Lamb killing-out percentage and yield

Killing-out percentage (KO%) is important as it determines how much saleable carcase weight is obtained from your lambs. Find out what affects the percentage and yield.

The KO% is carcase weight as a percentage of liveweight. For example, a 22 kg carcase from a 49 kg lamb would have a KO% of 44.9%.

Factors affecting KO% include:

• Breed and genetic performance of the sire and dam
• Stomach content at live weighing – an empty stomach gives a higher KO%
• Seasonal variation – spring lambs (NSL) tend to have a higher KO% than hoggets (OSL)
• Milk-fed lambs have a higher KO% than weaned lambs
• Fatter lambs have a higher KO% than lean lambs
• Sex – females generally have a higher KO% than entire males
• Fleece length and type – heavier fleeces result in lower KO%
• Weather – dry lambs have higher KO%
• Lambs with long tails, testicles or horns have lower KO%

Meat yield is the total percentage of saleable meat from a carcase.

Carcases with better conformation yield a greater amount of saleable meat.

Fat level has the greatest influence – the fatter the carcase, the less meat is available for the processor to sell.

Table 1. The percentage of saleable meat from carcases of different fat classes

In meat processing, carcase balance refers to the practice of efficiently utilising all parts of a carcase, ensuring that the demand for different cuts and by-products is met and that no part of the animal goes to waste.

The aim is to maximise the value derived from each carcase and enhance the sustainability of meat production.

Carcase balance involves finding markets for less desirable cuts, by-products (such as bone, fat and organs) and even inedible parts of the animal.

It also requires adjusting to changes in consumer demand, seasonal variations and unexpected events, like a pandemic, that can shift demand towards specific cuts.

The fifth quarter is comprised of animal material that has a value in addition to the carcase meat.

• Red offal: heart, liver, kidneys
• Head meats: brain, head meat
• Carcase meats: thick and thin skirts, tail

• Stomach, intestines, fat, bone – tripes, sausage casings, lard and cooking fat, gelatine
• Skin/pelt – leather
• Fats – cooking oils, lard or biodiesel

Other viscera, e.g. lungs, pancreas blood, bones – meat and bone meal (MBM), processed animal protein (PAP) or pet food

The animal by-product (ABP) regulations and improved export opportunities have resulted in an increase in consumption of fifth-quarter products as well as opportunities to use the ABP for pet-food, fertiliser and energy generation. This is benefiting the meat industry both financially and environmentally.

The larger abattoirs sell the majority of their fifth-quarter products directly to the home market or vacuum packed and/or frozen to the export market, rather than disposing of them for rendering or pet food. 

The price of skin can have a large effect on lamb value.

This is largely dependent on export markets, particularly Russia, Turkey and China, but is also affected by quality.

Take care when handling and dagging sheep to avoid damaging skins.