Instigator of the exercise, animal nutritionist Dr Simone Hoskin said it was a good way of highlighting the difficulty of visually assessing the feeding value of crops and conserved supplements.
“No one got it right and I think that justifies why you should get feed tested,” she said.
Although farmers generally had a good handle on what a quality pasture looked like they often struggled once it was made into fermented staples such as silage and balage.
“There are a huge number of variables that come into play when and once it’s made so I strongly recommend that any fermented feed that’s going to be fed in quantity is tested.
"It helps understand where the limitations are and how it could restrict productivity and ultimately profitability.”
The biggest limiting factor was metabolisable energy (ME), related to digestibility, and then protein for growing stock.
However, once the levels of each were known a performance target and feeding plan could be figured in to a feeding plan that was target based.
“It’s all about the old saying of ‘measuring to manage’,” Hoskin said.
But the important thing was to plan and test in advance so there was time to fill any nutritional deficit. Winter crops, especially brassicas such as kale and swedes should be tested because of their huge year-to-year variation in ME and protein levels.
ME levels could vary from eight to 12 over two consecutive years making potential for a serious mismatch between estimated and actual feeding levels required.
Also with silage, measurement of pH, ammonium nitrate and lactic acid levels were important because they indicated how good fermentation had been.
Hoskin recommended that farmers pay for any bought-in supplement on a cents/ megajoule (MJ)/kg ME rather than a quantity-based c/kg/drymatter (DM).
Hoskin is well-versed in feed quality with her scientific career focused on forage nutrition from field agronomy and the study of feeding values to experiments into forage preference, digestibility and nutrient metabolism.
The former Massey University senior lecturer and AgResearch group leader is now the Deer Industry New Zealand Advance Party facilitator of the Hawke’s Bay Fast Finishers group, scientific adviser for Fiber Fresh Feeds and also finishes weaner deer and cattle on 88ha near Palmerston North.
This year’s 90 weaners – half the number of what was planned because of an overly wet early winter – grazed Relish red clover or plantain mixes from weaning in late February until mid-May, achieving a daily growth average of 285g.
They’ll graze mostly new Ohau ryegrass-based mixes until spring when they’ll be rotated around the herb and legume-based pastures and drafted for the spring chilled season.
“Even on a bad day I know it’s got an ME of 11.5-12% and a protein level of 20%-plus.”
Energy and growth
As a general guideline every unit increase in ME increases a weaner deer’s daily growth by 50g. According to Deer Hub at deernz.org.nz the ME required for maintenance is typically 8-9 MJ/kg DM.
For moderate growth or during lactation a diet providing 10.5-12 MJ/kg DM is needed and for high growth, above 12 MJ/kg DM.
The recommended crude protein levels, expressed as grams/kg are 10-12% for maintenance, 14-16% for growth, 16- 18% for lactation or velvet growth and 18-20% for spike initiation.
Another online tool on Deer Hub – the DEERFeed calculator at intake.deerfeed.co.nz – uses the hind weight and the calf weaning weight and days to weaning to calculate the total feed requirements in MJME/day and kg DM/day.
Feed quality testing – what it costs
Hill Laboratories is the main provider of feed quality testing in New Zealand. Testing of fresh feed and forage is $69 (plus GST) per sample and for silage $79 (plus GST).
The silage sample supplied must have been stacked for at least two weeks.
“This gives the farmer information to assess against the feed requirements for the stock, especially when the pasture is being supplemented with other feed types,” Hill Laboratories agriculture client services manager, Janice Christiansen, said.
A more detailed analysis that would include additional tests for trace elements costs $149 (plus GST) per sample.
This type of test was worthwhile when stock were likely to be exposed to stress such as during calving, lambing and lactation.
If the feed is to be used as a winter supplement a single test should be sufficient. But crops grown onfarm could be sample tested for minerals at mid-growth stage to check for any mineral deficiencies that could hamper animal growth rates.
Results of tests were usually with farmers within a week of testing.
For more information on feed, crop or silage testing go to hill-laboratories.com – free do-it-yourself sampling kits are also available.
Testing for forages and supplements for feed quality gives farmers more certainty in feeding decisions to maximise production.
