Performance of Djallonke lambs raised under various management systems in Ghana

R Y Baiden and J L Duncan

Animal Research Institute, Box AH20, Achimota, Accra. Ghana
baidenregina@yahoo.com

Abstract

One of the major production traits of interest to sheep farmers in Ghana is lamb growth rate, as it determines how quickly they can make return on their investment.  However, the rate of growth and milk production of ruminants grazing natural pastures in Ghana are generally low.  This could be enhanced through proper feeding management systems.   The current study therefore looked at the growth performance of Djallonke lambs under four feeding management systems, NS (No supplement), S-L (Supplement to lambs) S-D (Supplement to dam) and S-LD (Supplement to both dam and lamb).  It also compared the cost of production under the various systems. 

Daily live weight gain of lambs increased by 62.73% when both dam and lamb were supplemented (S-LD) compared to the control group (NS).  The cost of concentrate per unit marginal live weight gain was similar for S-LD and S-D.  The findings of this study suggested that to enhance live weight gain of Djallonke lambs during the pre-weaning period farmers must attend to the feeding needs of both the dam and lamb.

Key words: feed, live weight, marginal cost, sheep, supplement

Introduction

Sheep is reared in Ghana purposely for meat and is raised mainly by small holder crop-livestock farmers to whom the enterprise serves as an economic empowerment. The most dominant husbandry management system is free range (where the animals are left to roam, grazing on whatever they can find) with occasional supplementation. The major production traits of interest to farmers are the number of young weaned per ewe and the growth rate.  Lamb growth rate determines how quickly the farmer gets money into his/her pocket.  However, lamb mortality is high under the free range system of production and growth rate is low (Turkson 2003).  Among the causes of mortality are starvation and poor management (Mourad et al 2001).

The Djallonke is the most predominant breed raised in Ghana.  The breed has an average birth weight of 1.89kg (DAGRIS 2005). Reported weaning weights at 90 days range from 7.4 to 11.0 kg (Armbruster et al 1991, DAGRIS 2005, Yapi-Gnaoré et al 1997), while a mean estimate of pre weaning daily weight gain is 64.89g/day (Senou et al 2009).  Average yearling weight is reported to be 20.08 kg with a range from 16.2kg to 23.3kg (DAGRIS 2005).   A slaughter weight of 30.8kg had been reported for Cameroon (Dawa et al 1996) but in Ghana it is common to have yearling rams sold for slaughter.  An overall flock productivity of 11.6kg of weaned lamb at 105 days per ewe per year has been recorded for semi-tethered flocks and 13.8kg/ewe/year for free ranging flocks (London and Weniger 1996).  Pre-weaning lamb mortality rates of 25% and 16% respectively had been reported for semi tethered and free-range management systems in Ghana (London and Weniger 1996).  The rate of growth and milk production by ruminants grazing tropical pastures or consuming crop residues alone are generally low and are said to be about 10% of the animal’s genetic potential (Leng 1997). One major reason is the imbalance nature of the nutrients that arise from digestion of such forages when they are fed without supplements.  Efforts to improve their nutrition could therefore enhance productivity.

This study investigated the effect of four feeding management systems on lamb growth (live weight gain) in Djallonke lambs during the pre-weaning period.  The study also aimed at comparing costs between the various systems.

Materials and method 

Site

The study was conducted at the Animal Research Institute’s Pokuase Research Station about 26 km north of Accra; latitude 5^o 41´ N, longitude 0^o 17´ W. The area is located within a transition zone between forest and the coastal savannah with constant high temperatures (range 29-32^oC and 29-34^oC in the wet and dry seasons respectively) and humidity ranging from 75 to 91% in the wet season and 61 to 87% in the dry season.   Rainfall is bimodal with peaks in May and September and a considerable decline in August.  January and February are the driest months.

Animals and experimental design

Twenty eight Djallonke lambs (sixteen males and twelve females) aged between four to eight weeks old were selected from a group of thirty six lambs at the Animal Research Institute’s Pokuase Station farm, Accra, Ghana.  Single born lambs from second parity ewes were selected. The lambs had an average weight of 5.79 ± 0.29 kg (Range 3 – 9.3 kg).    They were treated against external and internal parasites and randomly divided on sex, age and weight basis into four groups of seven animals each.  The four groups of animals were randomly assigned to four feeding management treatments.

The experimental design was a Completely Randomized Design (CRD) with seven replicates per treatment.

Management treatments

The four treatments were;

Treatment 1 (NS)        No Supplement

Treatment 2 (S-L)        Supplement to lamb

Treatment 3 (S-D)       Supplement to dam

Treatment 4 (S-LD)     Supplement to both lamb and dam

The chemical composition of the ingredients and the composition of the supplement are given in Tables 1 and 2 respectively.

Feeding

Lambs: All the lambs were housed under a shed and had free access to chopped Panicum maximum leaves throughout the experimental period.  Lambs taking the supplement were offered 100g (14% crude protein) on individual animal basis at 08:00 hours.  They were released to join the non-supplemented lambs on the chopped Panicum maximum leaves after they had taken the concentrate.    All lambs were allowed to suckle their dams from 12noon to 1.00pm local time. They were finally joined by their dams at 16:00hours local time and had free access to milk till the next morning.

Ewes (Dams): Ewes taking the supplement were offered 250g (14% crude protein) on individual animal basis at 08:00 hours.  The non-supplemented dams had free access to chopped Panicum maximum leaves during this period.  All the ewes were allowed to go grazing on natural pasture from 09:00 hours till 16:00hours with an hour break (from 12noon to 1.00pm local time) where they were returned to the pen for their lambs to suckle. All dams and lambs had free access to salt lick and water.  The experiment lasted for 12 weeks. The first two weeks was an adjustment period in which the animals were gradually introduced the diet by feeding more supplement every second day till they were put on the experimental ration.

Health care

All the lambs were de-wormed once every month using 10% albendazole (Arab Pesticide and Veterinary Drugs Mfg. Co., Jordan) and given Sulfadine (Arab Pesticide and Veterinary Drugs Mfg. Co., Jordan) three consecutive days every fortnight as a preventive measure against coccidiosis.

Data collection and analysis

Data collection was for ten weeks starting from the third week.  Concentrate offered and refusals were weighed daily to measure concentrate intake.   Samples of the concentrate feed and refusals were taken weekly and bulked for laboratory analysis.  Dry matter (DM) was determined according to AOAC (1970) method.  Live weight was measured weekly before morning feeding.   Marginal live weight gain due to the supplement was calculated as the difference in gain between the control treatment (T1) and the respective treatments (Marginal live weight gain = Live weight gain treatment – Live weight gain control).  Cost benefit ratio was calculated as cost of supplement (consumed) per unit marginal live weight gain.

Statistics

The data on growth performance was subjected to analysis of variance using the General Linear Model procedure of the SPSS software statistical package (SPSS Inc. 2007) to determine the effect of management treatments on the parameter. Values of P<0.05 were considered significant.  The Tukey HSD test was used to determine significant differences among treatment means. One way analysis of variance was used to compare supplement intake among treatments.

Results and discussion

Live weight change, supplement intake, marginal gain due to supplement, cost of supplement per unit live weight gain of the Djallonke lambs are presented in Table 3. 

Considering the average age (4 months) of the animals at the end of the study, the final live weights (Table 3) recorded for the various treatments fall within the range of on-station values (8.2 kg – 11.0 kg) reported for the breed by Wilson (1991) and Maehl et al (1988).  Feeding the supplement to both lamb and dam (S-LD) increased (P<0.05) lamb live weight gain by 62.73% (27.77g/day) compared to the control (NS).   A non-significant (P>0.05) increase in lamb live weight was observed when the lamb alone (S-L) or dam alone (S-D) was fed the supplement.  Similarly, the ewes (dams) fed the supplement gained slightly more weight (P>0.05) than those not offered the supplement (Table 4). 

According to Hegarty et al (2006) lamb growth rate is influenced by improved milk production from lambing to weaning which depend on good nutrition and better ewe condition.     Generally, this implied that the supplement improved milk production as well as dam and lamb live weight gain.  The results suggested that when both lamb and dam were fed the supplement there was a complementary effect between the two which was greater than when either dam or lamb alone was fed the concentrate, hence the significant (P<0.05) lamb live weight gain observed for S-LD compared to NS.

The cost of supplement per unit marginal live weight gain (Table 3) was similar for S-LD and S-D.  However, looking at the daily live weight gain (Table 3), S-LD lambs will reach market weight faster than lambs from all the other treatments. No deaths were recorded during the study.

Conclusion

• The animals used in the present study grew at a rate similar to what has been reported for the same breed by other workers. 

  
  

• The management system under which both dams and their lambs were fed the supplement improved daily live weight gain of the lambs by 62.73% compared to the system where no supplemnt was offered. 

  
  

• The cost of the supplement per unit marginal live weight gain was similar for S-LD (supplement offered to dam and lamb) and S-D (supplement offered to dam only). 

  
  

• It is suggested that to enhance live weight gain of Djallonke lambs during the pre-weaning period farmers must attend to the feeding needs of both the dam and lamb.

Acknowledgement 

The authors are grateful to the Director of the Animal Research Institute for use of the Institute’s facilities at the Pokuase Research Station for this study. The assistance rendered by the Farm manager Mr. G Aklesi and staff of the ruminant unit is very much appreciated.

References 

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Received 5 June 2009; Accepted 1 September 2009; Published 1 November 2009

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