Factors Affecting Growth Lecture Flashcards
Animals grow according to interactions between
genes they inherit and the environmental factors they are exposed to
Genotypic factors affecting growth
species
breed
sex
environmental factors affecting growth
stress
nutrition
disease
activity
Heredity
process of passing along genes from one generation to the next
Genetic differences come about through
evolution which results from selection of mutations that arise in genes
Genotype refers to
unique set of genes that an animal possesses in its genome
Heritability values
reflect the ability of the animal to pass a particular trait to the next generation
H>0.5
highly heritable trait
0.2<H<0.5
moderately heritable trait
H<0.2
low heritable trait
Traits associated with carcass composition are
moderately heritable
Species
refers to organisms capable of interbreeding and producing fertile offspring
Growth between species varies in
deposition of different tissues
relative proportion of each body part
Relative distribution of muscle main points
wild species have greater % of muscle located in upper portion of hind legs- enhances speed and agility
Domesticated ruminants- greater proportion in abdominal muscles for extensive rumen
Species muscle distribution of pigs
increased muscles around spinal column-used for rooting action
Ruminants have increased muscle in
front legs to bear weight associated with grazing for long periods of time
abdominal muscle for rumen
Breeds
within a species, breeders have placed selection pressure on different traits that have led to many different breeds
To determine frame size a _____ is given for a particular age range
frame score
Large framed cattle reach heavier weights at a given __________ maturity
compositional or physiological
Large framed cattle take longer to
reach mature weight
later maturing animals
Small framed animals grow
quickly
early maturing
At the same chronological age large-framed animals are physiologically ____ than small-framed animals
younger
If comparisons are made at the same chronological age or same weight, later maturing animals are _____, while earlier maturing animals are ______ and more physiologically mature
leaner
fatter
If cattle are compared at the same physiological or compositional endpoint they are considered
compositionally equivalent
Selection for muscle is _____ related to milk production
inversely
Animals used for milk are less
muscular
Selection has not changes muscle
distribution
Selection for muscle is ______ related to wool production
inversely
meat breeds of sheep have superior conformation as measured by ____
muscle:bone ratios
amount of meat per unit of bone
Wool breeds are _____ framed
larger
Selection for muscle is _______ related to ability to conceive and produce milk for young
inversely
Intact males are capable of higher ____ than castrates and females
body weights
Intact males attain compositional maturity at ____ chronological ages than castrates and females
later
Intact females mature ______ of sex classes, whereas castrates are _____
earliest
intermediate
exception to females being early and castrates being intermediate
Pigs
gilts mature later and reach heavier weights than barrows
Intact males have ____ proportion of muscle located in forequarter, specifically in neck and thorax
greater
increased _____ binding receptors are why intact males have greater proportion of muscle located in forequarter
androgen
females have increased proportion of muscle in
pelvic limb and abdominal wall
Males have large muscle fiber _____ than females and castrates
diameters
Estrogen stimulates ________
epiphyseal plate closure
so males tend to be taller- long bones grow more before closure
Both estrogens and androgens in crease
periosteal bone growth (bone thickening) but androgen more-males have thicker bones than females
Why do females fatten sooner
decreased long bone growth due to increased estrogen
muscle growth starts to decrease and more nutrients available for fat
Growth and development depends on the levels of essential nutrients in the diet including
Fatty acids
amino acids
carbs
vitamins
minerals
Consuming nutrients in excess of maintenance requirements allows for
growth
production
reproduction
balance of nutrients consumed determines the
composition of growth
Nutrient requirements
maintenance requirements
growth requirements
production requirements
Nutrient partitioning
utilization of nutrients is partitioned among various tissues and organs according to their physiological importance
Highest priority to lowest priority for nutrient partitioning
Organ systems- nervous, circulatory, respiratory, digestive, repro
Tissues-skeleton, muscle, adipose
Adipose deposition- mesenteric, perirenal, subcutaneous or intermuscular, intramuscular
Conditions of altered nutrient partitioning
pregnancy
transition from non-lactating to lactating
Types of energy balance
positive- nutrients are plentiful
negative- intake not sufficient to meet needs
compensatory growth
animal’s growth after a period of nutritional stress
rate of growth is often greater than exhibited by a genetically identical animal during normal growth
how are abnormally high growth rates achieved so that nutritionally compromised animals can catch up
low basal metabolism during nutrient restriction due to decreased visceral weight
increased feed intake during realimentation contributes to increased growth
Nutrient restriction can be severe enough to
delay catch-up period
Very severe starvation can _______ growth
permanently stunt
enhances onset of fattening
Nutrient restriction ____ in growth can result in _____ effects, which are greatest on ________ and less on _______
early
long-lasting
early maturing (bone)
late maturing (fat)
___ and ____ must be considered together when discussing dietary protein
quantity
quality
dietary protein is more important in what type of animals
monogastric
Diets with sufficient energy but insufficient protein for tissue deposition results in
increased fat deposition
Muscle protein accretion rates vary between
breeds, sexes and with physical activity and growth enhancers
Animals with increased muscle protein accretion rates that require more protein include
genetically selected animals
working animals
males
hormone
energy is required for
maintenance and for growth of new tissue
Energy required for maintenance _____ with size
increases
Optimal energy levels for food animals can be determined by
increasing dietary energy intake to a point where lean muscle gain is maximized
when energy is partitioned to fat it
reduced feed conversion
Energy requirements for growth depends on
genetics
sex class of animal
location on growth curve
hormone treatments for growth enhancement
Animals contain _____ microbial cells than animal cells
> 10x
What improves growth rate and feed efficiency when concerning microorganisms
better sanitation
Why does exposure to microbes result in reduced performance
nutrient and energy cost of immune response required to protect against microbes takes resources away from growth
Breeding for growth and performance has ______ against immunity
inversely selected
strategies to limit the effect of microorganisms on growth and performance
high level biosecurity for farms
feeding diets that contain sufficient nutrients to maintain a healthy immune system
vaccinations
antibiotic treatments to reduce bacterial load
Old way to use antibiotics
added at very low concentrations to animal diets as growth promoters
what has negated the effects of antibiotics for pig performance
modern hygiene and management practices
Physical and social stresses significantly affect the
hypothalmo-pituitary-adrenal axis
chronically stressed animals suffer from elevated circulating concentrations of
glucocorticoids that inhibit growth
transportation stress includes
temperature and wind
novel social group
absence of feed and water
motions
Housing stress is associated with
introducing new animals into a new social order so that a new social hierarchy needs to be established
Type of housing that reduces stress on animals
specific-stress-free housing
rearing animals in groups from weaning to slaughter results in
reduced injuries and improved growth
Physical activity is
any body movement that works your muscles and requires more energy than resting
It requires what to move muscles and supply oxygen
energy
Available energy reserves
body fat
muscle fat
muscle carbs
liver carbs
Energy supply for short term exercise (8-10 seconds)
phosphagen system
Source for phosphagen system
ATP in muscle
Energy supply for medium exercise (1.3-1.6 minutes)
Glycogen-lactic acid system
Source for glycogen-lactic acid sysstem
muscle and liver glycogen converted to glucose and then lactic acid for anaerobic respiration
Energy supply for long term exercise
aerobic respiration
source for aerobic respiration
complete oxidation of glucose and fatty acids from muscle, liver and adipose
How does physical activity impact muscle protein synthessis
resistance exercise increases protein synthesis
endurance exercise may decrease synthesis if insufficient dietary energy and protein is available
How does exercise impact bone
increases bone mass, density and size
Exercise before maturity does what to bone mass
increases peak
Exercise induces release of what
GH and IGF-1
GH is secreted in a
pulsatile fashion after exercise
Amount of GH release depends on
exercise intensity
GH release with exercise is greatest in ______ and can significantly impact _______
adolescence
body size and composition
After middle age exercise induces
much less GH
