. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 6 BULLKTIX 1121, U. DEPAETxMENT OF A? f^ 7-9 /0-/2,J-3 f-6 7^3 /(HZ, ,h3 f-e 7-9 /t^/^ ,A? 4-6 7-9 X)-/Z, ~7S?^ /9/7 /9/3 /3/9 Fig. 1.—The percentages horn alive, raised of those born aJive, and raised of all young, in the inbred stock during successive 3-month periods, 1916-1919. averages is given in Table 27. The results are presented graphically in Figures 1 to 7. The periods of depression and of good condition are clearly brought out. In a general way there is agreement be- tween the fluctuation of th
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 6 BULLKTIX 1121, U. DEPAETxMENT OF A? f^ 7-9 /0-/2,J-3 f-6 7^3 /(HZ, ,h3 f-e 7-9 /t^/^ ,A? 4-6 7-9 X)-/Z, ~7S?^ /9/7 /9/3 /3/9 Fig. 1.—The percentages horn alive, raised of those born aJive, and raised of all young, in the inbred stock during successive 3-month periods, 1916-1919. averages is given in Table 27. The results are presented graphically in Figures 1 to 7. The periods of depression and of good condition are clearly brought out. In a general way there is agreement be- tween the fluctuation of the percentage born alive, the percentage raised of those born alive, birth weight, rate of gain, and size and frequency of lit- ters. Figure 6, which shows the number of young raised per year by the average mating in each period, per- haps reveals best the changes in environ- mental conditions. The probable absence of relation between sex ratio and season may be seen by comparing Figure 7 with Figure 6. There are various ways in which allowance could be made for these fluctuations. The method which has been adopted is to compare the actual average or index for each experi- ment for the entire period in which it was maintained with the estimated record of the total inbred stock produced simul- taneously. As an ex- ample, we see in Table 22 that there were mature matings in Ex- periment Cl in the pe- riod July-September, 1916. The record of the inbreds as regards frequency of litter dur- ing this period is given in Table 2V as Multiply these together and add the similar products for subsequent periods in the history of Cl. On dividing by the total number of mature matings (3 months' eo s t ^ ^ \ y \ ; ^ J > ^ v'// \ f \ / V*^ w / \ f \ re f/T \ V /^ V ^ f> ^ N / \ s '^1 \ / \ / \ W / \ J \ / \ Pi^ ^ / N ,AJ 4-S 7-9 /(HZ, ,h3 4-ff 7-9 /0-/2„/-J -^^ 7-9 /0S,/y3 4^ 7^9 , TSTe 7¥?7 /&/a T^TW Fig. 2.—The average birth weight of young raised to weaning (33 day
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