Effects of mixtures of coconut and palm kernel oil on the rumen fermentation parameters and microbial population of cattle

O O Adelusi, C F I Onwuka, I O Anifowose¹, V O A Ojo² and K O Yusuf

Department of Animal Nutrition, Federal University of Agriculture, P. M. B 2240, Abeokuta, Nigeria
adelusioludotun@yahoo.com
¹ Department of Veterinary Medicine and Surgery, Federal University of Agriculture, Abeokuta, Nigeria
² Department of Pasture and Range Management, Federal University of Agriculture, Abeokuta, Nigeria

Abstract

The study evaluated the effects of coconut oil and palm kernel oil ratios on the rumen fermentation parameters and microbial population of cattle. The experiment tested the effects of four levels of coconut: palm kernel oil (CNO-PKO) ratios (0:0 g/day, 100:50 g/day, 50:100 g/day and 75:75 g/day) on twelve White Fulani cattle over a period of twelve weeks. All the experiments were set out in a completely randomised design. Data including rumen temperature, rumen pH, volatile fatty acids (VFA), ammonia nitrogen and rumen microbial population were collected and analysed using one-way analysis of variance.

Increased supplementation of CNO-PKO from 0:0 g/day to 75:75 g/day increased VFA from 2.52 mM to 4.31 Mm while protozoa population was reduced from 756 FEC/g to 0.00 FEC/g respectively. In conclusion, CNO-PKO at 75:75 g/day increased total volatile fatty acids and propionate proportion while protozoa population was reduced.

Keywords: fatty acids, lauric acid, methanogens, protozoa

Introduction

The rumen is principally a fermentation space in which microbial attack helps digest the diet. The partly fermented food and the micro-organisms pass through the omasum, into the abomasum and then into the small intestine. The products of microbial fermentation, mainly volatile fatty acids (VFA) and microbial protein, are available for absorption in the small intestine while the gases (carbon dioxide and methane) are eructated (Bayat and Shingfield 2012). The emission of methane from the rumen can represent a loss of up to 15% of the digestible energy, depending on the type of diet and enteric methane contributes approximately 30-40% of the total methane produced as greenhouse gas from agricultural sources (Moss et al 2000).

There has been an increasing interest in exploiting new products as feed additives to solve the problem of wastes from partial digestibility in animal nutrition and livestock production (Wang et al 2000; Greatherd 2003). Organic acids and oils have attracted attention for their potential as alternatives to feed antibiotics and growth promoters in livestock (Wallace 2004).

Dietary manipulations using these alternative feed additives have been found to also result in methane reduction by decreasing fermentation of organic matter in the rumen by shifting the site of digestion from the rumen to the intestines, diverting hydrogen away from methane production during ruminal fermentation, inhibiting methanogenesis by ruminal bacteria or by optimising the rumen fermentation and thereby decreasing methane emission per unit of organic matter digested (Benchaar et al 2001).

Blaxter and Czerkawski (1966) highlighted a high potential of medium-chain fatty acids to suppress total digestive tract methane release in ruminants. Oils extracted from plant sources usually contain a favourable amount of medium- to long-chain fatty acids. Refined soy oil fed to beef bulls at 6% inclusion reduced methane production by 39% in terms of litres per day (l/d) (Jordan et al 2006). Sunflower oil is more often studied and has resulted in reduction in methanogenesis (McGinn et al 2004; Beauchemin et al 2007). Sunflower oil has also been combined with linseed oil at a ratio of 1: 3 and fed to sheep on a pasture based diet in a dose-response trial, but at 1.2-5% oil inclusion on a dry matter basis, there was no significant reduction in methanogenesis (Cosgrove et al 2008). Linseed oil supplemented at a level of 5% of DM to lactating dairy cows resulted in a 55.8% reduction in grams of methane per day (Martin et al 2008).

Coconut and palm kernel oils have lauric to myristic acid ratios of 2.6: 1.0 and 3:1 respectively, and these are similar to the effective ratios recommended for methane abatement by the in vitro study of Soliva et al (2004). It is expected that these oils due to high amounts of lauric acid would provide significant alterations in rumen fermentation and thereby affect methanogenesis in vivo. It has also been suggested that combinations of phytoactive compounds of different oils may result in additive and/or synergetic effects (Benchaar et al 2009). As a result improving of microbial fermentation and nutrient utilization in rumen may improve energy status.

This study therefore aimed to evaluate the effectiveness of coconut and palm kernel oils at reducing methane production and manipulating rumen fermentation by affecting the proportion of volatile fatty acids and reducing protozoa population while maintaining the performance of cattle.

Materials and Methods

Location

The experiment was carried out at the Cattle Production Venture Farm, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria. The site is located in the rain forest vegetation zone of South-Western Nigeria on Latitude 7^o 13ʹ 58.19ʺ N, longitude 3^o 25ʹ 10.36ʺ E and an elevation of 145m above the sea level (Google Earth, 2013). The climate is humid with a mean annual rainfall of 1,037mm and mean temperature and relative humidity of 34.7^oand 83% respectively.

Treatments and experimental design

Four (4) treatments made of coconut-palm kernel oil (CNO-PKO) combination ratios were set out in a completely randomised design. The levels are 0:0 g/day (control), 100:50g/day (high coconut oil: low palm kernel oil (HCLP)) and 50:100g/day (low coconut oil: high palm kernel oil (LCHP)) and 75:75g/day (equal coconut and palm kernel oil (ECP)).

Experimental ingredient and animals

Weights of individual treatments were measured and mixed using a sensitive scale, while volume for weight measurements was used for on toward daily administration. The mixed samples were bathed in warm water every morning and allowed to cool before administration to the animals.

The animals for this experiment were sourced from the herd maintained under the Cattle Production Venture scheme of Federal University of Agriculture, Abeokuta. Twelve (12) White Fulani cattle with average weight of 164±2.81kg were used for this trial that lasted for 12 weeks. They were adapted for a period of 3 weeks before being randomly allotted into various treatment groups. The animals were classified into 4 groups according to the levels of coconut-palm kernel oil ratios that make up each treatment. The animals were drenched daily between 07:00 and 08:00 hours with the treatment factor before being released for grazing at 10:30 hours. Concentrate supplement was made available to the animals prior and after grazing periods.

Rumen fluid collection

One hundred millilitres of rumen fluid sample was obtained from each cattle after 12 weeks of oil administration period. Samples were collected by means of a stomach tube thrust directly into the rumen compartment via the oesophagus of the animals. Immediately after collection, the pH of the rumen samples was measured using a pH and temperature meter (HANNA instruments HI 98153). The samples were freed of coarse particles by filtration through cheese cloth and were divided into three portions for various analyses.

Determination of volatile fatty acid concentrations and ammonia nitrogen of rumen fluid

The first portion (50ml) of the sample filtrate was acidified with 1ml of a 5% (v/v) orthophosphoric acid solution and stored frozen at -20^oC in air tight bottle containers for subsequent determination of volatile fatty acid (VFA) concentrations. Total volatile fatty acids distillate concentration was determined by titration of sample with 0.1N NaOH solution and expressed as volatile fatty acid content. The procedure was a modified protocol that replaces the conventional titration with the potentiometric titration system. The concentration of NaOH solution was matched with volatile fatty acid content in samples for all the samples (Siedlecka et al 2008).  Methane gas production was calculated from the various proportions of the volatile fatty acids using the formula prepared by Ørskov et al (1968). The formula is expressed as:

Methane = 0.5 (Acetate) – 0.25 (Propionate) + 0.5 (Butyrate)

A second portion (10ml) was used for the determination of ammonia concentration as described by Lanyansunya et al (2007).

Rumen microbial analysis

The last portion (40ml) of rumen fluid samples was fixed with 10% formalin solution (1:9 v/v, rumen fluid: 10% formalin) for measuring microbial population by total direct count of bacteria, protozoa and fungal zoospores (Galyean 1989). A further identification and isolation analysis was carried out using the Anaerogen pack for anaerobes.

Statistical analysis

The data from this experiment were analysed separately using one-way analysis of variance option of the IBM SPSS Statistics software (Version 20; IBM SPSS 2011). Treatment means were compared using Duncan’s Multiple Range Test to identify differences between means; significant differences were declared at P<0.05.

Results and discussion

Effects of coconut and palm kernel oil ratios on the temperature, pH, rumen fermentation parameters of cattle

Rumen temperature was highest (p<0.05) for cattle maintained on the control and HCLP administration levels recording 31.16°C and 31.36°C respectively while the lowest (p<0.05) was obtained from cattle maintained on  LCHP and ECP administration recording 25.79°C, and 27.16°C respectively. The highest (p<0.05) rumen pH was obtained from those maintained on 0g/day oil administration recording 7.23 while the lowest (p<0.05) was obtained from cattle maintained on HCLP administration with 6.96.

Total volatile fatty acid (VFA), acetate, propionate, butyrate, isobutyrate, valerate, isovalerate and methane were highest for cattle maintained on ECP administration while the lowest values were obtained from cattle maintained on LCHP administration (Table 2)..

Rumen fermentation parameters in this study were increased by the supplementation of mixtures of coconut and palm kernel oils to cattle which can be attributed the rich amount of lauric, myristic, capric and caprillic acids. This is in contrast to the observation of Hristov et al (2004)  that acetate concentration was decreased by capric acid, with no effect on propionate concentration. Ajisaka et al (2002) reported no effect on total volatile fatty acids but increased molar proportion of propionate with the addition of capric and caprillic acids. The author also reported that these fatty acids decreased ammonia but increased the concentrations of reducing sugars. However from the result in this study, these acids were not inhibitory to bacterial proteolytic activity, with increased amounts of rumen ammonia. Pantoja et al (1994) observed that the efficiency of microbial protein synthesis in the rumen increased linearly with the degree of unsaturation in dietary fat for dairy cows.

The effect of mixture of medium-chain saturated fatty acids was more pronounced on ruminal fermentation with increase in total volatile fatty acid production with attendant reductions in the acetate: propionate ratio was observed. The effect of the reduction in this ratio on methane was however countered by the high production of butyrate in cattle fed ECP and thereby impacting the result observed in the stoichiometric volume of methane. Individual VFA proportions are known to be mainly responsible for methane;  acetate and butyrate promote its production while propionate formation is considered a competitive pathway for hydrogen use in the rumen (McAllister and Newbold 2008). Lower stoichiometric methane recorded in cattle fed LCHP are a result of the lower amounts of volatile fatty acids produced, and this can be adduced to decreasing fermentation of organic matter in the rumen which alters the site of digestion from rumen to the intestines (Benchaar et al 2001)

Effects of coconut and palm kernel oil ratios on the rumen ecology of grazing White Fulani cattle.

Rumen anaerobic bacteria in the genus Bacteroides spp. were not significantly affected by the treatments. Clostridium spp population in the control group recorded the highest count of 6.08 × 10⁶cfu/ml while the lowest number was recorded from cattle maintained on HCLP administration with 2.35 × 10⁶cfu/ml. Rumen Lactobacillus spp population of cattle was lowered by HCLP and LCHP administration with both recording 0.05 × 10⁶cfu/ml. Henderson (1973) reported inhibition of the growth of several ruminal bacteria by myristic and stearic acid at low concentrations; linoleic acid had a stimulatory effect, but at higher concentrations also decreased bacterial growth.

The rumen protozoa population of the cattle was reduced by oil administration. The highest protozoa numbers were obtained from cattle maintained in the control group recording 755 FEC/g (faecal egg count (FEC)) while the lowest (p<0.05) was obtained from cattle maintained on ECP administration recording 0.00 FEC/g.

Hristov et al (2004) reported that capric and lauric acids at all levels completely eradicated ruminal protozoa, decreased bacterial incorporation of nitrogen, and significantly shifted the concentrations of fermentation end products, compared with controls.

A study conducted by Matsumoto et al (1991) reported a strong in vivo inhibitory effect of capric and lauric acids on ruminal protozoa in goats. In that study, protozoa were completely eliminated from the rumen after 2 d of feeding caprillic and lauric, and after 3 d of feeding C₁₄. This same total suppression was observed in the mixture of oils used in this experiment with no values recorded for protozoa with ECP.

Similarly, Ajisaka et al (2002) reported complete eradication of protozoa in vitro by capric (0.17 to 0.67 mg/mL) and lauric acid (0.33 to 0.67 mg/mL) cyclodextrin complexes. Additionally, ruminal protozoal populations were shown to decrease linearly with increasing the degree of unsaturation of dietary fats (Oldick and Firkins 2000). However, the reduction in protozoa count did not affect the stoichiometric methane recorded and this can be because the oil mixture had no deleterious effects on the bacterial populations that are directly responsible in methanogenesis. As reported by Morgavi et al (2010), the complexity of the rumen microbial ecosystem means that a myriad and not just a small group of microorganisms regulate and can therefore alter methane production.

Conclusion

• Mixtures of coconut and palm kernel oils as supplement for grazing cattle resulted in increases in total volatile fatty acids, acetate, propionate and butyrate.

  
  

• Rumen ammonia concentration of animals were not affected.

  
  

• Rumen protozoa population, Clostridium spp., Lactobacillus and fungi zoospores were reduced by the oil mixture.

Acknowledgements

The authors gratefully acknowledge the support of Cattle Production Ventures, Federal University of Agriculture Abeokuta, Nigeria.

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Received 15 March 2015; Accepted 20 April 2015; Published 2 July 2015

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