RESEARCH WORK
Evaluation of the use of fresh or preserved citrus pulp in diets for bull fattening
F. Ojeda1, Bárbara N. Pino2, L. Lamela1, H. Santana1 e I. Montejo1
1Estación Experimental de Pastos y Forrajes"Indio Hatuey"Central España Republicana, CP 44280, Matanzas, Cuba
2 Empresa Citrícola "Victoria de Girón", Matanzas, Cuba
ABSTRACT
With the objective of evaluating the weight gains in bulls that consumed fresh or preserved citrus pulp, a study was conducted for 120 days in two fattening farms of the Citrus Fruit Firm «Victoria de Girón», in Jagüey Grande, Matanzas. Both units had 400 animals and the prevailing breed was commercial Zebu. The management consisted in restricted grazing (four hours) and confinement (20 hours). Pasture availability was 5 and 3 kg DM/animal/day for the rainy and dry seasons, respectively. The diets consisted in green forage and fresh or ensiled citrus pulp ad libitum. In addition, there was supplementation with 0,5; 1,0; 1,1 and 0,05 kg/animal/day of hay, fermented corn residues, wheat bran and mineral salt, respectively; urea was supplied according to feeding balances. Roughage intake and weight gain were measured. Previous feeding balances were made as well as retrospective ones at the end of the study. The highest forage intake (8,1 vs 7,7 kg/animal/day) was obtained in the diet with fresh citrus pulp. The gains were 0,641 vs 0,633 kg/animal/day for the animals that consumed fresh citrus pulp and silage, respectively. The feed conversion was high (11,4 and 11,6 for the animals which were supplied fresh and ensiled citrus pulp, respectively). This evaluation proved that under equal conditions, there were no large productive differences when using any of the two supply forms.
Key words: Citrus, fattening, silage
INTRODUCTION
Livestock production
systems in which the use of citrus fruit pulp in the diet is a priority, face
each year the problem of not having this product when the harvest period ends.
The least convenient
solution is to store as reserve the pulp in its natural status, due to the degradation
processes that occur spontaneously in this product, but especially due to the
contaminating action promoted by its effluents, for which ensiling the surplus
pressed or mixed with hay is proposed (Gohl, 1978).
Ojeda et al. (2008), when evaluating several absorbing materials (sugarcane
bagasse, pre-wilted mulberry and bean straw), proved that it is possible to
obtain silages with adequate nutritional value, in addition to prevent the above-mentioned
negative effects.
The preparation of citrus pulp silages has also the advantage of allowing increases
in the nitrogen contents of the final product, by means of urea incorporation,
because due to its high fermentative potential, although it breaks down to ammonia
this does not interfere the attainment of adequate pH for conservation (Ojeda
et al., 2004).
However, it is important to learn if there are differences in the productive
responses, according to the way in which they are fed (fresh or ensiled), and
until now no studies have been conducted in which both supply forms have been
simultaneously compared. Hence, the objective of this work was to evaluate the
weight gain in bulls consuming fresh or preserved citrus pulp, in two fattening
farms of the Citrus Fruit Firm "Victoria de Girón".
MATERIALS AND METHODS
Location.
The study was conducted in the Citrus Fruit Firm "Victoria de Girón",
in the Livestock Production Farm No. 1, located in Torriente, Jagüey Grande
municipality, Matanzas. Climate
and soil. The area shows annual rainfall
of 1 549 mm, distributed from May to October (rainy season), with 81% rainfall
and the rest from November to April (dry season). Mean annual temperature is
24,7ºC, with maximum temperatures of 35ºC and minimum 19ºC; the
soil is classified as typical, rocky and deep Ferralitic Red (Hernández
et al., 1999).
Animals.
The evaluations were made in two fattening farms, for 120 days, from September
to December. In one of them silage was fed and in the other fresh citrus pulp.
Both had 400 animals, where the commercial Zebu breed prevailed. The average
initial weight of the animals was 262 and 278 kg for the animals that ate silage
and fresh citrus pulp, respectively.
Management
system. A semi-confined system was used with 4h- restricted grazing (from
6 a.m. to 10 a.m.) and 20 h of confinement (from 10:00 a.m. to 6:00 a.m. the
next day).
The farms
had a one-hectare pen for the animals (delimited with stone fences) and a grazing
area of 50 ha, divided into four paddocks, which were subject to stocking rates
between 5 and 8 animals/ha.
Both fattening
farms had a feeding trough space of 0,5 m/animal and a drinking trough with
reserve tanks, permanently supplied by a wind mill.
The facilities
also included two sheds of 260 and 300 m2 and an input storehouse.
Feed distribution
and cleaning of the feeding, drinking troughs and adjacent areas were done when
the animals were grazing.
The forage
and fresh or ensiled citrus pulp were supplied ad libitum, in separate
feeding troughs. The fresh citrus pulp was obtained from the juice factory and
put in the feeding troughs (3 m wide, 5 m long and 1,5 m deep).
The forage
was daily harvested with a SPKZ silo harvester from an area where Pennisetum
purpureum prevailed, with a regrowth age between 70 and 80 days, which was
fertilized with 60 kg N/ha in July.
The hay was
made with a mixture of grasses from areas close to the firm, in rectangular
bales with an average weight of 20 kg, which were gathered immediately and deposited
in a storehouse under roof until its later distribution in the fattening farms.
Feeding.
The prevailing pastures were Dichanthium annulatum and Dichanthium
caricosum, with low average availability (5 and 3 kg DM/animal/day during
the rainy and the dry season, respectively).
The common
diet consisted in green forage and fresh or ensiled citrus pulp, at will, and
a supplementation regulated for both fattening farms, based on grass hay, mineral,
salt, urea and protein complement, supplied in the form of a cake.
This procedure
consisted in placing at the bottom of the feeding trough a layer of hay at a
rate of 0,5 kg/animal, then another of 5 kg of fresh or ensiled citrus pulp
per animal and the urea sprayed when necessary, according to the feeding balance.
On these feedstuffs
1,1 kg of wheat bran, plus 1 kg of fermented corn residues and 0,05 kg of whole
mineral salts was incorporated.
The silages
were made in surface silos, with a proportion of 86% fresh citrus pulp, 10%
grass hay and 4% urea.
The preparation
technology was by layers, using a tractor with a frontal shovel for the introduction
of the roughages and compaction.
The urea
was manually added on the citrus pulp. Once the silo was filled, it was covered
with additional 20-cm-layers of citrus pulp and hay. The fermentation period
of the silage was at least 90 days before being used.
Feed intake.
The diets were recorded in the fattening farms through the control of the daily
entrance of feedstuffs. The intake determination was made through the supply
and rejection method. In order to guarantee that the forage and silage were
supplied at will, they were weighed every week, with the objective of ensuring
that the animals had 10% over the intake. The mineral salt and urea were added
according to the quantities calculated by the previous feeding balances that
were carried out to make the diets, taking into consideration the intake of
roughages and their bromatological composition.
Live weight.
The animals, per group, were weighed on a commercial scale, at the beginning
and the end of the evaluation period.
Bromatological
analysis. Samples were taken from the forage, fresh citrus pulp, silage
and hay, once a month, for determining the dry matter (DM), crude protein (CP)
and crude fiber (CF), by the analytical techniques of the AOAC (1991); while
the metabolizable energy of the feedstuffs was estimated from the chemical composition
tables that appear in the CALRAC program (1996) version 1.0, elaborated by the
Institute of Animal Science (ICA). The bromatological composition of the feedstuffs
used is shown in table 1.
Feeding balance.
Feeding balances were made every two weeks to adjust the forage and silage supplies
during the evaluation period, as well as retrospective balances at the end of
the study by means of the CALRAC program (1991).
Conversion
rate. To compare the efficiency of the diets the feeding conversion value
was determined, dividing the total consumed dry matter between the daily live
weight gain.
Data analysis.
The forage, fresh citrus pulp and preserved citrus pulp intake, as well as the
initial and final weight, were analyzed through descriptive statistics (mean
and standard deviation), using the statistical pack SPSS, in its version 10.0
for Windows.
RESULTS
AND DISCUSSION
The diet
with fresh citrus pulp showed higher forage intake with regards to the diet
with silage (table 2). This increase can be ascribed to the differences between
both feedstuffs regarding dry matter and crude fiber, because fresh citrus pulp
shows the lowest values due to the fact that silage includes 10% hay in its
composition.
Macedo et al.
(2007) consider that when mixed diets are used, the animals intuitively autoregulate
the consumption of the feedstuffs which are supplied ad libitum, in which
their capacity and the need of more adequate ruminal fermentation, according
to their nutritional requirements and productive potential, are combined.
For such reasons,
in this type of diet the protein supplementation is essential, not only to increase
live weight gain, but also to achieve higher intake of fibrous components, because
when ruminal microorganisms do not have enough nitrogen, restrictions occur
in intake up to 23% (Arthington, 2009).
If protein
supplementation is provided as a cake, optimum and homogeneous utilization is
guaranteed, because thus the competition and dominant action among the animals,
which always occur when it is directly distributed in the feeding troughs, are
decreased.
In addition,
its ingestion, combined with fibrous (hay) and easily fermentable (citrus pulp)
feedstuffs leads to spaced intake and induces a positive effect on ruminal microorganisms,
which allows a more efficient ingestion and a more stable ruminal nitrogen-energy
balance (Dolberg and Finlayson, 1995).
In this sense,
the combination of feedstuffs with different nitrogen and energy sources is
also considered a favorable action to achieve better productive responses (Weatherup
and McLauchlan, 2006).
This principle
was achieved with the protein supplementation used, because wheat bran is considered
a supplier of protein, but especially of little-rumen-soluble starches (Peruchena
and D'Ascanio, 1996; Fenzo, 2006);while fermented corn residues, although contributing
energy, also supplied easily-fermentable nitrogen and bypass protein (Salvador,
2007). No
differences were found in the gain, which was 0,641 and 0,633 kg/animal/day
for the animals that ate fresh citrus pulp and silage, respectively. Similar
performance was observed in the conversion value.
The feeding
balances suggest that the diets covered the requirements, according to the weight
and gain of the animals, although in order to maintain the nutrient balance,
due to the differences in protein composition, it was necessary to use urea
in the diet with fresh citrus pulp; while in the diet with silage the bulls
consumed excess protein (tables 3 and 4).
When silage is
supplied the addition of some feedstuff that contributes easy-fermentation carbohydrates,
such as molasses, can be necessary, in order to better utilize its nutritional
potential (Ojeda et al., 2006).
The analysis
of the percentage contributions of nutrients, according to the ingested feedstuff,
indicates that the silage and fresh citrus pulp were the feedstuffs that contributed
the most in dry matter, crude protein and energy; while protein supplementation
was maintained in very similar values (table 5).
The similarities
in the percentage contribution of DM, obtained when adding the combination of
forage plus fresh citrus pulp and forage plus silage should be stated, results
that are interpreted as the response of animals to the intake capacity of these
feedstuffs, which were fed ad libitum in both diets.
Similarly,
the DM contribution of protein supplementation was below 30%, value considered
as limit for the absence of substitution effects in roughages (Peruchena, 2007).
In beef production,
one of the most important indicators and which is adopted as reference criterion
to evaluate diet effectiveness is feed conversion due to its direct relation
to productive costs (Parnell, 1996).
Under tropical
conditions it has been proven that the conversion value in a diet based on Bermuda
grass hay (51,37) can be improved through supplementation. When fish meal is
used it can decrease to 11,05, with cotton cake to 9,92 and an optimum response
of 7,49 can be obtained with brewery wort (Obispo et al., 2001). However,
the responses of feed conversion to protein supplementation are not lineal.
In this sense,
the studies conducted with increasing percentages of supplementation with poultry
dung (15, 25 and 35% of the total dry matter intake) showed favorable changes
in conversion (8,06; 7,35 and 7,86) until the intermediate percentage and a
decrease from it (Duarte et al., 1996).
The feed
conversion found in this study was high (11,6 and 11,4 for the diets with silage
and fresh citrus pulp, respectively), which indicates poor feeding efficiency,
with a slight advantage when fresh citrus pulp was used (table 6).
These values were
better than the ones found by Ojeda et al. (2010) in integral diets,
in which forage and fresh citrus pulp were used as roughage, with values that
varied between 14,0 and 16,3, in addition to obtaining lower weight gains (0,370
and 0,450 kg/animal/day).
The differences
could be linked to the breed component of the animals, because the differentiated
results are from a backcrossing of F1 (Holstein x Zebu) with Zebu, F2.
In this evaluation
it was proven that under equal conditions regarding supplementation, animal
breed, way of supplying the protein supplementation and even the evaluation
period, there were no large differences when using fresh or ensiled citrus pulp.