Variation Pattern Of Feed Mildew And Quality Changes Under Different Fat Level And Moisture Condition

This paper explored the connection between mildew and fat content and type in feed. Meanwhile, the effect of fat constitution on mould growth,quality change and aflatoxin B1(AFB1) contamination differences in corn and soybean meal feed were investigated.Methods:1. Study of mildew pattern in feed with different fat level:we mixed compound feed, which containing corn, soybean meal and wheat bran as basic ingredient, with4%,6%,8%,10%,12%soybean oil respectively, then added10%,13%,16%water and cultured at (28±1.5)℃for60days. On day0,15,30,45,60, we toke a sample and examine their moisture, crude protein, crude fat, ash, nitrogen free extract, acid value, total number of mold and the content of aflatoxin B1.2. Study of mildew pattern in feed with different fat type:we mixed compound feed, which containing corn, soybean meal and wheat bran as basic ingredient, with12%soybean oil, peanut oil, corn oil and fish oil respectively, then added10%,13%,16%water and cultured at (28±1.5)℃for60days. On day0,15,30,45,60, we toke a sample and examine their moisture, water activity, crude protein, ether extract, ash, nitrogen free extract, acid value, Aflatoxin B1content and the number of molds.3. Effect of fat and its type on qualiy change, mould growth and aflatoxin B1content in corn, soybean meal:This study utilizing corn and soybean meal composed of5%corn oil and soybean oil respectively and18%water cultured (28±1.5)℃for20days to investigate its changeable rule of quality, including moisture, water activity, ether extract, acid value, Aflatoxin B1content and the amounts of molds on the day0,5,10,15and20.Results:1. Our results showed that the moisture, crude protein, ether extract, ash and nitrogen free extract of these treatment groups hardly had any changes(P>0.05) with the extension of incubation time. However, the acid value increased significantly (P<0.05)with the extension of incubation time, we found fat shows a significant effect on acid value of which increased as the fat content rose, otherwise, the amounts of molds significantly increased (P<0.05)with the extension of incubation time in each treatment group when moisture reached up to16%and decreased significantly (P<0.05)when moisture reached to10%,13%, and no AFB1were found during incubation. Therefore, it is moisture rather than fat that actually affect the quality of ration during mildew.2. Our results showed that the moisture, water activity, crude protein, ether extract, ash and nitrogen free extract of these treatment groups hardly had any changes(P>0.05) with the extension of incubation time. However, the acid value increased significantly (P<0.05)with the extension of incubation time. The total number of mold regardless of the type of fat, the moisture content of the ration is to determine the factors for the growth of mold, the amounts of molds significantly increased (P<0.05)with the extension of incubation time in each treatment group when moisture reached up to16%and decreased significantly (P<0.05)when moisture reached to10%,13%, and no AFB1were found during incubation. Therefore, it is moisture rather than fat type that actually affect the quality of feed during mildew.3. Our results showed that there are no significant differences between moisture and water activity in corn or soybean meal when added corn oil or soybean oil accordingly, the moisture and water activity tended to decrease at first, then to increase with the extension of incubation time, ether extract of these treatment groups hardly had any changes(P>0.05) with the extension of incubation time. The acid value increased significantly (P<0.05)with the extension of incubation time, the amounts of molds significantly increased (P<0.05)with the extension of incubation time in each treatment group, The changes of fat composition of corn or soybean meal had no effect(P>0.05) on the total number of molds and AFB1. Therefore, there is no connection between mold growth of corn or soybean meal and their composition of fat type.Conclusion:Fat content showed no significant effect on moisture, crude protein, crude fat, nitrogen-free extract, crude ash and mould growth or AFB1content, except for acid value. Meanwhile, fat type also show no significant effect on moisture, water activity, crude protein, crude fat, nitrogen free extract, crude ash content and mould growth or AFB1content. It is moisture content that mainly influence mould growth. Changes of fat composition from corn or soybean meal neither had an effect on moisture or water activity, nor on mould growth and AFB1generation.