Effect of multinutrient block on feed digestibility and performance of goats fed maize stover during the dry season in south of Mozambique

O L J Faftine and A M Zanetti*

Direcção de Ciências Animais
Instituto de Investigação Agrária de Moçambique
* Faculdade de Zootecnia e Engenharia de Alimentos
Universidade de São Paulo, Mozambique
faftine@yahoo.com

Abstract

This study investigated the effect of feeding maize stover alone or with multinutrient block on the growth of 24 Mozambican Landim goats aging 8 months with 11 kg (±0.61) average body weight, during the dry season.

At the end of growth trial, a 5 day digestibility trial was conducted. Multinutrient block supplementation increased (p<0.05) total intake (g day ^-1) of dry matter (520 versus 279), organic matter (369 versus 220), crude protein (67.8 versus 12.5), neutral detergent fibre (293 versus 184), acid detergent fibre (208 versus 126), hemicelullose (83.1 versus 57.5), calcium (6.04 versus 0.81) and phosphorus (5.24 versus 0.75). Goats on diet supplemented with blocks had higher (p<0.05) growth rate (9.17 versus - 7.99 g day ^-1), and higher digestibility (%) of dry matter (61.1 versus 46.6), organic matter (64.4 versus 51.9), crude protein (69.5 versus -5.60), neutral detergent fibre (55.5 versus 45.1), acid detergent fibre (53.3 versus 43.3) hemicelullose (65.1 versus 52.3) and energy (65.0 versus 57.3). The metabolizable energy intake (70 versus 30 Kcal/ kg ^0.75) and digestible crude protein (6.81 versus -0.12 g/ kg ^0.75) were higher (p<0.05) for supplemented than non supplemented goats.

Results indicate that low cost multinutrient block could reduce the live-weight losses of goats during the dry season.

Key words: crop residues, molasses, nutrition, protein, urea

Introduction

Cattle and goats produced on tropical natural pastures and crop residues such as maize stover, for example, lose more than 20% of their body weight during the dry season. This weight loss has negative economic repercussions, since it reduces the rate of conceptions, and consequently the number of births and physical condition of adult animals, causing mortality and stunted growth of young animals (Mackinon and  Rocha 1987, Cronjé 1990).

The low productivity of animals at this time is related to low efficiency of utilization of fibrous feeds due to low content of nitrogen, minerals and vitamins and high levels of lignin. Thus, the key priority for increasing animal productivity is to ensure that the digestion of stover and the proportion between protein and energy in absorbed nutrients are adequate (Preston and Leng 1987; Dixon and Egan 1988).  This effect can be achieved with the addition of non-protein nitrogen sources, and non-degradable protein in the rumen. The use of multinutrient blocks combines these two concepts, ensuring a balanced supply of nutrients to the animal. There is evidence in many countries that its use can improve the efficiency of energy utilization by ruminants and protein, thereby reducing weight losses occurring in ruminants fed crop residues or dry grass during the dry season (Sansoucy et al 1995).

The adaptation of these blocks to the conditions of Mozambique appears to be promising, considering that the quantities required per animal is minimal, its manufacture is homemade and cost of production is relatively low which may facilitate their implementation by small farmers.

The purpose of this study was to evaluate the effect of supplementation of growing goats fed with maize stover with multinutrient block on live-weight change, consumption and apparent digestibility of nutrients.

Material and methods 

Climate

The study of live-weight change, quantification of feed intake and digestibility was conducted at the Institute of Animal Production in Maputo, Mozambique, located to 33 east longitude, in the 26th latitude south and at an altitude of 40 meters, with an average annual rainfall 600 mm.

Experimental design, housing and management

Twenty four male Landim goats, 8 months old, weighing about 11 kg  ± 0.61 at the beginning of the experiment were divided by two treatments (1) maize stover and water ad libitum (basal diet) and (2) basal diet with multinutrient block ad libitum. At the beginning of the experiment all animals were dewormed with antihelmintic drug, and sprayed against external parasites. The control of external parasites continued throughout the experiment on a monthly basis.  The animals were weighed at the beginning of the experiment, and fortnightly along six months, in the morning before feeding.

 

The experiment was conducted in a completely randomized design with two treatments and 12 replications to test the hypothesis that there were differences between treatment with and without supplementation with multinutrient blocks.  The experimental data were analyzed using the statistical package (SAS 1989) to test the effect of treatment on nutritional parameters and body weight change. The difference between treatment means was obtained by subjecting all parameters to the Student t test (Snedecor and Cochran 1967).

Feeds and feeding

Maize stover was collected after harvest of maize cobs. Stover and water was provided once daily at 7 am in an individual opened paddock and after 4 pm the supplemented goats had access to block lick at an individual compartment, overnight.

The formula used in the manufacture of the blocks was based on Sansoucy et al (1995), consisting of molasses (20%), clay (20%), wheat bran (35%), cement (10%), urea (7.5%) and salt (7.5%). In this experiment, the wheat bran was replaced by copra cake. The blocks with about 2 kg were fed to the animals, and were replaced only when there remained about one quarter of the quantity supplied. 

Digestibility trial

During the last 5 days of the experiment, quantitative collection of faeces through faecal bags and the amount of stover eaten and waste by each goat were weighed and recorded daily and representative samples collected.  

The apparent digestibility of dry matter and nutrients in each treatment were calculated according to Osuji et al (1993). The gross energy (GE) of feed and faeces was calculated in the adiabatic oxygen bomb calorimeter PARR. The content of digestible energy (DE) was calculated from the difference between GE food and faeces. The digestibility was calculated according to the following equation: DE (%) = (GE feeds - GE faeces) / GE feed × 100. The metabolizable energy (ME) was determined by multiplying the DE by a factor 0.82.

Chemical analysis

Laboratory analysis of feed supplied, orts and faeces, were performed in the laboratories of the Department of Animal Science, Faculty of Animal Science and Food Engineering, University of São Paulo, Campus Pirassununga. Analyses of dry matter (DM), organic matter (OM), crude protein (CP), non-protein nitrogen (NPN), were made using the methods recommended by AOAC (1990). Total nitrogen was determined by micro kjeldahl. The contents of neutral detergent fibre (NDF) and acid detergent fibre (ADF) were analysed by the method of Van Soest et al (1991). The phosphorus (P) determination was according to the method of Fiske and Subbarow (1925). The calcium (Ca) content was determined by EDTA method (AOAC 1990).

Results and discussion  

Chemical composition of maize stover and multinutrient block

The chemical composition of the feeds used in this experiment is presented in Table 1. The levels of OM, NDF and ADF, hemicellulose and GE were higher in maize stover than in the multinutrient block. However, CP, total ash and Ca were higher in the multinutrient block. The CP content of the block was higher than in the maize stover, although 43.5% of CP was NPN.

The values of the chemical composition of stover in this study were within the ranges found in literature (Given and Moss 1995, Queiroz et al 1998, Tolera and Sundstol 2000). In turn, the multinutrient block also presented CP values similar to those found in the literature (Rajkomar 1991). However, the NDF (30.7%) and ADF (29.9%) contents were higher than values of 14.8% and 7.10% reported by Singh et al (1999), 8.2% and 4.9% observed by Toppo et al (1997) and those of 6.23% and 1.93% observed by Verma et al (1998). The ME (9.82 MJ / kg MS) in the block used in this experiment was less than the value of 11 MJ / kg MS reported by Bheekhee (1999). This reduction in energy density may be associated with a lower proportion of molasses, the high fibre content supplied by copra cake,  and also by the absence of other sources of non-structural carbohydrates such as wheat bran used in most formulations. The content of Ca (%) was also lower than the value of 5.50% found by Singh et al (1999) and Bheekhee (1999) and 6.5% found by Rajkomar (1991). The content of P was lower than the value of 0.53% found by Rajkomar (1991).

Effect of multinutrient block on voluntary intake of stover

The consumption of dry matter from maize stover, and of all nutrients were significantly stimulated (p <0.05) by supplementation of the multinutrient block (Table 2).

The increasing consumption of maize stover in the diet with multinutrient block probably occurred due to increased degradation of dry stover and rate of passage of digesta by the rumen as a result of increased activity of cellulolytic rumen microflora (Van Soest 1994). The consumption of stover is limited by the deficiency of minerals and nitrogen (Leng 1992; Given and Moss 1995). When these deficiencies are corrected by supplementation with multinutrient blocks, the consumption of stover increases.

Effect of multinutrient block on nutrient intake

The daily amount of nutrients consumed by goats in the two diets is presented in Table 3. The multinutrient block increased significantly (p <0.05) all parameters analysed. The increasing consumption of nutrients was due to increased consumption of maize stover and extra nutrients provided by the multinutrient block.

Similar results were found by Soetanto and Sarono (1988), 72.2 and 55.3 g DM / kg ^0.75 for diets based on rice straw with or without blocks, respectively,  given to goats. Singh et al (1999) also observed increase in consumption of all nutrients, when oak leaves with or without multinutrient blocks were supplied.

Effect of multinutrient block on nutrient digestibility

The values of apparent digestibility coefficients (%) of nutrients are presented in Tables 4. The diet with multinutrient block was superior in all parameters.  

These results are consistent with the results of Toppo et al (1997). However, other authors observed a reduction in digestibility of NDF and ADF when multinutrient blocks were supplied to goats (Singh et al 1999). These results were attributed to changes in the fermentation profile caused by preferential attack of microorganisms available to fermentable carbohydrates existent in molasses (Verma et al 1998).

Similarly to that observed in other experiments (Singh et al 1999; Verma et al 1998), digestibility of OM was increased.

The high apparent digestibility of CP in the supplemented animal which has supplied 78% of the total CP consumed can be related with the high content of nitrogen supplied by urea, which suffers, according to (Van Soest 1994), an almost complete hydrolysis in the rumen, turning into ammonia which is used by microorganisms for the synthesis of microbial protein.

The negative values of apparent digestibility of CP in non-supplemented animals may be associated to the low-nitrogen intake (Tolera and Sundstol 2000). To avoid such problems related to apparent digestibility experiments, Cottyn et al (1989), highlight the need to ensure that the control diet is adequate in nitrogen and sulfur for optimizing cellulolytic activity in the rumen. However, this procedure would not be relevant for the present study which aim was to compare the feeding system prevailing in Mozambique, where the animals are not supplemented.

Effect of multinutrient block on live-weight variation of growing Landim goats

Mean total and daily weight gain observed in diets with and without multinutrient block are shown in Table 5. Average daily weight gain (9.17 g) of the diet with multinutrient block was significantly higher (p <0.05) than the diet consisting solely of maize stover (-7.99 g).

Live-weight loss in the non supplemented group, indicate that the nutrients supplied by maize stover are below the requirements for goats maintenance. The daily weight gain of 9 g, observed in the supplemented group, are close to those reported by Leng (1992) when multinutrient  blocks were given to sheep fed wheat straw. The live-weight gain found in this experiment is lower than 65g considered the potential average daily gain for Landim breed (Mackinon and Rocha 1987). These results indicate that more effort should be made to improve the current block formulae to achieve better performance of goats.

Conclusion 

• The daily consumption of 180 grams of multinutrient block per kid was sufficient to maintain weight and achieve modest gains in live-weight and good physical condition during the dry season. However, live-weight gain obtained with its supplementation was far below the potential live-weight gain for Landim breed. To achieve more gains in live-weight, there is a need to study other formulas more rich in non degradable protein and soluble carbohydrate content.

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Received 29 June 2010; Accepted 1 August 2010; Published 1 September 2010

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