The Nutritive Profile of Sun-Dried Paw-Paw (Carica Papaya) Leaf Meal and its Effect on the Growth Performance of Broiler Chickens

Abstract

In this paper, feeding trial was conducted on sixty day-old Anak broiler chicks of average weight of 204.11+3.29g for eight weeks to evaluate the effect of sun-dried paw-paw leaf meal (PLM) on their growth performance as well as proximate composition analysis on the PLM. All data collected were subjected to analysis of variance and difference in means separated using Duncan's New Multiple Range Test. The results showed that PLM contains crude protein (25.30%), crude fibre (8.86%), ether extract (0.81%), ash (8.88%), nitrogen-free extract (43.82%) and moisture (12.33%). The average daily weight gains and feed conversion ratios were not significantly different among all the treatments although demonstrated progressive numerical increase in weight gains as the PLM increased in the diets. Therefore, the inclusion of PLM up to 15% in broilers' diet is recommended for improvement in weight gain.

Headnote

Abstract: Feeding trial was conducted on sixty day-old Anak broiler chicks of average weight of 204.11±3.29g for eight weeks to evaluate the effect of sun-dried paw-paw leaf meal (PLM) on their growth performance as well as proximate composition analysis on the PLM. The birds were assigned to four treatment diets comprising T^sub 1^ (0% PLM), T^sub 2^ (5% PLM), T^sub 3^ (10% PLM) and T^sub 4^ (15% PLM) in a completely randomized design. They were replicated thrice with 5 chicks per replicate. All data collected were subjected to analysis of variance and difference in means separated using Duncan's New Multiple Range Test. The results showed that PLM contains crude protein (25.30%), crude fibre (8.86%), ether extract (0.81%), ash (8.88%), nitrogen-free extract (43.82%) and moisture (12.33%). The average daily weight gains and feed conversion ratios (FCR) were not significantly different (P>0.05) among all the treatments although demonstrated progressive numerical increase in weight gains as the PLM increased in the diets. Similar trend was also observed in the FCR where T^sub 4^(4.01) was better than T^sub 3^ (4.11) and T^sub 2^ (4.12) but not T^sub 1^ (3.92). The average daily feed intake showed a significant difference (P<0.05) when T^sub 4^ (120.69g) was compared with T^sub 3^ (119.27g), T^sub 2^ (119.24g) and T^sub 1^ (115.40g). Similarly, T^sub 1^Showed a statistical difference (P<0.05) when compared with other treatments but no significant difference (P>0.05) when T^sub 2^ and T^sub 3^ were compared in this respect. Therefore, inclusion of PLM up to 15% in broilers' diet is recommended for improvement in weight gain.

Keywords: Broiler, paw-paw leaf meal, proximate composition, growth performance.

Introduction:

The high cost of poultry feed today in Nigeria, is occasioned by the high cost of feed ingredients that supply the required protein and energy and exacerbated by the keen contest between man and animal for the same ingredients like maize, soybean, fish etc. There is, therefore, need to combat this ugly scenario by exploiting the potentials in non-conventional feed ingredients such as leaf meals that have high nutritional values and at the same time, most times wasted, such as paw-paw leaf. Leaf meal supplementation have been included into the diets of poultry as means of reducing cost of conventional protein sources and to improve protein margin (Odunsi et al., 1999; Iheukwumere et al., 2008; Adewolu, 2008; Nworgu et al., 2007; Mmereole, 2009; Wude and Berhan, 2009; Emenalom et al., 2009; Fasuyi and Nonyerem, 2007; Onyimonyi et al., 2009; Omenka and Anyasor, 2010; Ebenebe et al., 2011).

Presently, most of the poultry farms dotted all over Nigeria and some other low-income, food-deficit countries (LIFDC) have shut down due to high costs of poultry feeds (Ekenyem, 2007), thereby escalating the animal protein deficiency crisis existing in such countries (Sonnaiya et al., 1997). In the past decades, studies have been carried out to identify alternative and non-conventionalfeed resources which are cheap and easily available for poultry production (Aduku, 1993; Esonu et al., 2003; Ekenyem, 2007). Recently, attention has been drawn to paw-paw leaves as alternative protein source for livestock feed (Ebenebe et al., 2011; Onyimonyi and Onu, 2009; Adewolu, 2008; Antia et al., 2006). Vegetable-based feeds are rich sources of essential plant amino acids, vitamins, minerals, and antioxidants (Omenka and Anyasor, 2010). Further to the rich contents mentioned, it has been established that green vegetable leaves are the cheapest and most abundant sources of protein because of their ability to synthesize amino acids from a wide range of available primary materials such as water, carbon dioxide and atmospheric nitrogen (Fasuyi, 2006).

Paw-paw is a plant native to tropical America. It is known as ''okwuru bekee'' in Igbo, ''gonda''in Hausa and ''ibepe'' in Yoruba speaking parts of Nigeria (Onyimonyi and Onu, 2009). It is popular in the tropics and sub-tropics because of its easy cultivation, rapid growth, quick economic returns and easy adaptation to diverse soils and climates (Harkness, 1967; Campbell, 1984). The fruit is high in vitamins (A, B1, B2, C) and minerals (Ca, P, K, Fe), low in sodium, fat and calories and contains practically no starch (Yadava et al., 1990; IIHR, 1979). Paw-paw latex contains proteolytic enzymes- papain, chymopapain A and B, and papaya peptidase A (Yadava et al., 1990) and class 11 chitinase enzyme (Mohamed et al., 1997). This study, therefore, investigated the proximate composition of paw-paw leaf and its effect on the growth performance of broiler chickens.

Materials and Methods:

Experimental Site, Source, Processing and Proximate Composition of Paw- Paw Leaf

The experiment was conducted at the poultry unit of The Research Farm of Ebonyi State University, Abakaliki. The paw-paw leaves were got from paw-paw trees around the University's Residential Quarters and Ugwu-Achara, both in Abakaliki. The leaves were separated from the stalk, washed, drained, chopped and sun-dried for 4-6 days, till they were crispy at constant weight while still retaining the green colour. The crispy leaves were ground and used for compounding of the diets. The ground and sun-dried leaves was subjected to proximate analysis in accordance with standard methods of AOAC (1990).

Experimental Animals, Design, Diets, Duration and Management

Sixty (60) day-old Anak broiler chicks were purchased from a commercial hatchery in Abakaliki. The birds were randomly allotted to four treatments in a completely randomized design. Each treatment was replicated thrice, having five chicks each. The treatments were as below:-

T1 =Diet without paw-paw leaf meal (PLM) (control),

T2= Diet with 5% PLM,

T3= Diet with 10% PLM and,

T4= Diet with 15% PLM.

The above feeding trial lasted for 8 weeks (56 days). The poultry house was cleaned, washed and disinfected using IsolTM (cresol) and diazintolTM, allowed without stocking for 2 weeks. It was then walled with black polythene in preparation for brooding. On arrival, the day-old-chicks (DOCs) were served with a solution of glucose and vitalyteTM to serve as anti-stress after which they were served ''Top Feed'' commercial starter diet for one week which served as acclimatization period. Then the DOCs were randomly assigned to all the treatments and replicates. All routine vaccinations and bio- security measures were carried out as prescribed by the Veterinary Doctor of the University. The birds were fed twice daily ad-libitum by 7.30am and 5.30pm. Clean drinking water from the bore-hole was also offered to them ad-libitum. Between starter and finisher phases, the litter materials were replaced with fresh ones.

Data Collection and Statistical Analysis

Feed In-take: This was got daily via weigh-back mechanism by subtracting left-over feed from feed served.

Weekly Body Weight Gain: This was also measured using weekly weigh-back mechanism by subtracting the present week's weight from that of the previous week.

Feed Conversion Ratio: This was got by dividing the average total feed intake by the average total body weight gain.

All the data were subjected to analysis of variance (Steel and Torrie, 1980). Significant difference between treatments means were separated using Duncan's New Multiple Range Test (Duncan, 1955).

Results and Discussion:

The result of the proximate analysis of paw-paw leaf is presented in table 3. The result shows that the crude protein (CP) is 25.30% which is less than the reports of 30.12% (Onyimonyi and Onu, 2009) and 28.20% (Ebenebe et al., 2011) for the same leaf. This could be as a result of difference in soil, season and geographical location. It is however higher in CP than Microdesmis puberula (17.30%) (Esonu et al., 2003), cassava leaf (25.10%) (Iheukwumere et al., 2008), neem leaf (24.06%) (Onyimonyi et al., 2009), sweet potato (25%) (Wude and Berhan, 2009; Teguia et al., 1997), 23.57% and 24.85% for sweet potato leaf as reported by Adewolu, (2008) and Antia et al., (2006) respectively, as well as higher than 22.34% for mucuna leaf (Emenalom et al., 2009) and 20.59% for Amaranthus caudatus (Etuk et al., 1998; Akindahunsi and Salawu, 2005). The high protein content of PLM suggests its utilization as a protein supplement in diets for broilers (Onyimonyi and Onu, 2009). The crude fibre (CF) content of 8.86% is high when compared to 5.60% by Onyimonyi and Onu (2009) and 7.20%by Antia et al. (2006) of sweet potato leaf, 6.20% of Talinum triangulare, 6.40% of Piper guineenses, 7.0% of Corchorus olitorius and 6.50% of Vernonia amygdalina (bitter leaf) (Akindahunsi and Salawu, 2005) but lower than 24.80%, 11.40%, 12.00% and 12.93% observed for Microdesmis puberula, cassava, neem and mucuna leaves (Esonu et al., 2002; Iheukwumere et al., 2008; Onyimonyi et al., 2009 and Emenalom et al., 2009) respectively. The relative low CF makes this leaf a potential feed stuff for monogastrics(Onyimonyi and Onu, 2009). The ash content of 8.88%is however lower than some leaves in Nigeria such as 11% of sweet potato (Antia et al., 2006; Adewolu, 2008). It is however higher than some other vegetables like Occimum graticimum (8%) and Hibiscus esculentus (8%) (Akindahunsi and Salawu, 2005). The relatively high content is a reflection of its deposit of mineral elements (Antia et al., 2006). Non starchy vegetables are the richest sources of dietary fibre (Agostoni et al., 1995) and are employed in the management of diseases such as obesity, diabetes, cancer and gastro-intestinal disorders (Saldanha, 1995).

Table 4 shows the performance characteristics of broilers fed diets compounded with graded levels of paw-paw leaves. The result showed that there was no significant difference (P>0.05) among all the treatments with respect to average initial body weight, average final body weight, average daily body weight gain and feed conversion ratio (FCR). However, in respect to final body weight, the performance was numerically increasing as the inclusion levels of paw-paw leaf meal (PLM) increased from T2(5% PLM) (1821.94g bwt), T3(10% PLM) (1826.67g bwt) and T4(15% PLM) (1893.33g bwt) while the T1(0% PLM) had 1853.33g bwt. Similar trend characterised the average total body weight gain of T1 (1648.96g), T2 (1620.55g), T3 (1624.65g) and T4 (1684.67g). This trend is in contradiction with the findings of Opara (1996) and Iheukwumere et al. (2008) who found gradual decrease in average weight gains as the levels of inclusion of PLM increased progressively from 1% through 1.5% to 2%. However, this is in tandem with the work of Onyimonyi and Onu (2009) who found progressive increase in weight gain as the PLM was increased between 0.5% and 2%. Other than the control (3.92), T4 (4.01) demonstrated the best conversion of feed to meat followed by T3 (4.11) and T2 (4.12). This trend could be ascribed to the high nutritional value in terms of protein and minerals/vitamins supplied by PLM particularly when increased to 20% value. It is also most probable that the better FCR shown by control was due to lower crude fibre compared to the rest of the birds on higher fibre supplied by the PLM since fibrous diets are not well digested by monogastrics (Onyimonyi and Onu, 2009). It could also be attributed to the papain in the PLM which aid protein digestion thus enhancing the release of free amino acids necessary to enhance growth (Onyimonyi and Onu, 2009). This is in agreement with the earlier work of Poulter and Caygill (1985) that papain is an effective natural digestive aid which breaks down protein and cleanses the digestive tract. This also absolves the works of Mohamed et al. (1997) who reported that the latex of tropical paw-paw plants is a rich source of class 11 chitinase. These findings also corroborate the work of Ebenebe et al. (2011) who found increased weight gain associated with supplementation of PLM in the diet of broiler chicks. The daily feed intake also increased as the PLM progressed in percentage in the diets from T1 (115.40g), T2 (119.24g), T3 (119.27g) and to T4 (120.69g). The T1 differed significantly (P<0.05) when compared with T2, T3 and T4 but not (P>0.05) between T2 and T3. When T4 was compared to others, there was statistical difference (P<0.05). The probable reason why there was a progressive increase in feed intake with increasing PLM could be due to increasing fibre content of the feed since animals eat to satisfy their energy requirements (Sahlotaut, 1987; Blaxter, 1989; Coop and Kyriazakis, 2001).

References

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