Shade trees boost farm production
temperature recorded during the trial was 31.6 degrees Celsius.
Mean daily temperature ranged from 14-24 deg and the night temperature averaged 14 deg.
‘‘Nevertheless, the average maximum temperature was 10 deg higher in full sun than in the shade. The temperature reading from the cow’s back frequently exceeded 50 deg in both groups from 2-3pm,’’ he said.
Cows with shade made good use of it during the day and motion sensors showed that as the midday peak approached cows grazed closer to the trees.
‘‘The greatest revelation was cows with shade still did some grazing in the period of peak temperature. Between 3-6pm, they grazed more than no-shade cows and, overall, grazed 35 minutes longer per day.’’
Cows with no shade spent more time lying down during the heat of the day and suffered more heat loading, but both groups drank with the same frequency.
Rumen temperature often rose to 40-42 degrees at which time the cow had to have a drink. That indicated heat stress.
‘‘This was not seen in the afternoon, but more typically from 9pm to midnight following the ingestion of their biggest feed of the day from 4pm until sunset.’’
Planting trees not only provided shade but also soil stabilisation in hill country, extra income and added aesthetic value. Betteridge suggested creating a ‘‘magnet’’ to draw stock away from camping close to the margins of streams so both faecal nutrients and bacterial contaminants were less readily transferred to the water.
‘‘If trees are available then animals will always seek shelter for at least some of the time when the midday sun is hot.’’