Phenotypic and genetic parameters for production characters of Cashmere goats in south west Queensland.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 19 PHENOTYPIC AND GENETIC PARAMETERS FOR PRODUCTION CHARACTERS OF CASHMERE GOATS IN SOUTH WEST QUEENSLAND MARY ROSEA, R. A. YOUNGA and S. J. EADY B *Animal Research Institute, Yeerongpilly, Qld 4 105. BFormerly Dept of Primary Industries, Charleville, Qld 4470. SUMMARY Phenotypic and genetic parameters and the effects of sex, year of measurement and birth type are presented for fleece characters and liveweight of lo-month-old Cashmere goats. Bucks had heavier fleece weights and liveweights than does and higher yields but there was no difference in down diameter. Single-born goats had heavier fleece weights and liveweights. Year of measurement had a significant effect on most characters. Heritabilities for all characters were high. Phenotypic and genetic correlations were within the published range and confirm unfavourable genetic associations between down weight and diameter and between diameter and liveweight. Keywords: Cashmere goats, fleece characters, heritability, genetic correlations, phenotypic correlations. INTRODUCTION Accurate estimates of genetic and phenotypic parameters for production characters are intrinsic to the design of efficient breeding programs for Cashmere goats, as is a knowledge of the effects of environmental factors on these characters in the accurate selection of animals based on measurement. Pattie et al. (1990) have recently provided a review of the published estimates both for Australian and New Zealand goats. These data showed that there was considerable genetic variation between animals for Cashmere production, that most characters were moderately to highly heritable but that there existed a number of unfavourable genetic relationships between production characters. Rose et al. (1991) have also reviewed the current recommendations for breeding programs based on existing knowledge of these estimates. In this paper we report the results of a study of a small breeding herd in southern Queensland which includes the effects of sex, year of measurement and birth type on fleece production characters and liveweight at 10 months of age and estimates of genetic and phenotypic parameters for these characters. MATERIAL AND METHODS The animals, the location and management of the herd and the measurements made on the animals have been described in detail by Eady and Rose (1988) and Eady et al. (1988). The entire flock was removed from Charleville to Hermitage Research Station at Warwick in March 1990 so both does and bucks from the 1989 drop were measured in July 1990 at Warwick. Data presented are the combined production of 2 shearings; at 6 months and at 10 months. Complete records of greasy fleece weight (GFW), percentage yield of down (YLD), down weight (DWT), down diameter (DIAM) and liveweight (LWT) were available for 487 lo-month-old goats from 4 drops (1986-1989), the progeny of 18 sires and 235 dams. Two sires were used in 3 years, 4 in 2 years and 12 in only one year. There were 259 males and 228 females. There were 103 animals born as singles and 384 born in multiple births. Measurements for 205 progeny were available in 1987, 71 in 1988, 118 in' 1989 and 93 in 1990. These data were analysed using the model: Y where Yij,, = the individual measurement; p = population mean; Si = the random effect of sirei; Gj = fixed effect of sexy; Tk = the fixed effect of year of measurementk; Br the fixed effect of the birthtypel; eijkhn = randomerror. Analyses were carried out using the program LSMLMW (Harvey 1987). RESULTS AND DISCUSSION Effects of environmental factors Table 1 shows the least squares means for fleece characters and liveweight for each of the environmental factors. Bucks were heavier and had heavier fleece weights than does and the yield of down was lower in does. However the down diameter was sirnilar for males and females. Gifford et al. (1990) reported similar effects for sex although yield was lower for males than females in their herd. 266 Proc. Aust. Sot. Anim. Prod. Vol. 19 Table 1. Least-squares means for fleece characters [greasy fleece weight (GFW), yield of down (YLD), down weight (DWT), down diameter (DIAM)] and for liveweight (LWT) of lo-month Cashmere goat progeny For each character, means followed by different letters differ significantly (P c 0.05) Birth type had a significant effect on both fleece weight and liveweight but not on yield, down weight or diameter. Goats born as singles had heavier fleeces and had heavier liveweights. These effects were similar to those of Gifford et al. (1990) for greasy fleece weight, yield and liveweight but they reported differences due to birth type for both down weight and diameter; the singles having higher down weights and coarser down. Year of measurement had a significant effect on greasy fleece weight, down weight, diameter and liveweight. This was especially so for 1990 measurements when the comparison is confounded by a change of environment for does compared with other years. Couchman and Wilkinson (1988) found no such effect. It would seem appropriate to investigate environmental effects and correct for any factor which is significant before using measurements at 10 months as the basis of selection. Phenotypic and genetic parameters Table 2 shows the least-squares means for each of the production characters and the genetic and phenotypic parameters for each production character Table 2. Phenotypic and genetic parameters for fleece characters [greasy fleece weight (GFW), yield of down (YLD), down weight (DWT), down diameter (DIAM)] and for liveweight (LWT) of lo-month Cashmere goat progeny Standard errors of estimates appear in brackets below the estimates. Phenotypic correlations are above the diagonal and genetic correlations below Proc. Aust. Sot. Anim. Prod. Vol. 19 Compared with herds reported by Couchman and Wilkinson (1988) in Victoria and Gifford et al. (1990) in South Australia for goats of similar age, these goats have higher fleece weights, lower yields and coarser down diameter. Down weights are similar to the Victorian herd but higher than the South Australian goats. These differences are however phenotypic and may not necessarily reflect genetic differences.Heritability estimates ranged from 0.33 for liveweight to 0.67 for greasy fleece weight; all characters were highly heritable. The heritability of liveweight, greasy fleece weight and down weight were higher than published estimates, for down diameter it was lower and for yield in the middle of the published range (Pattie et al. 1990). These estimates would confirm that breeding programs based on mass selection for these production characters are likely to produce good responses. The phenotypic correlations between most characters are moderate although there is no correlation between down weight and liveweight. These estimates are generally within the range of those published (Pattie et al. 1990). This means that selection of goats with higher fleece weights than the mean would give animals which also have heavier down weights, coarser diameters and higher liveweights. All estimates of genetic correlations were within the published range (Pattie et al. 1990) except those for liveweight with other production characters which were all positive and very much higher than other published ones. However in all cases they were associated with very high standard errors. Conclusions The unfavourable associations between down weight and diameter and between liveweight and diameter described by Pattie and Restall (1989) and Gifford et aZ. (1990) are again found here. As has been described previously by these and other authors, the use of appropriate selection indices can allow genetic improvement of down weight, diameter and liveweight within a breeding program (Rose et al. 1991). COUCHMAN, R. C. and WILKINSON, J .L. (1988). Proc. Aust. Assoc. Anim. Breed. Genet. 7: 5 17-20. ROURKE, P K. and ROSE, MARY (1988). Proc. Aust. Assoc. Anim. Breed. Genet. 7: 521-4. EADY, S. J., O' EADY, S. J. and ROSE, MARY (1988). Proc. Aust. Sot. Anim. Prod. 17: 182-5. GIFFORD, D. R., PONZONI, R. W., ELLIS, N. J. S., LEVINGE, F. C. R. and MILNE, M. L. (1990). Proc. Aust. Assoc. Anim. Breed. Genet. 8: 461-5. HARVEY, WALTER R. (1987). User' guide for LSMLMW - mixed model, least-squares and maximum likelihood s program. Ohio State University: Columbus, OH. PATTIE, W. A., BAKER, R. L., NICOLL, G. B. and RESTALL, B. J. (1990). Proc. 4th World Congress on Genetics Applied to Livestock Production, Edinburgh, 23-27 July 1990. pp. 167-76. RESTALL, B. J. and PATTIE, W. A. (1989). Livest. Prod. Sci. 21: 157-72. ROSE, MARY, RESTALL, B. J. and PATTIE, W. A. (1991). Proc. Aust. Assoc. Anim. Breed. Genet. 9: 408-11. REFERENCES 268