Swine Flashcards
(99 cards)
when does farrowing occur with periodic farrowing?
twice yearly
how old is a finisher pig?
up to 6 months
how large are piglets when they are weaned?
12-15 lbs
what type of breeders are sows?
nonseasonal polyestrous
how prevalent is artificial insemination?
90% of USA swine farms
how long does pregnancy last?
113-115 days
do nursing sows experience lactation anestrus?
yes
what is the weaning to estrus interval?
4-6 days
how many oocytes do sows ovulate each estrus?
15-30 oocytes
do swine have follicular waves?
no
how large are follicles in estrus?
7-12 mm
what happens during the follicular phase?
number of small and medium follicles decreases: leave roughly 20 follicles 7-10 mm in diameter which will go on to ovulate
what can be seen when a sow is in estrus?
standing heat: reflex immobility
redness of vulva with production of thick/whitish mucus
how long does the estrous cycle last?
18-24 days
mean 21 days
how long does estrus last?
depends on presence of boar
40-60 hours
can vary <24 hours and >96 hours
what is estrus duration affected by?
intensity of boar contact during estrus detection
stress
parity
weaning to estrus interval
when does the corpus lutea reach their final diameter?
one week after ovulation
how long is development of the corpus luteum and production of progesterone independent from luteinizing hormone production?
10-12 days after ovulation
when does PGF2alpha cause luteolysis?
day 15
does the corpus luteum last for the entire pregnancy?
yes
why does lactational anestrus occur?
luteinizing hormone suppression
what is the degree of luteinizing hormone suppression related to?
suckling intensity
negative energy balance
stress
what is the common boar to sow ratio for group/pen mating?
1:8
when should you mate sows with hand mating/observed mating?
24-hour intervals