If an animal is unable to lie down, rest, and ruminate it is not expressing natural behaviour.
Winter grazing practices that compromise animal health and welfare have no place in modern farming, The New Zealand Veterinary Association says.
"The time has come to transition away from winter grazing practices that result in poor animal welfare for livestock," says Veterinary Association chief veterinary officer Dr Helen Beattie.
Intensive winter grazing is commonplace and can lead to poor animal welfare and environmental damage, particularly during prolonged periods of wet weather, she says.
"We need to take a second look at these practices, and when animal welfare isn't protected, find solutions that rectify this safely."
Beattie says poorly managed winter grazing can lead to livestock standing knee-deep in mud, without adequate shelter.
In many cases these practices are in breach of section 4 of the Animal Welfare Act 1999, which requires the physical, health and behavioural needs of animals to be met.
These needs include proper and sufficient food, proper and sufficient water, adequate shelter, and the opportunity to display normal patterns of behaviour.
"For intensive winter grazing to meet these needs, dry, sheltered areas with adequate lying space are required, as is access to fresh water, and also adequate nutrition. A monoclonal forage crop diet in late pregnancy is not likely to adequately meet all dietary needs," she says.
"When the ground underfoot is wet and muddy, cows lie down less than they might otherwise choose to, and sometimes this is not until they are exhausted. If an animal is unable to lie down, rest, and ruminate it is not expressing natural behaviour.
"As we begin to experience more rain and cold weather, farmers need to be particularly aware of the risks these practices pose to livestock."
Ideally farmers should plan ahead at crop planting time, so they can reduce the risks to their livestock, and the environment during crop use. Farmers should be considering winter 2020 now, and how to approach all future use of crops, given this grazing practice will be under ongoing scrutiny.
While using a winter crop can be a successful way to feed stock, including achieving weight gain, body condition score by itself is not a good metric to judge the overall health and welfare of an animal.
Beattie has advocated strongly for a national level, pan-sector solutions working group to be formed.
"This approach was very successful in working through the challenging issues of inductions and bobby calf welfare," she says.
A collaborative approach is needed to assist farmers through a fair and just transition away from winter grazing practices where these practices compromise animal and environmental health and welfare.
She says winter grazing practices need not compromise animal health or welfare. "Where there are negative outcomes, solutions need to be sought that are practical and do not have unintended, negative consequences. The sector should help farmers navigate through an issue that has effectively been endorsed for many years. We need for there to be a team effort, to help farmers, where this is required."