Relationship between sire tenderness epd and progeny carcass performance




Дата канвертавання19.04.2016
Памер52.46 Kb.
Relationship between sire tenderness EPD and progeny carcass performance
J. Bolsen, J. Minick Bormann, D. W. Moser, T. T. Marston
ABSTRACT: The objectives of this study were to determine how well a bull’s Warner-Bratzler shear force (WBSF) Expected Progeny Difference (EPD) actually predicted his progeny’s carcass performance, and to evaluate the effect of selection for WBSF EPD on other carcass measurements. In 2002, eight Hereford bulls with divergent WBSF EPD were mated randomly to crossbred cows. These EPD were developed from the NCBA Carcass Merit Project, and the accuracies ranged from 0.20 to 0.43. Steers, bulls, and cull heifers that were weaned in two groups were fed out and harvested with complete carcass data collected. Measurements collected on all cattle (n = 98) included dressing percent (DP), hot carcass weight (HCW), ribeye area (REA), 12-13th rib fat thickness (FT), marbling score (MS), kidney pelvic heart fat (KPH), and yield grade (YG). A sub-set of cattle (n = 39) were evaluated for tenderness and sensory traits, including Warner-Bratzler shear force (WBSF), myofibril tenderness (MT), overall tenderness (OT), color (CO), purge loss (PL), juiciness (JU), flavor (FL), and average pH (PH). Data were analyzed using the GLM procedure of SAS. The model for all carcass and sensory traits included fixed effects of weaning group, sex, harvest group, and sire EPD level. Sire WBSF EPD level did not have an effect (P > 0.05) on WBSF, MT, OT, CO, PL, JU, FL, or PH. Low accuracies on the sire EPD and small progeny numbers probably contributed to the lack of difference in tenderness between EPD levels. The regression of actual sire WBSF EPD on progeny WBSF was 0.33 ± 0.44. In the larger data set, DP, HCW, REA, FT, MS, KPH, and YG were unaffected (P > 0.05) by sire WBSF EPD level. These results from a larger sample of progeny indicate that selection on tenderness EPD should not affect other carcass traits.
Introduction
In today's consumer demand driven market economy, livestock producers have to increase the quality of product they are producing. One quality that producers are trying to capitalize on is producing a tender cut of meat, without sacrificing various other traits. In order to do so there has been a push by producers to develop carcass EPD calculations. The purpose of this study was to determine the correlation between a bull’s Warner-Bratzler shear force (WBSF) EPD and his progeny’s actual Warner-Bratzler shear force tenderness. It also looked at how a bull’s WBSF EPD may have affected the progeny’s other carcass data and performance.
Materials and Methods
Bulls were selected with divergent WBSF EPD. Based upon their WBSF EPD, the sires were categorized as either tender or tough (Table 1). The sires were mated randomly to commercial Angus-based cows at the KSU Cow-calf unit.

Offspring were reared in two locations on native range pastures. Calves were then categorized into two weaning types; early weaned and normal weaned. Upon weaning, some bulls were castrated, and some were left intact. Calves were fed out at two locations, and harvested in seven groups. Complete carcass data, including hot carcass weight (HCW), dressing percent (DP), marbling score (MS), ribeye area (REA), kidney-pelvic-heart fat (KPH), yield grade (YG), and 12-13th rib back fat (BF) was collected on 104 head (20 bulls, 54 steers, and 30 heifers). A subset of 40 cattle (20 steers and 20 bulls) were evaluated for WBSF, purge loss, average pH, color, and taste panel traits of myofibril tenderness, juiciness, flavor. For simplicity, these datasets will be referred to as carcass dataset and quality dataset.

Warner-Bratzler shear forces were measured according to Lawrence et al. (2004). Sensory panel analysis included color (visual and L*), myofibril tenderness, juiciness, flavor, and average pH. Color was examined visually, by a panel of trained color judges. Steaks were scored on a scale of one to eight (1 = bleached red, 2 = Very light cherry red, 3 = moderately light red, 4 = bright cherry red, 5 = slight dark red, 6 = moderately dark, 7 = dark red, 8 = very dark red) (Lawrence et al., 2004). The instrumental measurement for L* scores lightness verses darkness, where lower number are darker. An eight point scale was used to evaluate myofibril tenderness, and overall tenderness (1 = extremely tough, 2 = very tough, 3 = moderately tough, 4 = slightly tough, 5 = slightly tender, 6 = moderately tender, 7 = very tender, 8 = extremely tender); juiciness (1 = extremely dry, 2 = very dry, 3 = moderately dry, 4 = slightly dry, 5 = slightly juicy, 6 = moderately juicy, 7 = very juicy, 8 = extremely juicy); and flavor (1 = extremely bland, 2 = very bland, 3 = moderately bland, 4 = slightly bland, 5 = slightly intense, 6 = moderately intense, 7 = very intense, 8 = extremely intense). Steaks were weighed before packaging and after a 14-day aging period. Purge loss was the percentage weight lost by the steaks over that period.

Both data sets were analyzed by the GLM procedure of SAS (SAS, 2000). Fixed effects included weaning category, harvest group (which included feeding location), sex, and sire type (tender or tough). Harvest age was included as a covariate. WBSF was also analyzed by a second model, where individual sire was used as a fixed effect instead of sire type. This model was also used to perform a linear regression of progeny WBSF on sire WBSF EPD.


Results and Discussion
Means, standards deviations, minimums, and maximums for carcass traits and quality traits are shown in Tables 2 and 3. In the carcass dataset, significant fixed effects (P < 0.05) were: weaning category for DP, HCW, BF, KPH, and YG; sex for DP, HCW, REA, and YG; and kill group for DP, HCW, REA, and KPH (Table 4). As expected, bulls had the highest DP and HCW, the largest REA, and lowest YG. Heifers had the lowest DP, lightest HCW, smallest REA, and highest YG. Steers were intermediate to bulls and heifers for the carcass traits. Early weaned calves had higher DP and HCW than conventionally weaned calves. In addition, they exhibited more overall fatness with increased BF and KPH, and higher YG. The covariate of age at harvest was a significant effect (P < 0.05) for YG only. Sire type (tough or tender) did not significantly affect (P > 0.05) any of the carcass traits. However, calves sired by tender EPD sires tended (P < 0.10) to have greater BF than calves sired by tough EPD sires.

In the quality dataset, sex was a significant effect (P < 0.05) for WBSF, color, L*, myofibril tenderness, overall tenderness, and average pH (Table 5). In general, steaks from steers were more tender, lighter colored, and had a lower average pH. The only variable influenced (P < 0.05) by weaning category was color. Early weaned calves had lighter colored steaks than conventionally weaned calves. Sire type was of no significance (P > 0.05) for any trait except purge loss (P = 0.03). Steaks from calves sired by tough sires lost more water than steaks from calves sired by tender sires.

Least squares means by sire for WBSF are shown in Table 6. Sire significantly affected WBSF, however sires did not rank as expected from their EPD. The linear regression of sire EPD on progeny WBSF was 0.33 ± 0.44 (P = 0.4620). This regression would be expected to be 1 if the EPD is doing a good job of predicting progeny performance. These results are probably due to the relatively low accuracies of the EPD and the low numbers of progeny per sire evaluated. The re-ranking of sires explains why there was no difference (P > 0.05) in WBSF between calves sired by tough bulls and calves sired by tender bulls. On a larger number of progeny, sire type did not affect any of the carcass traits. This would indicate that producers can select on WBSF EPD without negatively impacting carcass characteristics.
Implications
In this study, there was no difference in WBSF between calves sired by tender EPD bulls and tough EPD bulls. Low sire accuracy and low progeny number per sire contributed to this result. Producers wishing to improve tenderness in their herds should select sires with higher accuracies as they become available. These results show that selection for WBSF EPD should not cause any unwanted changes in the other carcass traits.
Literature Cited
Lawrence, T.E., M.E. Dikeman, M.C. Hunt, C.L. Kastner, and D.E. Johnson. 2004.

Effects of enhancing beef longissimus with phosphate plus salt, or calcium lactate

plus non-phosphate water binder plus rosemary extract. Meat Science. 67:129-

137.
SAS. 2000. SAS User’s Guide. Cary, NC: SAS Institute, Inc.


Table 1. WBSF EPD and accuracies of sires, and the number of progeny evaluated for carcass traits and quality traits.

Sire

WBSF EPD (kg)

WBSF acc

Carcass n

Quality n

1

-0.48

0.37

19

3

2

-0.27

0.41

10

2

3

-0.26

0.43

7

7

4

-0.15

0.26

8

8

5

0.07

0.28

14

6

6

0.15

0.22

5

5

7

0.15

0.25

20

5

8

0.18

0.20

21

4

Table 2. Means, standards deviations, minimums, and maximums for carcass traits.






n

Mean

Std Dev

Minimum

Maximum

DP (%)

104

63.21

2.50

55.90

68.70

HCW (kg)

104

329

41

237

441

REA (cm2)

99

83.9

9.7

67.1

113.5

BF (cm)

91

1.17

0.41

0.41

2.54

KPH (%)

99

2.3

0.5

1.5

3.5

YG

89

2.93

0.63

1.34

4.41

MS

104

516

87

390

800

Table 3. Means, standards deviations, minimums, and maximums for quality traits.






n

Mean

Std. Dev.

Minimum

Maximum

Color

40

4.4

1.54

2.04

7.54

Purge loss (%)

40

0.0125

0.0168

0.0067

0.1124

L*

40

42.70

3.95

31.35

48.36

WBSF (kg)

40

5.05

1.38

2.74

9.51

Myofibril tenderness

39

5.47

0.93

3.58

7.50

Juiciness

39

5.71

0.45

4.67

6.50

Flavor

39

5.75

0.36

4.75

6.42

Overall tenderness

39

5.65

0.93

3.67

7.50

Average pH

39

5.78

0.31

5.44

6.66

Table 4. LS Means by sex and wean type for carcass traits.






Sex

Wean type




Bulls

Heifers

Steers

P

Early

Normal

P

DP (%)

65.47

63.17

64.21

0.0142

65.17

63.40

0.0002

HCW (kg)

362

290

354

0.0003

345

325

0.0116

REA (cm2)

92.4

77.1

87.1

0.0143

NS

NS




BF (cm)

NS

NS

NS




1.24

0.91

0.0059

KPH (%)

NS

NS

NS




2.45

2.18

0.0257

YG

2.38

3.32

2.94

0.0079

3.12

2.64

0.0089

Table 5. LS Means by sex for quality traits.






Bull

Steer

P

WBSF (kg)

5.64

4.45

0.0048

Color

5.47

3.28

0.0001

L*

41.28

44.12

0.0213

Myofibril tenderness

5.61

5.81

0.0414

Overall tenderness

5.31

6.07

0.0267

Average pH

5.93

5.70

0.0274

Table 6. Progeny WBSF LS means by sire.



Sire

n

Progeny WBSF LS mean (kg)

6

5

3.88a

8

4

4.34a

1

3

4.48a

4

8

4.60a

3

7

5.07ab

2

2

5.21abc

7

5

6.09bc

5

6

6.41bc

a Means in the same column with a different superscript are different (P < 0.05)


База данных защищена авторским правом ©shkola.of.by 2016
звярнуцца да адміністрацыі

    Галоўная старонка