Supplemental value of leaf based concentrates with Panicum maximum hay on performance of West African dwarf goats

A study was conducted to evaluate the effects of supplementation of a leaf based concentrate consisting of a 1:1 leaf mixture of Vernonia amygdalina and Tithonia diversifolia (VATD) as a direct replacement for brewers dried grains (BDG) on feed intake, growth performance and digestibility by West African Dwarf (WAD) goats on a basal diet of Panicum maximum hay. Twenty five growing WAD goats weighing between 8.07 9.60 kg were allotted into five dietary treatment groups in a completely randomized design with five goats per treatment. The mixed leaf meal (VATD) were included in the diets at 0% (T1), 5% (T2), 10% (T3), 15% (T5), and 20% (T5) of the total diet. The experiment lasted for twelve weeks. Results showed that dry matter (DM) intake (g/kg W 0.75 /day) was lowest (P<0.05) in control diet T1 (72.02), and higher in T3 (92.78) than T2, T4 and T5 (88.69, 86.61 and 86.70, respectively). Crude protein (CP) intake (g/kg W 0.75 /day) peaked at T3 and progressively reduced thereafter in T4 (15.10), T5 (14.83) and T2 (14.16). CP intake was higher (P<0.05) in T3 than T1. Daily weight gain (g/day) of goats ranged from 32.97 (T4 and T5) to 38.40 (T3). Crude protein digestibility was higher (P<0.05) in T5 (89.49%) than T1 (84.23%) and T4 (84.19%) but similar in T2 (85.47%) and T3 (86.10%). Better nitrogen intake (15.10 g/day) was observed in goats fed T4 compared to those fed T1 (14.32) and T2 (14.16). Rumen pH values were higher in T1 than T2, T3, T4 and T5. Ammonia N content (mg/100ml) of the rumen was similar in goats fed T2 (9.92), T3 (10.07) and T5 (9.80) but higher (P<0.05) than those fed T1 (8.19). The result suggests that WAD goats fed VATD leaf meal based concentrates perform better on diets with levels of mixed concentrates not exceeding 10%.


INTRODUCTION
Utilizing the vast amount of grasslands in Nigeria remains one of the most economical ways to achieve growth in ruminant production.However, these grasses and pastures are deficient in nitrogen and digestible nutrients *Corresponding author.E-mail: tayeabegunde@yahoo.com.Tel: +2348032521212.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License for optimum fermentative rumen digestion (VanSoest, 1982).Consequently, this results in low intake which can be improved by tree fodder supplementation (Topps, 1992;Abdulrazak et al., 2000).According to Kanjanapruthipong and Leng (1998), there was an improvement in the performance of rams fed poor quality grass diets supplemented with Gliricidia maculata at an optimum level of inclusion of 20 -25%.Similarly, Tona et al. (2014) reported improved intake and live weight gains when they fed concentrate diets with graded levels of Moringa oleifera leaves at 15% level of inclusion to goats.Tree browses have tremendous potential as supplements to the low quality forages or grass diets fed to goats.Most tree browses, however, contain tannins that may adversely affect their utilization (Makkar et al., 1989;Makkar, 1993).It is therefore important to process forages to remove the anti-nutrients.Different processing methods used to remove anti-nutrients from forages include wilting, air drying, sun drying, and oven drying.Where tannin contents have been reduced through processing to a tolerable level, the tannin may proffer a by-pass characteristic to the protein, hence making it utilizable by the animal (Aganga and Tshwenyane, 2003;Barry and McNabb, 1999).
Wild sunflower (Tithonia diversifolia) is one of the new foliages, which is considered by many to be a valuable green manure.In Western Kenya, it is renowned as a component of agro-forestry systems as it is rich in N, P and K, which are essential for soil fertility.According to the reports of Mahecha and Rosales (1996), the crude protein content in the foliage of T. diversifolia was 24.2% on DM basis and about 40% of the protein was soluble.The percentage of NDF (on DM) was 35.3 and 30.4% ADF.The rumen degradable protein (in sacco) was about 90% in 48 h (Rosales, 1996).The low content of tannins reported for Tithonia foliage (Wambui et al., 2006) supports the idea that the protein may well be highly soluble with poor "bypass" characteristics (Preston and Leng, 1987).The fact that loss of nitrogen in the urine was higher for Tithonia than for Calliandra or Sesbania (Wambui et al., 2006) supports this suggestion and further reveals that rumen ammonia levels are high in Tithonia, resulting in high excretory levels of urea in the urine.A high proportion of N released in the rumen could contribute to higher N retention if it is fed in combination with high tannin foliage in the diet (Barry, 1987).
Bitter leaf (Vernonia amygdalina) is a shrub with petiole leaf of about 6mm diameter, green with a characteristic odour and bitter taste.It is propagated vegetatively while growing under a range of ecological zones in Africa and produces large mass of forage and is drought tolerant (Bonsi et al., 1995).Although the leaves are used for human consumption, its production outweighs its human consumption suggesting that the excess may be utilized as feed for ruminants without detrimental effects on general productivity of animals.Presence of tannins was reported in the forages of Bitter leaf (Daodu and Babayemi, 2009).This situation suggests that the foliage of V. amygdalina could confer bypass properties on the ruminal protein derived from T. diversifolia leaves.
The objective of this study was to examine the effects of supplementation of concentrates containing 1:1 leaf mixture of V. amygdalina and T. diversifolia on voluntary feed intake, diet digestibility and growth performance for growing West African Dwarf goats fed a basal diet of Panicum maximum hay.

Study site and animal management
This study was conducted at the Goat Unit, Teaching and Research Farm, Institute of Agricultural Research and Training, Moor Plantation, Ibadan, Nigeria.Twenty-five (25) female growing West African Dwarf (WAD) goats of approximately 6-7 months old and weighing between 8.50 -9.60 kg were used for the study.The goats were housed intensively in well ventilated individual pens in an open sided housing unit, which had previously been cleaned and disinfected with morigard solution before the arrival of the animals.They were administered with Pestes des Petit Ruminants vaccine, broad spectrum antibiotics (Kepro-oxytet 20% LA injection) and ivomec ® to eliminate possible ecto-and endoparasites.The floor of each pen was covered with wood shavings as bedding material.Animals were allowed a 2-week adaptation period during which they were introduced to free feeding of compounded concentrates and P. maximum forages.At the end of the adaptation period, animals were randomly divided into five dietary treatments of five animals per treatment balanced for weight.

Feeding trial
Concentrate diets were fed in the morning (08.00h) and P. maximum hay in the afternoon (14.00 h).Fresh water was provided ad libitum.Block of saltlick was permanently placed in each pen.During the first two weeks, animals were served 200 g of concentrate diet and 300 g of P. maximum hay allowing a proportional refusal of 10% of total daily amount offered (Ondiek et al., 2010).Refusals were collected daily, weighed and recorded.Animals were weighed before the commencement of the experiment and then weekly for 12 weeks.Each weighing was done after 10-12 h withdrawal of feed.

Digestibility study
Digestibility trial was carried out by the total faecal and urine collection method of McDonald et al. (1995).Immediately after 12 weeks of the feeding trial, animals were weighed and each animal was penned in an individual cage for 14 days, with a 7 day adjustment and another 7 days collection period.Faeces and urine voided were collected.Individual total urine was collected and a 10% aliquot was kept in a refrigerator (0-4°C) for analysis.Faecal samples wrapped in aluminium foil were dried at 65 0 C for 48 h, milled and stored in air-tight bottles until analyzed.During the last three days of the digestibility trial, approximately 10 ml of rumen liquor was collected from the goats before feed was offered and thereafter 2, 4, 6 and 8 h post feeding, using a stomach tube.The pH of the sample was determined immediately using an ionizable pH meter and the sample was thereafter strained through a double layer of clean cheesecloth.About 10 ml of the liquid fraction was sampled, acidified with 2 ml of 10% H 2 SO 4 and stored in a refrigerator for analysis of NH 3 -N (Han et al., 1989).

Chemical composition
Chemical composition (Crude protein, Ether extract, Ash and Dry matter) of P. maximum hay, V. amygdalina, Tithonia diversifolia and the experimental diets were determined according to the methods of AOAC (1990).Neutral detergent fibre (NDF), Acid detergent fibre and Lignin components of the diets were determined according to the procedure of VanSoest et al. (1991).

Statistical analysis
All data collected were subjected to analysis of variance (ANOVA) using the procedure of SAS (1999).Significant treatment mean values (p<0.05) were compared using the Duncan Multiple Range Test of the same package.

RESULTS AND DISCUSSION
The chemical composition (g/100 g DM) of P. maximum, V. amygdalina, T. diversifolia and compounded diets is shown in Table 1, while  Odedire and Oloidi (2014) for T. diversifolia were higher than values observed in this experiment.Genetic differences (variety), stage of maturity and location (Osuga et al., 2006) may have resulted in the differences in chemical composition.The CP content of P. maximum (11.28) fell within the range (105 to 133 g/kg DM) reported for tropical grasses (Topps and Oliver, 1993) and higher than 7.63 (Yousuf et al., 2007) for P. maximum.CP value for P. maximum (11.28 g/100 g DM) is higher than 7% indicated as the minimum for microbial growth and optimum roughage intake (Marschner, 1995;Minson, 1981).The high crude protein of the grass could be attributed to the young age of the grasses at the time of harvest (Most were about 4-6 weeks at the time of harvest).Marschner (1995) reported that at any nitrogen rate, the nitrogen concentration in emergent leaves and newly expanded leaf lamina was higher than in mature leaf lamina.Plants transfer nitrogen to younger tissues, which import higher amounts of nutrients than they export prior to reaching maturity.NDF content of diets increased (41.69 -55.26 g/100 g) with a corresponding increase in the level of VATD meal it contained while the content of ADF also increased from 23.48 -28.56 g/100 g in the concentrate diets.The increase in NDF and ADF as inclusion level of leaf meal   increased could be attributed to the high cell wall constituents usually present in leaf meals (Ambrasu et al., 2004).The higher CP value and lower NDF, ADF and ADL in both V. amygdalina and T. diversifolia compared to P. maximum presents the two forages as adequate in ruminant nutrition.
Table 3 shows the performance characteristics, pH and rumen ammonia of WAD goats fed T. diversifolia and V. amygdalina leaf based concentrates.Dry matter (DM) intake (g/kg W 0.75 /day) was lowest (P<0.05) in control diet T1 (77.02), and higher in T3 (92.78)than T2, T4 and T5 (88.69, 86.61 and 86.70, respectively).This trend of DM intake revealed an initial increase in intake till it peaked at 10% VATD leaf meal inclusion level and then a decrease.This trend was consistent with the reports of Abdu et al. (2014) where DM intake of Zizypus mauritiania leaf meal based diet progressively increased till the 10% inclusion level and then decreased.However, the findings in this study does not support the reports of Ondiek et al. (2010) who reported a progressive increase in DM intake as leaf meal (Maerua angolensis and Zizyphus mucronata) inclusion in the diet increased.DMI values ranging from 54.60 to 59.60 g/kg 0.75 for WAD goats on groundnut hay basal diets, and offered moringa and bamboo foliages as supplements were reported by Asaolu et al. (2010).Higher intake in the leaf meal containing diets supports the hypothesis that there are benefits in feeding mixtures of forages on DM intake and digestibility (Asaolu et al., 2012).The high intake associated with the 10% leaf meal diet suggests positive associative effect of the components of the leaf meal at that level of inclusion.
CP intake (g/kg W 0.75 /day) was significantly (P<0.05)higher in T3 (16.07)than T1 (13.20), showing a peak at T3 and progressively reducing thereafter in T4 (15.10) and T5 (14.83).In an earlier study (Vranic et al., 2009), intake in ruminants was also influenced by a taste related factor-palatability.However, apart from nutritional composition, animals tend to consume more of palatable diet (Ibeawuchi et al., 2002).VATD leaf meal is not a very palatable feed ingredient due to its bitter taste.Increasing levels of VATD leaf meal mixtures in the diets may explain why the VATD leaf meal diets intake reduced after Treatment 3. The bitter taste, however, did not prevent animals consuming the leaf meal based diets to perform better than the control.Meanwhile, among the VATD leaf meal diets, Treatment 3 may have yielded the best-synchronized release of nitrogen and carbohydrate (Silva and Orskov, 1985) in the rumen required for microbial protein synthesis.This may have influenced the observed superior dry matter intake for goats on Treatment 3. NDF intake (g/kg W 0.75 /day) was lowest (P<0.05) in T1 (49.30) and highest (P<0.05) in T3 (64.31).These values also exhibited the same trend as the DMI (Dry Matter Intake) and CPI (Crude Protein Intake) where increase in values terminated at Treatment 3 followed by a progressive decrease.The NDF intakes, when converted to g/day (361.92-397.75) were similar to NDF intake values of 325.9 -347.10 reported by Oni et al. (2013) for WAD goats fed ensiled cassava leaves with or without molasses and caged layer waste.Weight gain (g/d) of goats was significantly affected by the treatment.Goats fed T3 (10%VATD meal) had significantly (P<0.05)higher weight gain (38.40 g) than those fed T1 (35.49g), T4 (32.97 g) and T5 (32.97 g).This observation was expected since protein supplementation and intake is directly proportional to weight gain (Shahjalal et al., 1997).Earlier work (Negesse et al., 2001) observed increased Average Daily Gain in Saanen kids with the diet containing 17.6% CP when compared with 14.4, 11.4 and 8.7% CP levels.Likewise, (Shahjalal et al., 1997) reported that growth rate of grazing Black Bengal goats can improve under conditions of increased protein supplementation.Weight gain (g/day) of goats observed in this study (32.97 -38.40) were higher than values (-4.91 -17.4) reported by Ondiek et al. (2010) for growing small east African goats fed Rhodes grass hay supplemented by 1:1 mixture of M. angolensis and Z. mucronata leaf browses.
Rumen pH in all treatments was similar except for the control where it was higher.Rumen pH is an important factor that measures the alkalinity and acidity of rumen contents (Cabrita et al., 2006).Okoruwa et al. (2014) reported that for optimum rumen microbial fermentation, the rumen pH should lie between 6.00 and 6.80.However, all values reported for pH in this study fall below 6.00 except for the control (6.15) but this did not translate into reduction in weight gain as may be expected.Reduced rumen pH in the present study may be due mainly to reduced proteolysis, degradation of peptides and deamination of amino acids in the rumen.Reduction in pH between the control diet and other diets could probably be attributed to the crude protein contributed by the leaf meals in the concentrate diets since there was a gradual decrease in crude protein level in diets as more VATD leaf meal replaced brewers' dried grains.
Ammonia N content (mg/100 ml) of the rumen was similar in goats fed T2 (9.92), T3 (10.07) and T5 (9.80).Rumen NH 3 -N values for goats in T4 (10.75) were higher (P<0.05)than those fed T1 (8.19).Ammonia N values (8.19 -10.75 mg/100 ml) observed in this study compared favourably with values (8.99 -12.70) reported by Ondiek et al. (2010), but lower than values reported for goats fed guinea grass and different levels of avocado seeds with orange peels (Okoruwa et al. (2014).The most suitable rumen NH 3 -N concentration levels for microbial activities range between 5 and 20 mg/100 ml (Jyoti et al., 2000).This indicates that values observed for rumen NH 3 -N in this study are adequate for microbial activities.
Apparent digestibility of diets by WAD goats fed V. amygdalina and T. diversifolia leaf meal based concentrates are shown in Table 4. Crude protein digestibility was higher (P<0.05) in T5 (89.49%) than T1 (84.23%).NDF digestibility was higher (P<0.05) in T5 (92.08) than other treatment diets, but similar in T2 (87.17),T3 (87.88) and T4 (88.99).All digestibility coefficients showed high digestibility levels which indicate that all diets were highly degraded in the rumen (Mapoon, 1980).Improvements in the digestibility values of DM and CP could be attributed to the positive influence of VATD leafmeal on the rumen environment in the goats.Forage mixtures used to replace brewers dried grains could have led to synchronized fermentability of individual chemical constituents leading to associative effects and improvements in DM intake and digestibility (Sinclair et al., 1995;Rosales and Gill, 1997).
Nitrogen utilization of WAD goats fed T. diversifolia and V. amygdalina leaf based concentrates is shown in Table 5. Nitrogen intake (g/day) of goats fed T4 (15.10) was higher (P<0.05)than those fed T1 (14.32) and T2 (14.16) while goats fed T3 (14.76) and T5 (14.88) had similar values.This observation seems not to be consistent with the protein levels of the diet fed, since there was a gradual decrease in level of protein as VATD leaf meal increased in the diet.However this trend observed for nitrogen intake is consistent with protein intake for goats.Earlier study (Okoruwa et al., 2013) reported that crude protein combination in a diet has significant effect on the nitrogen intake of sheep.N-balance and N-retention which are functions of nitrogen ingested and digested (Okoruwa et al., 2013) were positive in this study.Nitrogen balance values were similar in all diets.The positive nitrogen balance observed in all treatment groups suggest that the nitrogen absorbed, which is the difference between nitrogen intake and faecal nitrogen was well tolerated and utilized by the animals.Nitrogen retention (%) was lower (P<0.05) in goats fed T4 than in others, probably due to higher nitrogen intake and higher faecal N excretion.This observation corroborates the reports of Alli-Balogun et al. (2003) when they fed cassava foliage to sheep and observed high faecal and urinary nitrogen, which also led to poor nitrogen retention among the experimental animals.
Conclusion 1) T. diversifolia and V. amygdalina leafmeal is high enough in crude protein and comparable to those found in Wheat offal and PKC. 2) VATD leafmeal based diets can meet the maintenance nitrogen requirements of WAD goats, as all the experimental animals were observed to be in positive nitrogen balance.
3) WAD goats fed T. diversifolia and V. amygdalina leafmeal based concentrates as supplement to low protein P. maximum hay performed better on diets with concentrates containing leaf meals at levels not exceeding 10%.

Table 3 .
Performance characteristics, pH and rumen ammonia of WAD goats fed Tithonia diversifolia and Vernonia amygdalina leaf meal based concentrates.