Study on the effect of particle size and Feed Form of raw material crusher on animals

Pulverized particle size refers to the particle size of finished materials after grinding raw materials, which is expressed by percentage of residue on screen method, hammer mill sieve hole diameter method, arithmetic mean particle size method, geometric mean particle size method (GMD), geometric mean particle size and lognormal geometric standard deviation method (Sgw), etc. The geometric mean particle size and logarithmic normal geometric standard deviation method are scientific. This method provides a unified standard for comparing different grinding processes of raw materials and evaluating the effects of grinding particle size on livestock production performance. Comminution size directly affects the nutritional value of feed, animal digestion and absorption, comminution cost, subsequent processing process and product quality. Different animal breeds, feeding stages and raw material composition have different requirements for feed crushing size and feed morphology. Now the widely used feed types mainly include powder, granular and expanded feed, etc., and the feed type has great influence on feed utilization rate and animal production performance.

1 effects of grinding size and feed type on nutrient composition of feed

The grinding size had little effect on the feed active ingredients, but the grinding could promote the gelatinization of starch, which was beneficial to the digestion and absorption of animals.

1.1 Effect of particle size of raw material on protein solubility

The results show that decreasing the particle size of raw material can increase the solubility of protein, which can reflect the digestibility of raw protein to a certain extent. Shen Huile et al. measured the protein solubility of soybean meal samples from different regions in China, and found that the protein solubility increased with the decrease of soybean meal size. Mi Zhenhai et al. studied the absorption rate of protein digestion by crushing particle size and showed that the absorption rate of protein digestion of 30-mesh fish meal was 27.79%. The digestibility of protein of fish meal from 90 to 100 mesh increased to 66.15%, indicating that superfine grinding of protein feed plays an important role in the digestion, digestion and absorption of protein and other nutrients. Li Qingxiao et al studied the relationship between different particle size of soybean meal and protein digestibility in vitro. The results showed that the digestibility of crude protein in 449μm group was higher than that in 2565, 529 and 334μm groups by 10.75%, 4.43% and 1.37%, respectively.

1.2 Influence of pulverized particle size of raw materials on digestibility

Woodsman et al. found earlier that milling oat could improve nutrient digestibility, and later studies confirmed that the nutrient digestibility of sorghum, barley, corn and wheat was improved after milling. Hancock et al reported that when the grain size of corn was reduced from 1200μm to 400μm, dry matter digestibility, nitrogen digestibility and nitrogen deposition rate of sows were increased by 7.18%, 9.67% and 3.77%, respectively, and digestible energy and metabolizable energy were increased by 1444.8 and 1 453.2 kJ/kg, respectively, indicating that, Proper comminution is beneficial to feed digestion. Peron et al. showed that starch digestibility and apparent metabolizable energy (AME) of fine milling wheat were increased to varying degrees compared with coarse milling. Wondra et al. conducted an experiment on finishing pigs by crushing corn with different grain size, and the results showed that when the grain size of corn was 0.4 ~ 1.2 mm, the feed conversion rate increased by 1.3% when the grain size decreased by 0.1mm.

1.3 Influence of feed type on nutrient composition

1.3.1 Effects of pelleting on nutrient composition of feed

Granulation can gelatinize starch, and the heating, hydration and shearing of granulation process can break the spatial structure of protein and better interact with digestive enzymes. Pelleting can completely inactivate the lipase secreted by microorganisms in feed raw materials, so as to no longer have effect on unsaturated fatty acids in feed, so as to improve the storage performance of feed. Moreover, due to cell rupture, oil soaked to the cell surface, improving the appearance and palatability of feed. Wondra et al. affected the performance of pigs by pellet feed. The results showed that the digestibility of DM and N increased by 5%-10%, and the excretion of DM and N decreased by 23% and 22%, respectively, reducing the environmental pollution.

1.3.2 Effects of extrusion on nutrient composition of feed

Extrusion is widely used in feed production because of its many advantages. During the extrusion process, the temperature can reach 90 ~ 200℃, and the duration is 10 ~ 30s. Therefore, the extrusion products will undergo a series of physical and chemical changes, such as starch gelatinization, protein denaturation and enzyme, toxic components and microorganism inactivation. This process improves the nutrient digestibility of feed, and destroys the role of heat-sensitive antinutritional factors, such as antitrypsin in soybean and gossypol in cottonseed. It also kills bacteria and mold in feed, reduces dust content and improves feed palatability. But high temperature processing will destroy the vitamins in the ingredients, so that its activity is reduced.

Effects of particle size and feed type on growth performance of animals

Although crushing has many advantages, excessive crushing needs to consume more electric energy, and will also cause dust flying, leading to animal respiratory diseases and environmental pollution, so the feed crushing size should be within a certain range. Pelleting and puffing can mature the feed, kill the bacteria in the feed, promote the digestion and absorption of the feed and improve the utilization rate of the feed, which should be promoted in the feed processing.

2.1 the poultry

Feed intake of poultry is related to feed size, pellet feed or crushed feed can increase feed intake. Lott et al. found that corn with larger grain size reduced the performance of broilers, and corn with grain size greater than 1100μm could not be utilized well by broilers. A M Amerah et al studied the feed type and raw material grinding size of wheat basal diet for broilers, and the results showed that the ratio of feed to gain of pellet and powder was 1.523 and 1.673 respectively, while the ratio of feed to gain of coarse grinding and moderate grinding was 1.575 and 1.621 respectively, indicating that the influence of feed type on feed to gain ratio was greater than that of grinding size. Wu Xiaobing studied the effects of four kinds of corn grain size (diameter 0.336, 0.585, 0.856 and 1.12mm) and two kinds of diet shape (powder and pellet) on broilers aged 21 to 42 days. The results showed that when corn grain size was 0.336mm, feed intake, daily gain weight and feed conversion rate in powder group were significantly lower than that in pellet group. Wang Weiguo et al. 's study showed that with the decrease of feed pulverized particle size (from 8mm to 5mm), the laying rate of laying hens increased from 59.9% to 61.9%, and the ratio of feed to egg decreased from 3.12 to 3, indicating that reducing the particle size had a positive effect on laying rate and ratio of feed to egg, but the difference was not significant.

Coarse particles can affect the performance of young poultry because of slow passage through the musculature or incomplete development of the musculature, which cannot break large particles. Particles larger than 1000μm are too large for broilers to be used effectively. Ravindran et al. showed that young chickens could hardly swallow whole grains of wheat in the first few days of their life. Broilers fed the whole grain wheat diet grew slower and had lower feed intake than those fed the pulverized wheat diet. Once the muscular stomach is well developed, feeding a rougher diet improves performance.

2.2 the pig

The effects of feed grain size on pig performance were mainly related to pig age, grain type and grain size. Sun Jian et al believed that grain size affected the performance of lactating sows. The grain size of corn was reduced from 1200μm to 400μm, the feed intake of sows was increased by 14%, and the litter weight was increased by 11%. Keuy et al. found that when the grain size of corn was 100-400 μm, the growth rate of pigs increased by 3% when the grain size decreased by 100μm. Therefore, proper comminding is an effective way to improve the growth performance of growing-finishing pigs. The results from university of Kansas showed that when the average grain size was between 400 μm and 1200μm, the feed rate increased by l % ~ 1.5% for every 100μm reduction of grain size. The study of Canadian scholars showed that when the feed particle size decreased from 950μm to 750μm, the daily weight gain of animals increased from 0.79kg to 0.96 kg.

Weaner piglets, especially early weaner piglets, due to the digestive function of intestines and stomach is not perfect, the grain in the diet is better to mature, puffing and granulation have this effect. Chen Quanjun et al. studied the effects of bulking, standard conditioning and granulation and untreated powder on the production performance of Duroc × Yorkshire × landrace commercial pigs within 7 days after weaning. The results showed that: The daily gain weight of the granulated material, extruded material and powder was 123, 76.6 and 79g, respectively. The daily gain weight of the granulated material group was 60.5% and 55.6% higher than that of the other groups, respectively, and the difference was extremely significant. There was no significant difference in the production performance between the extruded material and powder groups.

0ryschak et al. found that reducing the grain size of barley and pea diets increased the total apparent intestinal digestibility (CTTAD) of dry matter (DM), gross energy (GE), crude protein (CP) and digestible energy (DE). Healy et al. showed that when the particle size was reduced from 900μm to 300μm, the feed intake of weaned piglets decreased and the growth rate did not increase. J C Kim et al found that when grain size of wheat decreased from 920μm to 580μm, starch CTYAD of piglets was significantly increased, but CTI'AD of GE was not affected. Jiang Yu et al studied the effects of powder diet, extruded powder diet, pelleting diet and extruded pelleting diet on performance and nutrient digestibility of growing-finishing pigs. The results showed that the daily gain weight of extruded powder diet, pelleting diet and extruded pelleting diet was 3.98%, 1.49% and 8.96% higher than that of powder diet group, respectively. The feed utilization rate was improved by 8.35%, 6.08% and 13.42%, respectively. The apparent digestibility of crude protein increased by 3.94%, 2.29% and 1.68%, respectively. The results showed that the feeding effect of pellet feed was better than powder feed, and the additive effect of puffing or re-granulating diet was observed.

2.3 Ruminants

Li Jie et al. studied the effects of 4 different particle sizes of soybean meal on rumen fermentation and outflow rate of sheep. The results showed that different particle sizes of soybean meal had no significant effect on rumen fluid pH, and the rumen NH3-N mass concentration tended to decrease with the increase of soybean meal size. The rumen decomposition rate of fine crushed soybean meal was faster than that of coarse crushed and uncrushed soybean meal, and the mass concentration of NH3-N in uncrushed soybean meal group was 10.35% to 15.6% lower than that in other groups after 6h feeding. In the experiment conducted by Ma Wenjian et al., it was found that adding coarse and fine ground soybeans to beef cattle did not significantly affect the intake, slaughter rate, net meat rate, high-grade meat yield and high-grade meat percentage of beef cattle with different processing particle sizes. Zhang Yuanqing et al showed that the grain size of corn or wheat in the growing steers diet significantly affected the chewing time of animals, and feeding the whole grain led to the decline in the growth performance of steers. Dong Ying study found that for 7 ~ 9 months of age young corn milk goats fed different particle size, and the coarse crushing (2.57 mm), and compared the whole grain of corn, fine crushing corn (0.76 mm) to improve the rumen ventral sacs nipple height, coarse grinding corn group compared with whole grain or fine crushing corn group, abomasum displacement, the quality of small intestinal mucosa and the trend of the large intestine length were increased, The apparent digestibility of starch in whole corn group was decreased.

2.4 Aquatic animals

Cedric J Simon reduced the pulverized size of fish meal from 500μm to 106μm and found no significant effect on feed digestibility of lobsters. However, studies by L G Obaldo et al showed that the reduction of raw material particle size could improve the dietary digestibility and feed conversion rate of river shrimp. Sales and Britz reported that dietary digestibility of South African abalone was improved by reducing the granularity of raw material from 450 ~ l000μm to less than 450μm.

Effects of particle size and material type on animal digestive tract

The results showed that the development of digestive tract (especially musculostoma) in poultry was affected by feed size, and rougher feed was beneficial to the development of digestive tract. Talor et al. found that compared with fine grain, 7-day-old chickens fed medium and coarse grain had larger musculogastric development and lower pH, while broilers fed fine pulverized diet had poorer musculogastric development and enlarged anterior stomach. When the feed is pulverized too fine, the degree of keratinization in pig gastrointestinal tract can be significantly increased. Wondra et al. studied the effect of feed grain size on gastrointestinal ulcer index of pigs. When the pulverized grain size decreased from L000 μm to 400μm, gastrointestinal keratinization degree and gastrointestinal damage degree of growing-finishing pigs were significantly increased. Corn grain size decreased from 800μm to 400μm, gastrointestinal ulcer index of powder group increased from 0.1 to 0.9, an increase of nearly 9 times. There was no change in ulcer index in pellet group.

Researchers from Danish Academy of Agricultural Sciences believed that feed structure was related to feed particle size and raw material type, and had a significant effect on pathogenic bacteria in pig digestive tract, especially salmonella. Studies have shown that feed pelleting can increase the risk of salmonella infection, and feeding coarse crushed feed can reduce the prevalence of salmonella in the intestinal tract of pigs than feeding fine crushed feed. M S Hedemann et al found that the length of villi in the small intestine of pigs fed coarse pulverized non-granulated diet increased by 85μ M compared with pigs fed coarse pulverized granular diet. Feeding coarse pulverized diet also increased the depth of colonic crypt (fine pulverized (420±12)μ M and coarse pulverized (449±12)μ M). G Brunsgaard et al. showed that intestinal epithelial cell proliferation rate of pigs fed coarse grain barley was faster than that of other diets (coarse grain wheat, fine grain barley and fine grain wheat), and feeding coarse grain crushed diet effectively prevented intestinal infection.

4. Effects of particle size and feed type on digestive enzyme activity and exogenous enzyme preparation

There are few studies on the effect of particle size of raw material on enzyme activity in animal digestive tract. There are two hypotheses to be confirmed about the relationship between the comminution size and digestive enzyme activity: 1) The different comminution size leads to the difference in gastric emptying speed, the difference in the speed and quantity of digesta entering the small intestine, and the difference in the quantity of digestive enzyme secretion. Medium crushed particles than coarse crushed particles, fine crushed particles have good fluidity, can quickly through the stomach into the small intestine, so that the pancreas rapidly secreted a large number of digestive enzymes in a short time; 2) Feeding different grain size feeds for a long time may have some influence on the development of digestive tract, and may also affect the secretion of pancreatic juice, resulting in the difference of digestive enzyme activity. J C Kim et al. found that the CTTAD of crude protein increased from 0.72 to 0.74 after xylanase and glucanase were added to the 920μm wheat diet, while the CTFAD of crude protein increased from 0.71 to 0.75 after the same enzyme preparation was added to the 580μm wheat diet, indicating that the grinding grain size decreased

The contact area between feed and enzyme preparation was increased, which was beneficial for enzyme preparation to play a role. Blasel et al. showed that the effect of A-amylase was related to grain size to a certain extent, and the degradation amount of starch per kg decreased by 26.8 g when the grain size of corn was increased by 100μm. The results showed that the total protease activity of jejunum contents of broilers fed diets containing different pulverized soybean meal was 449μm>334μm>529 μm>210 μm from high to low.

5 subtotal

The grinding size and feed morphology of feed should be evaluated comprehensively according to animal species, growth stage, grain type and processing technology. Powdery feed can increase the contact area of digestive enzymes and nutrients, while the feed with large particles can increase the residence time in the digestive tract. Within a certain range, the finer the particle size of the material is, the better the pelleting effect is, and it is easier for animals to digest and absorb, thus improving the nutritional value of feed and the production performance of animals. However, there are also some adverse factors, such as: the cost of feed production increases, some nutrients, especially amino acids and vitamins, are lost due to processing. Therefore, the effects of feed type and pulverized particle size on animal performance, digestive tract development and nutrient utilization rate need to be further studied, so as to achieve more rational utilization of feed resources and improve the overall economy