Research looks at toilet training for cows

01-04-2010 | Jackie Harrigan

Can cows be toilet trained to help reduce nutrient loss?

Research has shown the amount of nitrogen (N) accumulated in the soil in dry summer and autumn periods is critical for determining N leaching rates during subsequent winter drainage periods.

If cows can be trained or moved to urinate somewhere other than their paddocks, N can be captured for controlled application rather than being lost to leaching in wet soil.

Research presented at last month's fertiliser and lime conference at Massey University showed that by removing cows from the paddocks to stand-off pads for up to 16 hours a day in a recent trial the urine loading on the pasture was reduced by 30% without compromising the pasture intake, milk production, body weight or body condition score of the cows in late lactation.

The joint DairyNZ/AgResearch project run by Chris Glassey in March and April, 2009, separated 48 Holstein Friesian cows into three treatment groups and gave them access to pasture for either four hours after each milking (2x4), eight hours between morning and afternoon milkings (1x8), or for 24 hours excluding milking times (control). When not grazing, the 2x4 and 1x8 groups were stood off in a plastic-lined loafing area with a woodchip surface.

After storage, this urine could be returned to pasture and crops as fertiliser at a time of year when nutrients are more likely to be taken up by actively growing plants (eg late spring). Spread of the urine would be more even across a land area than when deposited by cows in urine patches.

There was no difference in pasture intake (mean 10.2kg DM/cow/day), milk production (mean 10.3kg/cow/day) and body weight or body condition score change (mean 3.7kg/cow/week and -0.2 units/cow/week) between the treatments.

Urinations on pasture and laneways were reduced from 85% (control) to 56% (1x8) and 50% (2x4) of total urinations. The estimated capture of 9l/cow/day is around one-third of daily N output and relates to 119g/N not subjected to loss in the following winter drainage period.

Similar research at Massey University by Christine Lindsay and others into duration-controlled grazing practices is showing comparable results, with reduced nitrate N losses in the drainage season when cows are removed from the pasture between milkings.

A large-scale, long-term grazing trial investigating the effect of duration-controlled grazing on the quantities of N, phosphorus (P) and faecal microbes lost in drainage and run-off from grazed pasture was established at Massey University No 4 dairy farm in 2008. Pasture accumulation and cow intakes were estimated over 14 plots, each of which was drained so the water could be sampled and analysed for N, P and faecal microbes.

Grazing treatments were alternated between day and night grazings of four-hour duration on seven plots (duration-controlled grazing, DCG). Standard grazing practices were employed on the other seven plots (six-hour day graze or 12-hour night graze), with the average stocking rate the same for each treatment.

The treatments began towards the end of the 2008 drainage season, hence there were no differences in drainage water nitrate-N losses between the treatments. However the 2009 season showed a 46% reduction in the dung deposition rate on the DCG plots and a 41% (or 5.2kg N/ha) reduction in nitrate-N leaching over the drainage period (February-October 2009) from those plots. Pasture accumulation and intakes by the cows were similar for both treatments for the 2008-2009 season.

Both research programmes showed an opportunity existed to maintain the performance and welfare of grazing cows in late lactation while capturing a significantly higher proportion of urine, thus keeping it off the paddock to be leached out of the soil in the winter drainage season.

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