1 Feed crushing particle size and uniformity
1.1 Crushing particle size It is reported that when the grain size of weaned piglets is reduced from 900μm to 500μm, the increase in processing cost of the diet is less than the compensation caused by the increase in feed conversion ratio. When the size of corn granules in growing pigs was changed from 509μm to 1026μm, there was no significant effect on the daily weight gain of pigs. However, with the decrease of particle size, the feed conversion rate increased, and the optimal particle size range was 509μm. ~645μm. When the pulverized size of corn in the finishing pig diet is between 400 μm and 1200 μm, the feed conversion rate is increased by 1.3% for every 100 μm reduction in grain size. When the pulverization size of corn was reduced from 1200μm to 400μm, the feed intake and digestible energy intake of the lactating sow, the dry matter of the diet, the digestibility of energy and nitrogen, and the litter weight gain of the piglets increased. The dry matter and nitrogen in the feces The content was reduced by 21% and 31%, respectively. When the size of corn in the simple diet was reduced from 1000μm to 500μm, the daily weight gain of piglets was significantly increased, while the daily weight gain of pigs composing complex diets was less affected by the crushing size of corn. The appropriate size of the feed pulverization of the piglets from 0 to 14 days and from 14 days to 35 days after weaning is 300 μm and 500 μm; the growth and finishing pigs and the sows are 500 μm to 600 μm and 400 μm to 600 μm, respectively.
1.2 Crushing uniformity The roller mill has higher uniformity of crushing than the hammer mill. The conversion rate and growth rate of wheat when pulverized by a roller mill are higher than those of a hammer mill. When the pulverization uniformity of corn is increased, the performance of finishing pigs is not affected, the digestibility of dry matter, nitrogen and total energy of the diet tends to increase, and the dry matter discharge of the manure is reduced; the corn is crushed by a roller mill, which is smaller than the hammer. The pulverizer can increase the nutrient digestibility in the diet and reduce the dry matter in the manure by 19% and the nitrogen emission by 12%.
2 Mixing Uniformity
According to reports, when the variation coefficient of feed uniformity of piglets decreased from 106.5% to 12.3%, the daily gain and feed conversion rate increased by 32.5% and 19.2%, respectively, while the coefficient of variation of feed uniformity in finishing pigs was 53.8%. When it fell to 14.8%, there was no significant improvement in production performance. Therefore, the uniformity of diet mixing has a greater impact on young animals and when feeding non-full-price diets. Therefore, the suitable coefficient of variation for the uniformity of feed for piglets is 12%; the coefficient of variation for feed mixing uniformity of finishing pigs is at least 15%.
3 granulation
Because the pellets have many advantages over the powder, they are widely used in the production of weaned piglets. The granulation of raw soybean powder significantly reduced the content of trypsin inhibitor. Feeding pigs and sows with corn or sorghum powder, the feed conversion ratio, total energy apparent digestibility and nitrogen digestibility of the pellets were significantly higher than that of the powder, and there was no significant difference in weight gain. It has been reported that the average daily gain and feed conversion rate of pigs fed pellets before 5 days of age increased by 25% and 36%, respectively, and the particle diameter (2mm~12mm) did not affect the growth performance of pigs; The daily weight gain and feed conversion rate of pigs with a diameter of 4 mm during the 29-day-old age were the highest; the growth rate of pigs in the 29-day-finishing period was not affected by the feed form, but the feed conversion ratio of the pellets was better. Powder. It has also been reported that when feeding sifted granules to piglets, the feed conversion rate is 4.5% higher than that of pellets containing 15% or 30% fine powder; in finishing feed for fattening pigs, the ratio of fine powder to granules is 0 increased to 60%, the feed conversion rate decreased, and there was no significant difference between daily gain and nitrogen digestibility and backfat thickness.
Although granulation has advantages, retinol, vitamin K, ascorbic acid, carotene, vitamin E, and thiamine are more sensitive to granulation. Studies have shown that the granulation temperature at 75 ° C and 95 ° C can reduce the activity of β-glucanase by 40% and 70%, respectively, and the loss of β-glucanase and cellulase activity is more than 110 ° C; When the granule temperature was 79 °C, the phytase activity decreased by 45.8%, and at 80 °C, it decreased by 87.5%, and the activity loss was large.
4 Expansion and ripening and extrusion of
Compared with granulation, expansion maturation and extrusion have the characteristics of short time, high temperature and high pressure. The expanded material has better palatability and higher utilization than the granular material. Puffing processing is more effective than granulation in controlling Salmonella.
When the whole fat soybean is expanded, it does not affect the lysine content, and significantly reduces the trypsin inhibitor content and the protein dispersion index. In the diet of finishing pigs based on corn, sorghum or wheat meal, the digestibility of nutrients can be improved by expansion processing, but in wheat-based diets, the digestibility of nutrients is not processed by expansion. The improvement is that the wheat flour with higher crude fiber content than corn or the sorghum with lower value than corn has higher nutrient value than corn after expansion processing.
For piglet diet puffing + granulation or expansion + granulation, the daily weight gain, feed conversion rate and energy and protein digestibility of pigs were improved compared with granulation only. Pigs in the 8kg ~ 12kg, 10kg ~ 35kg and 35kg ~ 110kg weight stage, eating expanded pellets, feed conversion rate is better than the consumption of ordinary quenched and tempered pellets. Some people have studied the effects of powder, ordinary granular materials, expanded materials, expanded granular materials and expanded granular materials on pig production performance and nutrient digestibility. In terms of improving weight gain and feed conversion rate, piglets and growing pigs are generally eaten. The effect of pellets is better than that of expanded pellets; the effect of growing and finishing pigs on ordinary pellets is better than that of expanded pellets; while the effect of piglets on ordinary pellets is inferior to that of expanded or expanded pellets; expansion or expansion When the grain processing is combined, there is no additive effect on the digestibility; the expansion or expansion process of the diet, compared with the improvement of the production performance of the powder and the pellets, seems to increase with the decrease of pig age. That is, as the age of the pig increases, the grain processing of the diet is sufficient to optimize the production performance. The effect of swelling and puffing on pig performance is also related to the nature of the diet. Expanded and expanded fibrous diets have a greater effect on improving pig performance than treatments with highly digestible or corn-soybean meal. Expansion and expansion process have a great impact on the stability of vitamins in feed. The growing pigs were fed with vitamin diet before puffing, and the growth rate and feed conversion rate were lower than those of the vitamin group after puffing.
In summary, appropriate processing of the feed can increase the nutritional value of the feed and the performance of the pig to varying degrees, potentially reducing the environmental pollution of livestock and poultry excrement. Although thermal processing has many advantages, it increases the processing cost, reduces the stability of vitamins and the activity of enzymes. When applying, it should weigh the pros and cons and make decisions.
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