Influence of weaning age on the growth performance and survival of weaned guinea pigs

F A Fonteh, A T Niba, A C Kudi^*, J Tchoumboue and J Awah-Ndukum

Department of Animal Production, Faculty of Agriculture, P.O Box 222 Dschang, Cameroon
fontehflorence@yahoo.com;   atniba@yahoo.fr
^*Seale-Hayne, Faculty of Agriculture Food and Land Use, University of Plymouth, Newton Abbot, Devon TQ12 6NQ, United Kingdom

Abstract

A study was carried out to investigate the influence of weaning age on the growth performance and survival of Guinea pigs in the western highlands of Cameroon between March and September 2003. 94 kids from 56 breeding females were used for the study. Breeding females were divided into four groups corresponding to the different weaning ages for kids (Treatments) and designated as: T21 = weaning at 21 days; T16 = weaning at 16 days; T11 = weaning at 11 days and T84 = no weaning until 84 days of age. Kids were fed ad libitum with fresh forage mainly Pennisetum purpureum and supplemented daily with a mixture of wheat bran, palm kernel cake and vitamin/mineral premix.

Overall weaning weight was significantly higher (P<0.05) for kids weaned at 84 days of age than in any other treatment. However, the mean daily weight gain was highest (2.48 ± 0.16 g) for kids weaned at 11 days of age and lowest (1.70 ± 0.11 g) in kids weaned at 84 days. The greatest survival rate was recorded in kids from T21 (83.33%) while the lowest rate (62.65%) was in T84. The fastest changes in live weight after weaning were observed in T16, closely followed by T21 and the slowest was in T84. Similarly, the highest mean litter size was observed in T16 (1.4 ± 0.11) while the lowest was in T84 (1.1 ± 0.07).

In conclusion, early weaning in guinea pigs will bring about significant improvement in kids' growth performance and survival. Where efficient feeding strategies can be developed, weaning at 11 days of age will permit an increase in the overall productivity and economic returns.

Key words: Guinea pigs, growth performance, survival rate, weaning age

Introduction

Guinea pigs have been shown to play a vital role in the animal protein supply and income generation in rural areas in Cameroon (Ngou Ngoupayou et al 1994; Manjeli et al 1998). In these regions, production is mainly by traditional means. Traditional guinea pig farming appears to be a secondary household activity undertaken by small farmers basically women (Ngou Ngoupayou et al 1994). Such an extensive production system which shows no defined management practices, integrates very well in the agricultural systems (small livestock, food crops and natural forages production) of the Western highlands and Southern forest zones of Cameroon.

Under such a system, guinea pigs are reared in polygamous groups. This leads to a situation where mismanagement contributes to post-partum matings and inbreeding of stock (Nuwanyakpa et al 1997). Uncontrolled breeding does not only lead to some females being bred too early, but also the perpetuation of inferior genotypes resulting in low conception rate, low birth weight and kid survival (Manjeli et al 1998) and/or inbreeding depression.

Journet-Boullery (1986) and Cicogna (2000) have observed high post-partum fertility rates associated to breeding just a few hours after birth for reproducing females. This is often seen in the kidding interval duration being equivalent to the average gestation length. Under such circumstances, females are faced with high reproduction pressure, as well as demands for their maintenance needs and lactation for the newborn.

The application of better management strategies such as improved feeding, elimination of precocious breeding and early weaning could reduce these pressures on the females. Early weaning of kids is likely to permit adequate feeding for kids (improving growth and survival) as well as reducing the demand on the body reserves of dams. This paper, therefore, assesses the influence of managing weaning age on growth performance and survival of kids.

Materials and methods

Study site

The study was conducted at the teaching and research farm of the University of Dschang. Dschang is situated in the western highlands of Cameroon, which is in the Sudano - Guinean zone (latitude 5 - 7⁰ N, longitude 8 - 12⁰ E). The mean annual temperature and relative humidity range is 16 - 17⁰ C and 49 - 97% respectively. The mean annual rainfall is about 2000 mm, the wet season ranges from March to November and the dry season from late November to March.

Trial management

The study was done using a total of 94 kids from two age groups of breeding females comprising twenty-four dams aged between 18-20 months old and thirty-two young dams 8-10 months old. The experiment lasted for 7 months (March to September 2003). Breeding females were divided into four groups corresponding to the different weaning ages for kids (Treatments). There were two replicates per treatment (one made up of 6 old dams and another of 8 young dams). Replicates for old and young dams were placed in adjacent pens.

These treatments were designated as follows;

T21 - Weaning at the presumed weaning age of 21 days;
T16 - Weaning at 16 days of age;
T16 - Weaning at 11 days of age;
T84 - No weaning until 84 days of age

After weaning, kids were housed in identical rabbit type cages of 0.45 m² and height 0.26 m (L-0.97m, W-0.46 and H-0.26) at 5 kids per cage. The cages were cleaned daily to avoid accumulation of urine and faeces.

Kids were treated against ecto-parasites with DIDETEKI^® every five weeks and coccidiosis with an anti-coccidian (VETACOX^®) every month for three consecutive days.

Feeding management

Kids were fed ad libitum with fresh forage mainly Pennisetum purpureum and supplemented daily with a mixture of wheat bran, palm kernel cake and vitamin/mineral premix (Agricare broilers-mix 0.25%). The quantity of supplement given was adjusted to 5% of the average live body weight of animals in each treatment. The proximate chemical composition of the basal and test diets were determined according to the methods described by A.O.A.C. (1984) are shown in Tables 1 and 2.

Data collection and statistical analysis

Data on birth weights, weaning weights and weekly weights were recorded for the growth performance according to the parity and age of dams. In case of twins, average values were used in the analysis. Birth weights were recorded within 12 hours after kidding and at weaning using an Ohuas-triple beam balance (with a precision of 0.1 g). Weaning weights for treatment T84 where however recorded at the presumed weaning age of three weeks and kids were left with the dams until twelve weeks of age.

Comparisons within treatment between parities were analysed using the student's t-test while comparisons of data between treatments were subjected to analysis of variance. Significant means were separated using the Duncan's multiple range test (Steel and Torrie 1980).

Results

Effect of weaning age and parity on the weaning weights (g) of kids

Overall mean values for weaning weights showed weaning weights to range from 157.0 ± 9.25 for treatment T84 to 120.31 ± 5.68 for treatment T16 (Table 3). These lower values for means of treatment T16 corresponded with earliest weaning (11 days) as opposed to T84. It was also observed that overall lowest weaning weights were associated with treatment T21 and T16 (120.31 and 135.43 g respectively). The overall mean value for weaning recorded for treatment T16 where weaning was done at 16 days of age was higher than those of T21 (21 days). The overall mean difference in weaning weight at 11 days was lower by 15.12 g as opposed to weaning at 21 days but when weaning at 16 days was considered, an increase of 6.27 g was observed. The overall combined mean difference in weaning weights between early weaning (T16 plus T16) and weaning at the presumed weaning of 21 days and weaning at 84 days (T84 plus T21) was 30.42 g, where the sum of T84 and T21 was higher. The overall mean value obtained for treatment T84 was significantly (P<0.05) higher than the other treatment groups.

Independent of parity, no significant differences in mean weaning weights were observed between treatments for old dams although the mean for T16 was lowest and for T21 highest. For young dams, significant (P<0.05) differences were observed between T84 and T16  and both were significantly (P<0.05) higher than either T21 or T16. However, no definite trends were observed for the parities. Considering the age of dams, a significant (P<0.05) variation in mean weaning weights was observed between old and young dams in treatments T21, T16 and T84. Old dams of T16, T16 and T84 recorded lower mean values than young dams; the trend was reversed for T21 only. There were no significant differences within treatment groups (irrespective of dam age) between the parities for T21, T16 and T16 while for treatment T84 the first parity had a higher value (P<0.05) than the second.

Effect of weaning age and parity on the mean daily weight gain (g) of kids

The mean daily weight gain for parities and dam ages was consistently lowest (P<0.05) for treatment T84 compared to the other treatment groups (Table 4). Also independent of parity higher mean values were obtained in the treatments where early weaning was practiced for both old and young dams. This difference was higher (P<0.05) for young dams of treatment T16 than T16, T84 and T21. Also, higher values were obtained for old dams in T16 and T16 while the reverse was true for T21 and T84. In this study an increase in average daily weight gain of 1.05 g as a result of early weaning of was recorded and corresponded to an increase in live weight of 66.1 g for guinea pigs raised over a growth period of 9 weeks after weaning.

The within treatment average daily weight gain values as reflected by parity did not show any definite pattern or significant differences (Table 4) irrespective of age of dam. However, consistently lower mean values were obtained with treatment T84 as opposed to the other treatments.

Influence of weaning and dam age on survival rates (%) of kids

As shown in Figure 1, the variation in survival rates (%) as reflected by dam age showed relatively higher mean values for old dams than young dams for treatment T21 (83.33 vs. 71.66) and T16 (85.71 vs. 79.16) while no difference was observed with treatment T16 (83.33 for both dams). Treatment T84 recorded a higher value for young dams (69.04) than old dams (56.25). The overall mean difference (irrespective of treatment) between old and young dams was 5.43 % in favour of old dams. When treatments were considered, the survival rate difference between early weaning treatments (T16 and T16) against weaning at 21 days (T21) and weaning at 84 days (T84) was 29.46 % and 21.79 % respectively for both old and young dams with early weaning treatments having higher values.

Independent of age of dam and parity (Figure 1), the highest mean survival rate (%) was obtained with T21 (87.49). This was closely followed by the treatments with early weaning T16 (83.33) and T16 (82.43) while T84 recorded the lowest value (62.64). When the average of early weaning treatments (T16 and T16) was compared with that of later weaning treatments (T21 and T84), the difference obtained was 15.63 % in favour of early weaning.

Influence of weaning age on live weight changes

The evolution of live weights (Figure 2) for the respective treatments from weaning to 11-12 weeks age showed fastest live weight changes for treatment T16 followed by T16, T21 and T84. This could be observed when the mean differences between the weaning weight and the weight at 11-12 weeks for the respective treatments were compared. These mean values were 153.91, 153.75, 136.00 and 107.13 grams for T16, T16, T21 and T84 respectively. When early and later weaning were compared (T16 and T16 Vs T21 and T84), the mean difference between these values was 64.53 grams in favour of early weaning.

Influence of weaning age on litter size

There was a linear increase in the subsequent litter size of dams with a reduction in the weaning age up till weaning at 21 days of age. The highest mean litter size was recorded in T16 with a value of 1.4 ± 0.11 while the lowest was in T84 (1.1 ± 0.07). This gave a difference in the mean litter size of 0.3 between weaning at 11 days and weaning at 84 days. This represented the highest mean difference in litter size recorded in the study irrespective of treatment.

Discussion

Results for the weaning weights recorded for this study are lower than the range reported by Ngou Ngoupayou (1992) and Tchoumboue et al (2001) for guinea pigs under traditional management and guinea pigs fed legumes with rabbit feed as supplements respectively. They are however similar to the range reported by Manjeli et al (1998).

In this study, the earliest weaning treatment (T16) had significantly lower values for the weaning weights, due to the reduction in the weaning age by 10 days from weaning at 21 days of age (T21). This treatment (T16) also recorded the highest mean litter size 1.4 ± 0.11 as opposed to 1.1 ± 0.07 for treatments where weaning weights were measured 10 days later. The relationship between litter size and birth weight has been shown to be mutually exclusive in guinea pigs (Manjeli et al 1998). The results in this study obtained for average daily weight gains is a clear indication of the importance of early weaning to the growth performance of kids. The consistently lower values (independent of parity and age of dam) recorded for treatment T84 point to this fact. The observation was more evident from the average daily weight gains of kids for the early weaning treatments at 16 and 11 days. Early weaned kids overcome weaning stress and also develop the capacity to handle efficiently solid and fibrous food earlier in life than late weaned kids. This gave them an initial advantage in feed conversion efficiency, which was maintained throughout the growing period.

Although Piattoni et al (1999) and Xiccatto et al (2000) did not observe any significant influence of early weaning on the subsequent viability of rabbits, Fortun-Lamothe et al (2001) showed that early weaning provided higher viability and fastest growth in weaned rabbits. Gidenne and Fortun-Lamothe (2002) also reported that the composition of the diet given to young rabbits (18 - 30 days of age) influence the development of their digestive capacity, performance and later viability. They further stressed that although the development of the digestive capacity of the young rabbit is essentially under the control of ontogenetic factors, the nutritional composition of the diet consumed around weaning could affect the development of intestinal digestive capacities and more particularly microbial activity in the caecum. Diet composition in early weaning therefore influences digestion and growth performance.

The guinea pig being pseudo-ruminants with essentially the same digestive system and physiology like rabbits would have the same response. The variation in post weaning survival of kids observed in this study was about 16% higher for early weaning treatments (T16 and T16) than for later weaning (T21 and T84). This points to the increased ability of kids to survive the extra-maternal environment after weaning which is another advantage of early weaning. This too could be related to the composition of the diet of kids around weaning for kids weaned early in this study. The early-weaned kids were placed on supplements containing high fibre (75% wheat bran) which at the early age probably modified the digestive capacity and the microbial activity in the caecum. However, Gidenne and Fortun-Lamothe (2002) had observed that caecal fermentative parameters are indicators of the health status of animals and their susceptibility to infection. A good supply of fibre before and after weaning seemed to have a favourable effect on health status.

Although viability is not synonymous to survival, an animal with high viability would be more likely to feed well and survive than a weaker one. Mean values for the evolution of live weights for the respective treatments showed fastest live weight gains for weaning at 11 and 16 days in that order. Despite the fact that weaning stress brought about initial decreases in the growth rates for weaning at these ages (especially 11days) than weaning later, the drop was covered-up before 11-12 weeks of age.

Faster growth in early-weaned kids made them to cover-up for the drawback of weaning. Although the same drawback was inflicted on kids weaned at 21 days of age, the physiological changes that took place with early weaning might have exposed the early-weaned kids to a longer period of compensatory growth than those weaned later.

With rabbits Piattoni et al (1999) observed that weaning at 18 days of age (instead of normal weaning of 28-35 days of age) caused young rabbits to remain for 1-2 days without eating but their food consumption increased rapidly after the withdrawal. They also observed that at 32 days early-weaned rabbits were lighter than unweaned ones but the difference was no longer present at 50 days of age. Similar results have also been obtained for rabbits at 50 days of age by other authors (Xiccatto et al 2000 and Gidenne and Fortun-Lamothe 2001). Although the feed intake of guinea pigs were not determined for this study, these findings are similar to those recorded for rabbits.

Conclusion

• Since kids are the most vulnerable component of any flock, improvements that will bring about positive changes in the growth and survival of kids like early weaning is bound to increase productivity and economic returns.

• Early weaning strategies for guinea pig production especially at the farm level in Cameroon could bring interesting contributions to guinea pig productivity.

• Where efficient feeding strategies can be developed, weaning at 11 days will permit an increase in the overall productivity through higher performance in growth and survival of kids. This will contribute substantially to the animal protein intake of rural dwellers in Cameroon.

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