Reproduction Nutrition Development 

About: Reproduction Nutrition Development is an academic journal. The journal publishes majorly in the area(s): Rumen & Insulin. It has an ISSN identifier of 0003-388X. Over the lifetime, 2388 publications have been published receiving 45317 citations.

Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults.

Abstract: The principal biological role of α-linolenic acid (αLNA; 18:3n-3) appears to be as a precursor for the synthesis of longer chain n-3 polyunsaturated fatty acids (PUFA). Increasing αLNA intake for a period of weeks to months results in an increase in the proportion of eicosapentaenoic acid (EPA; 20:5n-3) in plasma lipids, in erythrocytes, leukocytes, platelets and in breast milk but there is no increase in docosahexaenoic acid (DHA; 22:6n-3), which may even decline in some pools at high αLNA intakes. Stable isotope tracer studies indicate that conversion of αLNA to EPA occurs but is limited in men and that further transformation to DHA is very low. The fractional conversion of αLNA to the longer chain n-3 PUFA is greater in women which may be due to a regulatory effect of oestrogen. A lower proportion of αLNA is used for β-oxidation in women compared with men. Overall, αLNA appears to be a limited source of longer chain n-3 PUFA in humans. Thus, adequate intakes of preformed long chain n-3 PUFA, in particular DHA, may be important for maintaining optimal tissue function. Capacity to up-regulate αLNA conversion in women may be important for meeting the demands of the fetus and neonate for DHA. n-3 polyunsaturated fatty acids / humans / α-linolenic acid / metabolism

The minerals of milk.

Abstract: The salt of milk constitutes a small part of milk (8-9 g.L(-1)); this fraction contains calcium, magnesium, sodium and potassium for the main cations and inorganic phosphate, citrate and chloride for the main anions. In milk, these ions are more or less associated between themselves and with proteins. Depending on the type of ion, they are diffusible (cases of sodium, potassium and chloride) or partially associated with casein molecules (cases of calcium, magnesium, phosphate and citrate), to form large colloidal particles called casein micelles. Today, our knowledge and understanding concerning this fraction is relatively complete. In this review, the different models explaining (i) the nature and distribution of these minerals (especially calcium phosphate) in both fractions of milk and (ii) their behaviour in different physico-chemical conditions, are discussed.

Dietary lipids and forages interactions on cow and goat milk fatty acid composition and sensory properties

Abstract: This review summarises the known effects of dietary factors on bovine and caprine milk fatty acid composition, as well as the regulation of cow and goat mammary lipid secretion. Special attention is given to fatty acids that could play a role for human health, such as saturated fatty acids, oleic acid, n-6- or n-3-C18 to C22 polyunsaturated fatty acids, trans isomers of C18:1 and C18:2, and isomers of conjugated linoleic acid (CLA). The main dietary factors taken into account are the nature of forages, including pasture, the forage:concentrate ratio and diet starch content, and the supplementation of dairy rations with crude or processed vegetable oils or oilseeds, and vitamin E. A particular emphasis is given to studies on interactions between these dietary factors, which show that there is a considerable plasticity of ruminant milk fatty acid composition. Despite the existence of several studies on the effects of dietary factors on the sensorial quality of milk and dairy products, there is a need to evaluate more deeply how the different feeding strategies could change the nutritional, sensorial and technological aspects of milk fat quality. dairy cow / dairy goat / forages / oilseeds / milk / fatty acids / human health

Spermatogenesis and spermatology of some teleost fish species

Abstract: In teleost fish, the whole of the processes involved in the formation of spermatozoa and their release and in fecundation are extremely diverse Two main types of testicular structure are distinguished : a tubular and a lobular Theorganization of the lobules and genital duct structure is very diverse in the latter type Spermatogenesis can be continuous, as in guppy, discontinuous with overlapping cycles, as in carp, or show well separated cycles as in trout Spermiogenesis shows increasing degrees of complexity, leading to the formation of extremely simple spermatozoa as in carp (spherical head, very little nuclear histone transformation, very simple mid-piece with untransformed cytoplasmic and mitochondrialremains) or much more complex spermatozoa as those of guppy (elongated head, histoneprotamine transformation, transformation of the centriolar complex in the deep nuclear notch, very developed mid-piece with glycogen stores) Spermatogenetic production is extremely variable (GSI : 01-10 % ; annual production : 1 $ 10 to 7 910 spermatozoa/g body weight) Spermiation yield varies according to species but also within the same species (20-90 % in trout) The endocrine model of spermatogenesis and spermiation is very different in carp and trout The main environmental factor influencing spermatogenesis is photoperiod in trout and temperature in carp ; spermiation depends on temperature in trout and on social environment as well as temperature in carp Sperm physiology (survival time in vivo and in vitro, motility time, metabolism) is very different in the several species studied Two groups with a fundamentally different physiology (internal or external fecundation), sperm biology and morphology (structure of testis and spermatozoon) can be grossly distinguished These groups are fish with lobular testes (guppy) and those with tubular testes (teleosts)

A review of the effects of supplementary nutrition in the ewe on the concentrations of reproductive and metabolic hormones and the mechanisms that regulate folliculogenesis and ovulation rate.

Abstract: This paper discusses the phenomenon of nutritional flushing in ewes whereby increased nutrition stimulates folliculogenesis and ovulation rate. In addition the paper reviews recent findings on the effects of increased levels of nutrition on the blood concentrations of reproductive and metabolic hormones in the ewe and some of the intraovarian changes that take place in response to nutritional stimulation. Finally, in the paper, we propose a model of the physiological mechanism for the nutritional stimulation of folliculogenesis and we review how closely the model fits recent published and unpublished evidence examining the mechanism of flushing. Nutritional stimulation alters the blood concentrations of some metabolic hormones. By using short-term models of nutritional flushing, we have shown that as the blood concentrations of insulin and leptin increase that of growth hormone decreases while that of IGF-I appears unaffected by the nutritional flushing. Nutritional flushing also alters the blood concentrations of some reproductive hormones. Again, using the same model, we have shown that there is a transient increase in FSH and a decrease in oestradiol concentrations in the blood. The changes in oestradiol are particularly evident in the follicular phase of the oestrous cycle. In the ovary, the effect of nutrition is to stimulate folliculogenesis. These changes are associated with intra-follicular alterations in the insulin-glucose, IGF and leptin metabolic systems. The stimulation of these intra-follicular systems leads to a suppression in follicular oestradiol production. The consequence of these direct actions on the follicle is a reduced negative feedback to the hypothalamic-pituitary system and increased FSH secretion that leads to a stimulation of folliculogenesis.