Feeding Systems with Legumes to Intensify Dairy Farms - cgiar

The model predicts expected milk yield from three different sources:
from metabolizable energy (ME), from protein (P), and from amino acids
availability (AA). However, the discussion will be centered on the results
obtained from the first two sources because there was no information on the
AA composition of the forages obtained from Quilichao nor was information
available from the tropical forages library.
Table 2. Consumption of sugarcane and Cratylia and predicted intake of
Brachiaria decumbens for the different trials at Quilichao,
Colombia.
Triala Sugarcane Cratylia Brachiaria Total DM
decumbens
(% LW)
ISR + sugarcane 4.43 0 5.04 9.47 2.12
ISR + 75% sugarcane + 25%
legume
2.64 1.16 5.81 9.61 2.15
ISR + 50% sugarcane + 50%
legume
1.48 2.28 5.83 9.59 2.15
ISR + 25% sugarcane + 75%
legume
0.45 4.16 5.03 9.64 2.16
LSR + sugarcane 2.00 0 7.48 9.48 2.30
LSR + sugarcane + legume 2.92 0.62 6.02 9.56 2.32
HSR + sugarcane 2.00 0 6.96 8.96 2.17
HSR + sugarcane + legume 2.92 0.70 5.60 9.22 2.24
a. ISR = intermediate stocking rate; LSR = low stocking rate; and HSR = high stocking rate.
As can be observed, the CNCPS model predicted the observed milk
yields in both the low and high stocking rate trials, but failed to predict the
observed milk yields for the intermediate stocking rate trials. This
underprediction came from both the energy and protein portions, but the
bias was larger in predicting milk yields using the protein portion.
The probable cause of the low prediction of milk yields for the
intermediate stocking rate using the protein portion is the indigestible dry
matter which causes low microbial growth, due to high levels of NDF from
both B. decumbens (69%-70%) and C. argentea (63%-66%). Based on Dr.
Alice Pell’s comments, the high lignin content found in Cratylia could be the
reason why the CNCPS model underpredicted observed milk yield. Based on
Pell’s experience, lignin content of Cratylia leaves and stems should have
been around 7%-8% but not the 16%-17% as found in the Quilichao work.
The secondary compounds may be confounded with lignin, masking the
overall effect of diet.
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