Exam 1 Flashcards
Define Growth
An increase in size by the animal
Define hyperplasia
An increase in cell numbers
Define hypertrophy
An increase in cell size
Define compensatory growth
Rate of growth significantly increase after a prolonged feed restriction
Name the 4 phases of a growth curve in order
- Lag phase
- Accelerating phase
- Decelerating phase
- Plateau phase
List 2 factors that can affect the growth curve
- Genetics
- Nutrition
In 3 sentences, describe the mechanism of how compensatory growth happens
Feed restriction causes digestive organs to shrink in size. When organs shrink, maintenance energy requirements are decreased. This decrease results in greater feed efficiency
Draw the growth curve and the curve for compensatory growth
Draw and label the growth curves for bone, muscle, and fat tissue
What is considered the gold standard for estimating body composition of cattle?
Comparative slaughter
Describe the method of how comparative slaughter is done in 3 sentences
A group of similar animals are slaughtered together at different stages of growth curve to estimate changes in body composition. Each carcass is put in a grinder and made into a paste. The paste is sent to a lab for nutrient analysis.
Describe the method of how carcass dissection is done in 1 sentence
Dead animal carcass is cut with a butcher knife to separate bone, muscle, and fat tissue
Write one disadvantage of the carcass dissection method
Fails to measure internal marbling fat
Describe how the sawdust method is done in 2 sentences
Animal carcass is frozen and a saw is used on frozen carcass. Sawdust is then collected and subjected to lab procedures for nutrient analysis
In 3 sentences, describe how DEXA estimates body composition
The animal is exposed to x-rays at 2 different wavelengths. Each tissue in body absorbs radiation differently. The amount absorbed by different tissues is used in math formulas that estimate % of each tissue.
Write 1 advantage of the DEXA method
The animal is alive and multiple measurements can be taken along growth curve
Write 1 advantage and 1 disadvantage of using CT scans to estimate body composition
+ ~ most accurate
- ~ expensive equipment
In 2 sentences, explain how K-40 is used to estimate body composition
It is a form of K that is a radioactive isotype which makes it less common. It is soluble in water so the more muscle you have, the higher the K-40
In 2 sentences, explain how the Deuterium dilution technique is used to estimate body composition
A known amount of Deuterium is injected into the blood. After 24 hours, the amount of Deuterium is measured in blood.
More muscle = less deuterium
In 2 sentences, explain how electrical conductivity can be used to estimate body composition
An electrical current is put on the animal and conduction of electricity by body is measured. Animals with more muscle conduct more electricity
In 2 sentences, explain how ultrasound can be used to estimate body composition
A probe is waved on animal skin and emits sound waves which is used to generate a 3D image. Bone has the most dense, then muscle, then fat
What is your favorite method of estimating body composition. Explain why.
Describe the process of prenatal development starting with the zygote and ending with the fetus. WILL GIVE US A CHEAT SHEET. JUST HAVE TO COPY ONTO TEST
- After reproduction, zygote is formed by a sperm fertilizing an egg
- The zygote divides into 2 cells, then 4, and so on until 32 cells are formed. Between 4 and 8 cell stages, the cells are called a blastomere
- At 32 cell stage, zygote forms into a morula
Day 4 of pregnancy - On day 5, the morula moves into uterus and undergoes morphogenesis
- On day 6, the morula becomes a new structure, blastocyst
- On day 8, implantation occurs, the blastocyst is pushed into uterus lining (endometrium) of pregnant female.
- On day 10, the blastocyst changes shape again and becomes the embryonic disk
- On day 21, gastration occurs and continues until day 63 of pregnancy
- Prenatal development continues until the 9th month of pregnancy
Name the 3 germ layers of the embryo and list 2 tissues types or organs that arise from each layer
Ectoderm - skin and mammary tissue
Mesoderm - muscle and fat tissue
Endoderm - digestive and respiratory organs