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THE EFFECT OF DIFFERENT WEANING PRACTICES ON POST-WEANING GROWTH OF ANGORA KIDS

AND REPRODUCTION OF ANGORA EWES

 

J.H. Hoon#, W.J. Olivier & P.J. Griessel


Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg (EC), 5900

#E-mail: Jan Hoon

 


INTRODUCTION

Weaning is normally a stressful period in the young kid’s life and is often characterised by a decrease in weight gain, total cease in growth and in some cases even weight loss. This response is referred to as weaning shock. The level or degree of shock depends on age and weight of the kids, as well as the feeding program before weaning. From studies with both goats and sheep, it appears that body weight at weaning is normally more important than age when attempting to minimise weaning shock. Other factors influencing the effect of weaning shock on the growth of Angora kids are, amongst others, the general health of the kids, sex and other stress factors (O’Brien, 1998).

 

According to Van der Vyver (Personal communication, 2003) weaning shock and its subsequent negative effects, is one of the biggest problems in the Angora goat industry, if not the biggest. The weaned kid goes through a very critical growth stage from weaning (4-5 months of age) until it reaches the young goat stage (2-tooth). Terblanche (1991) indicated that a mortality rate of 12.5 % occurred in Angora kids from weaning until 2-tooth age, compared to only 3 % in Merino sheep. The artificial, early separation process between mother and kid is very drastic and, therefore, farmers try to wean their kids as late as possible. In practice, however, farmers also want the mating season to start as early as possible since the perception exists that the earlier the kid is born, the healthier and stronger it will be. It means that kids cannot be weaned later than February, because the ewe needs a resting period of at least three to four weeks before the start of the next mating season. Some farmers use different practical methods in an effort to limit the large negative effect of weaning shock on the post-weaning growth of the kids. One of these methods is to keep the kids with the ewes (no weaning) and to mate the ewes while their kids stay with them. Another method is to take the mothers away, but to replace them with other mature animals (dry ewes, kapaters, etc); the kids stay in a known environment and are accompanied by mature leader animals. Other practices, where the young are not weaned but are fitted with nose rings to prevent them from suckling, are occasionally used by cattle and sheep farmers and could also be used by Angora goat farmers.

 

Under penned conditions at Grootfontein, King et al. (1991) reported no significant differences in the average daily gain (ADG) of weaned and unweaned kids from four to seven months of age (Year 1: 21.9 ± 6.3 g vs 33.8 ± 6.4 g; Year 2: 9.0 ± 6.6 g vs 17.7 ± 6.7 g). In Year 2 the animals received a poorer diet (100 % lucerne hay) than in Year 1 (80 % milled lucerne hay, 20 % maize meal). Under good veld conditions at Jansenville, ADG of kids staying with their mothers (unweaned) was significantly higher (33.9 g) than weaned kids (10.2 g) and kids staying with other mature animals after weaning (12.4 g). Differences in the growth rate of male and female kids were also observed. Unweaned ram and ewe kids did not differ from each other, but the ADG of male kids that were weaned or swopped were significantly higher than the corresponding female kids. Under penned conditions the differences between the sexes were smaller, probably owing to better nutritional conditions (King et al., 1991). These results are contrary to reports by O’Brien (1998), indicating that male kids are more susceptible to weaning shock than females. 

 

The aim of the project was to find practical solutions for the problems generally experienced by Angora goats during the post-weaning period. The objectives of the project were therefore to determine the effect of different weaning practices on the post-weaning growth of kids, the body weight change of ewes from weaning until mating/scanning, the milk production of the ewes and the conception rate of ewes in the next breeding season.

 

MATERIAL AND METHODS

The project started on a farm in the Middelburg, Eastern Cape, district during the 2003/2004 kidding season. It was repeated at the same locality during the 2004/2005, 2005/2006 and the 2006/2007 kidding seasons. The farmer’s own animals were used and the animals grazed on natural veld. At the onset of the project, a flock of Angora ewes and their kids were randomly tagged with three different colour ear tags and numbered individually at the start of the kidding season in August 2003. In the following years, the nucleus of ewes in each group consisted of ewes that were also used in the project during the previous kidding season. Since ewes were culled from the flock as a normal management practice, replacement ewes were added randomly to the nucleus. The replacement ewes, as well as the kids of all the ewes, were randomly tagged with three different colour ear tags and numbered individually at the onset of kidding in each year.

 

At the time of weaning each year (January/February), the three treatments commenced as follow: Weaned – Kids and ewes were separated, i.e. normal weaning took place; Swopped – Kids were separated from their mothers, but were put with other mature ewes, i.e. normal weaning, but weaned kids stayed with other ewes; Not weaned – Kids and ewes remained together, i.e. no weaning took place.

 

In the 2004/2005 kidding season, ten ewes from each group that kidded in the same week and had single kids, were identified and marked. Milk production of these 30 ewes was recorded on a weekly basis from 3 weeks until six weeks after kidding and on a two-weekly basis thereafter until the next mating season started (Week 28). The oxytocin method was used to determine the 4-hour milk production of the 10 ewes in each group (Bencini, 1995).

 

Body weights of all the ewes were recorded at weaning and at mating/scanning. Body weights of the kids of all three groups were recorded at weaning and on a monthly basis up until the age of 10 months. The conception and scanning percentages of all the ewes of the three groups were determined by means of ultrasound scanning. The hair production of the individual kids was recorded at second shearing (± 12-month age) in 2005, 2006 and 2007. All the animals stayed in their respective groups until the final body weights of kids were recorded at 10-month age. The animals were subjected to the same management practices throughout the experimental period. Statistical analysis was done by using the Proc GLM procedures of SAS (Littell et al., 2002).

 

RESULTS AND DISCUSSION

The average milk production of the 30 ewes in the 2004/2005 kidding season over their lactation period until weaning, as well as the milk production of the 10 ewes per treatment from weaning until mating, are presented in Table 1 and Figure 1.

 

Table 1. Average milk production (± s.e.) of the ewes over their lactation period

 

Milk production of 30 ewes (ml/4 hours)

3

174 ± 41

4

211 ± 29

5

197 ± 21

6

242 ± 28

8

109 ± 11

10

93 ± 12

12

71 ± 9

14

71 ± 11

16

71 ± 10

18

65 ± 9

20

71 ± 11

22 (Weaning)

41 ± 7

 

Milk production of 10 ewes/group (ml/4 hours)

 

Weaned

Swopped

Not weaned

26

0 ± 10

56 ± 10

45 ± 11

28

0 ± 5

7 ± 5

19 ± 5


Figure 1. Milk production of ewes over their lactation period

 

The data from Table 1 and Figure 1 showed that the ewes reached their peak milk production at 4-6 weeks after lambing. At the commencement of the different treatments at weaning (Week 22), the milk production of all the ewes of the Weaned group dropped to zero during the following four weeks. However, the ewes of the other two treatments continued to produce milk, although the amounts were small.

 

The body weights, body weight changes (BWC) and average daily gain (ADG) of the kids from weaning until approximately 10 months of age for the four year period, are presented in Table 2 and Figure 2.

 

Table 2. Body weights and ADG (± s.e.) of kids of the different groups after weaning for the four year period

 

Weaned

Swopped

Not weaned

Weaning (kg)

17.93 ± 0.16

17.90 ± 0.18

17.92 ± 0.22

7-month age (kg)

18.26 ± 0.11a

17.96 ± 0.13a

17.52 ± 0.17b

8-month age (kg)

20.78 ± 0.11a

20.10 ± 0.13b

20.36 ± 0.15b

9-month age (kg)

20.33 ± 0.12

20.17 ± 0.13

20.19 ± 0.16

10-month age (kg)

20.60 ± 0.12a

19.79 ± 0.14b

20.27 ± 0.16a

Body weight change (kg)

2.64 ± 0.13a

1.82 ± 0.15b

2.31 ± 0.18a

ADG (g)

19.5 ± 0.9a

13.7 ± 1.1b

17.0 ± 1.3a

ab Values with different superscripts in rows, differ significantly (P<0.05)

 

Figure 2. Body weights of kids of the different groups after weaning for the four year period

 The combined data of the kids for the four year period showed that the BWC and ADG of the kids of the Weaned group did not differ (P>0.05) from the Not weaned group, but both were higher (P<0.05) than the kids of the Swopped group. The combined data also indicated a decline in growth rate of kids after eight months of age, coinciding with the start of the dry, winter period and subsequent deterioration in grazing conditions.

 

The body weights, body weight changes (BWC) and average daily gain (ADG) of the ram and ewe kids respectively, from weaning until approximately 10 months of age for the four year period, are presented in Table 3.

 

Table 3. Body weights and ADG (± s.e.) of the ram and ewe kids of the different groups after weaning for the four year period

 

 

Rams

Ewes

Weaned

Swopped

Not weaned

Weaned

Swopped

Not weaned

Weaning (kg)

18.51

± 0.21

18.57

± 0.25

18.72

± 0.30

17.17

± 0.16

17.18

± 0.26

17.31

± 0.30

7-month age (kg)

18.40

± 0.14a

18.18

± 0.18ab

17.68

± 0.23b

18.14

± 0.16 a

17.84

± 0.23ab

17.52

± 0.23b

8-month age (kg)

20.86

± 0.14a

20.38

± 0.17 b

20.56

± 0.21ab

20.81

± 0.16a

19.97

± 0.18b

20.54

± 0.20a

9-month age (kg)

20.55

± 0.15

20.43

± 0.18

20.43

± 0.22

20.16

± 0.17

19.98

± 0.19

20.32

± 0.21

10-month age (kg)

20.84

± 0.15a

20.12

± 0.19b

20.35

± 0.24ab

20.40

± 0.15a

19.50

± 0.19b

20.48

± 0.24a

Body weight change (kg)

2.66

± 0.16a

1.91

± 0.20b

2.07

± 0.26a

2.61

± 0.18a

1.68

± 0.21b

2.65

± 0.25a

ADG (g)

19.7

± 1.2a

14.4

± 1.4b

15.4

± 1.8b

19.3

± 1.3a

12.6

± 0.15 b

19.4

± 1.8a

ADG (g)

16.5 ± 0.9

17.1 ± 0.9

ab Values with different superscripts in rows, within sex, differ significantly (P<0.05)

 

The BWC of the ram and ewe lambs of the Weaned and Not weaned groups were higher (P<0.05) than the respective Swopped groups. The ADG of the ram lambs of the Weaned group were higher (P<0.05) than the other two groups, while the ADG of the ewe lambs of the Weaned and Not weaned groups were higher (P<0.05) than the Swopped group. However, the overall ADG of the ram and ewe lambs did not differ (P>0.05).

 

At weaning, the body weights of the ram kids of all three groups were higher (P<0.05) than the ewe kids. No differences (P>0.05) in BWC and ADG were observed between the ram and ewe kids within treatments over the four year period. These results do not concur with the reports of King et al. (1991) and O’Brien (1998), which indicated differences in ADG between ram and ewe lambs after normal weaning took place. 

 

The body weight of the ewes at weaning and mating and the BWC over the three year period are presented in Table 4, while the body weight of the ewes at weaning and scanning and the BWC in 2006/2007, are presented in Table 5.

 

Table 4. Body weights and BWC (± s.e.) of ewes of the different groups for the three year period

 

Weaned

 Swopped

Not weaned

Weight at weaning (kg)

29.21 ± 0.26a

31.62 ± 0.27b

31.40 ± 0.27b

Weight at mating (kg)

31.63 ± 0.27a

33.57 ± 0.28b

33.18 ± 0.28b

Body weight change (kg)

2.40 ± 0.14a

1.81 ± 0.15b

1.73 ± 0.15b

ab Values with different superscripts in rows, differ significantly (P<0.05)

 

Table 5. Body weights and BWC (± s.e.) of ewes of the different groups for the 2006/2007 kidding season

 

 Weaned

Swopped

 Not weaned

Weight at weaning (kg)

34.78 ± 0.65

34.97 ± 0.80

36.04 ± 0.70

Weight at scanning (kg)

42.07 ± 0.64a

39.97 ± 0.79b

41.87 ± 0.69a

Body weight change (kg)

7.29 ± 0.36a

5.00 ± 0.45b

5.84 ± 0.39b

ab Values with different superscripts in rows, differ significantly (P<0.05)

 

The combined data for the three year period from 2003/2004 to 2005/2006 indicate that the body weight change of the ewes where kids were weaned (Weaned) , was higher (P<0.05) than for the other two groups. In 2006/2007, the body weight of the ewes at scanning was higher (P<0.05) for the ewes of Weaned group compared to the Swopped group, but did not differ (P>0.05) from the Not weaned group. The body weight change of the ewes of the Weaned group from weaning until scanning was also higher (P<0.05) than the other two groups.

 

The average conception and scanning percentages of the ewes of the different groups for the four year period, are presented in Table 6.

 

Table 6. The conception and scanning percentages of the ewes for the four year period

 

Treatment 1

(Weaned)

Treatment 2

(Swopped)

Treatment 3

(Not weaned)

Conception percentage (%)

87.2

92.2

92.9

Scanning percentage (%)

104.4

112.0

112.3

Conception % - number of ewes scanned pregnant per number of ewes mated

Scanning % - number of kids scanned per number of ewes mated

 

The average conception and scanning percentages over the four year period were in favour of the ewes of Treatment 2 (Swopped) and Treatment 3 (Not weaned), compared to the ewes of Treatment 1 (Weaned). Despite the variation in conception and scanning percentages of ewes observed over the four year period, it is clear that the non-weaning of kids did not have any negative effect on the reproductive rate of the ewes.

 

The average hair production of the kids at second shearing (±12 month age) for the three years (2005 to 2007), are presented in Table 7.

 

Table 7. The hair production (± s.e.) of the kids at second shearing for the three year period

 

Treatment 1

(Weaned)

Treatment 2

(Swopped)

Treatment 3

(Not weaned)

Hair production (kg)

1.20 ± 0.02a

1.27 ± 0.02b

1.23 ± 0.02ab

ab Values with different superscripts, differ significantly (P<0.05)

 

The differences in average hair production of kids at second shearing were relatively small, with a higher value (P<0.05) for Treatment 2 (Swopped) compared to Treatment 1 (Weaned). No differences (P>0.05) in hair production were, however, observed between Treatment 1 (Weaned) and Treatment 3 (Not weaned), as well as between Treatment 2 (Swopped) and Treatment 3 (Not weaned).

 

CONCLUSION

The body weight change (BWC) and average daily gain (ADG) of the kids from weaning until approximately 10 months of age did not differ between the weaned and the unweaned kids for the four year period from 2003/2004 to 2006/2007. Also, no differences in BWC and ADG between the ram and ewe kids within treatments were observed over the four year period. With regard to the body weight of the ewes, it is evident that the weaning of kids had a positive effect on body weight change from weaning until mating/scanning in all four years. Only small differences in the average hair production of kids at second shearing for the three year period from 2005 to 2007 were observed among the three groups. The most important result from this study is, however, that the non-weaning of kids did not have any negative effect on the reproduction rate of the ewes in any of the years. It is also noteworthy that none of the ewe kids staying with their mothers got pregnant during the mating period in any of the years.

 

ACKNOWLEDGEMENTS

The following institutions/persons are acknowledged for their contribution to the project:

 

REFERENCES

Bencini, R., 1995. Use of intra-muscular oxytocin injections to measure milk output in non-dairy sheep, and its effect on milk composition. Aust. J. Exp. Agric. 35, 663-565.

King, P.R., Olivier, J.J., & Wentzel D., 1991. The effect of weaning on the growth rate of Angora goats. The Angora Goat and Mohair Journal, September 1991, 37-41.

Littell, R.C., Freud, R.J. & Struop, W.W., 2002. SAS-system for linear models, 4th Ed. SAS Institute. Inc. Cary, N.C., USA.

O’Brien, A., 1998. Nutrition of the young goat: birth to breeding. Ontario Ministry of Agriculture and Food, Canada.

Terblance, E le F., 1991. An investigation into Angora goat farming in South Africa (Part 6).  The Angora Goat and Mohair Journal, September 1991, 47-49. 

 

Published

Grootfontein Agric 8 (1)