Fodder beet overuse could lead to low reproductive performance and metabolic disease.
Fodder beet is proving its worth in the dairy sector but there are some concerns and questions.
Looking to answer some of these, North Canterbury Veterinary Clinics vet Ben Allott spoke at Agricom's Fodder beet for the future, event in Gore last week.
Two of the key areas of concern in the dairy industry when using fodder beet was about reproductive performance and metabolic disease.
Dr Allott is based in Hurunui, where there are about 93 dairy herds, with an average 830 cows per herd, which worked at 3.5 cows to the hectare.
About 2000ha in Hurunui is planted in fodder beet.
''We've taken beet up in a big way.''
Addressing reproductive performance with beet, Mr Allott gave the examples of what had happened in Hurunui in the past five years.
Looking at 6-week in-calf rates, in the past five years they had been between 65-67%.
''We've just flat-lined really,''
At the same time, empty rates had risen to 16% to 20%, and mating lengths have been shortened dramatically.
''I think this is a really important thing to consider. In 2015 was the first season we weren't allowed to have inductions and prior to that we did have inductions ... that dealt with late calving cows. Mating length has declined from about 83-84 days and it has slashed about 10 days off it in the last five years.''
It was a vital piece of information which needed to be taken in to consideration when looking at why empty rates had risen, he said.
If fodder beet was having any impact on reproductive performance, Dr Allott said he would challenge why farmers were not seeing that in the 6-week in-calf rates.
''And empty rates, not in-calf rates, when I start slashing 10 days off a mating period, and in the middle of that period I lose the ability to bring late cows through early through artificial means, I can't induce them, I think we have to be a little bit careful to jump to conclusions about something like fodder beet affecting reproductive performance.''
When it came to metabolic disease and fodder beet, there were a few things farmers needed to aware of.
Preventing metabolic disease meant keeping body condition scores at calving at 5-5.5, as milk fever risk increased when BCS was less than four and higher than six, he said.
Sudden diet changes could also create issues, so maintaining dry matter intake through the springer period and early lactation was important, Dr Allott said.
Farmers also needed to look at magnesium supplementation and to not overfeed energy to springer cows which had a BCS over 5.
Potassium intake in springers also should be reduced, as high potassium intake in springer cows increased the risk of milk fever and udder oedema.
Calcium (limeflour) and phosphorus supplementation was very useful as well, but Dr Allott recommended talking to a professional on the need for phosphorus supplementation.
''As a general rule, feed springers a low calcium diet.''
Adding limeflour to the diet of colostrum cows and milkers once they had calved to boost calcium levels was a good idea, so they cows would not have to depend on the bone stores of calcium, Dr Allott said.
Multiple calf pick ups throughout the day would also help to reduce metabolic diseases.
Southern Rural Life