Consequences of poor pelleting and feed processing - poor immunity and health
The poultry industries have undergone remarkable change and growth over the last 30-year, such that today we see 2.5-kg male broilers at 35 d of age, and white-egg layers are capable of producing in excess of 330 eggs in 52 week of lay. There is often debate about there being an end point to this increased genetic potential, yet the geneticists tell us that selection pressure will be little reduced in the foreseeable future. Feed will always be the major input cost for poultry meat and egg production. Hence undoubtedly, the feed quality in general is going to be the single largest factor influencing the success of future production systems.
The progress in the technology of feed manufacture during the past 50 years represents a major and necessary development in improving bird performance. The technology has progressed from simple mixing of mash feed to pelleting, which involves various physical, chemical and thermal processing operations. Currently, majority of the feed used in the production of broilers is fed either in pelleted or crumbled form. Offering feed to poultry in pellet or crumbled form has improved the economics of production by improving feed efficiency and growth performance. These improvements are attributed to decreased feed wastage, higher nutrient density and reduced selective feeding.
Though there are many studies available now that confirms higher broiler growth and feed intake when they are offered quality pellet diets compared to mash but very few studies are available which talks about the deleterious side effects of feeding poorly processed pellets along with the high fines except on the broiler growth rate and efficiency of gain. This write up highlights the limited amount of our work conducted and reported regarding negative effects of poorly processed feed in tropical feed industry on bird's immunity and hence increased disease challenges. The current tropical feed industry is struggling to produce high quality pellets because of inefficient starch cooking or conditioning in the conditioner due to hot climate, high mash meal temperature and dried up ingredients, which is not only masking the benefits of feed processing but also offering different immunity and health challenges apart from performance losses.
What is Poor Pelleting?
Pelleting is system of a modification of the mash system by mechanically pressing the mash into hard dry pellets or "artificial grains". It is generally accepted that, compared to mash, the feeding of pellets improves feed conversion, broiler performance with an increased feed intake. Reasons for the enhanced performance may be due to increased digestibility, decreased ingredient segregation, Decreased feed wastage, reduction of energy during prehension and improved palatability and so the modern broiler industry has traditionally fed a pelleted diet to birds. The quality of pellets must be taken into account also because feeding pelleted rations is not enough to ensure enhanced performance of poultry but also the proper growth, immunity and health status of the bird. There are a number of excellent methods to objectively measure and record the quality of pellets during the manufacturing process.
Other disadvantages of poorly formed pellet includes:
1. Dusting potential
2. Flow properties and proportioning gets impaired by fines
3. Remainders in silos, bins and pans will be increased by fines
4. Fines and dust are preferred nutrients and habitats for germs and micro organisms of any kind
High fines in the pellet can be a menace and mainly attributed to the issues of "soft pellets" at the press. Improving pellet hardness or durability is an effective means of reducing fines. Pellet durability may be improved by manipulation of diet formulation and improving feed manufacturing practices. Feed manufacturing practices adjusted to suitable to ambient climatic conditions and native ingredients will have a profound effect on pellet durability and potentially involve less expense than changing raw materials or using pellet binders.
Poor steam conditioning, poor mash hydrolyzation and poor starch cooking is an established fact in tropics because of hot environment and dried up feed ingredients. Our internal survey of almost 1500 feed mills from Asia has taught us that poor starch cooking is the main culprit of poor pelleting and poor pellet quality in the region.
Forcefully pushing the badly conditioned and poorly hydrolyzed mash through the die, results in huge loss of micronutrients due to additional heat generated inside the die as well as accelerated Maillard reaction (amino acid reacting with reducing sugar from the friction heat) and dextrinization (basically burnt to a certain extent through a thick die passage).
These problems are more noticeable with the use of thicker die (for a high die compression rate) to achieve the obsession for a good PDI as reduction in "micronutrients" content of the feedstuffs as a result of a thermal process directly depends on the severity process.
This has a detrimental impact on all the micronutrients and macronutrients, which in turn affects livestock immunity, health, and productivity all.
Further the economic aspect of moisture retention in feed processing is strongly recognized but there are several other interesting aspects attached with this moisture content of the feed as well. One of them is its consequence on keeping quality and duration for how long it stays fresh. Nothing beats a freshly cooked meal, and this holds true not only for humans, but for animals, too. Feed components start deteriorating as soon as they undergo the feed mixing process. Feed exposed to high temperature (and) or high humidity, or feeds containing increased levels of sensitive ingredients, will have a reduced shelf life. Cooked starch starts looking "stale" as soon as it cools down, Vitamins starts loosing potency almost instantly when intermixed with certain trace minerals, fats and lipids start oxidizing as soon as they come into contact with air and this is why it is important to control water activity (aw) of feed to keep these vital nutrients intact and keep the feed remain fresh till it is consumed. It is not that feed becomes unsuitable to consume so fast but it is the significant losses of micronutrients from mixing of feed to actually consume by the hyper producing birds.
"Non-durable" or Poor Crumble Quality and Its Effect on Chick Growth
Profitable broiler operation requires optimal feed intake throughout the growing period. Optimal feed intake is dependent on a number of factors such as environmental conditions, diet nutrient density and physical feed quality, which is considered to have a very significant impact on broiler growth. To ensure maximum utilization of energy, protein, and every nutrient of the diet, a right proportion of these nutrients are necessary for optimum growth of the birds and for minimization of the surplus use of vital dietary component, and because the first few days after hatch now represent a greater percentage of a broiler's lifespan than any time in history, it is critical that the bird be given every opportunity to get off to a good start.
If You Do Not Build It, They Will Not Grow. Early feeding have a major impact on the early development of poultry. It is clear that feed intake is a determining factor in immune development, intestinal development, and muscle development. If any of these areas are not developed properly early in life it is likely that the bird will not grow to its full potential.
Crumble is a type of feed prepared at the mill by pelleting of the mixed ingredients and then crushing the pellet to a consistency coarser than mash. Recently this form of feed has become popular in broiler production during the early chick phase due to its convenience of feeding and better body weight gain during first few days of life cycle. Several reports have supported that chicks fed the crumbled starter diet consumed more feed, shown highest weight gain and offered best FCR.
While the idea and performance of feeding crumbles to chicks appears highly promising, there is very less research work and field communication reported which talks about the quality of crumbles at feeding pans. Crumble feed is certainly the best for the chicks, but empahsize on the quality of crumbles is equally important and that quality can be measured in the terms of durability of crumbles. Soft crumbles coming out of soft pellets tend to create too much dust that poses multiple disease and developmental challenges apart from performance issues in young ones.
While few researchers confirm issue of fine ground particles or coarse particles, but there is preferential selection by chicks for crumbles than the fines into it. The fines present in the crumble feed can make the digesta very viscous and can severley impact the intestine and increase gut disease apart from lower feed intake and weight gain. Too much fines in the crumbles during early days of chicks organ development may also tend to poor development of gizzard and digestive functions.
The gizzard is a muscular organ that reduces the particle size of ingested foods and mixes them with digestive enzymes. The mechanical pressure applied in grinding by the gizzard may exceed 585 kg/cm2 . The development of digestive tract of poultry, especially the gizzard, is known to be influenced by crumbles quality, particle size and fines which is evident in chickens at 7 days of age. Greater gizzard development and lower gizzard pH in 7-day old chicks fed with high quality crumbles compared with those poor quality crumble diets have been observed and reported. Chicks fed crumbles with high fines may have relatively underdeveloped gizzard, which may functions as a transit rather than a grinding organ.
Several research which compared the feeding efficiency of mash, pellets, and reground pellets, have confirmed that broilers growth response was lost when pellets were reground to mash. Though Metabolisable energy (ME) was not affected by pelleting, but the diet fed as intact pellets had approximately 30% more calories of productive energy. It has been speculated that this was the effect of less energy needed to eat pellets compared to mash. In a time trial, chicks fed mash spent about 103 minutes of a 12-hour day eating versus only 34 minutes with pellet-fed chicks. Also feed conversion (gain/feed) benefits from good pellet quality. Research and practical findings on commercial farms often indicated that on farms with good quality pellets, feed conversions were always better than when the feed was fed as mash or had a high percentage of fines.
Poor Pelleting and Flock Uniformity
The chicks are not all equal when they arrive at the farm, as they have different maternal origins and embryonic conditions, then they hatch at different times, transported in different positions in the delivery vehicle and finally, because the living conditions are never perfectly equal throughout the whole house. Poor uniformity is one of the first indications of abnormal performance or health problems. The level of uniformity basically dictates the final result as poor flock uniformity goes hand in hand with delayed growth, rejects, and poor FCR. Poor flock uniformity in broilers can have a huge effect on profitability and hence Improving feed homogeneity and increasing nutrient levels ( a major benefit of pelleting) in the feed as well as using easily mixable nutrient sources can improve broiler uniformity.
THough, not many studies have explored the effect of feed homogeneity on broiler performance and flock homogeneity, but the few studies conducted have clearly showed an effect. One study conducted on feed form to study the uniformity of broliers when assessed by the percent-age of birds within the 15% range of the average weight of broilers in each pen, clearly confirms a greater flock uniformity when broilers were provided with quality pellet ration than broilers fed mash rations. This also confirms the fact that tere is a great degree of variation in nutrient distribution between pellets and its fines apart from creating a difference in productive enrgy. Analysis of pellet fines obtained from same pellet bag shows surprising low levels of protein in the fines but higher level of fat, higher level of calcium and phosphorous and almost all of the Zn was present in the fines.
Poor Pelleting and Mold
Processing feed conditions make feed more readily digestible by animals and also more easily digested by molds. After pelleting, it is utmost important to control mold contamination and mycotoxins development as mold development in pelleted feeds is faster than in non- pelleted ones. A suitable storage condition is also important to restrict recontamination of feed after thermal processing.
More than 2 lakh mold species are harmful to man and animals. The harmful mold causes diseases and poisoning in animals with the help of mycotoxins. The fungus and molds count of feeds and feed ingredients totally depends on, how feed is stored as per environment condition. The higher the moisture content of feed and feed ingredients greater is the development of fungus in this process, the amount quantity of feed stored, length of feed stored, temperature and humidity plays a vital role.
It is important to remember that it is the microenvironment that provides the proper environmental condition for growth of fungus and mold. The fungus invasion can reduce the protein content of feed, and feed ingredients. Once mold growth is sufficiently advanced for measurable proteolysis, all the amino acids are affected with lysine and arginine levels are most severely affected. Feed vitamins levels including both fat and water-soluble are also destroyed by fungus and molds.
Poor Pelleting and Respiratory Challenges/Ascites:
Because of poor pellet quality and reduced hardness, fines up to 50% have been reported from the field conditions. These incidences of high levels of fines in the field are not only associated with poor live weight and FCR but also has huge dusting potential posing respiratory challenges. The fines in the feed are inhaled by the birds and while exhaling they settle in various part of air sacs, specially thoracic air sac where air stays for longer period which leads difficulty for birds to breath hence deficiency of oxygen in the blood.
Also mold spores appear almost immediately within 12-24 hours after the bagging of the feed in field conditions. The moisture content of the feed usually ranges from 10 - 13%, which when exposed to environment and retained in the pans as uneaten leftover for a week or more before it is consumed in automated feed system gets heavily contaminated with mold spores. Birds fed with lots of fines in feed with increasing mold spores infestation and placed in environments contaminated with aerosolized conidia (mold spores) may show significant pathology after only a short duration of exposure.
Anatomy and physiology of the avian lung-air sac system are strikingly different from that of the broncho-alveolar lung of mammals. Avian air sacs are particularly prone to contamination because they are submitted to an airflow that favors dust/particles/fines deposition. Mold spores are small enough, 2-3 μm in diameter, to bypass initial physical barriers and disseminate deeply in the respiratory system.
It has been suggested that the dust created by the fines of the feed and mold appeared in the stale feed get inhaled by the birds during increased number of pecking, leading to irritation and reduced efficiency of the airways. Poor air quality, environment dust and respiratory diseases also imapires the perfusion capacity of chicken lungs, creating an imbalance between oxygen supply and the oxygen required to sustain rapid growth thus predispose birds to ascites by causing respiratory damage.
Ascites is a disease, which causes death in poultry apparently because of fluid retention. Ascites is commonly known as "water belly". There is no known cause and no apparent cure. There are theories that the amount of heat in the early days of the chicken or turkey's life, or stress, may be the cause of ascites but there is no significant data to support these theories. However, invention with antifungal agents to reduce the symptoms associated with ascites and preventing mortality from the disease confirms the role of mold and its spores as a major causative factor for the ascites.
The commercial broiler of today represents the culmination of dramatic changes over the past 60 years. Genetic selection processes that focused mainly on production traits putting heavy pressure on the bird's cardio respiratory system and immunity.
Increase in metabolic rate, coupled with exposure to environmental conditions such as temperature, lighting and ventilation, and nutritional factors such as feed form or fines into it, all seem to promote the development of ascites. The primary cause of the ascites syndrome, however, is believed to be hypoxia/hypoxemia when the bird's demand for O2 exceeds its cardiopulmonary capacity and causes pulmonary hypertension, which results in development of the ascites syndrome. Inadequate ventilation and dusty feed increase the risk of bird exposure to aerosolized spores. Acute cases are seen in young animals following inhalation of spores, causing high morbidity and mortality. The chronic form affects older birds and looks more sporadic.
Poor Pelleting and Crop Mycosis or Mycotic Diarrhea
Crop mycosis or Mycotic Diarrhea is a reference to a condition called Sour Crop that is caused by a type of yeast called Candida albicans. This causes thickening of the crop surface characerized by whitish thickened areas of the crop and proventriculus and may keep nutrients from being properly absorbed from the intestinal tract. It may lead to destroy the tissues of the upper digestive tract particularly the crop and gizzard. It is believed that in severe cases the disease may also infect the intestinal tract. Feeds and fluids may retained in the crop, causing it to enlarge. The orientation of the crop of a chicken is such that any feed or water consumed tends to flow past and contact the crop. Particularly, an environment which is warm, moist, possesses a neutral pH, contains oxygen, includes a substrate which enhances yeast growth.
Poultry of all ages are susceptible to the effects of this organism. The disease affects primarily broilers, laying hens and turkeys. Mycosis is transmitted mainly by ingestion of the moldy feed, water or environment. The organism grows especially well on corn-based diet, so infection can be introduced easily by feeding stale feed. Crop Mycosis may also be "triggered" by the use of high levels of antibiotics in feed or drinking water for treatment of other bacterial diseases like CRD, Necrotic enteritis, colibacillosis etc. Continued use of antibacterial agents in poultry to prevent and treat increasing bacterial infections often causes secondary fungal infection, giving chance to mold spores appeared in the feed during transit and storage to colonize and multiply in the crops as feed stays longest in the crop (approximately 90-100 minutes). Birds/flocks who have been on antibiotics for a period of time are the easiest target of crop mycosis, fed on caked or stale feed.
This malady produces no specific symptoms. Young chicks become listless, pale, show ruffled feathers and appear unthrifty. Affected caged layer hens become obese and anemic. Clinical signs include dull and depressed look, reduced feed intake, poor growth often with large fluid filled crops and foul smelling odor emitted around the mouth. Profuse diarrhea may be noted. Losses are due to reduced feed efficiency, increased mortality (from 5%-20%), poor performance and stunted growth. Some birds also exhibit a vent inflammation that resembles a diarrhea-induced condition having whitish incrustations of the feathers and skin around the area. Feed consumption may increase by ten to twenty percent.
Diagnosis is based upon clinical signs and relevant history. Gross lesions are mostly confined to the crop, proventriculus and gizzard. The crop and proventriculus have whitish thickened areas that are often described as having a "turkish towel" appearance. Erosion of the lining of the proventriculus and gizzard is commonly observed, as well as an inflammation of the intestines. Mycotic lesions in young poults and chicks may be so small as to be easily over- looked during postmortem examination. Additional tests such as crop histopathology or microscopic examination of crop smears (mixed with KOH 10% and heated) will diagnose if Fungi is the cause however are rarely done due to time and financial constraints.
Once introduced into the flock, mold/yeast is perpetuated by suboptimal management conditions. Preventative measures include the continual use of a feed preservative & mold inhibitors in the feed, proper feed handling and storage, daily cleaning and sanitizing of the watering system.
Although improved broiler performance is an advantage for pellet feeding, some disadvantages seem to be connected to feeding poor quality pellets to the birds. With respect to immunity and animal health, a correlation between poor quality pellet feeding with lots of fines in it and the occurrence of certain diseases cannot be ignored. Nutritionist plays an important role in poultry industry to achieve the genetic potential of these hyper performing birds. As the industry has always been working from a feed formulation perspective, Nutritionist's and feed manufacturers spend much time and effort in evaluating the formulation and feed additives but not the final pellet quality.
It is important to realize here that feeding low quality pellets or crumble to the "new and improved" poultry can potentially do irreversible damage. Since poultry have the highest rate of gain early in life, they need nutrient-dense diets that support the rapid growth rate without challenging their health status. Feeding for least cost without focusing quality of crumbles and pellet in the first two weeks can result in lost performance that is never regained.
Not only is a proper nutritional program critical, but also a strong quality control program is a must to assure that quality ingredients are received and high-quality feed produced. This is as important for macro-ingredients such as corn, soybean, fat and animal proteins sources as it is for micro-ingredients such as vitamins, amino acids, enzymes and trace minerals. It is also crucial to ensure that the feed mill delivers durable pellets and crumbles with a minimum amount of fines to encourage feed consumption. Properly formulated feeds are worthless if birds do not eat the feed as a complete meal packet (a pellet or crumble). Finally, as the number of disease outbreaks are on rise and use of antibiotics for bacterial challenges is becoming limited, it is important for the vets as well to explore alternative options to keep the feed fresh and pathogen free to offset disease challenges.
Feed formulation no doubt is the focus point of this business, but raw material handling and feed processing plays a huge part on feed quality, and hence the performance & bottom line. A correct and pro-active approach will help save the industry much monies from unnecessary wastage from raw material quality, contamination, the unnecessary use of feed additives, over-formulation to compensate for the nutrient loss in feed processing and post processing quality issues, plus the avoidable use of medications at farm level. Controlling water activity (aw) values of the poultry feed, within safer limit, could be an extremely important consideration, in order to produce a safe and hygienic feed that is both commercially viable and plays an effective role in the physical, chemical and biological stability of the product.
Our Suggestion for Feed Millers:
Take time out to evaluate your feed mill running parameters and final pellet quality. If not happy with the outputs and quality, you must seek outside guidance, as the damage is huge because of poor feed processing and pelleting on the bird's performance as well as immunity & health aspects. Our suggestion, particularly to tropical feed millers during feed processing is to elaborate more on followings:
- Need to swell and cook raw starch well to gelatinize enough
- Must hydrolyze the mash sufficiently and effectively before it enters the pellet press
- Must think of minimizing losses of valuable micronutrients and enzymes; steer clear of Maillard reaction -
All the above points will positively impact feed production efficiency; productivity and the overall processed feed quality (nutrient value & feeding value). And please don't think that feed processing is a simple issue concerning loss or gain in moisture (production shrink or gain) only. You need to look at the bigger picture. This is the only way to break through mindset and barriers. Feed mills, particularly from tropics, need to understand the importance of addressing fundamentals of feed processing correctly, to face tomorrow's challenges.
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Article made possible through the contribution of Dr. Naveen Kumar and Delst Asia