Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition

Introduction

Semi-desert climate of Egypt is characterized by hot summer, dry and mild winters, low rainfall (5-200 mm/a) and high evaporation rates (1,500-2,400 mm/a). The country is characterized by particularly good wind systems with excellent locations along the shores of the Red and Mediterranean Sea [1]. South Sinai is an arid region that affects excessive salt natural resources (water, soil, plants, etc.). Feeding trees, shrubs and agricultural by-products are important in animal production because they do not compete with human food and can provide significant food supplements, especially in the dry season [2]. The use of forage trees and shrubs to solve problems associated with low productivity in small ruminant production has received research attention in recent years [3]. Smallholder ruminant farmers in developing countries cannot afford concentrates and rely almost entirely on feed browse fodders to replenish their stocks. Acacia (Acacia saligna) is a leguminous shrub which provides large amounts of fodder for ruminants in marginal regions [4, 5]. A. saligna has reasonably large amount of crude protein [6], high concentration of tannins [7, 8]. These compounds have adverse effect on the nutritional value to the browse species and also affect feed intake and digestibility [9]. Prosopis (Prosopis juliflora) is a leguminous shrub or tree that grows in semi-arid areas all over the world [10]. Also, prosopis has been reported to feed livestock by previous findings [11, 12, 13]. Moreover, [14] reported successful inclusion of prosopis at 30% level in the composite feed cattle without any negative influence on feed intake, digestibility and rumen fermentation. Leucaena (Leucaena leucocephala) a local available tree legume is used as hay, silage or fresh for ruminants due to its good characteristics such as elevated protein, palatability, vitamin and mineral especially sulfur content which positively affects microbial populations [15]. Moreover, leucaena has high digestibility of protein and dry mater [16]. However, [17] showed decreased dry matter intake, digestibility, protozoal populations and animal performance when feeding on leucaena, which contains some anti-nutrients factors such as phenolic compounds. Feeding a mixture of these tree legumes could be reduce and overcome the problems of palatability and toxic effects [18, 19, 3]. Accordingly, the objective of the study was to compare the nutritional performance of Barki sheep and doe Shami goats fed on a sun-dried chopped mixture of A. saligna, P. juliflora and L. leucocephala under arid and saline conditions of Southern Sinai in Egypt.

Materials and methods

The current study was carried out at Ras Suder Research Station which belongs to Desert Research Center, South Sinai Governorate, Egypt. This experiment aimed at investigate the effects of feeding mixture of acacia, prosopis and leucaena on feed intake, digestibility, nutritive value, body weight change, rumen and blood parameters of Barki sheep and doe Shami goats.

Preparation of fodder shrubs:

Three fodder trees legumes were collected with heights of approximately 1.0 -1.5 m. and diameters (0.5-2.5 cm.) from the Farm of Ras Suder Research Station and mechanically chopped into small pieces before introducing to animals.

Experimental animals and treatments:

Thirty-six pregnant Barki sheep and Shami goats were randomly divided into two equal groups, eighteen Barki sheep an averaged (26.56 ± 0.61kg) body weight and eighteen Shami goats an averaged (25.46 ± 1.40) body weight. Nine animals of each species were used as control group and fed alfalfa hay (Medicago sativa L.) with concentrate feed mixture. The other nine animals were fed ad libtum sun-dried chopped mixture contained 50% Acacia saligna, 25% Prosopis juliflora and 25% Leucaena leucocephala with concentrate diet. Diets were fed to cover total requirements of ewes and do as recommended by [20]. The chemical composition of mixture A. saligna, P. juliflora and L. leucocephala (Table 1) was determined according to [21].

Table 1: Chemical composition of experimental feed (as % on DM basis).

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 1

Management:

Animals were housed indoors inside semi-closed pens for 2-month then moved to metabolic cages. Daily feed offered and refusals were collected and weighed for each group of animals to estimate the actual feed intake and fresh water consumption was provided to animals twice daily over the trial period. However, the bi-weekly body weight changes were calculated by subtracting the live body weight at the start of the trial period from the live body weight and the finish of the trial period within each group.

Digestibility trails:

Four animals from each group were randomly chosen and used in digestibility trial to determine nutrients digestibility, nutritive value and nitrogen balance. Animals were placed in metabolic cages, weighted at the beginning and the end of the digestibility trial that lasted for 15 days of which the first 8 days were considered for adaptation period, followed by another seven days as collection period. During digestibility trial periods, feed amounts and residuals were daily weighed and recorded. Fecal output and urine were daily collected each from each animal and kept for later analysis. Ten percent of each fecal sample was taken and dried at 65°C for a constant weight and ground to pass through a 1.0 mm mesh screen for chemical composition. At the end of the trial, samples of rumen liquid were taken place after 3 hours feeding to estimate rumen ammonia and volatile fatty acids.

Chemical analysis:

Dry matter (DM) content of feeds and feces determined by drying at 105ºC for 24 hours, and organic matter (OM) by ashing at 550ºC in a muffle furnace for six hours. Ether extract (EE) and crude protein (CP) were determined according to [21]. Rumen volatile fatty acids (TVFA, s) were determined according to [22], while rumen ammonia nitrogen (NH3-N) was determined according to [21]. A total protein (TP) was determined according to Biuret method after [23]. On the other hand, albumin was determined according to [24]. Values of globulin were calculated by subtracting the value of albumin from the total protein whereas A/G ratio was calculated according to results of albumin and globulin. Total lipids concentration was determined according to [25]. Total cholesterol was carried out according to [26]. Glucose concentration was analyzed according to [27]. Concentrations of both alanine (ALT) and aspartate (AST) amino transferases were analyzed according to [28]. Alkaline phosphatase concentration (ALP) was determined according to [29]. Plasma urea and creatinine concentrations as indicators for kidney function were determined using bio diagnostic kits according to [30] and [31], respectively.

Statistical analysis:

All data were analyzed by the GLM procedure of SAS [32] with a model consisting of animal species × roughage group. Means were separated by least significant difference with a protected F-test (P<0.05). Means were presented in tables for animal species × roughage group regardless of the significance of the interaction effect. Where the following model was used:

Yijk = μ + Si + Tj + STij + eijk

Where,

Yijk = any observation of kth animal within jth roughage group within ith animal type,
μ = Mean
Si = Effect of animal type, i, 1-2 (1=sheep, 2=goats)
Tj= Effect of roughage group, j, 1-2 (1=alfalfa and 2= tree legumes mixture)
STij = the interaction between animal type and of roughage group.
eijk = Experimental error

Differences in mean values between treatments were compared by Duncan's multiple range test [33].

Results and discusion

Chemical composition:

Chemical compositions of the alfalfa hay, A. saligna, P. juliflora and L. leucocephala are presented in Table 1. The results showed that CP, EE and ash contents were higher in alfalfa hay than tree legumes mixture, while this mixture had higher CP, CF, NFE and OM% which could be safe cover the important nutrients requirements for animals [3]. Also [34] suggest that browse with potential as nitrogen supplements for ruminants fed low quality fodders through dry season in semi-arid regions. Moreover, shrubs and multipurpose trees has become a useful alternative ruminant feed in harsh semi-arid region [35, 36]. In addition, different studies suggested that the differences in their nutrient of forage legumes specially, CP and fiber content between these browse plants are probably due to sampling site, stage of plant growth and type (i.e., twigs, leaves or soft stem) of foliage sampled, season of collection, climatic influences soil type, fertility and water supply affect on nutrient concentrations in foliage growth [37, 38, 34].

Feed intake:

Mean values of body weight (BW), concentrate, roughage and total DM intake (g/Kg W 0.75/d) by compared sheep and goats are presented in Table 2. Average body weight (Kg W 0.75) was insignificantly higher in sheep than goats and between feeding treatments. At similar trend was observed with overall concentrate intake (g/Kg W 0.75/d) for both species and between feeding groups, while overall roughage and total DM intake (g/Kg W 0.75/d) were similar between both species. However, animals fed G2 showed lower (P<0.05) in roughage and total DM intake (g/Kg W 0.75/d) than those fed G1. This agrees with the reports of [7] who noted that DMI/kg W0.75 was similar between sheep and goats when fed on Acacia cyanophylla as based diets (84.9 vs. 84.4, respectively). In many ways, researcher related differences in DMI in species and report that sheep consumed more DMI vs. goats [39, 34]. Other studies reported that goats often eat more of some shrubs compere's sheep [40, 41, 42]. The lower values of dry roughage intake might be attributing to high content of anti-nutritional factors such as tannins [43]. Moreover, [44] reported that intake of mixed diets is an efficient way of diluting the adverse effects of secondary compounds in plants, such as tannins.

Table 2: Mean values of dry matter intake of ewes and does as affected by feeding tree legumes mixture during digestibility trial.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 2

Nutrient digestibility:

Results of dry matter (DM), organic matter (OM), crude protein (CP), crude fiber (CF), either extract (EE) digestibility or nutritive values where shown in Table 3. Goats had higher (P<0.05) digestibility coefficients of overall DM, CP and CF than sheep (71.93 vs. 67.83, 80.57 vs. 76.78 and 65.84 vs. 58.60 %, respectively) but there were insignificant differences among animal species in overall OM, EE and NFE digestibility. These results are in agreement with earlier reports by [34, 45] whose reported that DM and CF digestibility were higher for in goats than sheep probably reflecting their better capacity to detoxify secondary compounds in the rumen goats vs. sheep [46]. Moreover, higher digestibility of nutrients by goats may relate to many reasons like greater number of total protozoa in the rumen, total gut length in goats is lower and the retention time of digesta in goats is higher than sheep [47]. On the other hand, animals fed G1 showed higher (P<0.05) overall DM, OM and NFE digestibility than those fed G2 (73.21 vs. 66.55, 74.12 vs. 68.21 and 77.56 vs. 68.61 %, respectively) but overall CP, CF and EE digestibility were similar between both treatments. The lower values in digestibility of tree legumes mixture may be attributed to high content of tannins [48, 49]. Tannins could be reduced digestibility of crude protein and carbohydrate by inhibiting digestive enzymes and by altering permeability of the gut wall [50, 51]. Results of nutritive values Table (3) indicated that animals fed G1 had higher (P<0.05) TDN and DCP intake (g/kg W0.75) than those fed G2 but overall TDN and DCP intakes (g/kg W0.75) were similar between both species.

Table 3: Mean values of digestion coefficients by ewes and does as affected by feeding tree legumes mixture.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 3

Nitrogen utilization:

Nitrogen intake, excretion and balance (g/kg W0.75) are presented in Table 4. Overall nitrogen intake was similar between both species and was higher (P<0.05) for animals fed G1 vs. those fed G2 (2.66 vs. 1.57 g/kg W0.75 respectively). At similar trend, overall feacal, urinary and total nitrogen excretion (g/kg W0.75) were closed between both species and were higher (P<0.05) for animals fed G1 vs. those fed G2 (55 vs. 41, 1.03 vs. 34 and 1.58 vs. 0.75 g/kg W0.75 respectively) due to the greater supply of soluble nitrogen in the rumen. Also, nitrogen balance was similar between both species and was insignificant higher for those fed G1 vs. G2. Results are in agreement with those reported by [52] who indicated that goats would be able to utilize nitrogen more efficiently than sheep. The decline in nitrogen retention of animals fed tree legumes mixture vs. alfalfa hay might be due to the lack of soluble nitrogen or low digestibility in the basal diets and high tannins concentrations in browse species have been associated with reduced nitrogen retention [53, 54]. Conversely, diets high in condensed tannins can also increase post-ruminal absorption of nitrogen [55], decrease in fecal nitrogen excretion [56] and increase N retention [57].

Table 4: Nitrogen utilization by ewes and does as affected by feeding tree legumes mixture.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 4

Water utilization:

Water utilization by sheep and goats where summarized in Table 5. Data indicated that goats had slightly higher in overall drinking, metabolic and total water intake (ml/kg W0.82) compared to sheep (107 vs. 97, 28.24 vs. 27.08 and 193 vs. 185 ml/kg W0.82, respectively) while animals fed G1 had higher (P<0.05) in overall combined, metabolic and total water intake (ml/kg W0.82) than those fed G2 (107.5 vs. 11.68, 34.09 vs. 21.23 and 229 vs. 149 ml/kg W0.82, respectively). At similar trend, overall urinary, execration and water balance (ml/kg W0.82) were similar between goats and sheep and were higher (P<0.05) for those fed alfalfa hay vs. tree legumes mixture (60.11 vs. 33.15, 85.53 vs. 58.21 and 143 vs. 91 ml/kg W0.82, respectively). In corroboration with previous findings by [58] who reported that sheep and goats consumed comparable amounts of water intake but goats was excreted more feacal and urinary water than sheep. Unlike wise, there are other reports noted that sheep was higher in water intake vs. goats [59, 60, 61, 62].

Table 5: Water utilization by ewes and does fed diets containing tree legume mixture.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 5

Ruminal parameters:

Ammonia (NH3-N mg/100 ml) and volatile fatty acids (VFA´s m. equiv. /100 ml) concentrations are presented in Table 6. Goats had higher (P<0.05) overall ammonia NH3-N than sheep (35.43 vs. 27.90 mg/100 ml, respectively). In agreement with [64] who noted that, goats where considered to have a higher concentration of rumen ammonia, which could lead to improved fiber digestion. However, animals fed G1 showed higher (P<0.05) NH3-N than those fed G2 (35.26 vs. 28.07 mg/100 ml respectively). Lower concentrations of NH3-N in rumen fluid found with Acacia spp and Leucaena spp could be attributed to the inhibition of rumen protein degradation and deamination processes by condensed tannins [65, 66, 67]. Sheep had higher (P<0.05) overall ruminal TVFA´s than goats (11.18 vs.7.46 m. equiv. /100 ml respectively) and was lower (P<0.05) for animals fed G2 vs. G1 (7.27 vs. 11.37 m. equiv. /100 ml respectively). Incorporation with previous findings by [68] who noted that sheep had greater (P<0.05) in mean ruminal VFA concentrations compared with goats for all diets. The low concentrations of ruminal TVFA´s in rumen could be attributed to the reduce energy supply to the host [69].

Table 6: Rumen ammonia (NH3-N, mg/100 ml) and total volatile fatty acids (VFA´s, m. equiv. /100 ml) concentration of ewes and does as affected by feeding tree legumes mixture.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 6

Live body weight changes:

Body weight changes (kg) of ewes and does are presented in Table 7. The obtained results showed that values of body weight change (kg) and relative body weight (%) at end pregnancy period were insignificant between both species and feeding treatments. This agreement with finding of [70] they reported that, final body weight where similar in goats fed a diet having 50% of dietary Acacia karroo compared with other treatment groups. Moreover, [71] indicated that Awassi ewes fed Sesbania aculeate had a comparable live body weight of ewes for control group. In similar, [72] found that goats fed Leucaena leucocephala fodder for three months, maintained their body weights throughout the experimental period without anywhere deleterious effect. Similar results were reported by [73] were feeding pelleted diets containing different proportions of sun-dried L. leucocephala led to non-significant differences final body weight and average body weight changes of Jamunapari male goats.

Table 7: Body weight changes of pregnant ewes and does as affected by feeding tree legume mixture.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 7

Price cost of feed intake:

Cost of feed intake (h/d, L.E.) of ewes and does are reported in Table 8. Data showed that the lower at feed cost was noticed for animals fed G2 than those fed G1 in daily total feed cost, feed cost of kg total dry matter intake (TDMI) and TDN. Similarly, feed cost of Kg W 0.75 (L.E.) and relative cost of kg DMI (%) were lower price of mixture vs. control and were similar between both species. Our tree legumes mixture recorded reductions in feed cost of Kg W 0.75 about 53% for sheep and 54% for goats compared with control group due to the low price of tree legumes mixture compared with alfalfa. The results are in agreement with those reported by [74, 75, 76] they found that the feed cost was relatively lower than the control when sheep and goats fed rations contained 30-40% acacia.

Table 8: Price of feed intake by ewes and does during early pregnancy as affected by feeding salt tolerant plants.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 8

Blood parameters:

Data of blood parameters showed in Table 9. Sheep had slightly insignificant lower concentrations of overall total protein and globulin than goats (6.50 vs. 6.96 and 3.38 vs. 3.97 (g/dl), respectively) while it showed insignificant higher of overall albumin and albumin/ globulin ration (A/g ratio) than goats (3.12 vs. 2.99 and 0.94 vs. 0.75, respectively) with no significant different among treatments. These findings were in harmony with those reported by [77, 78, 79, 80]. Also sheep had slightly insignificant higher concentrations of overall urea and creatinine than goats (41.24 vs. 39.87 and 1.25 vs. 1.19 (mg/dl), respectively) with insignificant effect between experimental diets. In similar, [80] found that animals fed mixture of sun-dried acacia, prosopis and leucaena showed lower mean concentration of urea and creatinine compared with control group. It might be due to the high presence of condensed tannins, which led to reduce the ruminal proteins degradation in turn and caused a reduction of urea nitrogen levels in sheep and goats [81]. At the same trend, goats recorded insignificant higher values of overall AST and ALT compared to sheep (24.06 vs. 19.32 and 29.31 vs. 23.49 (IU/l), respectively). The results were in agreement with [80]. In general, the increase of ALT or AST activity might be caused by high tannins [82]. Also goats had higher overall total lipids and glucose than sheep (2.94 vs. 2.75 (g/l) and 44.45 vs. 39.65 (mg/l), respectively) but sheep showed higher overall cholesterol than goats (1.25 vs. 1.19 (mg/dl), respectively) with no differences were observed between treatments. In agreement with [80] who demonstrated that feeding tree legumes mixture decreased mean values of plasma total lipids, cholesterol and glucose compared with alfalfa hay. The reduction in total lipids might be attributed that such tree legumes mixture and low fat contents in such desert plants. Moreover, this decrease in blood cholesterol and glucose levels might be attributed to the anti-nutritional factors in these plants [83, 84].

Table 9: Mean values of some blood metabolites concentration of ewes and does as affected by feeding tree legumes mixture.

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition - Image 9

Conclusion:

In brief, we can say that using sun-dried chopped mixture contained 50% Acacia saligna, 25% Prosopis juliflora and 25% Leucaena leucocephala as non-traditional could to uses a solve of some problems and providing as good alternative feed resources mainly in summer and autumn seasons when the other conventional forage resources are shortage without having any adverse effect on nutrient intake and performance of Barki sheep and doe Shami goats under desert conditions of South Sinai, Egypt.

Acknowledgment

This experiment is a part of the regional project titled “Adaptation to climate changes in WANA marginal environments through sustainable crop and livestock diversification” which is funded by International Center for Biosaline Agricultural (ICBA), UAE.

This article was originally published in American-Eurasian Journal Of Sustainable Agriculture. 12(1) 2018, Pages: 10-21. This is an Open Access article licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/.