During the calf's first month of life, it has a thermoneutral zone of 10-26 degrees. After one month, this changes to 0-23 degrees.

/Nordlund Wisconsin

If the calf is outside its thermoneutral zone, it needs more food. At minus degrees, you can count on up to 40% increased energy needs.

/Holm&Laue Calf manual

The most suitable relative humidity for calves is around 50-60%.

/Nordlund, Wisconsin university

It is important that the calf is not standing in draft. The definition of draft is 0.3 m/s, which is hardly noticeable to our senses. Smoke rises straight up at 0-0.2 m/s and is a good way to check air movements.
 
/Nordlund, Wisconsin university

A strewn surface or a deep litter bed accumulates urine and manure and when the calf is protected from drafts, for example through a hut, a microclimate arises in the calf with a considerable ammonia emission that can potentially affect the calf's airways.

Studies in natural ventilation for calves show that air circulation / air exchange is related to the number of bacteria in the air in the stables 'aisles, but not to the number of bacteria in the air in the calves' boxes. This thus indicates that a microclimate with, among other things, ammonia is formed in the boxes, which is difficult to ventilate away without exposing the calves to harmful drafts.

/Nordlund, Wisconsin university

The ammonia content in the stable must be below 10 ppm according to the Swedish Board of Agriculture.

Bacterial growth occurs exponentially over time. New straw on top of an old deep litter bed only gives a clean impression. A deep litter bed can easily contain 10 billion bacteria.

/Holm&Laue Calf manual

Hygiene is linked to infection pressure and infection pressure is linked to morbidity in calves.

/Tråven, SLU

At birth, the calf is a monogastric animal where the running stomach acts as a stomach, and the main breakdown and absorption of food takes place in the small intestine. Abdominal sputum adds enzyme and bile that breaks down protein, fat and carbohydrates. The womb is completely sterile at birth. The microflora that establishes itself there is affected by hygiene and the local environment and contact with older animals and feed materials.

At about 2 weeks of age, the calf begins to ruminate, then buffering saliva is formed which causes the pH value in the rumen to rise. It is only when the calf begins to eat solid food that the caretakers begin to develop, it is therefore important that the calf has access to fine hay.

/Ventorp, SLU

The newborn calf performs a series of instinctive behaviors, ie innate behavioral programs to get started suckling. The calf responds to key stimuli such as the angle between the leg and the body where it tries to suckle. Breastfeeding and sucking gradually develop very strongly into something that needs to be done to a certain extent, largely regardless of how much food the calf has ingested. When the calf lacks a teat to suck on, the calf tries to suck on other objects or individuals. From the age of seven days, the calf begins to socialize with other calves. Healthy calves also start spawning early in life. The first spawning takes place with the mother and later with other calves.

/Ventorp, SLU

Separating the newborn calf from the cow and placing the calf in a solitary box during the milking period limits the opportunities for the calves to perform natural behaviors and there are studies that show that calves that grow up find it more difficult to interact in groups as adults. New Canadian studies show the importance of seeing calves as social animals that should grow up in small groups. Younger calves can learn from older calves, which, for example, can stimulate feed intake.

/Agenäs, SLU

The calf's most important growth phase is 0-3 months, after 3 months of age puberty occurs and the calf must then grow at a slower pace for the udder to develop well. Since weight and hole largely determine sexual maturity, it is the calf's growth in the first three months of life that largely affects the age of insemination.

/Båge, SLU

Calves are generally said to need to grow 700-800 grams per day to be fit and healthy.

It is important that the calf is in good nutrition so as not to get sick.

/Tråven, SLU

The fact that the calves grow well during the first months of life is crucial because a high growth rate can later disrupt the development of the udder tissue and lead to a lower ability to produce milk in early lactation.

/Agenäs, SLU

Because calves are born without any antibodies in the blood, they lack resistance to infections and they are therefore dependent on getting colostrum from the cow. Colostrum is rich in immunoglobulins and they are absorbed by the calf and the antibodies circulate in the blood that protect against infections, so-called passive immunization. Immunoglobulins also provide local protection in the gastrointestinal tract.

The calf's ability to transfer immunoglobulins from the intestine to the blood is greatest at birth. This ability gradually decreases to cease after 1-2 days. Therefore, it is important to get colostrum in the calf as soon as possible after birth. The calf should receive 2 to 3 meals of colostrum during the first day. Each meal should be at least 5% of the calf's live weight. To maximize the calf's uptake of antibodies, at least the first two targets of milk should come from the first primer, as this milk has a much higher concentration of immunoglobulins than the milk from later primers.

/Ventorp, SLU

An interesting question is whether the calves grow best in a warm or cold environment. In an experiment where calves were housed in solitary boxes outside or inside, it was seen that the calves that went outdoors in calf huts grew better in the first month. This may be due to the poorer air quality prevailing indoors. But seen over the entire period day 1-52, there was no difference in growth. A study from Norway showed that calves that had been housed in a cold room grew worse in the first 4 weeks, if they did not get more milk to drink. But even in the second month, these calves (which grew worse in cold space) grew worse than the others despite having more to eat.

It is difficult to determine via these surveys what gives the best growth, but group boxing tends to be a little better from a growth point of view. Warm or cold housing is more uncertain about what is best, you have to look at the conditions you have on your own farm.

/Ventorp, SLU

During the first month of life, the calf has a need of at least 10 MJ / day, which corresponds to about 5 liters of whole milk. Studies have shown that calves drink significantly more than that. A Danish study showed that calves fed after drinking for 6 weeks on average drank 8.5 kilos / day. When calves go to suckler cows, it is difficult to know how much the calf ingests, but it is estimated that it is about 8.5-11.5 liters / day.

/Ventorp, SLU

The most common cause of calf mortality was shown in a sub-study in the so-called heifer project to be pneumonia and the mortality was highest during the first week of life. In the youngest calves, diarrhea was also one of the more common causes of death. There was an indication that the mortality of young calves was lower in herds that had their calves in smaller group boxes and feeding with a bucket compared to herds that had large boxes and automatic feeding or solitary boxes. The project also saw that larger crews had higher mortality.

/Svensson, 2006, SLU

Young calves should have access to water as early as possible. A calf that weighs about 50 kilos has a water requirement of about 5-6 liters per day. The amount of fluid they ingest through the milk soon becomes insufficient. Calves that have access to water start eating roughage and concentrates earlier. Do not give water by diluting the milk, as this impedes the ability to coagulate the milk in the rumen.

/Ventorp, SLU