4 min read
Improving your herd's reproductive performance starts with understanding and adjusting the calving pattern. Late calving cows often have less recovery time and hence a lower chance of getting pregnant in the first six weeks. Ideal targets for calving include having 88% of the whole herd and 75% of first calvers calved by week 6. To reach these targets, strategies such as early mating for well-grown heifers, monitoring heifer liveweight targets, targeted culling, maintaining optimum cow condition, maximising submission rates, and ensuring bull fertility can be employed. Professional assistance may be required for deeper analysis and personalised strategic planning.
If you’re looking to improve your herd’s reproductive performance, the first thing to consider is the spread in calving pattern.
Late calving cows are hard to get in calf because they have very little recovery time until mating starts. Excessive numbers of late-calving cows will reduce herd reproductive performance substantially.
The table below outlines the probable chance a cow has in getting in calf in the first six weeks or her chance of being empty based on the amount of recovery time she has between calving and mating.
|Calving to mating start date interval||6-week in-calf rate||Not-in-calf rate|
|More than 12 weeks||77%||7%|
|Less than 3 weeks||<40%||>20%|
What should we be aiming for?
Cows need to calve at least 6 weeks, and heifers up to 9 weeks before mating start date.
A targeted plan is required to take an extended calving pattern and make it more compact. Mating start and finish dates are the first place to start with addressing a calving pattern.
Use the Fertility Focus Report to review how the calving pattern of first calvers influence the calving pattern of the whole herd, and then the percentage of all cows cycling naturally pre-mating.
If possible, review multiple Fertility Focus Reports side-by-side comparing seasons over time.
Within the same season, does a 5-star whole herd calving pattern lead to a 1-star or 3-star 6-week in-calf rate? Why might this deterioration be happening?
Between multiple seasons does a 1-star 6-week in-calf rate lead to a 5-star whole herd calving pattern? How might that calving pattern have come about?
Calving pattern of the first calvers is the number one strategy to increase the proportion of the herd calving within the first three weeks of calving.
First calving cows need an extra one to two weeks to start cycling post calving, so yearling heifers should be mated one to two weeks earlier than cows. This should allow 85% of first calving to calve by the end of week 3, and they will have plenty of time to resume cycling and to be naturally fertile by the next mating start date.
Underweight heifers are more likely to have an extended calving pattern and not achieve submission rate targets at their second mating.
Assess your heifer's liveweights against liveweight targets to be sure you can optimise mating performance and get heifers in calf quickly once their first mating starts.
Plan your feed supply and demand from mid-lactation through to mating. As calving pattern improves review the mating start date to align early lactation feed align demand with pasture growth.
85% of the cows in the herd should be cycling naturally by the mating start date to maximise 3-week submission rates. If this is not the case; cow condition and heat detection practices should be reviewed, and appropriate action taken. After the primary areas are addressed have the cows checked for non-cycling. However, be aware that hormonal interventions do not fully compensate for poor pre-mating cycling rates.
Non-cycling treatment options for cows not detected on heat are being frequently updated as further trial results become available. This means that your vet should be consulted about current recommendations and programmes.
Fertile bulls that are managed well increase the chance of more cows getting in calf early. Explore the options of using short gestation bulls and avoid using bulls with longer gestation length, such as Herefords.