Antonio

Trop Anim Health Prod (2011) 43:1297–1309 DOI 10.1007/s11250-011-9851-z

SI FAT TAILED SHEEP

Alternative feedstuffs and their effects on performance of Awassi sheep: a review Mofleh S. Awawdeh

Accepted: 12 April 2011 / Published online: 22 April 2011 # Springer Science+Business Media B.V. 2011

Abstract Fat-tailed sheep (FTS) is a group of breeds characterized by large (fatty) tails that it is commonly distributed in Africa, Middle East, Pakistan, and to a lesser extent in other countries. Awassi, a common FTS breed in many Mediterranean countries, is adaptive and suitable to live in harsh conditions of the arid and semiarid areas. One of the main constraints for sheep industry in those areas is the limited supply and variable quality and quantity of feedstuffs. Using several alternative feedstuffs (AF) has been a common practice to decrease production cost of Awassi sheep industry in those areas. The appropriate AF to be used is determined by several animal and feed factors. These AF includes, but not limited to, unconventional feedstuffs, agricultural byproducts, and agro-industrial byproducts. A good body of literature about the use of AF and the effects of such use on performance of Awassi sheep is available. Some of these AF have been shown to be safely used in Awassi diets with no detrimental effects on sheep performance or health and, thus, recommended to lower the production cost. Other AF has controversial effects and recommendations. This paper reviews the effects of using AF on performance of Awassi ewes and lambs. Effects on intake, nutrient digestibilities, growth rate, and carcass characteristics of lambs and on intake, nutrient digestibilities, body weight change, milk yield, and milk composition of ewes will be emphasized. Recommendations and limitations for using AF will also be briefly discussed.

M. S. Awawdeh (*) Department of Pathology and Animal Health, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan e-mail: [email protected]

Keywords Alternative feeds . Awassi sheep . Fat-tailed sheep . Performance List of ADF AF BV CF CP DM DMI EE FCR FTS GE ME NDF OC OM PJP SBM TP

abbreviation Acid detergent fiber Alternative feedstuffs Bitter vetch Crude fiber Crude protein Dry matter Dry matter intake Ether extract Feed conversion ratio Fat-tailed sheep Gross energy Metabolizable energy Neutral detergent fiber Olive cake Organic matter Prosopis juliflora pods Soybean meal Tomato pomace

Introduction Sheep industry is a very important, and in some countries, the main sector of livestock industry in Mediterranean countries. In addition to its countries of origin (Iraq, Jordan, Palestine, Syria, and Turkey), Awassi is a common sheep breed in other Mediterranean countries (i.e., Lebanon) and the most common breed in southwest Asia (Epstein 1985; Galal et al. 2008). In fact, Awassi is the main sheep breed in Iraq and Syria (Galal et al. 2008; Shomo et al. 2010) and the only native breed in Jordan (Hailat 2005) and Palestine

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(Galal et al. 2008). Awassi breed has spread from its countries of origin to other countries in all continents of the world for breeding purposes. Galal et al. (2008) listed about 40 of such countries and the list is probably increasing. Information about origin, visual and production characteristics, and genetics of Awassi sheep have been covered by several authors (Epstein 1985; Hailat 2005; Galal et al. 2008) and will not be further discussed in the current review. Awassi sheep has good milk production and growth abilities (Galal et al. 2008) even in harsh conditions of the arid areas. The hardiness of Awassi breed allowed their members to be fully adapted to environmental stressors (i.e., hot weather, humidity, diseases, and parasites) of the semiarid and arid regions (Epstein 1985). Additionally, Awassi sheep have good ability to adapt to fluctuations in nutrition and management. In general, sheep in Mediterranean region are raised in extensive, semi-extensive, or intensive systems (Hailat 2005). As shifting toward intensive system is increasing (due to economical and social reasons) or at least encouraged (Shomo et al. 2010), the need for extra conventional feed supply is also increasing. In all systems, the limited supply and fluctuations in quantity and quality of feedstuffs are among the major factors that constrain the sheep industry in Mediterranean countries. Additionally, feeding cost is the major constraints of Awassi lamb fattening systems in Syria (Hartwell et al. 2010) and other Mediterranean countries. Thus, using nonconventional feedstuffs (alternative feedstuffs; AF) has been a common practice to decrease production cost of sheep industry in those areas. However, the challenge for animal nutritionists is to use such AF without negatively impacting animal health, performance, and quality of products. With reference to Awassi breed, the objective of this paper is to review the use of different AF in sheep industry and the effects of such use on sheep (ewe and lambs) performance (intake, digestibility, growth rate, milk yield, etc.).

Production system Sheep are generally raised under one of three systems: extensive (migratory), semi-extensive (semi-migratory), or intensive (Hailat 2005; Shomo et al. 2010). The proportion (number) of sheep in each system varies among countries depending on social and economical factors, pasture and range availabilities, and others. In Jordan, approximately 20–30%, 45–70%, and 10% of sheep industry are distributed among extensive, semi-extensive, and intensive systems, respectively (Hailat 2005). The dependence on supplementary feeding is essential in all systems and inversely related to the level of extensiveness. Such dependency is becoming critical as switching to intensive

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systems is expanding and/or encouraged (Shomo et al. 2010).

Types of AF and their effects on sheep performance Several factors determine which AF is appropriate to be used in sheep feeding. These include factors related to animal and feed. Animal factors include sheep breed, physiological and production stages, production level, etc. Feed factors relate to AF properties in terms of availability, chemical and nutritive value, price, and effect on animal performance. Additionally, composition of the basal diet is another feed factor that determines which AF to be selected. For the sake of simplicity, we will classify AF into different categories (protein, energy, fiber, and mixed sources) based on the chemical composition of that AF and/or the chemical composition of the dietary ingredient that the AF replaced in the basal diet. This classification emphasizes that knowing the chemical composition of any potential AF is the first and most important step for a successful inclusion of any AF in animal’s diet. Table 1 can serve as a tentative guide for available chemical composition of different AF discussed in this review. Readers should be aware that given values can vary significantly as will be discussed in “Constraints and limitations” section. Alternative energy sources and their effects on sheep performance Different alternative energy sources have been evaluated and successfully utilized in feeding Awassi sheep at different production (physiological) stages. Studies on alternative energy sources and their effects on Awassi sheep performance are summarized in Table 2. Dried date pulp was included in increasing levels (0%, 15%, 30%, or 45%) by replacing barley in diets for finishing Awassi lambs (Al-Ani et al. 1991). The authors demonstrated that all inclusion levels did not affect dry matter intake (DMI) of lambs but the higher levels (≥30%) depressed nutrient (dry matter, DM; organic matter, OM; neutral detergent fiber, NDF; and acid detergent fiber, ADF) digestibilities. Growth rate of lambs fed diets containing 15% dried date pulp tended to increase but decreased in those containing 45% dried date pulp. The 15% was the recommended inclusion level because it resulted in improved growth rate and feed conversion ratio. Although olive cake (OC; byproducts after extraction of oil from olive fruits) is considered low quality feedstuff, Al Jassim et al. (1997) successfully included urea-treated OC at 0%, 10%, 20%, or 30% in diets for finishing Awassi lambs, by replacing barely, without affecting growth rate or efficiency. However, nutrient (DM, OM, NDF, ADF, and energy) digestibilities were linearly depressed by increasing

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Table 1 Approximate chemical composition of alterative feedstuffs discussed in this article Reference

Alternative feedstuff

DM%

OM%

CP%

NDF%

ADF%

EE%

Al-Ani et al. 1991 Al Jassim et al. 1997 Al Jassim et al. 1998 Obeidat et al. 2008 Abdullah and Abddel hafes 2004 Awawdeh et al. 2009a Obeidat et al. 2011a Obeidat et al. 2011b

Dried date pulp Olive cake Acorn P. juliflora P. juliflora Yellow grease Carob Dried poultry litter

80.0 50.0 53.7 92.6 NR 99.3 96.2 88.6

78.9 95.2 97.2 95.1 NR NR 96.0 84.2

4.9 4.8 2.9 NR 12.6 NR 9.2 27.2

40.7 73.2 49.8 32.9 NR NR 21.3 33.4

34.3 56.8 26.4 20.5 NR NR 15.0 21.5

NRa 9.8 2.4 2.1 NR NR NR 2.2

Harb 1986a Harb 1986b Bhattacharya and Harb 1973

Dried tomato pomace Dried Destoned olive cake Dried citrus pulp

90.8 NR 82.9

NR NR NR

21.5 5.6 8.1

72.7 NR NR

49.1 68.8 NR

4.7 3.2 3.2

Harb, and Shourafa 1982 Obeidat et al. 2009 Omar 2002 Irshaid et al. 2003 Obeidat and Aloqaily 2010 Muwalla et al. 1995

Dried poultry litter Sesame meal Sesame meal Sunflower meal Sesame hulls Dried poultry litter

90.8 92.8 95.7 92.7 93.3 92.5

81.7 93.6 92.5 92.9 88.0 62.4

27.8 46 23.7 31.2 25.8 11.7

NR 15.8 NR 46.6 23.0 NR

NR 8.5 34.5 32.3 15.8 NR

2.3 11.7 28.1 1.5 17.6 3.0

Abdullah et al. 2010 Haddad 2006 Harb, and Shourafa 1982 Awawdeh (unpublished data) Abu-Zanat and Tabbaa 2006 Abo Omar 2001 Harb and Shourafa 1982 Darwish and Harb 1996

Bitter vetch seeds Bitter vetch seeds Brewers grain Sun-dried olive cake Saltbush Corrugated cardboard Dried olive cake Banana leaves

90.7 NR 96.0 92.6 92.5 NR 94.8 24.6

94.3 92.0 93.2 96.4 74.8 99.6 92.7 NR

23.1 21.9 21.4 8.3 12.8 1.3 6.0 6.5

21.3 9.7 NR 53.5 40.7 NR NR 66.0

6.9 9.1 NR 34.3 27.5 NR NR 46.1

1.1 NR 1.8 11.3 NR 0.7 8.5 NR

Additional notes

GEb =5.4 GE=4.2 MEc =3.2 ME=6.6 Tannins=6.1%

CFd =57.7 CF=11.2 GE=4.0 CF=17.3 ME=2.9 CF=12.4 CF=32.1 ME=3.9 CF=11.0 ME=2.2

CF=10.4 GE=6.6 ME=2.2 CF=69.9 CF=43.5 Tannins=0.6%

All compositions are on DM basis unless indicated DM dry matter, OM organic matter, NDF neutral detergent fiber, CP crude protein, ADF acid detergent fiber, and EE ether extract a

NR not reported in corresponding reference

b

GE gross energy (Mcal/kg)

c

ME metabolizable energy (Mcal/kg)

d

CF crude fiber (%)

the inclusion level of OC. From Al Jassim et al. (1997), it appears that the 20–30% is the appropriate inclusion level because the depressions in digestibility became apparent at the 30% level. Previously, de-stoned OC was included in diets for finishing Awassi lambs in increasing levels (from 0% to 40%) by replacing barley (Harb 1986b). It was demonstrated that all inclusion levels had no negative effects on DMI; however, the 10% level was the best inclusion level as it improved growth rate and feed conversion ratio (Harb 1986b). When moderate inclusion levels (20% and 30%) had no negative effects on growth rate of lambs, the highest inclusion level (40%) depressed both growth rate and feed conversion ratio (Harb 1986b).

Al Jassim et al. (1998) investigated the possibility of replacing half or all of (50% of DM) the barley with acorn (Quercus aegilops and Quercus coccifera) in Awassi lambs limit-fed finishing diets. Although it slightly depressed nutrient digestibilities, the lower level of inclusion (25%) was recommended because it demonstrated growth rate and efficiency similar to the control diet. However, the 50% level was inferior in terms of growth rate and efficiency and drastically depressed nutrient digestibilities (DM, OM, NDF, ADF, crude protein (CP), and energy). Al Jassim et al. (1998) suggested that such depressions might have resulted from anti-nutritional compounds (i.e., tannins, polyphenols, flavonoid).

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Table 2 Summary of studies on alternative energy sources and their effects on Awassi sheep performance Reference

Alternative feedstuff (replaced feedstuff): inclusion levels

Animal type

Effect on DMI

Effect on growth rate

Effect on DM digestibility

Effect on FCRa

Al-Ani et al. 1991

Dried date pulp (barley): 0%, 15%, 30%, 45%

Finishing All: NO

Urea-treated olive cake (barley): 0%, 10%, 20%, 30% Acorn (barley): 0, 25%, 50%

Obeidat et al. 2008 Abdullah and Abddel hafes 2004

Additional notes

15%: ↑(T)b 30%: NO

15%: NO 30%, 45%: ↓

15%: superior 45%: inferior

Finishing NAd (restricted) All: NO

All: linear ↓

All: NO

RL: 20–30%

Finishing NA (restricted)

25%: NO 50% : ↓

All: linear ↓

25%: NO 50%: inferior

RL: 25%

P. juliflora (barley): 0%, 10, 20%

Finishing 10%: NO 20%: ↑ (T)

All: NO

All: NO

All: inferior

RL: 20%

P. juliflora (barley and corn): 0%, 15%, 25%, 35%, 45%

Finishing 15%, 25%: NO 15%, 25%: NO NA 35%, 45%: ↓ 35%, 45%: ↓

All: NO

RL: 25%

RLc: 15%

45%: ↓ Al Jassim et al. 1997

Al Jassim et al. 1998

Awawdeh et al. 2009a Restaurant grease (barley): 0%, 3% Awawdeh et al. 2009b Restaurant grease (barley): 0%, 3% Obeidat et al. 2011a Carob (barley): 0%, 12.5%, 25% Obeidat et al. 2011b Dried poultry litter (barley): 0%, 10%, 20% Harb 1986a

Finishing NO

↑

NO

Superior (T)

Nursing NO ewes Finishing All: NO

NA

NA

NA

All: NO

All: NO

All: NO

RL: up to 25%

Finishing All: NO

All: NO

10%: NO 20%: ↓

All: NO

RL: 10–20%e

Dried tomato pomace (barley): Finishing Exp.1: All: NO Exp.1: Exp.1: 10%, 20%, 30% Exp.2: All: NO 10%: NO 20%, 30%: ↑ Exp.2: 0, 25, 50, 75%

NA

Exp.1:

RL:

All: NO

Exp.1: 20%

Exp.2:

Exp.2:

75%: inferior

Exp.2: 50%

25%: NO >25%: ↓ Harb 1986b

Destoned olive cake (barley): 0%, 10%, 20%, 30%, 40%

Finishing All: NO

Bhattacharya and Harb 1973

Dried citrus pulp (corn): 0%, 20%, 40%, 60%

Yearling

Harb, and Shourafa 1982

NaOH-treated dried poultry litter (barley): 0%, 10%

Finishing NO

10%: ↑ NA 20%, 30%: NO

10%: Superior RL: 10% 20, 30%: NO

40%: ↓

40%: Inferior

20%, 40%: NO NA 60%: ↓ (T) NO

20%, 40%: NO NA 60%: ↓ (T) NA

RL: Up to 40%

NO

NO no effect, (↑) increased, (↓) decreased, All all levels mentioned. All effects of alternative feedstuff inclusion compared to the control diet a

FCR feed conversion ratio

b

(T) tendency, not statistically significant

c

RL recommended inclusion level of alterative feedstuff based on corresponding reference

d

NA not applicable

e

For optimal growth, 10% is RL. For meat quality, 20% is RL

Tomato pomace (TP) is one of the agro-industrial byproduct from processing of tomato paste industry that has been used for a long time as AF in sheep feeding. It can be utilized either as wet, dry, or ensiled forms (Harb 1986a; Denek and Can 2006). Due to high moisture contents, TP quickly spoils that limits its utilization (both duration and amount). Ensiling TP with other conventional dry feedstuffs (i.e., wheat straw and/or grain) provides an alternative method to utilize this AF in feeding ruminants for a longer period of time without running into spoilage issues (Denek and Can 2006). Harb (1986a) conducted two experiments

on finishing Awassi lambs to study the partial or complete replacement of barley with dried TP. Harb (1986a) demonstrated that TP can be successfully included in the diet up to 25% without compromising lambs performance. Actually, the 20% and 30% of TP improved growth rates of lambs. However, higher inclusion levels (50% and 75%) depressed growth rates of lambs. Because the chemical composition of TP, that contains relatively high NDF and ADF contents (Denek and Can 2006), is more comparable to low quality fiber sources (i.e., wheat straw) than energy sources (i.e., barley), it is probably more appropriate to

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include TP in sheep diets by replacing fiber rather than energy sources. Several local leguminous trees and shrubs have been used, besides grazing, for feeding sheep in Jordan. Prosopis juliflora pods (PJP) have been investigated as alternative source of barley (Obeidat et al. 2008; PJP included at 0%, 10%, or 20%) or barely plus corn (Abdullah and Abddel hafes 2004; PJP included at 0%, 15%, 25%, 35%, or 45%) for finishing Awassi sheep. Generally, PJP inclusion up to 25% had no effects on DMI, nutrient (DM, OM, CP, NDF, and ADF) digestibilities, or growth rate of lambs (Abdullah and Abddel hafes 2004; Obeidat et al. 2008), but higher levels (35% and 45% of PJP) depressed intake and growth rate of lambs (Abdullah and Abddel hafes 2004). Regarding growth efficiency (feed conversion ratio), Abdullah and Abddel hafes (2004) reported that linear inclusion of PJP had no effects or tended to improve those ratios. In contrast, Obeidat et al. (2008) demonstrated that lambs fed the control diet were more efficient than those fed diets containing PJP. Thus, it appears that PJP can be safely and economically included in diets for finishing Awassi lambs up to 20–25% without negatively compromising performance. Carob pods (Ceratonia siliqua) are fruits of another leguminous tree that can be used as AF to feed sheep. Just recently, Obeidat et al. (2011a) replaced 25% or 50% of barley in the control diet with carob (included at 12.5% or 25%) in finishing diets for Awassi lambs and observed that lambs fed those diets had similar preference (i.e., DMI), growth rate, and feed conversion ratios to those fed the control diet with no detrimental effects on nutrient (DM, OM, CP, NDF, and ADF) digestibilities (Obeidat et al. 2011a). A novel alterative energy source (spent cooking oil from restaurants and cafeterias or yellow grease) was successfully included in diets for finishing Awassi lambs (Awawdeh et al. 2009a) and nursing Awassi ewes and their suckling lambs (Awawdeh et al. 2009b). Replacing about 22% of barley with just 3% of yellow grease improved growth rate and efficiency of finishing Awassi lambs without negatively impacting nutrient (DM, OM, CP, EE, NDF, and ADF) intake or digestibilities (Awawdeh et al. 2009a). Additionally, no substantial gross and/or histopathological changes in the liver, heart, and kidneys were observed in lambs that consumed restaurant oil (Awawdeh et al. 2009a). In another study, Awawdeh et al. (2009b) demonstrated that replacing part of barley with 3% of yellow grease in diets for nursing (just after lambing) Awassi ewes was a useful strategy to decrease production cost. This strategy had no negative effects on BW change of dams or their dietary intake. Additionally, using yellow grease in diets for nursing ewes did not affect the growth rate of their lambs (Awawdeh et al. 2009b). Recently, inclusion of dried broiler poultry litter at 10% or 20% (by partially replacing barley) in diets for finishing Awassi ewes demonstrated similar lambs performance

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(DMI, growth rate, and feed conversion ratio) to the control diet with lower cost of gain (Obeidat et al. 2011b). However, the higher inclusion level (20%) depressed nutrient (DM, OM, CP, NDF, and ADF) digestibilities. Previously, including dried poultry litter treated with sodium hydroxide in diets (containing OC and brewers grains) for finishing Awassi lambs at 10% by partially replacing barley demonstrated no negative effects on DMI, growth rate, or feed conversion ratio of Awassi lambs (Harb and Shourafa 1982). Alternative protein sources and their effects on sheep performance Studies on alternative protein sources and their effects on Awassi sheep performance are summarized in Table 3. Sesame meal (by-product after oil extraction of sesame seeds) has variable but generally fair contents of protein (24–46%; Omar 2002; Obeidat et al. 2009). Sesame meal successfully replaced half or all of the soybean meal (SBM; 16% DM basis) in diets for finishing Awassi lambs without negatively impacting lambs performance (DMI, growth rate, nutrient digestibility, and feed conversion ratio). When sesame meal contained fairly high contents of crude fat (28%) with moderate protein (24%), its dietary inclusion (at 10% or 20% of DM) improved growth rate of Awassi lambs and feed conversion ratio (Omar 2002). However, due to high energy (i.e., fat) contents of sesame meal it numerically reduced palatability (i.e., DMI) of lambs for those diets that contained sesame meal (Omar 2002). Irshaid et al. (2003) investigated the possibility of using sunflower meal as an alternative protein source in rations for Awassi sheep. Half or all of the SBM (17.4% of DM) and some barley were replaced with sunflower meal (contained about 31% CP of DM) in diets for milking/dry ewes and finishing lambs. No effects on DMI, growth rate, nutrient digestibilities, or feed conversion ratio of lambs were observed with such replacements. In milking and dry period, replacing half or all of the SBM with sunflower meal had no negative effects on DMI or BW change of ewes (Irshaid et al. 2003). Bitter vetch (BV; Vicia ervilia) is a legume crop in the Mediterranean region. Its seeds and hay are utilized in feeding ruminants (Haddad 2006; Abdullah et al. 2010) and poultry (Farran et al. 2005; Sadeghi et al. 2009). Including BV at increasing levels (from 0% to 15%), by replacing part or the entire SBM in diets for finishing Awassi lambs, was previously investigated (Haddad 2006; Abdullah et al. 2010). In both studies, all inclusion levels had no negative effects on DMI, growth rate, or feed conversion ration of lambs. In fact, 10% of BV numerically improved growth rate (Abdullah et al. 2010). As increasing the inclusion level of BV in diets for finishing Awassi lambs was

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Table 3 Summary of studies on alternative protein and mixed sources and their effects on Awassi sheep performance Reference

Alternative feedstuff (replaced feedstuff): inclusion levels

Animal type

Effect on DMI

Effect on growth rate

Effect on DM digestibility

Effect on FCRa

Additional notes

Obeidat et al. 2009

Sesame meal (SBMb): 0%, 8%, 16%

Finishing

8%: ↑ 16%: ↓

8%: ↑ 16%: NO

All: NO

All: NO

RLc: 8%

Omar 2002

Sesame meal (barley and SBM): 0,% 10%, 20% Sunflower meal (barley and SBM): Exp. 1, 3: 0%, 17%, 35%

Finishing

All: ↓ (T)d

All: ↑

All: NO

All: superior

RL: 20%

Exp.1, 3:

Exp.1, 2, 3: All: NO

Exp.1, 3: All: NO Exp.2: NAe

Exp.1, 3: All: NO Exp. 2: NA

Exp.1, 3: All: NO Exp. 2: NA

RL: up to 35%

Irshaid et al. 2003

Finishing Exp.2: Milking/ dry ewes

Exp. 2: 0%, 20%, 37.5% Obeidat and Aloqaily 2010 Muwalla et al. 1995

Sesame hulls (barley and SBM): 0%, 12.5%, 25% Dried poultry litter (Wheat bran, SBM, barley): 0%, 30%

Finishing

All: ↑

All: NO

All: NO

All: NO

RL: 25%

Pregnant and milking ewes

NA

NA

NA

NA

NO on lambing rates, birth weight of lambs

Abdullah et al. 2010

Bitter vetch (soybean meal): 0%, 5%, 10%, 15%

Finishing

All: NO

10%: ↑ (T) Others: NO

All: ↓ (T)

NO

RL: 10%

Haddad 2006

Bitter vetch (SBM): 0%, 8%, 15% Brewers grain (SBM): 0%, 15%

Finishing

All: NO

All: NO

All: NO

All: NO

RL: 15%

Finishing

NO

↓

NA

Inferior

Harb, and Shourafa 1982

↓Weaning weigh of lambs

NO no effect, (↑) increased, (↓) decreased, All all levels mentioned. All effects of alternative feedstuff inclusion compared to the control diet a

FCR feed conversion ratio

b

SBM soybean meal

c

RL recommended inclusion level of alterative feedstuff based on corresponding reference

d

(T) tendency, not statistically significant

e

NA not applicable

economically advantageous and because the 10% of BV tended to improve growth rate of lambs, Abdullah et al. (2010) recommended that BV to be included at 10% as they noted depressions in fiber (i.e., NDF) digestibility at levels above 5%. On the other hand, Haddad (2006) observed no depression in nutrient digestibilities even when all of the SBM was replaced with 15% BV. However, Haddad (2006) noted reduced intake of rumen undegradable protein by lambs with including increasing levels (from 0% to 15%) of BV (Haddad 2006). From the studies of Haddad (2006) and Abdullah et al. (2010), it seems that it is safe to include BV at 10% level by partially replacing SBM in finishing diets for Awassi lambs. Brewers grains which have been used for a long time in diets for ruminants other than sheep can be a potential feedstuff, based on availability, to be used for sheep feeding. Previous work on complete replacement of SBM (15% of DM) with brewers grains in diets (containing OC) for finishing Awassi lambs showed some promising results in terms of growth rate; however, feed conversion ratio was depressed (Harb and Shourafa 1982). Further research in Awassi sheep is needed in this area.

Alternative fiber sources and their effects on sheep performance Studies on alternative fiber sources and their effects on Awassi sheep performance are summarized in Table 4. Rangelands utilized for feeding sheep in the Mediterranean region contains several local plants that are usually used for grazing. Additionally, local desert plants are an important feed source for sheep especially those under extensive systems (Hailat 2005). These plants represent a major forage source especially in long and dry periods (Abu-Zanat and Tabbaa 2006). Saltbush (Atriplex) is one of these desert plants that have been studied in feeding sheep. Browse of saltbush (Atriplex halimus and Atriplex nummularia) replaced half or all of barley hay offered (about 1 kg/head/day) to Awassi ewes in addition to concentrate (less than 1 kg/head/day) in late gestation (last 3 weeks of pregnancy), nursing (for 60 days after lambing), and milking (after weaning their lambs for about 61 days) periods (Abu-Zanat and Tabbaa 2006). Partial or complete replacements improved DMI of ewes with no detrimental effects on milk amount produced after weaning lambs

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Table 4 Summary of studies on alternative fiber sources and their effects on Awassi sheep performance Reference

Alternative feedstuff (replaced feedstuff): inclusion levels

Animal type

Effect on DMI

Effect on growth rate

Effect on Effect on Additional Notes DM FCRa digestibility

Awawdeh (unpublished data)

Sun-dried olive cake or acid-treated olive cake (wheat hay): 0%, 10% Lentil (L) or vetch (V) straw (alfalfa hay; A or wheat straw; W): ad libitum Saltbush (barley hay): 0%,50%, or 100% of offered barley hay Saltbush (Barley hay): 0%, 100% of offered hay Corrugated cardboard treated with urea (wheat straw): 0%, 10, 20% Destoned olive cake treated with urea (wheat straw): 0%, 15% Exp. 1,2: dried banana leaves (DBL), DBL treated with urea, DBL treated with NaOH, DBL treated with urea and NaOH (wheat straw): 0%, 20% Exp.3: Dried banana leaves (wheat straw): 0%, 20%

Finishing

NO

Both ↑

Both: NO

Replacement ewes

A, L > V > W

A, L > V > W

A, L > V > NAc W

Ewes in late gestation, suckling, or milking

All: ↑ in all stages

NO for NA their lambs

NA

Finishing

NO

NO

NA

Superior

Finishing

All: NO

All: NO

NA

All: NO

RL: 20%

Finishing

NO

NO

NA

↓ (T)d

RL: 15%

Yearling

All: NO But NA there were differences

All: NO

NA

Nursing (after parturition)

↑ (T)

NA

NA

Haddad and Husein 2001

Abu-Zanat and Tabbaa 2006 Alazzeh et al. 2009 Abo Omar 2001

Harb and Shourafa 1982 Darwish and Harb 1996

Darwish and Harb 1996

NA

Both: NO

RLb: 10%

RL: 50%

NO on ewe’s BW change NO on birth or weaning weights, and growth rate of their lambs

NO no effect, (↑) increased, (↓) decreased, All all levels mentioned. All effects of alternative feedstuff inclusion compared to the control diet a

FCR feed conversion ratio

b

RL recommended inclusion level of alterative feedstuff based on corresponding reference

c

NA not applicable

d

(T) tendency, not statistically significant

during the milking period. Pregnant ewes that were offered saltbush or saltbush with barley hay as forage source gave birth to lambs of similar weights and weaned their lambs at similar weights to those fed the barley hay as a sole forage source. However, overall BW change of ewes throughout all stages was negative for those offered saltbush only or plus barley hay and positive for those offered barley hay only as a forage source. Abu-Zanat and Tabbaa (2006) recommended that 50%, not 100%, of offered barley hay can be replaced with saltbush to prevent possible negative effects on performance (BW change of ewes) that could result from secondary chemical compounds (i.e., tannins) and/or excessive salt intake (i.e., Na). It has been demonstrated that saltbush can alter the mineral status of finishing Awassi lambs fed saltbush as a sole forage source for a long period (Alazzeh et al. 2009).

Straw and hay are the major agricultural byproducts produced from harvesting grain crops that have been extensively used in feeding ruminants. Wheat straw and hay are the most commonly used forage source in feeding small ruminants in Jordan and other Mediterranean countries. Availability of straw and hay from grain crops other than wheat varies from country-to-country and from year-to-year based on amount of rainfall and extent of human demands of grains. Agricultural byproducts (i.e., straw or hay) from leguminous plants (beans, peas, chickpeas, fava bean, lentil, vetch, etc.) at certain levels can be safely used as fiber source for sheep. Haddad and Husein (2001) compared the nutritive value of lentil and vetch straw with alfalfa hay and wheat straw as a fiber source for replacement Awassi ewe lambs. After consuming their concentrate share (about 0.55 kg/head/day), ewes had

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free access to one of the four fiber sources. Nutritive value (palatability, nutrient digestibility, and weight gain) of lentil straw was close to alfalfa hay and better than vetch or wheat straw. As for vetch straw, the nutritive value was somewhat better than that of wheat straw. Olive cake are usually described as being low quality feedstuff (Awawdeh, unpublished data) due to high contents of ligno-cellulotic materials, low protein (Molina Alcaide and Nefzaoui 1996), low digestibility (Al-Masri and Guenther 1995), with anti-nutritive compounds like tannins (Mangan 1988). However, increasing interests in utilizing these agricultural byproducts encouraged researchers to investigate various opportunities to use such cheap AF in sheep feeding. Although OC successfully replaced conventional energy or protein sources in diets for sheep (Harb 1986b; Aguilera et al. 1992; Al Jassim et al. 1997), its chemical composition is comparable to low quality cereal straws. Thus, Awawdeh (unpublished data) suggested that it would be more appropriate to include OC in ruminant diets by replacing low-quality feedstuffs (i.e., roughages) rather than by replacing energy or protein sources. Awawdeh (unpublished data) replaced half of the 20% wheat hay in the basal diet for finishing Awassi lambs with sun-dried OC and acid-treated sun-dried OC and observed no detrimental effects on palatability of lambs to the experimental diets, nutrient digestibilities, growth rate of lambs, or feed conversion ratio. In fact, partially replacing wheat hay with OC improved the growth rate of lambs. However, further improvements in growth rate were not observed by treating OC with inorganic acid (Awawdeh, unpublished data). Previously, Harb and Shourafa (1982) showed that destoned OC treated with sodium hydroxide successfully replaced all of the wheat straw (15% of DM) in diets for finishing Awassi lambs with no detrimental effects on growth rate or DMI of lambs. In another study, we observed that diets containing OC at 12% supported acceptable performance of finishing Awassi lambs (Awawdeh and Obeidat 2011). Dried banana leaves (untreated, treated with urea and/or sodium hydroxide) were used as a roughage source (replaced wheat straw in ad libitum) for Awassi lambs with acceptable, although lower than control, DMI without affecting DM digestibility (Darwish and Harb 1996). However, the duration of study was short (less than a month) and lambs lost weight in all groups as the roughage sources were the only source of nutrients. Additionally, replacing all of the wheat straw (20% of DM) in the basal diet offered for Awassi ewes immediately after parturition for 18 weeks improved milk yield of ewes without negatively affecting BW change of ewes or birth weight, growth rate, or weaning rate of their lambs (Darwish and Harb 1996). However, further research in Awassi sheep is needed in this area. As discussed in previous “Alternative energy sources and their effects on sheep performance” section, TP (in

Trop Anim Health Prod (2011) 43:1297–1309

fresh, dry, or ensiled form) might be a valuable AF to replace conventional feedstuffs. Bizarre materials have been tested in feeding sheep. Corrugated cardboard (treated with urea), as alternative fiber source, is one of those materials that showed promising results. It profitably replaced wheat straw and included up to 20% in diets for finishing Awassi lambs with no detrimental effects on performance of lamb (Abo Omar 2001). As prices of conventional feedstuffs keep increasing, we might see other strange materials entering diets for ruminants. Mixed sources and their effects on sheep performance Studies on alternative mixed sources and their effects on Awassi sheep performance are summarized in Table 3. Sometimes it is not feasible to classify certain AF under a separate category of our AF classification. Either because the chemical composition of that AF is not distinctive to consider it as protein versus energy source and/or when it is included in the diet, it can replace different conventional feedstuff without drastically affecting nutrient composition of the diet. For example, sesame hulls can be considered as both energy and protein source because they have moderate protein (∼25– 30%) and energy (∼4 MCal/kg of metabolizable energy) contents (Obeidat and Aloqaily 2010). Finishing Awassi lambs had preference (i.e., higher DMI) to diets that contained sesame hulls at 12.5% or 25% by partially replacing SBM and barley (Obeidat and Aloqaily 2010). However, greater DMI did not translate into improved growth rate or feed conversion ratio. Thus, Obeidat and Aloqaily (2010) recommended that it is economically favorable to include sesame hulls up to 25% in finishing diets for Awassi sheep. Dried layer poultry litter (contained about 25% CP of DM) was included at 30% (of DM) in diets for Awassi ewes from mating until weaning of their lambs by replacing about 80% of the 25.5% wheat bran, 78% of the 4.5% soybean meal, and 9% of the 68% barley in the control diet (Muwalla et al. 1995). Inclusion of poultry litter did not impact performance of ewes (i.e., lambing rate and number of weaned lambs) or their reared lambs (i.e., birth weight). However, ewes fed the control diet (without poultry litter) weaned heavier lambs than those fed the experimental diet due to numeric increase in their milk production. As discussed in previous “Alternative energy sources and their effects on sheep performance” section, we recently evaluated the effect of partially replacing barley with dried broiler poultry litter on performance of finishing Awassi lambs (Obeidat et al. 2011b). Potential future alternative sources Based on local availability in each country, AF other than those mentioned in previous sections that have been

Trop Anim Health Prod (2011) 43:1297–1309

successfully used in sheep breeds other than Awassi (i.e., Naeemi, Barbarine, Merion, Malpura, etc.) can also be available to feed Awassi sheep. However, such uses and their effects on sheep performance should be investigated in Awassi breed. We will mention some of these AF and briefly present their effects on sheep performance. Byproducts remained after extraction of juices from citrus fruits is one of those potential AF. The byproducts can be utilized as fresh, ensilaged, or dried forms. They have good contents of readily fermentable carbohydrates, but low protein contents. Caparra et al. (2007) demonstrated that solar-dried citrus pulp can be included up to 30% in concentrate mixture, by replacing cereal grains, without affecting the performance of finishing Merino lambs or quality of meat obtained from these lambs. A while ago, Bhattacharya and Harb (1973) demonstrated in a metabolism study that including dried citrus pulp (up to 40% in the diet) by partially replacing corn in diets for Awassi lambs had no effects on DM digestibility and could improve ether extract and fiber digestibility. However, complete replacement of corn with citrus pulp depressed both DM and energy digestibilities (Bhattacharya and Harb 1973). Spineless cactus (Opuntia ficus indica f. inermis) has been shown to be a possible alternative energy source for Barbarine sheep (Ben Salem et al. 2004; Abidi et al. 2009; Rekik et al. 2010). White sweet lupin seeds (Lupinus albus L.) have been shown to be a good protein source that could successfully replace the most commonly used protein source (i.e., soybean) in diets for milking Sarda ewes (Masucci et al. 2006) and finishing lambs (Kung et al. 1991). Grape pomace (Baumgärtel et al. 2007) and grape leaves (Gurbuz 2007) might be a potential fiber source. In arid and semi-arid areas where water salinity is high and/or water is scarce (i.e., desert), salt-tolerant plants (i.e., halophytic plants) might be a good alternative for conventional forages. However, such approach needs intensive and long-term investigation as those done by Al-Shorepy et al. (2010) in the Arabian Gulf region. Additionally, safflower pasture (native in Mediterranean area and resistant to saline and moisture stress) might serve as a forage source in replacement of barley pasture (Landau et al. 2005).

Alternative feedstuffs and their effects on carcass characteristics and meat quality of lambs and milk yield and composition of ewes Not all of the studies discussed in previous sections investigated the effect of AF inclusion on product (meat or milk) characteristics of Awassi sheep. This section reviews the studies in using AF in feeding Awassi sheep that included effects on carcass characteristics and meat

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quality from finishing lambs (Table 5) and milk yield and composition (total solid, protein, and fat contents) from ewes (Table 6) as response criteria. In each study on lambs, carcass characteristics include all or some of the following linear (carcass length, LB; leg length, T; width behind shoulder, Wth; maximum shoulder width, Wf; gigot width, G; tissue depth, GR; eye muscle width, A; eye muscle depth, B, and eye muscle area) and fat (leg fat depth, L3; shoulder fat depth, S2; fat depth, C; rib fat depth, J; fat thickness, L3; fat tail weight, and mesenteric fat weight) measurements. Effect of AF inclusion on meat composition (lean, fat, and bone percentages) and quality (ultimate pH, cooking loss, water-holding capacity, shear force, and color coordinates: brightness; L*, redness; a*, yellowness; b*) were investigated some of these studies. Dietary inclusion of PJP at 10% had no effects on carcass weight, dressing percentage, all carcass linear and fat dimensions, loin muscle composition, or meat quality (Obeidat et al. 2008). However, the 20% inclusion of PJP increased shoulder and gigot width and eye muscle areas and decreased water-holding capacity (Obeidat et al. 2008). Similarly, PJP inclusion at 15% or 25% had no effects on carcass weight, dressing percentage, or measured carcass characteristics except for increased fat tail weight (Abdullah and Abddel hafes 2004). However, higher inclusions of PJP (35% and 45%) decreased carcass weight and dressing percentage (Abdullah and Abddel hafes 2004). Effects of dietary inclusion of sesame industry byproducts (meal or hulls) on carcass yield, characteristics, and quality have been investigated in Awassi lambs. Although partially replacing barley and SBM with 8% or 16% sesame meal had no effects on carcass weight, carcass linear and fat measurements, leg and loin composition, or meat quality data, such replacements depressed dressing percentage due to heavier noncarcass components (Obeidat et al. 2009). It has been shown that partial or complete replacement of SBM with 12.5% or 25% of sesame hulls did not affect carcass weight, dressing percentage, most of carcass linear and fat measurements, most of leg and loin composition, and most of meat quality parameters (Obeidat and Aloqaily 2010). However, both levels increased eye muscle depth, mesenteric, and kidney fat weights, but, only the 12.5% level increased meat whiteness (Obeidat and Aloqaily 2010). No effects on carcass weights, dressing percentages, or carcass linear and fat dimensions were observed when BV was included in diets for finishing Awassi lambs at 5% or 10% (Abdullah et al. 2010). However, lean percentage in leg was increased with the above inclusions. Additionally, Abdullah et al. (2010) demonstrated that fat depth of carcass, leg fat depth, and total fat contents of the leg tended to increase with the highest inclusion level (i.e., 15%) without affecting carcass weight, dressing percentage,

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Table 5 Summary of studies in effects of alternative feedstuffs on carcass characteristics and meat quality of finishing Awassi lambs Reference

Alternative feedstuff (replaced feedstuff): inclusion levels

Effects on carcass weight

Effects on dressing %

Effects on carcass characteristicsa

Effects on meat compositionb

Effect on meat qualityc

Obeidat et al. 2008

P. juliflora (barley): 0%, 10%, 20%

All: NO

All: NO

10%: NO

All: NO

10%: NO

Abdullah and Abddel hafes 2004 Awawdeh et al. 2009a Obeidat et al. 2011a Obeidat et al. 2011b

P. juliflora (barley and corn): 0%, 15%, 25%, 35%, 45% Restaurant grease (barley): 0%, 3% Carob (barley):0%, 12.5%, 25% Dried poultry litter (barley): 0%, 10%, 20%

15%, 25%: NO 35%, 45%: ↓

15%, 25%: NO 35%, 45%: ↓

20%: only ↑shoulder and Gigot width and eye muscle are All: NO 15%: ↑fat tail weight

↑

NO

All: NO All: NO

Abdullah et al. 2010

Bitter vetch (soybean meal): 0%, 5%, 10%, 15%

All: NO

Sesame meal (soybean meal): 0%, 8%, 16% Sesame hulls (barley and soybean meal): 0%, 12.5%, 25% Destoned olive cake treated with urea (wheat straw): 0%, 15%

Obeidat et al. 2009 Obeidat and Aloqaily 2010 Harb and Shourafa 1982

20%: only ↓water holding capacity NA

NA

NO

NO

All: NO

Only ↑tissue and rib fat depths All: NO

All: NO

All: NO

All: NO

10%: NO

10%: NO

10%: NO

20%: ↓rib fat depth and mesenteric fat

20%: ↓total fat

20%: only ↑whiteness and ↓redness

All: NO

5%, 10%; NO

NA

All: NO

All: ↓

15%: only tended to ↑ fat depth All: NO

5%, 10%: only ↑lean% 15%: NO All: ↑loin lean%

All: NO

All: NO

All: NO

Both: only ↑eye muscle depth

All: only ↑mesenteric and kidney fat

12.5%: only ↑whiteness

NO

NA

NA

NA

NA

NO no effect, (↑) increased, (↓) decreased, All all levels mentioned. All effects of alternative feedstuff inclusion compared to the control diet a

Include some or all of the following linear (LB carcass length, T leg length, Wth width behind shoulder, Wf maximum shoulder width, G gigot width, GR tissue depth, A eye muscle width, B eye muscle depth, eye muscle area) and fat (L3 leg fat depth, S2 shoulder fat depth, C fat depth, J rib fat depth, L3 fat thickness, fat tail weight, mesenteric fat weight) measurements c

Of dissected leg, loin, or other part of the carcass and include lean, bone, and fat percentages

d

Include ultimate pH, cooking loss, water holding capacity, shear force, and color coordinates (brightness; L*, redness; a*, yellowness; b*)

or leg composition. Recently, dietary inclusion of another alternative energy source (i.e., carob included at 12.5% or 25%) did not affect carcass weights, dressing percentages, carcass linear and fat measurements, leg and loin composition, or meat quality data in Awassi lambs(Obeidat et al. 2011a). Waste restaurant oil (yellow grease) has been investigated as alternative energy source for Awassi milking ewes

and finishing lambs. Including yellow grease at 3% improved carcass weights without affecting dressing percentage, leg and loin composition, meat quality parameters, all carcass linear and fat measurements except for increased tissue and rib fat depth (Awawdeh et al. 2009a). Additionally, dietary inclusion of 3% of yellow grease was a useful strategy to decrease production cost without affecting milk

Table 6 Summary of studies in effects of alternative feedstuffs on milk yield and composition Awassi ewes Effects on milk yield

Effects on milk compositiona

Reference

Alternative feedstuff (replaced feedstuff): inclusion levels

Awawdeh et al. 2009b

Restaurant grease (barley): 0%, 3%

NO

NO

Irshaid et al. 2003

Sunflower meal (barley and soybean meal): 0%, 20%, 37.5%

NO

NO

Muwalla et al. 1995

Dried poultry litter (wheat bran, soybean meal, barley): 0%, 30%

Numeric ↓

NA

Abu-Zanat and Tabbaa 2006

Saltbush (barley hay): 0%, 50%, or 100% of offered barley hay

NO

NA

Darwish and Harb 1996

Exp.3: dried banana leaves (wheat straw): 0%, 20%

↑

NO

NO no effect, (↑) increased, (↓) decreased, All all levels mentioned. All effects of alternative feedstuff inclusion compared to the control diet a

Includes total solids, protein, or fat %

Trop Anim Health Prod (2011) 43:1297–1309

yield, milk composition, or composition yield of ewes (Awawdeh et al. 2009b). At moderate inclusion (10% of DM), dried poultry litter did not affect carcass weight, dressing percentage, carcass linear and fat measurements, leg and loin composition, or meat quality data obtained from Awassi lambs (Obeidat et al. 2011b). But higher levels (20%) produced lighter meat and enhanced meat quality of carcasses (greater lean to fat ration) as a reflect to lower subcutaneous and total fat percentages, lower contents of mesenteric fat, and lower rib fat depth (Obeidat et al. 2011b). On the other hand, it has been shown that dietary inclusion of dried poultry litter to Awassi ewes could depress milk yield due to potential decrease in dietary contents of metabolizable energy (Muwalla et al. 1995). Effects of using other AF on milk yield and composition have also been investigated. For example, replacing all of the wheat straw (20% of DM) with dried banana leaves in diets offered to Awassi ewes immediately after parturition for 18 weeks improved their milk yield without negatively affecting milk composition (Darwish and Harb 1996). Additionally, partial or complete replacements of offered barley hay with browse of saltbush had no effects on milk amount produced by Awassi ewes after weaning their lambs (Abu-Zanat and Tabbaa 2006). By replacing SBM, inclusion of sunflower meal up to 37.5% did not negatively affect milk yield or composition of Awassi ewes (Irshaid et al. 2003).

Constraints and limitations Several factors limit the efficient utilization of AF in sheep feeding. These factors vary from country to another depending on local sets of production systems, availability of resources, and economic factors. These factors can be summarized by the following points and should be considered in dietary inclusion of a particular AF: 1. Availability (amount, duration, and price) of AF. 2. Variability in chemical composition and nutritive value of AF. 3. Storage and transport of AF. 4. Presence of anti-nutritive compounds and/or compounds of low palatability and digestibility in AF that might need further processing to overcome this issue. 5. Composition of the basal diet in which AF is to be included. 6. Physiological and production stages (finishing, milking, maintenance, etc.) of sheep to which AF is to be used. 7. Desired production (meat or milk) level and quality of sheep to which AF is to be fed.

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Conclusions, recommendations, and future research At this point, it is apparent that some AF can be safely included in diets for Awassi sheep at different production stages to lower the production cost without negatively affecting animal performance. With appropriate inclusion, AF can be included in diets for Awassi sheep without negatively impacting the quantity or quality of products (meat or milk). Knowing the nutritive value of a particular AF and taking in consideration the animal and feed factors discussed earlier in this review guarantee a successful utilization of AF. Response criteria (i.e., animal acceptance to the diet, nutrient digestibility, growth rate, cost of gain, meat quality, milk amount, and milk composition, etc.) must be clearly defined when setting up the appropriate inclusion levels for a given AF. However, inappropriate dietary inclusion of AF might dramatically affect sheep performance and could modify the composition and quality of sheep product. Future research should focus on means (feed additives, physical, and/or chemical methods) for improving the nutritive value and optimizing the inclusion level of AF without compromising product quality and animal health. Effects of AF inclusion on ruminal ecosystem and parameters should be considered in AF evaluation. Continuous search and investigation of new AF should be encouraged.

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