Growing Beef Cattle

Question 1

Ingested plant material:

Answer 1

• VFAs
• microbial protein
• RUP
• indigestible OM

lignin affects fiber digestibility

Question 2

Carbohydrates

Answer 2

CHOs 🡢 Hexose 🡢 2 pyruvate 🡢
1) 2 acetyl CoA 🡢 2 acetate + 1 butyrate
2) 2 propionate
3) 2 lactate 🡢 2 proprionate

Question 3

Energy calculated from:

Answer 3

ADF/NDF

Gross Energy 🡢 fecal loss (ingiestible)
🡣
Digestible Energy 🡢 urinary loss + gaseous loss (methane)
🡣
Metabolizable Energy 🡢 heat loss
🡣
Net Energy 🡢 NE-maintenance, NE-gain, NE-lactation

Question 4

Protein

Answer 4

Crude protein = Total N x 6.25

Question 5

Growing Phase V Finishing Phase

Answer 5

Growing Phase
weaning (~500 lbs) until ~800lbs
lean body deposition (bone + muscle)
efficienct growth phase
diet 🡩 $/lb (higher protein)

Finishing Phase
- ~800 lbs to ~1350 lbs
- high energy diet, fattening
- less efficient
- diet less expensive
- finished when ADG is 🡣 + ~28% body fat (BCS 7-8)

average daily gain = 3.5lb/day

Question 6

Fiber Requirement

Answer 6

~27% NDF to maintain normal rumen
- reasonable in growing phase, not in finishing

~7-10% peNDF
- not done in many feedlots

Effects of acidosis in feedlot?
- changes intake patterns
- liver abseccess
- feed efficiency?

Question 7

prime directive

Answer 7

sell a group of animals for more than your total costs to acquire + feed them

cost of gain
- ingredient cost
- feed efficiency 🡢 conversion of feed to tissue

Feed : Gain 🡢 4:1 for ~500lbs, 7 : 1 for 800 lbs+

Question 8

Transitioning + Adaptation

Question 9

Starting cattle on feed

Answer 9

Supplemental hay:
- FC to start
- 🡣 hay offered as starter diet intake 🡩
- eliminate by 5-10 days

Start diet offered based on appetite:
- expect to start at 1-1.5% BW intake
- 🡩 to ~2.0% BW over 2 weeks
- 🡩 from 2% to ~2.5% BW by 3-4 wks

Question 10

Rumen Adaptation

Answer 10

• 🡩 rumen mass
• 🡩 papillae size
• microbial balance 🡢 fiber digesting + starch digesting organisms

high bacterial diversity through step 3

Question 11

VFA Absorption Buffering

Answer 11

buffer from rumen epithelium
organic acid outflow

75-85% VFA 🡢 rumen

Buffer = saliva
- 120 mm/L HCO3-
- dairy cattle 🡢 ~250 L/day
- feedlot 🡢 ~120 L/day
- neutralize~50% acid produced

Question 12

Rumination Time

Answer 12

🡩 ruminating 🡢 🡩 rumen pH
🡩 NDF/peNDF 🡢 🡩 ruminating
NDF + peNDF affect DMI

Question 13

CHO Source

Answer 13

🡩 NFC / starch 🡢 🡣 rumen pH

rate of degradation is important
- grain processing = rate + extent of digestion