value for the carcass measured
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Slide6Historical trends of pig growth
% primal composition
Typical pig carcass today
Carcass from 1992
Ham
31.5%
27.6%
Loin26.7%24.7%Belly17.5%19.0%Butt13.3%12.6%Picnic13.4%11.3%Total lean yield76.2%59.8%6
Slide7Carcass parameters
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Slide8Carcass traits
Mean
SD
Minimum
Maximum
Hot carcass weight, kg
107.54
8.1970.90156.90Fat deptha, mm18.534.155.5039.50Muscle deptha, mm67.569.7925.0083.00Predicted leanb yield, %61.031.9052.6067.00Iodine Value70.276.9551.15112.46a Measured at the third and fourth last rib, 7cm of the mid-lineb Predicted lean yield was calculated using the following equation: CLY = (%) = 68.1863 − (0.7833 × fat depth) + (0.0689 × muscle depth) +(0.0080 × fat depth2) − (0.0002 × muscle depth2) + (0.0006 × fat depth × muscle depth).Population summary statistics for carcass traits (N=37,488 carcasses)8
Slide9Carcass traits
Fat depth
Muscle depth
Predicted lean yield
Iodine value
Hot carcass weight, kg
0.322
0.0920-0.2860.0324Fat depth, mm -0.103-0.949-0.256Muscle depth, mm 0.3880.0673Predicted lean yield, % 0.256Pearson correlation coefficient (r) for carcass traits (N=37,488 carcasses)9
Slide10Figure 5.1. Prediction of fat depth using hot carcass weight the independent variable (N = 37, 488) R
2
= 0.1038, y= 0.6356x + 95.762
r
2
value
Correlation type
<0.12Weak0.13≤ r2 <0.45Moderater2 ≥0.46Strong10
Slide11Regression results
Graph
Regression equation
r
2
value
Predicting ability
Fat depth vs HCWy= 0.6356x + 95.7620.10WeakMuscle depth vs HCWy = 0.077x + 102.330.0085WeakPredicted lean yield vs HCWy = -1.234x + 182.820.0010WeakIodine value vs HCWy = 0.0382x + 104.860.0010Weak11
Slide12Regression results
Graph
Regression equation
r
2
value
Predicting ability
HCW vs Iodine valuey = 0.0275x + 67.3140.0010WeakFat depth vs Iodine valuey = - 0.428x + 78.1990.065WeakMuscle depth vs Iodine valuey = 0.0478x + 67.0390.0045WeakPredicted lean yield vs Iodine valuey = 0.09385x + 12.9930.066Weak12
Slide13Categorized by weight
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Slide14Distribution of pigs by weight
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Slide1515
Slide16Categorical results
Graph
Regression equation
r
2
value
Pearson correlation
(r)Correlation Fat depth vs HCWy = 1.5469x + 11.6220.98930.99*StrongMuscle depth vs HCWy = 1.6287x + 58.4330.64940.81*StrongPredicted lean yield vs HCWy = -0.614x + 63.7310.9945-0.99*StrongIodine value vs HCWy = -0.5704x + 73.9990.2617-0.52Moderate*P < 0.0516
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Slide18Categorized by iodine value
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Slide19Distribution of pigs by Iodine value
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Slide2020
Slide21Correlation results
Graph
Regression equation
r
2
value
Pearson correlation (r)
Correlation HCW vs Iodine valuey = 0.117x + 107.340.9000.974*StrongFat depth vs Iodine valuey = -1.083x + 20.4790.998-0.998*StrongMuscle depth vs Iodine valuey = 0.5396x + 66.5960.9990.997*StrongPredicted lean yield vs Iodine valuey = 0.5015x + 60.1230.9960.997*Strong*P<0.0521
Slide22Discussion
Iodine values can be affected by various factorsVariables not considered
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Slide23Conclusion
Heavier pigs have a greater fat depth, a greater muscle depth, a lower predicted lean yield, and inconclusive for iodine values Carcasses with greater iodine value is believed to be greater carcass weight, lower fat depth, greater muscle depth, and greater predicted lean yield
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Slide24Thank you
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