Abstract:
We evaluated the impact on performance
of top dressing a based total mixed
ration (TMR) with long-stem alfalfa hay
with or without additional dry-rolled corn
to the lactating cow diet during the first 5
days postpartum. The three dietary treatments
and numbers of cows assigned to
each diet were: 1) total mixed ration
(TMR; n = 19); 2) TMR + long-stem alfalfa
hay (TMR + A; n= 20); and 3) TMR
+ long-stemmed alfalfa hay + dry-rolled
corn (TMR + A + C; n = 20). Top dressing
the lactating TMR with long-stem alfalfa
hay with or without dry-rolled corn did not
reduce the incidence of metabolic disorders
in early lactating cows. Six cows, two
on each diet, were treated for displaced
abomasums. Cows consuming only the
TMR lost slightly more body weight during
the first 30 days after calving compared
to cows fed the other diets. Milk and
energy corrected milk (ECM) yields were
similar among diets. Fat, protein, and urea
nitrogen content in milk were not different
among dietary treatments. Lactose content
in milk was greater for cows consuming
TMR + A than those consuming TMR or
TMR + A + C. Concentrations of glucose
and urea nitrogen in plasma were not affected
by treatment during the initial 5
days of lactation. Concentrations of glucose
and urea nitrogen on days 2 and 3
were less for multiparous cows consuming
TMR than for multiparous cows consuming
TMR + A. Rumen contractions during
the first 5 days of lactation were not different
among diets. Top dressing the lactating
TMR with long-stem alfalfa hay
with or without dry-rolled corn was not
beneficial in this study. On a dry matter
basis, the lactating TMR contained 22%
chopped alfalfa hay, 10% corn silage, 20%
wet corn gluten feed, 9% whole fuzzy cottonseed,
7.1% expeller soybean meal,
27.4% ground shelled corn, 1.2% molasses,
1.3% Menhaden fishmeal, and 2.0%
mineral-vitamin premix. Cows fed diets
containing corn silage as the predominant
fiber source may respond differently.