Milk production in Ireland, New Zealand and Australia is seasonal,
with the
majority of cows calving in spring. This pattern of production makes the
maximum
use of grazed grass, and in Ireland >80% of total milk for manufacturing
is
produced between April and November inclusive. Such a seasonal pattern
of
production results in a large variation in the gross composition of
milk due to stage
of lactation effects (Phelan et al. 1982). Some studies
have investigated the
relationship between milk composition and its processing characteristics
(O'Keeffe et
al. 1982; Grandison et al. 1984); however, in these studies
the effects of diet and
lactation stage were not segregated. Kefford et al. (1995) attempted
to segregate the
effects of diet and stage of lactation and concluded that diet quality
(type and
quantity) had a larger effect on Cheddar cheese quality than
the stage of lactation.
The nutritive value of the diet of cows fed on grazed grass can change
owing to
changes in grass supply or quality. In the current study, changes in
grass supply were
achieved by altering the daily herbage allowance (DHA) to the herds. The
objective
of the current study was to investigate the effect of varying the DHA in
the range
16–24 kg grass dry matter (DM), which is typical of the variation
in pasture
allowance in Ireland in mid lactation, on milk composition and its processing
characteristics.