What are the advantages and disadvantages of water chill compared to air chill?
As far as the advantages and disadvantages of water chill compared to air chill, it depends on factors specific to different regions around the world. This includes the type of market and product mix. For example, in EU and countries that export to the EU, water chill systems are not allowed because of regulations on moisture pick-up. Product mix in EU countries are also different and any excess water is seen by consumers as extremely negative. There is an increase movement to air chill in traditional water chill markets and this is being marketed as an upgrade.
Water chill is still mostly used in United States and most parts of the world outside EU. In majority of United States, the products are value added and majority of consumers seem to prefer the water chill appearance. As far as economics is concerned, water chill systems are less expensive as they require less utilities and refrigeration cost. It also covers much less floor space. There is also a significant yield difference between the two methods. In full cut-up debone plants, there is at least a 4% advantage in water chill and the advantage is much higher in a whole bird and bone in product mix.
How do defects cause economic impacts on processing plants?
Losses due to increased cost is proportional to defect level. In general when flocks have high levels of defects, the plant will have to reduce slaughter speed or add additional personnel to do trimming and sorting of the birds.
When slaughter speed is decreased, efficiency is reduced as this will lead to an increase of all fixed costs such as indirect labor cost, utilities, rent, taxes and other support costs. The loss of parts or sometimes condemned whole birds will be a total loss of live production cost and potential sales revenue. These losses will also reduce yielded weightage, and this will increase direct labor and total plant cost.
As far as economic impact and profitability to processors, the key will be the product mix of the plant. In plants with extensive cut-up and debone operations, the losses can be minimized by only losing the classification grade and yield value on areas where, for example, a scratch was located along with the yield loss of any trim of the affected area. In plants with mostly whole bird product mix, the losses can include the entire bird, which in some plants can be as much as 50% of the value of the bird going to undergrade or a local market instead of premium grade products.
What are the factors that cause variation in liver color?
Liver color can be affected by a lot of different things.
Color of the liver varies depending upon the condition of the liver. The color of liver varies within a poultry population of healthy flocks too. Some of the reasons for variations in color of livers are caused by challenges during grow out period and nutrition that will make the liver color change in a small or high scale, depending upon that amount of challenge that the liver is exposed to. Some of these challenges include aflatoxins, ochratoxins, fumonisins as well as high energy levels in the diet.
Processing errors at the plant such as incomplete bleed out in some birds can cause livers to be more engorged with blood and appear darker. However, the key factor observed is natural color variation due to feed withdrawal and the feeding patterns of birds. Liver color and paleness is highly correlated with periods of time where birds are fasting due to feed withdrawal. Livers become less pale as liver glycogen content is reduced when birds are off feed for longer period of time (Trampel et al 2005, Vieira et al 2012). Birds in broiler house do not eat at same time and even if the feed withdrawal program is followed correctly, there will still be some variation from bird to bird during feed withdrawal period.
What are the causes of feed residue in the proventriculus?
Feed residue in proventriculus is due to two main causes. Non-infectious causes include oral exposure to biogenic amines, mycotoxins, lack of dietary fiber and excessive copper sulfate. Infectious causes and agents that have been implicated include adenovirus, reovirus, infectious bronchitis virus (IBV), infectious bursal disease virus, Clostridium bacteria, fungal infections by Aspergillus and Fusarium, Candida albicans infection and megabacterium. It is estimated that between 15 to 25 percent of birds routinely necropsied in broiler, breeder or layer farms suffer from proventriculus or gizzard erosions. The consequences of such erosions should not be underestimated as proventriculus and gizzard are very important digestive organs. Lesions make digestion painful and affected birds consume less feed and show depressed growth.
What to expect and how to minimize wings bruises and broken wings in unstunned slaughter process such as halal slaughter?
The halal slaughter when done correctly with no pre stun process will always have more wing and joint damage, especially shoulder and inner thigh, compared to other slaughter methods using stunners. There will be death struggle without the pre stun process. Grade checks, depending on criteria used, can show major shoulder and wing damage of about 30% and more than 10% wing breakage. The key to reducing damage in unstunned slaughter starts with proper cut. It must be precise and not go too deep to prevent immediate death struggle. This will reduce the overall damage by minimizing the time birds are in death struggle. If pre stun is not allowed, the next best thing is to stun after cut. An electrical plate system can be set up and this will reduce the damage. Other steps that can be taken is the use of restraint cones and belts. Another very effective method is the bucket system.
What is the recommended scalding tank and screw chiller temperature?
The temperature of scald tank will depend on line speed, number of scald stages, total dwell time in scalder, agitation level as well as number and type of pickers. It is recommended to scald as low as possible to achieve the desired product goals with the available system. With a properly balanced system and cuticle off product mix in a minimum of 90 seconds dwell, the temperatures should be below 57C.
Can bruises caused by stunning process be confused with lesion from Reovirus infection?
It is highly unlikely that stun damage can be confused with Reovirus lesions or vice versa. Novel Reovirus causes viral arthritis and the lesions are primarily localized in the hock joints. Stun damage will primarily affect wings, shoulder, internal muscles and organs. Stunning can also affect inner thigh but not hock joint.
How does stunning cause wing damages?
Stunning causes wing damage in three ways. Firstly, excess wing flapping in the stunner cabinet from pre-shock, poor connections, poor water management and conductivity and poor height adjustment. This usually causes red wing bruises, red wing tips and broken wings from drag back. Secondly, excess voltage causing over stunning which results in shoulder damage and wing bruises. Lastly, under stun or birds not stunned resulting in death struggle during bleed out leading to blown shoulders, red wing tips, major wing bruises and broken wings. Excess flapping will also cause blood to engorge in the wing veins and this will cause poor bleed out of those areas.
What is the ideal frequency and voltage for stunning a line of 6000 birds per hour?
Stunning voltage and frequency depend on the consistency of the system along with religious or regulatory requirements. It will also depend on the type of stunner and control package. Assuming a standard stunner with good set-up, start by setting voltage at 60V with a frequency of 250hz. The settings will need fine tuning to maximize results and the key is to stun with best practice outcome-based approach.
Best practice means to have a consistent as possible operation and reduce as much as possible the variation in the process. In order to do this, start with the basic principles and make sure they are being followed. Length of stunner should be matched to line speed along with adequate dwell time in the stunner. Example stunner dwell time of 10 seconds in high speed lines and 15 seconds in very slow lines is necessary to buffer variation of misfeeds, process errors and to minimize unstunned birds.
The breast rub must transition all the way into the stunner and the ground bars should be located and offset on either side of the shackles. The ground bars must capture and immediately contact the shackle prior to the birds entering the bath and complete the circuit and maintain shackle contact with the ground bar throughout the complete length of the cabinet. Water overflow must be at the exit end of stunner instead of entrance to prevent pre stun. Volume of water for makeup of the stunner flow should be controlled to prevent a constant or unbroken stream of water to the floor which will disrupt settings and wastewater. Temperature of water in the bath should be above 25°C to maximize conductivity. The shackle on line should be in good repair and line should always be full without empty shackles with all birds properly hung. This maintains a constant number or resistors in the system which is critical.
The foot spray must be located just inside the entrance end of the stunner to increase conductivity without causing pre shock. Spray must be positioned spraying in the direction of the birds travel and hit the feet /shackle contact area with very fine mist but not stream of water just as the birds' head contact the bath. Always add 1% salt solution to condition the water and help conductivity. At each flock change, adjust the stunner height to water level just below wings of biggest birds. This ensures the smallest birds will still be stunned.
Set lowest possible voltage that meets regulation and gives an adequate stun. Do not under stun with voltage that is too low to minimize product damage from death struggle. When adjusting the frequency of stunner, consider regulations and minimize damage of stun amperage and effect the frequency has on the birds. Frequency at lower ranges will increase the stun effect. Higher frequency will decrease the stun effect. The critical aspect is do not run a combination of low milliamp and high frequency that will show a lot of heavy wing flapping with movement out of the stunner. Best practice to prevent damage is to always stun at lowest possible milliamp per bird and highest frequency that will meet governing regulation and properly stun the bird.
Adjustment can then be made using outcome-based method. Take all steps to make the system consistent and then adjust the stun equipment on an outcome base using best practices of the total system instead of only voltage and frequency settings.
Outcome based has two parts to evaluate results:
Part 1, at the stunner exit and bleed tunnel, visible appearance of best results here will be over 99% of the birds exiting the stunner will have wings tucked and rigid bodies, eyes fixed with no reaction when the eye is touched, necks down or arched, no heavy wing flapping with very little vocalization in the stunner. Mild flapping and body tremors in some birds is normal. There should not be any death struggle in the bleed out process.
Part 2, inside the plant, visible appearance of best results here is proper bleed out with minimal engorged veins in shoulder, minimal wing and shoulder damage, minimal breast and tender damage and minimal inner thigh damage.
Once the process is consistent, we may consider the following.
1. Reduce the frequency to 250KHz. Start at 60 volts. If birds do not meet properly stunned criteria, then increase voltage by 5 volts at a time until they are properly stunned. Observe the birds coming out of the stunner and reduce the voltage slowly, example 2 volts at a time until birds are no longer properly stunned, then increase back up 2 volts.
2. Once the voltage that properly stuns birds is achieve, start working the frequency back up. When you reach the maximum level that the birds are still properly stunned that is you setting for that flock.
3. It is still possible to have good results at end of stunner and be over stunning. In this case, use part 2 evaluation to access bird damage. If damage is too much, then a compromise must be made for current or voltage for frequency.
4. We need to reassess stunner and start again with a reduced frequency of 200KHz and follow through with steps 1 ,2 and 3 again.
5. The goal is to find best combinations of settings that gives properly stunned birds with minimum damage.
What are the drawbacks of using cage coops for the harvest process and would there be any significant effect on meat quality due to incorrect transportation and handling?
Generally, most of the auto and modular systems provide good results if correctly maintained while being suitable for high speed lines. They may not work in all broiler houses and will require forklifts in loading, unloading as well as very specific unloading systems. The most used system in the United states is a dump system which is very efficient and economical in loading, transporting and unloading. However, the narrow openings create a lot of bruising during loading and unloading. The dump step in the process can also cause major wing defects. If plastic type coops are used, there must be a good training program on how to correctly load in the broiler house, unload at the plant and the correct method to remove birds from the coop to hang on the line. The plastic coop also makes it difficult to supply and run high speed lines.
Improving Yield by Reducing Defects in Processing Plant
David Beavers- WTS
July 29, 2020