Parameter Estimation Utilities
The NUTBAL decision support system has several small programs that enable
the user to estimate critical animal and feedstuff attributes.
COWSCORE determines either weight, frame score or body condition
score for cattle, given age, gender, and the other 2 parameters
(for weight, enter frame score and body condition score, for
frame score, enter weight and body condition score etc.)
This program accepts input of calf age, calf weight at the specified age in
days and the frame score of the cow to estimate peak milk. The program was
adapted from Fox et al. (1988). The values are reasonable for calves
greater than 120 days. To overcome this problem another program was
developed for descreet calf age groups.
Peak milk yield is estimate by requesting calf age in discreet age groups of
1,2,3,4,5,6 and 7 months of age. Calf weight for that age and frame score
of the cow are requested then to compute peak milk yield of the cow. This
method has a lower standard error of estimate of peak milk yield. The
method was derived from Fox et al. (1988).
This program requires users to input the cows frame score and peak milk
yield along with age of the calf in question. Calf weight for the specified
age is then computed. Equations were derived from data provided in Fox et
al. (1988).
Because feed tags only provide estimates of crude protein (natural and
urea), fiber, ash, moisture, and in the case of liquid feeds, total inverted
sugars, it is difficult for users to input TDN values of feeds without
requesting TDN values of a particular lot sold to a producer. In many cases
feed representatives cannot or will not provide the information. To
facilitate this process, TDN requests ingredient composition and provides
default digestibility of each component. The user can modify the default
digestibility values to derive an "as fed" TDN value (%) and a dry matter
TDN (%) value. Entries of feedstuff values in NUTBAL are reflected on a dry
matter basis, requiring computation of CP and ASH values on a dry matter
basis from tag values as well.
Because NUTBAL adjust intake based on standing crop of available forage,
there are instances where animals are subjected to high, short duration
grazing pressures where current standing crop rapidly declines. FORAGE is a
utility program designed to help adjust intake for these types of
situations. An intake adjustment factor is computed based on input of
current standing crop, pasture size, animal numbers, average body weight,
expected duration of stay in the pasture, percent harvestable forage,
non-harvestable standing crop,and growth rate of forage. The user sets the
available standing crop to >2300 lb/ac in NUTBAL and then inputs the intake
adjustment factor computed by FORAGE if a negative intake factor is
computed. Typically, stock densities must be less than 5 ac/au and standing
crops less than 2000 lb/ac before negative impacts are noted. After
extensive review of the behavior of NUTBAL's standing crop algorithm, we
suggest setting the value of 2300 lb/ac in the program and running FORAGE if
stocking density is less than 5 ac/au.
Currently, NUTBAL cannot represent negative associative effects of
high-starch grains without first running the GRAIN utility distributed with
NUTBAL. Grain requests from a NUTBAL case without grain represented in the
situation to be analyzed. The body condition score 5 weight and estimated
fecal output from the NUTBAL balance report are input into GRAIN along with
information on the diet quality value of the forage (CP, DOM derived from
NIRS fecal analysis). The amount of grain fed and analysis value for dry
matter (%), ash (%), crude protein (%), and metabolizable energy
concentration (mcal/lb). GRAIN outputs a recommended intake adjustment
factor which actually reduced fecal output of the animal, adjusted DOM value
of the forage on offer and the amount of grain fed expressed as percent of
body weight on an as-fed basis.
Experimental Utilities
Assessment of DIP and DUP Balance in Beef Cattle (Under development
by Scott Schowers)