Unit 4 - Pre-calving Management Flashcards
What are the 2 points of focus in pre-calving management?
1) nutrition and health of breeding females
2) AI and natural-service sire selection
What are the 5 key tasks in pre-calving management?
-reformation of diets to keep pace with fetal growth
-Vaccination against calf scours, if warranted
- preparation of and movement to calving areas
- Gathering calving supplies
-Selection of herd sites
What are the major functions of pre-calving management?
1) support of retained breeding females
2) health maintenance
3) preparation for calving
4) sire selection
How much fetal growth takes places during the final 60 days of gestation?
60-80%
Compared to a non-pregnant animal of the same weight, how much more nutrient requirement is there for a cow in gestation?
1.75 times greater
What can failure to react to diet change needs, in the final 60 days of pregnancy, lead to?
-weak labor
-increased dystocia
- extended post-partum interval
-impaired milk production
-reduced weaning weight
Define “Scours”
Is a term for calfhood diarrhea that occurs chiefly between 3 and 16 days of age.
HIGHLY CONTAGIOUS
What causes scours and what are the symptoms?
Cause: bacteria, viruses, protozoal parasites
Symptoms: rapid dehydration, death, and impaired performance
What can producers do to prevent scours?
-avoid crowding
-avoid commingling neonates and older calves during calving season
-vaccinate at 6-8 weeks pre-calving
-calves must consume adequate colostrum
What is the greatest danger to the health of a neonate calf born on pasture?
A herd mate that is greater than or equal to 2 weeks old
When should you move pregnant cows away from lactating cows with calves?
15 day intervals during the calving season
What are the benefits of replacing old bulls with young bulls?
-Maximize the rate of genetic improvement
-minimizes inbreeding
How much of genetic changes in most cow-calf herds do bulls provide?
90%
How many calves per year does bull management affect?
15-40 calves/yr.
If heifers are retained, how long will bulls influence the herd genetics?
Greater or equal to 10 years
How much are bull purchase prices?
$3,500 to $7,500
How much is the annual maintenance cost for bulls?
$1,000 to $1800
What is a bulls service life expectancy?
3-5 years
What is the serving capacity per breeding season for each bull?
About 25 cows on average
When selecting a sire what are their genetic values estimated by?
1) phenotype
2) individual performance (growth and scrotal performance)
What is “Expected Progeny Difference (EPD)”?
Provide estimates of genetic value of an animal as a parent in relation to other animals of the same breed
What is “EPD Accuracy”?
Estimated precision of an EPD value of 0.00 to 1.00
What are the 5 steps when selecting herd sites?
1) Assessment of herd records
2) Defining operational needs
3) Recognize genetic tradeoffs and environmental limitation
4) define operational philosophies
5) make your choices wisely
When assessing herd records what 3 characteristics should you look for?
1) reproductive success rates
2) weaning and yearling body weights
3) carcass merit
What makes up defining operational needs?
-bulls with strong maternal traits for use on heifers
-bulls with strong maternal traits for use on cows
-bulls with strong terminal traits for use on cows
What is the rate of genetic change?
1/n (n=number of traits being simultaneously selected)
We should recognize that most traits associated with what 3 traits tend to respond slowly to selection?
-fertility
-health
-longevity
Define “Maternal System”
Cow size and milk production are matched with feed resources, bulls of moderate biological type are selected and replacement heifers will have similar attributes to mature cows
Define “Terminal-Sire System”
Cows are mated to large, high carcass merit bulls, all calves are sol, and replacement heifers are purchased
Define “Combination System”
-replacement heifers are produced by mating bulls with maternally-desirable traits to young cows and heifers
-Cows greater than 4 yrs. Old are mated to terminal sites and all calves are sold
What is heterosis?
cross bred cows can make measurable improvement in genetic traits such as fertility, longevity, and health in comparison to their parents.
Define “Purebred System”
Supply single-breed or composite-breed bulls and heifers as seedstock for commercial cow-calf production
Define “Crossbred System”
Leverage hybrid vigor (heterosis) for added production efficiency.
What are the different levels of heterosis expression?
- low expression (0-5%) with carcass traits and mature size
-moderate expression (5-10%) with growth, WW, YW, and milk
-high expression (10-30%) with fertility, health, and longevity
