The relationship of pork carcass weight, leanness parameters and iodine values in the - PowerPoint Presentation

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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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INTRODUCTION

The variation of pork carcass weight and leanness affects all sectors of the pork industry – the producer, the processor, and the consumer

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Example 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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Electronic 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

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Near-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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Historical 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

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Carcass parameters

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Carcass 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

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Carcass 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

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Figure 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

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Regression 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

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Regression 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

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Categorized by weight

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Distribution of pigs by weight

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Categorical 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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Categorized by iodine value

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Distribution of pigs by Iodine value

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Correlation 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

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Discussion

Iodine values can be affected by various factorsVariables not considered

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Conclusion

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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Thank you

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