Energy evaluation of fresh grass in the diets of lactating dairy cows
2002
Bruinenberg, M.H. | Zom, R.L.G. | Valk, H.
The discrepancy between the estimated feeding value of fresh grass and the output per kg grass in terms of milk and maintenance was studied by evaluating 12 experiments with grass-fed dairy cows. The percentage grass in the diets varied between 40 and 90. Intake and milk production were recorded daily. Per treatment a number of parameters relating to the composition of the grass, characteristics of the animals, and composition of the total diet were determined. The correlation between each of these parameters and the measured discrepancy was calculated. The digestible organic matter in the grass (DOM), intake of grass, intestinal digestible protein in the total diet, percentage milk protein and body weight gain correlated well with the discrepancy. It was concluded that energy input from grass and energy output in milk production were significantly different (P < 0.05). For the diets with 80–90␐rass a high DOM increased discrepancy. It was furthermore concluded that the maintenance requirements of lactating dairy cows fed grass-based diets are probably higher than the currently used values This was ascribed to energy requirements in the gastro-intestinal tract and to nitrogen excretion
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