Nutrition and reproduction the sheep model
Download
1 / 59

Nutrition and reproduction - PowerPoint PPT Presentation


  • 467 Views
  • Uploaded on

Nutrition and reproduction – the sheep model. Stewart M. Rhind. Why are nutrition-reproduction relationships important?. Wild animals – exploiting food resources to the full – e.g. clutch size in birds - more food means = more eggs = more young reared.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Nutrition and reproduction ' - Philip


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Why are nutrition reproduction relationships important l.jpg
Why are nutrition-reproduction relationships important?

  • Wild animals – exploiting food resources to the full – e.g. clutch size in birds - more food means = more eggs = more young reared.

  • Domestic animals –More offspring = more money!


Why sheep l.jpg
Why sheep?

  • Economically important

  • Much is known of their physiology

  • Reproductive performance is closely related to nutrition in some breeds

  • Can be used to investigate underlying mechanisms


A few basic facts l.jpg
A few basic facts

  • Ewes typically breed once per year, in the autumn and produce 1 to 4 lambs

  • Ewes (and females of many other species) are “designed” to gain and lose large fat reserves

  • The fat reserves have to “speak to” the ovaries!


When and how does nutrition determine reproduction l.jpg
When and how does nutrition determine reproduction?

  • Number of eggs produced.

  • Number of embryos that survive.

  • Reproductive performance can be adjusted at EVERY stage

    - during gestation

    - before gestation

    - before the mother is born!



When does nutrition determine lambing rate l.jpg
When does nutrition determine lambing rate?

  • During gestation – loss of embryos


Embryonic loss l.jpg
Embryonic loss

Nutrition effects :

  • Undernutrition during first month of gestation can increase embryo death rate

  • Overnutrition during first month of gestation can increase embryo death rate


Embryonic loss9 l.jpg
Embryonic loss

Other causes of increased loss:

  • Parity (higher in first)

  • Simultaneous lactation

  • Heat and cold stress

  • High ovulation rate (breed or hormonal treatment)


When does nutrition determine lambing rate10 l.jpg
When does nutrition determine lambing rate?

  • During gestation – loss of embryos

  • Days, weeks, months and years before mating – ovulation rate


Slide15 l.jpg
Short term intake effects and medium term body condition effects are NOT expressed through the same physiological mechanisms


Body condition l.jpg
Body condition

Numbers of large, potentially ovulatory, ovarian follicles at 48h before ovulation :

High body condition (HBC) 4

Low body condition (LBC) 2


Intake l.jpg

Numbers of large, potentially ovulatory, ovarian follicles at 48h before ovulation :

NOT affected by level of food intake

…..and so …..

Intake


Hypothetical ewe l.jpg
Hypothetical ewe at 48h before ovulation :

HBC HI 4 LF 4 ovulated

HBC LI 4 LF 3 ovulated

LBC HI 2 LF 2 ovulated

LBC LI 2 LF 1 ovulated


Slide19 l.jpg

If there is at 48h before ovulation :only one large follicle present, it doesn’t matter how good the premating nutrition is, there cannot be more than one ovulation!



Slide22 l.jpg

Probably by the ewe?LH pulse frequency during the 3 days before ovulation – high intake = more frequent pulses- low intake = less frequent pulses


Slide23 l.jpg

BUT this ewe?difference in LH pulse frequency operates against a background of different nutrient and hormone signals within the follicle (leptin? )


When does nutrition determine lambing rate24 l.jpg
When does nutrition determine lambing rate? ewe?

  • During gestation – loss of embryos

  • Days, weeks, months and years before mating – ovulation rate

  • Before the ewe is born

  • ……before the ewe is conceived (?!)



It s not about l.jpg
It’s NOT About… performance.

  • Contemporary body condition

    - thin animals produce fewer offspring (sheep) or breed later (postpartum cattle)

  • Pre-mating nutrition

    - higher feed intakes before mating results in more offspring


Slide27 l.jpg

It is certain that the significance of correct nutrition in child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

Edward Mellanby (1933) Lancet ii, 1131-1137


Slide28 l.jpg

WHEN? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • using this to illustrate the diversity of mechanisms through which nutrition can operate

  • same fundamental mechanisms may operate to control reproduction in the adult animal


Late pregnancy lactation l.jpg
Late Pregnancy / Lactation child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • 100 days 100 days Post Proportions :

  • before birth after birth -weaning Single/ Twin

  • __________________________________________________

  • No supplement Supplement Normal 0.43 / 0.54

  • Supplement No supplement Normal 0.46 / 0.57

  • No supplement No supplement Normal 0.57 / 0.43

  • __________________________________________________

  • Gunn et al. (1995)


Mid pregnancy l.jpg
Mid-pregnancy child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Effects on gonad structure and function

  • (Rae et al. (2001, 2002)


Early pregnancy 0 11 days l.jpg
Early Pregnancy (0 - 11 days) child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.


Associated ontogeny l.jpg
Associated Ontogeny child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.


Slide34 l.jpg

HOW? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.


Slide35 l.jpg
How? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Nutrient delivery


Nutrient delivery l.jpg
Nutrient delivery child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

Maternal Undernutrition

Maternal Overnutrition

Normal Placenta

Small Placenta

Litter “Runt”

All affect reproductive development


Slide37 l.jpg
How? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Nutrient delivery

  • Endocrine signals


Slide38 l.jpg

Endocrine signals child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

Maternal Undernutrition

Maternal Overnutrition

Normal Placenta

Small Placenta

All change with nutritional state

All directly affect gonad function

All present and active in brain


Other candidates l.jpg
Other Candidates child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Growth hormone

  • Cortisol

  • Glucagon

  • Prolactin

  • Ghrelin

  • Progesterone

  • Etc.


What evidence is there that l.jpg
What Evidence Is There That… child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • early life nutrition can alter profiles of these hormones

  • the hormones can affect reproductive development


Slide41 l.jpg

  • Gallaher et al. (1998) – early child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.fetal undernutrition altered profiles of IGF-1, IGFBP-3 and responses to ACTH, later

  • Rae et al (2002) – undernutrition reduced T3 concentrations in fetus and ewe.

  • Augustin et al. (2003) – exposure of bovine blastocysts to insulin increased cell number and cleavage rate and decreased the number of apoptotic bodies


Slide42 l.jpg
How? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Nutrient delivery

  • Endocrine signals

  • Structure and physiology


Type 2 follicles mm 2 110d fetus l.jpg

Structure and Physiology child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

Type 2 follicles /mm2 - 110d fetus


Slide44 l.jpg
How? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Nutrient delivery

  • Endocrine signals

  • Structure and physiology

  • Reproductive behaviour


Reproductive behaviour effects l.jpg
Reproductive Behaviour Effects? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Normal:

  • Offspring of undernourished ewes:

• Demasculinisation of some non- reproductive behaviours

• By extrapolation - reduced sexual capacity?


Slide46 l.jpg
How? child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Nutrient delivery

  • Endocrine signals

  • Structure and physiology

  • Reproductive behaviour

  • Cellular level effects


Effects at cellular level l.jpg
Effects At Cellular Level child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Effects can be expressed on very early embryos


Effects at cellular level48 l.jpg
Effects At Cellular Level child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Effects can be expressed on veryearly embryos

  • Modified expression of multiple genes


Slide49 l.jpg

Effects At Cellular Level child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

  • Effects can be expressed on veryearly embryos

  • Modified expression of multiple genes

  • DNA methylation altered by nutrition


Slide50 l.jpg

Effects At Cellular Level child-bearing does not begin in pregnancy itself or even in the adult female before pregnancy. It looms large as soon as a female child is born and indeed in its uterine life.

Gene

Nutrition

Methylation 1

Methylation 2

F1 Gene expression altered

Gene expression altered

F2 Gene expression unaltered

Gene expression altered

F3 Gene expression unaltered

Gene expression altered


Slide51 l.jpg
Transgenerational effects mean that the reproductive performance of animals is determined before they are conceived!


Additional effects l.jpg
Additional effects performance of animals is determined

  • Reproductive function

  • Altered thyroid function


Additional effects54 l.jpg
Additional effects performance of animals is determined

  • Reproductive function

  • Altered thyroid function

  • Increased cardiovascular disease


Additional effects55 l.jpg
Additional effects performance of animals is determined

  • Reproductive function

  • Altered thyroid function

  • Increased cardiovascular disease

  • Altered neuroendocrine development


Male offspring more nervous l.jpg
Male offspring more nervous performance of animals is determined


Additional effects57 l.jpg
Additional effects performance of animals is determined

  • Reproductive function

  • Altered thyroid function

  • Increased cardiovascular disease

  • Altered neuroendocrine development

  • Impaired glucose tolerance / diabetes


Impaired tolerance in late adult life l.jpg
Impaired tolerance in late adult life performance of animals is determined


Conclusions l.jpg
Conclusions performance of animals is determined

  • In female sheep, nutrition of both the fetus and adult can influence reproductive performance

  • Many different physiological mechanisms are involved

  • Effects may be exerted at one time and expressed at another


ad