A comparison of reproduction in two chipmunk species (Eutamias)

1969 ◽  
Vol 47 (4) ◽  
pp. 603-608 ◽  
Author(s):  
David H. Sheppard
Keyword(s):  
Comparative Study ◽  
Breeding Season ◽  
Litter Size ◽  
Reproductive Potential

Eutamias amoenus and E. minimus are potential competitors in western Alberta. The former species has larger litters and reproduces at an earlier age, on an average, than the latter. Other aspects of reproduction (breeding season, prenatal mortality) do not appear to differ greatly, though supporting data are somewhat inadequate. The higher reproductive potential should confer an advantage on amoenus in competition with minimus. The observed difference in litter size of these two congeners seems to be best explained by a difference in available food in the two habitats. This hypothesis should be tested by a comparative study of the energetics of the two species populations.

Performance of lambs from three crossbred ewe types

1984 ◽  
Vol 39 (1) ◽  
pp. 81-87 ◽  
Author(s):  
N. D. Cameron ◽  
C. Smith ◽  
F. K. Deeble
Keyword(s):  
Comparative Study ◽  
Litter Size ◽  
Survival Rates ◽  
England And Wales ◽  
Second Stage

ABSTRACTThe performance of predominantly Suffolk-sired lambs from Border Leicester (BL), Bluefaced Leicester (BFL) and ABRO Damline (DL) crossbred ewes was compared on 18 commercial and college farms throughout England and Wales. The comparison took place over the 5-year period 1977 to 1981 and was the second stage in a comparative study on the productivity of the crossbred ewes. A total of 1277 crossbred ewes were involved with data on up to 3 years lambings per ewe, giving a total of 3522 mating records and 4864 lamb records.The BFL lambs were heaviest and the DL lambs were lightest. The DL lambs had the lowest survival rates, and the BFL lambs the highest. The BFL lambs were slaughtered earlier (12 days) and at heavier weights (1·4 kg) than the DL and BL lambs, and had slightly heavier carcasses. The DL and BFL carcasses had better MLC carcass classifications than the BL, resulting in an advantage of 4 p/kg of carcass.In productivity per ewe, the BFL litters had the highest slaughter and carcass weights and the highest income per litter, with the DL litters intermediate. An attempt was made to express productivity per unit of sheep weight maintained, taking account of ewe weight, litter size and the lamb slaughter date. On this index, the DL were marginally superior to the BFL, and both were superior to the BL.

A comparative study of fat and protein levels in the colostrum of prolific and non-prolific sheep

1998 ◽  
Vol 1998 ◽  
pp. 104-104
Author(s):  
J.M.L. Anderson ◽  
M.N.I. Barclay ◽  
M. J. Harvey ◽  
A. Waterhouse
Keyword(s):  
Body Weight ◽  
Comparative Study ◽  
Litter Size ◽  
Protein Levels

It is vital that lambs receive at least 50ml/kg body weight of colostrum as soon as possible after birth. Without this, the lamb will be deprived quickly of energy for thermoregulation, as well as antibody protection. Colostrum contains high levels of fats and lactose, proteins and vitamins; however the consistency and colour vary between individual animals. Little is known of the cause of these variations. This experiment aimed to examine whether there were breed, age, genotype and litter size differences in the fat and protein levels of ewe colostrum collected within one hour of parturition.

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.

The effect of melatonin treatment during the seasonal anoestrus on the superovulatory response and embryo production of high-prolificacy Rasa Aragonesa ewes before culling

2003 ◽  
Vol 2003 ◽  
pp. 82-82
Author(s):  
F. Forcada ◽  
J.A. Abecia ◽  
J.A. Valares
Keyword(s):  
Embryonic Development ◽  
Breeding Season ◽  
Litter Size ◽  
Direct Effect ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Melatonin Treatment ◽  
Embryo Production ◽  
Spring Equinox

The efficacy of melatonin implants inserted around the spring equinox to improve fertility and ovulation rate or litter size in Mediterranean ewes has been previously reported (Chemineau et al., 1996; Forcada et al., 2002a.), indicating the ability of the hormone to regulate the hypothalamic activity (Viguié et al., 1995). Moreover, a direct effect of melatonin on corpora lutea and embryonic development has been also reported (Wallace et al., 1988; Abecia et al., 2002). The use of prolific Rasa Aragonesa (RA) ewes (a Mediterranean breed) before culling as embryo donors has been previously tested in the breeding season (Forcada et al., 2002b.). The aim of this experiment was to improve embryo production during the seasonal anoestrus period in selected superovulated RA ewes at the end of their reproductive lives through the use of melatonin.

scholarly journals A comparative study of litter size and sex composition in a large dataset of callitrichine monkeys

2019 ◽  
Vol 81 (9) ◽  
Author(s):  
Dakota E. McCoy ◽  
Brett M. Frye ◽  
Jennifer Kotler ◽  
Judith M. Burkart ◽  
Monika Burns ◽  
...  
Keyword(s):  
Comparative Study ◽  
Litter Size ◽  
Sex Composition ◽  
Large Dataset ◽  
Size And Sex Composition

Diet and breeding of the rufous spiny bandicoot Echymipera rufescens australis, Iron Range, Cape York Peninsula

2007 ◽  
Vol 29 (2) ◽  
pp. 169 ◽  
Author(s):  
D.I. Shevill ◽  
C.N. Johnson
Keyword(s):  
Breeding Season ◽  
Litter Size ◽  
Reproductive Rate ◽  
High Fecundity ◽  
Iron Range ◽  
Seed Disperser ◽  
Faecal Analysis ◽  
Live Trapping ◽  
Cape York ◽  
Trapping Grid

A population of the rufous spiny bandicoot Echymipera rufescens australis was studied for 14 months by live-trapping, and diets were determined by faecal analysis. The population had a high density (approximately 48 individuals on a trapping grid of 2.25 ha). A wide variety of foods were eaten, but fruits and seeds contributed the largest proportion of material to faeces, followed by invertebrates, fungi and dicot plants. Echymipera rufescens may potentially be a significant seed disperser for some plants, such as Pandanus zea. There was a short breeding season, with births occurring between December and March. Females produced one or two litters per year. Mean litter size was just under three, and litter size increased with the mother?s mass. Females produced a mean of 4.9 young per year. We conclude that although E. rufescens is a ?typical? bandicoot in that it is omnivorous and has high fecundity, it is more frugivorous and has a somewhat lower reproductive rate than other Australian bandicoots.

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.

A comparative Study of Regularized Regression Approaches using R: Application to SNP and Litter Size of Yorkshire Pigs

2014 ◽  
Vol 48 (3) ◽  
pp. 147-155
Author(s):  
Minsu Park ◽  
◽  
Tae-Hun Kim ◽  
Eun-Seok Cho ◽  
Heebal Kim ◽  
...  
Keyword(s):  
Comparative Study ◽  
Litter Size ◽  
Regularized Regression ◽  
Yorkshire Pigs

The effect of melatonin implants on breeding activity and litter size in commercial sheep flocks in the UK

1990 ◽  
Vol 50 (1) ◽  
pp. 111-121 ◽  
Author(s):  
W. Haresign ◽  
A. R. Peters ◽  
L. D. Staples
Keyword(s):  
Breeding Season ◽  
Litter Size ◽  
Statistical Significance ◽  
Mating Period ◽  
The United Kingdom ◽  
Commercial Farming ◽  
Natural Breeding ◽  
The Individual ◽  
The Uk ◽  
Subcutaneous Implant

ABSTRACTTwo trials were undertaken to investigate the effects of treating seasonally anoestrous ewes with melatonin implants on date of first oestrus and other aspects of reproductive performance.Trial 1 involved a total of 368 Mule ewes and 79 Scottish Blackface ewes on five farms, approximately half of which were treated with a single subcutaneous implant of melatonin (Regulin®), containing 18 mg melatonin, between 23 July and 6 August 1986 and the remainder acted as untreated controls. Treatment had no significant effect on the date of first oestrus or conception rate in Mule ewes, although it increased the number of Scottish Blackface ewes mating (92% v. 73%) and the number of mated ewes conceiving (69% v. 54%) in a 5-week mating period, resulting in significantly more treated ewes lambing (63% v. 37%; P < 0·01). Litter size was higher in 4/5 flocks, although this only reached statistical significance in one Mule flock and the Scottish Blackface flock.A total of 2116 ewes from 17 commercial flocks were used in trial 2, approximately half of which were Suffolk/Suffolk-cross ewes and the remainder Mule/Mule-cross ewes. Implantation with melatonin occurred between 22 June and 24 July 1987. Flocks with over 100 ewes were divided into three equal-sized groups and treated with either 18 mg melatonin (one implant of Regulin, 36 mg melatonin (two implants of Regulin given at the same time) or acted as untreated controls. Flocks with less than 100 ewes contained only the 18 mg melatonin and untreated control groups. Treatment with melatonin significantly advanced the date of first oestrus in most flocks of both breeds (P < 0·05) but the magnitude of this effect was variable. Significant (P < 0·05 at least) increases in ‘potential’ (from scanning) mean litter size (+0·13 to +0·18) and actual mean litter size (+0·11 to +0·14) resulting from treatment with melatonin were apparent in ewes of both breeds when the data were pooled across all flocks, but only in 4/17 of the individual flocks.These results indicate that treatment with melatonin implants may be a simple and effective way of advancing the breeding season and enhancing litter size of early lambing flocks under commercial farming conditions in the United Kingdom, but treatment must be given >60 days before the start of the natural breeding season for benefits in date of first oestrus to be manifest.

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.

Sign in / Sign up

Export Citation Format

Share Document