Last update: February 5, 2014 09:55:50 AM E-mail Print

 

THE EFFECT OF PROTECTIVE COATS MADE FROM RIPSTOP ON HAIR QUALITY TRAITS OF ANGORA GOATS

 

M.A. Snyman#, M. van Heerden & B.N. Mokgwamme

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

#E-mail: Gretha Snyman

 

INTRODUCTION

High mortality rates of Angora goats during periodic cold climatic spells cause considerable annual monetary loss in the mohair industry. An estimated number of 60 000 to 70 000 goats died from exposure to cold conditions over a ten year period from 1997 to 2007. This implies a financial loss on producer level in terms of mohair production of R14 million, and a direct loss in terms of animals of R21 million. Angora goats are most susceptible to cold spells during the first few weeks after shearing.

Various measures are taken to prevent losses during cold spells. On request of the mohair industry, Grootfontein Agricultural Development Institute (GADI) investigated the suitability of coats as protection against adverse weather conditions (Snyman & Van Heerden, 2011a, 2011b). The durability of the coats that were used in that trial was evaluated in the Noorsveld in the Jansenville district (Veld Type 24; Acocks, 1988). The results indicated that the material used is not tough and durable enough to withstand the Noorsveld vegetation. Investigations by private farmers identified Ripstop as a possible alternative material. As Ripstop material is waterproof, a further trial to assess the rate of drying off after wetting, as well as the effect of wearing the coats for an extended period on hair quality traits was done. 

 

MATERIALS AND METHODS

Wetting trial: November 2012

The first round of the trial was conducted on 30 November 2012. Thirty Angora goats with three-and-a-half months’ hair growth were used. One group of 15 animals received protective coats made from Ripstop (Coats group), while 15 animals did not receive any protective covering. On the day of the trial, 10 of the Coats (Coats Wet) and 10 of the Control (Control Wet) group animals were thoroughly wetted by applying water with a sprinkler system to simulate rain. They received the equivalent of 20 mm of rain. The remaining goats in each group did not receive any rain treatment and were kept dry (Coats Dry and Control Dry groups).

Humidity and temperature of the fleece were determined with a humidity / temperature meter. Humidity of the fleece was determined before and directly after wetting, and thereafter at 60, 180, 300 and 420 minutes after wetting. It was originally planned that the goats should keep the coats on for a six week period to evaluate the effect on hair quality, but at the end of the day, the humidity of the fleeces was too high and the goats showed physical signs of heat stress, and the coats were therefore removed.

 

Wetting trial: April 2013

The same trial was repeated on 24 April 2013 on 30 seven-month-old Angora kids with three months’ hair growth. The same procedures were followed as described above. Humidity and temperature measurements were taken before wetting, directly after wetting and thereafter at 60, 120, 180, 300 and 420 minutes after wetting.

 

Wetting trial: August 2013

The same trial was repeated on 6 August 2013 with the 30 newly shorn Angora kids. The same procedures were followed as described above. Humidity and temperature measurements were taken before wetting, directly after wetting and thereafter at 60, 120, 180, 240 and 300 minutes after wetting.

 

Hair quality trial

The hair quality trial was done simultaneously with the humidity trial in April 2013 on the 30 seven-month-old Angora kids with three months’ hair growth. A midside fleece sample was taken for fibre diameter and clean yield analysis. Hair quality traits, as indicated in Table 1, were assessed on a linear scale from 1 to 50. Before shearing at six months’ hair growth, hair quality was again assessed and a midside fleece sample taken for fibre diameter and clean yield analysis. Fleece weight was recorded after shearing.

 

Table 1. Linear scale for the assessment of hair quality traits

Trait

Linear scale

1

25

50

Style

No style

Average style

Excellent style

Character

Straight

Ideal

Over-curly

Evenness of fleece

Much variation

Average

No variation

Yolk

Too little

Ideal

Too much yolk

 

RESULTS AND DISCUSSION

Wetting trials

The humidity of the fleeces recorded over the one-day trial periods during November 2012, April 2013 and August 2013 are presented in Figures 1 to 3 respectively. It is clear from Figures 1 and 2 that the fleece humidity of the Coats Wet animals did not increase after receiving the equivalent of 20 mm of rain. During the November trial (Figure 1), just after wetting at 0 minutes, the Control Wet group animals had the highest fleece humidity (89 %), followed by the Coats Dry (77%) and Control Dry (75%) groups. The Coats Wet group had the lowest fleece humidity of 63%. As ambient temperature increased from 0 to 60 minutes, the fleece humidity of Coats Wet animals increased to 82%. For the remainder of the trial period, fleece humidity of both the Coats Dry and Coats Wet animals remained at around 80%. The fleeces felt wet under the coats. After 60 minutes, fleece humidity of both the Control Dry and Control Wet animals decreased to about 50% at the end of the trial.

 

 

Figure 1. Humidity of the fleece of wetted and dry goats with or without Ripstop coats (November 2012)

 

Figure 2. Humidity of the fleece of wetted and dry goats with or without Ripstop coats (April 2013)

 

As was the case with the November trial, the fleece humidity of the Coats Wet animals during the April 2013 trial (Figure 2) did not increase after receiving the equivalent of 20 mm of rain, while fleece humidity of the Control Wet animals increased from 75% to 89%. Fleece humidity of the Coats Wet animals remained constant at around 72% for three hours, after which it decreased to reach the levels of the Coats Dry animals at the end of the trial period. These were, however, still 20% higher than that of both the Control groups.

 


Figure 3. Humidity of the fleece of wetted and dry goats with or without Ripstop coats (August 2013)

 

During the August 2013 trial (Figure 3), done with the newly shorn animals, fleece humidity of both the Control Wet as well as the Coats Wet animals increased after receiving 20 mm rain treatment. Humidity of the Control Wet animals increased by 64% to 95%, while that of the Coats Wet animals increased by 23% to 68%. Just after treatment, significant differences in humidity were recorded among all groups. Humidity of the Coats Wet animals decreased at a slower rate than that of the Control Wet animals. Both groups reached their approximate starting levels two hours after treatment. Humidity under the coats of newly shorn goats remained higher than for goats without coats, although this difference was smaller than for goats with three months’ hair growth.  

There were no significant differences in fleece temperature among the different groups over the November 2012 trial period. Temperature of the fleece of goats with or without Ripstop coats for the April 2013 trial is depicted in Figure 4. From this figure it is obvious that the fleece temperature of only the Control Wet group animals dropped after being wetted. However, it recovered to the values of the other groups after 60 minutes. Thereafter, no significant differences in temperature of the fleece were recorded among any of the groups. There were also no significant differences in fleece temperature recorded among the different groups for the August 2013 trial period.

 

 

Figure 4. Temperature of the fleece of wetted and dry goats with or without Ripstop coats (April 2013)

 

The coats were left on the goats after the April 2013 trial and humidity and temperature were recorded weekly for the next 14 weeks. The humidity and temperature of the fleeces recorded over this trial period are presented in Figures 5 and 6 respectively.

 

 

Figure 5. Weekly humidity of the fleece of goats with or without Ripstop coats (April to July 2013)

 

From Figure 5 it is evident that humidity of the fleece generally tends to follow ambient humidity. Fleece humidity of the Coats animals was higher than that of the Control animals, except during Week 10, when a drop in ambient humidity from the previous week was experienced. No significant differences in temperature of the fleece were recorded between the groups (Figure 6).

 


Figure 6. Weekly temperature of the fleece of goats with or without Ripstop coats (April to July 2013)

 

Hair quality trial

Hair quality traits and body weight of the animals before putting on the coats are presented in Table 2, while the same traits recorded after removal of the coats after a 14-week period are presented in Table 3.

 

Table 2. Body weight and hair quality traits of the different groups before putting on the coats

Trait

Coats

Control

Body weight (kg)

27.4 ± 0.9

26.6 ± 0.9

Style

24.5 ± 1.7

24.4 ± 1.7

Character

26.2 ± 1.2

24.7 ± 1.2

Evenness of fleece

36.2 ± 1.6

34.2 ± 1.6

Yolk

26.5 ± 1.0

26.0 ± 1.0

Clean yield percentage

79.3 ± 1.1

81.4 ± 1.1

Fibre diameter (µm)

25.5 ± 0.5

26.1 ± 0.5

Standard deviation of fibre diameter (µm)

6.5 ± 0.2

6.5 ± 0.2

Coefficient of variation of fibre diameter (%)

25.6 ± 0.7

24.9 ± 0.7

Comfort factor (%)

77.5 ± 2.3

75.0 ± 2.3

Standard deviation along the fibre (µm)

1.6 ± 0.2

1.4 ± 0.2

Staple length (mm)

54.0a ± 2.3

63.3a ± 2.3

a Values with the same superscripts differ (P<0.05) among groups within traits


Table 3. Body weight, fleece weight and hair quality traits of the different groups after removing the coats

Trait

Coats

Control

Body weight (kg)

36.3 ± 1.3

36.7 ± 1.2

Fleece weight (kg)

1.87 ± 0.09

2.00 ± 0.09

Style (After removal of coats)

10.0a ± 1.2

24.2a ± 1.2

Style (After dipping)

23.9 ± 1.2

25.5 ± 1.2

Character

29.9a ± 1.1

24.0a ± 1.1

Evenness of fleece

29.0a ± 1.0

33.1a ± 0.9

Yolk

28.9a ± 1.4

24.4a ± 1.3

Clean yield percentage

79.3 ± 1.0

78.5 ± 0.9

Fibre diameter (µm)

26.6 ± 0.5

27.8 ± 0.5

Standard deviation of fibre diameter (µm)

6.8 ± 0.2

6.9 ± 0.2

Coefficient of variation of fibre diameter (%)

25.7± 0.6

24.7 ± 0.6

Comfort factor (%)

72.6 ± 2.5

67.3 ± 2.4

Standard deviation along the fibre (µm)

1.8 ± 0.2

1.7 ± 0.2

Staple length (mm)

117.9a ± 3.9

130.0a ± 3.7

a Values with the same superscripts differ (P<0.05) among groups within traits

 

Fleeces of the goats that wore the coats for a 14-week period had poorer style, more character and more yolk than those of the Control group goats (Table 3). After dipping, some style returned to the fleeces of the Coats group goats (Figure 7). Similar results were obtained in the previous trial (Snyman & Van Heerden, 2011b), where goats that wore coats for a six-month period, had poorer style and more character than goats without coats.

In this trial, no difference in clean yield percentage was recorded, although on subjective assessment, fleeces of the coated animals appeared cleaner. In a study with Angora goats in Texas, Lupton et al. (2008), found that goats wearing coats produced fleeces with higher clean yields (74% versus 71%) compared to those from uncoated animals. Coats, however, did not affect any of the other measured hair quality traits in that study. Sheep coats also significantly reduced wool dust content, suint content and vegetable matter contamination of wool, leading to improved wool yields and improved style of the wool (Ford & Cottle, 1993; Davies et al., 1994; Crowe et al., 1996; Hatcher et al., 2003; Campbell & Schlink, 2007; Hatcher et al., 2008). A possible explanation for the result obtained in the current study is that the animals were kept in kraals for the entire trial period, which could have limited contamination of the fleece with plant material.

 

 It should be noted that the difference recorded in staple length is purely incidental, as the animals were divided into the groups on the basis of body weight.

 

 

Figure 7. Coats group goat (left) and just after removal of the coat (right)

 

 

Figure 8. Fleece of Coats group goat just after removal of the coat (left) and after dipping (right)

 

 

Figure 9. Fleece of Control group goat just after removal of the coat (left) and after dipping (right)


CONCLUSIONS

Results from the wetting trial indicate that the Ripstop coats are not suitable to wear during the hot summer months, as the animals sweat under the coats and showed signs of heat stress. During the winter months, it took between three and five hours for the fleece humidity of animals with three months’ hair growth with coats that received 20 mm rain to reach the same humidity level as coated goats that did not receive rain treatment. Humidity under the coats of newly shorn goats increased after wetting, but it decreased after about two hours to initial humidity levels. Overall, during the winter months fleece humidity under the coats is lower than recorded during the summer trial, but it still remains higher than that of goats without coats. 

Wearing the coats for an extended period had an effect on the appearance of the fleece, in terms of style and character. However, dipping the goats before shearing tended to restore some of the lost style. None of the fibre diameter traits were affected. Although the fleeces of the Coats group goats looked cleaner on subjective assessment, there was no difference in clean yield percentage between the groups in this trial. This could most probably be ascribed to the fact that the animals were kept in kraals for the entire trial period.

 

REFERENCES

Acocks, J.P.H., 1988. Veld types of South Africa. In: Memoirs of the botanical survey of South Africa No 57. 3rd edition. Botanical Research Institute, Dept. of Agric. and Water Supply, Pretoria, South Africa.

Campbell, I.R.D. & Schlink, A.C., 2007. Efficacy of sheep coats for part of the year in western Australian Merino flocks. Anim. Prod. Austr. 25, 29-32.

Crowe, D.W., Davies, G.P., Whiteley, K.J., Smith, L.J., Ma, H.Z. & Zheng, B.D., 1996. Performance of wool from rugged and unrugged sheep in north-west China. Wool Tech. Sheep Breed. 44, 17-28.

Davies, G.P., You, Z.F., Crowe, D.W., Whiteley, K.J., Ma, H.Z., Song, S.Z. & Mcguirk, B.J., 1994. Improvement of wool production and quality by the use of sheep rugs on Gansu Alpine Finewool sheep in north-west China. J. Agric. Sci. 123, 371-377.

Ford, K.L. & Cottle, D.J., 1993. A review of the use of sheep coats to improve the processing potential of wool. Wool Tech. Sheep Breed. 41, 161-172.

Hatcher, S., Atkins, K.D. & Thornberry, K.J., 2003. Sheep coats can economically improve the style of western fine wools. Aust. J. Exp. Agric. 43, 53-59.

Hatcher, S., Atkins, K.D. & Thornberry, K.J., 2008. Strategic use of sheep coats can improve your economic return. Aust. J. Exp. Agric. 48(7), 762-767.

Lupton, C.J., Huston, J.E., Hruska, J.W., Craddock, B.F., Pfeiffer, F.A. &  Polk, W.L., 2008. Comparison of three systems for concurrent production of high quality mohair and meat from Angora male kids. Small Rumin. Res. 74(1), 64-71.

Snyman, M.A. & Van Heerden, M., 2011a. Can protective coats alleviate the effect of cold, wet and windy conditions on Angora goats? Grootfontein Agric 11(2), 1-18.

Snyman, M.A. & Van Heerden, M., 2011b. Effect of protective coats on hair quality traits of Angora goats. Grootfontein Agric 11(2), 19-23.

 

 

Published

Grootfontein Agric 14 (1) (1)