Effect of Processing Flax in Feedlot Diets on Beef Heifer Performance, Carcass Composition, and Trained Sensory Panel Evaluations

Travis Maddock, Vern Anderson, Rob Maddock, Marc Bauer and Greg Lardy

 


T

his study was designed to investigate if processing flax would affect how cattle responded to flax inclusion in the diet. These data suggest flax addition increases gain and feed efficiency, and that processing flax is necessary to optimize feedlot performance.

 

A randomized complete block design was used to evaluate the effects of processing flax in beef feedlot diets. One hundred twenty-eight beef heifers (792.8 31.0 lbs initial BW) were blocked by weight and assigned randomly to 16 pens (8 heifers/pen). Pens were then assigned to one of four diets. Heifers were fed a growing diet for the first 56 days after which they were stepped up to a finishing ration (Table 1). The control growing diet consisted of corn, corn silage, alfalfa, barley malt pellets and linseed meal, and the finishing diet consisted of corn, corn silage, alfalfa, and linseed meal. Flax diets added whole, rolled, or ground flax to rations at eight percent of DM, replacing linseed meal and partially replacing corn. Supplements were formulated to provide 0.5 mg MGA, 2000 IU vitamin E, and 232 mg monensin daily. Heifers were harvested by block on days 96, 97, and 124 (two blocks) with carcass data and m. longissimus lumborum samples for shear force and sensory panel analysis collected. Dry matter intake (25.2 0.4 lbs/d) was not affected (P = 0.79) by treatment. Flax addition increased (P ≤ 0.01) ADG (lbs/d), feed efficiency (feed:gain), and hot carcass weight (lb; HCW), and increased KPH fat percent, and calculated yield grade. Processing (grinding or rolling) increased (P ≤ 0.001) ADG, feed efficiency, and HCW. No treatment effects (P ≥ 0.23) were noted for dressing percent, external fat, or ribeye area. Marbling score tended to increase with flax addition (P = 0.14). Steaks from cattle fed flax were less juicy (P = 0.06) than those from control diets, and steaks from cattle fed rolled flax were juicier (P = 0.09) than those fed ground flax. Treatment did not affect (P ≥ 0.16) sensory tenderness or flavor ratings. Warner-Bratzler shear force tenderness was affected (P = 0.06) by treatment, with steaks from cattle fed flax rated more tender (P = 0.04) than the control cattle, and steaks from cattle fed processed flax were more tender (P = 0.05) than steaks from cattle fed whole flax. These data indicate including flax at eight percent of diet DM improves growth and efficiency of feedlot heifers, but may increase internal fat deposition and negatively affect yield grade. Additionally, processing flax is necessary to optimize these effects. Feeding flax reduced sensory panel ratings of beef juiciness, however flax did increase mechanical measurements of tenderness in the resultant beef.


 

Table 1. Diet composition of control and flax diets.

 

 

 

 

 

Growing Dietsa

 

Finishing Dietsa

Ingredient

Control

Flax

 

Control

Flax

 

------- 100% DM Basis ------

Flax

--

8.00

 

--

8.00

Corn

31.00

27.00

 

79.00

75.75

Corn Silage

30.00

30.00

 

7.00

7.00

Alfalfa

14.00

14.00

 

7.00

7.00

Barley Malt Pellets

18.00

18.00

 

--

--

Linseed Meal

4.00

--

 

4.75

--

Supplementb

3.00

3.00

 

2.25

2.25

a Composition of flax diets was the same regardless of degree of processing.

b Supplements were formulated to provide 0.5 mg melengesterol acetate (MGA),

2000 IU vitamin E, and 232 mg monensin daily.

 


Table 2. Effects of processing flax on feedlot performance and carcass characteristics.

 

 

Dietsa

 

P-valuesb

 

Item

Control

Whole

Rolled

Ground

SE

Treatment

Control

vs. Flax

Whole vs.

Processed

Rolled vs. Ground

 

DMI, lbs/d

25.6

25.0

25.1

25.1

0.4

0.79

0.34

0.90

0.96

 

ADG, lbs/d

3.08

3.18

3.42

3.41

0.08

0.01

0.008

0.01

0.64

 

Feed Efficiency

8.25

7.84

7.33

7.34

0.31

<0.001

0.001

0.008

0.68

 

HCW, lbs

702.2

716.2

729.5

726.8

5.4

0.001

<0.001

0.008

0.38

 

Dressing %

60.4

60.8

60.6

60.8

0.5

0.85

0.48

0.79

0.70

 

Backfat, in

0.49

0.52

0.55

0.53

0.03

0.33

0.14

0.42

0.45

 

REA, in2

12.2

11.9

11.7

12.1

0.2

0.23

0.26

0.79

0.09

 

KPH, %

2.20

2.55

2.54

2.58

0.10

0.07

0.01

0.92

0.79

 

Yield Grade

2.93

3.20

3.40

3.21

0.09

0.03

0.01

0.38

0.17

 

Marblingc

431.6

477.5

469.8

456.2

13.1

0.14

0.04

0.39

0.48

a Control treatment was a basal, no-flax diet; whole, rolled, and ground treatments included flax in the diet at 8% of DM.

b P-values are associated with F-test for treatment and contrasts of control diets vs. diets that include flax, whole flax diet vs. treatments where flax was processed, and the rolled flax diet vs. the ground flax diet.

c Marbling scores are reported as 300 = slight 0 or low select, 400 = small 0 or low choice, and 500 = modest 0 or average choice.

 

 

Table 3. Effect of processing flax on sensory panel evaluations and Warner-Braetzler shear force determination of tenderness.

 

 

 

 

 

Dietsa

 

P-valuesb

Item

Control

Whole

Rolled

Ground

SE

Treatment

Control

vs Flax

Whole vs

Processed

Rolled vs Ground

Tendernessc

5.08

5.21

5.46

5.24

0.12

0.16

0.11

0.31

0.18

Juicinessc

5.54

5.19

5.50

5.27

0.10

0.02

0.06

0.09

0.09

Flavorc

5.29

5.23

5.44

5.41

0.09

0.30

0.54

0.07

0.82

Shear, lbs

8.15

7.91

7.01

7.29

0.33

0.06

0.04

0.05

0.49

a Control treatment was a basal, no-flax diet; whole, rolled, and ground treatments included flax in the diet at 8% of DM.

b P-values are associated with F-test for treatment and contrasts of control diets vs. diets that include flax, whole flax diet vs. treatments where flax was processed, and the rolled flax diet vs. the ground flax diet.

c Tenderness, juiciness, and flavor were evaluated on a scale of 1 to 8 with anchors of 1 = not at all tender, not at all juicy, no flavor at all and 8 = extremely tender, extremely juicy, and an extreme amount of flavor.

 

 


Implications

These results suggest that flax incorporated into the diet at eight percent of dry matter will increase average daily gain and feed efficiency and that processing of the flax is necessary to optimize these effects. Additionally, adding flax to feedlot diets can increase internal fat deposition and increase yield grades while tending to increase carcass quality grades. Palatability of beef may be affected by flax, as trained sensory panelists reported lower juiciness scores from flax-fed beef, however mechanical determination of beef tenderness indicated that feeding flax may increase tenderness.