Exam 2: Lecture 22 - Beef nutrition 2 Flashcards
what must be accounted for when looking at effective temps
determining when the energy needs of cattle increases
what does lower critical temp depend on
hair coat and weather conditions
how much does cold stress increase energy requirements by
1% for every degree below LCT in cold dry conditions and 2% for cold wet conditions
what is important to remember about changing energy requirements in cattle
do NOT make rapid or dramatic diet changes but may need to increase hay and grain
what are the added factors for environmental adjustments in NRC
- internal insulation factors
- hide thickness
- heat production from feed
T/F: forages have higher heat increment than grains
true!!
T/F: grains are more energy dense and increase heat production in animals on poor quality forage diets
very true
what is the beef cow BCS scale
1-9
what is the ideal BCS of a beef cow
6
what does a BCS measure for beef cattle
sub-cutaneous fat reserves
what should the BCS of beef cows be at beginning of calving and remain through breeding
BCS of 5-7
how do BCS affect repro performance
shorter interval to first heat with higher BCS which is a GOOD thing
T/F: cows with higher BCS produce lower quality colostrum
FALSE! lower BCS = lower colostrum
why are body weight changes not sufficient to eval condition in ruminants?
bc ruminants have a HUGE GI tract so you can have variation of gut fill
A BCS of less than __1__ and above ___2_ at calving will impede repro/pregnancy
- bcs of less than 5
- above 7
what is the ideal BCS of first-calf heifers
BCS of 6….. they are still growing so a 7 will be tooooo fat
T/F: after calving it is ideal to group cows based on BCS so you can feed each accordingly
true!!
heifers should be _1___% of mature weight at breeding and ____2__% of mature weight at calving
- 65%
- 85%
T/F: heifers should be fed separately from the rest of the herd
true!!
what is the minimum CP for a heifer
11% CP
what is a management method that prepares calves for auction or to enter feedlot
spread out stressors like weaning, vaccinations, transportations, unfamiliar enviros, dietary changes
what management things are carried out by cow-calf producers
- males castrated
- vaccinated
- feed bunk acclimated
- weaned for at least 30-45 days
what 5 things add value to a calf
- preconditioned
- quality assured (injection sites)
- individual ID
- source verified
- age verified
what is the ideal BCS for a beef cow at calving?
A. BCS of 3-5
B. BCS of 4-6
C. BCS of 5-7
D. BCS of 6-8
C. BCS of 5-7
what level of ADG do we need to add additional dietary energy when fed low quality hay or during winter/later summer
ADG above 0.5 lbs/d
T/F: depending on goals of ADG of 2-3 lbs/d, supplementation varies
true!
T/F: if low quality hay is used then they are probably protein deficient
true!!
you need at least ___% CP in forages to maintain health and growth of rumen microbes
8%
T/F: you dont need to supplement protein for growing cattle
false! You usually do, specifically UIP
what should the overall CP be in the diet for growing beef cattle
12-16% CP
why does urea do well with high energy diets but not high forage diets??
bc need energy that is readily avail for microbes to use and forage diets are digested tooo slowly for urea to be used
what are the risks of high grain diets
acidosis, laminitis, liver abscesses
what is needed in the diet for proper rumen function when entering the feedlot
need forage!!
what is the transition period concerns when adapting feedlot steers to grain for finishing
need to maintain DMI and adjust rumen microbes to new substrates
what is the initial grain consumption of feedlot steers going to finishing
0.5 to 1% of body weight
what is one approach to adapting feedlot steers to grain for finishing
- start with 60% forage, 40% concentrate
- final diet of 90% concentrate and 10% forage
what is the goal of the feedbunk for feedlot cattle
delivery of constant, nutritious, fresh ration in a manner that maximizes feed intake and minimizes waste/spoilage
what should the level of CP be in the overall diet of growing stocker cattle?
A. 5-8% CP
B. 9-12% CP
C. 12-16% CP
D. 15-19% CP
C. 12-16% CP because it supports growth
what is grass tetany
low Mg, spring grass that is high in K
see muscle twitches, incoordination, collapse, and death if no treatment
how do we help with grass tetany
provide Mg blocks and potentially give IV Mg if needed
what is nitrate poisoning
- fertilized pastures have high nitrate
- nitrates in rumen reduced to NH3 which produces nitrite as an intermediate
- nitrite leads to methemoglobin (when there is no O2 carriage)
what are the clinical signs of nitrate poisoning
weak pulse/heart beat, staggering, muscle tremors, tissue hypoxemia, sudden death
when can we see mycotoxins
various corn feeds, corn silage
what are mycotoxins
molds that produce toxins (about 38 diff kinds)
T/F: Calves are the most sensitive to mycotoxins and have a decrease in DMI and growth
TRUE
what does urinary calculi result from and how can we help with it
results from grains that have high P
supplement with Ca to hopefully avoid
what does sulfur toxicity come from
usually distillers grains and dry distillers grains due to a variable S content
what is sulfur toxicity a risk factor for
polioencephalomalacia
what is polioencehaplomalacia
it takes weeks to develop and the gas interferes with cell metabolism and CNS is affected leading to blindness, recumbency, and seizures
what are the estrogenic hormonal implants
estradiol, progesterone, zeranol
what are the androgenic hormonal implants and why are they used
testosterone, trenbolone acetate
common to use during growth/finishing and increases ADG bu 15-20%
what is MGA (melengestrol acetate)
a progesterone analog that suppresses estrous to maintain DMI because estrous makes them eat less
what is optaflexx (ractopamine)
a repartitioning agent that increases muscle instead of fat
it is a beta-agonist that is used in the last 24-48 days of finishing
why is optaflexx (ractopamine) controversal
because of the high death associated with it
what is coccidostats
used in young cattle and feedlot cattle to control naturally occurring coccidiosis and improve ADG
what are ionophore antibiotics
feed additives that selectively target some rumen bacteria
what are examples of ionophore antibiotics
monensin (rumensin), iasalocid (bovatec)
what are the benefits of ionophore antibiotics
- direct metabolism towards deposition of muscle instead of fat
- improve feed conversion by 5-10%
- improve feed efficiency and decrease incidence of acidosis
What must happen for us to use broad spectrum abx in cattle
must be used under vet supervision!!
What is effective temp based on
air temp, moisture, air speed
