scholarly journals The fertility of mice selected for large or small body size

1960 ◽  
Vol 1 (3) ◽  
pp. 393-407 ◽  
Author(s):  
Ruth E. Fowler ◽  
R. G. Edwards
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Small Body ◽  
Follicle Stimulating Hormone ◽  
Weight Ratio ◽  
Total Body Weight ◽  
Control Line ◽  
Small Body Size ◽  
Natural Mating ◽  
Stimulating Hormone

The fertility of two unrelated strains of mice (strains N and C) which had both been selected for large and small body size has been studied.The fertility of pairs of mice in the large or small lines of strain C was unimpaired by selection. In strain N, some of the pairs in the large and small lines, but not in the control line, were sterile. Sterility in the large line was due to the low libido of the males, and not to female infertility. Sterility in the small line was probably due to hypo-functioning of the anterior pituitary of some females: the oestrous cycle was delayed or absent, some mice failed to ovulate after mating, and a high proportion of those mating had no implanted embryos at 12 days' gestation. Oestrus and ovulation could be induced in mice of the small line of strain N by exogenous gonadotrophins, and the proportion of mice with implanted embryos was considerably increased by progesterone supplements.The number of eggs found after natural mating was considerably higher in large mice than in small mice, and was significantly correlated with body weight in the small line of strain C only. The egg-number/body-weight ratio was higher in the lines of strain C than in those of strain N, though the ratios were similar when carcass fat was subtracted from total body weight.The amount of endogenous follicle-stimulating hormone secreted by the mice of the five lines was estimated by inducing ovulation with various amounts of exogenous gonadotrophins, and comparing the number of eggs found after each dose with the mean number ovulated after natural mating. Estimates of the amount of follicle-stimulating hormone secreted by mice of strain C were higher than those for mice of strain N.Differences in the rates of growth and in the numbers of eggs ovulated after natural mating indicate a higher level of pituitary activity in strain C than in strain N.

scholarly journals The efficiency of food utilization, digestibility of foodstuffs and energy expenditure of mice selected for large or small body size

1962 ◽  
Vol 3 (1) ◽  
pp. 51-68 ◽  
Author(s):  
Ruth E. Fowler
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Energy Expenditure ◽  
Small Body ◽  
Energetic Efficiency ◽  
Food Utilization ◽  
Control Line ◽  
Small Body Size ◽  
Gross Efficiency ◽  
Body Activity

The efficiency of food utilization, the digestibility of foodstuffs, energy metabolism, and body activity have been studied in three lines of mice, one selected for large, another for small body size, and a third, control, line.The gross efficiency of food utilization was highest in the large line, intermediate in the control line and lowest in the small line between 21 and approximately 35 days of age. During this period, gross efficiency declined in the large and control lines with increasing size and decreasing growth-rate, presumably due to an increase in maintenance costs in comparison with the weight gained. In the small line, the efficiency of food utilization increased up to 35 days of age but declined thereafter. The energetic efficiency (measured in Calories) was higher in the large than in the small line up to 4 weeks of age, i.e. when the growth-rate was high, and after 6 weeks of age, when fat was being deposited at an increased rate.The increased efficiency of large mice was not entirely associated with a greater proportion of the ingested food being absorbed from the gut. Large mice absorbed a greater proportion of protein, though the difference was not sufficient to account for the large weight difference between the large and small lines.The energy expenditure of mice of the large line was greater than that of the small line at all ages and similar for the same body weights. The reduced growth-rate of small mice was not due to abnormally high or low energy costs. There was no evidence that body activity determined or restricted the rate of growth in either line.Mice selected for small size were phenotypically unlike pituitary dwarf mice, although the low nitrogen retention during the growing-period indicated a deficiency of some growth stimulus.

The growth and carcass composition of strains of mice selected for large and small body size

1958 ◽  
Vol 51 (2) ◽  
pp. 137-148 ◽  
Author(s):  
Ruth E. Fowler
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Small Body ◽  
Carcass Composition ◽  
Small Body Size ◽  
Body Protein ◽  
Percentage Composition ◽  
Growing Period ◽  
Constant Rate ◽  
Rates Of Growth

The growth and carcass composition of two strains of mice (N- and C-strain), which had both been selected for large and small body size by Falconer, have been studied.Differences in body weight between mice of the N-strain and their controls were apparent at birth and were fully maintained up to 30 weeks of age. The patterns of growth were similar in all three lines, although the large line grew at a faster rate than the small line, the controls being intermediate. Differences in absolute and relative rates of growth between the three lines reach a maximum from 21 to 35 days of age and declined thereafter.Growth in the large line of the N-strain from 14 to 40 days of age was largely due to an increase in body protein and water; after this age, increase in weight was caused mainly by fat deposition. In the small line of this strain, protein, water and fat were deposited at a more constant rate during the whole growing period. Differences in rates of growth may account for the differences in the percentage composition found between mice of the large and small lines of the N-strain at the same age.

scholarly journals The effect of replicated selection for body weight in mice on vertebral shape

1988 ◽  
Vol 51 (2) ◽  
pp. 129-135 ◽  
Author(s):  
D. R. Johnson ◽  
P. O'Higgins ◽  
T. J. McAndrew
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Fourier Analysis ◽  
Shape Change ◽  
Small Body ◽  
Small Body Size ◽  
Selection For ◽  
Main Component ◽  
Vertebral Shape ◽  
And Control

SummaryThe shapes of T1 and T2 vertebrae from unselected Q strain mice and from strains selected for large and small body size were studied by Fourier analysis in order to ascertain whether shape change was produced by size selection. The vertebrae of large, small and control strains were easily distinguishable, but between replicate groups shape differences were less marked. The main component of shape change was size related, but mice unselected for size also showed a non-size-related shape change.

scholarly journals Adaptive significance of small body size under poor socio-economic conditions in southern Peru

1973 ◽  
Vol 39 (2) ◽  
pp. 255-261 ◽  
Author(s):  
A. Roberto Frisancho ◽  
Jorge Sanchez ◽  
Danilo Pallardel ◽  
Lizandro Yanez
Keyword(s):  
Body Size ◽  
Small Body ◽  
Adaptive Significance ◽  
Economic Conditions ◽  
Small Body Size ◽  
Southern Peru

Decline of Cane Toad, Bufo-Marinus, Populations - Status of Urban Toads

1986 ◽  
Vol 13 (4) ◽  
pp. 597 ◽  
Author(s):  
WJ Freeland ◽  
BLJ Delvinquier ◽  
B Bonnin
Keyword(s):  
Body Size ◽  
Urban Population ◽  
Small Body ◽  
Rural Populations ◽  
Small Body Size ◽  
High Food ◽  
Cane Toad ◽  
Water Shortages ◽  
Toad Bufo ◽  
Low Rate

Cane toads from an urban population in Townsville, Qld, exhibit poor body condition and small body size, as do toads in populations around Townsville which have declined in numbers. The small body size and poor condition are associated with a high food intake and a low rate of parasitism. The results suggest that decline of rural populations is not a product of parasitism, or food and or water shortages related to unusually adverse seasonal conditions. Populations of cane toads around Townsville declined more than 3 years before this study.

scholarly journals Costs for health care of Holstein cows selected for large versus small body size

2012 ◽  
Vol 95 (9) ◽  
pp. 5384-5392 ◽  
Author(s):  
J.C. Becker ◽  
B.J. Heins ◽  
L.B. Hansen
Keyword(s):  
Health Care ◽  
Body Size ◽  
Small Body ◽  
Holstein Cows ◽  
Small Body Size

Completeness of the fossil record: Estimating losses due to small body size

Geology ◽  
2006 ◽  
Vol 34 (4) ◽  
pp. 241 ◽  
Author(s):  
Roger A. Cooper ◽  
Phillip A. Maxwell ◽  
James S. Crampton ◽  
Alan G. Beu ◽  
Craig M. Jones ◽  
...  
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Small Body ◽  
Small Body Size
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