Maternal energy status affects meat quality

Maternal energy status affects meat quality

IN many places in the U.S., cows graze pastures as the primary source of nutrients during gestation, and in the upper Great Plains region, beef cattle producers implement low-cost feeding programs during mid-gestation wherein cows typically graze dormant forage or other poor-quality forages, potentially causing a deficiency in both protein and energy if cows are not supplemented, according to South Dakota State University animal scientists.

In the "2013 South Dakota Beef Report," D.A. Mohrhauser, A.R. Taylor, K.R. Underwood, R.H. Pritchard, A.E. Wertz-Lutz (presently at ADM Alliance Nutrition Inc.) and A.D. Weaver wrote that, as a result, this could cause the fetus to receive inadequate nutrients, potentially altering fetal development and, ultimately, the body composition of the offspring.

Research has suggested that maternal under-nutrition during pregnancy may result in the offspring developing a "thrifty phenotype" that is more prepared to deal with sparse nutrient availability. Thus, maternal nutrition has the potential to affect the development of muscle and adipose tissue in the offspring, Mohrhauser et al. said.

They conducted a study to determine the influence of maternal energy status during mid-gestation on the carcass characteristics and meat quality of the offspring. To alter maternal energy status, they said cows either grazed pasture or were fed in a drylot at 80% of the energy requirements for bodyweight maintenance during a mean period of 109-207 days of gestation.

Changes in body condition score (BCS), bodyweight, rib-eye area (REA) and 12th-rib back fat were measured throughout mid-gestation and were used to determine cow energy status — positive (PES) or negative (NES).

Cows in the NES group had a significantly greater reduction in BCS, bodyweight, REA and 12th-rib back fat during mid-gestation (Table 1), the researchers said. However, maternal energy status did not influence the offspring's hot carcass weight, dressing percent, REA, percent kidney, pelvic and heart fat (KPH), marbling score, percent intramuscular fat, objective color or Warner-Bratzler shear force (Table 2).

Mohrhauser et al. pointed out that there was a tendency for NES calves to have improvements in 12th-rib back fat and U.S. Department of Agriculture yield grade.

Calves from NES cows had a greater M-Ratio and I-Ratio — calculations used to compare the ratio of marbling (M-Ratio) and percent intramuscular fat (I-Ratio) with 12th-rib back fat.

These results suggest that maternal energy status during mid-gestation may affect fat deposition in intramuscular and subcutaneous fat depots without affecting muscle mass, Mohrhauser et al. concluded.

Marbling development. Also in the "2013 South Dakota Beef Report," S.A. Kern, R.H. Pritchard, S.M. Scramlin, B.P. Holland (presently at Merck Animal Health), A.D. Blair and K.R. Underwood discussed the influence of growth stage on carcass development and factors associated with marbling development in beef cattle.

Kern et al. suggested that there are many cellular regulatory factors that ultimately determine the intramuscular fat, or marbling content, and quality of beef carcasses.

Identifying factors that play a critical role in the development of intramuscular fat throughout the feeding period, as well as determining how cattle feeders can manipulate these factors, will be crucial for continuing to improve beef quality, they said.

Postnatal adipose tissue development was previously thought to occur in the following order: internal, intermuscular, subcutaneous and intramuscular. Yet, Kern et al. pointed out that this has been contested by recent studies suggesting that postnatal adipose tissue deposition occurs simultaneously among these depots during growth and that marbling is not a late-developing tissue, as previously believed.

A better understanding of how and what causes marbling to develop throughout the finishing phase is required to continue to improve this economically important trait.

Previous marbling research in cattle has explored the effect of various enzymes and transcription factors and how their expression or presence affects marbling, Kern et al. said. However, many of the factors identified were only measured near the end of the feeding phase, so there is still a lack of knowledge as to how these factors change throughout the finishing phase.

Therefore, they hypothesized that marbling is an early-developing tissue and that cellular factors influencing marbling development are growth stage dependent. They conducted a study to determine whether cellular factors associated with marbling development change with growth stage throughout the feeding period and whether they are related to marbling relative to carcass composition.

Kern et al. said their results (Table 3) are novel as they show not only what cellular factors play a role in marbling development but also how their expression and presence change as an animal grows in an American-style production system.

The increase in both expression and presence of peroxisome proliferator-activated receptor-gamma at the end of the feeding phase (data not shown) suggests that the proliferation and differentiation of additional cells to adipocytes is required in order to increase intramuscular fat content, Kern et al. said.

This does not mean that adipocyte filling (lipogenesis) does not play a key role as well, they explained, but marbling content will reach a plateau without the recruitment of additional adipocytes.

While it has been previously established that intramuscular adipocytes have a pattern of metabolism unique from other adipocytes, further research into how the metabolism of intramuscular fat differs from other fat depots and how this metabolism changes throughout the feeding phase will enhance the ability to produce high-quality carcasses while limiting undesirable carcass fat, Kern et al. concluded.

The full research reports can be found at www.sdstate.edu/ars/species/beef/beef-reports/2013beefreport.cfm.

 

Outsmart stress

Stressful situations are practically unavoidable for modern beef cattle. With stress often comes reduced performance or even the opportunity for disease to take hold and cause more significant losses.

"A calf that's eating goes a long way to increasing performance and weight gain, and, along with that, there's improved health in these calves," said Dr. Kerry Barling, global manager of beef technology at Lallemand Animal Nutrition. "For years, we've talked about respiratory disease in cattle being a major problem. Usually, respiratory disease manifests itself through stress, which weakens the calf's system and allows disease to take place."

The bovine respiratory disease complex (BRDC) is the most common cause for cattle deaths and results in more than $650 million in losses industry-wide. The average pull rate in feedlot cattle has remained at around 30% for years, even with advances in vaccines and antibiotics to tackle both viral and bacterial causes of BRDC, Barling noted.

"The one thing we haven't been as diligent in is addressing how we alleviate that stress through management," he said. "Another area the industry can pursue further is how to prime the calf's immune system to help offset the effects of stress even before it occurs."

One way to help outsmart stress before its effects on cattle are realized is to add a direct-fed microbial, such as Saccharomyces cerevisiae boulardii, which has been shown to improve cattle feed uptake, lower morbidity and lower mortality. In a trial where all cattle were given an injectable antibiotic upon arrival, animals fed S. cerevisiae boulardii strain I-1079 (ProTernative) had reduced pulls compared with controls.

Careful management during stressful situations — plus adding a probiotic to help reduce the negative impact of stress in cattle — can help the industry confront BRDC like never before.

"Particularly in this current economic market where we're talking about $1,500 calves, the investment makes sense," Barling said. "It's a simple, cost-effective way to manage your risk. For just a few dollars per head, adding a probiotic can reduce treatment for (BRDC) by half and even reduce mortality."

 

1. Least squares means for days of gestation at mid-gestation and cow BCS, bodyweight, REA and fat thickness at the beginning and end of the mid-gestation treatment period

 

-Cow energy status-

 

-P-value-

Trait

Positive

Negative

SEM*

Status

Block

Days of gestation

84

84

1.3

0.9730

0.0215

Initial BCS

4.78

4.94

0.051

0.1028

0.0076

Final BCS

4.92

4.29

0.046

0.0001

0.0128

Change in BCS

0.14

-0.65

0.050

<0.0001

0.4076

Initial bodyweight, lb.

1,017

1,017

5.2

0.9907

<0.0001

Final bodyweight, lb.

1,126

967

6.7

<0.0001

<0.0001

Change in bodyweight, lb.

109

-50

5.6

<0.0001

0.3197

Initial REA, sq. in.

8.85

9.24

0.146

0.1035

0.0007

Final REA, sq. in.

9.38

8.25

0.155

0.0003

0.0004

Change in REA, sq. in.

0.53

-0.99

0.111

<0.0001

0.4460

Initial 12th-rib fat thickness, in.

0.15

0.16

0.005

0.7228

0.0081

Final 12th-rib fat thickness, in.

0.16

0.14

0.004

0.0251

0.0418

Change in 12th-rib fat thickness, in.

0.01

-0.02

0.004

0.0083

0.2907

Energy status

2.09

-2.32

0.146

<0.0001

0.9888

*SEM = standard error of means.

 

2. Carcass characteristics of calves from dams in a positive or negative energy status during mid-gestation

 

-Cow energy status-

-Gender-

-P-value-

Trait

Positive

Negative

SEM

Heifers

Steers

SEM

Status

Gender

SxG

Hot carcass weight, lb.a

728

714

8.9

682

761

9.0

0.2373

<0.0001

0.7968

Dressing %a,d

63.12

62.97

0.194

63.23

62.86

0.196

0.5500

0.1563

0.3510

12th-rib back fat, in.b

0.49

0.44

0.018

0.50

0.43

0.018

0.0585

0.0084

0.8652

REA, sq. in.b

13.00

13.10

0.172

12.78

13.32

0.172

0.6839

0.0205

0.5890

KPH, %b

2.09

2.10

0.029

2.25

1.94

0.029

0.8722

<0.0001

0.9601

USDA yield gradeb

2.86

2.64

0.084

2.82

2.69

0.084

0.0502

0.2635

0.8688

Marbling scoreb,e

430

440

8.6

451

418

8.6

0.3857

0.0053

0.8287

M-Ratiob

-0.24

0.29

0.178

0.04

0.01

0.178

0.0275

0.8888

0.7563

Intramuscular fat, %c

4.09

4.46

0.184

4.58

3.97

0.181

0.1332

0.0136

0.1673

I-Ratioc

-0.32

0.33

0.167

-0.02

0.04

0.164

0.0044

0.7956

0.2568

aPositive: n = 59; negative: n = 48; heifers: n = 60; steers: n = 47.

bPositive: n = 59; negative: n = 47; heifers: n = 59; steers: n = 47.

cPositive: n = 57; negative: n = 44; heifers: n = 55; steers: n = 46.

dCalculated using final live bodyweight with 4% shrink.

e300 = Slight00; 400 = Small00.

 

3. Carcass data and estimated carcass composition by growth stagea

 

-Growth stage-

 

-Significance of contrasts-

 

Early feeding

Mid-feeding

Late feeding

SEM

Linear

Quadratic

Liveweight, lb.

750

1,023

1,303

14.24

<0.0001

<0.0001

Hot carcass weight, lb.

417

609

810

7.25

<0.0001

<0.0001

Dressing %

55.56

59.65

62.19

0.52

<0.0001

<0.0001

REA, sq. in.

9.1

10.3

13.0

0.34

<0.0001

0.0227

12th-rib fat thickness, in.

0.11

0.29

0.46

0.04

<0.0001

0.0075

Adjusted fat thickness, in.

0.10

0.32

0.48

0.04

<0.0001

0.0007

KPH, %

2.10

2.37

2.88

0.18

0.0070

0.2944

USDA yield grade

1.88

2.85

3.26

0.13

<0.0001

<0.0001

Marbling scoreb

282

322

427

16.57

<0.0001

0.1084

Intramuscular fat, %

1.85

3.53

5.40

0.27

<0.0001

0.0005

M-ratio

0.17

-0.32

0.15

0.30

0.9684

0.2620

Edible portion, %

83.53

85.26

86.49

0.36

<0.0001

0.0042

Water, %

52.06

48.47

44.89

0.63

<0.0001

0.0011

Fat, %

15.97

22.13

27.72

0.88

<0.0001

0.0002

Protein, %

14.43

13.75

13.22

0.18

0.0003

0.0180

Ash, %

0.85

0.75

0.66

0.02

<0.0001

0.0021

Bone, %

16.47

13.75

13.22

0.36

<0.0001

0.0042

aLeast square means.

bMarbling score: 200=Traces0, 300=Slight0, 400=Small0, 500=Modest0.

 

Volume:86 Issue:24

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