Citation of this paper

The effect of feeding leguminous tree foliages on performance of goats fed basal diets of grass and crop residues

M I Okoruwa

Department of Animal Science, Ambrose Alli University, P.M.B. 14, Ekpoma, Edo State, Nigeria
odionokos@yahoo.com

Abstract

Sixteen goats with initial body weight of 8.00 ± 0.96kg were housed individually and assigned to four treatment in a completely randomized block design. The diets (DM basis) were; 70% guinea grass and 30% urea-treated grass-cashew fruit silage (GSUS) and 40% guinea grass plus 30% untreated silage with 30% of either: Acacia angustissima (GSAA), Parkia biglobosa (GSPB) or Leucacena trichandra (GSLT).

The goats responded with increased feed intake and growth rate and better feed conversion when they also had access to the leguminous tree foliages suspended from the roof of the pen. It was hypothesized that the improvement in growth performance stimulated by the legume tree foliages was because of the increase in rate of eating when the legume tree branches were fed in a way that simulated “browsing”.

Keywords: Acacia angustissima, Parkia biglobosa, Leucacena trichandra

Introduction

The inadequacy and poor quality of forages is one of the major constraints hindering the productivity of ruminant livestock in tropical countries like Nigeria. Similarly, the availability and prices of high-quality feed ingredients in the global livestock industry cannot meet the need of ruminant producers especially for small farm stakeholders. Hence, the gap created between quality feed supply and demand continues increasing in rural communities (Rafiee-Yarandiet al 2019). Development and exploitation of unconventional feed resources in the tropics is a good strategy to provide feeds for ruminants (Rahman et al 2015).

The need to respond to the climate emergency by planting trees (IPCC 2014) is an opportunity to promote research to identify which trees could serve as feed for animals as well as sequestering carbon dioxide. The research described in this paper aimed to evaluate locally available leguminous trees; Acacia angustissima, Parkia biglobosa and Leucacena trichandra as feed supplements for goats fed grass and ensiled crop residues.

Materials and methods

Study Site

The experiment was conducted at the Livestock Unit of the Teaching and Research Farm of Ambrose Alli University, Ekpoma, Edo State, Nigeria.

Preparation of experimental diets

Branches from Acacia angustissima (AA) Parkia biglobosa (PB) and Leucaena trichandra (LT) were collected and air dried for 2 to 3 days. Guinea grass was wilted overnight and chopped to 6-8cm lengths. Ripe cashew apple fruits were collected, nuts were removed and the pulp mechanically pressed to reduce excess liquid before being chopped into small pieces. Maize cobs were crushed to about 2 to 3cm. Equal proportions of maize cobs and fruit pulp were mixed before being divided into two parts. Urea (2kg) was dissolved in 50 litres of water and sprinkled on one part of the mixed crop residues. Thereafter, they were separately packed in 50kg double-layer plastic bags and vacuumed to remove excess air before sealing. The feeds were ensiled for 30days. Guinea grass or a combination of guinea grass with each of the legume tree foliages was offered by hanging after being tied to bars suspended over the individual pens. Silage was placed in the feed trough. Grass and/or silage were used in all the treatment diets as the main feed. The grass and urea-treated silage were used as sole diet for the control group while grass and untreated silage with one each of the three legume tree foliages were used for the other dietary treatments

The experimental diets were thus;

GSUS: 70% guinea grass and 30% urea treated silage

GSAA: 40% guinea grass and 30% untreated silage with 30% Acacia angustissima,

GSPB: 40% guinea grass and 30% untreated silage with 30% Parkia biglobosa

GSLT: 40% guinea grass and 30% untreated silage with 30% Leucacena trichandra

Animals and management

Sixteen growing goats, aged 9 – 10 months with initial mean live weight of 8.00± 0.96kg were kept in individual pens with roofing and concrete floor. After the adaptation, when the feed intake was stable, animals were weighed and recording began. The experiment was arranged as a completely randomized block design with four treatments and four replicates per treatment. The goats were blocked by the initial body weight. Feeds were offered twice per day at 8:00am and 4:00pm. The percentage ratio of the tree foliage to the grass and silage was used to determine the proportion of each tree branch in the daily feed allowance offered to each goat.The amount of feed offered was adjusted after every week according to live weight change. The goats had free access to fresh water. The experiment lasted for 90 days exclusive of a 14 day adaptation period.

Measurements

Records of daily feed offered and refusals were collected from individual animals in the morning of the next day and used to compute the feed intake. Feeding behaviour of the animals was monitored by two people during periods of 24 hours once weekly throughout the trial. The time spent in eating and ruminating was recorded. The eating rate and ruminating rate were calculated in accordance with the report of Theng Kouch et al (2003);

Eating rate (g/minute) = total DM intake (g)/eating time (minutes).

Ruminating rate (g/minute) = total DM intake (g)/ruminating time (minutes).

Goats were weighed at the commencement of the study and subsequently on weekly basis. At the end of the growth trial, the goats were transferred to individual metabolism cages. Daily feed offered, leftovers and fecal and urinary outputs were collected for 7 days and stored separately in a refrigerator following 7 days of adjustment period. Fecal samples for each goat were bulked, mixed and about 10% of sub-sample kept in plastic bags in the freezer (-20 °C). Urine sub-samples were collected in plastic bottles with 4 drops of diluted sulphuric acid (10% H₂SO₄) to prevent loss of nitrogen. Digestibility coefficents and nitrogen balance were calculated based on dry matter intake and outputs of feces and urine.

Chemical analysis

Feeds and faecal samples were dried for 48h at 60⁰C in a forced – air oven to determine the dry matter (DM) content before being milled to pass through a 1mm screen for proximate composition and phenolic compounds, following the procedures of AOAC (1990).

Statistical analysis

Data generated from the experiment were subjected to descriptive statistics and analysis of variance using the general linear model (GLM) application in the ANOVA programme of the MINITAB (2000) software (version 16.0). Sources of variation were treatment, block and error. The statistical model used for the analysis was: Yijk = G + Ai + Bj+ Eijk

Where; Yijk = dependent variable, G = overall means, Ai = effect of the treatment i, Bj = effect of the block (initial animal weight), Eijk = effect of random error

Results

Proximate composition and trends in phenolic compounds in the forage tree legumes and experimental diets are reviewed inTable 1 and Figure 1

Table 1. Proximate composition and anti-nutritional components of leguminous forage trees and experimental diets (%DM except for dry matter which is on air dry basis)
	Leguminous forage trees			Treatment diets
	AA	PB	LT	GSUS	GSAA	GSPB	GSLT

Dry matter	79.9	81.7	84.6	69.8	75.9	77.8	79.3
Crude protein	17.8	18.3	20.2	10.5	11.2	11.4	11.9
Ether extract	3.83	2.91	4.06	1.78	2.21	2.01	2.46
Crude fibre	23.5	26.8	20.1	33.0	31.9	32.4	30.1
Ash	8.24	6.47	5.39	6.98	5.59	5.19	4.92
Nitrogen free extract	46.6	45.5	49.5	48.1	49.3	48.9	50.1
Phenolic compounds
Tannin	0.68	0.82	0.76	0.87	1.32	1.71	1.56
Saponin	0.83	0.57	0.78	0.59	0.81	0.73	0.84
Oxalate	0.23	0.19	0.58	0.66	0.66	0.53	0.75
Phytate	0.19	0.30	0.51	0.54	0.59	0.67	0.73
AA = Accia angustissima, PB = Parkia biglobosa, LT = Leucacena trichnadra

Figure 1. Phenolic compounds in the leguminous tree leaves

The increased rate of feed intake when the basal grass-silage diets were supplemented with legume tree foliage (Table 2; Figure 2), was reflected in greater daily feed intake and improved live weight gain and feed conversion (Table 2; Figures 3, 4 and 5).

Table 2. Mean values for feed intake, feeding behaviour,live weight change and feed conversion of goats fed grass and silage diets supplemented with leguminous tree foliage
	Treatments				SEM	p
	GSUS	GSAA	GSPB	GSLT	SEM	p

Feed intake, g/d	289^c	320^a	315^b	322^a	0.93	0.020
Eating time, min/24h	304^a	271^c	288^b	275^c	1.32	0.031
Ruminating time, min/24h	180^b	232^a	222^a	230^a	1.41	0.024
Eating rate, g DM/min	0.95	1.18	1.09	1.17	0.02	0.010
Ruminating rate, g DM/min	1.60	1.38	1.42	1.40	0.01	0.002
Live weight, kg
Initial	9.32	8.80	9.11	8.62	0.47	0.013
Final	11.6^b	11.9^b	12.1^a	11.1^b	0.16	0.008
Live weight gain, g/d	30.0^c	40.8^a	39.3^b	41.8^a	0.48	0.024
Feed conversion#	9.63^a	7.84^c	8.01^b	7.70^c	0.08	0.006
^a,b,c Means in the same row without common superscript differ at p < 0.05; # Feed intake/live weight gan


Figure 2. Eating rate of goats fed leguminous tree foliages as supplements to grass/silage	Figure 3. Relationship between eating rate and feed intake in goats fed grass/silage diets supplemented or not with leguminous tree foliage

Figure 4. Relationship between eating rate and live weight gain in goats fed grass/silage diets supplemented or not with leguminous tree foliage	Figure 5. Relationship between eating rate and feed conversion in goats fed grass/silage diets supplemented or not with leguminous tree foliage

The positive response in feed intake, growth rate and feed conversion, due to increased rate of eating, was reflected in improvements in apparent digestibility of DM, crude protein and crude fibre and enhanced N-retention (Table 3; Figures 6 and 7).

Table 3. Mean values for apparent digestibility and nitrogen retention of goats fed diets supplemented with legume tree fooliage
	Treatments				SEM	p
	GSUS	GSAA	GSPB	GSLT	SEM	p

Digestibility, %
Dry matter	67.8^c	72.4^b	71.2^b	74.7^a	0.29	0.034
Crude protein	59.9^c	71.5^a	69.8^b	73.9^a	1.34	0.026
Crude fibre	66.7^b	68.3^b	67.9^b	70.6^a	0.86	0.009
Nitrogen balance, g/d
N intake	9.26^b	10.4^a	9.99^a	10.7^a	0.42	0.031
Faecal-N	2.89	2.52	2.76	2.43	0.12	0.005
Urinary-N	2.32^a	1.37^b	1.75^b	1.48^a	0.34	0.012
N-retention	4.05^c	6.51^a	5.48^b	6.79^a	0.46	0.074
^a,b,c Means in the same row without common superscript differ at p < 0.05


Figure 6. Relationship between eating rate and DM digestibility in goats fed grass/silage diets supplemented or not with leguminous tree foliage	Figure 7. Relationship between eating rate and N retention in goats fed grass/silage diets supplemented or not with leguminous tree foliage

Discussion

Supplementing the basal diets of grass and grass-cashew fruit silage with branches of leguminous trees, in a way that simulated browsing, had a positive impact on all production traits: feed intake, live weight gain and feed conversion. It was also apparent that this feeding method increased feeding efficiency by reducing the time spent per unit DM consumed. In turn this appeared to facilitate the process of digestion. These results are broadly in line with the report of Theng Kouch et al (2003) which showed that suspending tree and shrub foliage above the feed trough, to facilitate browsing, supported higher feed intakes compared with placing the branches in the feed trough; stripping the leaves from the branches and giving them as the sole diet supported the lowest feed intake.

Figure 8. Effect of method of presenting tree foliages to goats on
their rate of eating (from Theng Kouch et al 2003)

Conclusions

Goats fed basal diets of grass and grass-cashew fruit silage responded with increased feed intake and growth rate and better feed conversion when they also had access to leguminous tree foliages suspended from the roof of the pen.
It was hypothesized that the improvement in growth performance was linearly related to the increase in rate of eating when the legume tree branches were fed in a way that simulated “browsing”.

References

AOAC 1990 Official Methods of Analysis. Association of official analytical chemist, 15^thEdition (Khelrick, editor) Arlington pp 1230.

IPCC 2014 Climate Change 2014. Synthesis Report Contribution of Working Groups I, II and III to the fifth Assessment Report of the Intergovemmental Panel on Climate Change (Core Writing Team, R. K Pachauri and L.A Meyer (eds) ). IPCC, Geneva, Switzerland, 151 pp.

MINITAB 2000 Minitab Statistical software, Release 10.2 Minitab Inc. State College PA, USA

Rafiee-Yarandi H, Alikhani M, Ghorbani G R, Heydari M and Rezamand P 2019 Dietary protein level and corn processing method: intake, digestibility, and feeding behaviour of lactating dairy cows. Livestock Science, 221: 19 – 27 journal homepage; www.elsevier.com/locatate//ivsci.

Rahman Z, Akbar A, Hossain A and Ali Y 2015 Effect if tree forage supplementation on growth performance of goats. Asia Journal of Medical and Biological Research,1(2): 209 – 215.

Theng Kouch, Preston T R and Ly J 2003 Studies on utilization of trees and shrubs as the sole feedstuff by growing goats; foliage preferences and nutrient utilization. Livestock Research for Rural Development. Volume 15, Article #50. http://www.lrrd.org/lrrd15/7/kouc157.htm

Received 26 May 2020; Accepted 12 June 2020; Published 1 July 2020

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