In certain production environments, beef cows are mated during a breeding season that starts in early summer. Cows found not to be pregnant at the end of the breeding season could either be culled or retained and remated the following summer. Alternatively, nonpregnant cows could be mated in the winter. This option would result in having both a spring and a fall calving herd. The purpose of our...

Stress and reproduction are generally thought to work in opposition to one another. This is often manifested as reciprocal relationships between glucocorticoid stress hormones and sex steroid hormones. However, seasonal differences in how animals respond to stressors have been described in extreme environments. We tested the hypothesis that garter snakes, Thamnophis sirtalis, with limited repro...

To explore the nest survival rate of Reeves's pheasant(Syrmaticus reevesii) and the nest-site factors that affect it, we conducted artificial nest experiments with reference to natural nests at Dongzhai National Nature Reserve(DNNR), Henan Province and Pingjingguan, Hubei Province from April to June 2014 simulating the situation in its early and later breeding season. We also determined distanc...

Renesting after nest predation is ultimately an adaptive response to increase productivity in birds. However, renesting also increases reproductive effort to replace lost clutches. We investigated the consequences of this increased reproductive effort by determining whether renesting in female indigo buntings (Passerina cyanea) is associated with a decline in body condition (size-corrected mass...

For many species of lobsters, size at sexual maturity varies across spatially separated populations. This is so for two populations of Caribbean spiny lobster, Panulirus argus, in southern Florida, where females from open-fishing areas around the dry Tortugas mature at a larger size than females from open-fishing areas in the Florida Keys. Variations in onset of maturity between populations of ...

and Implications To increase utilization of artificial insemination by beef producers, estrous and ovulation synchronization protocols must be re-evaluated in an attempt to reduce labor, cost, number of handlings, or a combination thereof without negatively impacting pregnancy rates. One potential way to reduce cost in these systems is through the strategic removal of hormones, such as the cont...

Density-dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central-place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while lit...

This experiment was conducted to determine the effects of interval feeding of whole sunflower seeds on the performance of beef cows and their progeny. During mid to late gestation, 144 multiparous, spring-calving beef cows (588 kg of initial BW; 5.6 initial BCS; 4 to 13 yr old) were individually fed 1 of 3 supplements 4 d/wk for a 76-d period. Supplements (DM basis) included: 1) 0.68 kg of soyb...