Effect of feeding differently processed detoxified neem (Azadirachta indica) seed cake based complete diet on growth, nutrient utilization and carcass characteristics in Nellore sheep  

K Madhavi, T J Reddy, Y Ramana Reddy and G V N Reddy^*

Department of Animal Nutrition, College of Veterinary Science, ANGR Agricultural University, Rajendra Nagar, Hyderabad 500 030, India
*College of Veterinary Science, Sri Venkateswara Veterinary University, Tirupati - 517 502, India
ramanayr19@yahoo.co.in

Abstract

A complete diet was formulated using detoxified neem (Azadirachta indica) seed cake and processed into mash, expander extruded pellets and steam pellets. These three diets were evaluated in comparison to a conventional ration in a 180-day growth and metabolism trial using twenty four Nellore ram lambs (18.81±0.51kg) divided into four groups of six lambs each, in a Completely Randomized Design (CRD). At the end of growth trial three ram lambs from each group at random were slaughtered to study the carcass characteristics.

The average daily gain was significantly (P<0.05) higher and cost/kg gain was lower in pelleted diets in comparison to control and mash diets. DMI was significantly (P<0.01) lower in lambs fed complete mash ration compared to those fed control and pelleted rations. Pelleting significantly increased the digestibility of OM, CF (P<0.05) and CP (P<0.01). Positive N, Ca and P balances were recorded on all the diets and N and Ca balances were significantly (P<0.01) higher in pelleted diets in comparison to control and mash diets. The DCP and TDN values of the diet was significantly (P<0.01) increased by processing the NSC based complete diet into pellets. Increased trend in intakes of DM, DCP and TDN were observed in lambs fed pelleted rations than mash and conventional ration. Significant (P>0.05) differences with regard to dressing percentage, primal cuts, proportion of lean, bone, fat and edible and inedible organs was not observed among the lambs fed experimental diets. But increased trend in dressing and lean percentage with concomitant decrease in proportion of bone and fat in lambs fed pelleted diets was observed.

Hence, neem seed cake, an unconventional feedstuff, can be incorporated into complete diets after detoxification without any deleterious on growth and meat quality. Among pelleting methods, expander-extruder processing can be preferred over steam pelleting since the processing cost is less compared to steam pelleting.

Key words: carcass characteristics, Neem seed cake, nutrient utilization, performance, processing, sheep

Introduction

Small ruminants in India are mostly reared by the weaker sections of the society, who find it difficult to feed their sheep and goat on costly conventional oil seed meals. Hence, reduction in investment by incorporating hitherto wasted and unutilized agro-industrial by-products as protein supplements need to be scrutinized. Neem (Azadirachta indica) seed cake, an unconventional feed, is a good source of protein (30-40% CP) for livestock and available to an extant of 0.9 million tons in India (Singh 1993). The protein in cake is relatively balanced in its amino acid content and mineral profile (Gowda and Sastry 2000). Despite high CP content, its incorporation in animal diets was discouraged due to their adverse effect on production traits because of presence of bitter and toxic triterpenoids, mainly nimbin, nimbidin, azadirachtin, and salanin (Paul et al 1996). Further, feeding such ingredients may impart unpleasant taste or smell to meat (Clausen et al 1985). Debitterization through solvent extraction, water washing, alkali soaking and urea-ammoniation has been tried with appreciable success (Gowda and Sastry 2000). In addition, the palatability and utilization of unconventional feedstuffs can be improved by incorporating into complete diets and processing into pellets (Reddy and Reddy 1999). Hence, in the present study an attempt has been made to examine the growth rate, nutrient utilization and carcass characteristics in Nellore sheep in a long term feeding of such unconventional feedstuffs after detoxification and processing into complete diets such as mash, steam pellets and expander-extruded pellets.

Materials and Methods

Site of study

The study was carried out at the College of Veterinary Science, S.V. Veterinary University, Rajendranagar, Hyderabad, India (17^o 12′ N, 78^o 18′ E, 518 m above mean sea level). The mean rainfall in the region was 750 mm.

Experimental feeds

A complete diet was formulated with water washed (1:15 w/v) and urea -ammoniated (4% urea, 40% moisture with incubation period of 14 d) neem seed cake at 15% level (Table 1) using bajra (Pennisetum americanum) straw (28.5%) and groundnut (Earaches hypogaea) haulms (10%) as roughage source and processed into mash by grinding through 8mm sieve in a hammer mill.

Then one third of the mash was subjected to steam pelleting and another one third to expander extruder processing. These three processed NSC based complete diets were evaluated through growth (180 d) and metabolism trial using Nellore ram lambs in comparison to a conventional control ration containing concentrate mixture and chopped jowar (Sorghum bicolor) straw.

Experimental animals, housing and feeding management

Twenty four healthy, Nellore ram lambs with an average body weight of 18.81±0.51kg were randomly allotted to 4 groups of six animals each in a Completely Randomized Design (CRD). All the lambs were dewormed and vaccinated against enterotoxaemia prior to initiation of the study and maintained in well ventilated individual pens (4mx3m) with facilities for feeding and watering. The processed diets were offered ad lib twice daily at 8.00 and 14.00h during the experiment period. In case of control group quantity of concentrate offered was adjusted fortnightly according to body weight to meet the protein requirements (Ranjhan 1993). Clean drinking water was made available ad libitum through out the study for the experimental animals.

Growth and metabolism trial

Daily feed intake and fortnightly body weights for two consecutive days in the morning before feeding and watering were recorded through out the 180 days of experimentation. In the middle of the experiment the lambs (32.02±0.84 kg) were transferred to individual cages with feeding and watering arrangements and conducted metabolic trial following 7 day adaptation period and 7 day collection period. During the collection period feed intake of each animal was quantified based on feed refusal of each day. Samples of feed offered and residues leftover were collected in separate polythene bags for each animal daily for chemical analysis. Faeces and urine voided during the 24 h were collected and measured at 8.00 h. A 10 per cent (w/w) aliquot of faeces in a polythene bag was frozen at -20^oC for each animal. An aliquot of 5 per cent urine was collected daily and preserved at 4oC after the addition of few drops of concentrated HCl. After completion of the collection period, frozen faecal samples were thawed, mixed thoroughly and sub-sampled for N and DM determination. For further chemical analysis, feed and faecal samples were dried and ground through a 1 mm screen in a Wiley mill and processed in air tight bottles.

Analytical procedures

The feed, faeces and urine samples were analyzed for N using Turbotherm and Vapodest (Gerhardt, Germany) analyzer based on the principle of Micro-Kjeldahl method (AOAC 1997; Procedure No. 4.2.02). Dry matter (DM), total ash (TA), ether extract (EE) and crude fibre (CF) were estimated according to according to the procedure No.4.1.03, 4.1.02, 4.5.01 and 4.6.01, respectively as described by AOAC (1997). Calcium was estimated by Systronic flame photometer 128 (FPM compressor 126 1999) and phosphorus was estimated by colorimetric method (AOAC 1997). DE and ME values were calculated using the conversion factors (NRC 1978).

Slaughter studies

After growth trial, three animals from each group were randomly selected to study the carcass characteristics. Animals were slaughtered by "Halal method" after starving overnight. The live weights before slaughter were recorded. The sticking, legging, dressing and evisceration were performed as per the procedures described by Gerrard (1964).Weight of hot carcass, different wholesale cuts, edible (liver, heart, testes, diaphragm, kidney and spleen) and non-edible (blood, lungs, trachea, stomach and intestines) offals were recorded. The weight of fat, muscle and bone of each trimmed cut were recorded separately from left side of the carcass.

Statistical analysis

The experimental data were subjected to least square analysis of variance (Snedecor and Cochran 1968) and the treatment means were tested for significance by Duncan's multiple range test (1955).

Results and Discussion

Chemical composition

Processing did not affect the chemical composition of complete diet (Table 2), corroborating with the findings of Reddy and Reddy (1999) and Reddy et al (2002).

Growth rate and feed efficiency

Lambs fed mash ration recorded significantly (P<0.05) lower final body weight, weight gain and average daily gain (ADG) where as those fed pelleted rations recorded higher (P<0.05) values than the control ration (Table 3).

There was 8.08 %, 8.49% decrease and 4.91% increase in feed intake per kg gain in lambs fed expender extruded pellets, steam pellets and mash diet, respectively in comparison to those fed control diet. Pelleting of mash ration improved daily weight gain and reduced feed per kg gain in lambs and kids compared to conventional ration (Reddy and Reddy 1991a; Reddy and Linga Reddy 2003). Higher ADG and better feed efficiency were also reported in post weaned calves, steers and sheep (Serrano et al 1998; Reddy and Reddy 1999; Weir et al 1959; Bush et al 1978) fed processed diets. Increased palatability and digestibility of pelleted rations together with efficient utilization of absorbed nitrogen may be responsible for increased ADG and feed efficiency in pellet fed animals (Nicholson et al 1996; Reddy and Reddy 1999; Reddy et al 2002). In addition, Esplin et al (1957) postulated that beneficial results from pelleting were probably due to more exact control of the concentrate to roughage ratio and improved palatability rather than increase in nutritive value. Poor feed conversion efficiency and lower ADG in lambs fed mash diet was attributed to lower DMI, which is due to sorting of fine and bitter particles of NSC in mash diet.

Cost of feeding

The cost of feed/kg was lower for complete diets than conventional ration due to inclusion of low cost unconventional feeds like NSC and bajra straw (Table 3). High cost of pelleted diets compared to mash diet was due to additional cost involved in processing. The cost of feed/kg gain was reduced by 4.52, 15.50 and 14.95 per cent in lambs fed complete mash, expander extruded and steam pelleted diets, respectively compared to conventional ration (Table 3). Cost of feed/kg gain was comparable between pelleted diets but was less on pelleted diets than conventional and mash rations. Similar results of reduced cost per kg gain on processed diets were reported in sheep (Bush et al 1978; Ramu et al 1994) and calves (Reddy and Reddy 1999; Reddy et al 2002). This may be due to high feed efficiency and low cost of processed complete diets due to incorporation of cheaply available unconventional feeds. Though FCR was poor on mash than conventional ration, cost of feed per kg gain was less for mash ration due to low cost of ration/kg.

Dry matter intake

The DMI was significantly (P<0.01) different among the diets and lower on NSC based mash ration compared to other three diets (Table 4).

Bedi et al (1975) and Ludri and Arora (1977) also reported decreased DMI on NSC based diets. Lower DMI of mash ration may be due to sorting of fine and bitter NSC particles, but this effect was largely overcame by pelleting. Hence, there were no significant (P>0.05) differences in DMI among conventional, expander-extruded and steam pelleted diets. Similar results were recorded by Nicholson et al (1996) when crab meal based diet was pelleted. Increased DMI of pelleted rations may be due to reduced dustiness and increased palatability due to processing (Skoch et al 1983).

Digestibility of nutrients

Digestibility of DM, EE, NFE did not differ significantly (P>0.05) among the diets, but there is increased trend in digestibility towards pelleted rations (Table 4). Digestibility of OM, CP, CF was significantly (P<0.05) higher in pellet fed lambs as compared to control and mash fed lambs. Pelletization of complete feed, improved digestibility of nutrients (Reddy and Reddy 1984, 1994; Reddy et al 2003). Pelleted rations showed higher digestibility due to processing effect, which could alter the cellulose from a crystalline structure to a more digestible amorphous state and also long chain cellulose would be broken down by heat and pressure, leaving segments more vulnerable for bacterial action (Jahn and Kamstra 1960). Pelleting also gelatinizes starch, thus making it more susceptible to enzymatic digestion (Jensen and Becker 1965).

The DCP and TDN contents were significantly (P<0.01) higher in pelleted diets in comparison to mash and control diet (Table 4). In similar studies, pelleting significantly (P<0.01) increased the DCP and TDN content (Ibrahim et al 1998; Reddy et al 2002; Reddy et al 2003). Higher DCP and TDN values recorded on pelleted diet compared to mash and conventional diet was reflection of pelleting effect (Reddy and Reddy 1998) which resulted in higher OM and CP digestibility. However, Lindahl and Davis (1955) reported only small increase, while Weir et al (1959) reported no increase in TDN content due to pelleting.

Balance studies

All the experimental animals were on positive nitrogen (N), calcium (Ca), phosphorus (P) balances (Table 5).

Significantly higher N retention was observed in lambs fed expander extruded and steam pelleted NSC based diets than those fed mash and conventional diets. Increased N retention due to pelleting was reported (Ibrahim et al 1998; Reddy et al 2002) and this was attributed to processing effect (Reddy and Reddy 1983), and another reason being the availability of matching supply of energy to rumen microbes on these rations (Reddy and Reddy 1991b). Ca retention was significantly (P<0.05) higher in lambs fed complete diets compared to those fed mash and conventional ration. These findings are in agreement with the findings of Ibrahim et al (1998) and Reddy et al (1992). This may be due to processing effect in pelleted diets as compared to mash diet and control ration. Significantly higher calcium retention on pelleted rations was reflection of higher intakes of this mineral (Reddy and Reddy 1991c). In contrast, Ca balance was not influenced by processing of complete diets in calves and sheep (Reddy and Reddy1991a; Reddy and Reddy 1999; Reddy et al 2002). Processing had no significant (P>0.05) effect on P balance and this finding is in accordance with the other studies (Reddy and Reddy 1999; Reddy et al 2002). In contrast Ibrahim et al (1998) Reddy and Reddy (1991a) reported higher P retention due to pelleting of diets.

Nutrient intake

DCP (g) and ME (MJ) intake per kg metabolic body weight were 5.98 to 7.86 and 0.63 to 0.86 in lambs fed experimental diets. The intakes were higher in pellet fed lambs and lower in mash fed lambs than those fed conventional ration (Table 5). Lambs on rations except mash could meet their DCP, TDN requirements according to ICAR (1998) standards. ICAR (1998) has recommended 6.71g DCP and 0.71MJ ME per kg metabolic body weight.

Slaughter studies

Dressing percentage on live weight and empty body weight basis varied from 50.51% to 52.42% and 56.72% to 60.06%, respectively and didn't differ significantly among the groups (Table 6).