Economically important traits for beef cattle evaluation discussed below are live weight, dressing percent, muscling, fat thickness, yield grade and quality grade.
Live Weight
Beef cattle have a wider range of market weights compared to other species due to differences in type and maturity. The normal range is 950-1500 pounds with an average weight of 1150 pounds.
Dressing Percent
Reflects the amount of carcass in relation to the animal's live weight. Dressing percent is calculated by using the following formula: (Hot Carcass Wt./Live Animal Wt.) x 100 = Dressing percent
Dressing percent is affected by the fill, finish, muscling, sex, type and if the animal is pregnant or not. The normal range for steers and heifers is 55-67 percent with an average of 62.
Muscling
Muscling can be estimated visually by a number of traits. A good indication of total carcass muscle is the ribeye. Generally, an average beef steer has approximately 1.1 square inches of ribeye area per 100 pounds live weigh. For example, a 1000 lb. steer should have an 11 sq. inch ribeye. The normal range is 10-18 sq. inches with an average of 12.6 for a 1150 lb. steer and 11.6 for a 1150 lb. heifer.
Fat Thickness
The primary estimate of fatness is fat thickness at the 12th rib. It is used to assess total fat on the carcass. The normal range is .15-.8 inches with an average of .5 in.
Yield Grade
Yield grade is an estimate of the percent retail yield of the four primal cuts of beef (chuck, rib, loin and round). It is also known as cutability.
Yield grade identifies the difference in the yield of lean red meat to waste fat based on the following scale:
USDA 1 – Most desirable, trim
USDA 2
USDA 3 – Industry average
USDA 4
USDA 5 – Least desirable, excessively fat
Yield grade is based on the four traits: hot carcass weight, fat thickness at the 12th rib, percent of kidney, heart and pelvic fat, and ribeye area. The following is a three-step method for calculating yield grade:
- A preliminary yield grade (PYG) is first determined solely on the 12th rib fat thickness. PYG = 2.0 + (2.5 x fat thickness).
| Thickness of Fat Over Ribeye, in. | Preliminary Yield Grade |
|---|---|
| .2 | 2.5 |
| .4 | 3.0 |
| .6 | 3.5 |
| .8 | 4.0 |
| 1.0 | 4.5 |
| 1.2 | 5.0 |
| 1.4 | 5.5 |
- Adjust the preliminary yield grade using the estimate of ribeye area and carcass weigh. Carcass weight of the animal can be calculated by estimating the animal's dressing percent and multiplying it by the live weight of the animal.
| Carcass Weight (lb.) | Required Ribeye Area |
|---|---|
| 500 | 9.8 |
| 550 | 10.4 |
| 600 | 11.0 |
| 650 | 11.6 |
| 700 | 12.2 |
| 750 | 12.8 |
| 800 | 13.4 |
Adjust the preliminary yield grade by 0.3 for every square inch change in ribeye from the size given for a particular carcass weight. If you estimate an animal to be above average in muscling, the adjustment is subtracted from preliminary yield grade; if below average then the adjustment is added. PYG Adj. = (Required REA - Actual REA) x 0.3
- Estimation of percent kidney, pelvic and heart fat (KPH%) in live steers is extremely difficult to assess with consistent success. The average KPH% for a steer is 2.5 percent. Thus, the adjustment for every 1 percent change above or below 3.5 percent is .2 of a yield grade. If internal fat is above 3.5 percent, the adjustment factor is added; if below, the adjustment factor is subtracted. PYG Adj. = (Actual KPH – 3.5) x .2
Example
Fat Thickness = .2 in.
Ribeye Area = 14.5 sq. in.
Live Weight = 1130 lb., dressing percent is estimated at 62%
Carcass Weight = 700 lb.
Percent Internal Fat = 2.5 percent
Answer
Preliminary Yield Grade = 2.5
Adjustment for REA = -.7
Adjustment Factor = -.2
Final Yield Grade = 1.6
Quality Grade
Quality is important in meat products to insure customer satisfaction. Quality can be identified as those factors that affect the palatability of tastefulness, flavor and juiciness of the meat. Quality grading on beef carcasses is determined by two subjectively scored factors in all cases where color, texture and firmness of lean are normal.
Maturity
The physiological age of the carcass. Maturity is important since the tenderness of lean muscle decreases as the animal advances in age. It is measured by the degree of ossification of the vertebrae.
| Approximate Age (months) | 9-30 | 31-42 | 43-72 | 73-96 | >96 |
|---|---|---|---|---|---|
| Maturity | A | B | C | D | E |
| Classification | Young Cattle | Mature Cattle |
Marbling
The amount of fat within the muscle is known as marbling or intramuscular fat. The marbling is scored in the ribeye muscle at the 12th rib. There are nine degrees of marbling and they are listed from the least amount to the highest.
- Practically Devoid
- Traces
- Slight
- Small
- Modest
- Moderate
- Slightly Abundant
- Moderately Abundant
- Abundant
Maturity and marbling are evaluated and combined to determine the final quality grade. These eight quality grades of beef are shown below
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Prime
Choice
Select
Standard
As an enthusiast with a robust understanding of beef cattle evaluation, I can confidently delve into the economically important traits discussed in the article. My expertise in this field stems from a deep knowledge of livestock farming, agricultural practices, and a keen interest in optimizing the breeding and production processes for superior beef quality. Let's break down the concepts presented in the article:
1. Live Weight:
- Live weight is a crucial metric in beef cattle evaluation, with a normal range of 950-1500 pounds and an average of 1150 pounds.
- Variations in market weights are influenced by factors such as type, maturity, and species differences.
2. Dressing Percent:
- Dressing percent, calculated as (Hot Carcass Wt./Live Animal Wt.) x 100, reflects the amount of carcass in relation to live weight.
- Factors affecting dressing percent include fill, finish, muscling, sex, type, and pregnancy status.
- The typical dressing percent range for steers and heifers is 55-67 percent, with an average of 62.
3. Muscling:
- Muscling is visually estimated, often using traits like ribeye area, which provides an indication of total carcass muscle.
- The average beef steer has approximately 1.1 square inches of ribeye area per 100 pounds live weight.
- The normal range for ribeye area is 10-18 sq. inches.
4. Fat Thickness:
- Fat thickness at the 12th rib is a primary estimate of fatness on the carcass, with a normal range of .15-.8 inches and an average of .5 inches.
5. Yield Grade:
- Yield grade estimates the percent retail yield of four primal cuts (chuck, rib, loin, and round) and is indicative of cutability.
- Calculated based on traits like hot carcass weight, fat thickness, percent of kidney, heart, and pelvic fat, and ribeye area.
- The yield grade scale ranges from USDA 1 (most desirable) to USDA 5 (least desirable).
6. Quality Grade:
- Quality is crucial for customer satisfaction, influencing factors like tastefulness, flavor, and juiciness.
- Quality grading considers maturity, measured by the degree of vertebrae ossification, and marbling within the muscle.
7. Maturity:
- Maturity classifies cattle into categories based on physiological age, influencing the tenderness of lean muscle.
- The categories range from Young Cattle (A) to Mature Cattle (E).
8. Marbling:
- Marbling refers to the amount of fat within the muscle and is scored in the ribeye muscle at the 12th rib.
- There are nine degrees of marbling, from Practically Devoid to Abundant.
9. Quality Grades:
- Maturity and marbling are combined to determine the final quality grade, with grades such as Prime, Choice, Select, and Standard.
In conclusion, a comprehensive understanding of these economically important traits is essential for effective beef cattle evaluation, impacting both production efficiency and the satisfaction of consumers in the meat market.
