Effect of different ring die compression ratios on feed milling rate of Penaeus vannamei——results and analysis

Analysis of the results of pellets with four ring die compression ratio

The powdering rate of P. vannamei produced by the compression ratios of 4 ring molds is shown in Table 1

The results show that when the ring membrane compression ratios are 1:20 and 1:22, the chalking rates are as high as 4.72% and 3.60%. When the compression ratio of the ring membrane is 1:24 and 1:26, the powdering rate is as high as 2.64% and 0.92%. As the compression ratio of the annular membrane increased from 1:20 to 1:26, the feed milling rate decreased from 4.72% to 0.92%. For each reduction of the ring membrane compression ratio, the feed powdering rate increased to 1.3% on average. In addition, the differences in feed milling rates of P. vannamei produced by the four types of ring membrane compression ratios were significant (P≤0.05). Among them, the compression ratio of the ring membrane is 1:20, and the pulverization rate is the highest, reaching 4.72%; while the compression ratio of the ring membrane is 1:26, the pulverization rate is the lowest, only 0.92%.

What are the factors that affect the feed powdering rate

There are many factors that affect the feed powdering rate, among which the formula structure, raw material crushing particle size, ring membrane, quenching and tempering, and Post curing are the key factors. If the content of fat and protein fiber in the formula is too high, the feed will become loose, and the increase in starch content will increase the firmness of the feed.

What are the factors that affect the feed powdering rate

In actual production, the compression ratio of the ring membrane is an important factor that can be easily overlooked. In particular, in order to reduce the production cost, the ring membrane is repeatedly repaired and used. Although the benefits are considerable, the worn part must be cut off every time the single ring membrane is repaired. It is reprocessed into a horn hole, which results in shortening the effective hole length, which reduces the compression ratio of the ring membrane, and the pulverization rate of the feed changes accordingly, which seriously affects the quality of the product.

At present, the national standard for feed powdering rate of Chinese shrimp is ≤3%. From the test results, when the ring membrane compression ratio is 1:20 and 1:22, the feed powdering rate of P. vannamei produced does not meet the relevant national requirements (SCT2002 -2002), this may be because the samples in this experiment were all taken at the sampling port after treatment, without processing steps such as post-cure, the feed did not get further gelatinization, and the firmness was slightly insufficient, so the flouring rate Will be slightly higher than the finished feed. When the 1:26 compression ratio ring membrane is used, the feed powdering rate is less than 1%. If it is difficult to granulate the formula, a ring membrane with a lower compression ratio can be appropriately selected, and the ideal effect can also be achieved. It is known from the test results that the ring membrane compression ratio of P. vannamei shrimp feed is 1: 22 ~ 1: 26.