雛による成長試験成績の信頼度について

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Day-old White Leghorn chicks were reared for 4 weeks in an electrically heated screen-floor battery with 4 decks. Feed and water were given ad libitum. Body weight and feed intake were measured once a week.1. The data on control groups in 9 experiments carried out last year are summarized in table 2. Each group was composed of 15 male chicks. The variance analysis of weight gains for 4 weeks shown in table 3 indicates that seasonal variation is significant at a 5% level. Standard error of mean weight gain is 13.3g, which is close to 16.5g obtained in Canada3). Standard deviation of individual weight gain is calculated as √1183=34.4g.2. Female chicks were used in a study to check the influence of a lot in the battery as well as of the number of chicks in a group, During the first 2 weeks the groups located on the lowest deck gained in weight significantly less than the other groups did, altough gains for 4 weeks showed little differences among the groups located on different decks, as given in tables 4 and 5. The data clearly indicate that small variation in environmental conditions exert more significant influence on younger chicks than on older ones. Within the range checked, i. e., 12 to 18 birds per group, the number of chicks in a group had no influence on experimental results.3. The amoust of feed spilt for 4 weeks was measured and is given in table 6. When chicks were fed carefully, they spilt 1.2-5.5% of the feed supplied. The spilt feed was recovered by sieving droppings. The sum of all the possible errors, such as errors due to unrecovered spilt feed and errors in measuring feed supplied, is expected to be less than 2%, being usually in the order of 1%. From the data in tables 2 and 4, the rejection limt of feed efficiency of the control diet, composed of corn, soybean meal, rice and wheat brans, and others, was estimated to be 4% on a gain/feed basis or 0.2 on a feed/gain basis.4. Coefficients of variation5) (standard deviation/mean weight gain) at 3 and 4 weeks are the same as shown in table 7. This makes the relative value of the least significant difference costant, i. e. 10%. The rejection limit of feed efficiency at 3 and 4 weeks are also similar. From these data, it can be said that similar conclusians are obtained from the 3-week experiment to 4-week experiment, The experimental error becomes bigger when experimental period was cut shorter than 3 weeks. It is desirable to make experimental period longer than 2 weeks under the present conditions.
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雛による成長試験成績の信頼度について

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