I am a huge fan of block calving: it makes a lot of sense, it focuses everyone’s attention on specific areas, and I think it can make the job of managing and feeding a herd a lot easier. However, I will admit I am a bit biased, as you will probably realise as you read on.
This article will concentrate on dairy herds because, if I am honest, I received very little information on block calving dairy herds during my undergraduate teaching, and learned on the job from a colleague from New Zealand.
Client choices
One of the choices your clients will have to make is whether they go for a spring or autumn block.
Spring means they can use the grass growth, but obviously milk prices tend to be lower, whereas they will often get more for their milk in the autumn, but will incur higher costs for feeding, and so forth.
Depending on a client’s contract, they may not be able to look at block calving if they have a requirement for year-round production. However, if they have enterprises with two or more herds, they could look at running one herd as a spring block and one as an autumn block, for example, to ensure they meet that requirement for year-round production. I have seen several herds use this method.
It also helps if switching to a block calving pattern, as you can allocate the cows to specific herds depending on when their calving falls.
Initially, it is important to highlight to clients that if switching from an all-year-round pattern, they are not going to get a really tight block for a couple of years (usually we are aiming for approximately 12 weeks), and they may have to cull more animals than usual for poor fertility.
This will also mean they need to ensure they have sufficient replacements if they do not want to buy in.
This can obviously be more easily achieved with sex-sorted semen. Exact numbers of heifer calves required can be calculated by considering calf mortality and a farm’s conception rates, for example.
Fertility
Cattle fertility has been on the decline, although this trend has started to reverse in recent years.
One of the biggest challenges facing farmers is detecting cows in heat to get them served. The modern dairy cow appears to show less obvious signs of heat and for less time, making it even more challenging.
Research has shown that the number of mounts a cow receives increases with the number of cows that are also in heat (Diskin and Sreenan, 2000), and this is more likely to be the case in block calving herds facilitating heat detection.
Compared to all-year-round calving herds, farmers do not have to get up or stay up late to do bulling checks, or check on cows calving all year round. I can recall one client moaning he had to check on the cows for calving on Christmas Eve, to which I replied that, as they were using AI, the solution was very simple: “don’t serve the cows to give birth around Christmas”.
I know of one large farm that took a management decision not to serve cows to calve over the Christmas period, to give the farmer and his staff a bit of a break. This affected his fertility KPIs, but it was a management decision and he still had excellent fertility.
While heat detection and calving will be very intense, it is a short period of time (if you get the block tight enough).
As aforementioned, I received very little undergraduate training on block calving dairy herds. From a veterinary perspective, fertility management is a bit different. I loved that once I knew a client’s calving date, I could work backwards to look at when I would be putting my visits in months in advance, and set dates for when I wanted the client to do things.
Vital for block calving is pre-mating heat detection. This should start approximately one month from the planned start of breeding to give the opportunity for all animals to have had a heat, and is a very intense period of heat detection to get oestrus dates for as many cows as possible – and to pick up any dirty, cystic or anoestrus cows that require veterinary treatment.
This enables this cohort of cattle to then receive veterinary treatment to maximise the chance of them conceiving in the block, and clients have a list of cows to look for bulling on specific dates once mating has started. Working out when veterinary visits may take place requires a bit of thinking. On the better-managed herds with tight blocks, I would often only do about five or six visits, with the final one taking place at least 42 days after the end of mating to pregnancy diagnose (PD) the whole herd.
Early PDs are mainly to gauge how well heat detection is going – so, a slightly different mindset to year-round calving.
Reproductive efficiency can have a big impact on the productivity and profitability of block calving herds, and within this is the need to frontload the block with heifers.
This is easily achieved using synchronisation programmes and ensures the fastest genetic gain, as sex-sorted semen means heifer replacements can be bred from the heifers. This also means dystocia should be avoided and the replacements will be sufficiently old enough and of adequate size for mating to calve in at two years of age (reviewed by Kerby et al, 2021).
In terms of fertility KPIs, how many cows and heifers calve within the first six weeks is a key measure of efficiency.
Disease control
Control of infectious disease is another plus point for block calving herds – especially for smaller herds.
Vaccines do not come in single or small numbers of doses, and trying to get vaccine schedules that meet the requirements for all animals is tricky – especially for youngstock. With block calving, everyone is pretty much at the same place, so vaccination scheduling is much easier for all ages of animals.
Perhaps the greatest issue I have seen in practice on disease control is Cryptosporidium, as this often builds up in the calf pens and, due to the intensity of calving, the infection pressure increases towards the end of the calving period, when we start to see calves with clinical disease, despite some farmers’ best efforts. However, if that is a known risk, you can work with clients to prevent it in future calf crops.
I have also found mastitis control easier to advise on, and I have gone through whole-herd data to advise which cows were being dried off with what.
Genetics
I can remember one client who had recently bought in a number of high genetic merit animals from the continent, selected for milk production – they were big girls.
The farm had just installed a new shed with cubicles large enough for the new members of the herd. This was a considerable investment and, coupled with handling facilities, meant I strongly advised them against making the switch, despite my love of block calving.
Cows in block calving systems tend to be a bit smaller and lower yielding. Livestock Improvement (https://uklic.co.uk/products-services) is a semen company that now has a base in the UK and offers sires bred from the best cattle genetics in New Zealand, but importantly, has a tool that allows you to see how their bulls perform under UK evaluation.
Other semen companies do offer bulls for block calving, and spring calving and autumn calving indexes (£SCI and £ACI) exist that allow block calving herds to look at across-breed genetic ranking for their production systems, and make sire comparisons.
Handling
Clients need to have sufficient handling facilities to be able to carry out multiple AIs, and these facilities need to be easily accessible.
If you only have limited AI pens, and accessing them requires multiple switching gates and shutting off sheds, and so forth, then how feasible is serving multiple animals on a daily basis for several weeks going to be?
This was another reason I advised the aforementioned farm not to go for block calving, as the infrastructure was not suitable.
Housing
Housing is a big one. Say a dry cow yard can cope with 30 cows – if a herd goes to block calving, does the client have suitable facilities to house the dry cows? This seems to be the biggest area clients often struggle with.
It might be that the lactating cow accommodation can be used or parts of it adapted. But with most cows being housed in cubicles and dry cows needing bigger cubicles, this may not be possible. Alternatively, clients could consider calving outdoors, but that does obviously carry some risks and can make handling cows difficult if they run into issues calving.
Calf accommodation also needs to be considered. I have had autumn block calving herds and they were on free-draining soil, so were able to keep calves outside in the autumn-winter. They had to be fed more and looked a bit hairy, but calves can do really well outside if you have appropriate land and shelter for them.
Nutrition
Block calving herds tend to be low input, low output systems, so you have to have good grass management, and one of the KPIs is the amount of milk from forage.
This means clients may need to invest in a plate meter to regularly assess grass growth. Some all-year-round calvers will do this, but in my experience not all, so this may be new to them. A plate meter allows clients to optimise pasture use efficiently and maintain its quality.
The Agriculture and Horticulture Development Board (AHDB) has some useful online links, including information about grass growth in the UK, how to measure and manage grass, plus it has a list of recommended grass and clover varieties for England and Wales (bit.ly/3NGKwAf). Useful podcasts and webinars are also available.
Soil management is also vital for grass and, again, plenty of information is available on the AHDB website. Clients switching to a block calving system may need to divide larger fields to manage grazing better instead of set stocking, and look at cow tracks to prevent lameness.
Conclusion
When considering switching to block calving, a number of factors must be considered. I have had farms ask whether they should make the switch and what I have previously highlighted are the things I think about.
One of the important things I have observed with block calving herds is farms tend to be highly motivated and share a lot of knowledge as part of very active farmer discussion groups, which can provide an opportunity for you to get involved.
Block calving is very popular in New Zealand – for younger people entering the farming profession, it gives them “time off” when the cows are dry, which can be very appealing.
A few shared milking systems exist in the UK that facilitate people who have not inherited a farm to get into the profession, which I think we need to help the industry survive.
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