Proper measurement of live body weight in animals, which is often hard in village settings due to a lack of weighing scales, is a prerequisite for achieving so many lofty goals that are always associated with either the medical or economic status of the animals.

Knowing the live body weight of small and large ruminants is important for a number of reasons, such as breeding, correct feeding, and health (Slippers et al., 2000).

Apart from taking the live weight of meat animals, researchers also use other parameters such as body length, width of pelvis, height at withers, and chest girths in order to adequately evaluate live animals (Atta et al., 2004).

Under standard conditions, properly calibrated livestock scales are the most accurate and consistent method for determining body weight. Under farm conditions, however, where scales and records may be absent, it may be difficult to know the weight of sheep and goats (Abegazand Awgichew, 2009).

Some of these standard weighing scales, coupled with their shortcomings, are too expensive for most small farmers (Mahieu, 2011). This has forced many farmers to rely on estimates of body weights using certain body characteristics that can be measured readily (Aladeet al., 2008).

Procedures for Estimating Weight of Small Ruminants

1. Weight band

Briefly, the weight band is wrapped directly behind the shoulder blade, down the fore-ribs, under the body behind the elbow and all the way around to the point behind the shoulder blade.

The ends of the weight band are overlapped on top, on the goat’s spine. Lastly, the resultant weight measurement is read off the weight band in kilograms.

2. Visual appraisal

Visual determination of the weight of animals is often fraught with errors, like using the same estimate for more than one breed of a particular species (Otoikhian, 2008). Body structure can be deceptive when estimating weight (Slippers et al., 2000).

For instance, Red Sokoto goats appear lighter than they actually are because of their light bones. Apart from bone and body structure problems in estimating weight, a white animal always looks bigger than it is (Otoikhian, 2008).

3. Body Linear Measurements

There are a number of linear dimensions that can be used to quantify the size of an animal and its weight. The most widely used body linear measurements include height at withers, heart girth, chest depth, body length, fore cannon bone, rump height, distance between eyes, ear length, ear width, paunch girth, and tail length.

Heart girth and cannon bone length are least affected by the posture of the animal. Abegaz and Awgichew (2009) described the linear measurement as follows:

i. Height at Withers (HAW)

This measures the distance from the surface of a platform on which the animal stands to the withers. The measurement is best made with a special measuring stick made with two arms, one of which is held vertical and the other at right angles to it, sliding firmly up and down to record height.

The sheep or goat should stand squarely on all four legs. The legs should be equally spaced and carry equal portions of their weight. The vertical arm of the measuring device is placed on the ground and ensures it is at a right angle to the platform. Then the other shorter arm is slid down until it just touches the shoulder at the desired point.

The vertical measuring device is withdrawn, and the distance is measured with a measuring tape. Alternatively, the vertical arm could have the measuring scale inscribed on it and the height read directly. This method can be used alone or in combination with the other linear measurements to get more accurate results.

ii. Heart Girth (HG) or Chest circumference

Heart girth is a circumferential measure taken around the chest just behind the front legs and withers. The measurement should be taken to the nearest 0.5 cm. HG is a highly repeatable measure, though it does vary somewhat with extremes of posture and perhaps as the animal breathes.

iii. Body Length (BDL)

Body length refers to the distance from the base of the ear to the base of the tail (where it joins the body). It can also be measured as the distance from the base of the tail to the base of the neck (first thoracic vertebrae), to the front of the chest, or to the tip of the nose. Extreme care is needed to ensure that the backbone is straight in both vertical and horizontal planes.

iv. Hip Width (Pin Bone Width) (HW)

Hip width is the distance between the outer edges of the major hip bones on the right and left sides. The hip bones are easily located and the distance between them is easily measured with a pair of large, half-round or oval-shaped callipers.

v. Rump Height (RH)

Rump height is the distance from the surface of a platform to the rump using a measuring stick as described for height at withers.

vi. Fore Cannon Bone Length (CB)

This is the length of the lower part of the leg, extending from the hock to the fetlock in hoofed mammals. It is a well-established fact that the linear development of different bones in the body is strongly related.

vii. Chest Depth (CD)

Chest depth measures the distance from the backbone at the shoulder (standardized on one of the vertical processes of the thoracic vertebrae) to the brisket between the front legs.

Precautions while taking body linear measurements

Since animal body movement and body posture can introduce errors into measurements and estimated weights, Abegaz and Awgichew (2009) suggested the following precautions be taken in order to counteract these effects.

When possible, choose measurements that are less affected by the animal’s posture. Standardize the position of all animals that are to be compared. Be patient and wait for an animal to stand correctly.

Read Also: Evolving Waste Management Industry Trends