Broiler Production is one of the agricultural production segments to have experienced the greatest changes over recent decades. This development has been brought about by market growth and the huge progress that has been made in production performance and efficiency. The primary objective is to reach the targeted slaughter weight within a minimal growth period while considering flock uniformity, animal welfare and environmental issues. Productivity mainly depends on the feed intake and production performance of the birds, and can be optimized by adapting the feed form and particle size
Common feed forms in animal feed are pellets, crumbles or mash. However, in the broiler industry, pellets and crumbles are mainly used. In less intensive areas, mash production for broilers is common too. Furthermore, the size of the single particles is a crucial factor that influences bird performance and health, independent of the feed form.
Processing of feed in uniform durable pellets affords significant benefits; the increased bulk density reduces the segregation and dustiness of the feed, thereby reducing losses. Feed conversion efficiency is much improved because it results in less feed spillage during consumption. Pelleting also maintains the integrity of the gastrointestinal tract and the heat treatment associated with pelleting improves feed digestibility by deactivating anti-nutritional factors and hence improves performance.
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Although the feeding behavior of birds can be challenging to take into account in feed production, it also provides an opportunity to control feed intake. Pelleted broiler feed has various advantages such as decreased feed wastage and improved feed hygiene. However, the most important difference compared with mash feeds is increased feed intake.
Chickens prefer to pick coarse particles, and this is observed at all ages. Regarding feed intake, one pellet is equal to one particle, regardless of the size. This fact has different consequences:
1. Broilers receive more energy and nutrients at the same time when fed with pellets. Because feed intake is time-limited, this is an important factor to consider when maximizing feed intake, especially in young birds.
2. Chickens choose particles by form, color, size and consistency. A more uniform diet and a narrower range of particle sizes reduce the time spent searching for and selecting larger particles.
3. Preferred particles, such as coarse corn, cannot be segregated in pellets like they can in mash. This results in a more balanced supply of nutrients because sufficient intake can be ensured, including minor components such as additives with a different density, like minerals (heavy) or fibrous components (light).
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Due to the higher feed intake, performance is increased when animals are fed pellets compared with mash feeding which explains why the majority of broiler feed is pelletized. Therefore, it is also necessary to compare the different pellet qualities which are measured in percentage of fines. Performance is the same in broilers fed with poor-quality pellets as those fed with mash. Feed intake, body weight gain and feed efficiency are lower compared with broilers fed with high-quality pellets especially at later ages. In terms of pellet quality, it is important to differentiate between evaluations carried out at the feed mill and those carried out before consumption as, during transportation and handling, frictional forces decrease the quality of the pellets. The provision of high-quality pelleted feed is essential to achieve maximum feed intake and high animal performance.
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Part of the beneficial effect of pelleting is due to an increase in metabolisable Energy (ME) value (Table 1) with resulting improvements in weight gain and feed/gain ratio. With wheat bran and shorts, most of the improvement from pelleting can be attributed to the increase in bulk density of the feed with a lesser amount of time and energy being expended for prehension, as well as the increased availability of the contents of the aleurone layer of cells. In the case of wheat middlings, the pelleting caused no significant increase in ME but did result in a marked improvement in feed intake and in performance. The increased feed intake was not due to a change in bulk density but to an alteration in the middlings that prevented beak pasting and necrosis, which occurs with the unprocessed wheat middlings.
There is also an increase of protein utilization and amino acid absorption with pelleting even when the feed pellets are reground to the consistency of mash (Table 2). Such improvement, however, was noted mainly for wheat bran and wheat germ but not for cereal grains, and can be attributed almost entirely to the destruction of heat-labile toxic factors that impair digestion and utilization of protein.
Pelleting maintains the normal structure and function of the gastrointestinal tract. The gizzards of birds fed pelleted rations were better developed compared with other birds whose gizzards were atrophied when fed ground rations since they had no hard particles to grind down. The well- developed gizzard can be regarded as a barrier in preventing pathogenic bacteria from entering the distal GIT. Studies have also shown that the small intestine was better integrated with pellet diets compared to the mash diet. Pelleting increases the villous height due to the physical stimulation of the villi and hence increases the absorptive capacity of the small intestine. It also reduces the thickness of the muscular layer lining the small intestines thereby allowing greater contact between the nutrients and villi.
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Offering pelleted feed to broilers can result in a 67% reduction in the energy required for eating, and hence directing such an amount of energy towards productive purposes. Shown in Table 3 are results of 3 experiments comparing the performance of broiler chicks fed pelleted and ground rations.
These experiments were conducted on the same breed of chickens under similar management conditions. The differences in feed conversion observed within the pelleting treatment could have been linked with differences in pellet quality. It has been estimated that 0.01 in feed conversion is lost with each 10% increase in ‘fines’ in pelleted feeds. Although pellet quality may appear adequate immediately after leaving the feed mill, pellet quality at the time the flock is consuming the feed in the house is what counts. Every effort should, therefore, be directed toward improving the quality of pellets that arrive in the feed troughs for broilers.
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• Decreased feed wastage
• Reduced dustiness and increased palatability thus making for greater consumption
• Reduced storage spaces
• Increased utilization of fibrous fraction of feedstuffs
• Adaptable to bulk and mechanized feeding
• Allows partial gelatinization of starch and modification of the protein in grains making them more susceptible to enzymatic action and better digestion.
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In addition to feed form, the particle size of the raw materials in the pellets also has an influence as the pellets dissolve in the crop. The reason is that the gizzard of broilers has the same function as a roller mill, grinding the feed into smaller particles. Coarse particles in the feed stimulate gizzard activity, which results in improved grinding and gizzard development, as well as longer residence times, increased stimulation of digestion and improved body weight gain.
In contrast, fine particles cause diverse health issues, such as poor gut motility, swollen proventriculus, poor water and electrolyte reabsorption, increased feather picking or increased susceptibility to enteric pathogens. However, apparent nutrient digestibility values can be positively affected by reduced feed particle size, whereas apparent metabolizable energy was not affected.
Ileal starch digestibility values were 95% to 98% for corn, demonstrating that the differences were minor. Taking all aspects into account, with the exception of younger birds, a coarse particle size in broiler feed provides greater benefits in terms of performance and health.
For young birds, on the other hand, finer granulation is required, due to their still underdeveloped digestive system. Therefore, it is reasonable to increase the preparation of nutrients and reduce the particle size in order to improve nutrient absorption in young animals.
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One of the most important factors that determine feed utilization by chickens is the feed form. Although it is generally believed that pellet diets have a positive effect on chicken growth, there are some studies that have indicated no difference between pellet and mash on chickens performance. This study was conducted to assess the effects of feed form on production performance, egg quality, nutrient metabolism and intestinal morphology in two breed laying hens. Two hundred and sixteen 25-week-old Hy-Line brown (n = 108) and Hy-Line grey (n = 108) hens were selected. Each breed was randomly allocated into two treatments with 6 replications (9 birds in each replication), which were fed mash and pellet diets, respectively.
Production performances were recorded daily and egg quality traits were measured every two weeks. At 42 weeks of age, one bird per replication from each experimental group was selected for metabolism determination and intestine morphology observation. Compared with mash diets, pellet diets improved laying rate (p < 0.05), ADFI (average daily feed intake, p < 0.05), egg weight, shell strength, yolk proportion and Haugh unit (p < 0.05) in both breeds and reduced the FCR (feed conversion ratio, p < 0.05) in Hy-Line grey. The apparent digestibility of DM% (dry matter) and CP% (crude protein) were significantly higher (p < 0.05) in both breed laying hens fed pellet than those fed mash. The apparent digestibility of P% (phosphorus) and Ca% (calcium) was higher in Hy-Line grey fed pellet and was higher in Hy-Line brown fed mash. Compared to mash diets, pellet diets increased the VH (villus height), CD (crypt depth) and VCR (ratio of villus height to crypt depth) of the small intestine of Hy-Line grey, and increased the VH and CD of duodenum and ileum of Hy-Line brown. Overall, pellet diets improved production performance and nutrition metabolism through positive changes in the laying rate, feed intake, egg albumen quality and apparent digestibility of laying hens. The current findings provided support for the advantages of feeding pellets during the peak egg laying period for the two popular laying hen strains, Hy-Line brown and Hy-Line grey.
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Refrences:
Effect of the Pellet and Mash Feed Forms on the Productive Performance, Egg Quality, Nutrient Metabolism, and Intestinal Morphology of Two Laying Hen Breeds, animals 2021
