Lecture 22: Beef Nutrition 2 (Exam 2) Flashcards by Shelby Rainbolt

What does the lower critical temp (LCT) depend on

Hair coat
Weather conditions

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How does cold stress increase energy req

Energy requirements increase 1% for every degree below LCT in cold dry conditions & 2% in cold wet conditions

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Why are added factors included to adjust for environmental conditions

Internal insulation factors
Hide thickness
Heat production from feed

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How do forages help w/ heat production

They have a higher heat increment than grains so they increase heat production assoc w/ food consumption/metabolism

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What is the goal BCS score of beef cows @ the beginning of calving season

BCS of 5 - 7 @ the beginning of calving season & remain @ the same BCS through breeding season

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What can BCS affect

Repro performance (interval from calving to first heat)

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What is the relationship btw/ BCS & interval from calving to first heat

Shorter interval to first heat is seen w/ higher BCS

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How does Low BCS affect colostrum

Lower BCS = Lower quality colostrum = lower IgG levels in calves

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How does BCS affect pregnancy rates

High & low BCS conditions can lead to lower pregnancy rates
< 5 or 7 @ calving will impeded repro/preg

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Why should cows be grouped based on their BCS after calving

To be able to feed the groups based on their condition needed

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Why are BW changes not sufficient to eval condition in ruminants

Due to gut fill

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What % mature weight should heifers be @ breeding & @ calving

@ breeding: 65%
@ calving: 85%

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@ Least how much CP and NEg should heifers be getting

11% CP
36 - 42 Mcal NEg

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What is preconditioning

A management method that prepares calves for auction or the feedlot
Spreads out stressors that calves can experience (weaning, vax, transport, etc.)

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What do cow calf producers do for pre conditioning

Males are castrated
Vaccination
Get them acclimated to feed bunks
weaned for @ least 30 - 45 D

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What is a value added calf

Preconditioned
Quality assured (injection sites in front of the shoulder)
and verification of ID, age, & source

What are the energy needs to stocker cattle w/ a ADG above 0.5 lbs/d

Need additional dietary energy when fed low quality hay or during winter/late summer feedings (supplement w/ high quality forages, by products, etc)

What can be deficient in stocker cattle when using a low quality hay

Protein

What usually needs to be supplemented in growing cattle

Protein (mainly UIP)

How much CP should stocker cattle diets have

@ least 12 - 16%

What % CP do supplements have

25 - 40% CP

Why does urea do well w/ high energy diets but not w/ high forage diets

B/c forage diets are digested too slowly for urea to be utilized

What are the risk of high grain diets in feeding program/transition diets

Acidosis
Laminitis
Liver abscesses

Describe the diets of feeding programs/transition diets

9 - 14% CP
Need to supplement Ca but probs not P
Need forage in diet for proper rumen function
Source of grain depends on the feedlot location

What are the concerns of the transition period for adapting feedlot steers

* Maintaining DMI * Adjusting the microbes to new substrates (grain)

What should the steers initial grain consumption be

0.5 to 1% of body weight

What is one approach of adapting feedlot steers to grain

* Start w/ 60% forage w/ 40% concentrate * Final diet of 90% concentrate & 10% forage

What are some nutritional probs in beef cattle

* Grass tetany * Nitrate Poisoning * Mycotoxins * Urinary calculi * Sulfur toxicity * Grain overload/ acidosis * Bloat (frothy & free gas)

Describe gas tetany (How its caused, how to prevent, and symptoms)

* Cause: low Mg & spring grass is high in K+ * Prevent: Have Mg block * Symptoms: Muscle twitches, incoordination, & collapse

Describe nitrate poisoning & the symptoms that it causes

* Nitrates are reduced to ammonia in the rumen w/ nitrite as an intermediate (this leads to methemoglobin * Symptoms: Weak heartbeat, staggering, muscle tremors, hypoxia

Describe mycotoxins (what causes it, whose most sensitive, & symptoms it causes)

* Caused by corn seeds & corn silage * ~38 mycotoxins * Calves are most sensitive * Symptoms: decrease in DMI & growth

What causes urinary calculi

Grains are high in phosphorus

What is a major consideration when using distiller grains & dry distiller grains

* Sulfur toxicity * They have variable sulfur contents * Sulfur can be very high in feeds from some ethanol plants * Sulfur toxicity is a risk factor for polioencephalomalacia & sub acute rumen acidosis

Describe polioencephalomalacia

* Caused by feeding distiller's grains to beef steers * Can take weeks to dev * Sulfur is reduced to sulfide & hydrogen sulfide gas accumulates & interferes w/ cell metabolism & affects the CNS (blindness, recumbent, & seizures)

What are hormonal implants used for

Used during growth & finishing to increase ADG by 15 - 20%

What is MGA (melengestrol acetate) used for

* For feedlot heifers * Suppresses estrus to maintain DMI

What is optaflexx (ractopamine) used for

A beta agonist used as a repartitioning agent for more muscle instead of fat

Describe Ionophore antibiotics

* Feed additives that selectively target some rumen bacteria * Direct metabolism towards deposition of muscle instead of fat * Improves feed efficiency & decreases incidence of acidosis