As lactation carries on, we start to see who the real high producers are. Often these will keep milking well despite the limited levels of feed, and will lose weight in the process.
Other cows (often lower PW cows) will now start to partition energy toward BCS gain, and get fat in the process. If we do not manage this well, then the herd average BCS may be okay, but the range of cows can be from 3.0 to 6.0 BCS by late autumn.
BCS Targets
DairyNZ studies have shown that the targets of 5.0 body condition score (BCS) for mixed age (MA) cows and 5.5 BCS at calving for first and second calvers are required to maximise profit.
These are not just nice targets to achieve. They should be the aim of every farmer at calving because it will affect your milk production and reproduction potential.
The study shows that the gain in milk production by calving cows at 5.0 BCS instead of 4.5 was 5.2kgs of MS — worth about $30 per cow.
Another DairyNZ study also showed that cows calving at BCS 4.0 compared with BCS 5.0 resulted in seven per cent less chance to be cycling at planned start of mating (PSM).
Cows that have not started cycling at PSM have a 16 per cent lower six-week in-calf rate and a higher empty rate of six per cent.
The best way to manage your herd through autumn
Start with individual cow body condition scoring your herd to get a realistic understanding of condition as opposed to just thinking they are okay 'apart from the odd light one'.
Dairy NZ's 'Body Condition Scoring Made Easy' booklet will help to guide you in condition scoring. Aim to do at least 70 cows to get a good cross section of the herd.
Or, get an accredited BCS assessor in to independently score your herd so you have impartial data to work from.
To find a local assessor, have a look on the DairyNZ website.
Once you have worked out what percentage of your herd are in the 4.0 BCS or lower category, you can decide what management changes you need to make to achieve days in milk and hit BCS targets by June.
The best options for protecting BCS right now
1. Work out what supplements are needed for winter and spring. Ring fence these, and don't be tempted to use them now. What supplements are available for this autumn? Feed budget this through from March to October.
2. Pregnancy testing and dropping stocking rate proactively (APC dependant) so that empty cows are not stealing valuable feed off your capital stock for next season will likely be a more profitable option.
3. OAD for all or one herd is an effective way of reducing BCS loss.
Milking cows through autumn on OAD will gain about 0.25 CS compared to being on TAD. If running two herds, then put the two and three year olds and any other in-calf MA cows that are 3.5 BCS onto OAD.
4. Once you know what options you have for feeding supplements or not, you can plan out what dates you will need to start drying off cows that are too light.
For example, a MA cow that is calving on July 20 that is 3.5 BCS needs to be dried off on April 10. An R3 year old that is 3.5 BCS needs to be dried off by March 20.
Be proactive in not letting BCS slip when you can alter management now to provide options for days in milk at a lower cost structure.
