Science coming second in water decisions
Emotions and values now come first in water quality assessment and science comes second, says a water quality specialist with DairyNZ, Tom Stephens.
Results and information from the project will be available to farmers mid-2015.
According to DairyNZ, individual cow feeding in New Zealand is based on the idea that some cows can eat more supplement with less effect on the amount of pasture they consume. These cows will therefore have a greater response to the supplements fed - either through increased production or body condition score (BCS).
While individual cow feeding is often used overseas, little is known of its value in pasture-based systems such as in New Zealand where high pasture use is a key driver of profitability.
Individual cow feeding is increasing as more New Zealand farmers invest in in-shed feeding systems. A DairyNZ technology-use survey in 2013 found a third of all farm dairies have in-shed feeding systems installed, with 62% of these rotary and 22% herringbone.
Most of these systems feed all cows the same amount (flat-rate feeding), whereas nearly a quarter can feed individual amounts (individual or differential feeding) according to rules set by the farmer.
The project initially surveyed New Zealand farmers and farm advisors to gain insight into current on-farm practices. The individual cow (or group) feeding strategies most commonly used by New Zealand farmers were: feeding to milk production (58%), breed or age (50%), liveweight (42%), stage of pregnancy (40%) and BCS (37%).
Farmers reported there were benefits in individual cow feeding but there was a lack of clarity around the most profitable feeding strategies.
Simulation modelling was also used to explore common criteria for individually feeding cows (milk production, age, genetic merit, liveweight and BCS) and determine any difference in the milksolids response compared with flat-rate feeding.
The same total amount of supplement was fed in each scenario and results from this modelling indicated there was no benefit to individual feeding.
The final stage of the project was a field study carried out this spring to compare flat-rate feeding with individual cow feeding.
Four herds of 18 cows were flat-rate fed 4kg DM of supplement/cow/day. Another four herds were individually fed according to their milk production ranking. The highest producing cows received 6kg DM supplement/day, the middle cows received 4kg DM/day and the lowest producers received 2kg DM/day. All herds were offered the same total amount of supplement and were managed identically on pasture.
Fast Facts
- One-third of New Zealand dairy sheds have in-shed feeding capability.
- About a quarter of in-shed systems are computer controlled for individual cow feeding.
- There is no robust data to indicate the value of individual cow feeding in New Zealand.
