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.