Ram effect: Adult rams induce a greater reproductive response in anestrous ewes than yearling rams

2008 ◽  
Vol 103 (3-4) ◽  
pp. 271-277 ◽  
Author(s):  
R. Ungerfeld ◽  
M.A. Ramos ◽  
S.P. González-Pensado
Keyword(s):  
Reproductive Response ◽  
Ram Effect

Overview of the response of anoestrous ewes to the ram effect

2004 ◽  
Vol 16 (4) ◽  
pp. 479 ◽  
Author(s):  
R. Ungerfeld ◽  
M. Forsberg ◽  
E. Rubianes
Keyword(s):  
Post Partum ◽  
Ovarian Response ◽  
Short Length ◽  
Present Review ◽  
Response Patterns ◽  
Endocrine Response ◽  
Lh Pulsatility ◽  
Reproductive Response ◽  
Endocrine Parameters ◽  
Ram Effect

The present review summarises knowledge of the reproductive response of anoestrous ewes to the introduction of rams – in other words, the ram effect. The ovarian and endocrine response, the factors that determine whether ewes will respond or not (associated with both the stimulus and the receptivity of the ewes) and some aspects of practical management are discussed. Information on the use of the ram effect to stimulate post-partum, prepubertal and cyclic ewes is also given. New insights are provided on ovarian response patterns, including recently collected information on luteal responses. The existence of delayed ovulation (5–7 days after the introduction of the rams) followed by luteal phases of normal or short length, luteal cysts and luteinised follicles is reported after scanning the ovaries with ultrasound. Endocrine parameters for depth of anoestrus, such as LH pulsatility and FSH concentrations, and how the concentrations of these hormones should be considered are discussed. Particular attention is paid to the observation of spontaneous, higher LH pulsatility and higher FSH concentrations in anoestrous ewes that respond to rams with luteal phases than in those that fail to respond. The use of progestogen priming and single progestogen administration and the possible advantages for synchronisation of oestrus are also discussed. Other factors that should be considered before the ram effect is applied, such as the strength of the stimulus and some practical considerations, are also included.

Reproductive response and LH secretion in ewes treated with melatonin implants and induced to ovulate with the ram effect

1995 ◽  
Vol 39 (1) ◽  
pp. 23-34 ◽  
Author(s):  
A.Gómez Brunet ◽  
A.López Sebastian ◽  
R.A. Picazo ◽  
B. Cabellos ◽  
S. Goddard
Keyword(s):  
Reproductive Response ◽  
Ram Effect ◽  
Lh Secretion

scholarly journals Whole blood and blood components from vertebrates differentially affect egg formation in three species of anautogenous mosquitoes

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ruby E. Harrison ◽  
Mark R. Brown ◽  
Michael R. Strand
Keyword(s):  
Serum Albumin ◽  
Whole Blood ◽  
Digestive Enzyme ◽  
Vertebrate Host ◽  
Cell Protein ◽  
Blood Components ◽  
Blood Proteins ◽  
Serum Albumins ◽  
Egg Formation ◽  
Reproductive Response

Abstract Background Most female mosquitoes are anautogenous and must blood feed on a vertebrate host to produce eggs. Prior studies show that the number of eggs females lay per clutch correlates with the volume of blood ingested and that protein is the most important macronutrient for egg formation. In contrast, how whole blood, blood fractions and specific blood proteins from different vertebrates affect egg formation is less clear. Since egg formation is best understood in Aedes aegypti, we examined how blood and blood components from different vertebrates affect this species and two others: the malaria vector Anopheles gambiae and arbovirus vector Culex quinquefasciatus. Methods Adult female mosquitoes were fed blood, blood fractions and purified major blood proteins from different vertebrate hosts. Markers of reproductive response including ovary ecdysteroidogenesis, yolk deposition into oocytes and number of mature eggs produced were measured. Results Ae. aegypti, An. gambiae and C. quinquefasciatus responded differently to meals of whole blood, plasma or blood cells from human, rat, chicken and turkey hosts. We observed more similarities between the anthropophiles Ae. aegypti and An. gambiae than the ornithophile C. quinquefasciatus. Focusing on Ae. aegypti, the major plasma-derived proteins (serum albumin, fibrinogen and globulins) differentially stimulated egg formation as a function of vertebrate host source. The major blood cell protein, hemoglobin, stimulated yolk deposition when from pigs but not humans, cows or sheep. Serum albumins from different vertebrates also variably affected egg formation. Bovine serum albumin (BSA) stimulated ovary ecdysteroidogenesis, but more weakly induced digestive enzyme activities than whole blood. In contrast, BSA-derived peptides and free amino acids had no stimulatory effects on ecdysteroidogenesis or yolk deposition into oocytes. Conclusions Whole blood, blood fractions and specific blood proteins supported egg formation in three species of anautogenous mosquitoes but specific responses varied with the vertebrate source of the blood components tested.

scholarly journals Does Habitat Diversity Modify the Dietary and Reproductive Response to Prey Fluctuations in a Generalist Raptor Predator, the Eurasian Buzzard Buteo buteo?

Birds ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 114-126
Author(s):  
Marek Panek
Keyword(s):  
Habitat Quality ◽  
Breeding Success ◽  
Common Vole ◽  
Habitat Diversity ◽  
Crop Fields ◽  
Buteo Buteo ◽  
Nestling Diet ◽  
Reproductive Response ◽  
Agricultural Habitat ◽  
Small Fields

Predators can modify their diet and demography in response to changes in food availability and habitat quality. I tested the prediction that some species can change their predation pattern, between specialist type and generalist type, depending on the complexity of habitat structure. It was hypothesized that their dietary response is stronger in diversified habitats than in simplified ones, but the opposite tendency occurs in the case of reproductive response. The nestling diet and breeding success of the Eurasian Buzzard Buteo buteo, the abundance of its main prey (the common vole Microtus arvalis), and that of the most important alternative prey group (passerines) were estimated over ten years in two types of agricultural habitat in western Poland, i.e., in the diversified habitat of small fields and the simplified habitat of large fields. The vole abundance was higher in large fields, but the abundance of passerines was greater in small fields. The frequency of voles in the Eurasian Buzzard nestling diet was higher in large fields than in small fields and increased with the abundance of this prey in crop fields. However, no difference in the relationship between the vole frequency in the diet of Eurasian Buzzards and the abundance of voles was found between the two habitat types. The breeding success of Eurasian Buzzards was dependent on the vole abundance, but this relationship did not differ between the two field types. It seems that the pattern of dietary and reproductive response of Eurasian Buzzards depends on the actual availability of individual prey species, which can be modified by habitat quality, rather than on relative prey abundance.

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