Bovine Repro6

Front 1

Why is it important to maitain accurate herd records and what should be in a minumum database

Back 1

• Improving reproductive performance in herds requires the maintenance of good records.
• Without good records it is difficult to diagnose problems and to accurately institute treatments or monitor responses to treatment. Inadvertant abortions or unnecessary treatments can also result from poor records.
• Minimum data base:
– Cow id, birth date, Sire, calving date, AI dates (including sire), preferably medical treatment record.

Front 2

What is the difference between anovulatory and ovulatory anoestrus

Back 2

Anoestrous refers to the failure of cows to enter oestrus or to be detected in oestrus
Two types:
– Anovulatory anoestrous – absence of oestrous behaviour is accompanied by failure to ovulate
• Ovaries are smaller compared to cows undergoing oestrous cycles.
• A CL is not present

– Ovulatory anoestrous – oestrous behaviour has not occurred or has not been detected but the animal has ovulated.

– 10 to 30% of cows that have not been detected in heat by the start of the breeding period may have a CL.

Hint 2

• Anoestrous is normal during the early post partum period. It becomes a problem if cows remain anoestrous when they are required to be bred.
• It is a major cause of reduced reproductive performance in beef and dairy herds as it delays the time from calving to conception.
• Anoestrous cows when treated with an oestrous synchronisation treatment also in general have reduced pregnancy rates compared with animals that are undergoing oestrous cycles at the time of
treatment.

Front 3

What is typical for the first post partum ovulation?

Back 3

The first postpartum ovulation is often associated with an absence of oestrous behavior and is often followed by a luteal phase of short duration (7 to 10 days)

Front 4

What is the duration of anoestrus

Back 4

Variable: 14 to 80+ days (depends how long exposed to risk
factors and BCS at calving
Some chronically undernourished cows may fail to ovulate for >1year
Most commonly 20 to 40 days
First calf heifers often have longer calving to first ovulation
intervals

Front 5

What is the prevalence of anoestrus in seasonal calving dairy herds?

Back 5

Percentage of a herd affected: variable between and within farms (why would it be variable?)
In seasonal calving dairy herds 15 to 30% of cows in a herd are often anoestrous at the time when mating is to commence

Front 6

What are possible causes for anoestrus?

Back 6

Ovarian quiescence
Behavioural anoestrus
Anoestrus caused by prolonged luteal function
Anoestrus caused by failure to detect oestrus

Front 7

What can cause ovarian quiescence?

Back 7

– Nutritional anoestrus/poor body condition/lack of energy and protein, declining body weight and condition
– Nutritional deficiency – deficiency of micronutrients eg P
– Nutritional excess prepartum - overfeeding
– Lactational anoestrus – negative energy balance associated with lactation can delay cyclicity
– Suckling – negative effect on cyclicity, can delay interval to firstovulation postpartum
– Disease – eg gastrointestinal parasitism, lameness, uterine inflammatory disease, severe illness
– Pathology: Ovarian tumours
– Cystic ovarian disease
– Age: prepubertal or have not reached adequate target weight for breeding. First calf heifers often have delayed onset of cyclicity post calving (negative energy balance – trying to lactate and grow)
– Developmental defect – abnormal gonad

Front 8

What are causes for behavioural anoestrus?

Back 8

– Silent heat
– Nervous disposition
– Extreme environmental conditions eg heat stress
– Housing – some enviroments are detrimental to expression of behavioural signs of oestrus eg concrete/slatted floor, stall confined cows
– Disease: Lameness, illness

Front 9

How can anoestrus be caused by a prologend luteal function?

Back 9

– Prolonged dioestrus
– Pyometra
– Pregnancy
– Early embryonic loss – delay in return to oestrus (important cause)

Front 10

How does suckling influence oestrus/anoestrus?

Back 10

Ad Libitum Suckling Results in Suppression of LH Amplitude and Pulse Frequency
A reduction in suckling frequency increases LH secretion. Methods of shortening the postpartum interval to first ovulation in beef cows can involve weaning the calf or restricting suckling to 2 or less sessions per day

Front 11

How do can you detect anoestrus cows?

Back 11

• Best done before mating starts so that treatment can be instituted early
• General method: monitor for oestrus over a 3 to 4 week period – cows not detected in oestrus are classified as being anoestrous or “noncyclers”.
• Some producers may ask you to check cows for the presence of a CL which have not been detected in heat 3 to 4 weeks after mating has started. Disadvantage: you are already well into breeding period before treatment is instituted.

Front 12

Describe 2 methods for detection of anoestrus cows

Back 12

• Method 1. using observation or detection aids, note those cows detected in oestrus for 4 to 5 weeks prior to the start of mating.
Examine and treat non-cyclers a week before mating is due to start.

• Method 2. Tail-paint once per week, commencing 4-5 weeks before the start of mating. Once per week repaint cows with >50% of tail paint still remaining. After 3 to 4 weeks examine all cows with >50% tail paint still remaining. Select cows without a CL palpated for anoestrous treatment or just treat as anoestrous cows without checking ovarian status (if there is a chance of pregnancy you will need to pregnancy test the cows to rule out pregnancy as the cause of anoestrous).

Front 13

How could you manage nutrition & BC of dairy cows to treat/minimise anoestrus?

Back 13

• Optimise body condition score at calving: (target dairy: 4.5 to 5.5/8; aim for <5% < BCS 4.5 at calving)
• Appropriate transitional diet
• Optimise diet to match requirements
• Optimise dry matter intake
• Oral supplementation with propylene glycol has been trialed and can help reduce postpartum anoestrous interval. Difficult to implement.
• Optimise body condition for stage of lactation, reduce degree of body condition loss post calving (target < 0.45 loss in BCS between calving and start of mating)
• Calve heifers down before main herd begins calving – enables closer supervision and attention and increases the interval from calving to mating in seasonal calving herds. Gives them more time to commence cycling before mating.
• Delay mating eg split calving or year-round calving herd (may or may not be economic)

Front 14

How could you manage nutrition & BC of beef cows to treat/minimise anoestrus

Back 14

• Optimise nutrition to match requirements (not always possible)
• Agistment/supplementary feeding may be needed
• Mineral supplementation where deficient – eg feeding P during lactation is recommended where P is deficient
• Spike feeding – supplemental source of nutrition prior to calving or mating
• Early weaning
• Restrictive suckling (twice daily or prevent for 48 hours after removing CIDRs/Cue-Mate
• Optimise body condition score at calving

Front 15

How can progesterone be useful to treat anoestrus?

Back 15

Progesterone treatment – Helps reduce the sensitivity of the hypothalamus to oestrogen negative feedback & reduces the incidence of short cycles following induction of ovulation

Hint 15

• Duration of treatment with P4: min 7 days
• Combine with a treatment to synchronise follicular development and induce ovulation at the end of treatment

Front 16

Describe management strategies that can be used in beef heifers to reduce postpartum anoestous intervals following their first calving

Back 16

Aim for high heifer weight s at calving -> supplementary feeding
early weaning -> preserve condition and increase conception at the next mating