Early research conducted by FutureDairy suggests it may be possible to adjust cows' diet in automatic milking systems (AMS) to encourage more cows to be milked between midnight and 6am.
FutureDairy project leader Associate Professor Kendra Kerrisk said this could appeal to dairyfarmers with AMS using voluntary cow movement with robots operating at close to capacity.
"Voluntary cow movement involves cows walking on their own accord to and from the dairy," she said. "In grazing-based AMS, there is usually a lull in milkings between midnight and 6am, a time when cows are naturally less active.
"This doesn't tend to be an issue unless the herd size is close to the capacity of the robots. In that situation, each robot will be able to milk more cows in a given 24-hour period if more cows can be encouraged to visit the dairy during the overnight lull period. Robot utilisation is greatest when there is an even distribution of milkings throughout the day and night."
In grazing-based AMS, the trigger for cows to move around the farm tends to be seeking a fresh or new feed source.
AMS farmers can encourage cow movement by adjusting the timing and proportion of each allocation.
"The cows are always fully fed, but the daily allocation is split into three ù or sometimes more ù meals," she said.
FutureDairy researcher, Alex John, investigated the impact of two possible ways to adjust the feeding routine to encourage overnight milking:
Offering a 'preferred' feed between midnight and 6am.
Varying the amount of feed offered in the early evening.
His first trials compared cow preference for either high-protein or high-carbohydrate feed. "Cows showed a very strong preference for the high-carbohydrate feed," Mr John said. "We found that by offering a high-carbohydrate feed between midnight and 6am, we were able to increase the proportion of total daily feed intake during that six-hour period by an additional 50 per cent."
He also looked at the effect of offering more feed at night. "In dairy cattle, grazing tends to peak at dawn and dusk so we wanted to see what would happen if we offered feed timed at the opposite of their normal feeding behaviour," Mr John said.
"Offering more feed between midnight and 6am resulted in nearly two-and-a-half times the feed intake during this time. There was a small decrease in daily dry matter intake, however, this would likely be offset by an increase in overall farm efficiency," he said.
While both approaches worked, there was no additional benefit by combining the two (such as offering a larger allocation of high-carb diet from midnight).
Mr John concluded that varying the amount of feed offered at night offered the most potential to increase robot utilisation. "This is a relatively simple practice that can easily be adapted into current pasture-based AMS practices," he said. "It is an approach that is already used on several Australian AMS farms."
Currently, the timing and size of portions varies across farms but Mr John's results showed the greatest increase in feeding activity between midnight and 6am was achieved by reducing the amount of feed offered in the evening (between dusk and midnight) and increasing the amount of feed offered between midnight and 6am.
"However, we need to recognise there is a limit to the amount of activity that can be encouraged in the natural rest period between midnight and 6am," Mr John said.
"Based on results to date we'd suggest no more than 35 per cent of the total daily ration be allocated between midnight and 6am."
Mr John is conducting further trials at the research AMS farm at the University of Melbourne's Dookie campus to validate his findings in a working automatic milking system.D
Contact: FutureDairy Associate Professor Kendra Kerrisk, phone 0428 101 372, email email@example.com.
FutureDairy's major sponsors are Dairy Australia, DeLaval and the University of Sydney.