Microtus population biology: dispersal in fluctuating populations of M. townsendii

1976 ◽  
Vol 54 (1) ◽  
pp. 79-95 ◽  
Author(s):  
Charles J. Krebs ◽  
Irene Wingate ◽  
Janice LeDuc ◽  
James A. Redfield ◽  
Mary Taitt ◽  
...  
Keyword(s):  
Body Weight ◽  
Small Mammals ◽  
Population Biology ◽  
Sexual Maturity ◽  
Population Regulation ◽  
Leucine Aminopeptidase ◽  
Microtus Pennsylvanicus ◽  
Breeding Density ◽  
Declining Populations ◽  
Fluctuating Populations

If spacing behavior limits the breeding density of small mammals, the colonization of vacant areas by surplus animals ought to show how and when population regulation is achieved. Two 0.8-ha areas near Vancouver, British Columbia, were cleared of voles from May 1971 to December 1973 and the colonization of the cleared areas was monitored every 2nd week. All colonists were removed. The colonization rate of the experimental areas was most rapid when populations were increasing rapidly in the adjacent control areas, and much of the loss of individuals in increasing control populations was due to dispersal rather than death. In declining populations very little dispersal occurred. Voles of high body weight (> 60 g) were characteristic of late increase and peak populations, but few of these heavy voles dispersed to the vacant experimental areas. Weight at sexual maturity was lower in colonizing voles, particularly among females. About 25% more males than females dispersed into the vacant areas. Colonizing voles were not a genetically random subsample from the control populations. Some leucine aminopeptidase (EC 3.4.11.1) genotypes were more prone to dispersal, particularly when populations were increasing. These results are in agreement with the results of earlier experiments on Microtus pennsylvanicus and M. ochrogaster, and they point to the need for more detailed studies of the dispersal process in voles.

Ventilation standards for small mammals

1964 ◽  
Vol 19 (2) ◽  
pp. 360-362 ◽  
Author(s):  
Leonard I. Kleinman ◽  
Edward P. Radford
Keyword(s):  
Body Weight ◽  
Tidal Volume ◽  
Small Mammals ◽  
Artificial Respiration ◽  
Alveolar Ventilation ◽  
Breathing Frequency ◽  
Slide Rule ◽  
Physiological Dead Space ◽  
The Relationship ◽  
Tidal Volume Breathing

Ventilation standards for small mammals have been prepared on the basis of the relationship between alveolar ventilation and metabolism. On the assumptions of an average respiratory quotient of 0.85 and physiological dead space directly proportional to tidal volume, the relationship between tidal volume, breathing frequency, and body weight has been derived. The standards are presented in a graphic form and as a slide rule. animal ventilation; artificial respiration; tidal volume, breathing frequency and body weight relationship Submitted on August 15, 1963

scholarly journals DOMINANCE AND EPISTASIS IN HETEROSIS OF WHITE LEGHORN STRAIN CROSSES

1987 ◽  
Vol 67 (3) ◽  
pp. 663-680 ◽  
Author(s):  
R. W. FAIRFULL ◽  
R. S. GOWE ◽  
J. NAGAI
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Significant Contribution ◽  
Production Traits ◽  
White Leghorn ◽  
Cross Combination ◽  
Commercial Strain ◽  
Better Than

Four unrelated pure strains of White Leghorns including a grandparent strain from industry and 12 two-strain, 24 three-strain, 24 four-strain and 12 F2 strain crosses produced contemporaneously were used to examine the role of dominance and epistasis in heterosis. A control strain and a commercial strain were also included. For egg weight, the heterosis observed closely approximated that expected due to dominance alone. For sexual maturity and body weight, dominance was the major component of heterosis, but epistasis made a significant contribution — additive by additive (A × A) genetic effects for sexual maturity and 140-d body weight, and parental epistasis for mature body weight. Both dominance and epistasis played a significant role in heterosis for egg production traits. A × A, dominance by dominance (D × D) and additive by dominance (A × D) epistasis were all important for hen-housed egg production and hen-housed egg yield. For hen-day rate of egg production, A × A epistasis was significant only early in the laying year (to 273 d), A × D and D × D were significant to 385 d and in the full year (to 497 d); however, none (A × A, A × D and D × D) was significant near the end of lay (386–497 d). Overall heterosis estimates for full year egg production measured as hen-housed egg production to 497 d or hen-day rate from housing to 497 d clearly showed that on average two-strain crosses were superior to three-strain crosses which were superior to four-strain crosses which in turn exceeded the F2 crosses. Nevertheless, several three-strain crosses had performance for egg production that was equal to or better than the two-strain cross with the highest egg production. Thus, in commerce, where the level of egg production is of great economic importance, the testing and use of a specific three-way cross combination will usually result in a better commercial product. Key words: Heterosis, egg production genetics, epistasis, stocking rate, strain cross, White Leghorn

scholarly journals Occurrence and practical solvent possibility of gilts preinsemination anestrus

2010 ◽  
Vol 26 (1-2) ◽  
pp. 37-46 ◽  
Author(s):  
I. Stancic ◽  
M. Gagrcin ◽  
M. Jovicin ◽  
S. Jovanovic
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Good Health ◽  
Reproductive Efficiency ◽  
Ovarian Activity ◽  
Genetic Traits ◽  
Paper Review

Gilts reproductive efficiency is one of the primary factors of successful piglets' production. This performance, among other things, is expresses by the number of pregnant gilts, with desirable genetic traits, body weight and age, sexual maturity status, and general good health, provided for the replacement of sows in primary herd. This goal is very difficult to achieve in practical conditions. The main reason is occurrence of prolonged preinsemination anoestrus (oestrus was not detected even after 8 months of age). This paper review the occurrence of prolonged preinsemination anoestrus, based on the results of our and study of other authors. All studies consistently show that, in most of these gilts, pubertal cyclic ovarian activity were established, that silent oestrus occurred in only 4% of the cyclic gilts, and that this problem can be solved by applying appropriate technologies for oestrus detection, and by treatment with adequate hormonal preparations.

scholarly journals Seasonal variations in the population biology of Salmostoma bacaila (Cyprinidae) from a tributary of the Payra River, Bangladesh

2019 ◽  
pp. 113-119
Author(s):  
Ahamed Ahamed ◽  
Faruque Ahmed Zoarder ◽  
Jun Ohtomi
Keyword(s):  
Sex Ratio ◽  
Seasonal Variations ◽  
Population Biology ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Spawning Season ◽  
Frequency Distributions ◽  
Size At Sexual Maturity ◽  
Management And Conservation

Some biological parameters of Salmostoma bacaila – including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor – were studied. Samples were collected seasonally during June 2017 to May 2018 from a tributary of the Payra River. The overall sex ratio was significantly different from the expected value of 1:1 (p < 0.001), in favour of male specimens. Females were significantly larger than males. Size at sexual maturity was estimated at 7.6~7.7 cm total length. Seasonal variations in the gonadosomatic index (GSI) indicate that the main spawning season is from spring to summer. The LWRs showed negative allometric growth in both sexes, but with clear seasonal variation. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The fin¬dings of this study will be helpful for management and conservation of S. bacaila populations.

scholarly journals Effect of Immediately-After-Birth Weaning on the Development of Goat Kids Born to Small Ruminant Lentivirus-Positive Dams

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 822 ◽  
Author(s):  
Nalbert ◽  
Czopowicz ◽  
Szaluś-Jordanow ◽  
Moroz ◽  
Mickiewicz ◽  
...  
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Linear Models ◽  
Small Ruminant ◽  
Negative Impact ◽  
Body Weight Gain ◽  
Mixed Linear Models ◽  
Daily Body Weight ◽  
The Mean ◽  
The Difference

A longitudinal study was carried out to investigate the influence of two different rearing systems of young kids on their development to sexual maturity. Kids born to small ruminant lentiviruses-infected (SRLV) female goats were split into two groups: the immediately-after-birth weaned group and the unweaned group. Kids’ body weight (BWT) was measured before the first consumption of colostrum, and then at the age of one week, and one, two, four, and seven months. The relationship between the rearing system and BWT at each age was investigated using mixed linear models adjusted for potential confounders. The mean BWT of kids of the immediately-after-birth weaned group was significantly lower at the age of one week, one month, and two months, and then the difference became insignificant. The mean daily body weight gain (DWG) was significantly lower in the immediately-after-birth weaned group during the whole first month of life, but then DWG in both groups became equal. Crude mortality rate did not differ significantly between groups. This study shows that weaning kids immediately after birth does not appear to have any negative impact on kids’ development except transient growth retardation, which is fully compensated until they reach sexual maturity.

The Small Mammals of Little Nourlangie Rock, NT. V. The Effects of Fire

1981 ◽  
Vol 8 (3) ◽  
pp. 515 ◽  
Author(s):  
RJ Begg ◽  
KC Martin ◽  
NF Price
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Small Mammals ◽  
Pregnant Females ◽  
Preferred Habitat ◽  
Closed Forest ◽  
The Mean ◽  
Fuel Characteristics ◽  
Release Program

Following a capture-mark-release program (February 1977-June 1979) on Dasyurus hallucatus, Antechinus bilarni, Zyzomys argurus and Zyzomys woodwardi, the study area was burnt to determine the effects of fire on these species. The area was described in terms of fuel characteristics and details of the fire were recorded. Post-fire trapping began July 1979 and continued until July 1980 (15,600 trap-nights). A. bilarni was the only species to suffer an increased mortality immediately after the fire, but the number of animals known to be alive declined over the year following the fire, for all species except D. hallucatus. The fire affected reproduction in all four species, but in different ways. Breeding in D. hallucatus was delayed by 1 month, and the mean number of young leaving the pouch per female was lower than before the fire. A higher number of resident females kept recruitment up. Litter size in A. bilarni was not affected, but a reduced number of resident females meant that recruitment was halved. Zyzomys argurus and Z. woodwardi showed few lactating and pregnant females in July-August following the fire, and the numbers of juveniles were lower than in the previous two years. Following the fire, no detectable differences in body weight were recorded, but all species except D. hallucatus changed their preferred habitat, moving to the Scree Slope. Z. woodwardi was most affected, and moved from the Closed Forest.

Surplus yearlings and the regulation of breeding density in blue grouse

1980 ◽  
Vol 58 (5) ◽  
pp. 896-905 ◽  
Author(s):  
Fred C. Zwickel
Keyword(s):  
Body Weight ◽  
Control Area ◽  
Removal Experiment ◽  
Breeding Density ◽  
Surrounding Area ◽  
Total Removal ◽  
Breeding Range ◽  
Experimental Area ◽  
Large Numbers ◽  
Dendragapus Obscurus

An experiment in which yearlings of both sexes of blue grouse (Dendragapus obscurus fuliginosus) were removed from breeding range showed that about two times, or more, yearlings of each sex were identified here as compared with a nearby control area, though numbers of "surplus" yearlings varied among years. The removal of large numbers of yearlings from the experimental area did not reduce breeding density, except ephemerally in 1 year. Nor did the removal of these birds affect populations in the surrounding area. These data confirm results from earlier studies with blue grouse, that surplus yearlings of both sexes are present on the breeding range. Replacement yearlings of both sexes (those taking the place of birds removed) were able to breed, but those removed sequentially (1974 to 1976) were lighter in body weight than those captured on control areas or those that settled synchronously after a near-total removal experiment in the same area. I infer from these results that some form of behaviour keeps surplus yearlings from settling on the breeding range and that this behaviour is a key mechanism involved in the regulation of breeding density. The important behaviour may involve either yearling–yearling or adult–yearling interactions.

The effect of feed restriction on sexual maturity and initial reproductive performance of broiler pullets under different light treatments

1969 ◽  
Vol 9 (39) ◽  
pp. 417 ◽  
Author(s):  
RAE Pym ◽  
R Sledge
Keyword(s):  
Body Weight ◽  
Reproductive Performance ◽  
Sexual Maturity ◽  
Feed Restriction ◽  
Restricted Feeding ◽  
Egg Weight ◽  
Laying Performance ◽  
The Mean ◽  
The Difference ◽  
Lighting Systems

An experiment was conducted to examine the effect of restricted feeding under two lighting systems during the rearing period on the initial laying performance of broiler type pullets. The rearing treatments were imposed at nine weeks of age, removed at 22 weeks and the trial was discontinued at 36 weeks of age. The feeding treatments (restricted versus ad lib.) were arranged factorially with the lighting treatments (decreasing versus increasing). Birds reared on restricted feeding reached sexual maturity 16 days later than full fed birds, ate 17 per cent less feed to 22 weeks and gained seven per cent less in body weight to 24 weeks of age and ten per cent less to 36 weeks. Birds reared under the decreasing lighting regime reached sexual maturity at the same age as those reared under increasing lighting, ate five per cent more feed during the rearing and laying periods and gained five per cent more in body weight to 24 weeks. The mean weight of eggs laid between 24 and 34 weeks of age from pullets subjected concurrently to decreasing lighting and restricted feeding was approximately two grams heavier than that of the other three treatment combinations. Mean egg weight was one gram greater in the restricted than in the full fed group, although the difference was not statistically significant. Laying mortality was lower in the restricted fed group than in the full fed group.

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