The use of LIPE® as an external indicator to measure the mobilization coefficient of nutrients and energy values for broilers

Research studies on the chemicostructural composition and physicochemical properties of lignin have been performed by the paper industry in an attempt to remove it as a contaminant of cellulose (Vasconcellos, 2004).

Saliba et al. (2003) isolated then enriched lignin with phenol groups not commonly found in animal dietary lignin. This research yielded a modified, enriched hydroxy-phenyl-propane chemical called LIPE^®, an external digestibility indicator specifically developed for research purposes. LIPE^® was first used in nutrient intake and digestibility studies in rabbits, as compared to the total feces collection technique. Digestibility and fecal production estimates revealed the efficacy of LIPE^® as an external indicator, with no statistically-significant difference with the total collection technique. In addition, further benefits were found in terms of its short adaptation period and low cost. The adaptation period to obtain a uniform excretion is 48 hours. The experimental period for fecal collection is satisfactory (3 collection days for poultry, and up to 5 days for other species). Infrared spectroscopy is the analytical technique used to determine the presence of LIPE^® in the feces. This methodology is rapid, sensitive, inexpensive and, in addition, it does not destroy the sample (Rodrigues et al., 2007).

In order to evaluate the reliability of an indicator, digestibility assays must be performed comparing the results obtained with the indicator in question with those from the total feces collection technique. The purpose of this study was to evaluate the efficacy of LIPE^® as an external indicator to measure the digestibility coefficient of nutrients and energy values, as compared to the total feces collection method for broilers in the growing phase.

The digestibility of nutrients was measured using LIPE^® in the Animal Metabolism Laboratory, Veterinary School, Federal Minas Gerais University, Brazil, using birds from 30 to 33 days of age. Groups of ten male, 22-day-old, Ross broilers weighing 1.038 ± 0.030 kg, were housed in each of 30 experimental units, for a total of 300 birds.

The dietary incorporation of LIPE^® allows for measuring feed intake and fecal production.

The amount of feed offered and feed left overs were weighed at the beginning and at the end of the experimental period, respectively. Excreta were collected twice a day during the 4-day excreta collection period.

LIPE^® was first diluted in acetone then incorporated by spray as a top dressing on each treatment ration, then homogenized. Feeds were set aside for a 24 hour period, for evaporation purposes, prior to being offered to the animals. The inclusion level was 0.1 g LIPE^®/kg of feed. One thousand (1,000) g feed were offered per day, for 5 days (2 days for adaptation; 3 days for collection). The LIPE^®-treated ration was given in the morning, after removing feed leftovers from the previous day. The remainder of the daily ration (calculated by the daily intake in the group, in accordance with the Ross manual) was given in the afternoon.

The materials collected were conditioned in plastic bags, weighed and stored in the freezer until the end of the collection period. Afterwards, excreta were weighed and placed into a forced ventilation incubator at 60ºC for 72 hours (pre-dry). These materials were then exposed for 3 hours at ambient temperature, weighed and homogenized. A sample was then taken to determine dry matter, ether extract and nitrogen contents. The experimental rations were also analyzed for dry matter, ether extract and nitrogen, following the techniques described in the Brazilian Animal Nutrition Compendium (Compêndio Brasileiro de Nutrição Animal) (2005). Dry matter and nitrogen analyses were performed in the Nutrition Laboratory, Veterinary School, UFMG, Brazil. Ether extract analyses were performed in the Physicochemical Analysis Laboratory, Department of Technology and Inspection of Animal-Origin Products, Veterinary School, UFMG, Brazil.

The technique used to analyze lipid contents in the feces was Fourrier-transformed infrared spectroscopy.

Fecal production was determined using an external indicator by the following equation:

(Translator's Notice: Equations as is in the original Portuguese language document are followed by their literal translations herein):

or:

Where: RR = indicator recovery rate, estimated as follows:

or

Using the laboratory analytical results together with feed intake and fecal production data predicted by the LIPE^® analysis, dry mater apparent digestibility coefficient (DMDC), crude protein digestibility coefficient (CPDC) and ether extract digestibility coefficient (EEDC), were calculated using the following equation:

 

or:

 

In order to compare both nutrient digestibility determination methods (total collection vs. LIPE^®), a random blocks experimental design was used, including two treatments with 24, 10-bird repetitions. Each repetition was a block. Pearson's correlation  between the response after applying both digestibility determination methods was determined. Data was statistically analyzed using the SAEG software (2007).

The correlation values between both digestibility determination methods (LIPE^® vs. total feces collection) for the responses studied are shown in Table 1.

Table 1. Pearson's correlation (%) between dry matter digestibility coefficient (DMDC), crude protein digestibility coefficient (CPDC), ether extract digestibility coefficient (EEDC), apparent metabolizable energy (AME) and nitrogen balance-corrected apparent metabolizable energy (AMEn), determined by both the total feces collection method and the purified eucalyptus lignin (LIPE^®) method

For the DMDC, no correlation was observed between both methodologies, even though DMDC results were numerically similar. For all other variables, strong (>70%), significantly positive (P≤0.01) correlations were found. This was due to the similarity of results, even with the statistical differences found between both methods.

When both methodologies were considered as treatments, and after a comparison by the F test, no differences (P>0.05) were found among them, as shown in Table 2.

Table 2. Dry matter digestibility coefficient (DMDC), crude protein digestibility coefficient (CPDC), ether extract digestibility coefficient (EEDC), apparent metabolizable energy (AME) and nitrogen balance-corrected apparent metabolizable energy (AMEn), determined with both methodologies

In Table 2, using LIPE^® to determine the nutrient digestibility coefficient and energy for broilers in the growing phase showed similar results when compared to those from the total excreta collection methodology. This result is similar to that reported by Vasconcellos et al. (2007.)

As an external indicator, LIPE^® can be used to measure fecal production then subsequently determine digestibility coefficients and energy values for growing broilers.

Brasil. Ministério da Agricultura e Abastecimento. Sindicato Nacional da Indústria de Alimentação Animal. Associação Nacional dos Fabricantes de Rações. 2005. Compêndio brasileiro de nutrição animal. São Paulo: ANFAR/CBNA/SDR.

Rodrigues PB, Brito JAG, Silva EL, Nascimento GAJ. 2007. Manejo da dieta para reduzir o impacto ambiental da excreção de nutrientes na avicultura. In: VII Seminário de Aves e Suínos, 2007, Belo Horizonte. Anais. Belo Horizonte: AVISUI Regiões.

Saliba EOS, Pereira RAN, Ferreira, WM. 2003. Lignin from Eucalyptus Grandis as indicator for rabbits in digestibility trials. Tropical and Subtropical Agroecosystems 3:1-3.

Universidade Federal De Viçosa - UFV. 2007. SAEG - Sistemas de análises estatísticas e genéticas. Versão 9.1. Viçosa/MG.

Vasconcellos CHF. 2004. Lignina purificada e modificada (LIPE^®), óxido crômico e coleta total de excretas, como métodos de determinação da digestibilidade em frangos de corte. Belo Horizonte: Escola de Veterinária da UFMG. 46p. Dissertação (Mestrado em Zootecnia).

Vasconcellos CHF, Veloso JAF, Saliba EOS, Baião NC, Lara LJC. 2007. Uso da LIPE^® como indicador externa na determinação da energia metabolizável de alimentos em frangos de corte. Arquivo Brasileiro de Medicina Veterinária e Zootecnia 59(2):459-465.