Ambient Temperature and Rainfall: An Effect on Sex Ratio and Litter Size in Deer Mice

1985 ◽  
Vol 66 (2) ◽  
pp. 289-298 ◽  
Author(s):  
P. Myers ◽  
L. L. Master ◽  
R. A. Garrett
Keyword(s):  
Sex Ratio ◽  
Ambient Temperature ◽  
Litter Size ◽  
Deer Mice

scholarly journals Pelage insulation, litter size, and ambient temperature impact maternal energy intake and offspring development during lactation

2010 ◽  
Vol 100 (2) ◽  
pp. 128-134 ◽  
Author(s):  
Matthew J. Paul ◽  
Christiana Tuthill ◽  
Alexander S. Kauffman ◽  
Irving Zucker
Keyword(s):  
Ambient Temperature ◽  
Energy Intake ◽  
Litter Size ◽  
Offspring Development ◽  
Temperature Impact

Maximization of long-term productivity in a rat colony

1972 ◽  
Vol 6 (2) ◽  
pp. 203-206 ◽  
Author(s):  
N. T. Gridgeman ◽  
J. M. Taylor
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Albino Rats ◽  
Mathematical Treatment ◽  
Production Time ◽  
Time Curve ◽  
Intensive Breeding

Maximization of intensive breeding in the animal colony can be approached using a simple mathematical treatment of the production-time curve. It has been found that in a colony of specified-pathogen-free albino rats whose breeding dams were averaging litters of 11 at 6-week intervals, the stock should be entirely replaced at intervals of 27-28 weeks to maximize the output of weanlings. Some data on litter size and sex ratio are also presented.

Twinning and fetal sex ratio in moose: effects of maternal age and mass

1997 ◽  
Vol 75 (11) ◽  
pp. 1945-1948 ◽  
Author(s):  
T. Nygrén ◽  
I. Kojola
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Female Competition ◽  
Offspring Sex Ratio ◽  
Female Age ◽  
Maternal Characteristics ◽  
Low Degree ◽  
Offspring Sex ◽  
Limited Food ◽  
Female Bias

To evaluate hypotheses concerning the effects of maternal characteristics on litter size and offspring sex ratio in a polygynous mammal, we examined how female age and mass affected the number and sex ratio of fetuses in moose (Alces alces). We analysed 420 fetuses collected from 297 females killed in Finland. Females that carried two fetuses were older than females with one fetus, while mass did not affect litter size. Sex ratio was not conclusively linked with maternal quality. The overall lack of difference in the sex ratio (no male bias among fetuses carried by the heaviest females) can be explained by the rather low degree of polygyny and the lack of intense female – female competition for a limited food supply (no female bias among fetuses carried by the heaviest females).

Embryonic resorption, litter size and sex ratio in the grasscutter, Thryonomys swinderianus

2010 ◽  
Vol 118 (2-4) ◽  
pp. 366-371 ◽  
Author(s):  
B.A. Owusu ◽  
E.K. Adu ◽  
E.K. Awotwi ◽  
B. Awumbila
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Thryonomys Swinderianus ◽  
Embryonic Resorption

scholarly journals Effect of transatlantic transport on reproduction of agouti and nonagouti deer mice, Peromyscus maniculatus

1998 ◽  
Vol 32 (1) ◽  
pp. 55-64 ◽  
Author(s):  
V. Hayssen
Keyword(s):  
Litter Size ◽  
Peromyscus Maniculatus ◽  
Deer Mice ◽  
Litter Production ◽  
Transport Stress ◽  
Air Freight ◽  
The Uk ◽  
Size At Birth ◽  
Better Than

In conjunction with establishing colonies of deer mice in the UK, effects of transportation on reproduction in agouti (A) and nonagouti (a) deer mice were assessed. Adults were shipped via ground courier and air freight from Northampton, Massachusetts, USA to Sutton Bonington, Leicestershire, England in February and June. Deer mice were paired upon arrival in Sutton Bonington, whereas matched controls were paired in the original colonies at shipping. To assess reproduction, the following variables were monitored for 110 days for all 96 pairs: number of pairs producing litters, time from pairing to birth, interlitter interval, litter size at birth, and litter size at weaning. Generally, shipping suppressed litter production and delayed its timing, but had less effect on litter size. Overall, 32 of 48 control pairs (67%) produced 69 litters compared with 37 litters from 21 of 48 pairs (44%) after shipping. Pairing-to-first-litter intervals were approximately two oestrous cycles shorter in control animals (39 vs 53 days). Averaged over all litters, litter size was higher in control pairs (4.4 vs 4.0). With respect to genotype, control agouti deer mice were less productive than nonagouti animals, but they reproduced better than nonagoutis after shipping. In control animals, colourmorphs did not differ with respect to litter production or timing, but agouti pairs had smaller litters (first litter: A: 3.1, a: 4.2) and this difference increased at successive litters (third litter A: 3.9, a: 6.0). After shipping, agouti animals produced more litters (A: 22, a: 15), and did so earlier (pairing to birth: A: 47 days, a: 60 days), as well as more frequently (interlitter interval: A: 32 days, a: 51 days). Litter size was also more similar between genotypes after shipping (A: 4.0, a: 4.1). Overall, control agouti animals produced 37% fewer offspring than nonagouti pairs (A: 116 neonates, a: 185 neonates), but after shipping agouti deer mice produced 43% more offspring than nonagouti animals (A: 87 neonates, a: 61 neonates). In sum, transport stress suppressed reproduction for several weeks after shipping and this suppression was exacerbated in nonagouti deer mice.

scholarly journals Effect of season on fertility of sows

2002 ◽  
Vol 56 (1-2) ◽  
pp. 97-104
Author(s):  
Blagoje Stancic ◽  
Mladen Gagrcin ◽  
Stanimir Kovcin
Keyword(s):  
Ambient Temperature ◽  
Litter Size ◽  
Negative Influence ◽  
Economic Problem ◽  
Ovarian Cysts ◽  
Individual Effect ◽  
Summer Period ◽  
Seasonal Factors ◽  
The Individual ◽  
Sexually Mature

Reduced fertility of sows during the warmer period of the year is a well-known occurrence in practical production. Namely, during summer months gilts become sexually mature later, the interval from weaning to estrus is prolonged, there is a greater number of postlactation silent estruses anestrias and ovarian cysts, the value of conception is lower, there are more irregular failed fertilizations, there is a higher degree of embryo mortality, and the litter size is smaller. This is why this occurrence presents an important zootechnological, veterinary-medical and economic problem. Most scientific research shows that this phenomenon is a consequence of the effects of an extended daily photoperiod and a higher ambient temperature. However, the degree of the individual effect of these factors has not been determined clearly, or the physiological and endocrinological mechanisms of their action. It is probably not possible completely to avoid the negative influence of seasonal factors on reduced fertility in sows during the summer period. However, it can be significantly alleviated with a regular maintenance technology, diet, hygiene and medical protection of sows. This paper presents knowledge acquired so far on the manifestation of this phenomenon, its physiological and endocrine bases, as well as possibilities for its practical resolving.

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