Every herd has them. A cow calves in, looks fine, and five months later she's on the list. A retained cleansing, then metritis, then off her feed, then lame, then empty at 150 days. By the end of the lactation she's in the cull group and nobody can quite say where it went wrong.
I'd argue it went wrong before she calved.
It's a waterfall effect, not bad luck
We tend to treat transition problems as separate things. Milk fever is one job. Ketosis is another. Mastitis, lameness and fertility each get their own protocol. The cow doesn't see it that way. For her it's one chain of events, and each problem makes the next one more likely.
Around calving she's hit with everything at once. Her intake drops. Her body switches from growing a calf to making milk. She's moved pens and mixed with new cows. Her immune system is at its weakest point of the whole year. Her uterus has to repair itself. Any one of those she'd cope with. All of them together is where things break.
Look at why cows leave herds. In one large US survey (USDA NAHMS, 2007), reproduction accounted for 26% of culls, mastitis 23%, poor production 16% and lameness 16%. Between them that's four out of five cows. Most of those problems can be traced back to the few weeks either side of calving.
The warning signs show up early
This is the bit I find most useful. In one study (Huzzey et al., 2007), cows that went on to develop metritis were already eating less before they calved. Not after. Before. Intake in those cows was down in the week before calving, and they then ate less for weeks afterwards.
So the metritis cow isn't a random event. She was telling you something ten days earlier at the feed barrier.
Those cows paid for it too. Healthy cows gave roughly 8 to 10kg a day more milk than the metritis cows between day 8 and day 21. That's before you count the cost in fertility.
Crowding the close-ups
If I could change one thing on 90% of the dairy farms I visit, it would be the space in the close-up and fresh pens.
A cow in the last few weeks before calving needs somewhere to eat and somewhere to lie. When stocking rates go up, intakes go down. Dry matter intakes before calving drop as feed space gets tighter.
Fat cows, calcium and the rumen
Three nutritional things drive a lot of what goes wrong.
Body condition. Cows calving too fat eat less, mobilise more body fat and end up with high NEFA in their blood. Across 100 herds (Michigan State University, 1995), cows with high NEFA two weeks before calving had noticeably more ketosis (17% vs 10%), displaced abomasums (10% vs 3%), retained cleansings and fresh cow mastitis. Too thin is no better. Lower peak, lower lactation yield. Lose more than a full condition score in early lactation and fertility drops.
There's a hoof angle to this too. The fat pad inside the claw, the digital cushion, is the cow's shock absorber. Thinner cows have thinner cushions. Lose condition fast and that cushion goes, and sole ulcers follow.
Calcium. Milk fever isn't just a cow down in the yard. Low blood calcium weakens every muscle, including the rumen, the uterus and the teat sphincter. That means more displaced abomasums, retained cleansings, metritis and mastitis. Cows that had milk fever were also nearly five times more likely to get sole ulcers (Sogstad et al., 2006). Calcium is also needed to build good claw horn.
Rumen acidosis. Too much starch, slug feeding, cows missing out at the barrier. The rumen pH drops, bacteria die off and release toxins that leak into the bloodstream. That drives inflammation right through the body, and it shows up as weak feet and poor fertility. Loose, inconsistent dung, cows off feed and low butterfat are the early signs.
Mastitis costs more than milk
Most people know mastitis costs milk and treatment. Fewer realise how much it hurts fertility.
Around 60% of new udder infections start in the dry period, not in the milking herd (Green et al., 2002). And heifers aren't the clean sheet we assume. Several studies found the majority of heifers already had an udder infection at calving (Oliver et al., 1992). Heifers with a high cell count at first recording gave less milk for the rest of the lactation.
Then there's fertility. In a very large study (Lavon et al., 2011), conception rate was around 39% in uninfected cows. Cows with a new infection or chronic mastitis dropped to around 32%. Cows that got mastitis between first service and pregnancy averaged 144 days open, against 85 for clean cows. Cows with mastitis in the first 45 days were 2.7 times more likely to abort (Risco et al., 1999).
The inflammation messes with the hormones that control heat, ovulation and holding a pregnancy. You can have a perfect breeding programme and still lose to a sore quarter.
Lameness touches everything
A lame cow moves less, lies down and gets up less, drops down the pecking order and eats less. On robots she makes fewer trips to the box, which is one of the first things I look for in AMS herds.
Her fertility falls apart as well. In one study (Melendez et al., 2003), lame cows had a first service conception rate of 17.5% against 42.6% in sound cows. They had more than twice the cysts. Nearly a third were culled before they'd even been served.
Trace minerals
Zinc, copper and manganese all matter for immunity, skin, hoof horn and the lining of the gut. Liver levels of some of these dip around calving, right when demand is highest. Stress and heat stress make the gut leaky, and zinc plays a part in keeping it sealed.
What I'd look at on farm
- Feed space and stocking rates in the close-up and fresh groups, especially when calvings bunch
- Condition score at drying off and at calving. Aim to hold it, not change it, through the dry period
- Close-up intakes and behaviour in the last ten days. Who's hanging back?
- Calcium strategy for older cows
- Rumen health in the fresh group. Dung, cudding, rumen fill, eating and rumination minutes
- Dry cow and heifer udder health, and cow cleanliness
- Mobility scores, and robot visits if you're on AMS
Transition is where the whole lactation gets decided, so small misses there cost the most.
None of this is new. Fix the few weeks either side of calving and a lot of the cull list sorts itself out.