InCalf

InCalf is a programme which was created in Australia but adapted for New Zealand dairy farmers. Its mission statement is "To enable dairy farmers to achieve measured improvement in herd reproductive performance”.

To improve reproductive performance farmers must be able to:

• Assess the current reproductive performance of the herd

• Assess their scope for improvement and the likely benefits;

• Determine their options for change; and

• Implement their chosen changes

Our dairy industry now has a targeted Six Week InCalf rate (6WICR) of 78%, which is achievable but currently a long way above the average NZ herd performance. Herds which a have high 6WICR will also have low empty rates.

The Veterinary Centre has 12 trained InCalf advisors, who can help you improve reproduction using the process above. The key starting point is to get quality data to analyse through ‘foetal aged pregnancy testing” which is done from mid-January to mid-February (6-8 weeks after the end of AI). We do this using the Infovet programme. Using this information we can assess the eight key areas which have been identified to have a combined influence on a herd’s fertility. These are:

 

Calving Spread

A mature cow takes an average of 45 days to resume cycling after calving. The sooner she calves after the Planned Start of Calving (PSC), the more likely she will cycle on her own before the Planned Start of Mating (PSM). Also the more cycles she has before mating begins the higher her conception rate when mated will be. Too many late calving cows reduce herd fertility.

 

Nutritional Status and Body Condition

A good measure of a cow’s nutritional status is her body condition or the change in body condition over a period of time. A 1-10 Body Condition Scoring (BCS) System is used in New Zealand. The optimal targets for reproductive performance are:

BCS at calving for a mature cow is 5.0-5.5. With not more than 15% of cows above or below these figures. The target for heifers is 5.5-6.0.

• Not more than 1 BCS loss post calving.

• Not more than 15% of cows below BCS 4.0 at PSM.

•  Maintenance of a positive energy balance through the mating period.

• Cows should be BCSed on a regular basis to ensure these targets are being met.

Trace mineral status is also important as deficiencies may cause anoestrus, increased risk of uterine infection and early embryonic death. Regular herd monitoring via blood test and liver biopsies pre-calving, premating and dry off can identify problems early.

 

Heifer Rearing

How you rear your young stock not only has a big bearing on their lifetime milk production potential but also their ability to get pregnant. The genetic live weight target for a herd or line of animals can easily be sought from your genetics company. Heifers should reach;

•  30% of their mature live weight by 6 months of age.

• 60% by 15 months (first mating) of age.

• 90% by 22 months of age.

Your vet can help you set up an animal health programme for young stock which will include a regular weighing programme to ensure targets are being met.

 

Non-Cyclers and Heat Detection

To have good 6WICR you must achieve good 3 week submission rates (SR). Non-cyclers and poor heat detection will both influence the SR.  The best way to prevent non-cyclers is to ensure the proceeding points have been managed well, but once you get to the start of mating early identification and hormonal treatment of these cows will be financially beneficial.

It is important that aids be used to help with accurate heat detection. Tail paint, Scratchies and KMars are the most commonly used methods, but they rely on regular maintenance and close scrutiny for the best results.

 

Genetics and Artificial Breeding

Management practices have the greatest bearing on repro performance, but long term strategies include selecting bulls which have higher fertility breeding values which they will pass onto their daughters. At the time of artificial breeding it is important that cows are held in a stress free environment and mated within 0-24 hours of the first signs of standing heat. Good facilities should be set up to assist the technician to perform a swift and comfortable job.

 

Cow Health

Lameness and mastitis have been shown to have an indirect impact on reproduction. Trace element deficiencies have been covered under nutrition. Uterine infections can be minimised through good nutritional management, but early detection and treatment of infections 2-4 weeks post calving markedly increase a cows chances of getting back in calf.

The main infectious diseases affecting reproduction in New Zealand cows are Nepospora and BVD. These are complex diseases and should be discussed with your vet.

 

Bull Management

Most local herds will AB cows for a 4-8 week period, before following up with bulls to catch any cows still not pregnant. Inadequate bull numbers, lameness, low libido and small size are the most common factors in bull failure.

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