| We use meat-duck as our experiment object to study the promoting growth effects of selenium and its pathologic changes.One hundred and fifty meat-ducks which are fourteen days old are divided into five groups at random to investigate the promoting growth effects of selenium, and each group has three repeats. The I (1)-IV (1) group are tested groups, and are feeded 0.025 mg / mL (containing pure selenium 0.011 mg / mL), 0.075mg / mL, 0.25 mg / mL, 0.75mg/mL of Na2SeO3 solution respectively. Each meat-duck ingested 1mL per day. The V CD group is control group. Additionally, the same fifty meat-ducks are divided into five groups optionally to observ pathologic changes of selenium. The I (2)~IV(2) group are toxic groups and are feeded 1.0mg/mL, 3.0 mg / mL,5.0 mg / mL.. 10.0mg / mL of Na2SeO3 solution respectively, and the V(2) group is control group and are feeded physiological saline. The results show that:1. The selenium can apparently promote growth of meat-duck. During 28 days of the experiment, we observ and take measure of growth effects of selenium. The results indicate: during the phases of 15-28 days and 29-42 days and 15~42 days, ADG (average daily gain) of I (1) group is respectively increased by 4.4 %, 5.9%, 5.1% as compared to the control group. In the same manner, ADG of II (n is respectively increased by 19.5 % , 10.5 % , 15.2 % and their difference is notable (P < 0.01) . However, the difference of the third group and the control group is not obvious (P > 0.05) and ADG of IV(1) is descended by 11.0 %, 14.4 % and 13.0 % contrasting the control group and the difference between two is notable (P<0.01) .The survival percents of I (1), III(1) IV (1) groups are 100%, the survival percent of II 0.05) . The AFI of II (1) is boosted by 7.9% and the difference of two is very notable (P < 0.01) . The fourth is reduced by 5.1% and their difference is obvious (P < 0.01) . At 29- 42-day-old, the AFI of I()1, III (1) is similar with the control group (P > 0.05) ; the AFI of II(1) is promoted by 4.4%, and P < 0.05; the AFI of IV(1) is reduced by 5.7% and P < 0.05. FCE(Feed Conversion Efficiency): contrasting with the control group, the FCE of I (1) is increase by 5.2% and P < 0.05; the FCE of II(1) is increase by 7.3% and P < 0.01; the difference of FCE between III(1) and control group is inconspicuous; the FCE of IV(1) is reduced by 8.6% and P < 0.01.2. The pathological changes of selenium are: the symptom of poisoning is exacerbated along with the increase of selenium intake. The I(2), II(2), III(2) group of ducks appear the symptom of poisoning after the selenium intake a day. And IV <2>group are indicative of obvious symptom of poisoning after the selenium intake an hour and die in nine days. When the experiment is finished, the death rate of I(2), II(2), III(2), IV(2) are respectively 0, 20%, 50%, 100%. The major criteria are: the ducks of IV(2) group appear shortnessofbreath, locomotor ataxia, head tumefaction, parting from flock, shutting eyes, abandon of appetite, brick red fluid from mouth or nose, and excreting green or white loose stool; the II (2), III (2) group of ducks all appear psyche depressed, inappetence, respiratory difficulty, macilency, and excreting green or white loose stool; the symptom of poisoning of I (2) is mild than others, such as lowgrade tumefaction of head and moisst of conjunctiva, which is temporary, inappetence, decline of capability of growing. And dissected changes are: the IV(2) group's liver is tumefied and gangrened along with...
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