Introduction
South Sinai is semi-arid area with salt affected natural resources (plants, water, soil, etc). Therefore, feed resources in this region characterize one of the main difficulties for animal production development. Farmers in Egypt are concerned with ways to prevent salinification and economically produce fodder crops to overcome the problems of feed shortage that lead to high feeding costs (Fahmy et al., 2010). On the other side, big differences were found between salt tolerant plants and halophytes, the last one containing high level of salt, mainly including Na, K, and Cl (El Shaer, 1981 and Abd El-Rahman, 2008). The high dietary salt heaps for sheep possibly bring a series of bad effect, including decreasing the energy use efficiency for production (Arieli et al., 1989), voluntary feed intake (Blache et al., 2007) and productivity (Warner and Casson, 1992). Also, some halophytes are scarce in sulphur and phosphorus (El Shaer, 1981).
Many studies have been conducted on utilization of some saltbush plants species such as old man (Atriplex nummularia), Pear millet (Pennisetum americanum) and Sorghum grass (Sorghum bicolor) as individual fodder crops. Few researches were carried out on utilization of a combination or salt tolerant fodders mixture as small ruminants feed materials (Gutteridge and Shelton, 1994; Arunachal et al., 2002; Ben Salem et al., 2002 and El-Shaer, 2006).
Small ruminants in the semi-arid areas need to approve special physiological functions to maintain thermal equilibrium against fluctuations in environmental temperature. Moreover, animals undergoing salt stress need to adjust many physiological systems to keep mineral and fluid balance. Accordingly, physiological responses must be investigated at introducing salt plants to animal feeding under semi-arid conditions.
This study was therefore planned to determine the potential of feeding salt-tolerant fodder crops mixture (Atriplex nummularia, Sorghum bicolor and Pennisetum americanum at percentage of 50, 25 and 25%, respectively) compared with the conventional Berseem hay (Alfalfa) to evaluate their effect on nutritional and physiological performance of Shami goats.
Materials and methods
This study was carried out at South Sinai Station (Ras Sudr) which belongs to Desert Research Center, Ministry of Agriculture and Land Reclamation, Governorate of South Sinai, Egypt. This study was conducted to investigate the influences of feeding salt-tolerant plants mixture on live body weight changes, feed intake, digestibility, thermo-respiratory responses and blood picture of female Shami goats.
Experimental animals and design:
Eighteen Shami female goats, aged 3 - 3.5 years old with an average body weight 25.00±2.26 kg, were divided into two equal groups. The first group (G1) was fed alfalfa (Medicago sativa L., 4th cut) and served as control, while the second group (G2) was fed a mixture of Atriplex nummularia, Sorghum bicolor and Pennisetum americanum at rate of 50, 25 and 25 %, respectively. Both groups were provided by concentrate feed mixture (CFM). All animals of this experimental were fed their nutrient requirements according to Kearl (1982) and were offered at the ratio of 1:1 roughage to concentrate, and the real intake was estimated after weighing the refusals. The chemical compositions of the mixture of salt tolerant plants, alfalfa and feed concentrate mixture were established according to A.O.A.C. (2000) and presented in Table (1).
Table 1: Chemical composition (%) of experimental feed stuffs (on DM basis)
Management:
Fresh water was available twice daily all over the experimental period. The animals in this experiment were housed in a semi-closed pen, roofed and walled in four directions with concrete.
Weighing animals and body weight changes:
All animals were weighed at the starting of the experiment and then at biweekly intervals up to finish of the experiment. The animals were weighed in the morning before supplementary feeding and after fasting period about 12 hours. Changes of body weight were calculated.
Digestibility trial:
In the middle of the experiment period, four animals per each treatment 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 start and the end of the trial. The trial of digestibility continued for 21 days from which the first 14 days were considered as an adaptation and preliminary period, followed by 7 days as collection period. Over the collection period, daily amount of feed consumed and residuals were accurately weighed and recorded, feaces and urine were quantitative collected from each animal. Ten percent of each fecal sample was taken and dried at 65 ºC 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.
Climatic elements and physiological responses:
Simultaneously diurnal variation of air temperature ºC (AT) and relative humidity (RT %) at the level of these animals in present study were recorded using centigrade thermometer and hygrometer in a weather station (Stevense’s screen). Rectal temperature (RT) was measured to the nearest 0.1 0 C using a standard clinical thermometer inserted into the rectum approximately 10 cm for 2 minutes. Skin and coat temperature (ST & CT) were measured on the mid-side position, using a telethermometer for one minute. Respiration rate (RR) was recorded by counting frequency of flank movements per minute. (RT, RR, ST, CT). All these parameters were determined biweekly through the experiment. All parameters were recorded twice daily at 8:00h and 14:00h.
Sampling method:
Blood samples from all goats of each group were collected through vein puncture (using clinical needle). Blood samples were centrifuged at 3000 rpm for 15 min for the separation of serum and kept frozen at -20 ºC until further analysis. Blood picture parameters; RBCs and WBCs were counted in blood under the microscope by means of haemocytometer, according to Kolmer et al., (1951). Packed cell volume (PCV) was estimated using microhematocrit tubes by Wintrob methods, while hemoglobin concentration (Hb %) was estimated by the method of Crosbyet et al., (1954). Mean corpuscular volume (MCV); (MCH) and (MCHC) were calculated by the following equations:
MCV femto liter (fl) = (PCV x 10) / RBCs in million
MCH pictogram (pg) = (Hb x 10)/RBCs
MCHC % = (Hb x 10)/PCV
Feedstuffs chemical analysis:
Dry matter (DM) content was determined by drying at 105 ºC for 24 hours, and organic matter (OM) by ashing at 550 ºC for 6 hours. Ether extract (EE) and crude protein (CP) were determined according to AOAC (2000). Rumen volatile fatty acids were measured according to Warner (1964), while rumen ammonia nitrogen was determined according to AOAC (2000).
Statistical analysis:
Experimental data were analyzed using General Linear Model Procedure (SAS, 2004) and differences between means were tested using methods of Duncan (1955).
Results and discussions
Dry matter intake and digestion coefficients during digestibility trial:
During the digestibility trial, feed intake and nutrients digestibility are illustrated in Table (2). The results shown that concentrate intake (g/d or g/kg0.75/day) was not influenced by feeding mixture of salt tolerant fodder crops. However, roughage intake (g/d or g/kg0.75/day) was affected significantly by treatment. Animals fed on alfalfa (G1) had higher (P<0.05) value of roughage intake than animals fed on salt tolerant fodder crops mixture (G2). Mean values were 931 and 349 g/d, respectively. Similar results were recorded by Ben Salem et al., (2005 and Hassan (2009). ><0.05) value of roughage intake than animals fed on salt tolerant fodder crops mixture (G2). Mean values were 931 and 349 g/d, respectively. Similar results were recorded by Ben Salem et al., (2005 and Hassan (2009).
Data in Table (2) showed that, the treatment had a significant effect on all digestion coefficients, except for crude protein digestibility. Animals fed on alfalfa had higher (P<0.05) values of DM, OM, CF, EE and NFE digestibility than that fed on salt tolerant fodder crops mixture. These results are in compact with those reported by Fayed et al., (2010) who found that the apparent digestibility of OM, CP and NFE were high in sheep fed alfalfa than other groups. These results might be due to higher salt content of atriplex (Wilson, 1992). The increase of CP digestibility by animals of G2 might be due to increase the protein content of Atriplex nummularia in salt tolerant fodder crops mixture. The same trend was observed with the nutritive values, TDN and DCP percentage. Animals in G1 group had higher (P><0.05) values of TDN and DCP % than those in G2 group. Mean values were 67.36 and 54.88% for TDN and were 12.35 and 9.98% for DCP, respectively. The improvement in TDN and DCP% of animals in G1 was mainly due to the better digestibility and feed utilization. The elevation of TDN and DCP% in alfalfa may be due to the highest digestibility of OM, CP, CF and NFE than salt plants.><0.05) values of DM, OM, CF, EE and NFE digestibility than that fed on salt tolerant fodder crops mixture. These results are in compact with those reported by Fayed et al., (2010) who found that the apparent digestibility of OM, CP and NFE were high in sheep fed alfalfa than other groups. These results might be due to higher salt content of atriplex (Wilson, 1992). The increase of CP digestibility by animals of G2 might be due to increase the protein content of Atriplex nummularia in salt tolerant fodder crops mixture. The same trend was observed with the nutritive values, TDN and DCP percentage. Animals in G1 group had higher (P<0.05) values of TDN and DCP % than those in G2 group. Mean values were 67.36 and 54.88% for TDN and were 12.35 and 9.98% for DCP, respectively. The improvement in TDN and DCP% of animals in G1 was mainly due to the better digestibility and feed utilization. The elevation of TDN and DCP% in alfalfa may be due to the highest digestibility of OM, CP, CF and NFE than salt plants.><0.05) values of TDN and DCP % than those in G2 group. Mean values were 67.36 and 54.88% for TDN and were 12.35 and 9.98% for DCP, respectively. The improvement in TDN and DCP% of animals in G1 was mainly due to the better digestibility and feed utilization. The elevation of TDN and DCP% in alfalfa may be due to the highest digestibility of OM, CP, CF and NFE than salt plants.
Table 2: Intake and digestibility of concentrate feed mixture, Berseem (alfalfa) and salt tolerant plants by female Shami goats
Nitrogen balance:
Nitrogen intake, excretion, and balance are presented in Table (3). Nitrogen intake (g/d) was higher (P<0.05) for Shami goats in G1 group as compared to that in G2 group. Fecal and urinary nitrogen were greater (P><0.05) for G1 group as compared to G2 group, and then total nitrogen excretion was higher (P><0.05) for G1 group than G2 group. On the other hand, nitrogen balance as g/d or percentage from nitrogen intake was not significantly different between two groups, but animals in G1 group had high value of NB than that in G2 group when express it as a g/d. Mean values were 13.65 and 8.84 g/d, respectively. This may be due to higher CP content and its higher digestibility in alfalfa than that in G2 group. However, animals in G2 group had high value of NB than that in G1 group when expressing it as a percentage from nitrogen intake. Mean values were 55.47 and 41.20 %, respectively. These results are in agreement with those of Shawket et al., (2005) and Fayed et al., (2010).><0.05) for G1 group as compared to G2 group, and then total nitrogen excretion was higher (P<0.05) for G1 group than G2 group. On the other hand, nitrogen balance as g/d or percentage from nitrogen intake was not significantly different between two groups, but animals in G1 group had high value of NB than that in G2 group when express it as a g/d. Mean values were 13.65 and 8.84 g/d, respectively. This may be due to higher CP content and its higher digestibility in alfalfa than that in G2 group. However, animals in G2 group had high value of NB than that in G1 group when expressing it as a percentage from nitrogen intake. Mean values were 55.47 and 41.20 %, respectively. These results are in agreement with those of Shawket et al., (2005) and Fayed et al., (2010). ><0.05) for G1 group than G2 group. On the other hand, nitrogen balance as g/d or percentage from nitrogen intake was not significantly different between two groups, but animals in G1 group had high value of NB than that in G2 group when express it as a g/d. Mean values were 13.65 and 8.84 g/d, respectively. This may be due to higher CP content and its higher digestibility in alfalfa than that in G2 group. However, animals in G2 group had high value of NB than that in G1 group when expressing it as a percentage from nitrogen intake. Mean values were 55.47 and 41.20 %, respectively. These results are in agreement with those of Shawket et al., (2005) and Fayed et al., (2010).
Table 3: Nitrogen balance in Shami goats as affected by roughage type
Ruminal parameters:
From the data of Table (4) animals of G2 group had insignificant higher value of ruminal ammonia concentration more than those of G1, the values were 42.75 and 36.37 mg/100 ml, respectively. Mehrez et al., (2001) and Hassan (2009) recorded that ruminal microbial protein synthesis needs a sufficient supply of nitrogen to reach maximal efficiency. Animals fed on berseem (G1) had higher (P<0.05) volatile fatty acids concentration more than those fed salt plant mixture (G2); the values were 9.88 and 4.77 m. equiv. /100 ml, respectively. These results might be due to higher salt and lower energy contents of atriplex which reducing the rumen turnover time with subsequent influences on rumen physiology and metabolism (Warner and Casson; 1992 and Konig, 1993) and reduce the production of VFA's in the rumen (Shawket and Ahmed, 2009). Similar results were reported by Abou'l Ella et al., (2005) who reported that total <0.05) volatile fatty acids concentration more than those fed salt plant mixture (G2); the values were 9.88 and 4.77 m. equiv. /100 ml, respectively. These results might be due to higher salt and lower energy contents of atriplex which reducing the rumen turnover time with subsequent influences on rumen physiology and metabolism (Warner and Casson; 1992 and Konig, 1993) and reduce the production of VFA's in the rumen (Shawket and Ahmed, 2009). Similar results were reported by Abou'l Ella et al., (2005) who reported that total VFA's and ammonia -N concentrations were significantly increased with further increases in the nutritive values of the diet.
Table 4: Effect of feeding salt tolerant plants on Rumen ammonia (NH3-N, mg/100 ml) and volatile fatty acids (VFA´s m.equiv./ 100 ml) concentration of Shami goats.
Live body weight:
Data in Table (5) showed that there was no significant differences between animals fed berseem or those fed salt tolerant plants mixture regarding final body weight (30.36 vs. 31.00 kg) or body weight changes (5.07 vs. 6.00 kg). In similar, working on sheep, Shaker (2014) reported that feeding a mixture of salt tolerant fodder crops (Atripex nummularia, Pearl millet and Sorghum bicolor) resulted in insignificant differences in body weight with animals of control group. This slight increase in final body weight of animals of G2 group might be due to the increase in water intake. Similar trends were recorded by Shawkat et al., (1988).
Feeding animals on mixture of salt tolerant plants resulted in higher (P<0.05) percentage increase from initial body weight (26.53 vs. 20.67%) and average daily gain (40.00 vs. 33.81 g) than those fed on berseem. The increase in average daily gain might be due to the reduction in dry matter intake from roughage with increasing the substitution level from concentrate. The conclusion is that feeding female Shami goats with salt tolerant plants mixture do not affect their body weight gains. ><0.05) percentage increase from initial body weight (26.53 vs. 20.67%) and average daily gain (40.00 vs. 33.81 g) than those fed on berseem. The increase in average daily gain might be due to the reduction in dry matter intake from roughage with increasing the substitution level from concentrate. The conclusion is that feeding female Shami goats with salt tolerant plants mixture do not affect their body weight gains.
Table 5: Live body weight (BW) changes of female Shami goats as affected by on salt tolerant plants.
Changes in climatic elements during different physiological periods:
Changes in climatic elements are shown in Table (6). Ambient temperature (AT) fluctuated from 15.33 to 16.00 °C at 08.00 h, while at 14.00h fluctuated from 23.33 to 26.33 °C all over the experimental period.
Relative humidity (RH %) showed revers trend to that of AT. Maximum level (58.67%) was reached during mid-pregnancy period at morning, while the lowest (30.33%) occurred during late pregnancy at 14.00h. Infrared radiation from surroundings lied between 15.57 to 30.46 °C.
All these climatic elements were within the neutral range; hence experimental animals did not exposed to climatic stress. Accordingly, any changes in thermo respiratory responses would be due to diurnal variation, physiological status or metabolic heat production.
Table 6: Diurnal variation of ambient temperature (AT), relative humidity % (RH) and infrared radiation during different physiological periods.
Effect of feeding salt tolerant plants on thermo respiratory responses:
a) Rectal temperature °C (RT):
Rectal temperature was affected significantly by type of feeding, physiological stage and diurnal variation. Feeding the mixture of salt tolerant plants resulted in rising RT of does at morning. This reflected higher metabolic heat production of these does, and indicated that the feeding mixture provides more energy to the animals. From Table (1), the mixture of salt plants contained higher NFE than berseem hay (52.54 vs. 44.48 %). As a result of low RT at morning that exhibited by does of group G1, diurnal variation (DV) was higher (P<0.05) than that of animals fed salt plants mixture (0.60 vs. 0.26 °C). Accordingly, TF X DV interaction was significant><0.05) than that of animals fed salt plants mixture (0.60 vs. 0.26 °C). Accordingly, TF X DV interaction was significant.
Rectal temperature showed the highest values at mid and late pregnancy, especially at 14.00h. This trend reflects also high metabolic heat production during late pregnancy.
b) Skin Temperature °C (ST):
Skin temperature was affected significantly only by diurnal variation (DV), where it increased by about 5 °C from morning to afternoon. This difference was due to the decrease in ST at morning as a reflection to low AT along the experimental period between 15 to 16 °C (Table 6). The highest overall mean was recorded at mid pregnancy (32.63 °C). The highest DV was 6.31 °C during LP in G1 while was 7.30 °C during EP in G2. Accordingly, there was a significant interaction DV X PS. In conclusion, ST was affected mainly by environmental temperature and the rate of metabolic rate, but not by type of feeding.
c) Coat temperature °C (CT):
Coat temperature was significantly affected by physiological stage (PS) and diurnal variation (DV). Diurnal variation in CT reflected the effect of AT. However, DV in CT increased during pregnancy in both groups with the highest values (10.84 and 9.66 °C) at late pregnancy. This made significant interaction DV X PS. Like skin temperature, CT affected mainly by environmental temperature and the rate of metabolic rate, but not by type of feeding. Group 1 induced increase in coat temperature, infrared radiation and respiration rate at 14:00 h by 27.13 ºC, 26.06 ºC and 33 ºC, respectively compared with 8:00 h. However, it showed no significant effect in rectal temperature and skin temperature at 14:00 h compared with 8:00 h. Coat temperature, infrared radiation and respiration rate showed significant increases at 14:00 h by 27.6 ºC, 29.13 ºC and 32.33 ºC, respectively compared with 8:00 h, but it showed no significant effect on rectal and skin temperature at 14:00 h compared with 8:00 h (Table 7).
When rectal temperature was measured during gestation, the result revealed that pregnancy caused significant increase in rectal temperature and the value increased with the course of gestation. The value increased at the last stage of pregnancy slightly above the limit of 39 °C recorded by Igbokwe (1993) to 41.22±0.5 °C, thus, suggesting that pregnancy induces varying degree of stress in goat during pregnancy.
d) Infrared radiation °C (IR):
Infrared radiation is the heat energy that emits from animals due to its higher temperature than that of the environmental one. Animal temperature is a reflection to the heat energy he gained or loss from the surrounding environment in addition to the inner metabolic heat production. Accordingly, the CT was significantly affected by all sources of variation (TF, PS and DV). The interaction DV X PS was significant due to, in both experimental groups, does exhibited the highest DV of IR during late pregnancy (10.87 and 9.05 °C).
e) Respiration rate acts/min (RR):
Respiration rates of does in both experimental groups were significantly affected by PS and DV. The interaction between these two sources (DV X PS) was significant. Consequently, type of feeding had no effect on RR. The diurnal variation did not reflect any environmental heat stress since all RR were within the normal range. Only metabolic heat production during pregnancy exerted effect on RR.
Hakiri and Health (1988) stated that in goats, physiological parameters especially respiratory rate under thermo neutral conditions is about 25 respirations per minutes. They added that variation may occur with varying physiological condition such as pregnancy, body fat and strenuous physical activities.
In the present study, the variations recorded for respiratory rate are consistent with previous studies indicating that this parameter can display homeostatic physiological variability during late pregnancy and the first four weeks postpartum (Davey et al., 1998). Our observations are in accordance with those of Davey et al., (1998), where we noted a higher respiratory rate in the two group both at the mid and the late pregnancy.
In conclusion, the results of thermorespiratory responses indicated that the mixture of salt tolerant plants provided does with more energy, but did not exert any stress on body thermal balance. However, experimental does were affected more by the metabolic heat production during mid and late pregnancy.
Table 7: Thermo respiratory responses of Shami goats as affected by feeding salt tolerant plants during different physiological status.
Effected of feeding salt tolerant plants on blood picture:
Feeding salt tolerant plants mixture resulted in significant decrease in RBCs, WBCs, PCV%, Hb concentration and MCHC (Table 8 and Figure 1). The level of MCH (pg) also decreased but insignificantly. However, MCV (fl) increased insignificantly by feeding salt plants. This increase in MCV might reflect the increase in intracellular fluids to dilute the salt concentration to keep the intracellular osmotic pressure. Increasing intracellular fluids due to salt stress led to a dilution of the cell contents hence the decrease of Hb concentration. The decrease in cell counts and PCV% might also indicate the increase in extracellular fluids due to salt stress. However, the majority of blood constituent levels were consistent with the general normal ranges reported for goats (Ismail et al., 2008).
The level of RBCs count increased (P<0.05) with advancing pregnancy, and MCHC (%) increased (P><0.05) to reach its peak level at mid-pregnancy then decreased to the initial level at late pregnancy. As a result, Hb (g/dl) increased (P><0.05) and followed the trend of MCHC. Reversely, the levels of WBCs, MCV and MCH decreased (P><0.05) with advancing pregnancy><0.05) to reach its peak level at mid-pregnancy then decreased to the initial level at late pregnancy. As a result, Hb (g/dl) increased (P<0.05) and followed the trend of MCHC. Reversely, the levels of WBCs, MCV and MCH decreased (P><0.05) with advancing pregnancy.><0.05) and followed the trend of MCHC. Reversely, the levels of WBCs, MCV and MCH decreased (P<0.05) with advancing pregnancy.><0.05) with advancing pregnancy.
The variation of blood parameters with advancing pregnancy might indicate physiological adjustment to increased fetus needs to nutrients and oxygen supply. Mbassa and Poulsen (1991) and Waziri et al., (2010) stated that mean values of corpuscular elements can vary in different physiological stages, age groups and breeds.
Table 8: Means of blood picture characteristics of Shami goats as affected by feeding salt tolerant plants during different physiological status.
G1, animals fed on berseem (alfalfa) + CFM (Control group); G2, animals fed on a mixture of fresh Atriplex (50%) + sorghum (25%) + pearl milt (25%) Fig. 1: Means of blood picture of Shami goats as affected by feeding salt tolerant plants during different physiological status.
Conclusion:
It could be concluded that use of salt tolerant plants as animal feeds in salt lands could be a suitable option for alleviating the desertification problems and providing alternative good feed resources, particularly in dry seasons when the other conventional forage resources are shortage. Also, we can use salt tolerant plants as non-traditional diet without any adverse effects on hematological and physiological performances of Shami goats under desert conditions.
This article was originally published in Research Journal of Animal and Veterinary Sciences, 9(2): 8-15. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. 
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