ANSC exam 3 Reproduction + Pregnancy

Puberty is determined by?

Body size rather than age

Cyclicity and Fertility are determined by?

Energy status

Faster growth =

earlier age at puberty

What hormone is key to puberty onset and cyclicity?

Leptin 

What produces leptin?

adipocytes and increased with fat reserves

What does leptin do

acts on neurons releasing GnRH from the hypothalamus 

What does GnRH do

releases FSH and LH which act on gonads which then release sex steroids

ob/ob mouse is sterile and has adequate reserves but the brain does not know that why?

because ob/ob has a leptin deficiency so never sexually matures 

Females will stop cycling if?

they do not have sufficient energy reserves to sustain pregnancy and lactation in the face of food shortage 

Pregnancy is a committed step so that means?

without sufficient nutrients a females body will not want to get pregnant 

Effect of nutritional status ranges from absolutely sterility to maximal fertility 

lower population = more food and less fertility 

more food = population and fertility increase 

Energy availability is most important for

cyclicity, but lack of other nutrients can reduce fertility

Ex. food supply limits reproductive rate thus population size in many wildlife species 

Capital breeders

Their nutrient requirement to start reproduction is found in “savings” in adipose tissue where they pull from during the pregnancy 

Income breeders

Their nutrient requirement to start reproduction is found through daily energy inputs essentially eating more during their pregnancy 

Nutrition can impact what in a male

spermatogenesis but it rarely leads to complete infertility

Over nutrition leads to excess

insulin and leptin

excess insulin and leptin can cause

lower testosterone

stress and dysfunction to cells in testis 

negative effects on sperm quality 

What type of energy balance do dairy cows have during lactation?

Negative, their loss in body fat results in delayed cycles and lower fertility

Reproductive tissues take what priority

First priority (high)

Metabolic impact of pregnancy depends on what?

Gestational length and % of bodyweight

Fetal growth and energy requirements accelerate when?

The third trimester, because this is when most growth occurs

Maternal diet can change?

DNA methylation which can change phenotype (no food inside can make hoard outside)

Undernutrition in utero has lasting impacts like?

Decreased birthweight 

increases age at first conception 

Increases obesity and insulin resistance (thrifty)

2 phases across pregnancy

Anabolic(building) Catabolic(breaking down)

Anabolic phase of pregnancy

normal to increased insulin sensitivity

Insulin action to store fuel is facilitated by estrogen and progesterone 

Glycogen is synthesized and stored in liver and muscle 

lipogenesis builds fat reserves 

Enhanced protein synthesis

Growth of breasts, uterus, and essential musculature of the mother

Catabolic phase of pregnancy

Maternal insulin resistance

Maternal utilization of glucose and amino acids slows to allow transport of fetus 

Accelerated growth of fetus, placenta, and fluids

Accelerated lipolysis to provide fuel for the mother 

Placental hormones are responsible for insulin resistance and lipid mobilization 

Example of the 2 phases of pregnancy

sheep gain body fat in earl pregnancy, and then lose it during late pregnancy when fetal requirements are very high

Maternal choline supplementation can improve offspring performance

this helps feed the fetus