Intake of nutrients from scavengeable resources by scavenging chickens supplemented free choice with protein and energy

L O Okitoi*,**, L W Kabuage**, R W Muinga*** and B S Badamana**

* KARI-Kakamega, P.O. Box 169, Kakamega
** Department of Animal production, University of Nairobi, P.O. Box 29053, Nairobi
*** KARI-Mtwapa, P.O. Box 16 Mtwapa, via Mombasa
oriama_okitoi@yahoo.com

Abstract

A study was conducted under farm conditions and management to estimate nutrient intake from scavengeable resources, provide information on diurnal nutrient intake and effects of supplementation with energy (maize only), protein (soybean meal) singly or together on nutrient intake. A 4 X 3 factorial arrangement of treatments comprising 4 supplementary regimes (Scavenging and offered a choice of cracked maize and soybean meal ScSM, Scavenging and offered soybean meal ScS, Scavenging and offered a choice of cracked maize ScM and scavenging only) and 3 times of crop retrieval (10.00 am, 2.00 pm and 6.00 pm). The dry weights of the crop contents obtained at 18.00 hrs were fitted into the regression equation to obtain an estimate of their dry matter intake. Nutrient intake per day was calculated as the product of dry matter intake and percent nutrients in the Crop contents.

The dry matter, protein and energy intakes (65.4, 6.4 g/d and 135 Kcal /d respectively) were below the estimated intakes of free-ranging hybrid exotic hens. Estimated protein, lysine, crude fibre and energy deficits from scavengeable resources were 67.1, 55.6, 15.6 and 0.27% respectively, thus protein and lysine were most critical nutrients in scavengeable resources. Supplementing indigenous scavenging chickens free choice with protein (soybean meal) and energy (maize meal) resulted in chickens consuming more protein to make up for the protein deficits. Nutrient (energy, protein and amino acids) intake from scavengeable resources was below the requirement of free-ranging local hens. Supplementation is inevitable to increase nutrient intake for optimum production. Offering two complementary foods is an effective method of feeding scavenging chickens allowing birds to select to meet requirements. There is a high morning (6- 2pm) intake of energy and a high afternoon (2-6 pm) intake of protein in a diurnal nutrient intake pattern. Protein and more so the essential amino acid lysine were more critical nutrients in scavenging environments with deficits of more than 50% in the scavengeable resources.

A strategic supplementary feeding strategy taking into consideration the supply of protein, more so the essential amino acid lysine and the nutrient (energy and protein) density in the morning and afternoon recommended for scavenging chickens. Carry out practically nutrient supplementation or restriction at such times in morning or afternoon to enhance feed efficiency

Key words: Amnino acids, choice feeding, feeding strategy, indigenous, local, maize, soybean

Introduction

A major challenge to increasing indigenous chicken productivity is to supply adequate and quality feeds due to inexistent feeding strategies specifically for scavenging indigenous chickens. Limited information on nutrient intake and nutrient deficits upon which to design appropriate nutrient supply for indigenous scavenging chickens hampers the optimum use of scavengeable resources and supplements to supply nutrients to scavenging chickens.  Estimating nutrient intake from scavengeable resources and supplements so that we know how much is available from the scavengeable resources and how much is required from supplements  in order to develop feeding strategies that optimally supply nutrients to scavenging chickens is essential.

Information on estimated intake of nutrients from scavengeable resources and available supplements for scavenging chickens is currently scarce. Recent studies (Ayujah 1999, Okitoi et al 1999, Tuitoek et al 2003, Kingori et al 2007 and Walker and Gordon 2003) do not accurately define the nutrient requirements of scavenging chickens.

Interest on the potential nutritional contribution of scavengeable resources and supplements has increased due to growth in outdoor and organic poultry production systems and partly due to the development of new methods to estimate feed intake of scavenging chickens. For example Tuitoek et al (2003), supported by Rashid et al (2005) by relating crop content, and feed intake using a regression model, have put one approach for estimating feed intake in scavenging systems forward. Ayujah (1999) and Kodombo (2005) explored the novel methods of determining intake by scavenging chickens. The principles underlying choice feeding behavior in fowls using cafeteria or free choice feeding as determined by Emmans (1991) and Hughes  (1984) could be used to estimate requirements in the scavenging systems, in which birds could be offered a choice of supplements with known nutrient concentrations. These have permitted more research on the subjects of nutrient intake to be conducted.

This study was an effort to estimate nutrient intake from scavengeable resources and supplements (protein and /or energy)  and to provide information on diurnal nutrient intake patterns by scavenging chickens supplemented with energy (maize meal) and protein (soybean meal). Nutrient deficits in scavenging resources were also estimated

Materials and methods 

Study area

The data used in this study were collected from farm households in the western Kenya lower midland areas of Teso and Kakamega Districts during the wet (May-August 2007) and dry seasons (Dec-Mar 2007).

Birds and management

Day-old indigenous chicken resulting from eggs collected from Busia, Kisumu, Bungoma, Vihiga and Kakamega Districts of western Kenya were incubated and hatched at KARI-Naivasha. The chicks were reared in cage brooders for eight weeks and offered chick starter mash before transferring them to KARI-Kakamega where they were reared in a deep litter house and offered a grower diet for 14 weeks.

Prophylactic measures against common diseases were taken according to the vaccination programme shown in Table 1. 

Sampling and design

Purposive sampling procedure was used to select a sample of 36 farming households. Land sizes of between 1-1.5 acres and the willingness to participate and dispose of the existing flock of chickens  to allow only tracer birds scavenge around homesteads was the main criteria.

A 4 X 3 factorial arrangement of treatments comprising 4 supplementary regimes (Scavenging and offered a choice of cracked maize and soybean meal ScSM, Scavenging and offered soyabean meal ScS, Scavenging and offered a choice of cracked maize ScM and scavenging only Sc0) and 3 levels of crop content retrieval (10.00 am, 2.00 pm and 6.00 pm)

Using completely randomized design (CRD), 12 dietary treatments were first assigned to 36 households such that each dietary treatment was replicated 3 times. Then 144 pullets at 14 weeks of age of similar weights distributed to each household such that each household received four birds.

The grower chickens scavenged for feed around the homestead. Over and above this, they were also offered supplements maize meal separately, a bean meal separately, a bean meal and maize meal free choice and no supplements in the mornings for a period of four adaptation weeks. The proximate composition of the dietary supplements is shown in Table 2.

Data collection

Fortnightly, after 4 weeks of adaptation to scavenging a bird was slaughtered in every household to retrieve crops. The crop contents were examined visually and identified to the lowest possible taxonomic category, on as-is basis and again after drying in the oven at 105oc for 48 hours.

Laboratory analysis

Chemical analyses of crop content samples were performed using the near infrared spectroscopy (NIR) methodology at KARI-Naivasha. The NIR equipment was calibrated for crop contents.

Calculations

The dry weights of the Crop contents obtained at 18.00 hrs were fitted into the regression equation DMI (g) = 22.44+ (2.25*crop content) Tuitoek et al (2003) to obtain an estimate of their DMI. Nutrient intake per day was calculated as the product of DMI and percent nutrients in the Crop contents

Patterns of nutrient intake were determined from nutrients analysed from crop content samples retrieved at 10.00 am, 2.00 pm and 6.00 pm.

Estimation of nutrient deficits in scavengeable resources as from intake of un-supplemented birds minus intake of adlibitum supplemented birds.

Statistical analysis

The data were subjected to analysis of variance (ANOVA) using the General Linear Model (GLM) procedure of SAS to measure variability among nutrients. The means were separated using Duncan multiple range test (DMRT)

Results 

The chemical composition of crop contents retrieved

The chemical composition of crop contents retrieved from scavenging chickens Table 3 shows   the concentrations of nutrients from layer crops were significantly (P<0.05) different from grower crops except for crude fat, sugar and energy. The concentrations however, did not differ (P>0.05) over the dry and wet seasons.

The concentration of nutrients from crops of chickens supplemented free choice with protein and energy (soyabean meal and maize meal) ScSM were significantly (P<0.05) higher than other supplementation regimes except for CF, STAR, amino acid lysine and ME. The concentration of energy in crop contents retrieved from un-supplemented birds (Sc0) was significantly (P<0.05) higher than for supplemented. The concentrations crude protein was significantly (p<0.05) lowest in crop contents of un- supplemented groups (ScO) compared to supplemented groups of chickens.

Supplementing with protein (soybean meal alone) and with protein and energy (soybeans and maize meal) significantly (p<0.05) increased the concentration of protein in crop contents retrieved. Supplementing with energy (maize alone) significantly (P<0.05) reduced the protein concentration on crop contents retrieved.

Dry matter intake and effects of supplementation

Estimated dry matter intake (g) of scavenging indigenous chickens supplemented free choice with soybean meal and maize meal table 4  shows Scavenging layer (adult) chickens consumed more than scavenging growing chickens 17 weeks of age.

The dry matter intakes during the dry and wet seasons were similar (p>0.05). Supplementation with protein (ScS and ScSM) increased dry matter intake (p<0.05) compared to supplementation with energy (ScM) and unsupplemented birds (Sc0) whose intake was  similar (p>0.05)

Dry matter intakes for scavenging layers supplemented with Soybean and maize free choice (ScSM) were 14.2 % higher than scavenging only (Sc0). Similar trends were recorded for growing chickens.

Nutrients intake and effects of supplementation

Nutrient intake per day Table 5 shows adult hens generally consumed more (p<0.05) amounts of nutrients than growing chickens. There was a significantly higher (p<0.05) intake of energy, protein, tryptophan and starch during the dry season.

Protein ( soybeans alone) supplementation significantly (P<0.05) increased protein intake compared to energy (maize alone) and no supplementation. Energy (maize alone) supplementation significantly (P<0.05) reduced the protein intake compared protein (soybeans only) and a combination of energy and protein (Maize and soybeans). The highest amounts of protein consumed (8.84g) were attained by supplementing protein and energy (soybeans and maize meal together) free choice.

The amino acids lysine, tryptophan methionine +cystine intake increased significantly (P<0.05) when scavenging chickens were supplemented with protein and energy (soybeans and maize meal together) free choice. The intake of amino acids when supplementing with energy (maize meal only) or protein (soybean meal only) was similar (P>0.05) to the unsupplemented groups of scavenging chickens

Intake patterns of indigenous chickens offered free choice soybean meal and maize meal

Diurnal nutrient rate of intake by scavenging chickens Table 6 shows the rate of energy intake significantly (p<0.05) higher in the morning hours and reduced significantly (p<0.05) in the afternoon at 2.00pm. Conversely, the rate of protein intake was higher in the afternoon and significantly low in the morning (p<0.05). However, the rate of intake of amino acids lysine, tryptophan and methionine + cystine was highest (p<0.05) in the morning and reduced in the afternoon.

The nutrient density in patterns showed similar trends as the rate of nutrient intake with protein appetite lowest in the early morning and highest in mid afternoon. The amino acids lysine, tryptophan and methionine +cystine were lowest in the late evening. The energy was highest in the late evening and was lowest in early morning and early afternoon.

Nutrient deficits Table 7 shows nutrient intake from scavengeable feed resources in free-range and that of birds supplemented with protein and energy ( Soybean meal and maize meal together)  deficits in all nutrients except the amino acids tryptophan and methionine + cystine, crude fat  and sugar. Crude protein was the most deficient nutrient (67.1%) followed by the amino acid lysine (55.6%).

Discussion 

The DM, energy and protein supplied from the scaveangeable resources ( 51%, 2669 Kcal/kg DM and 12.6% respectively) were within the ranges (56.4-85.8%, 2245.1-3528.1 Kcal/kgDM and 4.3-15.4%)reported by Tadele and Ogle (2002) in Ethiopia and Rashid et al (2005) in Bangladesh. The amino acids supplied from the scaveangeable resources (0.2, 0.13 and 0.17% for lysine, tryptophan and methionine +cystine respectively) were similar to those reported by Rashid et al (2005). The crude fibre supplied from the scaveangeable resources (3.84%) was lower than reported by Tadele and Ogle (2002) and Rashid et al (2005). Thus, the concentrations of the nutrients supplied from the scaveangeable resources (except CF) were similar with those reported in other parts of the world.

The protein intake from scavengeable resources (6.4 g/d} was lower than 9.48 g/d reported by Tuitoek et al (2000) and below the protein requirement of free-ranging local hens in the tropics estimated at 11g/d by Scott et al  (1982) indicating limitations of scavengeable feed resources in terms of protein supply. The crude protein intake was however 8.3% higher during the wet season.

The energy intake from scavengeable resources (135 Kcal /d} was lower than 215 Kcal/d reported by Tuitoek et al (2000) and  below the estimated energy requirement of free-ranging local hens estimated at 280 Kcal/d by Leeson and Summers (1997) indicating limitations of scavengeable feed resources in terms of energy supply.

Similarity in the calculated values of nutrients from proportions of scavengeable resources and supplements offered free choice indicates that scavenging chickens are capable of composing similar diets from a variety of ingredients offered free choice. Our observations were in accordance with the patterns of nutrient intake reported by Forbes (2006) suggesting that intake was being controlled by requirements of scavenging chickens

The increase in nutrient intake of supplemented chickens showed that scavenging chicken may be having deficits in protein  of up to 67.1%, Lysine of up to 55.6%, crude fibre of up to 15.6% and energy of up to 0.27% suggesting that protein and more so the amino acid lysine were the most critical nutrients in scavengeable resources. The increase particularly of protein supplements showed that indigenous free ranging chicken had deficits in protein and that they had a specific appetite for protein and consumed more to make up for the protein deficits

The high morning (6am- 2pm) intake of energy and the high afternoon (2-6 pm) intake of protein suggest a diurnal feeding strategy based on nutrient density for scavenging chickens. Forbes and Provenza (2000) described the internal feeling generated by intake of imbalanced food as discomfort. It has been proposed that chickens modify their intake of nutrients to minimize this discomfort. In this case, the discomfort can be speculated to be caused by under-eating protein, energy or aminoacids, threat of predation or physical environment (hot or cold weather). Scavenging chickens therefore adjust their intake to minimize the discomfort.

Conclusions 

• Nutrient intake from scavengeable resources was below the requirement of free-ranging local hens. Limitations of scavengeable feed resources in terms of nutrient (energy, protein and essential amino acids) supply was evident Supplementation is inevitable to increase nutrient intake for optimum production.

  
  

• Supplementation of scavengeable resources with both energy and protein increased nutrient intake. Therefore offering two complementary foods is an effective method of feeding scavenging chickens allowing birds to select to meet requirements

  
  

• There is a high morning (6- 2pm) intake of energy and a high afternoon (2-6 pm) intake of protein in a diurnal nutrient intake pattern. Practically nutrient supplementation or restriction is carried out at such times to enhance feed efficiency

  
  

• Protein and more so the essential amino acid lysine were more critical nutrients in scavenging environments with deficits of more than 50% in the scavengeable resources. Proteins and more so amino acids should be considered in formulating supplementary feeds for scavenging chickens

Acknowledgements 

The study was supported by the Kenya agricultural productivity programme (KAPP) through the Kenya Agricultural Research Institute (KARI) as a part of a PhD grant for the first author

References

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Received 18 April 2009; Accepted 8 May 2009; Published 3 December 2009

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