Article

Maize meal supply in finishing bull farms: physical and chemical variability

Italian Journal of Animal Science (Impact Factor: 0.72). 04/2010; DOI: 10.4081/ijas.2007.1s.360
Source: DOAJ

ABSTRACT

The work was carried out in 15 associated beef farms with the aim of monitoring animal food quantity and quality starting from the chemical analysis of the components used to formulate the total mixed rations (TMR) for finishing Charolais (CH=9 farms) and Limousin bulls (LI=4). In particular cereal grains, mainly maize, constitute the 25.6% + 6.7 (as fed) of TMR. The samples of maize grains were collected for about three months (N=57) to perform chemical analysis: dry matter, crude protein, ether extract, ash, soluble polysaccharides (SC, by a-amylase treatment) and fibre fractions (a-NDF, ADF, ADL). The a-amylase treatment did not give values of fibrous fractions with a satisfying repeatability and there is not a good accord between SC (100- indigested residue) and calculated non fibrous carbohydrates (NFC) values; presumably because it, alone, is not able to degrade crystalline starch (slowly digestible starch). The performing of a heating pre-treatment, to gelatinize starch, improves amylase effectiveness, but it seems to remove some other analytical components, as protein and/or ash (SC =76.3 vs NFC =73.3).

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360 ITAL.J.ANIM.SCI. VOL. 6 (SUPPL. 1), 360-362, 2007
Maize meal supply in finishing bull farms:
physical and chemical variability
D. Settineri, K. Carbone, M. Iacurto
Istituto Sperimentale per la Zootecnia. Consiglio per la Ricerca e la Sperimentazione
in Agricoltura, Monterotondo, Italy
Corresponding author: Donata Settineri. Istituto Sperimentale per la Zootecnia, Sezione
Alimentazione e Nutrizione. Consiglio per la Ricerca e la Sperimentazione in Agricoltura. Via Salaria
31, 00016 Monterotondo (RM), Italy - Tel. +39 06 90090231 - Fax: +39 06 9061541 - email donatel-
la.settineri@isz.it.
ABSTRACT: The work was carried out in 15 associated beef farms with the aim of monitoring animal food
quantity and quality starting from the chemical analysis of the components used to formulate the total mixed
rations (TMR) for finishing Charolais (CH=9 farms) and Limousin bulls (LI=4). In particular cereal grains, mainly
maize
, constitute the 25.6% +
6.7 (as fed) of TMR. The samples of maize grains were collected for about three
months (N=57) to perform chemical analysis: dry matter, crude protein, ether extract, ash, soluble polysaccharides
(SC, by
α-amylase treatment) and fibre fractions (α-NDF, ADF, ADL). The α-amylase treatment did not give values
of fibrous fractions with a satisfying repeatability and there is not a good accord between SC (100- indigested
residue) and calculated non fibrous carbohydrates (NFC) values; presumably because it, alone, is not able to
degrade crystalline starch (slowly digestible starch). The performing of a heating pre-treatment, to gelatinize
starch, improves amylase effectiveness, but it seems to remove some other analytical components, as protein and/or
ash (SC =76.3
vs NFC =73.3).
Key words: Soluble Carbohydrates, ND-Fibre Analysis.
INTRODUCTION - The final goal of the research-development Project “Evaluation and Standardisation of a
Meat Production System from Rearing to Distribution” was to study the possible variability of meat in a produc-
tion system, which starts with the intensive rearing of finishing beef cattle to arrive at slaughtering and meat dis-
tribution, with the aim to standardize and optimize the final product. To achieve this goal it seemed useful the mon-
itoring of animal food quantity and quality, along a productive cycle, starting from the sampling of diet components
for physical and chemical analysis (Ronchi
et al., 2006; Settineri et al., 2006). The diets for finishing beef cattle are,
usually
, based on maize silage
, concentrates and starch sources to promote high daily gains in order to short, as far
as possible, the feeding time to reach rapidly slaughtering weights. The most important diet energy supply is, maize
grain (
70% of starch); however, its utilisation by rumen micro-flora and its nutritive value for the animal depends
on:
partic
le size (crushed,
milled or flour ground grains) or on physical treatments. Moreover the excessive content
in the diets of readily soluble polysaccharides may lower rumen fluid pH (Ronchi
et al., 2006), alter rumen motili-
ty (Mertens, 1992) and cause some pathological conditions as metabolic acidosis (Sauvant
et al., 1999). The aim of
this methodological approach to maize physical and chemical characteristics was to examine closely feedstuffs real-
ly used in farm practice.
MA
TERIAL
AND METHODS
-
The work w
as carried out in 15 associated beef farms in the eastern P
o val
-
ley;
eac
h farm produces the used maize silages, the other components of the rations, as cereal grains, were bought
with the help of the
Association organisation. Fifty seven samples of maize grains (2 kg; collected every three
weeks for about three months) were classified into 4 particle size classes: I, flour meal (<1mm pore size); II, sand
meal (crystalline grains of
2-4mm, ); III, crushed grains; IV, broken grains. Samples were ground (GS) or not
(rough samples, RS). On both RS and GS were performed the following determinations: soluble substances and car-
bohydrates (SC), as starch, by weighing the residue (dried at 60 °C) of 1.3g +
0.02 samples after a 24h incubation
(40°C) with
α-amylase (from bacillus subtilis,
SIGMA,
8g/l in Na-K phosphate buffer
,
pH 7.0;
SC =100–indigested
residue); neutral-detergent fibre,
α-NDF, after the α-amylase incubation (AOAC, 2002; In Focus, 2005); ADF and
ADL (Van Soest
et al.,
1991).
On GS were also performed standard c
hemical analyses (dry matter, crude protein,
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NAT. CONGR. ASPA, ALGHERO, ITALY
ITAL.J.ANIM.SCI. VOL. 6 (SUPPL. 1), 360-362, 2007 361
ether extract, and ash; AOAC, 1990) and a modified SC determination by introducing a 4h pre-incubation at 94
°C (HGS), followed by
α-amylase digestion and then NDF analysis.
RESULTS AND CONCLUSIONS – The diets were formulated to meet the nutrient requirements of finishing
C
harolais and Limousin bulls (
4
50kg of ILW) for an AMG of about 1,3 kg and were provided as total mixed rations
(TMR); cereal grains, quite exclusively maize, constitute the 25.7% +
7.0 and 25.3% + 5.6 (as fed) of CH and LI TMR
respectively; however maize grains, offered to animals, were extremely variable in particle sizes (Ronchi
et al.,
2006). To have some ideas of the effective food utilisation by rumen micro-flora, and, of course by the animals, it
seemed worthy to quantify the differences which could arise in the maize fibre fraction contents (table 1) performed
on RS: only the I class
α-NDF value resulted, in spite of the very high variability, near to literature data (Martillotti
et al., 1988; In Focus, 2005); ADF and ADL values were lighter influenced by the sample grain sizes but the stan-
dard errors of the determinations increase from the I to the IV maize classes. The differences between RS and GS
were underlined in table 2 and, obviously, GS values were less variable and closer to literature data than RS; how-
ever the
α-amylase treatment did not give values of fibrous fractions with a satisfying repeatability (In Focus, 2005)
and there is not a good accord between SC and calculated NFC values, presumably because the amylase treatment
alone is not able to degrade crystalline starch (slowly digestible starch).
Table 1. maize grain soluble substances and structural carbohydrates determined on
the 4 classes of rough samples (RS): I, flour meal; II, sand meal; III, crushed
grains; IV, broken grains (% on DM; means + SD).
SC
1
α-NDF
2
ADF ADL
R S Classes N means
± SD means ± SD means ± SD means ± SD
I 10 43.5
aA
4.636 18.3
cB
5.072 3.64
cB
0.752 0.76
cB
0.311
II 17 40.8
aAB
6.160 21.4
cB
4.758 3.87
cB
0.771 0.81
abcA
0.416
III 10 34.4
bB
8.233 27.3
bA
5.994 4.04
bA
0.773 1.10
bA
0.319
IV 20
31.8
bB
4.792 34.1
aA
7.608 4.93
aA
1.057 1.85
aA
0.865
All samples
3
57 37.01 7.472
3
26.36 8.771
3
4.23 1.010
3
1.22 0.7523
1
: Soluble substances and
2
: neutral detergent fibre after 24h
α
-amylase incubation;
a, b, c
P< 0.05;
A,B
P< 0.01; N: number of data;
3
: means and RMSE: root mean square error.
Table 2. Chemical analysis, soluble and structural carbohydrates of maize grains (% on
DM).
Rough Samples (57) Ground Samples (57) (104)
means ± SD means ± SD P RMSE
Dry matter 86.30 2.419 86.69 1.664 ns 1.940
Crude Protein —-
—- 9.07 1,110 —- —-
Ether extract —- —- 3.99 0.291 —- —-
Ash 1.55 0.288 1.54 0.238 ns 0.263
S C 37.01 7.472 46.27 5.262 *** 7.940
NFC
1
59.54 8.304 68.57 2.697 *** 7.638
α-NDF
26.36
8.771
17.08
2.692
*** 7.963
ADF 4.23 1.010 3.69 0.735 ** 0.921
ADL 1.22 0.752 1.03 0.332 ** 0.608
Cellulose
2
3.02 0.643 2.85 0.630 ns 0.639
1
: Non Fibrous Carbohydrates: 100 –(CP + EE + Ash + NDF – NDFash);
2
: (ADF-ADL); * P< 0.05; ** P<
0.01; *** P< 0.001; in brackets: number of data; RMSE: root mean square error.
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362 ITAL.J.ANIM.SCI. VOL. 6 (SUPPL. 1), 360-362, 2007
AS the NDF represents the total structural carbohydrates, this treatment should remove most of proteins, the
lipids and portion of mineral content; in fact the pre-heating treatment gives
α-NDF values (table3) in good agree-
ment with literature (Martillotti
et al., 1988), but quite higher value of soluble carbohydrates (SC) in respect to
NFC (76.32
vs 73.26). The average values of the sample portion removed by NDF, which is calculated as difference
f
rom the indigested residue after _-amylase and NDF ((100-SC)-_NDF)), should represent the sum: “CP + EE + Ash
NDFash”, but the found values differ considerably, differences are higher and opposite for GS than for HGS sam-
ples (+60.1%
vs -21.4%). Heating pre-treatment is useful to gelatinize crystalline starch, improving amylase effec-
tiveness (In Focus, 2005), and it gives more repeatable analytical data; however it seems to remove some other ana-
lytical components, as protein and or ash. Probably, RS fibrous fraction values better reflect the effective digestive
utilisation of maize, that depends strictly on the size of ingested grains that were, during the trial, often found
“as fed” in faeces (Ronchi
et al., 2006).
Table 3. Soluble substances and structural carbohydrates of maize grains on ground
samples (GS) and on pre- heating GS (HGS; % on DM).
GS (57) HGS (57) (104)
means ± SD means ± SD P RMSE
S C 46.27 5.262 76.32 2.782 *** 15.660
NFC 68.57 2.697 73.26 3.005 *** 3.691
α-NDF 17.08 2.692 12.44 2.882 *** 3.626
(100-SC)-(
α-NDF) 36.55 4.629 11.25 2.507 *** 13.284
(CP + EE +Ash – NDFash) 14.36 1.248 14.32 1.261 ns 1.249
Notes: see table 1 and 2.
The Research was supported by MiPAF, Project “STANDBEEF”.
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th
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