Effect of Feeding Different Mixtures of Short Milled Wheat and Sesame Seed Cake on Intake, Digestibility, and Live Bodyweight Changes for Abergelle Sheep in Tigray

2.1. Experimental Animals and Feeds

Randomized complete block design with four diets and five replications was employed with 20 uncastrated yearling male Abergelle sheep with an initial body weight (18.58 ±1.9kg) (Mean±SEM) for feeding, digestion, and body weight change trials. The experimental animals were grouped into four blocks based on their initial live body weight, which was determined by two consecutive weighings after overnight fasting. Each animal in each block was randomly assigned to one of the five dietary treatments. The experimental animals were drenched with a broad spectrum anti-helmentic (Albendazole) and sprayed using acaricide against internal and external parasites, respectively. They were also vaccinated against common diseases in the area (pasteurellosis) during the adaptation period of 15 days. The experimental animals were also housed in individual pens and offered grass hay and the supplement for 15 days for adapting to the feeds prior to the beginning of the actual feeding trial. The ingredient feeds such as sesame seed cake, short milled wheat, and basal diet were purchased from local market traders and individual farmers. The feed ingredient was stacked and stored properly before and after mixing to avoid variation among the batch.

2.2. Experimental Design and Treatments

The experiment was conducted using a Randomized Complete Block Design (RCBD) with four dietary treatments that were randomly assigned to each animal in a block. Animals were blocked based on initial live weight into four blocks with five animals per block. The diets were thoroughly mixed with the proportion of 65:35 Short Milled Wheat (SMW) and Sesame Seed Cake (SSC), respectively, on a dry matter basis to achieve estimated body weight gain of 64-101g per day as recommended by Ranjhan [6]. The concentrate mixes were presented in grouped levels in 0, 120, 240, and 360 gram dry matter/head/day bases:

Diet₁ = Grass hay adlib (Control) which is 0% of short milled wheat and sesame seed cake)

Diet₂ = Grass hay adlib + 120 gram concentrate mixes (78 gram short milled wheat and 42 gram sesame seed cake)

Diet₃ = Grass hay adlib + 240 gram concentrate mixes (156 gram short milled wheat and 84 gram of sesame seed cake)

Diet₄ = Grass hay adlib + 360 gram concentrate mixes (234 gram short milled wheat and 126 gram sesame seed cake)

2.3. Feeding Trial and Managements

The supplementary feeds were thoroughly combined in the specified proportion and the actual data collection for feed utilization and growth trial was done for 90 days. The supplementary diet was offered twice per day at 8:00 and 16:00 hours in two equal portions. Animals were observed closely for the occurrence of any abnormalities and disorders during the experimental periods. Samples of feed offered and refused were collected per animal over the experimental period, pooled on a treatment basis, and sub-sampled for analysis.

2.4. Digestibility Trial

After completion of the 90-day feeding trial, the same animals with the same feeding treatment were employed for digestibility trial and feces were collected for seven consecutive days following three-day adaptation for the harnessed bag. A feces collected and weighed for each animal separately and was stored in a refrigerator at -20^oC in airtight plastic containers. At the end of the collection period, the fecal sample for each animal was thoroughly mixed and a sub-sample of a feces was made to dry in a forced air oven at 60 ^oC for 48 hours and ground to pass through a 1 mm sieve and was taken for further analysis.

2.5. Feed Intake and Live Weight Gain

The nutrient offered and refused was computed by multiplying the quantity offered and refused with their nutrient content. Daily dry matter DM intake of the sheep expressed as a percent of bodyweight was calculated by dividing daily DM intake with the respective bodyweight of each sheep used throughout the feeding trial. The experimental sheep were not allowed to graze on pasture for controlling the inappropriate factor during the experimental period. Sheep were weighed at the beginning and with an interval of fourteen days throughout the experiment following overnight fasting using a spring balance graduated of 100gm reading interval measured a balance of 50kg. Average daily gain (g/d) was calculated as the difference between final and initial bodyweight divided by the number of feeding days. Feed conversion efficiency was also estimated by dividing daily live weight gain for daily feed intake.

2.6. Chemical Analyses

A representative sample of feed provided, refused and a fecal sample was collected in every phase and analyzed for Acid Detergent Lignin (ADL), Acid Detergent Fiber (ADF), and Neutral Detergent Fiber (NDF) following the procedure described by Van Soest and Robertson [7]. Nitrogen, ash, and dry matter content were determined and CP was calculated as Nx6.25 described by AOAC [8].

2.7. Statistical Analysis

Data were Analyzed Using Analyses of Variance (ANOVA) Genstat 13^th edition SP2, (2010) computer software. Treatment means of all parameters were separated using Least Significant Difference (HSD) test. The model used for data analyses was:

Y_ij =µ+T_i +B_j +E_{i j}

Where; Y_ij = Response variable B_j = Block effect

µ= Overall mean E_ij = Random error

T_i = Treatment effect

3.1. Chemical Composition of the Experimental Feeds

The dry matter content of grass hay used in this trial (Table 1) was comparable to the DM content of 92.09 and 91.77% reported by Getachew [9] and Abebaw [10], respectively. The Crude Protein (CP) in (Table 1) value traced for hay used in the existing observation was slightly higher than the crude protein requirement (7-7.5%) of sheep for maintenance by Van Soest [11], which explained that the hay employed in the current experiment might be of good quality. The CP content of hay was comparable with a value of 6.6% reported by Simret [12]. The differences in CP content among the various studies might be attributed to the composition of the hay, environmental factors in which the curative process during harvesting season, and stage of growth at which hay was harvested [13]. Moreover, environmental factors including light intensity, precipitation and soil moisture content, soil physiochemical characteristics, mainly lime content, soil fertility, and fertilizer application significantly influence plant's nutrient content and its nutritional value for human or animal feed [14].

The high substance of NDF and ADF (Table 1) in grass hay might involve low intake. Because it is the NDF and ADF component which greatly limited the rumen gut fill and correlated with rumination time [15]. NDF was only partially digested in any species of animals and depend on microbial digestion for consuming principally the tough grass components [16]. Generally, the chemical composition of grass hay used in the experiment was higher in NDF, ADF, and ADL as compared to the values by Matiwos [17] and Michaele [18]. This might be directed that the hay used has a higher deliberation of cellulose and lignin formation of tannin-fiber complexes which could reduce nutrient availability due to the depressing effect of these portions with feed digestibility [13].

The CP content for SMW used in the trial was lower than the results by Simret [12] and Genet [19], who reported values of 19.55 and 21.23, 20.1%, but it is comparable with 14.9 and 13.8% as reported by Tesfaye [20]. The CP of sesame seed cake in the current finding was agreed with values of 37.5% and 38.5% as described by Ensminger [21] and Tesfay [22], and higher than the observation reported by Fentie and Solomon [23], but lower than the CP content of 42.21 and 43.7 as reported by Tekeba [24] and Zemichael and Solomon [25], respectively. This might be due to the variation in the capability of the method of extraction within the screw pressing process [21].

Normally, the corresponding character of nutrient content, specifically high CP and low cell wall fiber stuffing in the improvement, and low CP and high cell wall fiber contents in the basal diet could be a reason for increment in grass hay-based supplementation.

3.2. Live Bodyweight Change

In (Table 4) Contemporary significantly higher (P < 0.01) final live body weight gain was observed in the supplemented rams compared to the control group but was recorded a non-significant difference among the supplemented groups. However, increasing trend of weight gain was verified with increasing supplementation of mixed diets. This might be attributed to lower nutrient intake and digestibility of the nutrient in the control treatment, and higher dry matter and CP intake as well as better digestibility and nutrient utilization in the supplemented groups which could enhance the growth performance of individuals. Furthermore, according to the finding by Gelgelo et al. [33], there was a positive influence of supplementation on the total dry matter intake on small ruminants. Therefore, this study agreed with the results of Simret [12] and Tesfay [22] which showed that live weight change for supplemented groups across the level of supplementation did not differ significantly. Likewise, lack of significant variation among supplemented rams in live weight gain could be inferred that the supplement feeds were similar in an opportunity to contribute nutrients for improving the weight gain. Comparable to the current observation, it was indicated that a weight gain from 77.5 - 120.0 g/day for lambs fed groundnut hay as a basal diet supplemented with a mixture of different levels of rice bran and sesame cake by Njie [34]. Moreover, the level of daily live weight gain observed in this study for ram in diet4 (Table 4) is comparable to the study described by ILCA [35] for Wello sheep that gained 109 g per day on an elevated plane of dietary.

Even though there was no considerable variation in live body weight gain among the supplemented groups, in diet4, higher live body weight gain was observed than rams assigned in diet2 and diet3. Thus, increasing level of mixed diet could be reflected for higher digestibility of nutrients which was associated with live body weight gain. This might be recognized as a result of higher CP and energy content in the mixed diet. Differing from this, Fentie and Solomon [23] argued that higher amount of inclusion of sesame cakes and their higher intake by animals did not result in substantial weight gain, and the lowest mean average weight gain was recorded for animals provided a higher amount of sesame cake.

Sheep fed on grass hay alone retained a slight weight gain showed that the hay supplied satisfactory nutrient for maintenance and slight growth. This positive gain could be due to the availability of high soluble carbohydrate content in quality grass hay. However, the current finding was not in harmony with the observations by Getachew [9] and Mulu [36] who reported loss of 4 and 3 g d^-1 for Farta and Wogera sheep fed with only grass hay, respectively, which could be attributed due to the quality of grass hay used in the experiment.