Response of Sheep to Dietary Soybean Haulms: Effect on Growth, Serum Indices and Oxidative Biomarkers Profile

Background and Objective: Utilization of crop residue in complete diets of ruminants may be a sustainable alternative for enhanced profitability in production. This research assessed the performance of sheep-fed dietary soybean haulms in a complete diet with or without garlic powder. Materials and Methods: Sixteen rams were divided into three treatment groups in a completely randomized design and assigned to three treatment diets as follows: Control (no soybean haulms inclusion), SHD (30% inclusion of soybean haulms) and SHGD (30% inclusion of soybean haulms+0.5% inclusion of garlic). The animals were managed on experimental diets for 77 days. Data collected on feed intake, weight changes, feed conversion ratio, hematological parameters and serum indices were subject to one-way analysis of variance using the GLM procedure of SPSS (version 23). Results: It indicated that weight changes, feed intake and FCR were not affected (p>0.05) by feeding 30% soybean haulms to sheep in complete diets with or without garlic powder. However, total protein, packed cell volume, hemoglobin, MCV, MCH and uric acid were reduced in the treatment group fed soybean haulms. The addition of garlic in a soybean haulms-based diet did not influence (p>0.05) the effects observed by the inclusion of soybean haulms. All other hematological parameters, blood metabolites and oxidative biomarkers were not affected (p>0.05) by the addition of soybean haulms in the complete diet of sheep. Conclusion: As 30% soybean haulms can be included in the complete diet of sheep as alternative feedstuff. Including soybean, haulms may also improve the animal’s antioxidant capacity by reducing uric acid.


INTRODUCTION
There has been a continued search for cheap alternative sources of feed ingredients other than feeding human-edible materials to animals and the use of arable land to produce animal feed instead of producing human-edible food directly for sustainable ruminant production 1 . This calls for concerted efforts towards identifying feed ingredients with less competition with man and monogastric animals that are also readily available in commercial quantities. Crop residues remain available as cheap alternative sources because they are left to waste on farms without further processing. During feed scarcity, especially in dry seasons, crop residue forms a significant part of the maintenance diet for livestock. The residues may be obtained at no cost from most smallholder farms after crop harvest or can be gotten at very little cost 2 .
Using crop residues in animal diets could also address the problem associated with burning them on the farm, constituting environmental hazards. Also, using crop residues in livestock feed will improve the products along the value chain of the individual crops. One available crop residue that could be explored in the nutrition of ruminants is the soybean haulms.
Soybean haulms consist of the husks of the pods with leaves and tender stems remaining as by-products after harvesting the seeds of pulses 3 . Soybean haulms are an abundant and renewable form of biomass with enormous potential as a low-cost feed and a sustainable source of energy 4 . While the availability of the haulms is promising, their utilization by ruminants may be challenged due to the poor nature of crop residues. Unlike other feedstuff available for ruminant production, crop residues usually has low crude protein, energy and micronutrients with high cell wall constituents like lignin and silica 5 . This makes them less palatable, hence, the characteristic low voluntary intake by animals and low digestibility. All these have limited their use in ruminant feeding regimes. Given the preceding, processing and strategic combination of soybean haulms in a complete diet may improve its quality and utilization in the diets of ruminants 6 .
A feeding system that combines soybean haulms and other feedstuff to form a concentrate may be a useful strategy for utilizing crop residue in feeds due to its fibrous nature. Such a strategy will increase intake and improve feed utilization and subsequently, animal production performance. This strategy could also employ feed additives with the potential to modulate the rumen environment for efficient performance. Hence, efforts to assist the animals in utilizing these low-grade feedstuffs more efficiently are key to economically enhancing livestock productivity.
Garlic may help improve the efficiency of nutrient utilization in ruminants. This is because garlic and its products have been reported to modulate rumen fermentation for improved utilization of feed 7 . Garlic supplements reduced CP degradability and increased the total VFAs 7 . These results suggest that the supplementation of garlic product would be the best in improving propionate production and reducing NH 3 -N and acetate to propionate ratio. It is important to note that these strategies in improving the utilization of soybean haulms as ruminant feedstuff should ensure improved performance, physiology and oxidative status of the animals, hence, the study was designed to assess the growth performance, hematological parameters, serum indices, blood minerals and oxidative biomarkers of sheep fed complete concentrate diets containing soybean haulms and garlic powder.  inclusion of garlic) as shown in Table 1. All animals on arrival were quarantined for 6 weeks before the commencement of the experiment. The animals were treated for possible bacterial infection using PenStrep® (1 mL/10 kg). They were also treated for ecto and endo parasites using Ivermectin® Blood collection and analysis: At the end of the experiment, about 5 mL of blood was collected via the jugular vein of the animals using needles and syringes. After collecting, 2 mL of the blood was emptied into sample bottles containing anticoagulant (EDTA) to prevent clothing for subsequent analysis of haematological parameters. The remaining 3 mL was emptied into sample bottles without anticoagulant. Thereafter, the blood sample was centrifuged and serum harvested for analysis of serum indices, minerals and antioxidant parameters. The parameters measured include: Total protein, albumin, glucose, total cholesterol, triglycerides, lipids, uric acid, MDA, glutathione peroxidase, sodium, potassium, chloride, calcium, packed cell volume, red blood cells, white blood cells etc. Red blood cells, white blood cells and lymphocytes were evaluated with the help of an automatic blood analyser (ADVIA 120, Bayer, USA) according the method described in Stanworth et al. 10 , while packed cell volume (PCV) was determined as described in Stephen et al. 11 using the microhaematocrit method, hemoglobin (Hb) was determined as described in Nkrumah et al. 12 using cyanmethemoglobin method. The procedure for plasma glucose concentration determination is mentioned in Abdalla and Abdelatif 13 using a kit (Spinreact, S.A., Spain). Serum triglyceride and cholesterol, LDL and HDL were measured using a biochemical analyzer (Olympus Au 400 system autoanalyzer) according to Babaeenezhad et al. 14 . The procedure described in the report of Afele et al. 15 was used for the determination of blood minerals and serum antioxidants.

Statistical analysis:
The results of growth indices, haematological parameters, serum indices, serum minerals and oxidative biomarkers were analysed using one-way analysis of variance as contained in the general linear models procedures of SPSS (version 23) as described in Ikyume et al. 16 with individual sheep serving as the experimental unit. Significant differences among treatment means where applicable were separated at a probability level of 5% (p<0.05).

Growth response of sheep to dietary soybean haulms with/without garlic powder:
The result of the growth performance of sheep to dietary inclusion of soybean haulms in complete feed was shown in Table 2. All growth indices measured were not affected (p>0.05) by the inclusion of soybean haulms with/without garlic powder in the diet. However, the inclusion of garlic in soybean haulms based diets showed marginal improvement (p>0.05) in growth indicators compared to feeding only soybean haulms. This was as marginal decreases (p>0.05) were observed in growth indices in the soybean haulms based diets compared to the control.

Haematological indices of sheep in response to dietary soybean haulms with/without garlic powder:
The result of haematological indices of sheep in response to dietary soybean haulms with/without garlic powder was provided in Table 3. Packed cell volume decreased (p<0.05) in soybean haulms based diets with/without garlic powder (29.00 and 27.75%, respectively) compared to the control diet (38.25%). A similar trend as in packed cell volume was seen in haemoglobin concentration, mean corpuscular volume and mean corpuscular haemoglobin. Haemoglobin was higher (p<0.05) in the control diet (12.75 g dLG 1 ) compared to the other soybean haulms with/without garlic powder based diets (9.68 and 9.25 g dLG 1 for SHD and SHGD, respectively). Mean corpuscular volume and mean corpuscular haemoglobin values were higher (p<0.05) in the control diet (64.05 fl and 21.33 pg, respectively) compared to the soybean haulms based diets with or without garlic powder. Other haematological indices evaluated were not affected (p>0.05) by the inclusion of soybean haulms with or without garlic powder in the diet. Table 4 represented the result of serum indices of sheep in response to dietary soybean haulms with/without garlic powder. Total protein concentration in the blood reduced (p<0.05) in the soybean haulms diets with or without garlic powder (5.40 and 5.23 mg dLG 1 , for SHD and SHGD, respectively). However, the albumin, glucose, cholesterol, triglyceride and lipid profile of the rams were not affected (p>0.05) by the addition of soybean haulms with or without garlic powder in the diet.

Oxidative biomarkers and blood metabolites of sheep fed a complete diet containing soybean haulms with/without garlic powder:
The result of oxidative biomarkers and blood metabolites of sheep fed a complete diet containing soybean haulms with/without garlic powder was indicated in Table 5. All oxidative stress biomarkers except uric acid were not affected (p>0.05) by the addition of soybean haulms with or without garlic in complete diets of sheep. Uric acid decreased (p<0.05) in soybean haulms with/without garlic powder compared to the control. The control diet had a value of 6.85 g mLG 1 of uric acid while values of 5.75 and 5.68 mg mLG 1 were observed for SHD and SHGD, respectively. All blood metabolites were not affected (p>0.05) by the inclusion of soybean haulms with/without garlic powder in the diet of sheep.     Means with different superscript along the same row are significantly (p<0.05) different, Control: No soybean haulms inclusion, SHD: 30% inclusion of soyabean haulms, SHGD: 30% inclusion of soyabean haulms+0.5% inclusion of garlic and SEM: Standard error of mean      Means with different superscript along the same row are significantly (p<0.05) different, Control: No soybean haulms inclusion, SHD: 30% inclusion of soyabean haulms, SHGD: 30% inclusion of soyabean haulms+0.5% inclusion of garlic and SEM: Standard error of mean

DISCUSSION
Using crop residue in complete diets for ruminants has become essential for sustainable livestock production. Soybean haulms inclusion in sheep diets did not adversely affect the performance of the animals. The similar growth indicators observed at the inclusion of soybean haulms in a complete diet at 30% compared to the control diet (without soybean haulms) indicate that the haulms could be viable feed resources for feeding ruminants. Adu and Osuhor 17 reported that yearling red Sokoto goats fed complete diets at the 40 and 50 levels of soybean haulm inclusion had better total feed intake, live weight gain and feed efficiency than when soybean haulms were fed solely. Similar to the findings of this report, the feed conversion ratio in sheep remained unchanged when soybean straw replaced hay in the diet of yearling male intact Gumuz sheep 18 .
On the contrary, dry matter intake improved with a 20% inclusion of soybean hay in the diets of goats compared to control as against the similar results for feed intake obtained in this report 19 . The level of inclusion of soybean haulms and the species of animals would have accounted for the differences in dry matter intake in these two reports. It should be noted, however, that the addition of garlic powder (rumen modulator) as a feed additive to improve utilization of soybean haulms in sheep did not impact significantly on the growth indicators.
Nutritional studies should ensure the welfare and health of animals if such feed management strategies are sustainable. The trend observed in the reduction in packed cell volume (PCV), hemoglobin (Hb) concentration, mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) is evident in the significant and consistent relationship found between PCV and Hb concentration. Although there was a reduction in PCV and Hb in diets containing soybean haulms, the values obtained were within the normal range of 27-45% and 9-15 g dLG 1 , respectively, reported Radostits et al. 20 for clinically healthy sheep. The reduction in PCV and Hb in this study did not indicate the presence of an active erythropoiesis condition, given that such an effect may not have impacted the animals with similar values of MCHC obtained across all treatment groups. Also, similar lymphocyte and neutrophil counts observed in this study are suggestive that the soybean haulms diets did not contain toxic substances such as pesticide poisoning to warrant a reduction in hemoglobin and packed cell volume. On the contrary, higher PCV hemoglobin was observed in sheep fed a mixed ration of crop residue 21 . The type of crop residue utilized and the mixture could have accounted for the differences in that report and the current study.
This current study suggested that decreased total protein in sheep may indicate the lower digestive efficiency of coarse roughage by sheep. Yami and Merkel 22 reported that sheep have less digestive efficiency for coarse roughage compared to other ruminants. This effect of possible lower digestive efficiency was also not remedied by adding garlic powder to the diet, as similar crude protein concentrations were observed in both SHD and SHGD, respectively.
Even though the concentration of serum uric acid (UA) in each individual may be affected by a number of factors including genetics, body weight and lifestyle, diet and its purine content can also affect its concentration in the blood. Compared to the control, the reduction in uric acid in soybean haulm-based diets may be due to relatively low purine content associated with low-protein content in crop residue.
Soybean haulms may contain other favorable components in reducing urate in the animals. This is good for the animal's well-being, given that reduction in uric acid implies improved antioxidant capacity.
The use of varying levels of soybean haulms in the diet of sheep could ascertain the level to which this feed ingredient could be utilized in ruminant feeding. Further research will be required on the use of different levels especially levels above the one used in this current research.

CONCLUSION
Including soybean haulms in the complete diet of sheep at 30% will be a viable alternative feed resources for the animal. Soybean haulms reduced plasma uric acid in sheep, which indicates improved animal antioxidant capacity. The addition of garlic powder in a complete diet containing 30% soybean haulms did not improve the sheep's performance.

SIGNIFICANCE STATEMENT
The utilization of soybean haulms in a complete diet may be a sustainable alternative to a ruminant feeding system. This study has established that dietary 30% inclusion of soybean haulms in complete diets maintained growth performance and physiological status of sheep with possible improvement in the antioxidant status of the animals. The addition of garlic powder at 0.5% did not further improve the utilization of soybean haulms by the sheep. The study has established that soybean haulms could be an alternative feedstuff for sheep feeding systems.