reproductive management of beef cows Flashcards
what do beef cows play an important role in
converting forage into high quality protein
what is key to the biological and economic sustainability
reproductive efficiency
what does achieving reproductive targets underpin
system efficiency and profitability
Key reproductive targets for beef cow
herds
Calving interval
365 days calving interval
what % of cows are cull annually as barren
<5%
what % of cows calving to wean a calf
> 95%
what % of cows should be calved in the first 42 days to have a compact calving
80%
what is the replacement rates for beef cow herds
16-18%
what age are heifers when they first calve
24 months old
what is the target calving interval
but
what is irish herds calving interval and how much does this cost
target: 365 days
irish herds: 403 days
costs €2.20/cow/day
what is the target calves/cow/yr
but
what is irish herds calves/cow/yr and how much does this cos
target: 1.0
irish herds: 0.8
cost: €170/cow
what is the target age of calving
but
what is irish herds age of calving and how much does this cos
target: 24 motnhs
irish herds: 15% of heifers 32.5 months
cost:€1.65/heifers/day
what is the national replacement rate% compared to the research %
national 14%
research 16%
what is the national calving rate% compared to the research %
national: 81%
research: 95%
what are the main factors of inefficiency
- prolonged calving season
- uneven calf crop
- low use of AI
- no defined planto produce replacement heifers
what are the two strategies to improve cost efficiency
- increase output to dilute cow costs
- reduce costs incurred by the suckler cow
how do you increase output to dilute cow costs
- optimal herd fertility targeted
- calf growth rates
- high calf quality are the principal factors of importance
what is the profitability on irish suckler farms driven by
striking the correct balance between
maximising the output per cow while at the same time controlling costs per cow
factors impacting reproductive performances of a suckler cow diagram
slide 9
factors affecting reproductive efficiency (3)
- age at puberty
- post partum interval
- conception rate
how much does ICBF indicate that each day is worth
€2.20
Two main factors that affect the post partum anoestrus interval
are:
- Maternal offspring bonding
- Nutrition (body condition score and plane of nutrition)
how many days / cycles have you to get a cow back in calf
50 days
2-3 cycles
how long is gestation
288 days
what does PPI stand for
post partum interval
what is the PPI of a dairy cow
mean = 26 days
(15-50 days)
what is the PPI of beef cows
mean = 55 days
(25-180 days)
are beef cows slow/.fast to come in heat after calving
slow
beef cows oestrous cycle
average 60 days
range 20-120 days
length of dairy cows oestrus cycle
average 30 days
range 20-50 days
how long is post partum anoestrus
14-170 days
Ovulation or (ii) Atresia of 1st Post-Partum DF diagrams
slide 16
postpartum cyclicity in suckled cows
slide 17
by what day does one large follicle develop in all cows
6-8 days postpartum.
how many outcomes has the follicle affecting days to 1st ovulation
3 outcome
what are the 3 possible outcomes
Incidence Days of ovulation
ovulation 5% 20
regression 93% 65
cystic 2% 60
Average 55-60
interval between first and second ovulation in beef cows
short (<18 days)
short (<18 days) - 85%
interval between first and second ovulation in beef cows
normal (18-24 days)
normal (18-24 days) 13%
interval between first and second ovulation in beef cows
extended (<24 days)
extended (<24 days) - 2%
what is anoestrus
Due to Failure of Recurrent
Dominant Follicles to Ovulate
POSTPARTUM ANOESTRUS IN
BEEF COWS
Not due to delayed resumption or lack of follicle growth
As a consequence of
Sequestration of LH stores in the gonadotrophs in the anterior pituitary due to inadequate pulses of GnRH
Factors affecting the PPI
- Maternal-Offspring Bonding
–> number one factor that affects the length pf PPI
-Nutrition
–>Pre-partum - more important
–>Post-partum - Parity
-Season - Bull effect
-Interactions
Effect of Suckling Treatment on PPI
(Days)
free access:
restricted:
free access: 62 days
restricted: 42 days
LH pulsatility during the oestrous cycle
- the oestrus cycle of a cows
- luteal - high progesterone levels after ovulation
- early follicular phase
- Don’t have sufficient LH pulse – 1 LH pulse per hour is what is needed to ovulate
- If u have a mature follicle and have a sufficient LH pulses to ovulate.
- Late follicular phase spike – LH spike and with that you get estradial spike as well.
Explain parity - the fact affecting PPI
o Heifers have much longer PPI than that of cows as they have a much larger energy requirement to meet their growth rate
o First energy sink of an animal
- Maintenance 60-65%
- Production
* Dairy cow: milk
- Growth - heifer has greater growth potential than a cow but DM intake is less
- Reproduction
* Resumption of cyclicity
* Heifer as to be managed differently than cows
- Heifer takes 15-16 days longer to come into heat
what affect does the bull effect have on PPI
o Present of bull/teaser can bring them forward by 10-12 days
Serum LH at 29 and 34 days postpartum in
beef cows
- 34 days is extremely early
- Restricted adjacent
- Restrict isolation
on what day does breaking maternal off spring bonding commence
Commence calf separation at Day 30
what % of cows ovulate by day 36 and what sort of a ovulation is it
85-90% of cows ovulate by day 36
it is a silent ovulation
what % and with how many days do cows exhibit fertile heat
95% of ovulated cows exhibit fertile heat with 8-12 day (short cycle)
what% of cows exhibit fertile oestrus within how many days??
5% of ovulated cows exhibit fertile oestrus within 17-22 days
(normal cycle)
what % of cows fail to ovulate in response to calf separation
10-15%
Deep – “Nutritional” anoestrus
- Thin cows at calving in particular
- No matter what you do you are going to have a delayed PPI
what % of cows exhibited fertile heat by Day __
80% of cows exhibited fertile heat by Day 45.
what does body condition score describes
fat reserves
what point scale does UK and USA use
5 point scale (UK)
9 point scale (USA)
key points BCS to ensure reproductive efficiency of animal is met (3)
- Calving
- Breeding
- weaning
what is BCS at calving an indirect measure of
pre partum nutrition status
effect of post calving nutrition on PPI
low plane of nutrition after calving: 55 days
High plane of nutrition after calving: 50 days
effect of post calving nutrition on PPI
- Post partum nutrition has not the same impact of reducing the PPI of a beef cow
- BCS at calving is directly linked to Pre partum nutrition
- Post partum nutrition is very hard to correct
Suckling- LH - Insulin and Ovulation
Relationships
slide 35
Factors Affecting Probability of
Conception
- accuracy of heat detection
- accuracy of insemination
- semen quality factors
- female factors
what are the factors for failure to detect heat
cow factors -10%
management factors - 90%
what is a primary sign of heat
mounting another cow
Primary Sign of Heat - slide 40
- key challenge in conception a farmer has to decide
o The ovulatory event of cow
o And semen insemination - When animal is being mounted: how long will ovulation take place after?
o 28-31 hours in dairy and beef after sign of first heat
o Semen needs to go through o process called capacitation -
o Inseminate 12-18 hours after 1st sign of heat
AM/PM rule
Distribution of heat onset throughout day
- 6-9 in morning and 6-9 in evening
o Most efficient time
when is the most effective timing for conception rate %
12-18 hours (interval from detected heat to AI)
- 60% conception rate
Factors Affecting the Expression of Heat (2)
1.Size of the Sexually
Active Group
2.Under foot surface
Conditions
what effect has the underfoot surface on the number mount received during heat
- significant decrease in mounts when cows are on slats - only 14 mounts
- Oestrus activity could be reduced by 50% with cows on slats
- Cows on slats are slow in terms are mounting activity
o 60% are silent heats - Introduce teaser bulls on slats which will detect heat
- highest number of mounts when cows are out on pasture
Aids to improve heat detection rate(6)
- Tail paint/ Chalk
- Heat Mount detectors
- Scratch Cards
- Restricted suckling
- Teaser Bull
- Synchronisation
when using a bull (natural service) what % is infertile and sub fertile
3-5% infertile
10-25% sub fertile
- Young bulls die to environmental change/stress
- Change in nutritional diets – stress
Infertility
what way are most suckler cows bred
using natural service (>80%)
what effect has the presence of a bull
expect to advance period to 1st heat
and pregnancy by up to 14 days.
if heat detection is accurate and AI
timed and carried out correctly what is the conception rate
conception rate is similar following
either AI or natural service
what are the conception rates to AI in dairy cows vs Beef cows
dairy cows: 52
beef cows: 65
what are the problems in using AI for beef cows (4)
- Not as easily detectable in heat
–> maternal/calf bond - More difficult to collect for AI
- Often located in outfarms with less
facilities available - Many part-time farmers
what are the advantages of AI (8)
- Access to proven bulls
–> Information available on many traits
–> Use different breeds - Knowledge on calving difficulty - use easier calving bulls on heifers
- Match bull to cow
- Breed replacement heifers
–>maternally tested sires - Eliminates potential hazard of bull
- Eliminates specialised housing
requirements - Avoids risk of temporary/permanent
infertility that frequently occurs with
natural service bulls - Eliminates the risk of introducing or
spreading disease
what is a suboptimal use of AI in beef cow
oestrous synchronisation
what is seen as major obstacles to AI use
- labour
- heat dection
what is gaining interest in South america
use of synchronisation and fixed time AI
what are three primary goals for synchronizing oestrus and
ovulation in beef herds:
- Develop reliable protocols that rely solely on TAI
- Develop systems that require a maximum of 3 animal
handlings - Ensure that systems are successful in anoestrous or
peri-pubertal and cyclic females at any stage of the
oestrous cycle.
what is a major contributor to poor reproductive efficiency of beef cow herds
anoestrus
what is the exposure to progesterone
is a prerequisite to first
postpartum behavioural oestrus in most cows
what does the duration of luteal phase after first PP ovulation often shorter than normal result in
an infertile shorter cycle
are GnRH/PG based strategies alone are not adequate for anoestrous beef cows
no
what are Two Main Base Protocols for Beef Cows
- 7-day CO-Synch + PRID/CIDR:
- 5-day CO-Synch + PRID/CIDR:
understanding –> 5-day CO-Synch + PRID/CIDR:
GnRH administered at
PRID/CIDR insertion, followed 5 d later with PRID/CIDR removal and
administration of 2 injections of PG; the first at PRID/CIDR removal
and second 12 h later. TAI is performed 72 h after first PG and CIDR
removal concurrent with a second GnRH injection
understanding –> 7-day CO-Synch + PRID/CIDR:
GnRH administered at
PRID/CIDR insertion followed 7 d later with PG at PRID/CIDR
removal. Inseminate 66-72 h after PG and CIDR removal
coincident with GnRH administration.
presence/ absence of CL on pregnancy rate
NO CL% WITH CL%
No GnRH 47.4% 54.7%
GnRH 49.7% 58.1%
GnRH+ 56.6% 57.2%
eCG
what are the Effects of concurrent nutrition on embryo survival rate in heifers
- animals around breeding on a consistent plane of nutrition
- Embryo survival from cows going from a high to low plane of nutrition
- When breeding cows you need to have a consistent diet
o If cows are on a low plane of nutrition, will suffer with milk yield but the % of embryo survival will be the same
what happens when you delay the age of first calving from 24 to 36 months
it decreases net margin per ha by 50%
what is the average age of first calving in beef heifers in ireland
31.5 months
what % calve for the first time between 22-26 months
20%
definition of puberty in heifers
- Puberty is defined as the first ovulation followed by a luteal phase of normal duration
- The onset of sexual maturation
in the top 15% of herds, what % of heifers 1st calve at 24 months
50%
what are the major factors affecting age at puberty
- Breed
- Plane of nutrition
- Heterosis
- Bull effect ?
- Moderate Heritability
o Can improve through genetics
what factors affect onset of puberty (4)
- hormonal
- genetic
- environment
- nutritional
what does GnRH pulse generator central
Neuroendocrine Control of Puberty
onset of puberty
what goes initially negative E2 feedback turn into
Positive Surge release of GnRH
where does pre ovulatory surge of LH come from
the anterior pituitary
what do Different tissues and organs from the body send signals to the
hypothalamus indicating
the metabolic status of the animal
slide 82
at what age (months) has beef heifers reached what % of mature weight
60 to 65% of mature weight at 13.5-14 months
at what age (months) has beef heifers reached what % of first breeding
65 to 70% at time of first breeding (15 months)
at what age (months) has beef heifers reached what % of mature weight at calving
85-90% of mature weight at calving (24 months)
why is it important to ensure beef heifers reach theses weights (3)
- High proportion cycling regularly at start of breeding season
- Physically well developed at calving
- Early resumption of heat activity after calving
How are animals measured
DMI
* Bodyweight
* Blood sampling
* P4 - > 1ng/ml
* Body composition
* Muscle
* Fat
* Reproductive scanning
conception rate % at 1st and 3rd heat post puberty in beef heifers
1st heat - 57%
3rd heat - 78%
what is the effect of maternal nutrition on postnatal reproductive traits of heifer progeny(3)
- Dams offered 0.6 or 2 x
maintenance energy requirements
from -11 to 110 d of gestation - Ovarian antral follicle count lower
for heifers from nutrient restricted
dams - No effect on: - birthweight - postnatal growth - age or weight at puberty
what has the maternal nutrition on postnatal reproductive trats have no effect on
- birthweight
- postnatal growth
- age o0r weight at puberty
Important points on heifers (3)
- Have heifers well grown at 12 -13 months of age
- Restrict breeding to the first 6 weeks of the breeding season and use easy
calving bulls - Aim for a BCS of 3 at calving
important points on cows (3)
- Monitor BCS through last 1/3 of gestation & adjust feeding accordingly
- Calve down cows in moderate to good BCS
- Restricted suckling can advance the onset of cyclicity
important points on breeding management
- Avoid fluctuations in feed supply during the breeding season
- Heat detection critical when using AI
- Vigilance for bull fertility particularly with young bulls
