More work and less milk from dairy cows with calves at foot – Teagasc

Dairy cows that rear their calves to weaning have a lower milk yield post-weaning compared to cows that do not suckle their calves, a first-of-its-kind cow and calf trial in Ireland has found.

The study carried out by Teagasc found that calves reared by their dam had higher weight gains pre-weaning, due to the higher milk volume they were consuming. However, by six months of age there were minimal differences in weight between calves given part-time access to their dams pre-weaning and conventionally reared calves. There were also no differences in cow health, but it noted increased stress at weaning for cows and calves that had been kept together from calving, along with increased workload for farmers.

Speaking to the Irish Farmers Journal, lead researcher Dr Emer Kennedy said the study looked at calf health, calf growth, calf behaviour, labour from a farmer’s point of view, milk production, cell count, condition score and locomotive score.

There were three groups for the study:

1 Conventional system: calves removed from dam post-calving and given colostrum.

2 Full-time system: cows and calves kept together on a full-time basis, both cows and calves turned out to grass from three days after calving and separated at milking twice a day.

3 Part-time system: cows milked once-a-day (in the morning), calves kept indoors in straw-bedded area, cows let out for grazing after milking and had access to their calves from 3pm until 8am the next day.

There were 18 cow and calf pairs in each grouping. Dr Kennedy and PhD students Alison Sinnott and Sarah McPherson, completed the study.

The viability of ‘calf-at-foot’ dairy models on Irish dairy farms was a commitment in the Programme for Government proposed by the Green Party.

Calf growth

The study focused on calves from birth up until weaning at eight weeks of age and also followed the calves in the early post-weaning period. Weight gains of the calves reared with their dam during the pre-weaning period were 29% higher than conventionally-reared calves. However, in the early post-weaning stage, at nine to 10 weeks, weight gain was higher for calves in the conventional system. This suggested increased stress on the calves reared with their mothers as they had to be gradually weaned off their dams and off milk.

At 11 weeks of age the conventional calves were 82kg, calves in full-time contact with cows were 92kg and calves given part-time access to cows were 89kg.

Dr Kennedy pointed out that of the calves that were kept with their dams and were turned out to graze at three days old, 25% had to be removed from the study due to illness, associated with early turnout, and over 40% of calves in this group needed antibiotics, as determined by the vet.

In comparison, just 6% of calves in the conventional system, and 17% in the part-time grouping needed treatment with antibiotics.

In terms of their behaviour, researchers found that calves which had contact with their dams were more vocal at weaning. Throughout the study, the calves who had part-time access to their dams showed more abnormal behaviours.

Cows

“When we took the calves off the cows for weaning, we expected the milk yield to bounce back. That never happened. Over a 35-week production period, in weeks 13 to 35 the yield never recovered and milk yield for the cows that had calf contact was down on average 22% per day,” Dr Kennedy said.

As a result, their total lactation parlour milk yield was 31% lower and milk solids yield was approximately 30% lower for the cows that reared a calf, compared the cows where the calf was removed at birth.

There was no difference in cow health over the study period, with no change in health scores, udder scores or milk leakage between the three cow groups.

The cows that had access to their calves on a part-time basis had increased weights and better body condition scores (BCS), however this is down to the fact that they were milked once a day. There was no difference in body condition score between conventional cows and those with calves full-time. At weaning, cows that had contact with their calves did lose weight, presumably as a result of weaning stress.

Labour

The study found that the cows and calves that were together full-time were the most labour-intensive group for the farmer as they had to be separated for milking.

Dr Kennedy said that implementing a system where calves and cows have contact would require “a lot of facility changes for farmers to cater for both the bonding and weaning process” as well as improved grazing infrastructure. There could also be questions around health and safety with farmers separating cows and calves on a twice-daily basis which could and would pose risks.