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58
Res. Rev. J Ecol. Environ. Sci.| Volume 5 | Issue 4 | October - December, 2017
e-ISSN:2347-7830
p-ISSN:2347-7822
Research & Reviews: Journal of Ecology and
Environmental Sciences
Nutritive Value of
Hyparrhenia anamesa
Dominated Natural Pasture
and its Impacts on Seminal Traits of Horro Rams
Abera Seyoum* and Debisa Lemessa
Ethiopian Biodiversity Institute, Forest and Rangeland Plants Biodiversity Directorate, Addis Ababa,
Ethiopia
Research Article
INTRODUCTION
In tropical region, feed resources are mainly natural pastures and agricultural by-products. But these feed resources are
mostly low in protein content and digestible energy [1]. Similarly in Ethiopia livestock feeding is often based on natural pasture
and crop residues which are generally poor in nutritive value. Moreover, the Ethiopian natural pastures are decreasing, because
of conversion of pasture lands to crop production triggered by increasing human population pressure. As a result the existing
pasture cannot meet the nutritional requirement of livestock resulting in reduced growth rate, low production, poor fertility and
high mortality [2]. In the western parts of Ethiopian, Horro breed of sheep is an integral part of farming system and predominantly
a basic asset for the livelihood of the society, where sheep production is mostly inuenced by the seasonal scarcity and low
quality of feed resources as feed availability and quality primarily depends upon the climatic and seasonal factors, and this is a
challenge for the reproductive performance of livestock [3]. Among environmental factors that affect the reproductive phenomena
of livestock, nutritional factors are the most crucial in terms of their direct effects and the potential to moderate the effects of
other factors [4]. Under nutrition resulted in reduced sperm output, decreased sperm motility, and an increased in the proportion
of morphologically abnormal spermatozoa in the ejaculate, alters the endocrine and hormonal activities in livestock leading to
decline in reproductive efciency [5]. Thus, for better animal performance and sustainable use of the grazing resources, evaluation
ABSTRACT
Evaluation of pasture is often suggested to improve the productive and
reproductive performance of livestock and proper utilization of the grazing
land. However, this has got little attention in western Ethiopia. Here, a study
was conducted to evaluate the nutritive value of Hyparrhenia anamesa grass
dominated natural pasture and its impacts on seminal traits of Horro rams, at
Bako Agricultural, Technical and Vocational Education and Training College,
west Ethiopia. One hectare of grazing land was demarcated and eighteen
yearling Horro rams were allowed to graze for a grazing period of 120 days. The
biomass yield of the grazing pasture was estimated using multistage systems
where pastures were harvested from ve quadrates (1 × 1 m size) from within
the demarcated grazing land. Chemical composition of the pasture was
analysed using standard laboratory procedures. Data on seminal attributes
were taken every two weeks during the grazing period. The result showed
that natural pasture was poor both in dry matter yield (0.346 t/ha) and Crude
Protein (6.07%), lower in in vitro digestible organic matter (54.61% of DM) and
high in acid detergent ber (67.78%). The total ash content and metabolizable
energy (ME) were 8.96% and 8.19 MJ/kg DM, respectively. Both head and
total spermatozoa abnormalities have showed signicant variation across the
grazing period. This study demonstrated that the natural pasture dominated
with Hyparrhenia anamesa grass cannot support optimal seminal attributes,
due to both inadequate quantity and low quality of the pasture mainly during
dry period. Overall results suggest the importance of supplementation and/or
looking for other management option to enhance the reproductive per formance
of Horro rams while not further degrading pasture productivity.
Received: 02/11/2017
Accepted: 17/11/2017
Published: 24/11/2017
*For Correspondence
Abera Seyoum, Ethiopian Biodiversity
Institute, Forest and Rangeland Plants
Biodiversity Directorate, Addis Ababa,
Ethiopia, Tel: +251116612244.
E-mail: aseyum@gmail.com
Keywords: Hyparrhenia anamesa,
Agriculture, Evaluation, Protein, Organic
matter
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Res. Rev. J Ecol. Environ. Sci.| Volume 5 | Issue 4 | October - December, 2017
e-ISSN:2347-7830
p-ISSN:2347-7822
Research & Reviews: Journal of Ecology and
Environmental Sciences
of the nutritive values of grazing pasture is a paramount importance for devising the feeding strategies, which may include the
determination of supplementation [6].
However, evaluation of the nutritive value of natural pasture has got little attention and information is lacking regarding the
nutritive values of natural pastures dominated with Hyparrhenia anamesa grasses in western Ethiopia. Further, so far little work
has been done on the impact of Hyparrhenia anamesa grass on seminal traits of Horro rams. Therefore, this study was conducted
to ll this gap by evaluating the nutritive value of Hyparrhenia anamesa grass dominated natural pasture and its impacts on
seminal traits of Horro rams. We hypothesized that the nutritive value of Hyparrhenia anamesa dominated grasses deteriorates as
the dry period advanced impairing the seminal traits of Horro rams considered in this study. In consistent with our hypothesis, the
overall result indicated that hyparrhenia dominated pasture was poor in crude protein, low in biomass yield and in vitro digestible
organic matter resulting in higher head and total spermatozoal abnormalities across the grazing period.
MATERIALS AND METHODS
Study Area
The study was conducted at Bako Agricultural Technical and Vocational Education and Training (ATVET) College, West Shewa
zone of Oromia region, Ethiopia. It is located at about 250 km to the west of Addis Ababa city. The average elevation of the area
is 1560 m a.s.l. The soil type is Nitosol with a texture of sandy clay loam and receives a mean annual rainfall of 1219 mm where
a major rainfall season is during May to September [7]. The mean monthly temperature range is between 14–28°C. As in other
parts of the country, in western part general and particularly around Bako area where this research was conducted, grazing lands
play a paramount role in livestock feed and support a diverse range of grasses among which hypprehennia grass is the dominant
grass species which is less palatable, in particular during dry period, which is a challenge for livestock production in the area
where Horro breed of sheep is an integral part of farming system and predominantly a basic asset for the livelihood of the society.
Data Collection
Biomass yield and chemical analysis
One hectare of pasture land was demarcated and allocated for eighteen Horro rams for grazing. To estimate the biomass
yield of the pasture, multistage sampling system was employed. Accordingly, ve quadrates were rst established; four at the
corners and one at the center of the demarcated grazing land and the initial samples were taken. The quadrate was made of
wood with 1 m x 1 m size. Since the initial samples were taken by harvesting the pasture to the ground level, the second and third
samples were taken every month by randomly throwing the quadrate to the back side ve times at each sample taking time with in
the grazing pasture. In all cases from each entire quadrate the pasture was harvested at ground level using hand shears, weighed
and dried under the shade until constant weight is attained. The biomass yield was then estimated based on the average DM
contents of the samples for those taken at three different times. Representative dried biomass samples were grounded to pass a
1 mm sieve mesh and analyzed for DM, OM, CP and ash contents following the methods described by AOAC [8]. Neutral detergent
ber (NDF), acid detergent ber (ADF) and acid detergent lignin (ADL) were analyzed according to the methods of Van Soest PJ,
Robertson JB and Lewis BA. Metabolizable energy (ME) content of the feeds was estimated using the equation: ME (MJ/kg DM)
= 0.16 × IVDOMD [9,10]. The IV DOMD (In vitro digestible organic matter in dry matter) was determined according to Tilley JMA [11].
Semen collection and evaluation
Prior to semen collection, the temperature of the articial vagina (AV) was maintained to about 42- 45°C by lling the
space between the outer external case and the inner lining of the AV with warm water. This was supported by lling the same
cabinet with air in order to maintain pressure. The inner wall of the AV, the rst few centimeters, was also thinly lubricated with
vaseline before collection. Semen collection tubes and pipettes were also warmed at about 37°C prior to semen collection.
Ewes at estrous were made available from the ock kept in the college, and rams were exposed individually to estrus ewes for
a period of 5 minutes. After six rams were taken randomly, the semen was collected in the morning between 7:30–10:30 a.m.
at every two weeks interval for two consecutive days. Immediately after semen collection, semen volume and semen motility
were measured. The volume of the ejaculate was read to the nearest 0.1 ml directly from a graduated collection tube, and the
collection tube with semen was immediately put into water bath (about 32-34°C) for further semen evaluation. Sperm individual
progressive motility (SIM) was estimated by placing a drop of diluted semen in 3.8% sodium citrate solution under cover slip
and examined under a microscope (400x) and scored with 10% unit intervals. The percent of dead or alive spermatozoa was
computed by mixing a drop of semen sample with two drops of eosin-nigrosine stain on pre warmed clean slide. About 200
spermatozoa was then examined in different elds of the slide and categorized into colored (dead) and non-colored (alive) sperm
cells under a microscope (400 x). The percent of live spermatozoa was then calculated by deducting stained spermatozoa from
the number of counted spermatozoa and then multiplying by 100 and nally divided by total number of counted spermatozoa.
The proportion of morphologically abnormal spermatozoa was evaluated using an eosin-nigrosine smear that was prepared for
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Res. Rev. J Ecol. Environ. Sci.| Volume 5 | Issue 4 | October - December, 2017
e-ISSN:2347-7830
p-ISSN:2347-7822
Research & Reviews: Journal of Ecology and
Environmental Sciences
live/dead spermatozoa determination. About 200 spermatozoa were examined from different areas of the slide under the same
magnication. The types of abnormalities considered were head (twin, round, shrunken, large, narrow, elongated, and diminutive
heads were considered as head abnormalities), mid piece (bent, broken, and short, enlarged or thickened, double, vestigial mid-
piece) and tail abnormalities (coiled, twin, broken) as recommended by Salisbury GW [12]. These three types of abnormalities were
pooled together and reported as total abnormality of spermatozoa. Evaluation of the semen was conducted at the Veterinary
Laboratory of Bako ATVET College.
Statistical Analysis
The effect of grazing period on seminal attributes was analyzed using one-way ANOVA within R statistical program [13].
Moreover, data was further analyzed by descriptive statistics in Microsoft Excel ofce.
RESULTS
Chemical Composition of Natural Pasture
The biomass yield and chemical composition of the natural pasture is presented in Table 1.
Table 1. Chemical compositions of natural pasture.
Feed type DM yield(t/ha) DM (%) % DM* IVOMD % ME(MJ/kg DM)
Ash OM CP NDF ADF ADL
Natural
pasture 0. 346 72.33 8.96 91.04 6.07 67.78 36.9 6.14 54.61 8.19
Note: *DM= Dry matter, OM=organic matter, CP= crude protein, NDF= neutral detergent ber, ADF=acid detergent ber, ADL=acid detergent
lignin, IVOMD=in vitro organic matter digestibility, ME= metabolizable energy, MJ=mega joule
The estimated biomass dry matter yield of the natural pasture was 0.346 t/ha, while the proportion of Crude Protein, In vitro
digestible organic matter of DM and Acid detergent ber were 6.07%, 54.61% and 67.78%, respectively.
Seminal Attributes
The proportion of both spermatozoal total and head abnormalities singnicantly varied across the grazing period([ANOVA,
F (5, 30) =2.66, P=0.042), [ANOVA, F (5, 30) =6.43, P<0.001). However, Spermatozoa mid head and tail abnormalities were not
signicantly varied across the grazing period. Further, we did not found signicant differences in semen volume, sperm individual
motility, and proportion of live spermatozoa acros the grazing period.
DISCUSSION
Our study showed that the Hyparrhenia anamesa dominated pasture of the study area is poor in protein content (6.07%) and
lower in dry matter yield (0.346 t/h) and in vitro digestible organic matter (IVOMD) (54.61%). With this regards, the CP content of
the Hyparrhenia anamesa grass is below the required level of CP for animal in the tropics, i.e., 7% [14]. However, our result of CP is
greater than the CP content of 5.1% which was found during the dry season for Borana rangeland grass species [15]. This variation
may be due to differences in agro climatic conditions, forage species, and the maturity stage of the plants [16].
Moreover, the biomass production in this study was found to be 0.346 t DM/ha. This is by far below 2.25 t DM/ha for natural
pasture in Shinille zone of Somali Regional state of Ethiopia [17]. This variation may be partly attributed to the fact that samples
for biomass production was taken during the critical dry season in current study. The biomass production and nutritive values
of forage is basically crucial to meet the production and/or reproduction performance of livestock, because carrying capacity of
grazing lands should often be directly linked to the nutritive value in particularly to CP content of livestock feed consumed [18].
Furthermore, the metabolizable energy (ME) of the pasture in current study (8.19 MJ/kg) was lower than the recent report of ME
(9.69 MJ/kg) of the grazing lands natural pasture indicating that the ME content of hyparrhenia grass in this study may not be
adequate for the animals, consequently supplementation with readily available carbohydrate source is necessary to increase the
microbial biomass and rate of degradation of brous feed [19,20]. On the contrary, the proportion of neutral detergent ber (NDF)
and acid detergent ber (ADF) obtained in our result was 67.78% and 36.9%, respectively. These higher ber components of NDF
and ADF in this study could be related to the fact that the grass was over matured and dry during the experimental period, which
eventually results in increased structural carbohydrates and legnin, and decrease in protein content. The nding was consistent
with matured Digitaria grass hay fed to Wogera sheep [21]. Both head and total spermatozoa abnormalities have showed signicant
variation across the grazing period (Figures 1 and 2).
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Res. Rev. J Ecol. Environ. Sci.| Volume 5 | Issue 4 | October - December, 2017
e-ISSN:2347-7830
p-ISSN:2347-7822
Research & Reviews: Journal of Ecology and
Environmental Sciences
Note: *ah=head abnormalities, prd=period (weeks)
Figure 1. A box plot showing sperm head abnormalities of Horro rams varying across the grazing period.
1 2 3 4 5 6
10 15 20 25 30
prd
toa
Note: *toa=total abnormalities, prd=period (weeks)
Figure 2. A box plot showing Sperm total abnormalities of Horro rams varying across the grazing period.
The existence of signicant variation in head and total sperm morphological characteristics across the grazing period in the
present study may be attributed to the lower supply of CP content and IVOMD of natural pasture used that could not maintain
normal spermatozol production as the grazing period advanced towards dry season. This is in line with the phenomena where the
quantity and quality of tropical forages become more critical in the dry season imposing serious constraints to the development
and performance of livestock [22]. Moreover, sperm morphology is correlated to reproduction, as infertility is most often related to
a high proportion of structurally abnormal spermatozoa the current study suggests the necessity of supplemental feeds to support
the lower nutritive value of natural pasture in order to exploit the genetic potential of Horro rams, which further assist in proper
utilization of the grazing pasture [23].
CONCLUSION
The current study showed that the natural pasture dominated with Hyparrhenia anamesa grass species was poor in CP,
and IVOMD, but was higher in neutral detergent ber (NDF) and acid detergent ber (ADF) components. There was a signicant
variation in sperm head and total abnormalities across the grazing period. This study demonstrated that this natural pasture
cannot support optimal seminal attributes, due to both inadequate quantity and low quality of the pasture mainly during dry
period. Our overall results suggest either the importance of supplementation or other management options to compensate the
poor nutrient content of pasture and enhance the reproductive performance of Horro rams while not further degrading pasture
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Res. Rev. J Ecol. Environ. Sci.| Volume 5 | Issue 4 | October - December, 2017
e-ISSN:2347-7830
p-ISSN:2347-7822
Research & Reviews: Journal of Ecology and
Environmental Sciences
productivity.
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