Average Body Weight Calculation in Poultry Farming
Average Body Weight (ABW) is a crucial metric for poultry producers. To determine the average weight of your flock, you primarily need a suitable scale for weighing the birds. The process involves randomly selecting and weighing chickens. Typically, 1% to 1.5% of the chicks in the shed are weighed randomly every seven days. To minimize stress on the birds, the lights are usually turned off before selecting and weighing chicks from various points in the shed. When the chicks are smaller, they are placed in a box for weighing. Finally, all recorded weights are summed and divided by the total number of chicks weighed. The resulting figure represents the flock’s average body weight.
Formula for Average Body Weight (ABW):
Average Body Weight (ABW)= Total Weight of Weighed Birds /Number of Birds Weighed
Final Weight Measurement at Sale
At the end of the growth cycle, during the sales phase, weighing is conducted using truck weighbridges. First, the empty truck is weighed. Then, the truck is weighed again after being loaded with the chickens. The difference between these two measurements provides the total weight of all chickens in the truck. Finally, the sum of all total chicken weights is divided by the total number of chickens in the poultry house. This figure represents the average body weight at slaughter, which is vital for calculating the performance index of that specific rearing cycle.
Flock Weight Uniformity: A Key Metric in Poultry Farming Formulas
Flock weight uniformity is a vital, standardized metric and a potential indicator of animal welfare. It represents the percentage of birds in a flock whose body weight falls within a specific range: 10% above or 10% below the average flock weight. The higher the uniformity percentage, the more consistent the flock’s size. Uniformity serves as a measure of the variation in bird size within a group.
Poor flock uniformity (e.g., a high Coefficient of Variation or CV) can signal reduced animal welfare, general farm management issues, or underlying health problems. This can be caused by factors such as lameness, disease, or long-term issues with access to feed and water.
Flock uniformity is influenced by several factors, which are critical to consider when applying Poultry Farming Formulas:
- Brooding and the quality of the initial start
- Diseases
- Feeder space and access to feed
- Stocking density and competition for survival
- Feed distribution speed and feeding equipment
- Feeding schedule—the amount of feed distributed throughout the day
- Separation into weight groups
Calculating Flock Weight Uniformity
To calculate flock uniformity, use this essential poultry farming formula:
- Sample the Flock: Randomly weigh 10% of the birds in your flock, one by one.
- Calculate the Average Weight: Determine the average weight of the birds you sampled.
- Define the Target Range: Calculate the range that is 10% above and 10% below the average weight. Any bird whose weight falls within this range is considered to have uniform weight. Conversely, any bird outside this range is considered to be a deviation from the uniformity standard.
- Calculate the Percentage: To find the percentage of flock uniformity, divide the number of birds within the target range by the total number of birds you weighed and then multiply by 100.
The Flock Uniformity Formula:
Flock Uniformity Percentage = (Number of uniform-weight birds / Total number of birds weighed ) ×100
Understanding and consistently applying this poultry farming formula is key to optimizing flock health, growth, and overall farm profitability.
Article: How to Prepare Poultry Feed.
Calculating Live Chicken Weight and Meat Yield in Poultry Production
To accurately calculate live chicken weight and the average meat yield obtained from it, we need a few key data points:
- Live Body Weight (LBW): The weight of the chicken before slaughter (in kilograms).
- Carcass Weight (Meat Yield): The weight of the chicken after slaughter and evisceration (in kilograms). This includes meat, bone, and skin.
With these two figures, we can calculate several important metrics:
Meat Yield Percentage (Dressing Percentage)
The meat yield percentage, also known as dressing percentage, indicates what proportion of the live chicken’s weight has been converted into usable meat. This metric is crucial for evaluating different poultry breeds and the efficiency of the slaughtering process.
Formula:
Meat Yield Percentage=( WeightUsable Carcass Weight (without skin, viscera)/ Live Body)×100
Example:
If a live chicken weighs 2.5 kg and its carcass weighs 1.75 kg, the meat yield percentage is calculated as follows:
(1.75/2.5)×100=70%
This means that 70% of the live chicken’s weight has been converted into usable meat.
If you subtract the meat yield percentage from 100, the resulting number represents the carcass loss or dressing loss. Carcass loss is essentially the weight of the chicken’s skin and internal organs (viscera). The lower the carcass loss percentage, the better the poultry production efficiency and the higher the profitability for poultry farmers. It’s also worth noting that we generally expect higher carcass loss in lighter-weight birds and lower carcass loss in heavier-weight birds.
Average Meat Yield per Chicken
To calculate the average meat yield per chicken, you need data from multiple birds. You’ll sum the carcass weight of each chicken and then divide by the total number of chickens.
Formula:
Average Meat Yield= Total Carcass Weight of All Chickens/Total Number of Chickens
Feed Conversion Ratio (FCR): Essential Poultry Farming Formulas
The Feed Conversion Ratio (FCR) is a core metric and one of the most important poultry farming formulas. It measures the efficiency of feed intake to output. In simple terms, it’s the number of feed units a bird needs to produce one unit of product, whether that’s meat or eggs. A lower FCR is always better, as it indicates higher efficiency—the bird produces more output (meat or eggs) with less feed.
FCR for Broilers (Meat Chickens)
For broiler chickens, FCR is the amount of feed required to gain one kilogram of body weight. The formula is:
FCR= Feed Consumed (kg) / Live Weight Gain (kg)
For example, if 10 chickens weigh 31.48 kg in total and have consumed 36.807 kg of feed, their FCR is 1.169. This low number signifies excellent efficiency.
FCR for Laying Hens
For laying hens, the FCR is the amount of feed they need to produce one kilogram or one dozen eggs. The formula is:
FCR for Laying Hens= Feed Consumed (kg) / Total Eggs Produced (kg or dozen)
Advanced FCR Poultry Farming Formulas
At the end of a production cycle, it’s beneficial to perform a detailed technical and economic analysis. This includes several variations of the FCR formula, which provide a more nuanced view of farm performance.
- Technical FCR: This formula accounts for all animals, including those that died during the growth cycle. It’s a key indicator of a farm’s overall productivity. The formula is:
Technical FCR=Total Feed Consumed (kg)/ Total Live Weight of Birds Sent to Slaughter (kg)
- Economic FCR: This formula provides a more precise look at how much feed is converted into consumable meat. It subtracts the weight of non-edible parts (like bones) from the final weight. The formula is:
Economic FCR= Total Feed Consumed (kg) / Total Weight of Meat After Slaughter (kg)
- Corrected FCR at Fixed Weight: This is a comparative formula that standardizes the FCR across different flocks by calculating what their FCR would be if they all reached the same final weight.
- Corrected FCR at Fixed Age: This formula estimates the FCR by projecting the weight birds would have reached if they had all been slaughtered at the same age, based on their feed consumption.
Adjusted FCR: A Key Metric in Poultry Farming Formulas
Adjusted FCR, or Adjusted Feed Conversion Ratio, is a crucial metric for comparing a flock’s FCR against the target FCR provided by the breeder company (or feed company) for a specific weight .
This is a vital tool within the comprehensive set of poultry farming formulas.
A flock that reaches a higher weight will naturally have a higher FCR. To make an accurate comparison between flocks, you need to adjust the FCR to estimate what it would have been at a standard target weight. Adjusted FCR is a useful calculation for measuring a flock’s performance against a target weight and is especially valuable for breed comparisons, as it allows you to analyze different breeds at the same specific target weight.
This number is a significant indicator of a broiler’s health and productivity, showing whether feed and nutrient intake have been properly managed.
The formula for calculating Adjusted FCR is as follows:
Adjusted FCR=Actual FCR+( Target Body Weight -Actual Body Weight)/Factor
The Factor value depends on the unit of measurement used: use 10 lbs, 4.5 kg, or 4500 grams. According to the Ross catalog, the Actual FCR is the average FCR for the flock.
Article: Reasons for Broiler Weight Loss. In this article, we have explored the common causes of broilers failing to gain weight.
FCR vs. Adjusted FCR: A Look at Key Poultry Farming Formulas
A recent study published in the Italian Journal of Animal Science, a Taylor & Francis publication, highlights the difference between FCR and Adjusted FCR.
“FCR represents the amount of feed consumed to produce one kilogram of live broiler weight, which is the main factor in reducing production costs (Marco et al. 2013).” This is a fundamental concept among poultry farming formulas.
The article continues, “The calculation of Adjusted FCR at a specific weight (e.g., 2.6 kg) is necessary to make comparisons among broilers with different weights, as well as between broiler farms (Liang et al. 2013; Aviagen 2014).”
For example, imagine a broiler catalog states that at 21 days, a chick should weigh 925 grams with an FCR of 1.24. However, your chickens weigh 900 grams with an FCR of 1.27. By using the Adjusted FCR formula, you can determine that if your chicks had reached the target weight of 925 grams, their FCR would have been 1.38. This shows the importance of using adjusted figures to get a true picture of performance.
This distinction is crucial for accurate performance evaluation and is a key part of the essential poultry farming formulas used for optimal flock management.
Calculating Coefficient of Variation (CV) in Poultry Farming
The Coefficient of Variation (CV) is a vital tool among poultry farming formulas. CV measures the flock’s weight dispersion around the average weight. It’s essentially the ratio of the Standard Deviation to the Average Body Weight (BW). A lower CV indicates a more uniform flock, which is a sign of good management and health.
The formula for CV is:
CV= (Weight Standard Deviation/ Average Body) ×100
While calculating the standard deviation manually can be complex, it’s very easy to do using software like Microsoft Excel. You can simply use the STDEV function on your weight data to find the standard deviation, and then apply the poultry farming formula to get the CV for your flock.
To grasp the concept of Coefficient of Variation (CV), let’s look at a practical example using common poultry farming formulas. For a broiler flock with an average body weight of 2550 grams, a standard deviation of around 250 grams is typical.
Using this data, the CV is calculated as 9.80%. The lower this number, the more uniform the flock’s growth. A higher CV indicates greater weight variation within the flock, which can signal issues with management, health, or nutrition.
The formula for calculating CV is:
(Standard Deviation/ Average Flock Weight) * 100 = CV%
To find the average flock weight for this calculation, you can randomly weigh 10% of the birds in your flock and then compute their average weight.
Article: Broiler Feed Consumption Guide Per Cycle, with Catalog of Daily Feed Intake, CV, and Chick Weight
Poultry Farming Formulas: Calculating Flock Livability and Mortality
Livability and Mortality are two sides of the same coin and essential metrics in poultry farming formulas. Livability refers to the percentage of birds that survive in a flock, while mortality is the percentage of birds that die. These figures are calculated at the flock level and are expressed as percentages.
For laying hens, mortality is typically highest at the beginning and end of the laying period. An average mortality rate of around 1% per month is normal, but a consistent increase of 0.5% over several consecutive weeks can indicate a potential problem. Laying hens generally have a mortality rate between 0.7% and 0.8% over a four-week period.
For broilers, a livability rate of 97% to 98% is considered normal, which means a mortality rate of 2% to 3% is generally acceptable.
Livability Formula
To calculate the livability percentage for a flock, use this straightforward poultry farming formula:
Flock Livability Percentage=Number of Healthy Birds at the End of the Period (Sold) ×100 / Number of Birds at the Start of the Period
Calculating the Production Efficiency Factor (PEF)
The Production Efficiency Factor (PEF) is a global standard used to compare the performance of poultry flocks. This value depends on key factors like final body weight, age, livability, and feed efficiency. As a result, any negative impact from health issues, environmental stress, or feed quality will affect the PEF. A higher PEF indicates better flock management and higher profitability. A score above 100 is generally considered a sign of favorable conditions.
To evaluate a broiler house’s performance, the Production Index, along with the Feed Conversion Ratio (FCR), is crucial. The Production Index includes factors like flock mortality, livability, age, feed conversion, and final weight. The higher this index, the better the overall management of the flock at the end of the cycle. However, if the PEF is low, all records, management practices, and health factors must be reviewed to determine the potential causes of poor production.
Acceptable livability PEF scores are as follows:
- PEF above 300: This typically indicates very good performance and strong farm management.
- PEF above 350: This is considered outstanding, world-class performance, and reflects very high efficiency in all aspects of production.
Understanding the European Performance Efficiency Factor (EPEF)
The European equivalent of PEF is known as the European Performance Efficiency Factor (EPEF). In Europe, due to strict animal welfare standards and advanced management, target EPEF numbers are typically very high. A good EPEF in Europe is recognized as a sign of excellent and sustainable performance, often achieved by flocks with superior genetics and precise management.
- EPEF above 350: This is considered very good performance, reflecting an efficient and profitable production system.
- EPEF above 400: This figure indicates outstanding, world-class performance. Achieving this number means the farm is operating at the highest level in terms of management, nutrition, flock health, and environmental conditions.
In short, a higher EPEF means the farm is producing the highest weight and health in its flock with the least amount of feed and in the shortest time. Achieving a high EPEF directly leads to reduced costs and increased farm profitability.
Poultry Farming Formulas: Downloadable Excel File for Broiler Performance Metrics
To help you with your flock management, you can download an Excel file containing essential poultry farming formulas. This tool is designed to calculate key metrics for your broiler flock’s performance throughout a growth cycle, including:
- Feed Conversion Ratio (FCR)
- Average Weight
- Production Performance
Refrences:
Marcu A, Vacaru-Opriş I, Dumitrescu G, Ciochină LP, Marcu A, Nicula M, Peţ I, Dronca D, Kelciov B, Mariş C. 2013. The influence of genetics on economic efficiency of broiler chickens growth. Lucr Stiint Zooteh Bioteh. 46(2):339–346. [Google Scholar]
Liang Y, Kidd MT, Watkins SE, Tabler GT. 2013. Effect of commercial broiler house retrofit: a 4-year study of live performance. J Appl Poult Res. 22(2):211–216. [Web of Science ®], [Google Scholar]
