As Straw Intakes Goes up, Gains Go Down
Among 8 Week-Old Hiefers
In a research trial (Hill, T. M. and Others, "Roughage amount, source, and processing for diets fed to weaned dairy calves." The Professional Animal Scientist 26:181-187 2010) that ran for 56 days weaned Holstein calves from a single dairy were fed a 21% c.p. textured grower feed and 0, 3, 6, or 9% chopped wheat straw blended in by hand at the time of feeding.
The average daily gains 8 to 16 week-old heifers over the 56-day trial by straw feeding rate were:
Chopped straw % Ave.Daily Gain
0 2.8 1.27
3 2.4 1.10
6 2.1 0.96
9 2.0 0.89
Other growth measures were Hip Width, Body Score; they also declined as straw intake increased.
In contrast, when grass and alfalfa hay were fed at low levels (3%) average daily gains increased.
As feeding rates of these forages continued to increase beyond 3 percent, however, rates of gain tapered off.