Effect of coconut oil and cassava hay supplementation on rumen ecology, digestibility and feed intake in swamp buffaloes
 

A Phengvilaysouk and M Wanapat^*

Livestock Research Center, National Agriculture and Forestry Research Institute,
Ministry of Agriculture and Forestry, P O Box 811, Vientiane, Lao PDR.
ammalyp@yahoo.com
*^bTropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science,
Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand.

Abstract

This experiment focused on the effect of cassava hay (CH) and coconut oil (CO) supplementation on feed intake, digestibility and rumen ecology in swamp buffaloes. The experiment was arranged in a 4*4 Latin square design with 4 treatments and 4 replications. The treatments were: C: control, rice straw ad libitum (no supplementation), CH: rice straw ad libitum plus supplementation of cassava hay at 1 kg/hd/d, CO: rice straw ad libitum plus supplementation of coconut oil at 2 ml/kg of BW. CH+CO: rice straw ad libitum plus cassava hay at 1 kg/hd/d plus coconut oil at 2 ml/kg of BW. Four male of swamp buffaloes of 252±6.13 kg live weight were used.

The results show that supplementation of CH or CH+CO significantly increased (p<0.05) NH₃-N and blood urea nitrogen (BUN) concentration. The pH, and VFA concentration was not significantly different among treatments, but VFAs tended to increase when supplemented with CH or CH+CO. Supplementation of CO significantly reduced (p<0.05) protozoa population in the rumen. Total DM intake was highest (p<0.05) with supplementation with CH (8.4 kg/d) followed by CH+CO (8.2 kg/d) and supplementation of CO or without supplementation (6.8 and 6.2 kg/day, respectively). The digestion coefficients for DM, OM, CP, NDF and ADF were highest (p<0.05) with supplementation with CH (58.4, 59.8, 61.0, 53.4 and 60.7%, respectively) as compared with supplementation with coconut oil and with no supplementation (p<0.05). The results obtained from this study lead to the conclusion that supplementation affected rumen ecology, diet digestibility and feed intake in swamp buffaloes. When supplemented with CH or CH+CO rumen ecology and digestibility were improved. Supplementation with only CO significantly decreased roughage intake due to reducednumbers of protozoa.

Keywords: Swamp buffalo; cassava hay; coconut oil; rumen ecology; digestibility and feed intake.

Introduction

In recent years, the human population has increased rapidly, and the demand for food, in particular livestock products is expected to increase in all developed and developing countries. Livestock plays a major role in the livelihoods of small-farmers in Southeast Asia and contributes to the regional and national economic development.

The Lao PDR is a predominantly rural society with 85% of the population depending on agriculture for their livelihoods, and with most of the rural households producing food mainly for their own consumption. Agriculture, including livestock, accounts for 52% of GDP and over 95% of all livestock is owned by smallholders (Stur et al., 2002). Livestock provide many benefits, including draft power to cultivate the land, transport of agricultural products, and manure for vegetables, fruit and crop production. Animals act as a safety net for the family when cash is needed, especially for sending children to high school. In developing countries, smallholders commonly use crop wastes after harvest to feed to animals (Chantalakkana, 2001).

Most swamp buffaloes are fed on low-quality roughages, agricultural crop-residues, and industrial by-products, which basically contain high levels of cellulose, hemi-cellulose and lignin, as well as low levels of fermentable carbohydrates and poor-quality protein. However, crop residues are an available feed resource in local areas from crop cultivation and are a very important source of roughages for ruminants. Farmers usually give these feed resources, particularly rice straw, to buffaloes as their main diet during the dry season in many Asian countries. These diets result in low performance, productivity and poor health due to their low quality, because rice straw is low in available energy, protein and vitamin, has an imbalance of essential minerals, and contains a large pool of structural carbohydrates (Wanapat, 1999). However, The rumen has been long recognized as an essential fermentation vat that is capable of producing end-products, particularly the volatile fatty acids (VFA) and microbial proteins as major energy and protein sources for the ruminant host.

It has been suggested that supplementation of good quality protein can improve roughage intake and digestibility by improving the rumen ecology. Cassava is one of the most important crops as a source of protein for animals, and cassava leaf has a high crude protein concentration of from 16.7 to 39.8%, according to Allen (1984). Furthermore, cassava hay has been reported to manipulate the rumen in terms of improving rumen ecology and enhancing by-pass protein (tannin-protein complex) and hence could improve DM digestibility of low quality feed (Wanapat, 2000). In addition, it is possible to improve feed intake, digestibility and the feeding value of rice straw with oil supplementation, particularly coconut oil, which is a fat, consisting mainly of highly saturated (over 90%), and is rich in lauric acid. Saturated fatty acids are more digestible in ruminants than in non-ruminants (Palmquist and Jenkins, 1980). The purpose of this experiment was to determine the effect of cassava hay and coconut oil supplementation on feed intake and digestibility, and on rumen ecology and fermentation end-products. Supplementation of coconut oil could increase the energy concentration of the diet, and reduce the protozoa population in rumen, and the combined use of cassava hay and coconut oil could thus be beneficial for small farmers in the tropical areas.
 

Materials and Methods

Location

The experiment was conducted at the Livestock Research Center (Nam Xuang), National Agriculture and Forestry Research Institute, Ministry of Agriculture and Forestry, Vientiane Lao PDR, situated 44 km from Vientiane City. The climate in this area is divided into two seasons: dry and wet. The wet season is from May to October. Annual rainfall is on average 1400-1800 mm, and the peak rainfall occurs in the period July to August. The dry season is from November to April. Only about 1 to 2% of the annual rainfall occurs during the dry season. The average minimum and maximum temperatures are about 15^oC and 32^oC, respectively. This experiment was started in June, 2006 and finished in December, 2006.

Experimental animals

Four male buffaloes, approximately 2-2.5 years of age with live weights of 252±6.13 kg were used. All animals were confined in separate pens. Fresh water was available all times during the whole experiment. Cleaning of the pen was done daily. A vaccination program, de-worming and a vitamin A, D₃, E injection were given before the commencement of the experiment. Each animal was weighed at the beginning and the end of each period.

Experimental design, diet treatment and management

The experiment was arranged in a 4*4 Latin square design with 4 treatments and 4 replications. Four male swamp buffaloes were randomly assigned to treatments. The diets comprised of basal roughage, rice straw (RS), which was fed ad libitum, and with a rumen supplement of 200 g/hd/d. Rice straw was collected from local farms around the Livestock Research Center and transported to a store. Feed offer and feed refusals were weighed every day to calculate feed intake during the first 14 d. Cassava hay (CH) was harvested 3 months after planting by hand, and the green part cut at a height of 50-70 cm above the ground. The foliage was chopped into small pieces (2-3 cm) by chopping machine (hand-operated). After that, it was sun-dried for 2-3 days to reduce moisture (DM>85%) and hydro-cyanic acid (HCN) content. Cassava hay was stored and fed to the buffaloes according to the following treatments in two equal parts in the morning (07:00h) and in the afternoon (16:30h). Coconut oil was bought from the market. The treatments were supplementation of cassava hay or coconut oil according to respective experiments as follows:

• C: control, fed rice straw ad libitum (no supplementation)

• CH: fed rice straw ad libitum plus cassava hay supplementation at 1 kg/hd/d

• CO: fed rice straw ad libitum plus coconut oil supplementation at 2 ml/kg of BW

• CH+CO: fed rice straw ad libitum plus cassava hay at 1 kg/hd/d plus coconut oil at 2 ml/kg of BW

All animals were offered fresh water ad libitum and a rumen supplement at 200 g/hd/d of concentrate (50 g urea, 10 g suphur, 50 g salt, 50 g bone meal and 40 g molasses). Buffaloes were adapted to the diets for about 30 days prior to the first period and for intake measurement and sample collection periods during 14 and 5 d, respectively for each period.

Measurements

Body weight, feed intake and digestibility

Buffaloes were weighed at the beginning and at the end of each period for 2 consecutive days (28 days per period). Feed offer and refusals were measured daily to determine feed intake. Feed samples were randomly collected daily, and all samples were combined together and randomly sampled for dry matter (DM), ash and crude protein (CP) analysis according to AOAC (1990). The contents of neutral-detergent fiber (NDF), acid-detergent fiber (ADF) and acid-detergent lignin (ADL) were determined according to the procedure of Goering and Van Soest (1970).

The fecal samples were collected from rectum before feeding in the mornings during the last 5 days of each period. The samples were kept in the refrigerator until analyses for DM, OM, CP, NDF and ADF, with acid insoluble ash (AIA) used as an internal indicator to calculate digestibility of feed according to Galyean (1989).

Blood sampling

Blood samples of about 10 ml were taken from jugular vein into a tube by needle at 0 and 4 hr post-feeding on the last day of each period. The samples were refrigerated for 1 hr and then centrifuged at 3500 x g for 20 min. The plasma was removed and was analyzed for blood-urea nitrogen (BUN) composition according to the method of Roseler et al. (1993).

Rumen fluid

Rumen fluid samples (80 ml) were taken at 0 and 4 hr post-feeding on the last day of each period by using a stomach tube connected with a vacuum pump. Rumen fluid pH was determined immediately after sampling by pH meter and rumen fluid was fixed by adding 10% H₂SO₄ solution (1 ml H₂SO₄ to 9 ml of rumen fluid) for later analysis of NH₃-N concentration (AOAC, 1990) and VFA concentration by HPLC (Samuel, 1997). Methane (CH₄) production was estimated from the concentrations of C2, C3 and C4 according to the equation of Moss et al. (2000). The subsequent rumen fluid was immediately fixed with 10% formalin solution (1:9 v/v, rumen fluid: 10% formalin) for measuring the protozoa population (Galyean, 1989).

Statistical analysis

All data were analyzed of Variance (ANOVA) according to Latin square design using the General Linear Model (GLM) of Minitab Software Version Release 14 (2003), treatment means which showed significant differences with probability level of p<0.05 were compared using Tukey's pairwise comparison procedures. Statistical model was as follows: Y_ijk = µ +T_i + C_j + R_k +e_ijk Where = Y_ijk = The criteria under study, in treatment were (i); column (j); row (k). µ = Overall sample mean. T_i = Effect of treatment (i). C_j = Effect of treatment (i) at column (j). R_k = Effect of treatment (i) at row (k). e_ijk = Error
 

Results

Chemical composition of feedstuffs

The chemical composition of the experimental feeds is shown in Table 1. The rice straw contained 92.4% DM. The content of crude protein in rice straw, cassava hay (CH) and rumen supplement was 3.0, 21.3 and 54.6% of DM, respectively, and the level NDF, ADF and ADL in rice straw and CH was 78.2, 51.7, 12.9 and 52.4, 34.0, 10.8% of DM, respectively. Coconut oil (CO) comprises 6% oleic (C18:1); 2% linoleic (C18:2); 6% capric (C10:0); 47% lauric (C12:0); 18% myristic (C14:0); 9% palmistic (C16:0); 3% stearic (C18:0) acid (Scientific Psychic, 2005).

Rumen ecology and BUN

Rumen ecology parameters are presented in Table 2. Rumen pH, total VFA and their proportions were not affected by supplementation of CH and CO. Supplementation of CH and CH+CO resulted in significantly higher NH₃-N and BUN concentration when compared with the control and CO supplemented groups. Supplementation of CO was significantly reduced (P<0.05) protozoa population (1.2 x10⁵ cells/ml) vs (4.8 x10⁵ cells/ml) when without supplemented oil.