Animal Science 4th Exam - livestock and nutrition

Of the six major classes of nutrients, which is the majority of body mass? Which is important of muscle growth? Which two are primary energy sources? Which is most likely to become toxic if fed in excess?

• Majority of body mass: Water

• Important for muscle growth: Protein

• Primary energy sources: Carbohydrates & fats

  • Most likely to become toxic in excess: Fat-soluble vitamins (A, D, E, K)

What is the difference in requirements for protein between ruminants and non-ruminants? What is the difference in requirements for vitamins?

• Protein requirement difference:

  • Ruminants use microbes in the rumen to break down non-protein nitrogen (like urea), so they can synthesize protein.

  • Non-ruminants need high-quality protein with essential amino acids already present in the diet.

• Vitamin requirement difference:

  • Ruminants get most vitamins (especially B and K) from microbial synthesis.

  • Non-ruminants must get most vitamins from their diet.

What are the three major types of digestive systems in livestock (excluding poultry)?

• Three major digestive systems:

  • Monogastric (e.g., pigs)

  • Ruminant (e.g., cattle, sheep)

  • Hindgut fermenter (e.g., horses)

What is the major function of the small intestine? Of the large intestine?

• Small intestine: Absorbs nutrients (amino acids, sugars, fatty acids)

  • Large intestine: Absorbs water, ferments fiber (especially in horses), forms feces

Why does the horse’s need for protein differ from ruminants?

• Horse protein need: Horses can’t use microbial protein well since fermentation happens after the small intestine (in the cecum)

What are the major functions of the rumen?

Major functions of the rumen:

• Fermentation of fibrous feed

• Microbial protein production

• Volatile fatty acid (VFA) production (main energy source)

When converting the amount of dry matter feed to the amount of as-fed feed, which should be larger? If an animal needs 20 pounds of DM, and you are feeding hay that is 90% DM, how much as-fed does the animal need?

Dry Matter (DM) vs. As-fed: As-fed is larger (contains water)

• Calculation: 20 lb DM ÷ 0.90 = 22.2 lb as-fed

Will nutrient concentration (such as percent crude protein) be greater when expressed on a DM basis, or on an as-fed basis?

Nutrient concentration is greater on a: DM basis (because water is removed)

When discussing overall feed value, what is the relationship between crude fiber and crude protein? How would crop residue, good grass hay and legume hay compare?

• Crude fiber vs. crude protein:

  • High crude fiber = lower feed value

  • Crop residue: High fiber, low protein

  • Good grass hay: Moderate fiber & protein

  • Legume hay (like alfalfa): Low fiber, high protein

What are three major factors that affect nutrient requirements of livestock?

• Three major factors affecting nutrient needs:

  • Body size

  • Stage of production (growth, pregnancy, lactation)

  • Environment (weather, stress)

Which stages of production have higher nutrient requirements?

• Higher nutrient needs: Growth, late pregnancy, lactation

Over a yearly production cycle, how do nutrient requirements for a beef cow change? What would a graph of this look like?

• Yearly beef cow needs:

  • Low after weaning

  • Rise during pregnancy

  • Peak at calving and early lactation
    (Graph would show a gradual rise with a peak post-calving)

Which types of feeds will be the most variable in nutrient content?

• Feeds most variable in nutrients: Forages (hay, silage, pasture

What are some examples of “limiting factors” of feedstuffs when determining rations?

• Limiting factors in feed:

  • Low protein

  • High moisture

  • Unbalanced minerals

  • Mold or toxins

Normal consumption for most livestock on maintenance is approximately what percent of body weight?

• Normal livestock intake: About 2-3% of body weight in DM

What is phase feeding? What type of animal would be supplemented with specific amino acids?

➤ Changing the feed based on the animal’s age or stage of production.

What type of animal would be supplemented with specific amino acids?
➤ Monogastrics like pigs and poultry (they need essential amino acids in the diet).

What is the difference between genotype and phenotype?

➤ Genotype is the genetic makeup (DNA).
➤ Phenotype is what we see (traits like weight, color, milk production).

What are examples of simply inherited traits? What are characteristics of them?

➤ Coat color, polled (hornless) vs horned

What are characteristics of simply inherited traits?
➤ Controlled by 1 or 2 genes
➤ Usually show clear categories
➤ Not much affected by environment

Be able to complete a simply Punnet square (for coat color for example.)

➤ For example:

• B = black coat (dominant), b = red coat (recessive)

• Bb x Bb ➝ 25% BB, 50% Bb, 25% bb

• So 75% black, 25% red

What are the characteristics of polygenic traits? What are some examples of polygenic traits that are important in the livestock industry?

➤ Controlled by many genes
➤ Influenced by the environment
➤ Measured on a scale (not just yes/no)

Examples in livestock:
➤ Growth rate, milk yield, fertility, carcass quality

f you know the mean and standard deviation of a population for a given trait, how can you determine if an individual to select is in the top 5 or 1% of the population?

➤ Use a z-score chart (standard deviation away from the mean)
➤ Top 5% = about 1.64 standard deviations above mean
➤ Top 1% = about 2.33 standard deviations above mean

What is selection differential?

➤ The difference between the average of selected animals and the average of the whole population.
(How much better your chosen animals are.)

What does P = G + E mean?

➤ Phenotype = Genotype + Environment
(Traits are shaped by both genes and environment.)

What is heritability? Which types of traits are highly heritable? Which have lower heritability?

➤ How much of the variation in a trait is due to genetics

Highly heritable traits:
➤ Carcass traits, body size

Low heritability traits:
➤ Reproduction, fertility, survival

What is generation interval?

➤ The average age of parents when offspring are born
(Shorter intervals = faster genetic change)

What factors affect the amount of genetic change that can occur per year?

➤ Heritability of trait
➤ Selection differential
➤ Generation interval
➤ Accuracy of selection

What is an EPD? How are they used as a selection tool?

➤ A prediction of how an animal’s offspring will perform compared to others
➤ Used to select breeding stock

What is a selection index?

➤ Combines multiple EPDs into one score based on economic importance of traits

For what types of traits is DNA testing most valuable?

➤ Simply inherited traits
➤ Traits with low heritability (like disease resistance, fertility)
➤ Traits hard to measure early (like feed efficiency)

What is heterosis? How are heritability and heterosis related?

➤ The improvement in traits when crossing different breeds
➤ Offspring outperform parents

How are heritability and heterosis related?
➤ Traits with low heritability benefit more from heterosis

What are the advantages of crossbreeding?

➤ Heterosis
➤ Breed complementarity
➤ Improved fertility, growth, health, and production

What is the difference between a terminal crossbreeding program and a rotational program?

➤ Terminal crossbreeding: All offspring go to market; no replacements kept
➤ Rotational crossbreeding: Females are kept for breeding; rotate sires to keep genetic diversity

Of the six major classes of nutrients, which is the majority of body mass? Which is the important of muscle growth? Which two primary energy sources? Which is most likely to become toxic if fed in excess?

Of the six major classes of nutrients, which is the majority of body mass? - WATER. Which is the important of muscle growth? - PROTEIN. Which two primary energy sources? - CHO + FATS. Which is most likely to become toxic if fed in excess? - MINERALS.

What is the difference in requirements for protein between ruminants and non-ruminants? What is the difference in requirements for vitamins?

Non rum- All essential aminos acids must be suppled in diets

Rum - Specific

What are the three major types of digestive systems in livestock?

Rum + non-rum + non-rum with functional cecum

What is the major function of the small intestine? Of the large intestine?

Small - nutrient absorption + enzymatic digestion

Large - water resorption

Why does the horses need for protein differ from ruminats?

Hindgut fermenter

Protein from microbes is not absorbed

What are the major functions of the rumen?

-fermentation chamver —> microvial digestive

- VFA (Volatile fatty acids) production and vitamin production\

- Physical mixing

When converting the amount of dry matter feed to the amount of as-fed feed, which should be larger? If an animal needs 20 pounds of DM, and you are feeding hay that is 90% DM, how much as-fed does the animal need?

as-fed is ALWAYS larger, 20/.9 = 22.2 lbs as-fed

What nutrient concentration (such as percent cude protein) be greater when expressed on a DM basis, or an an as-fed basis?

Silage - 70% TDN / 100 = 24/5% / 25 —> 24.50 = 100x = 24.5 = x

Ewe needs 4 lbs dm/day, feeding TMR - 60% DM —> 4/.6 = 6.7 lbs as-fed

When discussing overall feed value what is the relationship between crude fiber and crude protein? How would crop residue, good grass hay, and legume hay compare?

Crop residue - low feed value,

Legume - high feed value, lower fiber, higher protein

What are three major factors that affect nutrient requirements of livestock?

• weight

• stage of production - gestation/ lactation -

• performance (ADG

Which stages of production have higher nutrient requirements?

Mature- lactaction, late gestation, young growing

Which types of feeds will be most variable in nutrient content?

Forages, moisture content

What are some examples of “limiting factors” of feedstuffs when determing rations?

-palatability (blood meal)

-handling (beef tallow, molasses)

Normal consumption for most livestock on maintenance is arppox. what percent of body weight?

2-21/2%

What is phase feeding? What type of animal would be supplemented with specfic amino acids?

changing ration often (~2weeks) to meet changing nutrient needs - need with swine the most