In desert area of Egypt, the shortage of ruminant feeds especially in summer and early autumn seasons is the main challenge to increase indigenous animal production and improve livestock productivity (Mansour and Al-Zahar, 2018). In arid and semi-arid regions such as South Sinai, animal husbandry, as the main income resource for pastoralists, is mostly based on the natural vegetation for rearing small ruminates (Squires and El Shaer, 2016). Degradation of the rangeland is evident in many parts of desert Egypt as a result of overgrazing, low erratic rainfall and long drought periods (El-Shesheny et al., 2014). So, in late years, the International Center for Bio saline Agriculture (ICBA), UAE, and Desert Research Center, Egypt, collaborated to improve livelihood and income of the local poor people in marginal lands by cultivating salt-tolerant plants as fodders for their livestock (El Shaer, 2010). Natural fodder shrubs such as Atriplex nummularia and some common cultivated salt-tolerant fodder plants e.g. pearl millet and fodder beet, might be used to fill the gap in feed production in saline and dry areas (Helal et al., 2018a).
Oldman saltbush (Atriplex nummularia Lindl.) has received increasing interest as livestock forage especially in arid zones because it’s adapted to drought and water and soil salinity. Oldman saltbush produces important consumable biomass in areas where other crops cannot grow (Ben Salem et al., 2010).
Pearl millet (Pennisetum glaucum, L. R. Br.) is considered as potential salt-tolerant grass species and good quality fodders for sheep in Egypt (Anon, 2009).
Fodder beet is not a sensitive crop; it can tolerant the unfavorable conditions of reclaimed soils, and high water irrigation salinity (Heuzw et al., 2015). Moreover, it is typically high in total digestible nutrient (75.94%) as reported by Gabra and Gad (1999) but low with crude protein values of 6% (ElEissawy et al., 2011), high yielding in terms of nutritive value and low input utilizing farm resources (Mansour and Al-Zahar, 2018).
Many procedures have been used to utilize and enhance desert feed resource (e. g. ensiling). Ensiling salt-tolerant plants (STP) with other feed ingredients appeared to be the most convenient processing method under the prevailing conditions of aridity in Egypt. In addition, processing STP as silage form led to improve the quality of halophytes and enhanced their acceptability for small ruminants (El Shear, 2004).
In Egypt, there are about 5.6 million heads of different breeds of sheep (El-Far et al., 2014). Barki sheep is one of three main breeds in Egypt. About 470,000 heads of this breed are maintained along the desert rangeland areas of Egypt (El-Bassiony 2016), out of which 300-350 thousand weaned male lambs may be produced yearly (Ibrahim 2018). So, this study aimed to assess the effect of ensiling mixture of salt-tolerant plants on male lamb's performance during growing period.
MATERIALS AND METHODS
Experimental location: The present study was conducted in South Sinai Research Station which localized in Ras Sudr and belongs to Desert Research Center (DRC), Ministry of Agriculture and Land Reclamation, Egypt.
Silage preparation and making: Three salt tolerant plants (STP), Atriplex nummularia (AN), fodder beet (FB) and Pearl millet (PM) were used for processing the experimental silage mixture. Both of AN and PM were collected and chopped to 3-5 cm. The fodder beet roots were chopped using fodder beet chopping machine. The chopped parts were mixed where AN represented 50%, FB 35% and PM 10% and the final mixture was sprayed with 5% molasses and ensiled as described by Abou El Nasr et al., (1996). The salt tolerant plants silage (STPS) was fed to the experimental animals after 42 days of making silage
Animals and rations: Sixteen male Barki sheep (31.42 ±1.79 kg and 4 months age) were used in this study. Animals were randomly divided into two equal groups (8 each). All experimental lambs were fed concentrate feed mixture (CFM) as 60% percentage for total rations. While, the roughage part was diffed where the 1st lambs group (T1) received 40 % Berseem hay (BH) and consider as a control group. The 2nd lambs group (T2) fed ad liptum salt tolerant plants silage (STPS).
All experimental animals were weighed at the starting of the experiment and then biweekly till the end. The amounts of offered rations were adjusted according to lamb's weight according to Kearl (1982). Clean fresh water was offered twice daily. The growing experiment lasted for 120 days.
Digestibility trails: At the end of growing period, digestibility trail was assessed. Twelve animals (6 animals/ group) were placed individually in metabolism cages for 14 days as an adaptation period followed by 7 days as collection period. During the collection period, voluntary intake of each diet was determined and total feces weight and urine volume were recorded daily and samples represented one tenth of the voided feces and exerted urine were taken daily just after collection. Samples of feed, refusals and feces were dried at 65 °C for constant weight and ground to pass through a 1.0 mm mach screen and kept for analysis. Feces and urine samples were composited separately for each animal and stored for chemical analysis. Urine samples were stored in tight bottles containing sulfuric acid (1:1) to capture NH3-N. Drinking water was recorded and offered at 12.00 pm and feed intake was offered at 8.00 am. At the end of the collection period, samples of rumen liquor were taken at zero time, 3 and 6 hours post feeding through stomach tube, then filtered through two layers of mesh cloth and were stored at (-18 °C) to determine rumen ammonia nitrogen (NH3-N), pH and total volatile fatty acid (VFA’s). Also blood samples were withdrawn from jugular vein at zero time before feeding and were stored at (-18 °C) to determine total proteins (TP), albumin (AL), globulin (GL), urea-N and creaatinine. All parameters of blood picture (erythrocytes cell counts, RBCs; white blood cells, WBCs; hematocrit, Hct; hemoglobin, Hb; mean corpuscular volume, MCV; mean corpuscular hemoglobin, MCH and mean corpuscular hemoglobin concentration, MCHC) were measured in whole blood using blood counter apparatus model Rayto Product RT-7600 Auto Hematology Analyzer.
Analytical methods: Proximate analysis of CFM, BH, STPS, fecal samples and Ammonia nitrogen in the rumen fluid were determined according to AOAC (2007) in Animal Nutrition Laboratory of Desert Research Center. Total volatile fatty acids (TVFA’s) were determined according to Warner (1964).
Statistical analysis: Data obtained in this study was statistically analyzed by one way of variances according to SAS (2004) and the statistical model was: - Yij = µ +Ti +eij, Where: Yij = experimental observation, µ = overall mean, Ti = effect of treatment, eij = experimental error.
Differences between means were compared by Duncan's multiple range test of Duncan (1955).
RESULTS AND DISCUSSION
Chemical composition of the experimental roughages and CFM: The present results revealed wide variations in chemical composition of the experimental roughages. It can be seen that STPS had lower contents of DM, OM, CP, NDF and ADF than BH. However, STPS was higher than BH in ash content by 46.5% (Table 1). These results are in agreement with those obtained by Abd El-Rahman (2008) and El Shaer (2010) who reported that, most of halophytes are naturally characterized by high ash content as they tolerate high salt concentration in soil.
Calculated TDN for STPS was higher than BH which may be due to the existence fodder beet and molasses in STPS which features with high energy content (El-Eissawy et al., 2011). Moreover, El Shaer (2010) concluded that some halophytes seemed to be nutritious based on their moderate nutritive value which can meet the maintenance nutritional requirements for ruminants (Kearl, 1982).
Chemical analysis of CFM had content 13.8% and 10.8% for crude protein and fiber, respectively. Also it had moderate nutritive value as TDN (%) according to chemical composition of its included traditional ingredients.
Voluntary feed intake and digestion coefficient: Data in Table (2) showed that roughage intake as g DM/ kg BW was lower (P< 0.05) for STPS group than that of control group, with values being 13.61 vs 18.26 g/kg BW. The same trend was observed for roughage CP intake. These findings may be due to high ash content (Fayed et al., 2010 and Hassan, 2009). Also, Attia-Ismail (2015) reported that halophytes and salt tolerant fodders contain high ash, high fiber content and low protein, which may decrease roughage intake.
Animals fed STPS tended to consume comparable amount of total DMI but in general lower than that fed the control ration (Table 2). Commonly, this result indicated that the silage could replace the berseem hay in the fattening rations. This finding is in agreement with those obtained by Abdul-Aziz et al. (2001).
Digestion coefficient of DM, CP, CF, NDF and ADF are shown in Table (2). Crude protein digestibility was higher (P< 0.05) for STPS group than BH group. This result may be owing to that STPS provided more readily available energy which improves protein utilization (Mansour and Al-Zahar, 2018).
In general, lambs fed on STPS recorded acceptable digestion coefficient compared to lambs fed control group (Table 2). These results may be attributed to that fodder beet ration had the highest value of NFE and the lowest CF value (Mansour and Al-Zahar 2018), as well as fodder beet is characterized by high sugar and starch contents resulting in high nutrient digestion and most likely supporting microbial growth (Helal et al., 2012 and De Brabander et al., 1999).
Water utilization: Water utilization (free drinking, fecal, urinary and total water execration) as affected by type of experimental rations is shown in Table (3). There was a significant difference between the experimental groups in free water intake, being values 123.4 and 208.3 ml/kg BW0.82 for control and STPS groups, in order. Obviously, the high moisture content led to the low water intake as shown in STPS group. Such trend is close to that obtained by Ben Salem et al (2010) who reported that sheep or goats receiving the mixture of saltbush and cactus (are low nitrogen and fiber but high in sugars) would need less drinking water as compared to those fed on saltbush alone or supplemented with dry feedstuffs (i.e. concentrate feeds) and the values ranged between 0.5 and 7 L/day.
Free water intake was higher (P< 0.05) for control than STPS group with values being 3.24 and 2.20 ml/ g DMI, respectively. This result is in agreement with those obtained by Abou El-Nasr et al., (1996) who reported that values of free water intake ranged from 2.09 to 3.90 ml/g DMI for sheep fed different forms of saltbush plants
Urinary, fecal and total water execration showed the same trend of free drinking water, hens, control group had higher (P< 0.05) for urinary, fecal and total water execration than STPS group (Table 3).
Lower water execration in STPS than control group may be due to low free water intake. The similar results was observed by Pearce et al. (2010) who reported that increasing water retention for sheep grazed salt bush as a results of the highest concentrations of vitamin E in the muscle of the salt bush-grazed and aiding the retention of water.
Ruminal parameters: Data in Table (4) declared that, there were no significant differences in pH values at 0, 3 and 6 hrs. post-feeding as a result of feeding STPS for lambs. In similar, Helal et al. (2018a) reported that ruminal pH levels didn't differ significantly between animals fed mixture of halophytes or control. Generally, the mean pH values of rumen liquor in the present study are within the ranges reported by Suharti et al. (2015) being 6.8- 7.0.
The degree of acidity of rumen fluid is the main variable of rumen fermentation as it can alter the type of fermentation Orskov and Ryle (1990). Moreover, Attia-Ismail (2015) reported that cellulolytic bacteria reduced when the pH begins to fall below 6.0.
Values of ruminal NH3-N concentration (Table 4) were not affected (P< 0.05) by the experimental rations although the concentration increased with increasing the time before feeding up to 6 hrs after feeding for all animals.
Commonly, NH3-N concentration of rumen fluid in the present study remained within the normal range under normal conditions from 8.5 to 30 mg/100ml of rumen fluid (McDonald et al., 2002).
The concentrations of TVFA were not significantly affected by the experimental rations (Table 4). The results in the current study were in agreement with that of Eid (2003) who found that, values of TVFA were not significantly affected when sheep fed silage of halophytic plants mixture or control ration. On the other hand, Masters et al. (2009) reported that animals fed salt rations led to reduction of TVFA production.
Generally, ruminal TVFA values obtained in this study were within the normal levels (3.2 - 7.47 meq/100 ml RL), which reported by Yossef (1999).
Blood biochemistry: Blood TP of lambs fed STPS was lower (P< 0.05) (5.68 g/dl) than that of control ration (6.66 g/dl) (Table 5). This finding may be explained as lower crude protein content of STPS compared to BH as shown previously in Table (1). These results were in agreement with those reported by Ibrahim et al. (2018) who reported decreases (P< 0.01) in TP in ewes and their lambs which fed STP could be assigned to lower crude protein percentage in ration of STPS than BH. Furthermore, El-Shaer et al. (2005) and Fayed et al. (2010) attributed the lowest values of total proteins, albumin and globulin for lambs fed STPS to high salt content of STPS compared to BH.
In this respect, Abdel-Ghani et al. (2011) recorded a positive correlation between dietary protein and level of serum TP in sheep. Average values of blood TP of animals fed experimental rations were within the normal range (5.84 -7.31 g/dl) of small ruminates under salt plants feeding conditions according to Helal et al. (2018b). On the other hand, values of AL, GL and AL/GL ratio were not significantly affected by the experimental rations. These results were in agreement with results reported by El-Essawy et al. (2011) who found no significant differences in these parameters when rams fed the FB plus alfalfa or FB plus Atriplex nummularia.
Generally, blood biochemistry parameters such as TP, AL and GL has a great importance as good indicators of nutritional status (EL-Gohary et al., 2017). The present results showed clearly that feeding STPS didn’t cause any side effects and all values of blood biochemistry were within the normal ranges and the animals of the present investigation were in good nutritional status.
The results of blood urea and createnine concentrations clarified that feeding STPS did not affect the kidney function (Table 5). The present results are in accordance with Eid (2003) who reported insignificant differences between sheep fed different roughage (silage of halophytes plants mixture or BH). The obtained values of urea nitrogen concentration were within the normal levels and had no adverse effect of kidney function in all animals groups (Hanafy et al., 2007). Similar insignificant results were obtained with blood createnine concentration (Table5). On the other hand, Shaker et al. (2014) reported that goats fed STP mixture decreased (P< 0.05) blood createnine concentration.
In general, the revealed values for blood createnine concentration (1.19 - 1.27mg/dl) were within the values (1.1 – 1.9 mg/dl) reported by Abdul and Daniel (2013) and Amuda and Okunlola (2018).
Blood picture: Results of blood picture parameters except for WBC's (Table 6) were not affected (P< 0.05) by the experimental rations. WBC's was decreased (P< 0.05) for STPS group compared to control group. These results were in agreement with those reported by Bhatti et al. (2009) who found that WBC's was significantly decreased for buffalo heifers fed roughage contained 66.5 % ( Pennisetum purpurium plus Atriplex amnicola ) compared with BH.
Feeding STPS or BH resulted in insignificant differences in RBC’s (Table 6). This result agreed with that reported by Fayed (2009) who found no significant changes in RBC’s for sheep fed halophyte plants.
The comparable values of Ht, Hb, MCV, MCH and MCHC resulted by feeding lambs on STPS compared with BH emphasis that STPS could be successfully incorporated in rations of sheep in the desert area without any adverse effects on lambs. All values recorded for the previous parameters are within the normal ranges as reported by Amuda and Okunlola (2018). In addition, these results were in agreement with those obtained by Khalasi et al. (2010). Also, Alhadrami and Dakheel (2005) reported that feeding Awassi sheep high STP has no signs of illness or loss of appetite.
Lambs performance: Weights of fattened lambs are present in Table (7) and didn’t appear any significant (P< 0.05) differences between groups. Although there were no significant effects (P> 0.05) on total or daily BW gain, there was a trend that animals fed BH grew slightly better than those fed STPS. Average daily gain for control group was higher by 15.6% than STPS group.
These findings are in line with the results reported by Abu-Zanat (2005) who observed a significant effect of forage type on growth rate of Awassi lambs. Where lambs were fed alfalfa hay diet showed higher growth rate than those lambs fed ration containing Atriplex alone or mixed with alfalfa hay.
Generally, the obtained average daily gain by STPS was lower than that obtained in earlier studies (Gabr, 2002 and Eid, 2003) while Ghandour et al. (2014) found that the average daily gain ranged from 67.22 to 144.22 gm for lambs fed CFM plus different roughage (Acacia hay or BH, respectively). Also, Al Khalasia et al. (2010) showed that average daily gain ranged from 68.2 to 96.3 for lambs fed rations containing sorghum fodder irrigated with water containing three different concentrations of salt (3, 6 or 9 dS/m).
Economical evaluation: The obtained findings revealed that the feed conversion expressed as kg DMI/kg gain were 11.46 and 12.86 for control and STPS groups, respectively. This result was in agreement with those obtained by El Shaer (2004) who reported that feed conversion ranged from 14.0 and 14.2 kg feed/ kg gain for sheep fed BH or halophytes silage, respectively. Also, Abdou et al. (2011) reported that feed conversion was 12.16 kg feed/ kg gain for goats fed BH plus CFM and 15.27 kg feed/ kg gain for goats fed Atriplex nummularia plus different desert concentrate feeds or halophytes silage, respectively.
Besides, the obtained resulted demonstrated that the highest feed cost per kg gain was recorded for control group due to higher price of BH (3500 LE/ton), however, the ration of STPS had lower feed cost (2000 LE/ton).
In spite of the highest total gain in control group, the highest price of BH and highest cost of kg gain reflected negatively return from selling live weights. On the other hand, the lowest total gain and the cheapest price of roughage for STPS group reflected positively (higher by 24%) return from selling live weights. Also, STPS group resulted in high net revenue by 24% over than that resulted by BH.
From aforementioned results, it could be concluded that, ensilage mixture of salt tolerant plants such as Atriplex nummularia, Pearl millet with fodder beet could be used successfully and safely for feeding lambs with no health challenges to the animals. Utilization of STPS could be considered as an attempt to reduce feed shortage and feeding cost and to enhance the economical feed efficiency in the arid and saline conditions prevailed in Southern Sinai, Egypt.
This article was originally published in Egyptian J. Nutrition and Feeds (2020), 23(3): 385-395.