Huatokitoki Shade Research

Keith Betteridge’s research at the Parsons Estate Farm has found that on days when the temperature is higher than 25degC, cows with shade will graze 30 to 40 minutes more a day than cows without shade.

The research is part of a larger Sustainable Farming Fund project in the Huatokitoki Catchment. This trial has funding from the SFF, the Foundation for Science, Research and Technology, and from AgResearch. The project is called “Angus Cow Response to Heat Stress in New Zealand” by AgResearch staff Keith Betteridge, Des Costall, Adrien Lacroix and Sam Martin, with farmer Brenden Reidy.

Huatokitoki catchment farmer Brenden Reidy, who manages the Parsons Estate farm for the Public Trust, offered the farm for the trial. “It was all in keeping with the whole group philosophy about having resilience and sustainability in our businesses, which includes protecting our land and improving our production.”

“And as a manager I have to justify my expenditure to the Public Trust. They are proactive in having modern, highly productive farms. If we can prove that planting trees also increases production it gives me justification for more plantings.”

The project came about because half the farmers in the SFF project felt that if animals were given shade they would graze less, and therefore grow more slowly. The other half felt that animal welfare had to be considered.

All this work needed was some GPS collars to track cows 24 hours a day, but with all the extra sensors, the scientists were able to find out a great deal more information than they initially anticipated.

The trial was run over three weeks in summer, with some cows in paddocks with shade, and the other cows in paddocks with no shade. There were six cows monitored in each paddock, with a stocking rate of 2.1 cows and calves per ha.

The scientists used a GPS to record movement and location, a motion sensor, a rumen sensor, skin temperature sensors, button loggers for temperature in and out of the shade, a surveillance camera to validate the sensors and two full weather stations.

On days when the temperature is higher than 25degC, cows with shade graze another 30 to 40 minutes more a day than cows without shade, Keith Betteridge’s research at the Parsons Estate farm in Central Hawke’s Bay has found.

The reason why cattle graze for another half an hour a day when they are offered shade on hot days is because the average daily maximum temperature under the trees is 10 degrees cooler than in the open.

On the hottest day without shade the maximum temperature was 43degC but on that same day the maximum temperature in the shade was 32degC.

The extra half hour of grazing is usually in the period from 3-6pm and around 7-9pm.

Sensors on the backs of these black Angus cows measured temperature which reached over 50degC. That is a combination of sunshine and metabolic heat from digestion, Keith says.

The researchers were amazed to measure rumen temperatures of more than 40.5degC, even though warm-blooded animals have a near constant temperature. Sometimes the cows get so hot they have to get up and have a drink, even at midnight.

They also measured the number of drinks the cows had during the day, but it was no different between shaded and unshaded paddocks. The number of drinks was found from the rumen temperature, which dropped significantly when the cows had a drink.

In summer, cows and sheep often shelter under trees from as early as 8am. They have been grazing for two to three hours from sunrise, and metabolic heat, which is heat generated from digesting the pasture, makes them uncomfortably hot even at this early hour.

Keith says ethically, farmers should be considering planting more trees for the improved wellbeing of their animals. Animal welfare should be a serious consideration for farmers, he says.

In terms of production, these animals with shade are likely to be growing faster and using their feed more efficiently.

He wants to carry out liveweight gain studies over a six-week period now to test this hypothesis.

Space planted trees not only provide summer shade but also stabilise the soil in hill country, as evidenced during the local storm of Easter 2010.

The only negative the research has thrown up is animals camping under shade trees may result in localized concentrations of faeces and urine, which could enter the stream as water pollutants.

Ideally, plantings should be a short distance from waterways to minimize this effect. This applies especially to larger streams where significant riparian strips should be established to ensure animal wastes are not deposited into the water.

The research also raises a few more questions Keith would like to answer:

1. Do cows with shade, and stocked at the same density as cows without shade, grow faster in summer?

2. What are the actual effects of and animal response to, winter cold, wind and rain on animals, both with and without shelter?

For Brenden, the research has created more questions than answers, but his key messages are that farmers have to deal with extreme temperatures with their livestock, and the animals do react to that. He says figures are indicating production is higher from animals with shade, but more work needs to be done on this.

He’s looking forward to more detailed information to come out of the trial, particularly around water quality and how farmers can improve troughing techniques to supply better quality water to animals.