Effects of Urea-Treated Sorghum Stover on Growth Performance, Nutrient Digestibility, Haematology and Serum Biochemistry of West African Dwarf Grower Bucks

1Introduction

Goat production contributes to household food supply, income generation and livelihood security in Nigeria. The West African Dwarf (WAD) goat is particularly important in humid and sub-humid areas because of its adaptability and suitability for smallholder production systems (Daramola et al., 2005). Nevertheless, productivity may be constrained by seasonal shortages of good-quality forage and dependence on fibrous agricultural residues (Devendra, 2013; FAO, 2023).

Sorghum stover is a locally available crop residue that can contribute to ruminant diets, but its feeding value is limited by structural fibre, low nitrogen content and relatively poor digestibility when untreated (Sundstøl and Owen, 1984). Urea treatment is used to improve the utilization of fibrous residues. During treatment, urea hydrolysis releases ammonia, which can alter plant cell-wall associations and improve access to structural carbohydrates by rumen microorganisms (Van Soest, 1994). The extent of the response depends on treatment conditions, diet composition and the balance between available nitrogen and fermentable energy (Fazaeli et al., 2006; Sarnklong et al., 2010).

Assessment of a feed intervention should extend beyond growth alone. Body-weight change, feed intake and feed conversion describe productive response, while apparent digestibility indicates the proportion of consumed nutrients not recovered in faeces (Daramola et al., 2005). Haematological indices provide information on blood-cell status, and serum biochemical measurements can help describe protein and nitrogen metabolism and selected enzyme activities. These indicators therefore provide complementary evidence when evaluating the suitability of treated crop residues for growing goats (McDonald et al., 2022).

This study examined growth performance and nutrient digestibility, and haematological and serum biochemical indices, in WAD grower bucks fed varying levels of urea-treated sorghum stover. The objective was to identify the inclusion level associated with the most favourable overall response under the reported experimental conditions.

2Materials and methods

2.1Experimental site, animals and management

The experiment was conducted at the Oyo State College of Agriculture and Technology, Igboora, Oyo State, Nigeria. Fifteen healthy WAD grower bucks aged 6–7 months, with an average initial body weight of approximately 6.8 kg, were sourced from a farm within Igboora. The animals underwent a 14-day acclimatization period before the feeding trial. They were managed under similar housing conditions, treated against internal and external parasites according to the source project reports, housed in well-ventilated pens and provided clean drinking water ad libitum.

2.2Experimental design and dietary treatments

The animals were allocated randomly to five dietary treatments in a completely randomized design, with three animals per treatment. Treatments consisted of sorghum stover treated with 0%, 1%, 2%, 3% or 4% urea and were designated T1, T2, T3, T4 and T5, respectively. Each treatment group received its assigned sorghum stover alongside a basal concentrate diet. Feed was offered twice daily, with the quantity described in the source documents as approximately 5% of body weight.

2.3Preparation of urea-treated sorghum stover and basal concentrate

Sorghum stover was collected after harvest, air-dried and chopped. For each treatment, 5 kg of stover was treated with the assigned quantity of urea dissolved in 5 L of water: 0 g for T1, 50 g for T2, 100 g for T3, 150 g for T4 and 200 g for T5. The solution was distributed evenly over the stover and mixed. The material was placed in covered plastic containers and allowed to ferment for 28 days. After opening, the treated stover was exposed to air briefly before feeding.

The composition of the basal concentrate diet is given in Table 1.

Ingredient	Inclusion (%)
Cassava peel	45.00
Wheat offal	26.00
Palm kernel cake	17.50
Groundnut cake	8.00
Bone meal	2.50
Salt	1.00
Total	100.00

Calculated nutrient composition: crude protein 11.32%; crude fibre 9.08%; metabolizable energy 2,405.85 kcal/kg.

2.4Feeding trial and growth measurements

The feeding trial lasted 28 days after acclimatization. Feed offered and refusals were measured daily; daily intake was calculated as feed offered minus feed refused. Body weight was measured at the start and at weekly intervals. Total weight gain was calculated as final minus initial body weight, average daily gain as total gain divided by 28 days, and feed conversion ratio as total feed intake divided by total weight gain.

2.5Digestibility trial

A seven-day digestibility trial followed the feeding trial, with an adaptation period reported in the source project. Each buck was housed individually in a metabolism cage. Feed offered, refusals and daily faecal output were recorded. Representative feed, refusal and faecal samples were pooled, oven-dried at 65°C, ground through a 1-mm sieve and stored for proximate analysis. Apparent digestibility was calculated from nutrient intake and the corresponding nutrient recovered in faeces.

2.6Blood collection and laboratory analyses

At the end of the 28-day feeding period, approximately 5 mL of blood was collected from each buck through the jugular vein. Samples for haematology were placed in labelled tubes containing EDTA. Samples for serum biochemistry were collected in plain tubes, allowed to clot, centrifuged at approximately 3,000 rpm for 10–15 minutes, and the serum was stored at about −20°C until analysis. Haematological measurements included packed cell volume (PCV), haemoglobin (Hb), red and white blood cell counts (RBC and WBC), platelet count, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and differential leukocyte counts. Serum measurements included total protein, albumin, globulin, albumin:globulin ratio, blood urea nitrogen (BUN), creatinine, glucose, AST, ALT, ALP and cholesterol. The source projects report the use of an automated haematology analyser and standard biochemical methods/reagent kits.

2.7Statistical analysis

The source studies report analysis of variance (ANOVA) using SAS (2002), followed by Duncan’s Multiple Range Test to separate treatment means at the 5% significance level (P < 0.05). Results are presented as reported in the source tables, including standard errors of the mean (SEM) and reported P-values where available.

3Results and discussion

3.1Growth performance and nutrient digestibility

Table 2 shows that dietary treatments significantly affected the growth performance, feed intake, and feed conversion efficiency of WAD grower bucks (P < 0.001). T₂ (1% inclusion) recorded the highest total weight gain (0.53 kg), average daily weight gain (18.93 g/day), and weekly weight gain (132.50 g/week), alongside the lowest FCR (21.45). T₃ (2% inclusion) had the highest feed intake (12.43 kg), while T₅ (4% inclusion) recorded the lowest (10.28 kg). T₂ (1% inclusion) recorded the highest weight gain and most favourable feed conversion ratio, consistent with findings by Mijinyawa et al. (2024), Akinbode et al. (2021) and Hyelda et al. (2017). Table 3 shows that urea-treated sorghum stover significantly influenced nutrient digestibility in WAD grower bucks. T₄ (3% inclusion) recorded the highest dry matter (72.97%) and crude protein (78.59%) digestibility. T₃ (2%) had the highest crude fibre (74.58%) and carbohydrate (83.28%) digestibility, while T₁ (0%) recorded the highest ether extract digestibility (75.59%). T₂ (1%) had the highest ash digestibility (72.81%). Urea treatment can improve nitrogen availability and fibre degradation, although its effectiveness depends on inclusion level and dietary energy balance (Van Soest, 1994; Woyengo et al., 2004; McDonald et al., 2022). T₄ (3%) recorded the highest dry matter and crude protein digestibility, while T₃ (2%) had the highest crude fibre and carbohydrate digestibility, supporting findings by Mertens (2002) and Okeniyi et al. (2021).

Parameters	T₁ (0%)	T₂ (1%)	T₃ (2%)	T₄ (3%)	T₅ (4%)	SEM	P-value
Initial weight (kg)	7.65a	6.80b	6.90b	6.67b	6.04c	0.23	0.01
Final weight (kg)	7.68a	7.33b	7.22b	6.75c	6.49d	0.19	0.001
Total weight gain (kg)	0.03d	0.53a	0.32c	0.08c	0.45b	0.07	0.001
Average daily weight gain (g/day)	1.07e	18.93a	11.43c	2.86d	16.07b	2.50	0.001
Weekly weight gain (g/week)	7.50e	132.50a	80.00c	20.00d	112.50b	17.50	0.001
Feed intake (kg)	11.75b	11.37c	12.43a	10.93d	10.28e	0.32	0.001
FCR (feed intake/gain)	391.67a	21.45c	38.84c	136.63b	22.84c	18.25	0.001

Means within the same row with different superscript letters differ significantly (P < 0.05). SEM, standard error of the mean; FCR, feed conversion ratio.

Parameter (%)	T₁ (0%)	T₂ (1%)	T₃ (2%)	T₄ (3%)	T₅ (4%)	SEM	P-value
Dry matter digestibility	70.13a	65.44b	68.67a	72.97a	68.42a	1.23	0.05
Crude protein digestibility	71.57b	59.92c	64.61bc	78.59a	67.19b	3.18	0.01
Crude fibre digestibility	71.46a	65.36b	74.58a	73.97a	72.90a	1.66	0.05
Ether extract digestibility	75.59a	42.10c	64.80b	58.00b	51.20bc	5.82	0.05
Ash digestibility	48.21b	72.81a	39.22c	49.29b	49.21b	5.59	0.05
Carbohydrate digestibility	78.28ab	63.14c	83.28a	81.90a	76.89b	3.58	0.01

Means within the same row with different superscript letters differ significantly (P < 0.05). SEM, standard error of the mean.

3.2Haematological and serum biochemical indices

Table 4 shows that urea-treated sorghum stover significantly affected all haematological parameters (P < 0.05). T₂ (1% inclusion) recorded the highest PCV, haemoglobin, RBC, WBC, platelet count, MCV, MCH, MCHC and lymphocyte percentage. T₁ (0%) had the lowest PCV and MCHC, while T₄ (3%) recorded the lowest MCV, MCH and lymphocyte percentage and the highest neutrophil percentage. Monocyte percentage was highest in T₃ and T₅, while eosinophil percentage was highest in T₁. The results in Table 5 indicate that varying levels of urea-treated sorghum stover significantly affected all measured serum biochemical parameters (P < 0.05). T₁ (0% inclusion) recorded the highest total protein, albumin, AST, ALT, glucose and cholesterol values. T₅ (4%) had the highest ALP activity (302 U/L) and blood urea nitrogen (14.0 mg/dL), while T₂ (1%) recorded the highest creatinine concentration (1.6 mg/dL). T₄ (3%) had the lowest total protein, albumin, A:G ratio, AST, ALT, glucose and cholesterol values.

Serum biochemical responses varied across treatments, with the control recording the highest total protein, glucose and cholesterol, while T₅ (4%) recorded the highest blood urea nitrogen and ALP. These biochemical variations are consistent with reports by Okpanachi et al. (2019), Ibhaze et al. (2021), Afolayan et al. (2024), Oduye et al. (1976), Jiwuba et al. (2022), Plumb (1999), Ahmad et al. (2012) and Tawose et al. (2024). Haematological parameters were most favourable at T₂ (1%), which recorded the highest PCV, haemoglobin, RBC, WBC, platelet count, MCV, MCH and lymphocyte percentage. Similar dietary effects on blood indices have been reported by Wuanor and Carew (2018), Daramola et al. (2005), Chineke et al. (2006), Soul et al. (2019) and Idowu et al. (2026). Further supporting evidence was reported by Ibhaze et al. (2021), Jiwuba et al. (2022) and Afolayan et al. (2024), indicating that blood responses do not necessarily improve as treated-stover inclusion increases. Therefore, 1% inclusion produced the most favourable growth, feed conversion and haematological responses, whereas 2–3% improved the digestibility of selected nutrients, demonstrating the importance of appropriate inclusion and dietary balance.

Parameter	T₁ (0%)	T₂ (1%)	T₃ (2%)	T₄ (3%)	T₅ (4%)	SEM	P-value
PCV (%)	20c	33a	28b	22c	20c	2.47	0.014
Hb (g/dL)	6.3c	10.9a	9.2b	7.1c	6.6c	0.82	0.011
RBC (×10⁶/µL)	8.4c	13.1a	12.3b	10.2bc	9.1c	0.88	0.015
WBC (×10³/µL)	63.95b	96.60a	64.50b	44.15c	43.85c	9.69	0.019
MCV (fL)	23.81	25.19	22.76	21.57	21.98	0.65	0.017
MCH (pg)	7.50	8.32	7.48	6.96	7.25	0.23	0.020
MCHC (%)	31.50	33.03	32.86	32.27	33.00	0.30	0.021
Platelets (×10³/µL)	124b	166a	119b	106c	120b	10.07	0.016
Lymphocytes (%)	56c	64a	60b	55c	58bc	1.53	0.013
Neutrophils (%)	37a	32b	34b	40a	36ab	1.35	0.017
Monocytes (%)	2ab	1a	3b	1a	3b	0.45	0.019
Eosinophils (%)	5a	3b	4ab	4ab	4ab	0.32	0.019

Means within the same row with different superscript letters differ significantly (P < 0.05). SEM, standard error of the mean; PCV, packed cell volume; Hb, haemoglobin; RBC, red blood cells; WBC, white blood cells; MCV, mean corpuscular volume; MCH, mean corpuscular haemoglobin; MCHC, mean corpuscular haemoglobin concentration.

Parameter	T₁ (0%)	T₂ (1%)	T₃ (2%)	T₄ (3%)	T₅ (4%)	SEM	P-value
Total protein (g/dL)	7.8a	7.3c	7.6b	6.8d	7.6b	0.17	0.015
Albumin (g/dL)	3.5a	3.2c	3.4b	2.7d	3.3bc	0.14	0.018
Globulin (g/dL)	4.3a	4.1b	4.2ab	4.1b	4.3a	0.05	0.034
A:g ratio	0.8a	0.7b	0.8a	0.6c	0.7b	0.04	0.027
Ast (U/L)	236a	171c	220b	169c	224b	13.48	0.013
Alt (U/L)	143a	121c	132b	99d	133b	7.07	0.012
Alp (U/L)	121b	53d	84c	91c	302a	42.77	0.014
Creatinine (mg/dL)	1.2ab	1.6a	1.1b	0.9c	1.1b	0.12	0.022
Bun (mg/dL)	4.2d	12.8bc	13.7ab	11.4c	14.0a	1.78	0.016
Glucose (mg/dL)	65a	60bc	62b	57c	61bc	1.32	0.019
Cholesterol (mg/dL)	126a	115b	120ab	78c	119ab	8.39	0.015

Means within the same row with different superscript letters differ significantly (P < 0.05). SEM, standard error of the mean; AST, aspartate aminotransferase; ALT, alanine aminotransferase; ALP, alkaline phosphatase; BUN, blood urea nitrogen; A:G ratio, albumin:globulin ratio.

4Conclusion

The study concluded that urea-treated sorghum stover influenced the growth performance, feed utilization, nutrient digestibility, haematological and serum biochemical parameters of West African Dwarf grower bucks. T₂ (1% inclusion) produced the highest weight gain, most favourable feed conversion ratio and best overall haematological response. T₃ (2% inclusion) recorded the highest feed intake and improved crude fibre and carbohydrate digestibility. The variations in serum biochemical indices indicated differences in protein, nitrogen and energy metabolism across the dietary treatments. Overall, urea-treated sorghum stover can serve as an alternative feed resource for WAD grower bucks, with 1% inclusion showing the most favourable overall response under the conditions of this study.

5Recommendations

Based on the reported outcomes, 1% urea-treated sorghum stover may be considered for WAD grower bucks under conditions comparable to those of the present study, with appropriate management and a balanced basal diet. This should be treated as a provisional recommendation rather than a universal optimum. Further trials should use larger numbers of animals, longer feeding periods and replicated measurements of growth, digestibility, blood indices and clinical health. Future reports should include the full statistical output, clear reference intervals for blood parameters, and an economic assessment of feed cost per unit of weight gain. The urea-treatment protocol should also be described precisely and consistently, including the basis for expressing inclusion percentage, moisture conditions and airing period before feeding.

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