Restricted feeding of Pekin ducks: a comparison of three levels of quantitative feed restriction and full feed on the growth, carcass and economic indices

J K Q Solomon, R Austin and R N Cumberbatch

Department of Livestock and Pasture Production, National Agricultural Research Institute,
Mon Repos, East Coast Demerara, Guyana South America
k_jaham@yahoo.co.uk   ;   robinastn@yahoo.com   ;   richnigcumb@yahoo.com

Abstract

This experiment was conducted to evaluate the performance of Pekin ducks on three levels (L65, L74, L82) of restricted feeding (65, 74 and 82%) as against full feeding (L100=100%). Sixty F₂ Pekin ducklings of male sex were selected and used in this experiment. Five ducklings were randomly selected and placed in a unit with three replications in a completely randomized design. Ducklings were weighed individually and body weight recorded on a weekly basis.

There were no significant differences between L82 and L74 for mean live weight at 56 days old;  however, L65 recorded significantly lower mean live weight at 56 days than L100, L82 and L74 respectively (P<0.05). There were no significant differences in feed conversion rates for birds under the four levels. In relation to carcass indices,  similarities were observed among the four levels. L100 had the highest profit margin followed by L82, L74 and L65 respectively.

Key Words: Carcass, economic indices, growth, Pekin ducks, restricted feeding

Introduction

Feed utilization accounts for approximately 72% of the total cost of production for Pekin ducks reared intensively on commercial feed in Guyana. Pekin ducks are generally considered large and wasteful consumers of feed. This practice or trait of Pekin ducks makes many farmers unable to raise these ducks on commercial feeds, particularly those in the rural communities where the cost of feed is expensive as a result of the high cost of transportation,.

In a previous study, on a comparison for live weight and carcass gain of Pekin, Kunshan and Muscovy ducks on a commercial duck ration (Solomon et al 2001), Pekin ducks consumed approximately 7.11 kg feed from day 1 to 56 days old on free choice basis. Perez (1985) in a manual on duck production reported that Pekin ducks would generally consume between 7.9 and 9.0 kg dry feed up to 56 days of age.

Therefore, many farmers use locally available agro-industrial by-products or table scraps as a cheaper means of raising their ducks with far less success, mainly because of inadequate nutrition. This practice results in the ducks taking a longer time to reach market weights, with some farmers reporting a range of four to six months to attain a market weight of 2.3 kg live weight. The slow growth rates have led not only to a reduction in capital invested but also it is more costly to raise Pekin ducks due to the extended duration of feeding to meet desirable market weights.

The concept of restricted feeding of Pekin ducks has been postulated as an approach that may assist the farming community particularly the rural farmers in reducing the time and cost of rearing ducks. The demand of the consuming populace was also influential in determining this study because the market for ducks in Guyana is one where ducks are purchase predominantly live and the buying populace may find it too expensive to purchase the larger size ducks and thus may be able to purchase ducks at the same age with less weight.

This concept it is envisaged could attract farmers at the different levels or tiers of the production chain, i.e. farmers who could afford to full feed their ducks thus allowing for maximum weight at the market age of 56 days or farmers who would practice restricted feeding up to 56 days, and thereby marketing a duck at a reduced weight and thereby being able to meet the demand of the consumer.

Therefore, if an increase in duck rearing is to be encouraged, strategies would have to be developed to lower feed cost of production. In this study, the intended focus was to test the concept of restricted feeding as a possible and viable option for farmers in the low economic range.

Thus, the objectives of this study were to:

• Compare the growth rates of Pekin ducks on varying levels of feed restriction as against full feed supply.
• Evaluate the carcass traits of the ducks under the four feed treatments.
• Conduct a cost benefit analysis of the treatments used.
   

Methodology

Site description

This study was conducted at the National Agricultural Research Institute, Livestock Farm Mon Repos on the East Coast of the county of Demerara, approximately 20 km from the capital city Georgetown. The area has two wet and two dry seasons. Rainfall per annum ranges between 2,300 and 2600 mm. During the wet season, the duration of sunshine averages 5 hours per day, but during the dry season, it is about 7 hours or more per day. The daily temperature during this study averaged 30.6⁰C and relative humidity was from  70 to 80%. Usual wind movement is in a northeasterly direction at velocity of about 10-15 m per second.

Animal selection and management

Sixty male Pekin ducklings were selected and wing-banded for individual identification. Five ducklings were randomly selected and placed in each pen with 3 replications (pens) in a completely randomized designed study.  The pens were adjustable to facilitate the brooding and growing period, and were made safe from predators. The floor was smooth concrete and roof of zinc sheets with extended eaves to prevent rain from blowing into the pens. The walls from the floor to a height of 75 cm were made out of wood, and the wall height up to the roof was made of chicken mesh. This type of arrangement allowed for good ventilation. The experimental period was  eight weeks.

Treatments

The feeding levels were: L 82,  L74, L65 and L65, representing 82, 74 and 65%  % of the recommended consumption (L100) of Pekin ducks. This feeding regimes for the three restricted levels were derived from the average (7.78 kg) of  total feed consumption of 7.11 kg, quoted by Solomon et al (2001) and 7.9 to 9.0 kg, recommended by  Perez (1985).  In the control group, the birds were given feed in excess of ad libitum consumption. The birds were fed once daily at 08:00 hrs on a set feeding regime described in Table 1.

Brooding

Rice hulls were used as the bedding material. An infrared lamp provided heat in the individual pens. Wind and air drift during the first two weeks were controlled by curtains placed around the pen. These curtains were rolled down at night and whenever rain fell; adjustments were also made as the birds grew older. In this phase a starter ration with 21% crude protein (CP) in the form of dry feed was given from day one to 14 days of age. The ducks were provided with feeding and watering space of 2-5 cm and 2-4 cm respectively depending on their age during this stage. A floor space of 930 cm² per duckling was provided. Water was made available ad libitum throughout the experimental period. Vitalyte booster at a rate of 0.75 grams per litre was added to the water for the first 3 days.

Growing management

After the brooding phase of two weeks the ducklings were given a floor space of 2323 cm² per bird and feeding and watering space of 6 cm and 5 cm respectively. A pelleted grower-finisher feed with 16% CP was gradually introduced at this stage until the completion of the trial.

Ingredients of the rations

The rations (Table 2).were obtained from a commercial supplier and were based on grain products, vegetable protein products, grain processing by-products, vitamin A supplement, vitamin D 3 supplement, vitamin E supplement, calcium carbonate, dicalcium phosphate, salt, traces of zinc oxide, manganese sulphate, iron sulphate, calcium iodate, copper sulphate, sodium selenite and Ethoxyquin (Preservative).

Measurements

Ducklings were weighed individually on a weekly basis. Feeds offered and refused were recorded daily.At the end of the study, 40 % of the birds in each level was randomly selected and slaughtered to determine carcass traits.

Statistical analysis

 The data for live weight gain, feed conversion ratio and carcass traits were analyzed by  ANOVA for Completely Randomized Designs, using the General Linear Model (GLM) procedures of SAS (1985) with significance set at (P<0.05). Duncan's Multiple Range test was used to determine significant differences between levels.

Results and discussion

Final live weights and growth rates decreased linearly as feeding level was reduced (Table 3 and Figures 1 and 2) but there was no effect of feeding level on feed conversion.

 

This trend continues up to day 21 except that at day 14, L74 though not significant had started to gain higher live weight than L65. Observation from day 28 to 49 showed a similar trend where all four levels were different from each other L100 > L82 > L74 > L65 (P<0.05).

L100 at day 56 of the study was significantly higher for live weight than L82, L74, and L65 respectively. There were no differences between L82 and L74 for mean live weight when the ducks were 56 days old, however, L65 recorded significantly lower mean live weight at 56 days than L100, L82 and L74 respectively (P<0.05).

The growth rate of ducks in this study confirms the observation made by Dean (1985) that there is a progressive reduction in weight gains of ducklings as the intake of a complete diet was reduced in increments of 3 % from 0 to 9 %. In this study, as the level of feed restriction increases growth rate decreases. This trend also confirms to a study reported by Osman (1993) that feed restriction retarded body weight gain from 3-10 weeks (P<0.05), birds fed ad libitum had a higher body weight at slaughter. Loktionov and Kovatskii (1993) also reported that feeding replacement drakes during the first seven weeks of life at level of 30% below normal affected their growth. As cited by Dean (1985), Leclercq and de Carville stated that the reduced weight gain associated with feed restriction corresponds mainly to a reduction in carcass fat and that the weight of the thigh and breast muscle decreased very little.

There were no differences in feed conversion rates of the ducks under the four levels (P<0.05).

Bochno et al (1991) reported significantly better feed conversion for ducks fed 75% of full feed when compared to ad libitum feeding. The results in this study for feed conversion ratio though better for L65 and L74 did not differ statistically as was reported above. The feed conversion trends observed in this study suggested that ducks gained weight in relation to their feed intake on a complete diet, which may explain why there were no statistical differences in the feed conversion ratios of the four levels (Figure 2.)

There were no differences for mean carcass weight in L100, L82, and L74, no differences were also detected in L82, L74 and L65 however; L65 had a significantly lower mean carcass weight than L100, Table 4.

There were no differences between mean carcass percentages among the four levels. There were no differences for mean breast weight between L82, L74 and L100; however L65 breast weights was significantly lower than the three other levels.

The mean leg and thigh weight did not differ statistically in L100, L82, and L74. L82, L74 and L65 also did not differ from each other; however L65 was significantly lower than L100 for mean leg and thigh weight. This identical trend was observed for mean fat weight among the four levels. (Table 3)

These results suggests that feed restriction levels of 18% and 26% below ad libitum do not have any significant effect on carcass traits when compared to full fed birds, however, at 35% below ad libitum feeding carcass traits were significantly lower than full feed with one exception in the case of carcass percentages. The absence of differences in carcass percentages reported in this study suggests that carcass percentage index are relatively constant in the Pekin breed of ducks regardless of feeding regimens and body weight differences. Bochno et al (1991) reported similar carcass percentages as those obtained in this study. At 35% less ad libitum only then feed restriction had a significant impact on breast weight, thigh and leg weight and fat weight in comparison to full fed ducks and in some instances the two other levels of feed restriction.

Osman (1993) also confirmed the results obtained in this study for L82 and L74, in Osman study feed restriction levels were not significant between the feeding groups and ad libitum feeding for breast and leg meat.

Feed restriction did not impact on mortality as no bird under the three levels of feed restriction died during the study, only one bird died and that was in the full feed level, representing 6.6% mortality in L100. Mazanowski and Kokoszynski (1999) reported that feed restriction 30% lower than ad libitum feeding had a negative effect on the survival rate of ducks, a condition not experience in this study. Osman (1993) reported no differences for mortality among the groups fed restricted feed compared to those on ad libitum feed supply.

L100 had the highest profit margin followed by L82, L74 and L65 respectively. Cost to produce 1kg live weight and cost per unit gain was more economical in L100 followed by L82, L74 and L65 respectively (Table 4).

Conclusions

• This study gives duck farmers options in relation to raising Pekin ducks locally.
• live weight gain was in accordance with total feed intake although L82 and L74 did not differ statistically in relation to weight at the end of the study.
• The comparison for carcass index showed that there were differences and similarities observed among the 4 levels.
• The differences in live weight mitigate for the differences observed for total feed intake for both feed conversion and profitability.
  

Acknowledgement

The authors wish to express our appreciation of the kindness of Mr. C. R. Paul (Biometrician) in analyzing our data from the experiment.
 

References

Bochno R, Lewczuk A and Wawro 1991 Effect of ad libitum and restricted feeding on growth and carcass quality of ducks. Cab International Poultry Abstracts 1991 Volume 17 Number 8 (2180) pp 272.

Loktionov V and Kovatskii N 1993 Restricted feeding of ducks. Cab International Poultry Abstracts 1993 Volume 19 Number 6 (1514) pp 172

Mazanowski A and Kokoszynski D 1999 Effect of restricted feeding from 4-20 weeks of age on duck performance before and during reproduction. Cab International Poultry Abstracts 1999 Volume 25 Number 11 (3633) pp 456

Osman A M A 1993 Effect of quantitative feed restriction on growth performance, carcass traits and meat quality of male Pekin ducks. Cab International Poultry Abstracts 1993 Volume 19 Number 12 (3238) pp 372

Perez R 1985 Duck - Rearing manual, University of the West Indies, St Augustine, Trinidad.

SAS Institute1985 User's Guide: Statistics version 5 Edition. SAS Institute Inc. Nc.

Solomon J K Q, Austin R and Cumberbatch R N (2001) A comparison of live weight and carcass gain of Pekin, Kunshan and Muscovy ducks on a commercial ratio. Unpublished National Agricultural Research Institute. Annual Report 2002.

Received 21 September 2006; Accepted 26 May 2007; Published 6 July 2007

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