Protein digestibility, performance and carcass quality of broiler chickens fed diets supplemented with centrifuged rumen contents

Sugiarto Achmanu*, D Rosyidi* and A Hasanuddin**

Faculty of Animal Husbandry and Fishery, University of Tadulako, Palu, Indonesia and
Brawijaya University, Malang, Indonesia.
sugiarto.tht@gmail.com
* Faculty of Animal Husbandry, Brawijaya University, Malang, Indonesia
** Faculty of Animal Husbandry and Fishery, University of Tadulako, Palu, Indonesia

Abstract

Two experiments were conducted to evaluate the quality of centrifuged rumen fill of cattle in broiler diets. The first experiment was conducted to investigate the nutritional profile of centrifuged rumen fill and its effect on protein digestibility and apparent metabolizable energy corrected for nitrogen (AMEn) of the diet with different levels of centrifuged rumen fill (CRC). A total of 100 three weeks old-male broiler chickens were used and kept in the metabolism cages for two weeks. The experimental diets were RC0: control diet; RC1: control diet + 1% centrifuged rumen fill; RC2: control diet + 2% centrifuged rumen fill; RC3: control diet + 3% centrifuged rumen fill; RC4: control diet + 4% centrifuged rumen fill. Fecal discharges were collected for three concecutive days from 15 experimental cages. The feeds were offered ad-libitum and water was available at all times. Proximate and fibre fractions (lignin, neutral detergent fibre and acid detergent fibre) of the CRC were determined. Parameters measured were protein and metabolizable energy of the feed. In the second experiment, a total of one hundred male broiler chicks were used. The birds were kept for 42 days and fed the same experimental diets as in experiment 1. The diets and water were offered ad-libitum. A completely randomised design was applied in these two studies with 5 experimental diets and 3 replicate cages in experiment 1, and 5 experimental diets with 4 replicate cages in experiment 2.

Protein content and gross energy in the diets were increased due to addtion of centrifuged rumen fill in the diet. The birds fed the diets containing centrifuged rumen fill had higher protein digestibility, AMEn, body weight gain and breast meat percentage. Feed conversion ratio was better in birds fed the diets supplemented with centrifuged rumen fill.

Keywords: birds, cattle slaughter, nutritive value, vitamins

Introduction

The demand for meat in Indonesia has increasingly become a main concern over the last two decades due to the rising income of people, along with the increased awareness of nutrition. This condition contributes to the high number of cattle slaughtered in Indonesia, being 4 million heads / year, and this of course produces high quantity of waste derived from rumen contents. A cattle with live body weight of 300 kg has a rumen content ranging from 10 to 20% of the body weight. Accordingly, it is predicted that a total of 0.28 million tonnes of rumen fill were discarded as a consequence of its limited acceptance by the farmers to be used as animal feed. Such action not only pollutes the environment but also is a waste of potential feed.   

Feed supply becomes one of the obstacles in producing poultry products because of increasing price of conventional feedstuffs and competition with human needs. Due to the fact that feed contributes about 60-70% of poultry production costs, utilization of conventional feedstuff should be partly or totally replaced by non-conventional ones which are generally of lower quality. Rumen fill is a slaughterhouse by-product that is believed to be rich in nutrients such as complete ratio of amino acids, fats, minerals, and vitamins, especially vitamin B complex, vitamin C and minerals. Several unidentified growth promoters as a result of rumen microbial synthesis were also found in rumen contents (Lee et al 2000; Morgavi et al 2000).  

Although rumen fill has beneficial compounds, its high crude fibre content (59% neutral detergent fibre in DM) limits the use of this by-product (Abouheif et al 1999). Actually, there are potentially a lot of benefits for poultry industry to utilise rumen fill if ways can be invented to tackle the problems associated with the high fiber content. It is for this reason, two studies were conducted to evaluate the nutrional profile of centrifuged rumen fill and its effect on protein digestibility, apparent metabolizable energy corrected for nitrogen, body weight gain, feed intake and carcass percentage of broiler chickens.

Material and Methods

Experiment 1. Nutritional profile of centrifuged rumen fill and its effect on protein digestibility and apparent metbolizable energy corrected for nitrogen (AMEn) of the diet containing centrifuged rumen fill.

Rumen fill collection 

Rumen fill was collected from slaughtered cattle at a local slaughterhouse. Rumen fill was covered with muslin cloth and then pressed manually to get rumen fluid. The rumen fluid was then centrifuged at 3000 rpm for 10 minutes. The supernatant fraction was decanted and the solid residue was collected as centrifuged rumen fill (CRC). The CRC was oven-dried and analysed for proximate fractions, gross energy, acid and neutral detergent fiber.   

Animal and diets 

One hundred 3-weeks old broiler chickens were purchased and randomly alocated into metabolism cages. The birds were kept for two weeks and fed experimental diets with five different treatments: RC0 = control diet;  RC1 = control diet + 1% CRC; RC2 = control diet + 2% CRC; RC3 = control diet +3% CRC; and RC4 = control diet + 4% CRC. The birds were fed twice a day; namely at 08.00 and 16.00. During the experiment, the diets and water were offered ad-libitum.

Feed and faecal collection 

Representative feed samples were collected soon after feed mixing and stored before being analysed.  Fecal discharges were collected daily for three consecutive days, from day 11 to 13. Total feces was weighed after discarding feather, feed and any foreign materials. About 25% of  feces were oven-dried at 60^oC for  48 hours as a sample.  

Protein digestibility = {(Protein in feed – protein in feces)/Protein in feed}  X 100  

AMEn diet = {(FI x GE diet) – (E x GE excreta) – (NR x K)}/ FI 

Where:

FI : feed intake; GE: Gross energy

NR: Nitrogen retention : Nitrogen intake – nitrogen excreta

K: Nitrogen retention corrected coefficient (8.73 Kcal/g for each g nitrogen)

Chemical analysis 

The feed samples were analysed to determine dry matter, crude protein and gross energy (GE) content (AOAC 2005). Prior to chemical analysis, the feed was ground (0.5 mm screen). For dry matter, samples were oven dried at 60^oC for 48 hours. Gross energy was analyzed using a bomb calorimeter.  Acid and neutral detergent fibre were analysed using the method of Van Soest et al (1991).

Statistical analysis 

The experimental design was completely randomized with 5 diets and 3 replicate cages. Data were analysed by analysis of variance using the Minitab 14 statistical program (Minitab 2003). Significant differences between means were tested using Tukey test (Steel and Torrie 1993). 

Experiment 2. The effect of centrifuged rumen fiil on growth performance and carcass components.

Animals and diets 

A total of 100 day old chick male broiler chickens were used as experimental animals. The birds were placed in brooder cages for 1 week and transfered into 20 replicate cages of 5 birds per cage. The birds were fed the same five experimental diets as in experiment 1. During this experiment, the animals were fed ad-libitum and fresh water was available at all times.

Carcass measurement 

On day 42, after the performance study was terminated, three birds from each experimental unit were randomly chosen and fasted overnight. On day 43, the selected birds were individually weighed and killed by cervical dislocation. The eviscerated carcasses and part of the carcasses  (breast meat, back, wings, thighs and drumsticks) were recorded as percentage of live body weight after removing the head, the shank and the internal organs.

Statistical analysis 

A completely randomized design was used in this experiment with five different diets and four replicate cages of five birds each cage.  Data were analysed by analysis of variance using the Minitab 14 statistical program (Minitab 2003). The differences between pairs of treatment means within any overall treatment effects, found significant by analysis of variance, were tested by Tukey Test (Steel and Torrie 1993).  

Results and Discussion

Proximate analysis of the fractions of CRC indicated that crude fibre of CRC (15.7%), ADF (44.2%) and NDF (45.0) was quite high (Table 2). The high crude fibre fraction found in CRC was due possibly to large amount of fibre fraction passed through the filter when collecting the rumen fluid. Lignin content was much lower in CRC than in rumen fill.  Protein content of CRC (20.6%)  relatively suits to the protein requirements for broilers in the grower and finisher stages (NRC 1994). This figure was higher than the protein content of rumen fill (14.2%) found by Abouheif et al (1999). The rationale of the higher protein content in CRC than in rumen fill is possibly only a matter of reduction in crude fibre fraction found in CRC (26.1 vs 15.7) as the fibre fraction was discarded prior to centrifugation process.

The protein digestibility and metabolizable energy increased with increased levels of CRC in the diet with coefficient of determination of R²=0.979 (Table 3; Figures 1 and 2). The birds fed the diets without CRC addition had 69.4% protein digestibility and 2678 Kcal/kg AMEn. This figure was far below the protein digestibility and metabolizable energy of feed containing 4% CRC. It is hard to explain these findings. It is possibly through two modes of actions. First, the CRC still contains enzymes or beneficial metabolites produced by rumen microorganisms and the process of producing CRC did not destroy the activity of the enzymes and metabolite compounds. According to Williams and Withers (1992), products that are derived from a biological process in the rumen are microbial cells or biomass, enzymes (hemicellulases, galactosidases, cellulases, amylases and xylanases), primary metabolite, secondary metabolite compounds and chemical compounds from bioprocess of microbes. It is for this reason that the addition of higher CRC in the diet increased metabolizable energy due possibly to increased fibre fraction digestibility. Second, it is possible that the nutrent fraction in CRC was easily digested due to the fact that feed materials in the rumen have undergone digestibility process by microorganisms. A further study is needed to clarify this speculation.

Figure 1. Correlation between protein digestibility and CRC levels in the diets

Figure 2. Correlation between metabolizable energy and CRC levels in the diets

 Live weight gains increased as the level of CRC in the diet was increased (Table 4; R²=0.99; Figure 3).  The reason behind this improvement of body weight gain due to CRC diets is unclear. It is possible that this is because of improved protein digestibility and higher metabolizable energy (see Table 3). Birds fed the diets containing CRC utilized feed more efficiently than unsuppplemented birds (R²=0.99; Figure 4). Since there is no published study on this aspect of the use of CRC, it might be too early to claim the postive effect of using CRC  in broiler diets.

Figure 3. Correlation between body weight gain and CRC levels in the diets

Figure 4. Correlation between FCR and CRC levels in the diets

The carcass percentage was not affected by the addition of CRC in the diet. The same trend was found in most of the components of the carcasses, except for percent breast meat which increased with level of CRC in the diet.

Conclusions

• The use of 4% centrifuged rumen fill improved protein digestibility and apparent metabolizable energy corrected for nitrogen.

  
  

• Body weight gain of birds and feed conversion ratio were improved due to supplementation of the diet with centrifuged rumen fill.

  
  

• Percent of breast muscle in the carcass increased with level of centrifuged rumen fill in the diet.

References

Abouheif M A, Kraides M S and Al-Selbood B A 1999 The utilization of rumen content-BarleyMeal in diets of Growing Lambs. Asian - Australasianian Journal of Animal Science 8: 1234-1240.

AOAC 2005  Official Methods of Analysis of AOAC International.  Horwitz, W.ed., 17^th ed. Gaitherburg, Maryland.                                                           

Lee S S, J K Ha and K J Cheng 2000  Relative contributions of bacteria, protozoa and fungi to in vitro degradation of orchard grass cell walls and their interactions. Applied  and Environmental Microbiology 6: 3807-3813. 

Minitab 2003 Minitab user's guide. Data analysis and quality tools. Release 14 for windows. Minitab Inc, Pennsylvania, USA 

Morgavi D P, K A Bauchemin, V L Nsereko, L M Rode, A D Iwaasa, W Z Yang, T A Mc Alister and Y Wang  2000  Synergy Between Ruminal  Fibrolytic Enzymes and Enzymes from Trichoderma longibrachiatum. Journal of  Dairy Science 83: 1310-1321. 

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Williams A G and S E Withers 1992 Changes In The Rumen Microbial Population and Its Activities During The Refaunation Period After The R Eintroduction of Cilliate Protozoa Into the Rumen Of Defaunated Sheep. Canadian Journal of Microbiology 39:61 -69.

Received 18 November 2013; Accepted 20 December 2013; Published 4 February 2014

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