Utilization of barley grain in substitution of corn in diets for lactation cows

Abstract

In the present research work the effects
of partial and total substitution of ground corn grain by
dry rolled barley on the milk production and composition
were evaluated. Twenty-eight Holstein cows with an
average of 125 days in milk were used in a 4x4 latin
square design. Once a day, the diet was supplied in a
totally mixed ration. Four levels of corn substitution by
barley were tested (T1 0% barley; T2 33% barley;
T3 67% barley; and T4 100% barley. The experiment
was carried out during 105 days. Cows were milked twice
a day and contents of fat, protein, milk total solids, and
somatic cell count (SCC) were established twice in each
treatment period and the milk urea nitrogen (MUN) at
the end of each period. The dry matter intake decreased
in a linear fashion when barley replaced corn in the diet.
However, the ingestion of crude protein, neutral fiber
detergent and acid fiber detergent were not affected
when substituting corn by barley. Linear reduction was
observed in milk yield, fat corrected milk production and
fat and protein contents of the milk, while the protein
percentages increased in a linear way. No effect was
registered concerning the levels of substitution on the
protein production, total solids of the milk, SCC, MUN
and on the conversion efficiency.