Lecture 21: Beef Cattle Nutrition 1

beef cows are NOT:

small, unproductive dairy cows

• beef are scavengers

• dairy cow are foragers

key point: beef cows rely on forage and body reserves; fairy cows are managed for maximal nutrient throughout

dairy cow vs beef cow, know the difference!

cow-calf operations —> then go to:

backgroundings/stocker —> finishing

goal of cow-calf operations:

produce healthy weaned calves

stocker goals:

grow frame/lean tissue

finishing goals:

maximize carcass value

stocker operations›

background operations

finishing/feedlot operations

beef production phases

cow-calf operations are:

small-large scale

permanent herd

• replacement heifers, bull calves will be sold

produce feeder calves for downstream production systems

• sold —> stocker/background

big goals of cow-calf operations

maximize calves weaned

maintain reproductive efficiency

minimize morbidity/mortality

minimize overwintering cost

produce marketable calves

technology use increases with what?

operation size!

technology use otherwise known as

NAHMS

Examples of tech use with operation size in beef cattle

palpation/semen evaluation (around 20%)

embryo transfer (around 3 percent)

NAHMS beef study

key performance indicators

key point on beef performance indicators:

deviations often indicate nutritional or repro issues

what should be the weaning weight of beef calves?

around 50% of cow’s BW

additional herd metrics

weaning age: around 180 days

cow longevity: 7-8 years

culling rate: 5-10%

profit vaires with herd size

weights throughout production

bith —> weaning —> feedlot —> carcass

dressing percentage:

hot carcass weight/live weight —> will decrease further by 2-4% once carcass is chilled

beef cattle weight

live cow weight to chilled carcass:

backgrounding/stocker systems

for newly weaned calves not ready for the feedllot

enter at 700-800 lbs

goal: lean growth, not fat

key point of backgrounding/stocker systems

nutrition prioritizes protein and moderate energy

transition to nutrition: what nutrients drive these performance outcomes?

nutrient categories:

• energy

• protein

• minerals

• vitamins

energy requirements for beef cattle:

net energy for maintenance (Nem)

• basal metabolism

• environmental adjustments

net energy for production (NEg)

• weight gain - lean vs fat

• body condition gain

• fetal growth

• milk production

which component of protein is associated with energy requirements in beef cattle?

degradable intake protein (DIP)

beef cattle energy diagram

protein overview for beef cattle

CP —> DIP (RDP) + UIP (RUP)

DIP (RDP) —> used by microbes (need N) —> microbial crude protein (MCP)

• DIP associated with energy requirements of microbes —> energy needed for microbes to utilize DIP

MCP + UIP (RUP) —> MP (metabolizable protein)

key point: MP is what the animal actually uses

the rumen and protein

protein requirements for beef cattle

driven by average daily gain (ADG)

growing animals —> higher MP demand

major minerals for beef cattle

calcium

• high in forages

• low in grains

phosphorus

• high in grains and corn by-products

• low in forages

key point: Ca:P imbalance (high P diet) —> urinary calculi

other macro minerals to know about for beef cattle

Mg —> grass tetany

• low in spring grass

Na —> supplementation needed

K —> high in forage

S —> toxicity risk

trace minerals and vitamins

trace minerals:

Co, Cu, I, Fe, Mn, Se, Zn

supplement!
- loose mineral or block

vitamin requirements:

vitamin A, D, E supplemented

note: rumen synthesizes most B vitamins and K vitamins

• some B vitamins may need to be supplemented for stressed calves at weaning

applied nutrition - which factors affect requirements?

• stage of production

• environment

• body condition

• breed/size

stage of production

gestation

lactation (supplementation of energy and CP necessary)

• average forage is deficient in energy for about 6 months post-calving

• average forage is deficient in CP for 3-4 months post-calving

maintenance

key point: lactation = highest nutrient demand

environemental effects

cold —> increased energy

heat —> decreased intake

• most on grain, less dramatic on forage

thermoneutral zone

• energy is not expended to maintain mody temp

• cattle = 32-77 degrees

• maintaining depends on BCS, haircoat, if haircoat wet, dry, or muddy

summary for cattle nutrition 1

• production system determines nutritional strategy

• energy and protein drive performance

• minerals prevent major disease issues

• requirements are dynamic