Exam 3 Flashcards
job description for beef cow
she must breed, calve, milk sufficiently to feed her calf, breed back to calve in 365 days, produce claves that are in demand, do all this on your type of forage, pay for all her groceries and part of yours.
which breed is best? which cow size is best?
No one correct answer, environment is important. ln general, if quantity and quality of feed is abundant then large cow size with high milk potential is possible. If sparse nutritional conditions exist, then moderate size with lower milk production probably best.
consumer requirements
high lean to fat ratio. select to choice quality grade.
packer requirements
650-850 lb carcasses = 1000 -1350 lb live. steer = choice grade @ ~80% of avg. mature wt of sire and dam. Also steer = choice grade @ ~same wt as dam when sire and dam are about same frame size. (A cow with a body condition score of 5 is equivalent to her steer calf at choice grade).
feeder requirements
wants animal that grades low Choice at 1100-1200 lb. highest proce with yield grade 2-3 choice. go over 4 and you get docked ~$15-20/cwt.
cow-calf producer requirements
produce a heavy calf from a small cow. cost correlated to weight. ~70% choice. (BF = .4-.5 in).
Back fat
.4-.5 = ~70% choice. measure BF between 12-13 rib and ~5 in from top.
fat deposition
internal, subcutaneous, intermuscular, and intramuscular (marbling).
comparing large frame cattle to smaller framed cattle
At any given wt, large framed cattle gain faster (more on linear curve). At a given wt, nutrient requirements of growing/finishing cattle are greater for large framed cattle. when fed to a constant wt, large framed cattle will gain faster and have better F/G. When fed to a constant carcass composition, (.4-.5” BF) large framed cattle usually are less efficient, will have only a slight advantage in ADG, and prob wont have any advantage in days on feed (my even take 2-3 week longer). When fed to same carcass comp, stockered yearlings will be 100-200 lb heavier than calves placed immediately in feedlot.
nutrient requirements
NEm directly related to wt: NEm = .077W^.75. NEg related to sex, frame size, mature size (calf, yearling, compensating), body fatness. CP relationships similar to NEg.
NEm equation
Burn maintenance energy. Heat dissapation is proportional to the surface area of your body, and the weight in kilogram raised to the .75 is an equivalent value of surface area.
when choosing a breed, consider
Select something you like. cost and availability. Maternal traits this breed offers in a crossbreeding program (milk, bw, age at puberty, ability to breed back). Are they marketable in your area? Adaptable to climate they will live in (maintain body condition, quanity and quality of feed, how much suppl feed needed). Disposition. Body size and milk prod important factors that help determine feed requirements for cow and weaning weight of calf.
energy required increases
As milk production increases. And as cow size increases. increase wt 100 lb = increase maintenance 6-8%.
bigger cows require better management
greater maintenance requirement. usually are less fertile (prob related to nutrition). frequently have more calving difficulties.
greater milk production is not always desirable
Most beef cows avg. 10-12 lb milk/day, avg conversion = 1lb calf gain/10 lb. milk. Conversion rate by calf decreases as milk consumption increases. one study: net $ return favored ~14 lb milk/day (this will wean !550 lb calf with adequate forage). Too much milk is correlated with poor reproduction, calves often contract milk scours (be dehydrated), and cows predisposed to mastitis.
no way to recommend ideal cow type
Producer must determine what is the heaviest milking cow type that can consistently rebreed with the most likely feed resources, grown and purchased, that can be provided. Depends on availbale feed resources, cost of producing feed, amount of suppl feed purchased, and expected ww and calf prices.
small cows can wean heavier calves
Use moderate size cow (900-1100 lb 3+ tp 5 frame). Select dams for high maternal performance. Select sires for growth and carcass traits. Increases growth = it is more efficient to have larger sires than larger cows (but this will usually increase dystocia). can wean 500-600 lb calves with excellent feedlot and carcass performance. Need source for replacement heifers
compared to straightbred, crossbreds have greater return on investment.
Heterosis increases lb calf weaned/cow exposed ~20%. 65-75% of this increase is due to increased fertility. 25-35% of this increase is due to increased growth rate of calf and increased milk from cow (= increase WW). Growth weight and milk production have high heritability and low heterosis.
British breeds (compared to exotics)
Mature and fatten at lighter marketweights (1200-1350 lb). grow slower, smaller mature size. less muscular. more fertile. fewer calving difficulties. live and reproduce longer. used as maternal breeds in crossbreeding programs.
continental exotoc breeds (compared to british breeds)
large mature size (1350-1400 lb at market weight). later maturing. heavier muscled, this higher yielding carcasses. less fertile. increased calving problems. less marbling, thus lower quality grades. normally used as sire breeds in crossbreeding. some of the more fertile, moderately sized exotics are used as both sire and dam breeds (Gelbvieh and Saler).
Brahman and Brahman derived breeds
heat tolerance. have sweat glands. thinner hide. increased sa. parasite tolerance. crosses with british and exotics produce high heterosis. Undesirable characteristics are nervous disposition, pendulous sheath, meat is tough (>25% brahman, partly bc they cant be slaughtered w/out agitation or excitement, more connective tissue in the muscle of brahman cattle). not adaptable to cold climates.
importance of sire selection
one of the most important decisions producer will make. decisions havbe long term impact: calving ease, maternal ability, growth, carcass merit (minor importance bc you dont get bonus for marbling).
Sire selection: producer must…
Set goals. accurately assess current and desired genetics (breed makeup, production level of herd (need good records), determine frame size and weight (650-800 lb carcass)). assess management (forage base and need for stored feeds). determine marketing goals. Understand EPDs and how to use them. Keep up with selection technology.
most genetic progress is through the sire.
limited opportunity for genetic progress through females (low selection intensity - large portion of potential replacements must be retained), logevity is important, genetic info for heifers is limited: EPDs have low accuracy. By contrast, amount of genetic info available for sires can be overwhelming. number of progeny from sires increases accuracy of info. last 3 sires impact 80-90% of genetic progress in a herd.
