Effect of dietary inclusion of babul pods (Acacia nilotica) in concentrate mixture on haemato-biochemical, rumen fermentation parameters and faecal egg count in growing Osmanabadi goats

Introduction

Goat farming constitutes an integral component of smallholder livestock production in India, providing livelihood, meat, and milk to millions of farmers. Osmanabadi goats (Capra hircus Linnaeus), indigenous to the Marathwada region of Maharashtra, are a hardy, dual-purpose breed well-suited to agro-pastoral systems. Escalating costs of conventional feed ingredients and the increasing problem of gastrointestinal parasitism in small ruminants have collectively necessitated exploration of locally available, cost-effective, and bio-functionally beneficial alternative feed resources (Chaudhari et al., 2022) [1] . Babul pods (Acacia nilotica Willd. ex Delile), a leguminous tree resource of arid and semi-arid India, contain moderate levels of condensed and hydrolysable tannins, which exhibit anthelmintic, antimicrobial, and protein-protection properties relevant to small ruminant health (Makkar, 2003) [2] . The haemato-biochemical status of ruminants is a critical indicator of metabolic health and nutritional adequacy. Tannin-containing diets can influence haemoglobin synthesis and serum protein levels through the protein protection effect of condensed tannins, which form stable protein-tannin complexes in the rumen, increasing the supply of ruminally undegraded protein to the small intestine (Parthasarathi et al., 2018) [3] . Rumen fermentation is sensitive to dietary tannin levels; condensed tannins at moderate concentrations reduce total volatile fatty acid and ammonia nitrogen production and modify microbial community structure (Bhatta et al., 2009; Rira et al., 2019) [4,5] . The anthelmintic properties of condensed tannins against gastrointestinal nematodes are well documented, with significant reductions in faecal egg count reported following supplementation with tannin-rich forages (Nguyen et al., 2005; Max, 2010; Paswan et al., 2016) [6,7,8] . However, data on the haemato-biochemical, rumen fermentation, and faecal egg count responses of the indigenous Osmanabadi breed to dietary babul pods are lacking. The present study was therefore undertaken to evaluate the effect of dietary inclusion of Acacia nilotica pods at 15 and 25% in the concentrate mixture on haemato-biochemical parameters, rumen fermentation profile, and faecal egg count in growing Osmanabadi goats.

Materials and methods

Experimental animals, site, and design

The experiment was conducted at the Department of Animal Nutrition, College of Veterinary and Animal Sciences (COVAS), Maharashtra Animal and Fishery Sciences University (MAFSU), Parbhani, Maharashtra, India during 2023-24 for 90 days following a 15-day acclimatization period. Eighteen growing Osmanabadi goats (9 males and 9 females, aged 4-5 months, mean initial body weight 12.95 ± 0.36 kg) were randomly allocated to three equal groups (n = 6 each; 3 males + 3 females) in a completely randomized design after anthelmintic treatment with albendazole (10 mg/kg body weight): T 0 -control total mixed ration without babul pods; T 1 -total mixed ration with 15% babul pods in concentrate; T 2 -total mixed ration with 25% babul pods in concentrate. Animals were individually housed. Ethical approval was obtained from the Institutional Animal Ethics Committee, COVAS, MAFSU, Parbhani.

Experimental diets and feeding management

Mature fallen pods of Acacia nilotica were shade-dried, ground with seeds using a Willey mill, and stored in airtight bags. Three isonitrogenous concentrate mixtures (Table 1) were formulated and supplied at 30% of the total mixed ration on an as-fed basis along with 50% jowar kadbi and 20% Hybrid Napier as per (ICAR) [9] norms. Crude protein of all concentrate mixtures was uniformly 21.60% on dry matter basis. Total mixed ration was offered twice daily with quantities adjusted fortnightly. Proximate composition was determined as per (AOAC) [10] .

Haematological parameters

Blood samples (4 ml each) were collected by jugular venepuncture at monthly intervals (days 0, 30, 60, and 90). One ml was transferred into ethylene diamine tetraacetate vacuum tubes and the remaining 3 ml into clot activator tubes; serum was stored at -20 °C.

Haemoglobin was determined by the acid-hematin technique and packed cell volume by the Wintrobe microhaematocrit technique (Jain, 1986) [11] .

Serum biochemical parameters

Serum total protein was estimated by the Biuret method (Kaneko, 1980) [12] at 578 nm. Albumin was measured by the bromocresol green endpoint method (Dumas et al., 1971) [13] at 630 nm. Globulin was calculated by subtraction. Blood urea nitrogen was analysed by the Berthelot method (Kaneko et al., 2008) [14] . Aspartate aminotransferase and alanine aminotransferase were estimated using a semiautomatic biochemical analyser and expressed as IU/l.

Rumen fermentation parameters

Approximately 75 ml of rumen liquor was collected 2 h post-feeding at trial end using a hand suction pump and Ryle's stomach tube. Rumen pH was measured immediately with a digital pH meter. Total volatile fatty acids were estimated by Markham's steam distillation (Barnett et al., 1957) [15] and expressed as mEq/100 ml. Titratable acidity was estimated as per (Rosenberger) [16] . Total nitrogen was estimated by micro-Kjeldahl method (AOAC, 2023) [10] and expressed as mg/100 ml.

Faecal egg count

Fresh faecal samples were collected directly from the rectum at monthly intervals and processed by the McMaster floatation technique. Eggs counted under one chamber were multiplied by 100, or two chambers by 50, to obtain the egg per gram value.

Statistical analysis

Data were analysed by one-way analysis of variance in a completely randomized design as per (Snedecor and Cochran) [17] . Significance was considered at p < 0.05.

Results and discussion

Proximate composition of feedstuffs and total mixed rations

The proximate composition of babul pods (Acacia nilotica) on dry matter basis was: dry matter 93.16%, organic matter 95.64%, crude protein 16.60%, ether extract 4.21%, crude fibre 15.10%, nitrogenfree extract 59.73%, and total ash 4.36% (Table 2). All three concentrate mixtures were isonitrogenous (crude protein 21.60% dry matter) and the three total mixed rations showed comparable composition (crude protein uniformly 11.30% dry matter), confirming that observed treatment differences were attributable to babul pod inclusion and associated tannins rather than differential nutrient supply.

Haematological parameters

The haemoglobin and packed cell volume values of growing Osmanabadi goats are presented in Table 3. The overall mean haemoglobin for T 0 , T 1 , and T 2 were 10.51 ± 0.22, 10.59 ± 0.21, and 10.73 ± 0.20 g/dl, respectively, with non-significant (p > 0.05) differences. At all monthly intervals, haemoglobin values remained within the normal physiological range of 8-14 g/dl for goats. Similarly, the overall mean packed cell volume for T 0 , T 1 , and T 2 were 30.37 ± 0.27, 30.47 ± 0.27, and 30.70 ± 0.32%, respectively, with non-significant (p > 0.05) differences, all within the normal range of 22-38%. Maintenance of haemoglobin and packed cell volume within normal limits indicates that dietary tannins at these levels did not adversely affect erythropoiesis or iron utilization. (Mousa) [18] reported similar findings in Awassi lambs fed Acacia at up to 40%. (Paswan et al.) [19] found only slight, non-significant effects on haemoglobin in Black Bengal kids fed babul pod meal. (Dey et al.) [20] similarly reported that haemoglobin and packed cell volume remained similar across dietary groups in lambs supplemented with condensed tannins from Ficus infectoria (Roxb.) leaves. The numerically higher haemoglobin and packed cell volume in T 2 may reflect greater erythrocyte stability due to the antioxidant properties of polyphenolic compounds in babul pods (Olafadehan, 2011) [21] .

Serum biochemical parameters

The monthly serum biochemical values are presented in Table 4. Serum total protein showed a significant (p < 0.05) increase in T 2 at all monthly intervals and in the overall mean (T 0: 6.31 ± 0.06; T 1: 6.70 ± 0.06; T 2: 6.89 ± 0.05 g/dl), with T 2 significantly higher than T 0 and T 1 intermediate. This elevation is consistent with the protein-protection mechanism of condensed tannins, which form stable proteintannin complexes in the rumen, reducing microbial degradation of dietary protein and increasing the supply of ruminally undegraded protein to the small intestine (Makkar, 2003) [2] . (Parthasarathi et al.) [3] reported significantly (p < 0.05) higher serum total protein in Deccani ram lambs fed tanniferous diets, and (Uguru et al.) [22] noted significant (p < 0.05) differences in serum total protein in Red Sokoto goats fed Acacia nilotica pods. Serum albumin levels were 3.52 ± 0.07, 3.52 ± 0.06, and 3.61 ± 0.04 g/dl for T 0 , T 1 , and T 2 , respectively, with non-significant (p > 0.05) differences, all within the normal range of 2.4-3.8 g/dl. Globulin values (T 0: 2.80 ± 0.07; T 1: 3.18 ± 0.09; T 2: 3.27 ± 0.05 g/dl) showed non-significant (p > 0.05) differences. The albumin:globulin ratio values were 1.28 ± 0.05, 1.13 ± 0.04, and 1.11 ± 0.02 for T 0 , T 1 , and T 2 , respectively (p > 0.05), within normal limits. Blood urea nitrogen values (T 0: 16.53 ± 0.32; T 1: 16.39 ± 0.39; T 2: 16.20 ± 0.35 mg/dl; p > 0.05) showed a declining trend, indicating that condensed tannins facilitated greater tissue-level nitrogen utilization and reduced ruminal ammonia absorption (Olafadehan, 2011) [21] . Serum glutamic oxaloacetic transaminase (T 0: 41.38 ± 0.57; T 1: 42.01 ± 0.47; T 2: 42.27 ± 0.63 IU/l) and serum glutamic pyruvate transaminase (T 0: 20.60 ± 0.56; T 1: 21.18 ± 0.61; T 2: 21.62 ± 0.46 IU/l) were non-significant (p > 0.05) and within normal limits, confirming the absence of hepatotoxic effects at these dietary levels (Mousa, 2011; Paswan et al., 2017) [18,19] .

Rumen fermentation parameters

The rumen fermentation data are presented in Table 5. Total volatile fatty acid concentrations for T 0 , T 1 , and T 2 were 16.23 ± 0.41, 15.27 ± 0.67, and 13.79 ± 0.69 mEq/100 ml, respectively, with T 2 significantly (p < 0.05) lower than T 0 . Titratable acidity (T 0: 19.36 ± 0.61; T 1: 18.36 ± 0.63; T 2: 16.12 ± 0.53) was significantly (p < 0.05) reduced in T 2 compared to both T 0 and T 1 . Total nitrogen was significantly (p < 0.05) lower in T 2 (74.04 ± 1.37 mg/100 ml) than in T 0 (80.74 ± 1.01). Rumen pH (T 0: 6.16 ± 0.05; T 1: 6.26 ± 0.07; T 2: 6.40 ± 0.10) showed a consistent increasing trend but non-significant (p > 0.05) differences, all values within the normal range of 5.5-7.5 for ruminants. The significant reductions in total volatile fatty acids and titratable acidity in T 2 are consistent with the inhibitory effect of condensed tannins on rumen microbial fermentation (Bhatta et al., 2009) [4] . (Rira et al.) [5] reported that hydrolysable tannins from Acacia nilotica pods significantly (𝑝 < 0.05) reduced total volatile fatty acid production. The significant reduction in total nitrogen reflects condensed tannin-mediated inhibition of rumen proteolysis and deamination, reducing ammonia nitrogen production (Yang et al., 2016; Ebong, 1995) [23,24] . The maintenance of normal rumen pH across all groups confirms that tannin content at these inclusion levels did not disrupt rumen buffering capacity, in agreement with (Santra and Karim) [25] .

Faecal egg count

The faecal egg per gram values are presented in Table 6. The overall mean egg per gram values for T 0 , T 1 , and T 2 were 383.33 ± 52.70, 266.67 ± 27.89, and 141.67 ± 23.86, respectively. A significant (p < 0.05) and progressive reduction was observed with increasing babul pod inclusion, with all three groups differing significantly (T 0 >T 1 >T 2 ), and T 2 achieving a 63.04% reduction compared to the control. The significant reduction in faecal egg per gram is attributed to the anthelmintic properties of condensed tannins, which precipitate infective larvae of gastrointestinal nematodes, inhibit larval development and exsheathment, impair establishment of adult worms, and reduce worm fecundity (Nguyen et al., 2005) [6] . (Paswan et al.) [8] reported significant (p < 0.01) reduction in egg per gram in goats fed Acacia nilotica pod meal. (Max) [7] observed significant (p < 0.01) reductions in faecal egg counts in sheep and goats supplemented with tannin-containing plants. The anthelmintic effect is particularly valuable given increasing anthelmintic drug resistance among Haemonchus contortus in small ruminants in India (Paswan et al., 2017) [19] . In contrast, (Kahiya et al.) [26] found non-significant reductions in goats fed 40% Acacia nilotica leaves, likely due to differences in tannin form and nematode species involved.

Conclusion

The dietary inclusion of babul pods at 15 and 25% in the concentrate mixture of growing Osmanabadi goats did not adversely affect haematological parameters or hepatic safety markers, all of which remained within normal physiological limits throughout the trial. Serum total protein was significantly improved in the 25% inclusion group, indicating enhanced bypass protein utilization mediated by the protein-protection properties of condensed tannins. Rumen fermentation was modulated in a dose-dependent manner, with significant reductions in total volatile fatty acid production, titratable acidity, and total nitrogen without disruption of rumen pH, while a significant, progressive reduction in faecal egg count demonstrated meaningful anthelmintic activity. These findings collectively support the safe and beneficial incorporation of babul pods up to 25% in the concentrate mixture of growing Osmanabadi goats, with particular implications for sustainable parasite management and improvement of protein nutrition in smallholder goat production systems.

Tables

Acknowledgement

AcknowledgmentsThe authors gratefully acknowledge the institutional resources and support provided by the Department of Animal Nutrition, College of Veterinary and Animal Sciences, Maharashtra Animal and Fishery Sciences University, Parbhani, Maharashtra, India, which funded this research. The authors also thank the technical and field staff of the Department for their assistance during the trial.

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