Dietary Albizia lebbeck leaf and millet sievate effects on digestibility, rumen environment and haematological indices of goats

Okoruwa M I, Bamigboye F O¹ and Ikhimioya I

Department of Animal Science, Ambrose Alli University, P.M.B. 14, Ekpoma, Edo State, Nigeria
odionokos@yahoo.com
¹ Department of Agricultural Sciences, Afe Babalola University, Ado – Ekiti, Nigeria

Abstract

The study was conducted to assess the effects of dietary Albizia lebbeck leaf and millet sievate supplementation on digestibility, rumen environment, haematological and growth performance of goats. Sixteen goats with initial body weight of 5.00 ± 0.85kg were housed individually and allotted to four treatment diets in a completely randomized design. The diets (DM basis) contained; 22% wheat offal without Albizia lebbeck leaf and millet sievate that served as control group (A0M0) and 4% wheat offal with either 6% Albizia lebbeck leaf plus 12% millet sievate (A6M12), 8% Albizia lebbeck leaf plus 10% millet sievate (A8M10) or 10% Albizia lebbeck leaf plus 8% millet sievate (A10M8). Goats responded to dietary supplementation of Albizia lebbeck leaf and millet sievate with increased in apparent digestibility of nutrients and rumen fermentation of volatile fatty acids and its fractions. There were decreased in feed intake and rumen ammonia nitrogen concentration with increased in haematological indices when Albizia lebbeck leaf and millet sievate were supplemented in the diets. These changes were reflected in higher weight gains and feed conversion as total mixed ration was supplemented by Albizia lebbeck leaf and millet sievate.

Keywords: blood, goats, millet-sievate, performance plant-leaf, rumen

Introduction

Goats are increasing rapidly in the tropics as they provide good quality meat and milk products to a large population of rural communities. They create alternative job opportunities and serve as source of revenue to improve livelihood resource challenged farmers. However, goat farming has reduced the level of food insecurity and received increase attention as sources of animal protein for the world growing population (Okoruwa and Ikhimioya, 2020). Ruminants are raised predominantly on natural pasture that is characterized with fibrous materials and deficient of some nutrients that hinder the efficient microbial fermentation and digestibility, most especially during the dry season (Okoruwa, 2020). Low quality and quantity of these available forages with persistent increase in cost of conventional feed ingredients has drastically reduced the performance of goats in Nigeria. Thus, nutritional problem among other global challenges has been identified as the major militating factor hampering small ruminant productivity in the tropics. This threat of feed scarcity for goats’ sustainability could be minimized by efficient use of available feed resources in once locality. This recognition necessitates research work into the use of browse plant leaves with agro-industrial by-products as feeds that could be utilized in goat nutrition (Okoruwa, 2020).

Lebbeck tree (Albizia lebbeck) that belongs to the family of leguminosae mimosoideae is such a browse plant. It has a great potential as ruminant feed supplement, due to its high protein and valuable medicinal values. Various authors (Preston and Leng, 1987; Barry and McNabb, 1999; Okoruwa, 2020 ) have noted that browse plant leaves are rich in nutrients and contain anti-microbial that enhance rumen digestion. Millet (Pennisetum glaucum) sievate (processed millet waste) is an agro by-product that has considerable amount of energy and protein needed to be exploited for livestock ration (Samuel et al., 2022). This sievate is a waste of wet milling after obtaining the flour which is prepared by milling and sieving millet soaked in water for 24 hours. It is relatively available in large amount and often discarded as waste in areas where millet is mostly consumed. The utilisation of this Albizia lebbeck leaf with millet sievate as feed could have valuable potential that will promote goat nutrition. Thus, the study was to determine the dietary of Albizia lebbeck leaf and millet sievate effects on digestibility, rumen environment and haematological indices of goats.

Materials and methods

Experimental location

The study was conducted at Ruminant Unit of Teaching and Research Farm, Faculty of Agriculture, Ambrose Alli University, Ekpoma in Nigeria, The location is between longitude 6.09⁰E and latitude 6.42 ⁰N (Ovimaps, 2019). The rainy season begins at about the end of March and lasts until early September, while the dry season begins in early October and end in early March. Temperature is uniformly high and ranges between 26⁰ C and 28⁰ C in the wet season while in dry season, it ranges between 30⁰ C and 32 ⁰ C. The annual rainfall is between 1552mm and 1556mm with relative humidity of between 76% and 80%,

Preparation of diets

Matured green Albizia lebbeck leaf was obtained from the plant branches and air dried for 3 days. Guinea grass was cut and wilted overnight before the grass and leaf were chopped separately to about 5-6cm lengths. However, millet sievate was purchased from local market within Ekpoma. It was air dried for three days to further remove any retained moisture, before thoroughly cleaned to eliminate all impurities. Guinea grass or combination of guinea grass with Albizia lebbeck leaves and millet sievate were used with other feed ingredients inform of a total mixed ration (Table,1) in the dietary treatments. The four prepared experimental diets contained; A0M0 (22% wheat offal with no Albizia lebbeck leaf and millet sievate that served as the control group), A6M12 (4% wheat offal and 6% Albizia lebbeck leaf plus 12% millet sievate), A8M10 (4% wheat offal and 8% Albizia lebbeck leaf plus 10% millet sievate) and A10M8 (4% wheat offal and10% Albizia lebbeck leaf plus 8% millet sievate). However, 60% of guinea grass and 5% of other feed ingredients were added to diets irrespective of the treatment (Table 1).

Experimental design and management of animals

Sixteen West African dwarf male goats (bucks), aged between 5 and 6 months with average body weight of 5.00 ± 0.85kg was sourced from livestock market at Ekpoma. They were kept in well ventilated individual pens that were equipped with feeders and water troughs. The animals were dewormed by using a broad spectrum anthelmintic (Super Ivermectin) according to the body weight and sprayed with acaricide (Parannex) against internal parasites. Ox-tetracycline 20% was administered to all animals to control contagious Caprine Pleural Pneumonia (CPPP) and quarantined for two weeks before the onset of the study. After the acclimatization, animals were allotted to four dietary treatments (Table 1) in a complete randomized design with two replicates per treatment in an intensive system of management. Animals were fed with experimental diets at the same time in the morning at about 8.00am. The quantity of the diet offered to each animal was calculated on the basis of 5% (DM) of their body weight. They also have access to cool fresh drinkable water without restriction. The duration of the experiment was 84 days exclusive of the 14 days acclamation period.

Weight gain and digestibility study

Feeds were offered to goats daily and the remaining amounts from the previous day offered (refusal) were measured and deducted from the feed given to determine the feed intake. Goats were weighed at the commencement of the experiment (initial weight) and then followed by weekly weighing in the morning before feeding to observe any weight change using spring balance (hanging scale), until the end of the eight-week trial. The weight gain of each goat was evaluated as the difference between the accumulated weight and the initial weight.

However, each goat was later housed in individual metabolism crates after growth study for total faecal collection. The goats had 7 days to adjust to the conduction of the metabolism crates, followed by 7 days of faecal sampling. During sampling period, feed offered and refusal with faecal were collected daily. Then, the daily faecal output was quantified (amount of fresh matter) before 10% of the homogenised daily faecal output was sub-sampled and kept in plastic bags in the freezer (-20%) for analysis. Thereafter, nutrient digestibility was determined by standard procedures outlined for direct estimation of animal digestibility (Japan Livestock Technology Association, 2000).

Rumen environment

Rumen study was preceded by digestion trial of the goats. Rumen liquid was collected through a stomach tube that was inserted through the oesophagus after three hours post feeding. The first portion (about 30ml) of the sample collected was discarded to reduce saliva contamination. The rumen liquid pH was determined immediately using a digital pH meter before weighed and made free of coarse particles by straining through layers of cheese cloth and pooled for analysis. Rumen ammonia nitrogen (NH ₃-N) concentration was determined by the method of Kjeldahl, while total volatile fatty acid (VFA) concentration and its individual fractions .determination were carried out through gas chromatography assay as described by Pirondini (2012).

Blood sampling and analysis

At the end of the experiment, blood sample (5ml) from each goat was taken from the jugular vein puncture using 5ml hypothermic syringe with needle before morning feeding. The blood was introduced into the labelled sterile test tube, containing ethylene diamine tetra-acetic acid (EDTA) as anticoagulant for determination of haematological indices, according to the standard methods reported by Coles (1986). The blood was immediately inserted in ice containers before red blood cells (RBC) count was carried out in a haemocytometer chamber with Natt and Herdrics diluents to obtain a 1:200 blood dilution. The number of leucocytes was estimated as total white blood cells ( WBC) x 200, packed cell volume (PCV) was determine as micro haematocrit with 75x16mm capillary tubes filled with blood and centrifuged at 3000 rpm for 5 minutes. Haemoglobin (Hb) concentration was calculated while differential count of leucocytes was obtained from blood stained with wrights dye and the neutrophil, lymphocyte, monocyte and eosinophil cells were counted with a laboratory counter.

Chemical Analysis

The proximate analysis of feeds, experimental diets and feaces were conducted according to standard methods of AOAC (2005). The residual dry matter of the samples was determined by oven-drying at 105 °C for 18 h. Nitrogen was determined by the micro Kjeldahl method with Tecator Product apparatus (KjeltecTM2100). The Soxhlet extraction procedure was used for the analysis of crude fat (ether extract) using electromantle ME. The ash was measured by combustion of the dried material in a muffle furnace at 600 °C for 8 h. Crude fibre, sequential neutral detergent fibre (NDF) and acid detergent fibre (ADF) were determined using Tecator Line (FT 122 FibertecTM) according to the method described by Van Soest and Wine (1967).The concentration of total tannins present in feeds and diets were determined by colorimetrically as described in AOAC (2005). The total alkaloid, flavonoid, phenols and saponin were quantified using colorimetry (AOAC 2005)

Statistical analysis and model

Data obtained from weight gain, digestibility, rumen function and haematological indices were subjected to statistical analysis using the General Linear Model (GLM) procedure of SAS 9.0 software (SAS 2002). Duncan’s multiple range tests was used to determine the significance differences between the means.

The statistical model used for the analysis was Y_ij = µ + t_i + Ɛ _ij,

Where:

Y_ij = response variable,

µ = overall mean,

t_i = effect of i^th treatment (i = A0M0, A6M12, A8M10 and A10M8).

Ɛ_ij = random error.

Results

Diets (Table,1) were formulated with graded levels of Albizia lebbeck leaf and millet sievate inclusion in form of a total mixed ration. Diet A0M0 that served as the control group had no Albizia lebbeck leaf and millet sievate, unlike test diets A6M12, A8M10 and A10M8.

Chemical composition and phyto-chemical components trend of guinea grass (GG), Albizia lebbeck leaf (AL), millet sievate (MS) and experimental diets were examined (Table 2). The AL had highest value of crude protein but MS marked lowest value in crude fiber and its fractions. However, remarkable differences were observed in phyto-chemical components of feed ingredients and treatment diets according to the type of plant materials used in the study.

The influenced of Albizia lebbeck leaf meal supplementation in the diets showed positive responses in weight gain and feed conversion as seen in figure 1,2 and 3. Furthermore, this tremendous changes were also reflected in the improvement of apparent digestible of dry matter and enhancement of digested nutrients (Table,3).

The relevant of goats consuming increased proportion of Albizia lebbeck leaf meal in the total mixed ration did not affect rumen pH but perhaps supported higher values of rumen fermentation of volatile fatty acids. (Table,4). However, the most important benefits from this leaf meal supplementation were seen in decreased values of ammonia nitrogen concentration and increased in the proportion of rumen propionic acid fermentation. Haematological indices were not adversely affected by the diets as well but tended to show increase in values except monocytes and eosinophils that were not unaffected.

Figure 1. Relationship between consumption of Albizia lebbeck leaf meal and daily weight gain in goats fed diets supplemented with Albizia lebbeck leaf and millet sievate	Figure 2. Relationship between Albizia lebbeck leaf intake and feed conversion in goats fed Albizia lebbeck leaf and millet sievate supplements
Figure 3. Relationship between feed intake and feed conversion in goats fed diets with Albizia lebbeck leaf and millet sievate supplements

Discussion

Dietary supplementation of Albizia lebbeck leaf meal supported optimal nutrient utilization and productivity of goats. It was stressed by Preston et al. (2021) that trees and shrubs should be the first choice as source of by-pass protein as this will combine with the environmental benefits inherent in perennial species. The key factor to this potential benefit of this leaf meal as a source of by-pass protein was escape of nutrients fermentation in the rumen that goes to the intestine for more efficient feeds utilization by enzymic digestion. This also determines the degree to which the energy in the feed is used for productivity purpose and minimized methane emission (Preston et al., 2021). The positive influence of phyto-chemical components in the leaf could probably modify digestion of these diets in ways that relates to enhancement of digestibility and facilitated positive changes in rumen fermentation characteristics. This was reflected in the reduced production of methane through direct inhibition of methanogenic bacteria, which facilitates positive changes in the rumen fermentation as the hydrogen not taken up by methanogenic bacteria results in increased production of propionic acid, which is the major precursor of glucose for more improved growth feed conversion (Preston and Leng, 1987; Okoruwa and Ikhimioya, 2020) as seen in Tables 3 and 4. At the same time, these employed test diets also attributed to better health status observed in the goats. This observation is in agreement with the work of Okoruwa,(2020) who reported that supplementing tree leaves with crop residues improve immune system of goats.

There was no much benefit in feed intake of goats on diets with leaf meal, apparently tannins present in the test diets could responsible for this slight decreased in consumption. This finding tally with the report of Ibrahim et al.(2020) who noted that tannin has negative impact on feed consumption of yankasa sheep due to its residue effect on diets. A more likely explanation was also seen in the effect of tannin in diets reacting with the dietary protein to protect them from rumen microbial attack. This encounter facilitated the increased of some protein escape (by-pass protein) from the rumen for more efficient enzymic digestion in the intestine (Barry and McNabb, 1999; Okoruwa and Ikhimioya, 2020) as noticed in the reduction of ammonia nitrogen concentration in the leaf meal diets (Table 4) that could associated with feed utilization efficiency and weight gain.

Conclusions

• Inclusion of Albizia lebbeck leaf and millet sievate in the diets tended to improve weight gain, feed conversion and rumen volatile fatty acids with enhanced digestibility of goats.
  
  
• There were consist reduction of feed intake and rumen ammonia nitrogen concentration in the present study when supplementing Albizia lebbeck leaf in the diets.
  
  
• It can therefore be concluded that up to 6-10% of Albizia lebbeck leaf and 8-12% of millet sievate levels of inclusion in the diets improved growth performance without compromising the health status of goats.

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