Pre-slaughter preparation of broilers – Gaining every gramme of meat

29-06-2009 | | |
Pre-slaughter preparation of broilers – Gaining every gramme of meat

Margins on broilers are often very small, so it is not without reason that everything must be done to get the birds from the grower to the slaughtering line with minimal losses. After all, every gramme of meat counts. Proper management practices are essential, from the shed to the shackle.

By Ing. Fabio Nunes, Poultry Processing Consultant, Brazil

The poultry industry enjoys, among the animal protein production chains, an unquestionable worldwide
recognition for its outstanding efficiency. This is understandable, as the poultry business is responsible not only for the ever-growing production of huge amounts of meat annually, but mostly, for the crescent affordability of the nourishing, healthy and safe chicken meat and meat products that feed millions of people in every corner of the world every day.

As a contraposition, though, the poultry industry is also recognised as an economical activity of squeezed-margins, where profits depend, among other factors, strongly on scale of production – to dilute the operational costs – and highest operational efficiency. This is, firstly, to maximise the expression of the live raw material during the production cycle, and later to optimise the usability of every single gramme of carcass at the plants.

Wasted or saleable meat

Within the later context, a “gramme of meat” should be the measuring unit adopted by the poultry companies to gauge the degree of efficiency of each process and, consequently, the company’s competitiveness as well. The suggestion of this measuring parameter is not a matter of professional minimalism, but of professional realism, only.

Given the crescent capability of the processing plants, each “gramme of meat”, either wasted or harvested throughout the processing chain can easily account in a 1-year period for tonnes of either wasted or harvested saleable meat. Therefore, the watchfulness of each process should characterise the daily routine of those labouring in the poultry companies, from the top manager to the operator, aiming at optimising each single process and maximising the usability of every resource.

Once broilers have reached their slaughter weight it is time to take them to the processing plant. From this moment onwards and throughout the processing chain, none-physical characteristics of these birds, either good or bad, can be improved, but can be easily worsened in case a set of appropriate measures is not in place from the early stages of this process. These measures aim at shielding the carcasses from the insults they can suffer while on the move from the farm to the plant, which can easily waste part of the efforts and resources devoted to produce them. In this context, the intention of this article is to signalise, as a sort of an operational checking-list, the “hot-spots” scattered throughout the processing chain that need to be carefully managed to prevent or, at least, minimise physical losses.

Feed withdrawal

Broilers must be off-feed prior to slaughter to reduce the risk of faecal contamination during processing and evisceration. Different research results confirm that the best gastrointestinal clean-out is achieved when broilers are kept off-feed for 8-12 hours before hanging.

As the digestion cycle commonly lasts about 6 hours to conclude, broilers kept off-feed for less than 8 hours have an increased likelihood of being contaminated by either faeces or ingesta during the manual or, particularly, the automatic evisceration. Likewise, broilers off-feed for more than 12 hours are also subject to contamination, yet of different nature, during evisceration. In this case their intestines undergo a degradation of the epithelium, which results in the loosening of its mechanical strength. Weakened, the intestines can be easily torn during evisceration, allowing its content – not faeces, but the fluids resulting from the epithelial degradation – to spill onto the carcasses. Additionally, broilers deprived of feed and water for such periods of time experience significant and irreversible live weight shrinkage prior to slaughter.

As food safety regulations in many countries consider contaminated chicken carcasses inappropriate for human consumption, they ought to be salvaged by the online inspectors during processing. As salvaging often translates into significant weight loss to the company, contaminated carcasses are not just a public health issue, but also a noteworthy economical issue.

Broilers off-feed experience an inherent weight shrinkage prior to slaughter. The research works teach and the experience corroborates this weight shrinkage can range from 0.35-0.50% of the live weight per hour after 6 hours off-feed, and variation between the extremes is greatly influenced by the environmental temperature, i.e., the higher the temperature, the higher the weight loss will be. This live shrinkage is not further recovered in the processing plant any more. Commonly expressed in diminutive percentages and thought on a single-bird basis, the live shrinkage does not readily communicate to a careless observer, and at a first glance, the magnitude of its economical impact on a poultry operation. Nevertheless, when examined under the perspective of a longer period of time, a month for instance, or even a year, its economical damage potential can be comprehensively evidenced.

It is therefore of great importance that the processing companies carefully design, implement and manage its feed-withdrawal programme to balance these two important variables, cleanout of the gastrointestinal tract and live weight shrinkage and, thus, restraining the extension of its impact on the carcasses’ quality and yield. To attain these results, the responsible person for the programme must hold a significant knowledge of the process, its variables and the interactions among them.

Live catching

Live catching can inflict severe damage to the carcasses. These are mostly haemorrhages and fractures, which
are defects that are, according to their extension and intensity, likely to be salvaged when carcasses undergo sanitary inspection. The carefulness of the live catching operation and, for extension, of the broilers sent to the processing plant, depend on the harmony between the catching method used by the company – either by the legs, neck or individual – the efficacy of the catching crew super-vision, the flock withdrawal programme, and the motivation of the catching crew; surely the most critical component of this multi-factorial equation.

In Brazil, haemorrhages and fractures mostly associated with poor live catching damage can account for 2-3% of the processed carcasses. Altogether, they are the fourth most important cause of salvaging in Brazilian poultry plants. The removal of the bloody or fractured portion of the carcass by the sanitary inspectors subtracts, an average, of 15% of the carcass dry weight. By applying these considerations to an operation that slaughters 100,000 birds a day of 2.2 kg of live weight, one can easily envision the potential loss of these two lesions are significant: 100,000 bpd x 2.2 kg x 70% x 15% x 2.5% = 600 kg/day
600 kg/day x 26 days/month x 12 months/yr = 180,000 kg/year

Live hauling

The live transportation between farm and plant is very exhausting for the birds because of the heat stress associated with the operation. For compromising birds’ welfare, heat stress is a proven cause of transport mortality, and the mortality number can be worsened by the sanitary condition of the flock.

To attenuate heat stress, the trucks must protect the birds from direct sunlight and have means to remove, at least partially, the heat dissipated during the journey. The flock withdrawal programme must also harmonise the geographic distribution of the farms, the live weight of the birds and the number of either kilogrammes or birds per crate as to mitigate the impact of the “time of journey x heat stress level” binomial on the broilers.

The transport mortality is expressed, likewise, in diminutive percentages and usually seen under a single-truck perspective, what masks its real economical dimension and importance in the context of the processing chain. However, evaluated under a longer time-range perspective – for example, a month or year – the economical damage inflicted by transport mortality can produce some eye-popping figures. For example, for the period of a year, the impact of 0.05% transport mortality on an operation running 100,000 birds a day of 2.2 kg live weight (LW):100,000 bpd x 2.2 kg LW x 0.05% x 26 days/month x 12 months/year = 34,320 kg LW/year

As real mortality can easily average 0.30% in some Latin-American countries, due to the climate, the loss of live weight would then jump to 205,920 kg annually. Really meaningful, isn’t it?

Live hauling units

Companies should pay close attention to their plastic cages (still predominate in South America) and steel containers. These must be carefully looked after not just because they are a costly asset for companies, but, mostly, because they are the package that contains the broilers between the farm and the plant and, as such, they must be in good condition as to physically protect them till they are hung.

Poorly maintained or damaged cages and containers can easily injure the birds while they are on the move. Missing doors – often a problem when plastic cages are used – allow broilers to run away at any moment between the farm and the hanging area. Uncrated birds, which are off-feed for some time, waste energy while hanging around, increasing the carcass shrinkage; peck the soil for feed, thus ingesting contaminants; have the risk to be damaged or even killed by the live-haulers and, ultimately, need to be to rescued and placed back into crates, which means extra labour cost. In both cases the losses are inevitable and the damages inflicted to the broilers are irreversible. Therefore, processing companies should carry on in-plant routine assessment of the integrity of their plastic cages and containers to ensure all doors are on and are working properly, to move apart those units that may require maintenance and, finally, to dispose of those units that are no longer in working order.

Holding shed

The birds waiting to be slaughtered must be kept away from direct sunlight and the climate inclemency to reduce the live weight shrinkage and the heat stress – the main cause of death on arrival (DOA). Hence, processing companies must ensure that the live load is sheltered by a holding-shed that can be either an independent building contiguous to the plant or the live reception platform itself. The areas must be equipped with ventilation, fogger and thermometer equipment for proper control of the environmental conditions.

A mistake commonly seen in many plants is the misplacement of the fans in the holding areas. In nature, hot air, which is relatively light, naturally flows up and is replaced by cold air, which is heavier. This continuous and endless cycle is nominated natural convection. Therefore, to accomplish their task effectively the fans must be positioned respectively to the live load as to accelerate the flow of hot air that emanates from it instead of retarding it, as often seen.

Another common mistake is the use of the holding area as it was a parking lot instead a short-term transient area where the live loads remain under just while waiting to be slaughtered. Giving the waiting time (one of the components of the total time birds are off-feed) may increase the live shrinkage, dwelling time under the holding shed must be set to a minimum, unless in the event of an exception, and need to be routinely monitored. Likewise, the arriving live loads must be managed respecting the order established in the withdrawal
programme, unless otherwise oriented by the plant personnel. The inconsideration for the management of the trucks on a “first-in, first-out” basis may have implications on the size of the transport fleet, on number of DOA birds and on the live shrinkage percentage.

World Poultry Vol. 25 No. 2