Lecture 5: Bovine Andrology (Risco) Flashcards
Reproductively sound bull can:
detect fertile cow, breed her, and deposit fertile semen in anterior vagina
requirements for reproductively sound bull**
- physically sound and in good health
- have functional repro system
- have strong libido and fertile spermatozoa
- free of venereal diseases
what percent of dairy herd in U.S. use natural service?
20% (majority use combo of natural service and AI)
Most common sites of repro tract lesions/problems in bull
Scrotum (i.e. scrotal lesions affect thermoreg, quality of sperm)
Testicle (ie. orchitis)
Epididymitis
Accessory sex glands (i.e. seminal vesicle prone to seminal vesiculitis)
Penis (i.e. fibropapilloma, penile hematoma)
Prepuce (i.e. prolapse)
minimum recommended normal morphology %
70%
minimum recommended normal motility %
30% or “fair”
ideal bull:non-pregnant cow ratio in pasture breeding***
1:25
how long is breeding season in beef cattle?
~90 days
when should bulls be bought? age, etc?
- virgin bulls
- at least 60 days before breeding season
- at least 15 mo. of age
- temporarily quarantine
- allow to adjust to ration
breeding soundness evaluation includes:
PE exam of repro tract venereal dz testing libido testing? *a production tool*
BSE can increase pregnancy percentage by how much?
5-10%
BSE consists of:
ID and history (of o and bull)
PE
repro exam
collection and exam of semen
what should be included in BSE PE?
structural soundness BCS eyes feet/legs wounds, physical defects generalized dz rectal exam of internal genitalia external genitalia
internal genitlia rectally palpated on BSE PE:
prostate seminal vesicles ampulla inguinal rings *assess for size, shape, consistency*
external genitlia palpated on BSE PE:
scrotum, testes
spermatic cord, epididymides
penis/prepuce (sheath)
Know which animal has which sex organs***
- all males have prostate gland
- know which have seminal vesicles: bulls,…
accessory sex glands rectally palpated on BSE PE:
seminal vesicles
ampulla
prostate
bulbourethral glands
T/F: bull rarely suffers from any problems in the prostate gland
T (unlike dogs)
only frequently diagnosed disease of the bovine accessory sex glands
seminal vesiculitis
how is seminal vesiculitis diagnosed?
per rectum and by precipitate and cells in semen.
how is seminal vesiculitis likely spread?
hematogenously (i.e. actinobacillus)
abnormalities of the penis and prepuce
- neoplasia
- persistent frenulum
- prolapsed prepuce
- hematoma
- skin separation
- laceration
fibropapilloma
papilloma common on young bull penises
- most mild cases clear after excision
- no good vax available
- NOT a venereal disease
tx for penile hematoma
3-4 mo. rest; may need to be surgically corrected
-often followed by prolapse of prepuce
prolapsed prepuce
- most common in bos indicus breeds
- injury to preputial tissue with edema
- sequel to hematoma of penis
- can be congenital preputial abnormality
tx: sling, abx, 2-5 mo. rest, circumcision procedure
the most easily reproducible measurement for testicular mass (parenchyma) in the bull***
scrotal circumference
scrotal circumference highly correlates to:***
testicular size, sperm production
testicular mass reflects:***
parenchymal mass
benefits to beef herd in using bulls with large scrotal circumference
- earlier puberty in daughters and sons
- reduced probability that bulls suffering from testicular hypoplasia or degeneration will be mixed with the breeding herd
Exam Q: given 17 mo. old bull with scrotal circumference of 29 cm, fail or pass BSE?***
FAIL
bulls 15-18 mo. should have what scrotal circumference?
31-32cm
bulls 18-24 mo. should have what scrotal circumference?
32-34cm
in litter-bearing animals, sires selected for testicular growth produce daughters with:
more active ovaries
How does electronic probe work?
pathway involves sacral parasympathetic n. that includes internal pudendal n.
*dairy bulls do NOT respond well to this method!
How is semen evaluated?
Motility: gross, individual
Morphology: % normal/1ary abnormalities/2ary abnormalities, other cells (WBC, RBC,etc.)
min. motility threshold***
“fair”: generalized oscillation (30%***)
minimum recommended threshold for normal sperm morphology***
70%
primary abnormalities mostly related to problems in:
seminiferous tubules
2ary abnormalities most related to problems in:
epididymis and vas deferens
3 classifications of breeding potential
satisfactory
unsatisfactory
deferred
“satisfactory” breeding potential
- meets or surpasses the minimum thresholds for scrotal circumference, sperm motility, morph.
- does not show genetic, infectious, or other problems or faults which could compromise breeding or fertility
“unsatisfactory” breeding potential
- below one or more thresholds AND highly likely to ever improve!
- and/or shows genetic faults or irrevocable physical problems (including infectious dz) which would compromise breeding or fertility (i.e. lameness, pink eye)
“deferred” breeding potential
- bulls that don’t fit into above categories and may benefit from re-test
- bulls substandard but have capability to improve (i.e. very young bulls with low BCS)
most common reason for deferring a bull**
heat stress
- increases the number of abnormal sperm (usually 2ary) and dec. motility
- cold stress can have same effect up north
