[Introduction to Animal Science] ANSC 20
LABORATORY EXERCISE NO. 2
External Anatomy and Estimating the Body Weight of Farm Animals
I. Introduction
Anatomy is the science that deals with the form and structure of an organism. Its purpose
is to facilitate a universal understanding of the various life processes under physiology.
Physiology and anatomy are usually dealt with independently but both fields are necessary to
appreciate the different facets of animal development. Knowledge of the parts alone is not of
great practical value. This knowledge can be sustained by knowing the corresponding processes
involved in each structure. In the same manner, it is not possible to have a thorough
understanding of the functions without prior knowledge of the different parts.
Understanding the external anatomy of farm animals is crucial for effective management,
health monitoring, and productivity enhancement. Farm animals are different anatomically, and
each possesses external traits and characteristics that would readily distinguish the similarities
and differences between species, breeds, sexes, and ages. Knowledge of external anatomy aids
in selecting healthy and fit animals for production and breeding purposes, research work, buying
and selling animals, handling, and veterinary work. Likewise, this can also serve as a cue in
estimating their body weights which is essential during marketing, and in determining
appropriate feed rations, administering medication dosages, and making informed judgments.
II. Objectives
At the end of the exercise, the students must be able to:
1. Familiarize themselves with the different nomenclature that refers to the specific external
parts of the animal’s body;
2. Identify and locate the external parts of different farm animals; and
3. Apply the knowledge of external anatomy in estimating the liveweight of some farm
animals.
III. PROCEDURES AND MATERIALS
The instructor/professor will arrange a cross-farm visit to the MMSU Livestock and
Poultry Project. The students must strictly follow the biosecurity protocols of the farm.
Failure to comply will prohibit them from conducting this laboratory exercise on the farm.
A. External Anatomy
1. Draw and label the parts of the different farm animals.
2. Observe live specimens as the instructor/professor points out the various body parts
of farm animals (chicken, pig, goat, sheep, carabao, cattle).
3. The students should note the similarities and differences of the different parts
between species.
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B. Liveweight Estimation and Determination
1. The students will be grouped into 5 members/group. Each group is required to bring
a measuring tape.
2. Estimate the body weight of the animals using different methods and compare it with
the actual weight.
a) Eyeball Estimate. Through ocular evaluation, estimate the body weight (kg) of the
animal assigned to your group.
b) Body Measurement / Linear Regression Formula
b.1) Pig
1. Obtain a fabric measuring tape or a piece of string to measure. If using string,
mark the dimensions on the string and then measure the dimensions using a
steel tape measure.
2. Place the tape/string under the pig just behind the front legs and measure
the circumference of the pig’s girth in meters. This measurement is known
as the Heart Girth.
3. Then, measure the Length of the pig along its back from the base of its ears
to the base of its tail, again in meters.
4. To calculate:
Estimated weight (in kg) = Heart girth2 x Body Length x 69.3
b.2) Goat and Sheep
1. Let the animal stand upright on a flat ground area. Contraction of the
vertebra due to inconvenient handling or flexion of any body parts should
not be allowed to avoid inaccurate measurements. Wrong measurements will
result in wrong body estimates.
2. Using the measuring tape, measure the circumference of the animal (behind
the withers on top and just behind the elbows at the bottom), as shown in
the illustration (a). Make sure to measure girth in relation to the location of
the animal's heart. On a sheep, ensure an accurate measurement by
compressing the sheep's wool so that the circumference reflects that of the
body and does not include that of the body plus the wool.
3. Measure the length of the animal's body (from the point of the shoulder to
the pin bone), as shown in the illustration (b).
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4. Using the measurements from steps 1 and 2 , calculate body weight using the
formula: (Note: use body measurements in inches)
Estimated weight (lbs) = (Heart girth2 x Body Length) / 300
5. Convert the weight in pounds into kilograms (weight in lbs / 2.205).
a
b
b.3) Carabao / Cattle
1. Let the animal stand upright on a flat ground area.
2. Measure the circumference or hearth girth of the animal, as shown in "c" in
the illustration. Make sure to measure girth in relation to the location of the
animal's heart.
3. Measure the length of the animal's body, as shown in “b” in the illustration.
4. Using the measurements from steps 1 and 2, calculate body weight using the
given formulas:
a) Use body measurements in INCHES
Body Weight (lbs) = HG x HG x BL / 300 (Convert it to kg)
b) Use body measurements in CENTIMETERS
Body Weight (kg) = BL x HG2 / 10840
c) Use body measurement in METERS
Body Weight (kg) = BL x HG x 70
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c) Weighing scale. With the use of a weighing scale, determine the actual body
weights (kg) of the animals assigned to your group.
C. The materials to be used include live animals (pig, goat, sheep, cattle, carabao), tailor
measuring tape, bond paper, pencil or ball pen, calculator, and camera for
documentation.
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NAME:
COURSE & YEAR :
DATE CONDUCTED:
SCORE :
REMARKS:
STUDENT NO.:
SECTION :
DATE SUBMITTED:
Laboratory Exercise 2: External Anatomy and Estimating the Body Weight of Farm
Animals
WORKSHEET
1. Draw the following farm animals indicating their external parts:
a) Hen and Rooster
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b) Duck and Drake
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c) Gander and Goose
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d) Tom and Hen
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e) Boar and Sow
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f) Ram and Ewe
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g) Buck and Doe
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h) Cow and Bull
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i) Caracow and Carabull
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j) Mare and Stallion
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2. Distinguished external traits of the male and female of the different farm animal species.
SPECIES
EXTERNAL TRAITS
MALE
FEMALE
Chicken
Goat
Sheep
Pig
Cattle
Carabao
Use additional sheets if necessary
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3. Determine the body weight of the different farm animals using the three methods.
SPECIES
EYEBALL
ESTIMATE (kg)
BODY MEASUREMENTS
HEART
BODY
GIRTH
LENGTH
COMPUTED
WEIGHT (kg)
ACTUAL
WEIGHT (kg)
Pig
Boar
Sow/ Gilt
Grower
Grower
Goat
Buck
Doe
Grower
Sheep
Ram
Ewe
Grower
Cattle
Bull
Cow
Calf/Heifer
Carabao
Carabull
Caracow
Caracalf/
Heifer
Show your computations here (Use additional sheets if necessary):
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4. Discuss the importance of knowing the external morphology of farm animals
a. in relation to production
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b. in relation to animal environmental manipulation (e.g., housing)
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c. in relation to understanding animal behavior
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