Effects Of Irradiation Sterilization On Feeds In Specific Pathogen-Free Laboratory Animals

The irradiation has been generally adopted to sterilization feed for specific pathogen-free (SPF) animals overseas since 1970s.The advantage of irradiating-sterilization is that no thermo-exchange happened in the process.In China, the feed is usually sterilized by autoclave,which resulted considerable loss of main nutrition compositions and vitamins. In foreign countries, Co⁶⁰ was adopted to sterilze the feed at a dose of 25kGy.Hower, there were still no standard dose of Co⁶⁰ sterilizing feed in SPF pigs at present in China.In present study, we sterilized feed for SPF pigs in different dose of Co⁶⁰,and the quality guarantee period of the feed sterilized was determined. The results are as followed:Experimentâ… : The feed for SPF pigs had been divided into five different groups,which were irridated by Co⁶⁰ at dose of 5,10,15,20 and 25kGy respectively.In contrast, another feed was not irradiated. Microbiological examination and the measurement of the major nutritious components and vitamins were carried on in 0,7,14,21 and 28 days after irradiation. The feed at dose of 15 kGy kept sterile for 30 dys at room temperature. Mositure,CP, VB₂, Vpp and VA of feed had very significant difference between different irradiation treatments(P＜0.01), but EE, Ash,VB₁, VB₆, VE of feed had no significant difference(P＞0.05).The result of this experiment indicated that the optimal dose for feed of SPF experimental miniature pigs was 15 kGy.Experimentâ…¡: The powder feed for SPF pigs had been divided into four different groups, two groups were made into pellets. One kind of powders and one kind of pellets were heatd at 70℃for 2 hours, others are heated for 4 hours. Four kinds of feed were all irridated by at dose of 0,3,6,9, 12kGy respectively. Microbiological examination and the measurement of the major nutritious components were carried on in 0,7,14,21 and 28 days after irradiation. The two kinds of feed heated 2 hours at dose of 9 kGy kept sterile for 30 dys at room temperature, others heated 4 hours at dose of 6 kGy kept sterile. All major nutritious components of all kinds of feed had no significant difference(P＞0.05). The powder and pellets had no effect on irradiating-sterilization dose.The following conclutions can be drawn from all the above results:1. Irradiating-sterilization dose had contacts with counts of microbes at first. When counts of microbes were 10⁶cfu/g, 10⁴cfu/g, 10²cfu/g, irradiating-sterilization dose were 15kGy, 9kGy and 6 kGy respectively and kept sterile for 30 dys at room temperature.2. Type of feed had no effect on irradiating-sterilization dose, Irradiating-sterilization dose can decrease by optimal treatment before irradiation.