This season, New Zealand’s dairy herd recorded an all-time high 6-week in-calf rate.
The industry goal is to have a 6-week in calf rate of 78%.
Even if we achieved an interim goal of 72% this would result in an additional 17kg milk solids (MS) per cow and reduced carbon emissions intensity of 2.9% CO2e/kgMS, not to mention savings on feed, reduced replacement rate, and increased ability for discretionary culling. There is no silver bullet to achieve outstanding reproductive performance. Rather, it is about having great systems on farm that are consistently applied.
Next month, dairy farms around New Zealand will be in full swing with seasonal mating on top of milking, and keeping on top of your herd’s health. Now is the time to prepare.
Focus on getting your cows in-calf early
By calving early in the season, cows have more opportunity to cycle well before the planned start of mating and are more likely to get in-calf.
Co-op Programme Manager (Veterinary) Sue Campbell says cows must be back in-calf within 12 months of calving. Early calving fits with New Zealand’s competitive advantage using lower cost, pasture-based, lower emission feed with increased days in milk improving efficiency compared to production in the shoulders of the season,” she says.
“We have a complete circular system with one season running into the other. It’s really important that we have cows in the right body condition score at calving because that sets them up for the whole season and for the subsequent season. With cows that have poor reproductive performance or are going to calve late, you are fighting a losing battle to keep them in the herd”.
The herd fertility cake
Reproductive performance is the interaction of the herd's fertility and the environment, DairyNZ use the ‘herd fertility cake’ to look at the key factors influencing reproductive performance. Growing calves and heifers is essential to producing great reproducers. Healthy calves lead to healthy and well grown heifers that are then more likely to get in-calf when they first cycle.
Colostrum management is key to ensuring daily weight gains are achieved. Sue recommends increasing nutrition levels when it’s cold so calves can continue to grow despite increased energy demands of maintaining their body temperature, and ensure they have well developed rumens. Ideally calves should be consistently eating > 1-1.5kg meal/day before weaning onto high quality pasture.
If you can measure it, you can manage it
Weighing heifers is still an opportunity for some in New Zealand. It’s a crucial piece of the puzzle to improve reproductive performance. Heifers should be weighed every eight weeks. This allows farmers to take action as required.
Sue says research has found heifers that were a greater proportion of their 21-month live weight target (LWT) at 12 months of age produced more in their first lactation and cumulative three-year milk yields than heifers that were a lesser proportion of their 21-month LWT at 12 months of age.
“Increased growth in early life of New Zealand dairy heifers is beneficial to future milk production. Weighing heifers with scales (and comparing their weights to where they should be) is critical to achieve this. Heifers should be 60% of their mature weight at 15 months of age (when first mated). On average though, they’re about 5% lower than what they should be, but the worst ones are 15% lower than what they should be. The best estimates for up-front loss is 2kgMS for each percent behind the 22 month target, which adds up,” she says.
“You’ve got to measure to monitor. One of the challenges is farms just don’t have scales, and for some it’s not something that is common practice, and it absolutely should be. It should be standard practice. Visual checks do not cut it when you’re wanting to ensure the best gains.”
Know your numbers
It is important farmers keep an eye on progress throughout the mating season.
“Focus on the 6-week in-calf rate. It’s only a short window of opportunity to get it right. Liaise with your vet and breeding provider to ensure the best AI management and bulls that are fit and healthy. You’ll need at least two bulls per 30 cows to allow for rotation and have them in place at least a month before mating,” Sue says.
“Remember to review your data at the end of the season to identify opportunities through your Farm Insights Report (due out later this year), and your farm’s Fertility Focus Report. It will allow you to benchmark your 6-week in-calf rates, not-in-calf rates, and mating length.”
- Record pre-mating heats, with tail paint on at least six weeks before the planned start of mating (PSM)
- If <75% of cows have cycled 10 days prior to the PSM there is an issue.
- Have at least 90% of your herd inseminated in the first three weeks of mating
- If less than 81%, seek advice.
- Aim for 60% of inseminations to be successful (positive pregnancy test) – regularly assess this during mating to identify issues
- If less than 53%, seek advice.
- Aim for at least 78% of your herd to be in-calf in the first six weeks of mating
- If less than 68%, seek advice.
- Not-in-calf rates should be below 10-12% (the percentage of the herd that failed to become pregnant during both the AB and bull mating periods)
- If greater than 17-14%, seek advice.
Talk to your local field team, veterinarian, or breeding company for more information on improving your 6-week in-calf rate. For more information check out DairyNZ’s In-Calf book.