Published on International Journal of Agriculture & Agribusiness
Publication Date: July 17, 2019
Sisay Kumsa, Tamirat Tasemma & Dereje Teshoma
Oromia Agricultural Research Institute, Yabello Pastoral and Dryland Agriculture Research Center P.O.Box 85, Southern Oromia, Borana, Ethiopia
The experiment was conducted at Yabello Pastoral and Dry land Agriculture Research Center with the objectives to evaluate the effect of supplementation of browses species mixed with wheat bran on feed intakes, digestibility, growth performance and carcass characteristics of Borana goats fed a basal diet of native pasture hay, and to identify the economic feasibility. The experiment was conducted using Twenty five (25) intact male yearling Borana goats with an average live weight of 15.22±0.17kg (mean and standard deviation). The experimental design was randomized complete block design five treatments with five replications. Experimental goats were blocked into five blocks of five goats based on their initial body weight (BW) and randomly assigned to one of the five treatment diets within a block. Goats were acclimatized to the treatment feeds for fifteen days. The experiment consisted of 90 days of feeding trial and 10 days of digestibility trial followed by evaluation of carcass parameters at the end of the digestion trial. Five dietary supplement treatments were T1, (63:37%) wheat bran and noug seed cake +hay adlibitum T2, 50% Vechilla tortil pod + 50% of wheat bran + hay adlibitum T3,50% of Vechilla nilotica leaf + 50% of wheat bran + hay adlibitum T4,50% of Vechilla brevispica leaf + 50% of wheat bran T5,50%mixture of three browses species)+ 50% Wheat bran+ hay adlibitum. Total dry matter intake showed significant (P<0.05) variation between treatments, highest value in T1 (722.92g/day), T2 (698.98 g/day), T3 (689.01g/day), T4 (658.90g/day) lowest in T5 (646.34g/day) respectively. Crude protein intake of the treatment diet was T1 (101.13g/day), T2 (88.2g/day), T3 (87.50g/day), T4 (85.94 g/day) and T5 (85.19 g/day) respectively. Digestibility of dry matter (DM) and organic matter (OM) were significantly different (p<0.05) where as CRUDE PROTEIN and NDF was not significant (P>0.05) the provision of supplement creates favorable rumen microbes for similar digestion of dry matter and fiber. Significance difference in apparent digestibility of crude protein and organic matter (DM) among the treatments were observed. The mean values of the average daily weight gains (ADWG) of supplemented goats were 76.2, 66.02, 63, 62.2 and 59.71g/day for T1, T2, T3, T4 and T5. The feed conversion efficiency was not significant (P>0.05) between concentrate supplement and browses species mixed with wheat bran. Partial budget analysis showed that, the highest net return (NR) was recorded high in T2 (156.39ETB/head and T4 (145.34ETB),respectively. Supplementation of browses species mixed with wheat bran resulted higher net return and marginal rate of return as compared to concentrate supplement. Generally, the present study indicated that supplementation had positive effect on performance of goat and economically viable
Keyword: Apparent Digestibility, Borana goat, Browses & Feed Conversion Efficiency.
Insufficient and poor quality of feed, particularly during the dry season, is one of the most important constraints of livestock production. The availability of feed resource depends on the quantity and distribution of the rain fall and seasonality of plant growth is a reflection of the rain fall distribution (Alemayehu, 2003). Forage availability and quality are not favorable year round and hence gains made in wet season are totally or partially lost in dry season (Alemayehu, 2004). Generally, tree fodder is richer in crude protein (CRUDE PROTEIN), minerals and digestible nutrients than grasses (Devendra, 1990 and Topps, 1992). The use of tree legume fodder as supplement has improved intake, digestibility and animal performance (Norton, 1994 and Abdulrazak et al., 1996). They provide food, medicine, fodder aside from being resistant to diseases and the harsh climatic conditions (Le Houerou, 1980).
The Borana rangeland has diverse species of woody and herbaceous plants which are useful as forage (Tolera and Abebe, 2007) wich include Vechilla brevispica, A. nilotica, A. seyal, A. tortil, Balanites aegyptiaca, Grewia bicolor, G. tembensis, Rhus natalensis, Vernonia cinerascens and grass species Cenchrus ciliaris, Chrysopogonaucheri and P. mezianum. Browse species maintain their green leaves longer into the dry season (Coppock, 1994) and are known to supply better crude protein (CRUDE PROTEIN) and minerals (Devendra, 1990; Coppock, 1994). For this reason, the use of multi-purpose trees and shrubs (MPTS) as well as agro-industrial by products as alternative sustainable feed sources for ruminants is increasingly becoming important. In this regard the use of browses species has great potential. The major use of browses species is as source of crude protein.
This quality of browses most browse species is most useful during dry season when most of the range grasses and other herbaceous species dry off (Devendra, 1990). Studies have indicated that seed pods of some Vechilla species such as Vechilla pod tortil, Vechilla albida and leaves of Vechilla nilotica, brevispica leaf when offered as supplements to poor quality roughage, give live weight gains comparable with those of livestock fed seed oil cakes and Lucerne (Medicago sativco) (ILCA, 1988; ILCA, 1989). Vechilla tortil was shown to be the Vechilla species with the highest microbial degradation potential (Ngwa et al., 2002). Vechilla leaves were reported to be a valuable source of energy and protein if harvested in the early dry season or in the wet season and stored until needed. Vechilla tortil pods at up to 75% of the diet resulted in higher dry matter digestibility;
Organic matter digestibility and body weight gain (Araya et al., 2003). The chemical component of Vechilla pod tortil in terms of crude protein and dry matter contents are 180 and 894 g/kg DM respectively. Vechilla brevispica leaf and Vechilla nilotica also contain 196, 160,824 and 980 g/kg DM crude protein and dry mater (Aster et al., 2012).
Therefore, Adding of different Vechilla species leaves and pods with concentrates in to animal feed base is believed to be minimized the feed shortage, improve the utilization of low quality feed resources and improve the animal performance during dry season. The nutritional value of these browses species on animal performance responses is not conducted in the area. Therefore, this study was conducted to evaluate feed intake, digestibility, and body weight gain of intact male Borana goats supplemented with three selected browses species mixed with wheat bran.
a. To study the effect of supplementing browses species mixing with wheat bran on digestibility, feed intake and body weight gain of intact male Borana goats fed a basal diet of natural pasture hay.
b. To assess the economic feasibility for supplementation of browses species with wheat bran mixture.
3. MATERIALS AND METHODS
3.1. Study Area Description.
The experiment was conducted at Yabello Pastoral and Dry land Agriculture Research Center (YPDARC) which is located at 564 km from Addis Ababa in Southern Borana Zone of Oromia Regional State. Yabello is located at 1350- 1800 meter above sea level(m.a.s.l.) and it is located between latitude 4°30′55.81″and 5° 24′36.39″N and longitude 7° 44′14.70″and 38° 36′05.35″E. The district covers a total area of 5426km2. Generally, the altitude of the Borana rangelands is within the range of 1000–1500m above sea level (m.a.s.l) with few hills up to 2000 m.a.s.l (Coppock 1994).
3.2. Experimental Goat and Their Management
Twenty five yearling intact male Borana goats with initial body weight (BW) 15.22 kg were bought from Yabello district. The ages of the experimental goat were estimated based on dentation. During quarantine a period of 15 days, Experimental goats were de-wormed and disinfected for internal and external parasites before the commencement of the study and individual identification (Ear tag) was given to individual. At the end of quarantine period, experimental goats were grouped into five blocks based on their initial body weight and randomly assigned to the treatment diets in a block. Experimental goats were adapted to their respective treatment for 15 days before the actual start of growth trial period. Individual pen was constructed and equipped with feeding and watering facilities.
3.3. Experimental Feed and Feeding
Hay was harvested from Yabello Research Center and used as basal diet during experimental period. Hay of natural pasture was harvested manually at optimum maturity stage/at flowering stage of growth, dried, baled and stored in hay shade to maintain its quality. To prevent bleaching that may happen during drying; the harvested grass was turned up frequently and dried within two to three days. Basal diets were chopped to a length of about 2-5cm to minimize wastage and selection. Supplemental feeds used were Vechilla tortil pod, Vechilla nilotica, Vechilla brevispica, Noug cake and wheat bran. Noug cake wheat bran adequate for the entire feeding period was purchased from Yabello town. Vechilla brevispica leaf, Vechilla tortil pods and Vechilla nilotica leaf was collected from mature plants when maturity is attained. Leaves are hand harvested by pruning the lower branches from its twigs on plastic sheet by using stick through pulling. The trimmed leaves were spread thinly on plastic sheet under shade and turn regularly to ensure uniform drying for 2-3 days and stored in plastic bag for future. The supplement diets are offered twice per day morning and evening in separate trough to that of basal diet. The amount of basal diet (on DM basis) was given and clean drinking water once per day and mineral (salt) provided free choice to each goat during the entire feeding period.
3.4. Experimental Design and Treatment Layout
The experimental animals were grouped into five blocks of five animals each based on their initial body weight that was determined by taking the averages of two consecutive weights after overnight fasting at the end of the quarantine period. Animals in a block were randomly assigned to one of the five experimental treatments. Thus, there were five animals per treatment. The basal diet natural grass hay was fed to all animals ad libitum and supplemental feeding was on DM basis. Supplementary treatments (T1-T5) were estimated to supply above 55 g/day CRUDE PROTEIN and body weight to achieve estimated body weight gain of 50 g per day as recommended by Ranjhan (2001) and body weight of animals.
Treatment 1=37% of Noug cake + 63 % wheat bran + hay adlibitum
Treatment 2=50% of VPT + 50% of wheat bran + hay adlibutum
Treatment 3=50% of VN + 50% of wheat bran + hay adlibutum
Treatment 4=50% of VBL + 50% of wheat bran + hay adlibutum
Treatment 5=50% of MBS + 50% Wheat bran+ hay adlibutum
VPT=Vechilla pod tortil, VPL=Vechilla brevispica leaves, VNL=Vechilla nilotica leaves, MBS=mixture three browse species.
3.5. Feed Intake
Feed offered to experimental goat and corresponding refusals were weighed and recorded daily throughout the experimental period. Sub-samples of feeds offered and refusal were pooled across the experimental period for each animal. The composite refusal samples were pooled per treatment. Feeds and refusal samples were placed in air-tighted plastic bags and stored in an appropriate place to chemical analysis. The daily dry matter and nutrient intakes of the goats were calculated as a difference between that offered and refused. Feed conversion efficiency was estimated as a ratio of daily body weight gain per units of feed consumed daily. Daily total dry matter intake calculated as follow.
Total dry matter (DM) intake (percent body weight) =DM intake (g)/body weight*100…1
Total DM intake (metabolic body weight (g/kgW0.75) =DM intake (g)/BW0.75 (kg)……….2
3. 6. Live Weight Change
The body weight of each experimental goat was measured at the beginning of the experiment and at 10 days intervals during the experimental period. At the end of feeding trial the final body weight of goats were measured. Average daily body weight gain was calculated as a difference between final and initial body weight of the goats divided by the number of experimental days. Feed conversion efficiency of the goats was determined as the proportion of daily body weight gain to the total daily dry matter (DM) intake according to Gulten et al.,(2000) as follow(equation 4).
Where: ADWG= Average Daily Weight Gain, IBWG= Initial Body Weight Gain and
TNFD= Total Number of Feeding Days, FBW =Final Body Weight
Where FCE=feed conversion, DWG=Daily weight gain, TDMI=total dry matter intakes
3.7. Digestibility Trial
At the end the feeding trial, all animals were made to adapt carrying the fecal bags for 3 days followed by total collection of faeces for 7 days. The faeces collected every day from each animal were weighed, thoroughly mixed, 10% sampled and stored in a refrigerator at -20°C. The faeces sampled for 7 days were pooled for each animal, thoroughly mixed and then 10 % sub-sampled for chemical analysis. The sub samples of the faeces were dried at 60oC for 48 hrs. The dried sample of faeces were be ground pass through 1 mm sieve and stored in air tight polyethylene bag until analyzed. The apparent digestibility coefficient (DC) of nutrients is calculated by using the equation below (McDonald, 2002):
Apparent digestibility coefficient=(Total nutrient consumed- Total nutrient in faeces)*100—6
Metabolized energy intakes of goats from experimental feeds were estimated by using the equation:
Where: DOMD=digestible organic matter
3.8. Feed Chemical Analysis.
Chemical analysis of feed offered and refusal in both digestibility and growth trial and faeces in digestibility trials were carried out by taking the representative sample. The sample of feed offered and refused was taken to Holleta Research Center dried in oven to constant weight of 60oc for 48 hours in forced air draft oven for partial dry matter determination. The partial dried sample of feed and faeces were milled using laboratory mill to pass l mm screen. Dry matter (DM) organic matter (OM) and crude protein (CRUDE PROTEIN) of the offered and refused feeds were determined according to AOAC procedure (AOAC, 1990). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) in feed samples were analyzed according to Vansoest and Robertson procedure. The crude protein (CRUDE PROTEIN) content is estimated as N X 6.25.
3.9. Partial Budget Analysis
Partial budget analysis was calculated based on cost of wheat bran, Noug cake, labor cost feed, leaf collection, animal purchase and average sale price of the goat at the local market. The net return calculated from total revenue and total variable cost obtained from the sale of goat. By simple mathematical calculation, the net return obtained by subtracting change in return from total variable cost. The partial budget analyses were performed to evaluate the economic advantages of the different treatments by using the procedure of (Upton, 1979). Average market price used to find out the market values for the different treatment groups. The profit analyzed using the following equation.
Where, NI = net income; TR = total return and VC = variable cost.
The marginal profit of goat fattening was calculated from the increase in change net income (ΔNI) that can be generated by each additional unit of expenditure (VC)
Where, MRR=Marginal rate of return, NI=Net income, VC=Variable cost
3.10. Statistical Analysis
General linear model procedures of SAS (2002). The treatment means were separated by least significant difference (LSD). The model used for data analysis:
Where: Yijk = response variable; μ = overall mean;
Ti = treatment effect, Bj = block effect; = random error
4. RESULT AND DISCUSSION
4.1. Chemical Composition of Feed Experiment
The Chemical Composition of the feeds and experimental diet used in the present study is given in Table 1. The CRUDE PROTEIN content of the hay used in this study was not similar to the CRUDE PROTEIN content of good quality grass hay (11%) reported by McDonald (2002), and not within the range of 7.5-15.45% reported for natural pasture hay (Solomon et al., 2008).
However, the crude protein (CRUDE PROTEIN) content of hay used in this study was higher than the CRUDE PROTEIN content of 5.6% and 4.2% reported by Getachew (2005) and Mulu (2005) respectively, but, comparable with the value of 6.56% reported by Simret (2005). The variation of crude protein content of hay may be due to nutrient content of the soil, stage of maturity, harvesting season, types grass, management of hay and climatic condition of the area.
The crude protein content of the natural pasture hay used in this study was 6.44% indicating that it has no a potential to support the maintenance requirements of goats. Hay which contains a minimum of (7%) crude protein needed to support acceptable ruminal microbial activity and the maintenance requirement of the host ruminant (Van Soest, 1994). Therefore, natural pasture hay used in the present study can categorized as poor quality and cannot fulfill the maintenance requirement of goats.
The NDF content of hay used in this study (70.8%) was less than the value of 76.75% and 75.68% and reported by Mulu (2005) and Jemberu (2002); but comparable with the value of 70.7% and 71.8% reported by Asnakew (2005) and Getachew (2005), respectively. Feeds that contain high proportion of ADF have lower availability of nutrients due to ADF being negatively correlated with feed digestibility (McDonald et al., 2002). The result of the chemical analysis of hay used in this study was characterized by its high DM, NDF, ADF and low CRUDE PROTEIN contents.
The crude protein content of Noug cake in current study lower than the crude protein reported by McDonald (2002), but similar with crude protein reported by Seyoum (1995) which is 23.9 and 26.8 respectively. However, it was lower than the result reported by Bhuyane et al. (1996) and Temesgen(1995) with values of 41.02 and 44.5% respectively. The Variation might be due to the effect of processing factory and the quality of the seed used in the factory.
The organic matter contents concentrate feeds in the present study such as wheat bran, Noug cake and concentrate mixture was 96.66, 89.95 and 92.81%, respectively. The acid detergent fiber content of wheat bran was comparable to 12.70 and 12.45% reported by Solomon et al. (2004 and Jemberu (2008), respectively but lower than 15.50 Hirut (2008) and higher than 9.49 reported by Giri (2000)
Dry matter, organic matter, acid detergent fiber, neutral detergent fiber and crude protein content of Vechilla nilotica was not comparable with the values 13.1% and 15.4% reported by Aster et al., (2012) during dry and rainy season. Dry matter, organic matter, and acid detergent fiber, neutral detergent fiber, crude protein content of Vechilla brevispica leaves of current study was similar with the values of 19.6% reported by Aster (2012), during rainy season. Vechilla brevispica leaf has higher value of acid detergent fiber and lower neutral detergent fiber compare to Aster et al. (2012) which is 19.1 and 31.8% respectively. The dry matter, organic matter, acid detergent fiber, neutral detergent fiber and crude protein content of Vechilla tortil pods agreed with the values of 17.78% reported by Aster et al. (2012). The value of ADF and NDF of current study was higher than that value of 15.47 and 21.76% DM reported by Aster et al., (2012) respectively.
4.2. Dry Matter and Nutrient Intake
The mean daily dry matter and nutrient intake of the experimental goats during the feeding trial were given in table 2. There was a significant difference (P<0.001) among treatments in natural pasture hay intakes and total dry matter intakes. All supplemented treatment was readily consumed by goat without refusal. Therefore, there is no significance difference (p>0.05) on supplemented treatment. Hay of natural pasture intake and total dry mater intakes were greater (P<0.001) for T1 and T2 then T3, and values for T4 was greater than T5 (P<0.001). There is no significance difference of hay intake between T2 and T3, T5 and T4. The result of current study was indicated that the dry matter intake of hay greater for the concentrated (362.91g/day) than supplemented wheat bran mixed with browses species in which intermediate dry matter hay intake was recorded in treatment two (T2) and three (T3) 338.98 vs. 329.01g/day and lowest intake was observed in treatment four (T4) and five (T5) which was 298.90 vs. 286.34g/day respectively. This variation might be depending on voluntary feed intakes of animals. But, the amount of hay intakes reduced through the experimental period due to increased amount of supplementation after ten days interval due to the adjustment made following of their weight. Crude protein content of natural pasture hay refusal was lower than the offered hay which indicate that goats has the ability to select more nutritious part of feed. Whereas, the content of organic matter, acid detergent fiber and neutral detergent fiber higher than the offered hay. Total dry matter intake different among treatment which it followed similar trend like that of natural hay dry matter intakes intake.
Therefore, total dry matter intake of goat in treatment one (T1) 722.91g/head per day found significantly higher (P<0.001) than those received browses species mixed with wheat bran. Becholie et al. (2005) also reported that supplementation with a protein source (tagasaste) increased total DM, OM and CRUDE PROTEIN intakes in lambs fed on a basal diet of grass hay. Similar finding was reported by Girma et al.(1994) in which sheep fed maize Stover supplemented with legumes and legumes plus concentrate mixture showed significantly higher total DM intake. Abou El-Nasr et al. (1994) reported that concentrate supplementation improved roughage intake, nutrient digestibility and utilization in sheep. Similarly, goat in treatment in T4 and T5 had the lowest total dry matter intake (658.90 vs. 646.34 g/day/head) (P<0.001) as compared goat supplemented treatment T2 and T3 (698.98 vs. 689.67g/day) this due to the amount of hay intake.
Accordingly, the values of total dry matter intake observed in this study was (646.34-722.91/day) within the range of values of 434.8-753.3g/d reported by Ermias (2008) for sheep fed a basal diet of faba bean haulms and supplemented with barley bran, linseed meal and their mixtures. The current total dry matter intake T1 (concentrate supplement) higher than the finding of (M.M.Rahman et al., 2013) which was 668g/day goat supplemented palm kernel cake and higher than concentrate supplement (584g/day). Therefore, the current result summarized that browses type has a significant effect on total dry matter and nutrient intakes.
Protein intake among the different treatment groups was significantly different (p< 0.001) which could be attributed to variations in hay intake and supplement. A highest crude protein intake was observed in treatment T1, T2, T4, T3 and T5. Among the supplemented treatments, animals on concentrate supplementation had higher (P<0.001) crude protein intake than browses leaf/pods mixed with wheat bran, while the crude protein intake of the browses with wheat bran mixture supplemented goat was similar T2 and T4 at (P>0.05). Ranjhan (1997) indicated that a 20 kg sheep require 85g CRUDE PROTEIN to meet its nutrient requirement for growth. According to this recommendation, CRUDE PROTEIN intake 85.98-101.113g/day of goats in all treatment is in surplus of that needed for maintenance and the target average daily gain.
The total DM intake based on percent body weight (%BW) were not significant different (P>0.05) among the supplement. The daily DM intake based on (3.11-3.28% BW) of goat in this experiment is within the range of 2.6 to 3.2% reported for Small East African goat and their crosses with Norwegian goat fed hay and supplemented with concentrate (William et al., 2013).
4.3. Apparent Dry Matter and Nutrient Digestibility
Apparent dry matter (ADM) and nutrient digestibility coefficient of Borana goats fed hay basal diet and supplemented with browses species mixed with wheat bran is presented in table 3. There is no significant difference (P>0.05) among the treatment on apparent digestibility of dry matter (DM), acid detergent fiber (ADF), neutral detergent fiber (NDF) of experimental diet. Simret (2005) confirmed that the apparent digestibility of NDF and ADF were similar between goats fed on grass hay basal diet and wheat bran-peanut cake mixture supplemented treatments. The apparent digestibility of dry matter in the current study was recorded within the ranges of (63-66). This finding lower than Arsi Bale goat feed dried mulberry leaf reported by Dereje (2014) within the value of (68.4-71.3). It may be due to the species and nutrient intakes.