Valuing Megajoules
A technical report by Dr Roy Fawcett, Bioparametrics
In the Bioparparmetric system ME is not an input it is an outcome from the fermentation of the DM intake.The number we publish on forage reports is from gas production at a set number of hours agreed by a group of expert nutritionists in commercial practice feeding lactating dairy cows
Many of our clients selling raw materials or additives want answers on raw material valuation in use. Clients wish to show farmers that they are getting value for money above the price paid per kg in competition with other raw material sources or additives.
Example from the world of silage additives where enzyme technology can have a big effect.
Our forage analysis shows that better silage has greater fermentability and shorter lag times 3.5 hours compared with ordinary silages fermenting at (0.06)/hr and lag times 4.5 hours or more.
In this example we have a good silage 25% DM 10.7MJ/kg DM and even better silage at 28.6% DM 13.0 MJ/kg DM There is much greater gas production from the 13ME silage directly related to the speed and efficiency of microbial fermentation.
Good silage has the edge on NDF fermentation rate (0.11)/hr as against 0.09/hr and more CP 16.1% .cf CP15.8%
The difference lies in the fermentability of the NDF fraction and the lag times. Fermentability of the NDF fraction is critical
There is slightly more sugar and a difference in the speed of fermentation of other QCHO.
What can be fermented during the residence time in the gut determines the outcome in terms of ME.
|
DM 25 |
ME 10.7 |
CP 16.1 |
SUG 2.2 |
OQCHO 13.2 |
rate/hr 0.09 |
fNDF 28.1 |
Rate/hr 0.11 |
Lag hrs 4.2 |
Good silage |
|
DM 28.6 |
ME 13.0 |
CP 15.8 |
SUG 3.3 |
OQCHO 9.7 |
rate/hr 0.30 |
fNDF 41.5 |
Rate/hr 0.09 |
Lag hrs 3.6 |
Better silage |
A high yielding herd aspiring to 11,500 litres in 305 days needs cows peaking at 50 litres per day
A Good Grass silage 10.7ME and 16.1%CP is usually fed with maize silage ME 11.3 and CP% 8.5
A balanced TMR averaging 11.8 MJ/kg 16.9% CP will supply 324 MJ per day and 2668g MP per at a dry matter intake of 27.5 kg/day. Yield49.1 litres[ 56% ForageDM], [conc DM 0.24 kg/litre] [all feed cost 8.9ppl]
With better grass silage 13 MJ/kg 15.8% CP we can provide higher energy density diets. For example TMR. 12.6 MJ/kg DM and 16.9% CP supplying 362MJ per day and 2820g MP per day at a dry matter intake of 28.8Kg cows reach 51.1 litres per day [60% ForageDM], [conc DM 0.23 kg/litre] [all feed cost 8.2 ppl]
Benefit occurs from more forage dry matter in the TMR since forage DM is cheaper than concentrate DM
Increased energy density in the silage is 13-10.7 = +2.3 MJ/kg DM
So for these cows increased milk production 51.1-49.1 =+2 litres at a cost of 8.2 ppl valued at 24p per litre = 31.6 ppcd (pence per cow day)
Cost reduction on 49.1 litres x 0.7 ppl =34.51 ppcd
Total benefit =£0.6611/ cow day.
Let us restrict this to 1month around peak lactation the benefit is at least £ 19.83 cow month.
So the value of 1 extra mega joule will be £8.6 per cow month. Scale it up to the size of the milking herd.
The text book says that ME requirement for milk is 4.7 MJ per litre at 4% fat , 3.3% protein and 4.6% lactose with a high quality diet q=0.7.
Milk valued at 24 pence per litre requiring 4.7 MJ puts the value of the Mega joules at 4.34pence.
Introducing Optimization into the Biopara-Milk software.
Neil Jessop has designed a facility to export the specification of a high performance diet. This specification provides the profile of the individual dietary components including their fermentation rates so the non forage component can be reformulated at a least cost.
Mega-joules of ME do not feature in this system as exchangeable units of energy. A predicted ME is output from the system as a consequence of utilization expressing animal performance
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