High Submission Rates Essential for Compact Calving
Spring calving breeding programmes will begin on the majority of dairy farms over the next few weeks. The harsh weather in March running through the first week of April has exhausted all reserves of silage, straw, maize and grass covers on many farms.
Body Condition Score of Freshly Calved Cows
Freshly calved cows have lost excessive body condition score (BCS) on many farms. Many farmers have been reluctant to supplement with the extra concentrates required by cows to avoid excessive BCS loss. The freshly calved cow has an immune system, which is most severely challenged for the first few weeks post calving. The temptation to put freshly calved cows out to grass over the past few weeks has resulted in many cows losing excessive bodyweight loss, impaired uterine involution and a consequent increase in the percentage of cows with womb infections.
Cow Not Cycling
In a recent experiment involving in excess of 3,000 cows, those cows which started cycling in week 3 post calving, were four times more likely to be in calf by 210 days calved than those cows which took up to 6 weeks post calving to resume cycles.
If cows are “fit” pre-calving and do not experience trauma in the period immediately post calving, a high proportion will resume heat cycles by the time they are three weeks calved. It is important to note that the majority of those “first heats” are silent with no overt signs of heat.
Major Controlling Influence on Submission Rate
The dye is cast at this stage in terms of reproductive outcomes for many cows to be bred over the next few weeks. However, we as farmers, have a major controlling influence on submission rate, which is the primary driver of compact calving.
If we cannot detect the cows in heat, we will not get them in calf! Many farmers put stock bulls in with the herd as they either do not have the confidence in AI to get cows in calf or consider heat detection too much of a challenge. Running a stock bull with the herd can actually “hide” problematic breeders and literally puts all your “eggs in one basket” in terms of future herd replacements.
AI gives us Access to a Greater Genetic Pool
The use of AI gives us access to a greater genetic pool plus the option of the use of sexed semen. Therefore, now is the time to take up the 6 week challenge to detect heats for the use of AI with either sexed or unsexed semen, identify problem breeders before they become culls and reap the financial rewards associated with a high heat detection rate. Teagasc have attributed a €250 cost with missed heats.
Various approaches have been taken by farmers to achieve a high submission rate. The target submission rate has to be 90pc plus. Visual observation for five 20-minute periods at defined times will result in the desired submission rate for cows that are “fit” for breeding. Tail-paint applied to the tail head is an excellent aid to heat detention, but requires diligent management to achieve the desired results. Submission rates of 90pc plus has been achieved using tail-painting, three 20-minute observations periods daily. Unfortunately submission rates between 60pc and 70pc are the norm on dairy farms.
Aids to Heat Detection
Novel approaches to achieving high submission rates include the use of collar mounted accelerometers and ultrasonography as aids to heat detection. In a recent independent study conducted by Reprodoc revealed that the MooMonitor developed by Dairymaster achieved an 83% heat detection rate when assessed against a gold standard using ultrasonography.
Ultrasonographic Assessment of the Reproductive Tract (USART)
Finally ultrasonographic assessment of the reproductive tract can be used as an aid to maximise submission rates. The technology can provide the farmer with details of those cows fit for breeding, problem breeder cows and when to expect cows in heat. This gives farmers greater focus to maximise submission rates for fit cows and identify problem cows for veterinary intervention.
Dr. Dan Ryan is a Bovine Reproductive Physiologist and can be contacted on www.cowsdna.com