Incorporation of cactus (Opuntia ficus-indica f. inermis) in young goats diets: 1. Effects on intake, digestion, growth and carcass composition

N Atti*, M Mahouachi*, F Zouaghi and H Rouissi**

INRA-Tunisie, Laboratoire de Productions Animales et Fourragères, 2049 Ariana, Tunisia
* Ecole Supérieure d’Agriculture du Kef, Le Kef, Tunisia
** Ecole Supérieure d’Agriculture de Mateur, Mateur, Tunisia
belhaj.naziha@iresa.agrinet.tn

Abstract

The objective of this study was to determine the effects of cactus incorporation on digestibility, daily gain and carcass characteristics of growing goat kids. Thirty male kids (initial live weight (LW) =17.4 ± 0.9 kg) were assigned randomly to five dietary treatments. All groups received 600 g of oats hay per animal per day. The two first groups received 600 and 400 g of concentrate containing 130 (C130) and 200 (C200) g crude protein (CP) per kg of dry matter (C130 and C200 groups, respectively). Two other groups received spineless cactus (Opuntia ficus indica f. inermis) ad libitum and 400g of C130 (C130-Cac) and 300 g of C200 (C200-Cac). The last group received spineless cactus ad libitum and 200 g soya bean meal (soya-cac).

Total dry matter (DM) intake was greater for the cactus diets (1371, 1317 and 1306 g/d DM for C130-Cac, C200-Cac and Soya-Cac groups, respectively) than for the others (1060 and 871 g/d DM for C130 and C200 groups). The inclusion of cactus in the regimens resulted in a decrease (P<0.05) in the water consumption, moreover when the daily intake of cactus increased from 501 to 605 g, water consumption became almost nil (0.76 to 0.15 kg/day). After 12 weeks of the experimentation period, LW was similar for all groups. The average daily gain ranged between 30 and 61g/d; cactus intake tended to increase the growth rate without significant difference between groups.

DM and organic matter (OM) digestibilities were significantly (P < 0.05) higher for the C130, C130-Cac, C200-Cac and Soya-Cac groups than for the C200 group, it is 0.82 vs 0.73 for DM and 0.84 vs 0.74 for OM; the 0.82 and 0.84 values were the averages of the first four groups. The digestibility of crude fiber was significantly higher (P<0.001) for kids fed cactus diet compared with kids fed the concentrate diet. Apparent CP digestibility averaged from 0.72 to 0.80, but no significant (P > 0.05) differences were observed between treatments.

Empty body weight, carcass weight, dressing percentage and non-carcass compounds were comparable among kids receiving the five diets. However, kids given cactus diet had relatively more muscle (P < 0.001) and less fat (P < 0.001) than those fed concentrate diets. The proportion of carcass bone was similar for all diets.

Keywords: Carcass characteristics, digestibility, goat kids; growth; spineless cactus

Introduction

The consumption of goat meat increases particularity in the summer season, as it could become an ideal choice for health conscious consumers since goats being a much leaner animal, and present a good source of desirable fatty acids and deposit higher amounts of polyunsaturated fatty acids than other ruminants (Banskalieva et al 2000). Furthermore, goats are better adapted than sheep to extensive conditions and to harsh environments (Erasmus 2000). Arid and semi-arid areas are characterized by limited resources, herbaceous and rare green forage production particularly during hot season (summer), so animals are heavily supplemented with concentrate (Nefzaoui and Ben Salem 2002; Atti et al 2006). In this region, the spineless cactus (Opuntia ficus indica f. inermis), which is worthwhile for soil conservation and runoff reduction, is widely cultivated and could be considered as green forage available in all seasons. It is characterized by a high palatability, digestibility, a high content of water, soluble carbohydrates, ash, Ca and K and vitamin A (Nefzaoui and Ben Salem 2003). However, ration digestibility and lambs or goats growth on cactus were studied only when cactus was fed with low quality feedstuffs like straw (Nefzaoui and Ben Salem 2003) or with a very low amount of hay (Atti et al 2006). The objective of this study was to determine the effect of cactus inclusion in an oat hay/concentrate diet on growth performance, nutrient digestibility, and slaughtering characteristics of growing male goat kids. The effects on meat characteristics and fatty acid composition were reported in the companion paper (Zouagui et al).

Material and methods           

Experimental feeds

Spineless cactus (Opuntia ficus-indica f. inermis): cladodes used in this experiment included that of one and two-year-old, they were harvested and cached daily. This vegetal material provided from a ten-year-old plantation in the farm of the National Institute of Agricultural Research of Tunisia (INRAT) in Ouesslatia, semi-arid region (mean annual rainfall 370 mm). Concentrates, used as supplements, were a mixture of processed barley grain and soya bean meal or soya bean meal alone (Table1).

One concentrate (C130) was formulated to contain 130 g crude protein (CP) per kg of dry matter; this CP proportion is optimum for growing goats (Tegene Negesse et al 2001; Atti et al 2004). The second concentrate contains 200 g CP/kg DM; the third concentrate was limited to soya bean meal (Soya). The distribution of concentrates at 600, 400 and 200 g/day/head for C130, C200 and Soya, respectively, provided the same quantity of CP; the use of C200 and Soya concentrates permits an economy of concentrate cost. The unit cost of these concentrates was 0.35, 0.43 and 0.70 TD (Tunisian Dinar), respectively.

Growth trial

The experiment started in middle July with a total of 30 male kids 7 months old and 17.4 kg body weight (BW). The mean ambient temperature during the experimental period was 35°C, with average values of 25 at morning (07.00h) and 40 at 16.00h. Animals were divided into 5 groups assigned to five treatments. All groups had free access to water and were offered per animal per day 600 g of oat hay which equivalent to 3.4 % of BW. The two first groups received 600 and 400 g of C130 and C200 and were considered C130 and C200 groups, respectively. The concentrate distribution was reduced for other groups, which were offered spineless fresh cactus ad libitum, to 400 g of C130, 300 g of C200 and 200 g of soya for C130-Cac, C200-Cac and soya-cac groups, respectively. Feed intake was recorded daily per group and goat BW every 15 days throughout the feeding period. Animals were allowed 84 days in this growth trial and then were slaughtered.

Digestibility trial

A total collection digestibility trial was carried out using 15 other kids divided into 5 groups assigned to the five treatments of growth trial. We used 3 animals per treatment because we were in shortage of animals in the same category. The digestibility trial consisted in 7 days of adaptation and a subsequent 7 days for faeces collection period. During the digestibility measurement, each feed of rations was taken every day and bulked separately. For animals receiving cactus, they finished concentrate intake and then received cactus. Animals were housed individually in metabolic cages. They had free access to water and were fed once a day at 8:30, the following day each feed refusal was collected weighed, sampled, and then stored separately. Total daily faecal output for each animal was also collected, weighed and homogenised. Two samples were taken; one of 100 g was used to measure faecal DM. The second of 30 g was kept at -15 °C, and then samples of the seven days of faeces collection period were pooled in a one for each animal for later chemical analysis. Also, daily water consumption was recorded during the digestibility trial.

Chemical analyses 

Samples of cactus, hay, concentrates and portions of individual pooled samples of refusals and faeces were dried (50 °C), ground (1-mm screen), and stored for subsequent analyses. DM was determined by drying at 105 °C for cactus, hay, concentrates (food and refusal) and at 80 °C for faeces until constant weight. Mineral content was then determined by ashing at 600 °C for 8 h. Nitrogen was determined by Kjeldahl method (CP = N x 6.25) and ash-free neutral detergent fiber (NDFom) according to Van Soest et al (1991).           

Animal slaughtering and carcass dissection 

At slaughter, kids BW were recorded, blood was collected and weighed, bodies were skinned and the head and feet were removed. The carcass was eviscerated and all red organs (liver, kidneys, spleen, and heart), omental and mesenteric fat (OMF) were weighed. All fractions of the digestive tract (reticulo-rumen+omasum (rumen), abomasum, and intestine) were weighed full then empty after hand rinsing, in order to determine the weight of digestive contents. Carcasses were weighed warm (WCW) and cold (CCW) after storage 24 h at 4°C. After removing the tail, each carcass was split longitudinally into two halves; the left sides were separated into five joints (Colomer-Rocher et al 1987). Every joint was weighed and dissected into fat (subcutaneous, intermuscular, renal and pelvic), muscles and bones. Other tissues such as tendons, lymph and nodes were separated as waste. Total body fat (TBF) was computed as the sum of carcass fat and OMF. 

Calculation and statistical analysis 

Empty body weight (EBW) was calculated as the difference between BW before slaughter and weight of digestive contents. Commercial and real dressing percentage (CDP, RDP) were calculated according to the following equations:

CDP (%) = 100 * WCW / BW

RDP (%) = 100 * CCW / EBW

Statistical analysis was performed by analysis of variance using the GLM procedure of SAS (1989). Data were first analyzed using the initial weight as a covariate but there was no difference, so only the fixed effect of dietary treatment was included. Differences between groups were evaluated by t-test; significance was declared at p<0.05. The contrast [C130+C200] vs [C130-Cac+C200-Cac+Soya-Cac] was used to show the global effect of inclusion of cactus. The statistical effects of dietary treatment on digestibility, growth, and body composition were studied, but not intake data because animals were group housed and fed.

Results   

Food and water intake 

The chemical composition of cactus and the three concentrates was shown in Table 1. The different concentrates distributed were entirely consumed and hay intake, which was similar for all kid groups, averaged 500 g DM per day. However, cactus intake was higher for kids offered Soya-Cac diet than for kids of C130-Cac and C260-Cac diets (Figure 1).

In the beginning of experiment, cactus intake was very low for the three groups (232 g DM/day in average), then cactus consumption increased progressively until week 8 and became constant (Figure1). At this moment, the intake reached 558, 559 and 666 g of DM per day for C130-Cac, C200-Cac and Soya-Cac groups, respectively. Hence, total DM intake of kids on cactus regimens was higher than other groups (Table 2).

Also, the average CP intake was higher for animals on cactus regimens; it increased from 105 g/kg DM for C130 group to 157 g/kg DM for Soya-Cac group.

Water intake was significantly affected (P<0.001) by diet treatments and the contrast [no cactus vs cactus] was significant. The inclusion of cactus in the regimens leads to decrease the water consumption (Table 2). The average daily water amount drank was 0.42 kg in cactus regimen vs 1.4 for the other ones. Furthermore and intra cactus groups, the water intake decreased when cactus intake increased. When the daily intake of cactus increased from 501 to 605 g, water intake decreased from 0.76 to 0.15 kg/day, it is almost nil. In fact, water intake was significantly and negatively correlated to cactus intake (r = - 0.91, P<0.001). 

Digestibility            

Results on DM, OM, CP and CF digestibility of experimental diets were given in Table 3.

The DM and OM digestibilities were significantly affected (P <0.05) by diet treatment, and the contrast was significant (P<0.001). Both parameters ranged from low values of 0.73 and 0.74 for C200 group to high ones of 0.82 and 0.84 for Soya-Cac, respectively. Within cactus groups, there was no significant difference (Table 3). The improvement of digestibility with cactus introduction was more clear (P<0.001) when the CF was considered (table 3). The increase of CF digestibility reached 0.20 in Soya-Cac group; while CP digestibility was not affected by the diet treatment; it was similar (P > 0.05) for all diet treatments and averaged 0.75. 

Kid's growth  

Initial BW was similar among groups, it ranged between 16.8 and 18.3 kg. Average daily gain tend to be higher for cactus kids than no cactus ones (50 vs 34 g respectively), but no significant differences were observed among groups (Table 2). So, after the experimentation period (Figure 2), the kids attained similar final BW which varied from 21.1 to 22.2 kg. 

Carcass weight and dressing percentages

Mean values of EBW, carcass weight and non-carcass component of the kids by five diets were shown in Table 4.

There were no significant differences in EBW and carcass weights between the five regimes. Also, dressing percentages were not affected by the diet treatments, the mean CDP was 43.9 % and the mean RDP was 53.2 %. External (skin, head and feet) and red organ weights were comparable among goats receiving different diets. Similarly, there were no significant differences between groups for the digestive tract and their content.  

Carcass composition 

Carcass joints

The proportions of cuts (g/kg half-carcass) in the carcass were mentioned in Table 5, the proportions of the main anatomical cuts, the leg, the shoulder and the rack, in whole carcass averaged 325, 225 and 262 g/kg, respectively.

There were no significant differences between the five groups (P >0.05), in addition the contrast [no cactus vs cactus] was not significant.

Carcass tissues  

The results for weight (g) and proportions of different tissues in whole carcasses and weight of different fat depots were presented in Table 5. The muscle weight ranged between 5091 and 5704g without significant difference between groups. Also, bone weight was comparable among animals receiving the five diets. On the contrary, there were significant diet effects on fat weight (P<0.001), kids given cactus diet had less fat than those fed no cactus. As proportions of carcass weight, there were significant effects (p<0.001) of diet on muscle and fat values, carcasses of kids given cactus diet presented relatively less fat (105 g/kg) and more muscle (62 g/kg) than those fed no cactus diet (135 g/kg fat and 58 g/kg muscle). But, the proportion of carcass bone was similar for all diets (26 g/kg).

Within fat depots, kids fed cactus diet deposited less subcutaneous and inter-muscular fat (P<0.001) compared to those fed the concentrate based diet. Pelvic and kidney fat weights were in the range of 36–81 g and 82–149 g, respectively. No significant difference (P>0.05) was found for omental and mesenteric fat weights among the five groups. Indeed, TBF was significantly affected by diet treatment (P<0.05) and the contrast [no cactus vs cactus] was highly significant (P<0.001), the groups fed cactus had the lowest total body fat. The total body fat decreased when the substitution of concentrate with cactus in kid’s diet increased, animals given Soya-Cac diet had relatively less total body fat (1340g) than those fed C130-Cac (1454 g) and C200-Cac (1384 g) diets. As proportions of EBW, TBF was lower (P<0.01) for cactus animals than other groups (table 5).

Discussion 

Feed nutritive characteristics and intake 

The two concentrates (C130 and C200) were formulated to contain 130 and 200 g CP/kg DM. Atti et al (2004) suggest that the optimum diet crude protein level for growing goat is approximately 110 g/kg DM and that any increase above this level seems without effect on meat production efficiency. The no cactus diets brought 100 and 118 g CP/kg respectively which is similar to the level proposed by Atti et al (2004). Chemical composition of cactus in this study showed less crude fiber (128 g/kg DM) and higher CP level (84 g/kg DM) than those obtained in other studies (Nefzaoui and Ben Salem 2002; Atti et al 2006); these differences can be attributed to the age of cladodes used in both experiments. So, CP intake in cactus was not negligible and total CP intake was higher for the three cactus groups then the two other ones.

The hay consumption was similar for all groups. In fact, there was nor substitution neither stimulation of hay intake by cactus. While on straw, cactus incorporation stimulated significantly the wheat straw intake (Nefzaoui and Ben Salem 2003). In reverse, the reduction of concentrate distribution in the group Soya-Cac was compensated by cactus intake, which was higher for Soya-Cac group compared with the two other cactus groups consuming more concentrate.             However, it must keep in mind that the hay was distributed in fixed quantity. Furthermore, cactus inclusion increased total DMI by 37 % (C200 vs C130-Cac), this result was similar to what Tegegne et al (2005) found in sheep (39 %). Moreover, the increase in feed intake for the three cactus groups (C130-Cac, C200-Cac and Soya-Cac) was associated with the high protein and energy intake by kids.  

Water consumption 

Feeding cactus decreased the volume of water consumed by kids from 1.4 liters for the no cactus diet to 0.15 liters for Soya-Cac one. Furthermore, when the level of cactus consumption increased water consumption decreased, this is in accordance with other results (Ben Salem et al 1996). The reduction of water intake by animals should be considered as the most important aspect of Opuntia in dry areas; this aspect would resolute the problem of animal watering in these areas given the water rarity and the dispersion of watering points, animals expend a lot of energy to reach them.  

Digestibility 

The inclusion of cactus in the diet had a positive effect on DM, OM, CP and crude fiber digestibility of the diet. As we suggested previously, the higher digestibility of cactus regimens could account for the higher DM and protein intake. These values were higher than those obtained by Nefzaoui and Ben Salem (2003) with sheep fed with wheat straw and cactus. Higher crude fiber digestibility on cactus compared to no cactus diet may also be due to the lower content of fiber, especially the lignocellulose fraction and higher hemicellulose (Nefzaoui and Ben Salem 2003). The high levels of lignocellulose or lignin are liable for low digestibility of feedstuffs, but the high levels of hemicellulose are easily digestible, for than, the digestibility of cactus could be awaited to be higher. The lower values of the DM, OM and crude fiber digestibility for C200 group compared to the other groups was probably associated with the reduction of the concentrate intake for this group than C130 groups. Chandramoni et al (2000) and Hadded (2005) found increased digestibility of DM, OM and CP with increasing the concentrate portion of the diets for sheep and kids. 

Kid's growth 

During the fattening period, the addition of cactus and reduction of concentrate tend to improve the ADG from 34 g/day (C130) to 55 g/day (C200-Cac), this result is in relationship with the high energy and protein intake of groups fed cactus diets, which characterized by a high DM intake and digestibility. These results confirmed partially those of Negesse et al (2001) and Titi et al (2000) who observed a linear increase in weight gain for Saanen kids and Black goat kids, fed with higher levels of diet CP. These results showed clearly that cactus, which is largely used in arid and semi arid areas for rangeland rehabilitation, is also a potential cost-effective fodder for weaned kids in semi-arid areas. However, other researches remain still necessary to determine the optimal conditions of its incorporation in goat diet. However, the unchanged growth rates among treatments would suggest that the nutritive value of diets was not the only limiting factor but reflects also the low potential growth rate of this local breed. 

Non-carcass components       

Goat kids had the same slaughter BW, so the EBW and carcass weight were not affected across diet because these parameters depended on slaughtering BW (Colomer et Espejo 1972; Marinova et al 2001; Atti et al 2003). In addition, weights of all organs were not affected by the diet treatment despite the increase of the crude protein and energy in the cactus regimens. However, on classic regimens (hay + concentrate) liver and gut goat kids weights varied according to protein level (Atti et al 2004).  

Carcass composition 

As proportions of carcass, joints had similar values on all diets; this result on constancy of joint proportions in the carcass concord with the anatomical harmony established by Boccard and Dumont (1960) and confirmed by several authors (Sents et al 1982; Atti et al 2006). Body muscle and bone weights were similar for all diets but fat weight was lower for cactus groups than control ones. However, all animals had the same bone but different fat and muscle proportions. Bone is a tissue with early development in all-animal species and does not depend on regimen at older ages (Kamalzadeh et al 1998; Atti et al 2006). The constancy of muscle weight was in relationship with the lack of treatment effects on slaughter BW and hence carcass weight. It is known that muscle weight is strongly correlated to carcass weight (Kemp et al 1976; Sents et al 1982; Atti and Khaldi 1988).  However, it is necessary to point out that cactus supply decreased the fat tissue weight and proportion and increased muscle proportion in the carcass suggesting that carcasses of fed cactus goats were leaner than carcasses produced on grain diets, which confirmed our anterior results (Atti et al 2006) concerning carcass adiposity reduction by cactus intake. Hence, cactus act on carcass composition as a green forage confirming other results where animals (Steers, beef and lambs) raised on pasture displayed a greater proportion of muscle and a lower percentage of fat compared to concentrate fed animals (Mandell et al 1998; Atti and Abdouli 2001; Nuerberg et al 2005). The incorporation of cactus in the three groups “C130-Cac, C200-Cac, Soya-Cac” tended to decrease the proportion of subcutaneous and intermuscular adipose tissues from 450 and 340 g/kg compared to the control groups. Similar results were reported by Diaz et al (2002) and Caneque et al (2003) on lambs fattened at pasture which had lower percentages of subcutaneous and intermuscular fat than the dry lot lambs. However, it is worth to note that internal fat depots were similar compared to the increased deposition of subcutaneous and intermuscular adipose tissues in no cactus groups.

Conclusions 

• The results of this study showed that cactus may constitute a potential effective fodder for weaned kids in semi arid areas.

  
  

• Reducing concentrates level, with or without cactus did not affect goat kid’s performance; moreover, cactus can be used to reduce the concentrate feeds, feeding cost and, hence increase farmer’s income.

  
  

• The cost of offered concentrate per animal per day was 0.21, 0.17 and 0.14 TD for C130, C200 and cactus groups, respectively. So raising kids under cactus regimen could be more economic than the classic regimen with great amounts of concentrate (600 g). Indeed, total DM intake, digestibility and growth rate of kids were improved by introduction of cactus in comparison of conventional diet (hay and concentrate). Therefore, the high water content of cactus helps to resolve the problem of watering animals, the cactus allow to reduce considerably the volume of water consumed by kids during the summer seasons to 90 %. Finally, the carcasses of kids fed cactus were leaner trying to attract by the nutritionists.

Acknowledgements

The authors gratefully acknowledge the technical assistance of B Chourabi and general Ouesslatia farm staff in the conduct of this study, and Dr Soufia with her team from Beja slaughtering house for their assistance.

References 

AOAC 1999 Official Methods of Analysis of the Association of Officiel Analytical Chemists. 16^th edition., 15^th revision. AOAC International, Gaithersburg, MD, USA.

Atti N et Khaldi G 1988 Composition de la carcasse et qualité de la viande d'agneaux de races Barbarine et Noire de Thibar en fonction du poids à l'abattage. Annales INRAT Volume 61, fascicule11.

Atti N et Abdouli H 2001 Effets du niveau du concentré sur les performances bouchères des agneaux de race Barbarine conduits au pâturage ou en bergerie. Annales INRAT 73: 151-163

Atti N, Ben Salem H and Priolo A 2003 Effects of polyethylene glycol in concentrate or feed blocks on carcass composition and offal weight of Barbarine lambs fed Acacia cyanophylla Lindl. Foliage. Animal Research 52: 363-375 http://animres.edpsciences.org/index.php?option=article&access=standard&Itemid=129&url=/articles/animres/pdf/2003/04/Z3408.pdf

Atti N, Rouissi H and Mahouachi M 2004 The effect of dietary crude protein level on growth, carcass and meat composition of male goat kids in Tunisia. Small Ruminant Research 54: 89–97

Atti N, Mahouachi M and Rouissi H 2006 The effect of spineless cactus (Opuntia ficus-indica f. inermis) supplementation on growth, carcass, meat quality and fatty acid composition of male goat kids. Meat Science 73: 229-235

Banskalieva V, Sahlub T and Goetsch A L 2000 Fatty acid composition of goat muscles and fat depots: a review Small Ruminant Research 37: 255-268

Ben Salem H, Nefzaoui A, Abdouli H and Orskov E R 1996 Effects of increasing level of spineless cactus (Opuntia ficus-indica var. inermis) on intake and digestion by sheep given straw-based diets. Animal Science 62: 293-299

Boccard R, Buchter L, Casteels E, Cosentino E, Dransfield E, Hood D E, Joseph R L, MacDougall D B, Rhodes D N, Schon I, Tinbergen B J and Touraille C 1981 Procedures for measuring meat quality characteristics in beef priduction experiments. Report of a working group in the Commission of the European Communities (CEC) beef production research programme. Livestock Production Science 8: 385-397

Boccard R et Dumont B L 1960 Etude de la production de la viande chez les ovins. II : Variation de l’importance relative des différentes régions corporelles de l’agneau de boucherie. Annales de Zootechnie 9:  (4): 355-363 http://animres.edpsciences.org/index.php?option=article&access=standard&Itemid=129&url=/articles/animres/pdf/1960/04/Ann.Zootech._0003-424X_1960_9_4_ART0005.pdf

Caneque V, Velasco S, Diaz M T, Huidobro FRD, Pérez C and Lauzurica S 2003 Use of whole barley with a protein supplement to fatten lambs under different management systems and its effect on meat and carcass quality. Animal Research 52: 271–285 http://animres.edpsciences.org/index.php?option=article&access=standard&Itemid=129&url=/articles/animres/pdf/2003/03/Z3306.pdf

Chandramoni Jadhao S B, Tiwari C M and Khan M Y 2000 Energy metabolism with particular reference to methane production in Muzaffarnagari sheep fed rations varying in roughage to concentrate ratio. Animal Feed Science and Technology 83: 287-300

Colomer-Rocher F, Morand-Fehr P and Kirton H 1987 Standard methods and procedures for goat carcass evaluation, jointing and tissue separation. Livestock Production Science 17: 149-159

Diaz M T, Velasco S, Canéque V, Lauzurica S, Ruiz de Huidobro F, Pérez C, Gonzalez J and Manzalez J 2002 Use of concentrate or pasture for fattening lambs and its effect on carcass and meat quality. Small Ruminant Research 43: 257–268

Erasmus J A 2000 Adaptation to various environments and resistance to disease of the improved Boer goat. Small Ruminant Research 36: 179–187

Haddad S G 2005 Effect of dietary forage: concentrate ratio on growth performance and carcass characteristics of growing Baladi kids. Small Ruminant Research 57: 43–49

Kamalzadeh A, Koops W J, Van Bruchem J, Tamminga S and Zwart D 1998 Feed quality restriction and compensatory growth in growing sheep: development of body organs. Small Ruminant Research 29: 71-82

Kemp J D, Johnson A E, Stewart D F, Ely D G and Fox J D 1976 Effect of dietary protein, slaughter weight and sex on carcass composition, organoleptic properties and cooking losses of lamb. Journal of Animal Science 42: 575-583 http://jas.fass.org/cgi/reprint/42/3/575

Mandell I B, Buchanan-Smith J G and Campbell CP 1998 Effects of Forage vs Grain Feeding on Carcass Characteristics, Fatty Acid Composition, and Beef Quality in Limousin-Cross Steers When Time on Feed Is Controlled. Journal of Animal Science 76: 2619–2630 http://jas.fass.org/cgi/reprint/76/10/2619

Marinova P, Banskalieva V, Alexandrov S, Tzvetkova V and Stanchev H 2001 Carcass composition and meat quality of kids fed sunflower oil supplemented diet. Small Ruminant Research 42: 217–225

Nefzaoui A and Ben Salem H 2002 Cacti: Efficient tool for rangeland rehabilitation, drought mitigation and to combat desertification. Acta Horticultura 581: 295-315

Nefzaoui A and Ben Salem H 2003 Opuntia-A strategic fodder and efficient tool to combat desertification In the WANA region. Cactus (Opuntia ssp.) as forage 169: 73-90 ftp://ftp.fao.org/docrep/fao/005/y2808e/y2808e05.pdf

Negesse T, Rodehutscord M and Pfeffer E 2001 The effect of dietary crude protein level on intake, growth, protein retention and utilization of growing male Saanen kids. Small Ruminant Research 39: 243-251

Nuernberg K, Dannenberger D, Nuernberg G, Ender K, Voigt J, Scollan N D, Wood J D, Nute GR and Richardson R I 2005 Effect of a grass-based and a concentrate feeding system on meat quality characteristics and fatty acid composition of longissimus muscle in different cattle breeds. Livestock Production Science 94: 137– 147

SAS/STAT User’s guide 1989 Statistics SAS. Inst. Inc., Cary, NC.

Sents A E, Walters L E and Whiterman J V 1982 Performance and carcass characteristics of ram lambs slaughtered at different weights. Journal of Animal Science 55: 1360-1369 http://jas.fass.org/cgi/reprint/55/6/1360

Tegegne F, Kijora C and Peters K J 2005 Effects of incorporating cactus pear (Opuntia ficus-indica) and urea-treatment of straw on the performance of sheep. Conference on International Agricultural Research for Development, Stuttgart-Hohenheim, October 11-13, 2005

Titi H H, Tabba M J, Amasheh M G, Barakeh F and Daqamseh B 2000 Comparative performance of Awassi lambs and Black goat kids on different crude protein levels in Jordan. Small Ruminant Research 37: 131-135

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary fibre, neutral detergent fibre, and nonstarch carbohydrates in relation to animal nutrition. Journal of Dairy Science 74: 3583-3597 http://jds.fass.org/cgi/reprint/74/10/3583.pdf

Received 15 April 2009; Accepted 19 October 2009; Published 3 December 2009

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