Feed manufacturing results in physicochemical changes in the raw materials, which may have starch gelatinization. The effect of gelatinized starch on animal performance has not been determined in previous studies. Broiler feeds usually contain a high percentage of cereals, so there is a lot of starch. When heated with water, the starch gelatinizes and binds the comminuted feed together (Mommer and Ballantyne, 1991). Previous studies have investigated the effects of gelatinized starch in diets on pellet quality and broiler performance, both positive and negative (Moritz et al., 2001, Moritz et al., 2002a, Moritz et al., 2002b). However, it has been speculated that in addition to the role of bound particles, gelatinized starch may also have an impact on broiler performance.
It is generally accepted that gelatinization of cereal starch helps the enzyme to contact the glycosidic bond to promote digestion (Moran, 1989, Colonna et al, 1992). Allred et al. (1957) reported that chickens fed granulated and comminuted corn were fed to full-price rations, and the corresponding weight gain and feed conversion ratios were significantly improved over the same diets prepared with unprocessed corn. However, subsequent studies determined the diet of this granulated, comminuted corn, and concluded that there was no nutritional advantage for broilers other than increased starch gelatinization of the diet (Sloan et al., 1971, Naber and Touchburn, 1969). Moreover, Plavnik et al. (1997) found that broilers fed rations made from granulated, comminuted corn produced poorer performance than broilers fed the same unprocessed diet. Making the starch in the raw material as much as possible has always been a principle for producing high quality pelleted feed. However, increasing the quality of the granules by promoting starch gelatinization may have a negative effect on nutrient utilization, which would offset the granulation promoting effect on animal performance.
The study was to process corn in the usual way of production, replacing raw corn in a different ratio to prepare a complete diet, with the aim of making several diets containing gelatinized starch in varying proportions from different commercial processing methods. Corn is used as the sole processing material in order to avoid confusion caused by high fat or high protein materials being processed. The corn is granulated or extruded prior to formulation and comminuted again. The percentage of starch gelatinization provided by granulated corn represents the condition of conventional granulated feed, which provides a very high percentage of gelatinization levels. These feeds were used to feed broilers of 0 and 3 weeks old chicks to investigate the effect of processing gelatinization on production performance.
The similarity of the bulk density of unprocessed corn and processed corn after comminution is important because the starch concentration of the diet affects the feed intake of broilers (Naber and Touchburn, 1969). Dietary water content relative to nutrient concentrations also affects feed intake (Moritz et al., 2001, Moritz et al., 2002a). However, the moisture content of several types of corn is similar, and corn is not the only raw material that determines the moisture content of the diet. Although both the unprocessed and processed corn are comminuted by the same hammer mill screen, the particle sizes are still different, but the standard deviation between the different particle sizes is similar. The percentage of starch gelatinization was calculated relative to unprocessed corn, and the starch gelatinization rate of granulated corn and extruded corn was increased to 29% and 92%, respectively. The percentage of gelatinized starch in diets containing 3/3 granulated corn was similar to that of 1/3 extruded corn. The gelatinization peak temperatures of several corns are similar. There is no significant interaction between the type of corn processing and the proportion in the diet. Broilers fed granulated corn diets had lower feed intake and higher feed efficiency than those fed squeezed corn diets. Broiler live weight growth and mortality are not affected by the type of corn processing. The difference in particle size between corn types may explain the difference in production performance described above. Studies have shown that corn grain size in powder diets affects feed preferences, weight gain, growth efficiency, and metabolic status in broilers (Portella et al., 1988, Healy, 1992; Nir et al., 1994, Nir et al., 1994). The granulated corn size of our study was 231 μm smaller than that of extruded corn. Healy (1992) found that the grain size of dietary grain waxy corn, hard sorghum or soft sorghum was reduced from 900 μm to 300 μm at intervals of 200 μm, and the feed efficiency of 0-3 weeks old broilers increased linearly (P=0.001). In the case of corn-based diets, improved feed efficiency was associated with reduced feed intake and increased nitrogen-corrected metabolizing energy in broilers, but Healy (1992) did not separately report broiler performance on various cereals. analysis. Wondra et al. (1995) argued that reducing the particle size increases the surface area and makes nutrients more accessible to digestive enzymes.
Nir et al. (1994b) observed that feed broilers fed a 900 μm corn diet showed significant increases in feed efficiency and live weight during 1-3 weeks of age compared to broilers fed a diet containing 1 000 μm or 2 000 μm corn. improve. The authors speculate that these differences may be due to changes in the gastrointestinal tract. Nir et al. (1994c) found in subsequent studies that broilers fed coarse grain (2 000 μm corn, wheat or sorghum) had a 21-day-old muscle stomach weight compared to broilers fed the same grain of 600 μm or 1000 μm. Larger (P = 0.01). Similarly, Healy (1992) observed that broilers fed 900 μm grain were heavier in the stomach and gland than in the 300 μm grain. Nir et al (1994c) suggest that physiological changes in the gastrointestinal tract may affect the appetite and feed rate of broilers. Healy (1992) speculated that the weight of the gastrointestinal organs may affect the maintenance energy needs of broilers.
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