Midterm 1 Flashcards
Types of growth
Chronological
Physiological
Hyperplasia
Hypertrophy
What is growth
An increase in height, length, girth, and weight that occurs in young animals given adequate feed and water
Measures of growth
- Average daily gain (ADG)
- Days to market
- Cattle 205 day weight (adjusted weaning weight)
- Breeding stock: weight per day of age (WDA)
How to determine ADG
Weight gained over time in days
How to determine adjusted weaning weight
(Weaning wt. - birth weight) over (# of days from birth to weaning) x205+birth wt.
4 factors that effect carcass composition (growth curve)
Nutrition
Gender
Breed
Frame size
Why do we castrate
Boars: meat can have unpleasant aroma
Bulls: dark cutting (looks like it’s freezer burnt)
Easier to control
How do we assess growth
Time from reference point
Live weight at physiological/chronological stages
What is pre weaning growth
Growth from birth to weaning
Dependent on quality of milk produced by dam
What is Post weaning growth
Growth after weaning
Influenced by pre weaning growth rate, genetics, gender, nutrition and environment
What is compensatory growth
“Catch up” growth: when an animal grows more rapidly than normal, after a period of restricted growth, in order to reach normal weight
Growth promotants are used to
Increase growth weight
Improve feed efficiency, reduce other inputs
Change carcass composition
Reduce greenhouse gas emissions
Growth promotants may include
Antimicrobial growth promotants Probiotics Anabolic steroids Enzymes added to feed B-agonists Somatotropin
What is the role of the male reproductive system
Produce genetic material (spermatozoa)
To deliver the genetic material into the right part of the female reproductive system
Hormones- testosterone
Components of male reproductive system
Testes
Epididymis
Vas deferens
Urethra
What are testes
PRIMARY SEX ORGAN
Divided into lobes enclosed by the scrotum
Functions: produce male gametes (spermatozoa), leydig (interstitial) cells produce testosterone
What is epididymis
External duct leading from testes Functions: transport spermatozoa from seminiferous tubules to vas deferens Concentration of sperm Maturation of spermatozoa Storage of spermatozoa (tail)
What is vas deferens
Transport spermatozoa from epididymis to urethra
What is a urethra
Excretory duct for semen and urine
Testes must be ________ degrees colder than body temperature
4-6°
How to maintain lower temperatures in testes
Location
Muscles
Counter current heat exchange mechanism
Sweat glands
How does location keep testes cold
Outside of body cavity away from body heat
How do muscles keep testes cool
Contract and pull scrotum up if cold and down if hot
How does counter current heat exchange mechanism keep testes cool
Blood coming from the heart is cooled by veins to keep testes cool
How do sweat glands keep the testes cool
Increases the amount of evaporative heat loss
What are some accessory glands of the male tract
Vesticular glands
Prostate gland
Bulbourethal (cowpers) glands
Anatomy of male reproductive system 2 parts
Penis
Sigmoid flexure: present in boar, bull and ram, S shaped figure that retracts the penis into sheath for protection
Hormone in male reproductive system and what it does
Testosterone
- Increases spermatozoa production
- Increases muscle synthesis
- Promotes secretion of accessory glands
- Development of secondary sexual characteristics
- Libido or sex drive
Breeding soundness evaluations
Physical exam
Scrotal circumference
Semen evaluation
Libido
Factors that influence breeding soundness
- Age
- Nutrition
- Environmental temperature
- Disease
- Frequency of use
Role of female reproductive system
Produce half the genetic material to produce the offspring
Provide nutrients and protection to the developing fetus
Anatomy of female reproductive system
Ovaries Oviduct Uterus Cervix Vagina Vulva
What are ovaries
PRIMARY SEX ORGAN
Produce ova (female gamete)
Produce female sex hormones
Undergo cyclic changes
What is an oviduct
Carries gametes (spermatozoa and ova)
Site of fertilization
Site of early stages of embryo development
Connects ovary to uterus
What is a uterus
Fertilized egg implants and grows
Produces hormones
Supplies nutrients to embryo and fetus
Contracts to eject fetus
What is a cervix
Thick walled inelastic
Prevents microbial contamination, entry of foreign material
Tightly closed except during estrus (heat) and parturition (birth)
Site of semen deposits during natural mating in sows and mares
Secretions create thick mucous plug during pregnancy
What is a vagina
Organ of copulation
Site of semen deposit during natural mating of cows, does and ewes
Birth canal
What is a vulva
External opening to reproductive tract
Secretes lubricating mucous during heat and parturition
What is monotocous
Normally give birth to one young each gestation
One ovum produced each estrus/heat period
Eg cow and horse
What is Polyocous
Normally give birth to multiple young each gestation
10 to 25 ova produced each estrous cycle
Eg sow, ewe, dog, cat
Purpose of estrous cycle
Releases eggs which are mature enough to be fertilized
Prepare the uterus for potential pregnancy
Ensure that the male will provide spermatozoa at the appropriate time
Ovarian hormones
GnRH
Estrogen
Progesterone (p4)
What is GnRH
GnRH: gonadotropin releasing hormone
Gonadotropins:
FSH: follicle stimulating hormone, stimulates estradiol
LH: causes follicle rupture and releases ova
What is estrogen
Causes reproductive behaviour (peaks prior to heat/estrus)
Promotes secretory activity of the reproductive tract eg. Mucous secretion
What is progesterone (p4)
Inhibits GnRH release
Inhibits reproductive behaviour
Promotes maintenance of pregnancy
Uterine hormone and what is it
Prostaglandin F2a:
Released by the uterus of the ova is not fertilized
Causes the CL to regress so that FSH and LH can be released and new follicles develop
Can inject prostaglandin to do the same thing; used to synchronize estrous in herd
Estrous detection techniques
Animal behaviour
Temperature
Pedometers or other motion detectors
Mount detectors, tail paint/chalk
Anestrus can be caused by
Pregnancy Lactation Presence of offspring Season Stress Pathology
Why use artificial insemination (AI)
Rapid dissemination of superior sires
More extensive use of superior sires
Facilitates cross breeding
Reduction of disease
Improved record keeping
More economical
Safety
Limitations of AI
Possible extensive use of a sire which later shows up poor
Estrous detection is labour intensive
Inability to get good conception rates with frozen boar, ram and stallion semen
Registration restrictions with some breed associations
Lack of technical service in some areas
Estrous synchronization methods
Progesterone method: 7-12 day treatment (89-90% synch rate) administered in feed or water, subcutaneous implants, PRID, patch
Prostaglandin F2a method: inject during days 5-17 of estrous cycle (60-65% conception rate), or 2 injections 12 days apart, regression of CL and return to estrous within 36-72 hours
Three stages of parturition
Relaxation of cervix
Expulsion of fetus
Expulsion of fetal memebranes
Codominance
Both traits are shown
Incomplete dominance
Both are shown but mixed. Black and white make grey
Definition of gene
Basic unit of inheritance consisting of DNA sequence at a specific location (locus) on a chromosome
Definition of chromosome
Are long strands of DNA and associated proteins present in the nucleus of every cell of an organism
Definition of locus
The site of a particular gene on a chromosome. At each locus is a pair of genes, one on the paternal chromosome and one on the maternal chromosome
Alleles definition
Are alternative forms of genes found at a given locus
Epistasis definition
When one pair of genes masks or alters the expression of another pair of genes
Sex-related inheritance categories
Sex-linked
Sex-limited
Sex-influenced
Sex-limited inheritance
Both males and females carry the trait but only one sex shows it
Sex-linked inheritance
The gene is on the sex chromosome, usually X chromosome in mammals
Sex-influenced inheritance
Outcome depends on sex of the animal differs between males and females
Selection tools
EBV: estimated breeding value
EPD: estimated progeny difference
What is complementarity breeding
Improvement of the overall performance of offspring by mating animals with different but complementary breeding values
Ex. Big mate with small to get medium
