Beef Cattle Live Animal Assessments

3.6 Live animal assessments

Assessment of muscularity

Linear scoring is a technique which allows a systematic description of an animal’s morphology. Linear scoring reveals part of the animal’s economic value and, if the scored traits are heritable, part of its genetic value. Economic and environmental conditions vary over time and between countries so the economic importance of each scored trait may differ depending on the circumstances. The specific relative importance has to be determined by the responsible breeding organisations.

As well as the description of a single animal, data from linear scorings are used for genetic evaluation of dairy, dual purpose and specialised beef breeds.

Many breeders, breed societies and those in the AI industry use linear scoring in routinely performed animal recording. In beef breeds linear scoring of muscle shape is particularly important as an indicator of saleable beef yield per animal, and thus is an indispensable part of the beef recording system.

To meet the need for an efficient world wide, genetic exchange, international comparison of breeds, and demand for more comparability of individual cattle between countries, procedures for linear scoring of muscularity should be harmonised. This need is best served by an internationally recognised set of recommendations.

The following recommendation may help organisations design a linear scoring system for beef performance recording which suits their market conditions, and which may lead to more homogeneous and comparable scores between different countries.

The present recommendation refers only to linear scoring of muscularity, which is usually part of a complete integrated scoring system within breed. It does not deal with the full spectrum of linear scoring. A complete linear scoring system for a given breed often includes further items such as skeletal traits, udder, legs etc.

The following recommendation may be used both for dual-purpose breeds as well as for specialised beef breeds. Linear scoring can be conducted on any category of animals, such as male and female calves, heifers, cows, bulls and steers.

Recommended approach to be taken in organising Linear Scoring

Linear scoring has the following characteristics:

Linear scoring has the following characteristics:

1. Linear scoring is a systematic description of an animal’s morphology.
2. It is usual for a linear scoring scheme to takes several anatomical sites into account.
3. The anatomical sites must be precisely defined.
4. Within one single anatomical site, linear scoring provides a description of the biological extremes and a number of intermediates.
5. The scores represent an ordinal scale, which should allow for sufficient discrimination in the degree of expression of the linear trait.
6. The extremes and the intermediates are ordered according to the degree of expression of the trait. For example, thin and thick, long and short etc.
7. A high or a low score has no particular meaning and it is not necessarily desirable or undesirable.
8. By convention one of the extremes receives the score ‘1’; the other levels receive a number in ascending order which describes the expression of the trait.
9. A scale from 1-9 points is recommended for most traits.
10. Where the range of biological extremes is large in the population of animals under consideration, (e.g. double muscling or an across breed recording scheme) the scale may need to be extended. A 1 to 15-point scale is recommended in such circumstances.
11. The scoring system should be consistent across contemporary groups, i.e. breeds/breed groups.
12. Linear scoring should if possible be conducted on animals which belong to the same category in terms of sex and age.
13. For each category of animals, the scoring scale for muscle shape should be the same.
14. Scoring for muscularity relates to muscle shape only.

The traits which should, as a minimum, be taken into account in a muscularity linear scoring scheme are:

1. Shoulder width.
2. Loin width.
3. Rump length.
4. Rump width.
5. Thighs width.
6. Thighs depth.
7. Thighs inside.
8. Thighs rounding.

The following is a graphical representation of the linear muscular anatomical sites.

a) Shoulder width

b) Loin width

c) Rump length File:3.6.1 c.jpg

d) Rump width

e) Thighs width

f) Thighs depth

g) Thighs inside

h) Thighs rounding .

3.6.3 Requirements for linear scoring

All factors accounting for any non-genetic variance should be recorded., e. g.

1. Scorer’s identification.
2. Scoring date/time.
3. Management group.
4. Nutritional status etc.

All information should be recorded in accordance with ICAR recommendations where they apply.

Within contemporary group (e.g. animals of one scoring season within farm) all animals of the same category should be scored according to the standard of the appropriate category.

In order to prevent any pre-adjustments by the scorer, it is necessary that no information other than the animal’s identification should be provided when scoring. No other information, particularly in relation to the ancestors of the animal, or its age should be available.

Linear scoring requires well trained technicians. The practical and theoretical knowledge of the scorer should be tested after receiving appropriate training. The training should allow the scorer to:

1. Make full use of the scale within the category of animals being recorded.
2. Attain a minimum level of repeatability within scorer.
3. Attain a minimum level of repeatability across scorer.

If possible, a routine regional rotation of the scorers is recommended as this facilitates and improves the statistical evaluation of data from linear scoring in different herds by giving a better estimation of the scorer’s effect.

The responsible breeding organisation should establish a routine supervision procedure for the scorers. The competency of all scorers should be monitored and training should be provided annually or more often if necessary.

Assessment of body condition

Condition scoring can be defined as an objective attempt to describe the body condition or degree of fatness of cattle by visual assessment. By adjusting the plane of nutrition, body condition can, to a large extent be controlled.

Purpose

Condition scoring provides a means of attaining the desired target condition scores for optimum production and reproduction, whilst simultaneously making optimum use of available feed sources.

Differences in condition can also be recorded within contemporary groups as a means of quantifying differences among animals or for consideration in models for genetic evaluations.

Recommended methods

Different scoring systems have been developed through the years. For example, one such system has been developed by the East of Scotland College of Agriculture in 1973. In this instance, the score range between 1 (extremely thin) and 5 (extremely fat) with half scores sometimes used between the main scores.

The method recommended is based on the nine-point system developed for zebu cattle by Nicholson and Butterworth (1985) or similar systems. A nine-point system gives distinguishable steps that can be described and used to account for the wide range of body conditions that are shown by cattle from temperate to tropical areas. It avoids the use of half-points, which can be common when applying a five-point system. An arrangement in which three main categories are first defined, and which are then each sub-divided into three to give nine possible options gave repeatable results as well as being easy to teach and explain to others. Units of three worked well where subjective assessment was required. There is always one unit at each end and one in the middle, making decisions easier.

How to condition score

Condition scoring is primarily concerned with two specific areas in assessing fat cover (Figure 3.1). The first is the loin area (between the hip bone and the last rib) which incorporates the spinous and transverse processes of the lumbar vertebrae. The area surrounding the tail head and pin bones is the second.

Figure 3.1. Areas on the body where fat cover is assessed for body condition scoring.

The fat cover over the loin area (transverse and spinous processes) is the most important scoring area since changes in fat deposition can be clearly felt and assessed particularly in thinner animals (Scores 1 to 5 on the 9-point scale). The deposition of fat in cattle with a score greater than 5 is such that the transverse processes become increasingly difficult to feel. Fat deposition over the pin bones and the surrounding tail head area becomes increasingly excessive in cows with scores of 7, 8 and 9. The difference between a score of 6 and 7 is the actual deposition of fat on either side of the tail-head which must be clearly visible. Ideally, the weighing of animals and condition scoring should be carried out simultaneously so that the relevant assessing areas can be felt. Continuous practicing in condition scoring of cattle will increase the accuracy of assessment and the speed at which it is carried out by the operator.
Table 3.2. Description of the body condition scores for cattle on a scale from 1 to 9.

Score	Description
1	Very thin (Emaciated)	Animal markedly emaciated; bone structure easily seen over body; little muscle present; animal weak, lethargic.
2	Thin	Animal emaciated; individual spinous processes, ribs, hooks (tuber coxae), pins (tuber ischii), shoulder blades and spine all prominent, sharply defined; some muscle development; neck thin; prominent withers; shoulders sharply angular. Area around the tail-head completely sunken.
3	Less thin	Vertebral column prominent and individual spinous processes can be felt; little fat, but superspinous muscle over spinous processes apparent; ribs, pins, (tuber ischii) and hooks (tuber coxae) prominent; loin area and rump concave; little muscle or fat covering over withers and shoulders.
4	Less than moderate	Vertebral column prominent and individual spinous processes can be felt; little fat, but superspinous muscle over spinous processes apparent; ribs, pins, (tuber ischii) and hooks (tuber coxae) prominent; loin area and rump concave; little muscle or fat covering over withers and shoulders.
5	Moderate	Superspinous muscles developed and readily apparent; vertebral column can be felt; hooks (tuber coxae) rounded; rump rounded, convex; pins (tuber ischii) not visible; some fat can be felt in shoulder area region and at base of neck; can feel ribs, but not visible.
6	More than moderate	Cannot feel spinous processes easily; back becoming flat well covered; rump convex and well muscled; some fat can be felt on neck, base of neck and shoulder area; neck filled into shoulder; hooks (tuber coxae) just visible.

The following series of illustrations can serve as a guide in scoring cattle for condition (Figure 3.2).
Figure 3.2. Illustration of body condition scores.

Condition scoring does not eliminate the need for weighing animals. Ideally these two operations should be carried out simultaneously. Condition scores should not be affected by weight, age or breed. More accurate alternatives exist to compare differences in animals for body condition, such as subcutanious fat thickness measurements by using Real Time Ultrasound methods. Visual condition score, however is a cheap and quick alternative.