REPRODUCTIVE POTENTIAL AND SEX RATIOS OF SNOWSHOE HARES IN NORTHERN ALBERTA

1956 ◽  
Vol 34 (4) ◽  
pp. 273-281 ◽  
Author(s):  
Wm. Rowan ◽  
L. B. Keith
Keyword(s):  
Litter Size ◽  
Sex Ratios ◽  
Reproductive Potential ◽  
Post Mortem ◽  
Comparable Data ◽  
Snowshoe Hares ◽  
Average Litter Size ◽  
Northern Regions ◽  
Two Factors ◽  
Northern Alberta

In conjunction with studies of the "10-year cycle" of snowshoe hares, almost 900 hares were collected in the Anzac district of Alberta during the period May, 1949, to April, 1956. Embryo numbers and sex ratios were among the data gathered from post-mortem examinations of these hares. It was found that the average litter size was 3.82; the modal litter size was four and the range was from one to seven. The average number of litters each season was calculated at 2.75. The annual reproductive potential is thus 10.51 (3.82 × 2.75) young per female hare. This is more than 50% greater than that indicated by comparable data from Minnesota. It is suggested that herein lies the cause of higher peak populations in northern regions. Sex ratios shifted from a marked excess of females in the year 1949–1950 to about even numbers of both sexes during the two subsequent years. Since the change in sex ratio occurred at the peak of the cycle, the two factors are believed to be in some manner correlated.

Effects of ungulate availability on wolf reproductive potential in Alaska

1992 ◽  
Vol 70 (12) ◽  
pp. 2441-2443 ◽  
Author(s):  
R. D. Boertje ◽  
R. O. Stephenson
Keyword(s):  
Litter Size ◽  
Canis Lupus ◽  
Prey Availability ◽  
Subcutaneous Fat ◽  
Reproductive Potential ◽  
Functional Relationships ◽  
Adult Females ◽  
Prey Vulnerability ◽  
Average Litter Size

We compared wolf (Canis lupus) reproductive data for March and April, when ungulate biomass per wolf was high, moderate, and low. The percentage of reproductively active adult females was significantly lower (66% compared with ≥96%, P < 0.001) when ungulate biomass per wolf was low versus moderate or high. Reproductively inactive adult females had significantly less subcutaneous fat (P < 0.01) than reproductively active females when ungulate biomass per wolf was relatively abundant. Average litter size, estimated by counting blastocysts or fetuses, declined significantly (P < 0.001), from 6.9 to 4.6, as ungulate biomass per wolf declined. We conclude that wolf productivity declines as prey availability per wolf declines. However, only when ungulate biomass per wolf declined below levels previously reported in the literature did we observe significant declines in reproductive potential. Ungulate biomass per wolf was low because of large, rapid declines in ungulates and lesser declines in wolves. We recognize that functional relationships, e.g., prey vulnerability and feeding dominance, can influence wolf productivity independently of ungulate biomass per wolf.

SEX RATIOS AND LITTER SIZE IN THE LABORATORY RAT

1958 ◽  
Vol 49 (6) ◽  
pp. 303-304 ◽  
Author(s):  
J. F. KIDWELL ◽  
H. J. WEETH
Keyword(s):  
Litter Size ◽  
Sex Ratios ◽  
Laboratory Rat

Development of a Strain of Rabbits with Congenital Simple Nonsyndromic Coronal Suture Synostosis Part I: Breeding Demographics, Inheritance Pattern, and Craniofacial Anomalies

1994 ◽  
Vol 31 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Mark P. Mooney ◽  
H. Losken Wolfgang ◽  
Michael I. Siegel ◽  
Janice F. Lalikos ◽  
Albert Losken ◽  
...  
Keyword(s):  
Litter Size ◽  
Rabbit Model ◽  
Pedigree Analysis ◽  
Human Populations ◽  
Incomplete Penetrance ◽  
Coronal Suture ◽  
Inheritance Pattern ◽  
Average Litter Size ◽  
Midfacial Hypoplasia ◽  
Congenital Condition

The lack of an animal model of congenital coronal suture (CS) synostosis has prompted the widespread use of an experimental rabbit model using adhesive Immobilization of the CS. Such postnatal models have helped make significant scientific contributions but may still not fully represent all aspects of the human congenital condition. In the March 1993 issue of The Cleft Palate-Craniofacial Journal we reported a female rabbit born in our laboratory with complete bilateral CS synostosis. This follow-up study presents our attempts to breed this animal and establish a strain of cranlosynostotic rabbits. To date, we have accomplished 10 back- and intercrosses with these animals and have produced a total of 71 live offspring; 10 animals exhibited complete nonsyndromic unilateral (plagiocephalic) or bilateral (brachycephalic) CS synostotic deformities at birth, and 19 animals exhibited partial CS synostosis that showed more than 75% growth retardation across the CS (well below the 95% confidence interval for normals). Results revealed that gestational time and litter size averages were consistent with those reported for the strain, although the average litter size decreased with increased inbreeding. By 1.5 weeks of age the completely synostosed animals already exhibited brachycephalic cranial vaults and midfacial hypoplasia compared to unaffected siblings. Initial pedigree analysis suggested an autosomal dominant inheritance pattern with incomplete penetrance and variable expressivity. The development of such a congenital rabbit model may prove useful In helping to understand the etiopathogenesis of this condition In human populations.

A note on ovulation rate and embryonic survival in D'man ewes

1981 ◽  
Vol 32 (2) ◽  
pp. 227-229 ◽  
Author(s):  
A. Lahlou-Kassi ◽  
M. Marie
Keyword(s):  
Litter Size ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Embryonic Survival ◽  
Average Litter Size ◽  
Simultaneous Activity

ABSTRACTThe elements of prolificacy have been analysed for the D'man sheep, a prolific Moroccan breed, by laparotomy on 38 animals. The average ovulation rate was 2·50 (s.e.0·45); a slight difference was observed between nulliparous and multiparous ewes due to high simultaneous activity by both ovaries in the latter group. Embryonic survival (42% overall) was 94% (87 to 100%) for multiparous and 44% (36 to 52%) for the nulliparous ewes at one ovulation, decreasing with increasing numbers of corpora lutea. The average litter size showed an optimum at four ovulations.

Reproduction in the mosaic-tailed rat, Melomys cervinipes (Rodentia :Muridae)

1970 ◽  
Vol 18 (2) ◽  
pp. 171 ◽  
Author(s):  
JM Taylor ◽  
BE Horner
Keyword(s):  
Litter Size ◽  
Reproductive Performance ◽  
Post Partum ◽  
Selective Advantage ◽  
Breeding Period ◽  
Mode Of Reproduction ◽  
Accessory Sex Glands ◽  
Modest Contribution ◽  
Northern Regions ◽  
Autumn And Winter

The mosaic-tailed rat, M. cervinipes, is usually an abundant murid where it occurs in the northern regions of Australia. It is an inhabitant of the forests and their fringe associations and is semi-arboreal. Although the annual reproductive performance is unknown, breeding occurs at least in late spring and summer in more southern areas of its distribution and extends into autumn and winter farther north. Litter size ranges from two to four. The nipple-clinging behaviour of the young appears to be of selective advantage as an escape mechanism. Description of the histology of the gonads and accessory sex glands is given for juveniles, breeding adults, and sexually quiescent adults. M. cervinipes is polyoestrous and a spontaneous ovulator and may experience a post-partum oestrus. Melomys is not known to occur in plague proportions in its native habitat; its mode of reproduction favours a prolonged and modest contribution of young within a breeding period.

scholarly journals Production systems of swine in the rural areas of Rangamati and Khagrachari districts of Bangladesh

2012 ◽  
Vol 40 (1-2) ◽  
pp. 28-33
Author(s):  
ME Hossain ◽  
S Chakma ◽  
MM Khatun ◽  
M Hasanuzzaman ◽  
MY Miah ◽  
...  
Keyword(s):  
Birth Weight ◽  
Litter Size ◽  
Rural Areas ◽  
Economic Condition ◽  
Production Systems ◽  
Economic Benefits ◽  
Disease Prevalence ◽  
Pig Production ◽  
Average Litter Size ◽  
The Mean

The study was undertaken for a period of 60 days to investigate the production systems of swine in Rangamati and Khagrachari districts, Bangladesh. Production systems, particularly housing, feeding, breeding, disease prevalence, vaccination, bio-security, marketing, socio-economic condition and constraints of pig production were investigated during the study period. It was found that the propensity of rearing pig differed significantly (P<0.01) among the pig owners. Pigs were reared mostly by poor and landless peoples (54.7%) followed by marginal (32.1%), medium (9.4%) and large (3.8%). Rearing systems were also different (P<0.01) and the mean figures were 43.4% for free range, 24.5% for tin shed housing , 20.8% for fencing and 11.3% for girth tethering systems. The average litter size, birth weight, post-weaning weight and weaning period were 9.3, 1.72 kg, 9.0 kg and 40.8 days respectively. Prevalence of diseases differed (P<0.01) and most prevalent diseases were diarrhea (35.8%), coccidiosis (20.8%), pneumonia (17.0%) and hemorrhagic septicemia (13.2%). The economic benefits generated from farming were selling of piglets.DOI: http://dx.doi.org/10.3329/bjas.v40i1-2.10787Bang. J. Anim. Sci. 2011. 40 (1-2): 28-33

Reproductive changes in a cyclic population of snowshoe hares

2001 ◽  
Vol 79 (11) ◽  
pp. 2101-2108 ◽  
Author(s):  
Carol I Stefan ◽  
Charles J Krebs
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Litter Size ◽  
Reproductive Output ◽  
Yukon Territory ◽  
The Body ◽  
Decline Phase ◽  
Snowshoe Hares ◽  
Early Increase ◽  
Changes In Pregnancy

Reproductive output was estimated for a cyclic population of snowshoe hares (Lepus americanus) in the Kluane Lake region of the southwest Yukon Territory. Data collected by five researchers were collated over 8 years (1989–1996). Pregnant hares were captured and held in cages until they gave birth so that reproductive characteristics could be measured. Pregnancy rate, litter size, and neonate size fluctuated significantly throughout the cycle, changes occurring about 2 years before corresponding changes in density. Pregnancy rates were nearly 100% early in the breeding season, but declined up to 20% in the last gestation periods of the year. The number of litters produced in a breeding season varied between two (decline phase) and four (low, early increase phase). Litter size varied among years as well as among litters within a year, larger litters being born later in the breeding season. The body mass and size of newborn hares varied by 5–33% among years. The combined changes in pregnancy rate and litter size resulted in a cyclic change in total reproductive output ranging from a low of 6.9 young per female during the decline phase to a maximum of 18.9 during the second year of the low and early increase phases.

scholarly journals Pedigree and Molecular Analyses in the Assessment of Genetic Variability of the Polish Greyhound

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 353
Author(s):  
Małgorzata Goleman ◽  
Ireneusz Balicki ◽  
Anna Radko ◽  
Iwona Rozempolska-Rucińska ◽  
Grzegorz Zięba
Keyword(s):  
Genetic Variability ◽  
Litter Size ◽  
Gene Diversity ◽  
Population Based ◽  
Pedigree Analysis ◽  
Molecular Testing ◽  
Pedigree Data ◽  
Kinship Matrix ◽  
Average Litter Size ◽  
The Mean

The aim of the study was to assess the genetic variability of the Polish Greyhound population based on pedigree analysis and molecular DNA testing and to determine the degree of relatedness among individuals in the population. Pedigree data of 912 Polish Greyhounds recorded in pedigree books since they were opened for this breed were analyzed. For molecular testing, DNA was obtained from cheek swabs taken from 235 dogs of the tested breed. A panel of 21 markers (Short Tandem Repeat—STR) was used. The mean inbreeding determined for the Polish Greyhound population based on pedigree analyses was low and amounted to 11.8%, but as many as 872 individuals of the 912 dogs in the studied population were inbred. A total of 83 founders (at least one unknown parent) were identified, among which 27 founders had both unknown parents. Full-sibling groups consisted of 130 individuals, with a minimum and maximum litter size of 2 and 16, respectively. The average litter size was 5.969. Gene diversity calculated based on the mean kinship matrix was 0.862 and the population mean kinship was 0.138. The founder genome equivalent based on the mean kinship matrix was 3.61; the founder genome surviving level was 12.34; the mean Ne was estimated at 21.76; and the Ne/N ratio was 0.135. The FIS inbreeding coefficient for 21 STR was negative, and the mean FIS value for all loci had a low negative value (−0.018). These values suggest a low level of inbreeding in the examined breed as well as the avoidance of mating related animals.

A FIELD TEST FOR ASSESSING THE WINTER HARDINESS OF ALFALFA IN NORTHWESTERN CANADA

1984 ◽  
Vol 64 (4) ◽  
pp. 917-924 ◽  
Author(s):  
J. S. McKENZIE ◽  
G. E. McLEAN
Keyword(s):  
Field Test ◽  
Winter Hardiness ◽  
Early Winter ◽  
Snow Removal ◽  
Air Temperatures ◽  
Two Factors ◽  
Soil Temperatures ◽  
Natural Snow ◽  
Food Reserves ◽  
Northern Alberta

A procedure is described for separating differences in winter hardiness among alfalfa (Medicago sativa L.) cultivars under field conditions. The procedure depends upon two factors associated with winterkill in northern Alberta during the 1977–1978 winter, namely, low food reserves in the crowns resulting from improper cutting management plus cold stress due to lack of snow in early winter. To induce these conditions we recommend that year-old plants be clipped in mid-June, late July and early September and that snow be removed once from the plot during early winter on the first day that air temperatures below −30 °C are forecasted. Natural snow fall can protect the plot for the remainder of the winter. If soil temperatures do not drop close to the range of the LT50 of the control cultivars, snow cover may be removed again provided air temperatures are below −30 °C. Cultivar rankings for winter hardiness following severe stress induced by snow removal were significantly correlated (r = 0.944**) with the mean survival observed at five locations following natural winter stresses in this region. Although additional work is warranted, the induced stress procedure has real merit in screening winter-hardy genotypes in the field and in assessing management techniques to reduce the effects of stressful winter environments on alfalfa production in northwestern Canada.Key words: Alfalfa, winter hardiness, field test, snow removal, frequent clipping

Population dynamics and life history of the mahogany glider, Petaurus gracilis, and the sugar glider, Petaurus breviceps, in north Queensland

2000 ◽  
Vol 27 (1) ◽  
pp. 21 ◽  
Author(s):  
Stephen M. Jackson
Keyword(s):  
Life History ◽  
Litter Size ◽  
Average Density ◽  
Head Width ◽  
Fragmented Habitat ◽  
Average Litter Size ◽  
Sugar Glider ◽  
History Of ◽  
Petaurus Breviceps ◽  
Natality Rate

Mahogany gliders, Petaurus gracilis, and sugar gliders, Petaurus breviceps, were trapped in an area of open woodland in north Queensland between 1994 and 1996 to examine their population ecology and life history. This study area contained two smaller areas, one consisting of continuous habitat and the other an area of fragmented habitat adjacent to the continuous habitat. Within the continuous area, the mahogany glider had an average density of 0.24 ha–1 whereas the sugar glider had an average density of 0.27 ha–1. In contrast, the density of mahogany gliders in the fragmented habitat averaged only 0.16 ha–1 whereas the density of sugar gliders was higher, at 0.46 ha–1. Both the mahogany glider and the sugar glider showed sexual dimorphism in their weight, head length and head width. The average body weight of both species fluctuated throughout the year with no consistent pattern. The mahogany glider showed a distinct breeding season, with births being recorded between April and October, whereas the sugar glider showed no pattern, with births being recorded during all months except February and April. During the study, all adult females of both species were observed to have bred, with an average litter size of 1.55 and a natality rate of 2.09 for the mahogany glider, and an average litter size of 1.83 and a natality rate of 2.14 for the sugar glider. The sugar glider was able to raise two litters of young within a single year whereas a second litter was raised by the mahogany glider only if the first litter was lost.

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