Hazelnut-Finished Pork in the Upper Midwest: A New High-Value Product From A Sustainable Production System

Final report for ONC19-056

Project Type: Partnership
Funds awarded in 2019: $39,777.00
Projected End Date: 02/28/2022
Grant Recipient: Bayfield County UW-Extension
Region: North Central
State: Iowa
Project Coordinator:
Jason Fischbach
Bayfield County UW-Extension
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Project Information

Summary:

With the recent development of improved hazelnut germplasm for growers in the Upper Midwest, the industry is poised for rapid expansion.  To facilitate this expansion the University of Wisconsin launched the Hazelnut Processing Accelerator in partnership with Northland College, the American Hazelnut Company, the Main Street Project, and the Bayfield Regional Food Producers Cooperative.  The purpose of the Accelerator is to develop processing technology and equipment optimized to hazelnuts grown in the Upper Midwest while providing a bridge processing facility until production volumes are sufficient to support a financially viable facility.  With more than two years of processing experience, we have identified waste streams that are not suitable for human food or require further processing that is too expensive at this time.  Such waste streams may be suitable for livestock feed.

This project will evaluate the feed quality of undersized nuts, half-cracked nuts, and mixtures of the kernel and shell fragments and conduct a feeding trial with pigs to quantify the effect of the feeds on carcass and meat quality.  Such information will allow pork producers and hazelnut growers in the Upper Midwest to capitalize on the growing market for mast-finished regional pork.

Results from the feeding trials indicate feeding hazelnuts (up to 30% replacement) will change the fatty acid profile of the pork without negatively affecting growth or pig performance.  Because of covid-19 restrictions, we were unable to perform consumer-tasting evaluations to quantify how the increase in oleic acid caused by the hazelnuts affected consumer preference.  From the work, we produced a relative feed value calculator growers can use to determine the feed value of hazelnut kernel or ground up whole in-shell hazelnuts. 

Project Objectives:
  1. Analyze the nutritional components of hazelnut screenings including: ground whole undersized nuts, half-cracked nuts, three mixtures of shell and kernel fragments.
  2. Evaluate the growth performance and meat quality of pigs finished with hazelnuts.
  3. Develop and publish a feeding program for hazelnut growers and pork producers for finishing pigs with hazelnuts.

Cooperators

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  • Jeff Jensen (Educator)

Research

Materials and methods:

The first step of the project was to aggregate in-shell hazelnuts from Midwestern producers.  To do so, we partnered with the American Hazelnut Company in Ashland, WI.  Their cracking and cleaning line does not easily handle hazelnuts with 10mm and small hazelnuts.  So, for this project we sorted out all the 10mm in-shell nuts from their line and then supplemented those with in-shell nuts (of all sizes) we purchased from other growers.  Because of the challenge of cracking and cleaning such small hazelnuts we wanted to evaluate the feed quality and growth responses to whole in-shell hazelnuts when ground up.

The feed component data compared to soybeans are show on slides 4 and 5 of the presentation: Lammers - 2020 - Hazelnut Finished Pork.  As the data show, hazelnut kernels have much higher fat, protein, and oleic acid content than soybeans, but when the shells are included the feed value drops significantly. The purpose, then, of our feeding trials was to evaluate the growth and carcass quality of pigs fed whole ground hazelnuts compared to a standard corn/soy diet.

In 2019, we conducted two feeding trials as described here.  Hazelnut kernels, shells, and undersized (diameter < 0.4 in) in-shell hazelnuts were analyzed using standard wet-chemistry techniques for feed analysis. The two feeding trials were conducted to evaluate the effect of diluting pig diets with ten percent in-shell hazelnuts. In each trial, 36 barrows (128 ± 2 lb) were sorted into 6 pens inside of the three mini-hoop barns (48 ft2/pig). Pens of pigs were randomly assigned to receive a balanced corn-soybean meal diet (control) or the control diet diluted with in-shell hazelnuts (90:10 control:in-shell hazelnuts). Hazelnuts were pulverized using a roller mill before incorporation into the diet. Pigs were individually weighed every 28 days and feed disappearance was recorded. For each trial, all pigs were harvested on the same day after either 68 or 69 days of feeding. Two chops were collected from each pig to assess pork quality. One cube (1 in2) of fat was removed from half of the chops (1 sample/pig) and analyzed for fatty acid profile.

In 2021, we fed 24 pigs divided into 6 pens of 4 pigs each.  The pigs were 150 lbs each at the start and were fed for 77 days until harvest.  Each pen received one of six different rations for the 77 days: standard corn/soybean meal control, control + 10% hazelnut kernels, control + 10% hazelnut shells, control + 10% ground in-shell hazelnuts, control + 20% ground in-shell hazelnuts, control + 30% ground in-shell hazelnuts.  As with the 2019 trial, pigs were weighed every 28 days and feed disappearance was recorded.  All pigs were harvested on the same day.  Fat from the pork chops were analyzed for fatty acid profile.

Research results and discussion:

The nutrient profile of hazelnut products are summarized in Table 1 and compared to reference values for corn grain and soybean meal. Hazelnut kernels are rich in unsaturated fatty acids particularly oleic (C18:1). In-shell hazelnuts have less crude fat and lower concentrations of specific fatty acids than hazelnut kernels but more than corn grain or soybean meal. Due to the shells, all fiber measures of the in-shell hazelnuts were much greater than the hazelnut kernels, corn grain, or soybean meal.

Pig performance and carcass characteristics are shown in Table 2. Growth rate, carcass weight, and carcass fat were not different across dietary treatment. Pigs fed diets diluted with 10% in-shell hazelnuts grew less efficiently requiring 6% more feed per unit of gain.

Quality characteristics of loin chops and fatty acid profile of backfat is presented in Table 3. Pork quality attributes were not different across dietary treatments. The fat from pigs fed diets containing in-shell hazelnuts had less saturated fat and more unsaturated fat. Oleic acid content was higher in the fat of pigs fed diets containing 10% in-shell hazelnuts as compared to the control diet.

Feeding in-shell hazelnuts to pigs may be an effective way to add value to nuts ill-suited for processing into products for human consumption. Acorn-finished pork is a high-value niche product in several parts of the world. The fatty acid profile of pork fat from acorn-fed pigs also has an elevated concentration of oleic and other monounsaturated fatty acids. Although fat from acorn-finished pigs is reported to have higher amounts of oleic acid than observed in this trial, feeding corn-soybean meal diets diluted with 10% in-shell hazelnuts effectively changed the fatty acid profile of pork fat.

In the 2021 trials, we attempted to find the the optimal balance point among hazelnut feeding level, pig performance, and fatty acid profile. Table 4 shows the energy of the six different rations and the performance of the pigs fed each of those diets.  Although we did not have enough true replication to separate the means statistically, the trends are interesting.  In general, there was little to no difference in average daily gain or hot carcass weight among the six rations.  Even the ration that had 30% of the control replaced with ground in-shell hazelnuts yielded pigs with similar hot carcass weights and daily gains. 

Table 5 shows the percent fat and energy of the rations along with the palmitic and oleic acid concentrations of the pork fat.  The higher the percentage of hazelnut kernel in the ration the lower the palmitic acid and the higher the oleic acid.    Together the data suggest that hazelnuts can be used to change the fatty acid profile of pork without negatively affecting growth compared to standard corn/soy rations.

Using the results from the trials, we produced a guide and Excel-based calculator tool to calculate the relative feed value of hazelnuts when feeding them to pigs.  The calculations are based on the replacement energy value of corn.

Restrictions due to Covid-19 prevented us from conducting the planned sensory tasting analysis.  Furthermore, UW-Platteville and Iowa State restrictions do not allow us to sell or provide pork harvested from the trial animals to the general public for consumer testing.  

Feeding acorns to pigs is known to change the fatty acid profile, as well, and such pork is marketed as a specialty product.  The best example of this is acorn fed iberian ham from spain.  Prices range from $67-$108/lb.  This high value is due to a combination of the pork itself, but also the very long curing process for the hams.  Whether Midwestern pork producers can produce such a high value product from hazelnut-fed pigs remains to be seen.

Table 1. Nutrient profile of hazelnut products and reference feedstuffs for pigs.

 

Hazelnut1

Corn2

Soybean Meal3

 

Kernels

Shells

< 0.4 in-shell nut

 

 

Dry matter, %

100.0

100.0

100.0

100.0

100.0

Crude protein, %

18.4

1.3

7.6

9.3

53.0

Lysine, %

0.5

0.0

0.2

0.3

3.3

Crude fiber, %

4.8

75.4

49.5

2.2

4.3

NDF, %

12.2

96.8

68.7

10.3

9.1

ADF %

9.9

81.3

56.7

3.3

5.9

Crude fat, %

61.2

 < 0.1

21.1

3.9

1.7

 

Fatty acids, % of total fat

   Palmitic (C16:0)

4.0

3.8

12.0

7.9

   Oleic (C18:1)

77.1

74.9

26.3

16.3

   Linoleic (C18:2)

16.0

18.0

44.2

39.8

   Saturated

6.0

6.2

13.6

10.8

   Unsaturated

93.5

93.6

72.0

61.4

1 Hazelnut kernels, shells, and < 0.4 in whole nuts were 3.88, 9.34, and 6.02% moisture as fed

2 Corn grain was 11% moisture as fed

3 Soybean meal was 10% moisture as fed

Table 2. Growth performance and carcass characteristics of pigs fed 0 or 10% in-shell hazelnuts.

 

Dietary Treatment

 

 

 

Control

Hazelnut

SEM

P-value

Start weight, lb

128.0

128.0

1.6

0.86

End body weight, lb

286.6

284.4

3.1

0.44

Average daily gain, lb/d

2.3

2.3

< 0.1

0.37

Average daily feed intake, lb/d

8.2

8.6

< 0.1

0.36

Feed –to– Gain

3.5

3.8

< 0.1

0.03

Hot carcass weight, lb

216.0

217.0

3.5

0.79

10th rib back fat, in

1.52

1.52

0.1

0.97

Last rib fat depth, in

1.35

1.30

< 0.1

0.41

1 Diets were a common corn-soybean meal diet diluted with either 0% (Control) or 10% (Hazelnut) rolled in-shell hazelnuts

Table 3. Quality characteristics loin chops and fatty acid profile of backfat from pigs fed 0 or 10% in-shell hazelnuts.

 

Dietary Treatment

 

 

 

Control

Hazelnut

SEM

P-value

Color

3.01

3.01

0.04

0.93

pH

5.75

5.78

0.02

0.17

Marbling, %

1.80

1.71

0.09

0.70

Warner-Bratzler Shear Force

3.51

3.51

0.11

0.99

Cook Loss, %

17.00

16.70

0.60

0.75

 

 

 

 

 

Fatty Acid Composition

 

 

 

 

   Myristic acid (C14:0)

1.43

1.37

0.08

0.58

   Palmitic acid (C16:0)

25.60

24.60

0.25

0.01

   Palmitoleic acid (C16:1)

1.92

1.72

0.08

0.07

   Stearic acid (C18:0)

14.30

13.50

0.37

0.14

   Oleic (C18:1)

41.00

43.30

0.47

< 0.01

   Linoleic (C18:2)

8.46

8.89

0.28

0.25

   Linolenic (C18:3)

0.35

0.33

0.01

0.16

   Saturated fatty acids

42.00

39.80

0.55

< 0.01

   Monounsaturated fatty acids

45.40

47.50

0.49

0.01

   Polyunsaturated fatty acids

9.34

9.81

0.29

0.26

1 Diets were a common corn-soybean meal diet diluted with either 0% (Control) or 10% (Hazelnut) rolled in-shell hazelnuts

Table 4.  Ration energy and pig performance of six different rations.

 

Control

Kernel

Shells

In-shell Hazelnuts

% Control Diet

100

90

90

90

80

70

 %Test Ingredient

0

10

10

10

20

30

Predicted ME, kcal/kg

3867

3954

3514

3624

3507

3376

 CP:ME , g:Mcal

38.0

38.9

39.6

38.4

37.4

38.2

Average daily gain, lb/d

2.0

2.0

2.1

2.1

2.0

2.1

Average daily feed intake, lb/d

7.0

6.8

7.3

7.7

7.9

7.5

Gain:Feed

3.5

3.4

3.5

3.7

4.0

3.6

Hot carcass weight, lb

232

227

238

236

236

236

Table 5. Fatty Acid Profile of Pigs Fed Different Hazelnut Rations

 

Control

Kernel

Shells

In-shell Hazelnuts

% Control Diet

100

90

90

90

80

70

 %Test Ingredient

0

10

10

10

20

30

Crude fat, %

2.8

8.2

2.9

4.3

6.3

7.8

CP:ME , g:Mcal

38.0

38.9

39.6

39.2

37.4

32.7

Palmitic (16:0)

25.1

21.7

25.0

23.6

22.2

20.1

Oleic (18:1)

41.3

46.8

41.9

44.1

45.7

48.4

Participation Summary

Educational & Outreach Activities

2 Curricula, factsheets or educational tools
1 Journal articles
1 Published press articles, newsletters
4 Webinars / talks / presentations

Participation Summary:

281 Farmers
19 Ag professionals participated
Education/outreach description:

The project involves three feeding trials: one held during the summer of 2019, one over the early-winter of 2019 and 2020, and one in the summer of 2021.  The first trial and analysis of the trial was completed in time for the 2020 Upper Midwest Hazelnut Growers Conference (March 6-7) and the Midwest Organic Pork Conference March 13 and 14.  Pete Lammers presented the results from the first trial at both conferences.  The results from all the trials were presented at the MOSES Organic Conference in February of 2022 and at the Upper Midwest Hazelnut Growers Conference in March of 2022.

The published materials are now on the Upper Midwest Hazelnut Growers website: http://www.midwesthazelnuts.org/publications.html, under the Technical Reports: Feeding Hazelnuts to Pigs section.

Learning Outcomes

66 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key changes:
  • Per the conference evaluation at the Upper Midwest hazelnut growers conference, farmers reported an increased knowledge of the effect of adding ground-up in-shell hazelnuts to a hog ration.

Project Outcomes

1 New working collaboration
Project outcomes:

The two feeding trials found that a corn/soy ration with a 10% inclusion of ground-up in-shell hazelnuts slightly reduced feed conversion efficiency with the hazelnut-finished pigs needing 6% more feed per unit of gain.  The inclusion of hazelnuts did not change the meat quality attributes, but did change the chemical composition of the fat in the tested pork chops.  Fat from the hazelnut finished pigs had less saturated fat and more unsaturated fat. Oleic acid content was higher in the fat of pigs fed diets containing 10% in-shell hazelnuts as compared to the control diet.

The 2021 trial evaluated different amounts of hazelnut included in the ration and found that even up to 30% replacement growth rates and feed efficiency did not change significantly.  However, the fatty acid profile of the pork did.  The more hazelnut kernel included in the ration the higher the oleic acid levels and the lower he palmitic acid levels. 

Although we were unable to do consumer preference trials due to covid-19, our work suggests that hazelnuts can be fed to pigs to achieve a change in oleic acid.  It will be up to pork producers to determine whether hazelnut-finished pigs can command a market premium.  Developing rations and calculating the value of hazelnuts as a feed for pigs is aided by our relative feed value calculator.

Recommendations:

The hazelnut inclusion did change the fat in the hogs such that it had higher oleic acid.  This means the fat is less solid at room temperature.  This can create problems when processing and cooking the meat.  At the 10% level, the change was not detrimental, but it would be good to conduct further trials to determine the upper limit.  Once covid-19 is done and restrictions are lifted it would be helpful to conduct an actual consumer tasting trial to quantify consumer preference (if any) for hazelnut-finished pork.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.