26/04/2026
Rearing the Jersey Calf
This came out of a panel discussion I was part of at the Jersey NZ Conference, where we were talking through some of the long standing (and often negative) narratives around Jersey calves.
And one point kept coming back to me, that Jersey calves are not small Friesians. And to be fair, I could say the same in reverse, Friesians are not large Jerseys. Crossbreds are also not just “somewhere in the middle.”
Different breeds bring different genetics, different frames, different metabolisms, different strengths, and different pressure points. That is not a problem. That is the opportunity.
We have this habit in farming of building a system, then expecting the animal to fit it. But good stockmanship is often the opposite, we call it calf (or cow) centric on farm here, that it we build the system around the animal in front of you.
It is a bit like dogs. A greyhound and a husky are both dogs, but nobody sensible would feed them, house them, exercise them, or care for them exactly the same way. A greyhound is lean, fine-skinned, fast, and more vulnerable to cold. A husky is built for insulation, endurance, and weather. Same species, both dogs, different breeds, completely different biological package.
That is Jerseys. Not wrong. Not lesser. Not difficult for the sake of being difficult.
Just different. And once we understand that difference, they make a lot more sense.
There's a huge amount of nuanced science in and around all of this. It's Sunday of a long weekend, so I'll keep this post high level rather than diving right in.
A Jersey calf is born lighter than a larger-framed breeds of dairy calf. They have a higher surface-area-to-bodyweight ratio, which means they lose heat more easily. Young calves generally have very little body fat at birth, around 2–4% of bodyweight and that fat is one of the small emergency energy reserves they have available for heat production and early survival. Smaller calves have less total reserve sitting in the tank, which is less to come and go on if something goes wrong.
So when a Jersey calf gets cold, they do not just “look a bit tucked up”. They are shifting their energy budget. Energy that could have gone into growth is being redirected into staying warm. Energy that could have supported immune function is being spent on maintaining body temperature. And because young calves are not yet functioning ruminants, they do not have the same internal heat production from fermentation that an older animal has. They are much more dependent on the energy we provide, the shelter we provide, and the environment we place them in. If you spend more of your energy on keeping warm and less on growth and immunity, then you get exactly that, less growth and less immunity.
That is why the word responsive matters. A Jersey calf is responsive because their biology gives them less buffer. Less spare fat. Less thermal mass. Less margin for cold, hunger, poor colostrum transfer, competition, or sudden changes in feeding.
But that same responsiveness is also the upside. Because when the system matches the calf, Jerseys can respond to the positive faster than other breeds. If you compensate for the thermal mass and energy requirements early on, reduce competition, manage hygiene, keep bedding dry, and give them a feeding system that matches their size, then they don't just cope, they fly.
That is not fragility. That is efficiency being allowed to express itself. In business systems and in life, we only get high effiencey we run close to the wire and don't use any excess, which is the total biology of a Jersey calf. Programmed for efficiency, and nothing extra.
And this is where the nutrition conversation needs more nuance. The answer is not simply “feed more milk”. It is feed the right animal, the right nutrition, in the right way. Jersey calves are smaller, so their intake needs to be managed relative to bodyweight. They may not need the same total litres as a much larger calf to be receiving a very high intake for their size.
That is why litres of milk are only part of the story and nutrient density matters more. Jersey milk is naturally richer. Research comparing Jersey and Holstein milk repeatedly shows Jersey milk has higher fat and protein percentages. That matters because it gives us a biological reference point, the Jersey calf is not necessarily designed around large volumes of lower-density liquid. She is designed around a richer, higher fat fuel source. So when we choose CMR or design a milk-feeding system, we need to think beyond volume.
How much energy is in the litre?
How much protein?
How much fat?
What total solids?
What mixing rate?
What feeding frequency?
What temperature?
What teat flow?
A more nutrient-dense feed, with an appropriate fat and protein profile, can help deliver energy without simply pushing more liquid volume into a smaller calf. The goal is not to flood the system, the goal is to fuel it.
And then we need to measure the calves themselves properly. If we only measure kilograms per day (average daily gain - ADG), bigger calves will often look better. Of course they will. They started bigger, that's just maths.
If a 30 kg Jersey calf gains 600 grams a day, that is 2% of her bodyweight.
If a 45 kg calf gains 800 grams a day, that is 1.8% of her bodyweight.
In other words, the smaller calf may be putting on fewer total kilograms, but she is growing faster relative to the size of animal she actually is. That is efficiency.
Because farming is not just about size (despite the many who like to profess otherwise, while I sit there wondering what, exactly, they are trying to compensate for) Profitable, productive and performance farming is about efficiency. It is about return on feed. It is about how much growth you get for the biological package you are working with.
When we measure Jerseys properly with tools like percentage of bodyweight, multiple of birthweight, feed conversion, and performance relative to mature size, then the picture changes. They are not fragile, fussy, poor doers. In the right system, measured with the right ruler, Jersey calves can outperform bigger calves.
That was the key point in my Jersey Conference presentation. Jersey calves need to be understood, fed, and measured as Jersey calves not treated as smaller versions of another breed. The same principle actually applies across all breeds.
A Friesian calf has strengths.
A crossbred calf has theirs.
A beef-cross calf has theirs.
A Jersey calf has theirs.
That is not breed wars. That is precision. That is stockmanship. That is the joy of farming animals.
The animal tells us what the system is doing. Jerseys just tend to tell us quickly and a lot more honestly. And I think that is a gift. Because they do not just show us the downside when something is wrong. They show us the upside when something is right. They turn around quickly.
They respond to warmth. They respond to accurate feeding. They respond to nutrient density. They respond to excellent colostrum. They respond to being managed as the animal they actually are. And once they get momentum, they can be bright, sharp, persistent, efficient little growth engines.
Maybe the real conversation is not whether Jersey calves are hard. Maybe the real conversation is how much potential we unlock when we stop asking every calf to fit the same mould. A greyhound should not have to live like a husky. And a Jersey calf should not have to prove herself by pretending to be something else.
And maybe that is the future of better calf rearing. Not growing calves bigger for the sake of bigger, but more accurate, more efficient, and more calf-centred. It is understanding the animal in front of us, feeding and managing them for what they actually need, and measuring her in a way that reflects what they are capable of.
Because every calf has potential, but potential still needs the right system behind it. Our job as calf rearers is to build that system
