In recent years, the research on the best pulverization particle size of different livestock feed materials has attracted great attention from animal husbandry workers. At present, there have been many reports on scientific and technological publications on the issue of accurately regulating the pulverization size of feed ingredients to achieve optimal livestock performance. Therefore, the article summarizes some of the current valuable research materials, hoping to provide readers with some relevant basic knowledge, so that readers can understand the current research progress and future development trends of this issue.
First, a brief review of the reasons for moderately reducing the particle size of feed ingredients. Advantages of raw material crushing:
1) Make some roots tubers or raw materials with high fiber content easy to process.
2) Improve the mixing uniformity.
3) Prepare for subsequent processing steps such as granulation or puffing.
4) Improve feed digestibility by increasing the contact area with digestive enzymes. 5) Cater to consumer preferences.
The American Society of Agricultural Engineers (1968) uses a method for evaluating particle size by a lognormal distribution proposed by Headley et al., which calculates the average particle size, geometric standard deviation, and particle surface area by measuring the ratio of feed ingredients through a standard sieve. The American Institute of Dairy Science (1970) also adopted this set of evaluation methods. The application of this evaluation method greatly facilitates the interaction between zoologists, nutritionists and feed enterprises, because this method is to compare the different crushing processes of raw materials and evaluate the effect of crushing size on the production of livestock. Etc. provides a unified standard.
1 livestock production performance
At present, the research content in this field is mainly focused on the nutrition aspect of pigs, but the discussion on the mechanism of particle size on production performance is not limited to pigs. The effect of particle size on feed utilization depends not only on the type of feedstock, but also on the growth stage of the livestock. Compared to adult livestock, younger animals chew their food more thoroughly, so the crushing size of adult pig diets does not have to meet the recommended standards. Tests have also shown that reducing the size of the pulverization can improve the performance of the animal without considering the age factor. In the study on the effect of granule granulation on the digestibility of finishing pigs in the diet, the sorghum was pulverized by a hammer mill after drying by drum drying and drying, using a standard sieve with a pore diameter of 6.4 and 3.2 mnl, respectively. The granules with an average particle size of 1,262, 802 and 471 gamma were subjected to a digestion test on finishing pigs equipped with ileal fistulas. The results of the apparent digestibility of the ileal end and the whole digestive tract chyme showed that reducing the smashing particle size of sorghum significantly increased the apparent digestibility of dry matter, carbohydrates, energy and nitrogen (see Table 1).
Ohh et al. used two different sizes of corn and sorghum to feed piglets using a drum mill and a hammer mill. During the processing, the drum mill grinds two kinds of coarse and fine corn and sorghum, and the hammer mill is equipped with 6.4 and 3.2 mm sieves for crushing. From Table 2, drum crushing The average particle size of the raw material after fine pulverization was similar to that of the hammer mill equipped with a 6.4 mm sieve. However, the geometric standard deviation of the crushing particle size of the drum mill is smaller than that of the hammer mill, and the generated dust (particles having a particle size smaller than 145 swollen) is also less. The effects of grain type, processing method and particle size on piglet performance in the feeding trial are shown in Table 3. Among them, the average daily increase quality is not affected by these three factors; but as the particle size increases, the feed intake of piglets is improved; compared with the hammer mill, the grain processed by the drum mill is also improved. The food intake; the lowest feed intake is the corn and sorghum processed by the hammer mill with 3.2 mm sieve. At the same time, the two cereals have the highest dust rate. The test results show that the fine grain is processed. Poor palatability to piglets.
The results showed that reduced grain size increased feed utilization (P < 0.05) and improved dry matter, nitrogen and energy digestibility (see Tables 4 and 5). The test verifies that previous studies on reducing feed particle size will increase the digestibility of nutrients may be partly due to the fact that fine pulverization can increase the amount of feed granules and increase the activity of digestive enzymes by increasing the effective area of ​​contact with digestive enzymes. .
It has been confirmed that the fine pulverization of feed can improve the production performance of livestock, but excessive pulverization also reduces the palatability of feed. Studies have shown that excessive smashing of feed increases the incidence of gastric ulcers in livestock. For fattening pigs with shorter feeding cycles, this problem has little effect, but the impact on breeding pigs is more serious.
From a management point of view, excessive smashing of grain during processing can produce a large amount of dust, causing excessive lung inhalation or eye irritation. At the same time, excessive comminution can also cause feed arching in the feeder and storage bin.
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