Data di Pubblicazione:
2009
Citazione:
Sorghum forage as an alternative to corn silage in dairy cows feeding / S. Colombini, G. Galassi, G.M. Crovetto, L. Rapetti. ((Intervento presentato al convegno Joint Annual Meeting ADSA-ASAS tenutosi a Montreal, Canada nel 2009.
Abstract:
Aim of the study was to study the possibility of substituting corn silage
with low lignin (brown midrib, BMR)-sorghum silage in the diet of
lactating cows. Two TMRs containing BMR333 single harvest sorghum
forage silage (SF) or corn silage (CS) were fed to 60 Holstein dairy cows
in a change-over design. Diets included (dry basis) 26.3% CS or 17.3%
SF, 6.0% alfalfa hay, 11.0% Italian ryegrass hay and 56.6% or 65.7%
concentrate for CS or SF diet, respectively. Diets had 15.5% CP, 31.5%
aNDFom and 24.2% starch, on DM. Due to the low SF starch content
(2.8% on DM), a higher amount of corn meal was included in the SF
diet (5.7 vs 8.0 kg/d). Forages were also incubated in situ to determine
rumen degradability and degradation rate (kd) of NDF. All data were
statistically analyzed by SAS-GLM procedure. DMI was not affected
by diet (24.4 vs 25.4 kg/d for CS and SF fed cows). Milk yield (32.6
and 33.1 kg/d for CS and SF diets), milk fat (4.16% for both diets) and
milk protein (3.42 and 3.40% for CS and SF diets) were not affected by
dietary treatment (NS). MUN was lower in the diet CS (9.2 vs9.9 mg/dl;
P<0.001); this was probably due to the higher starch fermentability of
corn silage as compared to corn meal, included at a higher proportion
in the SF diet, resulting in a better N utilization for CS diet. The rate of
aNDFom degradability (kd) was higher for SF, although only a trend was
detected. On the other hand potentially degradable aNDFom (a+b) was
higher for CS; thus, effective degradability was not different between
the two forages (table 1), confirming the results obtained in vivo. BMR
sorghum silage can be effectively used in dairy cow feeding, provided
starch content of the diet is balanced.
Table 1. In situ rumen DM and aNDFom degradability
DM aNDFom
CS SF SE P CS SF SE P
a1 (%) 33.1 23.7 0.44 *** 3.63 3.27 1.08 NS
b2 (%) 46.3 48.7 0.23 ** 67.3 63.3 1.55 NS
kd (%/ h) 3.3 3.3 0.19 NS 2.5 3.10 0.17 0.07
a+b3 (%) 79.4 72.4 0.39 *** 70.9 66.6 0.71 *
Effective deg4 49.5 40.8 0.73 ** 21.5 21.8 1.11 NS
*P<0.05; ** P<0.01; *** P<0.001. 1soluble fraction; 2degradable fraction;
3 potentially degradable fraction; 4effective degradability with a passage
rate of 6%/h
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Keywords:
sorghum forage BMR ; dairy cow ; NDF degradability
Elenco autori:
S. Colombini, G. Galassi, G.M. Crovetto, L. Rapetti
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