Comparative nutritional studies of ewes and does fed salt tolerant plants under desert condition

Published on: 3/25/2019
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Summary

The study was carried out at South Sinai Research Station, South Sinai Governorate, Egypt. Twenty eight pregnant Barki sheep and Shami goats were used to evaluate the effects of feeding cultivated salt-tolerant forages mixture, old man saltbush (Atriplex nummularia L.), Sorghum (Sorghum bicolor L.) and pear millet (Pennisetum glaucum L.) on feed intake, nutritive value, digestibility, nitrogen utilization, body weight changes, rumen and blood parameters. Animals were randomly assigned into two equal groups (14 animals each specie). Seven animals of each species were used as control and fed fresh alfalfa (Medicago sativa L.) with concentrate diet (mixture group). The other seven animals were fed mixture contained 50% A. nummularia, 25% S. bicolor and 25% P. glaucumad libitum with concentrate diet (mixture group). Data showed that values of dry roughage and total DMI (g/KgW0.75/d) were insignificant between both species and was higher for control group vs. mixture group. However, digestibility coefficients of CP and CF were higher for goats than sheep but were insignificantly differences in DM, OM and EE digestibility between both species. Also goats had higher in DCP% vs. sheep but were no significant differences in TDN, DCP intake (g/h/d) and TDN% among ewes and does. Nitrogen intake, excretion and balance (g/KgW0.75) were higher for control group vs. mixture group but was insignificantly differences between both species. Animals fed mixture group consumed water more than those fed a control group while urine, faces and total water execration were higher for same animals vs. control group. Sheep had higher ruminal TVFA's (m. equiv. /100 ml) than goats and was greater for control vs. mixture group but values of rumen ammonia (NH3-N mg/100 ml) were insignificantly between two species and treatments. However, significantly differences of NH3-N were detected in interaction between species and treatments. Animals fed Salt-tolerant plants mixture had higher values of body weight change (kg) and relative body weight (%) of mid pregnancy than those fed alfalfa. Values of glucose, total lipids and creatinine were significant in interaction between species and treatments. On the other hand, insignificant differences were observed in other blood parameters between species, treatments and interaction between species and treatments. Under arid and saline conditions in Sinai we could be recommended a mixture contained some cultivated salt-tolerant forages as a non-traditional feed resources which can improve small ruminants performance. [Helal H. G., Eid E. Y, Nassar M. S, Badawy H. S. and El Shaer H. M. Comparative nutritional studies of ewes and does fed salt tolerant plants under desert condition. Nat Sci 2018;16(6):62-72]. ISSN 1545-0740 (print); ISSN 2375-7167 (online). http://www.sciencepub.net/nature. 10. doi:10.7537/marsnsj160618.10.

Keywords: Sheep, Goats, salt-tolerant plants, intake, digestibility, nitrogen utilization, rumen and blood parameters.

1. Introduction 

In Egypt, small ruminants are essential resources of cash revenue, savings nutrition (meat and milk), wool, compost and employment of many people particularly in populations with a low income and where poverty prevails. Improving the sustainability of animal production systems in Sinai by increasing the availableness of fodder resources through inducting of salt-tolerant fodder crops is considered one of the means to insure sustainable development of Bedouin communities in Sinai. Saline soils of various degrees occupy over 80 million ha. in the Mediterranean basin (Anon., 2006). Some studies recommended cultivating of salt-tolerant fodder shrubs (e.g. A. nummularia spp.) and salt tolerant grasses such as sorghum (S. bicolor L.) and pearl millet (P. glaucum L.) which might fill the gap in feed production in saline and dry areas (Hanafy et al., 2007 and El Shaer, 2010). Old man saltbush (A. nummularia L.) is a forage shrub originating in several marginal areas around the world as a vital source in the formulation of ruminant diets. This species recognized to be tolerant to salinity and drought as well as to high content of crude protein, fiber and minerals (El Shaer, 2010 and Ben Salem et al., 2010). High minerals concentrations can decrease food consumption, produce mineral imbalances and higher drinking water requirements (Norman et al., 2008 and Masters et al., 2005b). P. glaucum and S. bicolor are among the most likely salt-tolerant grass species as good quality fodders for small ruminants in Egypt and other countries in the Near East (Anon., 2009). Moreover, S. bicolor straw could be included part of roughage component in the small ruminant rations at different levels without any affecting of feed intake, digestibility and nitrogen balance (Venkateswarlu et al., 2014). Some anti-nutritional factors similar lignin oxalates and nitrates of salt-tolerant forages and halophytes could restrict in animals feeding mainly when they are used as sole diets. The presence of these compounds forms insoluble complexes with necessary minerals, proteins and carbohydrates, lowering the nutritive value of the product (El Shaer, 2010). Therefore, appropriate mixing of grass with shrubs has been assumed as an effective method of diluting the adverse effects of unlike secondary compounds especially, tannins (Bhat et al. 2013). Therefore, the target of this study was conducted to evaluate the effect of feeding cultivated salt-tolerant plants mixture of (A. nummularia, S. bicolor and P. glaucum) on nutritional performance of female Barki sheep and doe Shami goats under Southern Sinai conditions.

 

2. Material and Methods

The current experiment was carried out at South Sinai research Station (Ras Sudr) which belongs to Desert Research Center, Ministry of Agriculture and Land Reclamation, South Sinai Governorate, Egypt. Three cultivated salt-tolerant plants mixture were collected from the Farm of South Sinai Research Station. This study was conducted so as to monitor nutritional parameters changes of ewe Barki sheep and doe Shami goats as a result of feeding a sun-dried chopped mixture at rate of 50, 25 and 25%, respectively.

Animals and Treatments

Twenty-eight pregnant Barki sheep and Shami goats were randomly assigned into two equal groups, fourteen Barki sheep an averaged (29.50±1.28 kg) body weight and fourteen Shami goats an averaged (25.62±1.33 kg) body weight. Seven animals of each species were used as control and fed fresh alfalfa (Medicago sativa L.) with concentrate feed mixture (control group). The other seven animals were fed mixture contained 50% A. nummularia, 25% S. bicolor and 25% P. glaucumad libitum with 40% of concentrate feed mixture (mixture group). Alfalfa and concentrate feed mixture were given to cover energy maintenance and production requirements of ewes and does according to the nutritional requirements of Kearl (1982). The chemical composition of mixture of A. nummularia, S. bicolor and P. glaucum and fresh alfalfa (Table 1) was determined according to A.O.A.C. (2000).

 

 

Experimental procedures

Animals stayed in a semi-closed pen, roofed with and walled in four directions with concrete for 2- month period then moved to metabolic cages. Feed offered and refusals were daily collected and weighed for each group of animals to estimate the actual feed intake. The rations were adjusted every two weeks according to the changes of live body weight. Fresh water was available twice daily, at 08:00 and 14:00 h.

Weight changes

All animals were weighed biweekly up to end of the experiment and those were weighed in the morning before feeding. Body weight changes were calculated by subtracting the live body weight at the beginning of the experimental period from the live body weight at the end of the experimental period within each group.

Digestibility trails

Four animals from each group were randomly chosen and used in digestibility trial to determine digestibility, feeding value and N balance. Animals were housing in metabolic cages, weighted at the start and the end of the digestibility trial that lasted for 14 days (7 days as an adaptation period followed by 7 days as a 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 65ºc 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 3 hrs after feeding to estimate rumen ammonia and volatile fatty acids concentrations.

Analytical procedures

Dry matter (DM) content of feeds and feces determined by drying at 105ºC for 24 hours and organic matter (OM) by ashing at 550°C in a muffle furnace for 6 hours. Ether extract (EE) and crude protein (CP) were determined according to AOAC (2000). Ruminal fluid samples were analyzed for VFA (Warner 1964) and ammonia-N (AOAC 2000). Blood samples were analyzed for total proteins and albumin (Gornal et al. 1949 and Doumas et al. 1971 respectively), globulin was calculated by subtracting the value of albumin from the total protein whereas A/G ratio was calculated according to results of albumin and globulin, plasma total lipids, total cholesterol and glucose concentrations (Schmillet 1964, Roeschlau et al. 1974 and Tietz 1986 respectively), alanine (ALT) and aspartate (AST) amino transferases (Reitman and Frankel 1957), alkaline phosphatase (ALP) (Belfield and Goldberg 1971), plasma urea and creatinine concentrations as indicators for kidney function (Fawcett and Soctt 1960 and Schirmeister et al. 1964 respectively).

Statistical Analyses

Data were analyzed by using GLM procedure of the SAS statistical package (SAS, 2004) with a model consisting of species, Treatments and species x Treatment. Means were presented in tables for animal species x Treatments regardless of the significance of the interaction effect. The least significant difference was used for comparing means. Differences between means with P<0.05 were accepted as statistically significant differences and those with 0.05<P<0.10 were accepted as expressive tendencies to differences. Differences in mean values between treatments were compared by Duncan's multiple range test Duncan (1955).

 

4. Results and Discussion

Chemical composition

The nutritional compositions of  A. nummulariaS. bicolor, P. glaucum and alfalfa are offered in Table 1. The concentrations of CP and ash content were generally higher values (12.35 and 21.73%, respectively) in A. nummularia than salt grass of P. glaucum and S. bicolor but the concentrations of CP and EE in alfalfa was higher than all salt-tolerant plants. The results are agreement with many investigators tested the saltbush as animal feed materials (Shawket et al, 2001; El -Shaer, 2006 and Fayed et al, 2010). S. bicolor recorded the highest values of OM, CF and NFE (86.29, 22.99 and53.53%, respectively) compared to other forage in this study. The high crude fiber of S. bicolor may be attributed to the high cell-wall constituents (Abdu, 1998). Salt- tolerant plants mixture in this study was higher in CP (9.37%) than the maintenance requirements for ruminants as recommended by (Norton, 2003) who determined that feeds contain less than 8% CP could not provide the ammonia levels required by rumen microbes for optimum activity.

Feed intake

Data of feed intake, digestibility and nutritive value by ewes and does are shown in Table 2. Values of dry roughage and total DMI (g/Kg W0.75/d) were insignificant between both species and was higher (P<0.01) for control group vs. mixture group (73.83 vs. 35.16 and108.86 vs. 70.60 g/Kg W0.75, respectively). Similar trend was observed with interaction among two species and treatments. In many ways, Authors related differences in DMI to breed and reporting that goats consumed more DMI vs. sheep (Gihad et al., 1980; Nefzaoui et al., 1993; Bartolome et al., 1998 and Rogosic et al., 2006). On the contrary, other reports observed that sheep had higher DMI than goats (Quick and Dehority, 1986; Aregheore, 1996; El Hag and A1 Shad 1998; Santra et al., 1998 and Salem et al. 2006), while others found that DMI of A. nummularia was higher for sheep vs. goats (Souza et al., 2004 and Alves et al., 2007). Moreover, similar DMI for both species were found by (Hadjipanayiotou, 1995 and Moujahed et al., 2005). In conclusion, Ngwa et al., 2000 and Lu et al., 2005 were discussed that The difference in DMI between two species may be due to the differences in anatomy and physiology characteristics of the digestive tract, and Abu-Zanat and Tabbaa 2006 reported that lower DMI of mixture group may be attributed to high salt content and anti-nutritional factors such as tannins in A. nummularia which contained 6.6% oxalates and 5.2% hydrolysable tannins as DM.

Digestibility coefficients

Crude protein (CP) and crude fiber (CF) digestibility were higher (P<0.01) for goats than sheep (80.59 vs. 73.32% and 53.10 vs. 45.52%, respectively) but was insignificantly differences in DM, OM and EE digestibility between both species. However, animals fed control group had higher (P<0.01) digestibility coefficients of DM, OM, CP, CF and NFE  vs. those fed mixture group. A significant interaction was detected among two species and treatments (Table 2). These results are similar to other reports showed higher CF digestibility for goats than sheep (Alam et al, 1985; Leng, 1991; El Hag and A1 Shad 1998; Salem et al., 2006 and Agrawal1 et al., 2014). This may be related to larger populations of cellulolytic bacteria for goats vs. sheep (Gihad et al., 1980). Lower digestibility of salt-tolerant plants mixture vs. alfalfa may be due to added A. nummularia and the effect of salt content in the ruminal environment by rumen osmolality changes (Meneses et al., 2012 and Moreno et al., 2017). Thus leading to increase water intake, consequential influences on rumen physiology and metabolism of animals (Konig, 1993).

Nutritive values

Data of nutritive values by ewes and does indicated that control group recorded higher (P<0.01) TDN, DCP intake (g/h/d), TDN and DCP% vs. those fed mixture group. Also, goats was higher (P<0.01) in DCP% vs. sheep but was no significant differences in TDN, DCP intake (g/h/d) and TDN%. Significant increment of TDN in control group might be attributed to higher digestibility of OM, CP, CF and NFE than those of mixture group (Table 2). This concurs with earlier reports by (Al-Owaimer et al., 2008 and Fayed et al., 2010) they noticed that lambs fed alfalfa had higher TDN than those fed Atriplex species. Furthermore, TDN value for ration containing Atriplex was lower by 7.15% than that containing berseem hay (Ahmed et al., 2001). In the current study,  the elevation of DCP intake and DCP% in alfalfa may be due to higher CP content and rapid fermentation than that Salt-tolerant plants mixture (Table 1). Similar observations were reported by (Fayed et al., 2010).

 

 

Nitrogen utilization

Nitrogen intake, excretion, and balance are presented in Table 3. Data indicated that nitrogen intake, total N excretion and N balance (g/KgW0.75) were higher (P<0.01) for control group vs. mixture group (2.66 vs. 1.36, 1.03 vs. 0.44 and 1.08 vs. 0.56 g/KgW0.75, respectively). At similar trend was observed with interaction among two species and treatments. These differences may be due to high content of CP and digestibility in control group vs. mixture group. These results are similar to other reports that showed an increase total N excretion for animals fed alfalfa compared with those fed old man saltbush (Shawket et al., 2005; Fayed et al., 2010 and Abdou et al., 2011). However, it was insignificantly differences between both species in nitrogen intake, excretion and balance except feacal nitrogen excretion (g/KgW0.75) was higher (P<0.01) for sheep vs. goats (0.53 vs. 0.38, respectively).

Water utilization

Water utilization by ewes and does are illustrated in Table 4. Data was related to the metabolic body mass (W0.82) indicate that animals fed mixture group consumed water more (P<0.01) than those fed a control group (214 vs. 88.65 ml/Kg W0.82, respectively) while urine, feacal and total water execration were higher (P<0.01) for same animals vs. control group (99.65 vs. 60.11, 41.19 vs. 25.42 and 140.84 vs. 85.53 g/Kg W0.82, respectively). This concurs with earlier reports showed higher water intake and excretion for animals fed Atriplex spp vs. control group (Shawket et al., 2005; Allam et al. 2006; Hassan, 2009; Bhatti et al., 2009 and Ben Salem et al., 2010). On the other hand, water consumption and excretion were similar between both species. Similar results were reported by Gihad et al. (1989) who found that sheep and goats consumed relatively similar amounts of water intake but goats were excreted more feacal and urinary water than sheep. However, previous findings showed higher water intake for sheep vs. goats (Alam et al, 1985; Kandil and El  Shaer, 1988; Gihad et al., 1989; Ferreira et al. 2002; Hadjigeorgiou et al. 2003 and Van, 2006).

Water balance was insignificantly higher for sheep vs. goats (141.46 vs. 128.22 ml/kg W0.82, respectively) and was lower for animals fed mixture group vs. control group (Table 4).

 

 

 

Ruminal parameters

Rumen ammonia (NH3-N mg/100 ml) and volatile fatty acids (VFA´s m. equiv. /100 ml) concentrations are presented in Table 5. Data showed insignificant values either for species or treatments while goats had high value of ammonia NH3-N vs. sheep (39.56 vs. 31.44 mg/100 ml respectively). However, values were significantly differences in interaction between two species and treatments. Similarly, the current ruminal NH3-N concentration was reported to be higher than the level required for maximum rumen microbial growth (Mehrez et al. 2001). The results obtained in this study agree with the findings by Domingue et al. (1991) and Carro et al. (2012) who reported that goats had higher value of ruminal NH3-N concentration vs. sheep. This may be attributed to goats had larger populations of cellulolytic bacteria than sheep as a result to greater rumen protein degradation and longer retention time of digest a in the rumen which could lead to a better fiber digestion and being better utilizers of poor roughages (Gihad et al., 1980 and Domingue et al., 1991). Moreover, Alam et al. (1985) concluded that ability of goats to maintain higher rumen NH3-N concentration with low N diets was associated with their lower water intake. Reduced rumen NH3-N concentrations of mixture group vs. control group could be attributed to decreased N intake and protein degradation (Ramos et al., 2009). Sheep had higher (P<0.01) ruminal TVFA's than goats (11.51 vs. 7.32 m. equiv. /100 ml, respectively) and was greater for control vs. mixture group. A significant interaction was observed between species and treatments (Table 5). This improved yield of rumen TVFA's concentrations may be due to the increases of OM digestibility in control vs. mixture group. The results were in agreement with Carro et al. (2012) who observed that sheep were greater ruminal VFA concentrations compared with those found in goats for all diets. Lower values of rumen TVFA's concentrations of mixture group vs. control group may be due to anti-nutritional factors such as tannins in A. nummularia which caused to inhibit cellulolytic and protolytic enzymes and decrease the production of volatile fatty acids (Abu-Zanat et al., 2003b and Abu- Zanat and Tabbaa, 2006). Likewise, higher salt and lower energy contents of saltbush which decrease the production of TVFA's in the rumen (Shawket and Ahmed, 2009 and Aschenbach et al., 2011).

 

 

Live body weight changes

Body weight changes (BWC) by ewes and does are shown in Table 6. The results revealed that sheep had higher (P<0.05) values of body weight of mid pregnancy, end of pregnancy, Total BWC and highly significant (P<0.01) in BWC of mid pregnancy than goats (32.81 vs. 27.50, 36.56 vs. 31.43, 7.06 vs. 5.81 and 2.68 vs. 1.88kg, respectively). The same trend was observed with interaction among two species and treatments. The higher BW in sheep vs. goats could be due to changes in aggressive behaviors, genetic capacity or production systems (Van, 2006). Also, Konig (1993) showed that differences in BW of small ruminants fed diets containing levels of Atriplex spp were mostly due to an increase in total body water (average 22.3 g per day). However, animals fed Salt- tolerant plants mixture (mixture group) had higher (P<0.05) values of BWC of mid pregnancy (kg) and relative body weight of mid pregnancy (%) than those fed alfalfa (control group). Similarly, studying on  Barki lambs, Shaker et al. (2014) reported that feeding mixture of A. nummularia, S. bicolor and P. glaucum was non-significant differences in BWC with control group. Furthermore, Abu-Zanat and Tabbaa (2006) reported that Awassi ewes receiving diets containing 50 and 100% saltbush had not significantly different of overall BW changes compared with control group. On the other hand, many authors found that BW gain was reduced in small ruminants fed Atripex spp.  (Shehata et al. 1988 and Badawy et al. 2002).

Price cost of feed intake

Cost of daily feed (L.E.) of ewes and dose illustrated in Table 7. Data revealed that the lower feed cost along the feeding period was observed for animals fed mixture group vs. those fed control group in total feed cost, feed cost of kg total dry matter intake, TDN and DCP. At the same trend, feed cost of Kg W 0.75 (L.E.), relative cost of kg TDN and DCP% were low price of mixture group vs. control group and was similar between both species. Salt-tolerant plants mixture recorded a reductions in feed cost of Kg W 0.75 about 52% for sheep and 55% for goats compared with control group due to the low price of salt-tolerant plants mixture compared with alfalfa. The results are  in agreement with those reported by Mousa and El- Shabrawy (2003) and Mehrez et al. (2011) they found that the feed cost was relatively lower than the control when sheep and goats fed rations contained 30-40% acacia.

Blood parameters

Blood parameters of sheep and goats are showed in Table 8. Data indicated that concentrations of glucose and total lipids were significant (P<0.05) for control vs. mixture group. However, animals fed mixture group had higher (P<0.01) ALP than control group while concentrations of creatinine was increased (P<0.01) for control group vs. mixture group. Also, values of glucose, total lipids and creatinine were significant (P<0.05) in interaction among two species and treatments. On the other hand, insignificant differences were observed in other blood parameters between species, treatments and interaction between species and treatments. In similar studies, Shaker (2014) who found that glucose and total lipids concentrations were significantly lowered in animals fed mixture group than the control group. Lower  values of blood parameters among animals fed control group and those animals fed mixture group which might be attributed to high salt content (Salem et al. 2004, El- Shaer et al., 2005 and Fayed et al., 2010) and anti-nutritional factors such as tannins (Patra et al., 2002, Cook et al. 2008 and Ben Salem et al., 2010).

 

 

 

 

Conclusion

It could be concluded that introducing salt tolerant plants A. nummularia, S. bicolor and P. glaucum for Barki sheep and doe Shami goats could be an attempt to reduce feed shortage and high prices for livestock in arid and saline conditions prevailed in Southern Sinai, Egypt and to increase the utilization of the available unpalatable salt tolerant plants without any adverse effect on performance of animals.

 

Acknowledgment

This experiment was supported by International Center for Biosaline Agricultural (ICBA), UAE as regional project titled “Adaptation to climate changes in WANA marginal environments through sustainable crop and livestock diversification.

 

This article was originally published in Nature and Science 2018;16(6):62-72]. ISSN 1545-0740 (print); ISSN 2375-7167 (online). http://www.sciencepub.net/nature. 10. doi:10.7537/marsnsj160618.10. 

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