Improving Beef Cattle Pregnancy Rates Flashcards
What are the conception rate goals in beef operations?
AI rate: 60-65%
Bull rate: 60-65%
Season long rate: 90%+
What must happen for cows to become pregnant early in the breeding season?
- Cow must be cycling at the beginning
- Cow must be fertile
- Bull must be fertile
T/F: In most cases failure of beef cows to cycle at the beginning of the season is due to an underlying disease
False- usually not due to disease
What are Wiltbank’s factors affecting return to cycling?
- Time post-partum
- Body condition score at calving
- Age of cow
- Suckling (impedes return to cycling)
- Bull exposure
- Exogenous hormones
What are Wiltbank’s factors affecting fertility?
- Time post partum
- Weight gain/loss during breeding period (negative vs positive energy balance)
- Heat stress associated with fescue (summer slump- early embryonic loss due to increased body temps)
What is the only was to reliably assure that cows have adequate time postpartum for cycling to begin at the beginning of the breeding season?
Must enforce a short breeding/calving season
-many often erroneously assume that a longer breeding season will give cows more time to get pregnant
-cows which conceive late in this season will be at a decided disadvantage for conception in next years breeding season
How long should the breeding/calving season be?
65-70 days (3 cycles)
What is a wet 2 year old and what are the main issues associated with them? How can you address these issues?
First calf heifer that is lactating
- they have 3 jobs: finishing growing, raising their calf and getting bred back
To address the problem: get them bred for the first time earlier in the season to have them calf before the cows (to give them more days postpartum)
- also allows for more eyes on them as they tend to have more problems with parturition
Why should you not BCS cows at calving?
Varies a lot from right before she gives birth to right after- not very accurate
- better to do at breeding
What is the ideal BCS at breeding?
5-6 at the start of the breeding season
- goal is to maintain BCS through season or lose <1 BCS
What should be your goal of how many days to feed hay in VA?
100-120 days
- very hard to get lower than this without having a very low stocking density
- if days are much more than this, consider lowering the stocking density
- depends on climate of the year in question/quality of the grass
What are the 3 things that result in very rough winters for cows?
No fall grazing, long cold winter, poor quality hay
- wind up with infertility problems and starving to death
What should be the goals for grass hay in terms of crude protein? What about NDF?
Protein >10%
NDF should be as low as possible=better quality
- high NDF will lead to decreased consumption as well as poor nutrition
What is the difference between ADF and NDF
ADF contains cellulose and lignin
NDF includes cellulose, hemicellulose and lignin
Why are protein blocks not recommended in most cases?
Expensive way to provide something that the cows are not deficient in
- they need ENERGY
What is the ideal bull:cow ratio?
1:25-40
For yearling bulls it is 1 cow per month of age
What are the limits of BSEs?
-They do not assess poor libido
-doesnt account for bull problems in season (injury, dynamic changes in sperm quality)
-some failures occur without a known cause
What is the farmers role in productive breeding?
-At turnout, watch to make sure bulls go and actually breed cows
-watch for bull injuries
-watch for cows coming back into heat
-try to have multiple bull groups
-switch bulls between groups halfway through breeding season
What factors define bull fertility?
-Sperm cell output (directly proportional to scrotal circumference)
-percent normal sperm cells produced (normal morphology)
-motility or ability for forward progressive movement of sperm cells (maybe not as important as once thought)
-a normal male reproductive tract
-physical normality of bull, general health and structural soundness
-ability of bull to complete an insemination successfully or mating ability
-libido or sex drive
-social interactions between bulls (not a problem in large pastures)
-age of bull (young bulls sire the least calves)
-body condition score
What are the current recommendations for bull BCS prior to entering the breeding herd?
Bull should be a BCS of 5 at start of season
- over conditioning has possibility of decreasing season long pregnancy rates
