Hostname: page-component-cd9895bd7-gxg78 Total loading time: 0 Render date: 2024-12-27T11:49:10.821Z Has data issue: false hasContentIssue false
  • English
  • Français

Genetic relationships between seasonal tissue levels in Scottish Blackface ewes and lamb growth traits

Published online by Cambridge University Press:  09 March 2007

N. R. Lambe ,
S. Brotherstone ,
M. J. Young ,
J. Conington  and
G. Simm
N. R. Lambe*
Affiliation:
Sustainable Livestock Systems Group, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK
S. Brotherstone
Affiliation:
Sustainable Livestock Systems Group, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK
M. J. Young
Affiliation:
Sustainable Livestock Systems Group, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK
J. Conington
Affiliation:
Sustainable Livestock Systems Group, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK
G. Simm
Affiliation:
Sustainable Livestock Systems Group, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK
*
†E-mail: Nicola.Lambe@sac.ac.uk
Get access

Abstract

Scottish Blackface ewes (no. = 308) were scanned four times per year using X-ray computed tomography (CT scanning) (pre-mating, pre-lambing, mid lactation and weaning), from 18 months to 5 years of age, giving a maximum of 16 scanning events per ewe. Total weights of carcass fat, internal fat and carcass muscle were estimated from the CT images at each scanning event. Lambs produced by these ewes were weighed at birth, mid lactation and weaning to calculate litter growth traits: litter birth weight; litter weight gain from birth until mid lactation; and litter weight gain from birth until weaning. Genetic (rg) and phenotypic (rp) correlations were estimated between ewe CT tissue traits and litter growth traits. Correlations between ewe CT tissue traits and litter size (LS) were also estimated. Ewe CT tissue traits were either unadjusted or adjusted for total soft tissue weight (sum of weights of carcass fat, internal fat and carcass muscle) to investigate relationships with either absolute tissue weights of carcass fat (CFWT), internal fat (IFWT), and carcass muscle (CMWT), or relative proportions of carcass fat (CFP), internal fat (IFP), and carcass muscle (CMP). Litter growth traits were either unadjusted or adjusted for litter size, to investigate relationships with total lamb burden (total litter birth weight (TBW), total litter weight gain from birth until mid lactation (TWGM), total litter weight gain from birth until weaning (TWGW)) or average lamb performance (average lamb birth weight (ABW), average lamb weight gain from birth until mid lactation (AWGM), average lamb weight gain from birth until weaning (AWGW)).

Moderate to large positive genetic correlations were estimated between absolute weights of all three ewe tissues (CFWT, IFWT, CMWT), or muscle proportion (CMP), and litter size (LS). Significant positive genetic correlations were also estimated between weight (CMWT) or proportion (CMP) of muscle carried by the ewe pre-mating and total birth weight (TBW) and weight gains (TWGM, TWGW) of her litter, largely due to the associated increase in litter size. Muscle proportion (CMP) was not significantly correlated to average lamb weights or weight gains (ABW, AWGM, AWGW). Pre-lambing carcass fat weight (CFWT) and proportion (CFP) in the ewe showed positive genetic correlations with average lamb weights and weight gains (ABW, AWGM, AWGW), whereas, after lambing, CFP was negatively correlated with these lamb traits. Internal fat weight (IFWT) pre-mating showed positive genetic correlations with all litter growth traits (TBW, TWGM, TWGW, ABW, AWGM, AWGW). Average lamb growth traits were negatively correlated with pre-lambing internal fat proportion (IFP), but positively correlated to IFP at mid lactation and weaning.

Correlations were also estimated between each pair of CT traits. Total internal fat weight and total carcass fat weight were very highly correlated (rp = 0·75, rg = 0·96). Correlations with total carcass muscle weight were smaller and positive for both carcass fat weight (rp = 0·48, rg = 0·12) and internal fat weight (rp = 0·42, rg = 0·20).

The results suggest that selection for increased carcass muscle weight or proportion in a Scottish Blackface hill flock would have a positive effect on total weights of litters reared, but that selection against carcass fat weight or proportion in a breeding programme for Blackface sheep may have an impact on the maternal ability of the ewe. However, maintaining fat in internal depots may reduce the depletion of carcass fat during pregnancy, allowing this depot to provide energy for lactation, and may have a positive impact on lamb growth.

Keywords

body compositioncomputed tomographyewesgenetic parametersregression analysis
Type
Research Article
Information
Animal Science , Volume 81 , Issue 1 , August 2005 , pp. 11 - 21
Copyright
Copyright © British Society of Animal Science 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

‡Sheep Improvement Ltd, PO Box 66, Lincoln University, Canterbury, New Zealand

References

Bunger, L., Lewis, R. M., Rothschild, M. F., Blasco, A., Renne, U. and Simm, G. 2005. Relationships between quantitative and reproductive fitness traits in animals. Philosophical Transactions of The Royal Society of London, Series B-Biological Sciences In press.CrossRefGoogle Scholar
Coffey, M. P., Emmans, G. C. and Brotherstone, S. 2001. Genetic evaluation of dairy bulls for energy balance traits using random regression. Animal Science 73: 29–40.CrossRefGoogle Scholar
Conington, J., Bishop, S. C., Grundy, B., Waterhouse, A. and Simm, G. 2001. Multi-trait selection indexes for sustainable UK hill sheep production. Animal Science 73: 413–423.CrossRefGoogle Scholar
Conington, J., Bishop, S. C., Waterhouse, A. and Simm, G. 1995. A genetic analysis of early growth and ultrasonic measurements in hill sheep. Animal Science 61: 85–93.CrossRefGoogle Scholar
Conington, J. and Hernando, A. 2000. Genetic analyses of fat, muscle, live weight and condition score. SAC/Roslin Institute hill sheep project, progress report, no. 15, pp. 16–21.Google Scholar
Cowan, R. T., Robinson, J. J., McDonald, I. and Smart, R. 1980. Effects of body fatness at lambing and diet in lactation on body tissue loss, feed intake and milk yield of ewes in early lactation. Journal of Agricultural Science, Cambridge 95: 497–514.CrossRefGoogle Scholar
Frutos, P., Mantecón, A. R. and Giráldez, F. J. 1997. Relationship of body condition score and live weight with body composition in mature Churra ewes. Animal Science 64: 447–452.CrossRefGoogle Scholar
Gibb, M. J. and Treacher, T. T. 1980. The effect of ewe body condition at lambing on the performance of ewes and their lambs at pasture. Journal of Agricultural Science, Cambridge 95: 631–640.Google Scholar
Gilmour, A. R., Cullis, B. R., Welham, S. J. and Thompson, R. 2001. ASREML reference manual. NSW Agriculture, Orange, NSW, Australia.Google Scholar
Gunn, R. G. and Doney, J. M. 1975. The interaction of nutrition and body composition at mating on ovulation rate and early embryo mortality in Scottish Blackface ewes. Journal of Agricultural Science, Cambridge 85: 465–470.Google Scholar
Lambe, N. R., Brotherstone, S., Lewis, R. M., Young, M. J., Conington, J. and Simm, G. 2002. A genetic analysis of seasonal tissue changes in Scottish Blackface ewes, using X-ray computed tomography. Proceedings of the seventh world congress on genetics applied to livestock production, Montpellier, vol. 29, pp. 593–596.Google Scholar
Lambe, N. R., Simm, G., Young, M. J., Conington, J. and Brotherstone, S. 2004. Seasonal changes in tissue weights in Scottish Blackface ewes over multiple production cycles. Animal Science 79: 373–385.Google Scholar
Lambe, N. R., Young, M. J., Brotherstone, S., Kvame, T., Conington, J., Kolstad, K. and Simm, G. 2003a. Body composition changes in Scottish Blackface ewes during one annual production cycle. Animal Science 76: 211–219.Google Scholar
Lambe, N. R., Young, M. J., McLean, K. A., Conington, J. and Simm, G. 2003b. Prediction of total body tissue weights in Scottish Blackface ewes using computed tomography scanning. Animal Science 76: 191–197.CrossRefGoogle Scholar
McClelland, T. H. and Russel, A. J. F. 1972. The distribution of body fat in Scottish Blackface and Finnish Landrace lambs. Animal Production 15: 301–306.Google Scholar
Meat and Livestock Commission. 1988. Sheep in Britain. Sheep Improvement Services, Milton Keynes.Google Scholar
Peart, J. N. 1968. Some effects of live weight and body condition on the milk production of Blackface ewes. Journal of Agricultural Science, Cambridge 70: 331–338.Google Scholar
Peart, J. N. 1970. The influence of live weight and body condition on the subsequent milk production of Blackface ewes following a period of under nourishment in early lactation. Journal of Agricultural Science, Cambridge 75: 459–469.Google Scholar
Russel, A. J. F., Gunn, R. G. and Doney, J. M. 1968. Components of weight loss in pregnant hill ewes during winter. Animal Production 10: 41–53.Google Scholar
Simm, G. and Dingwall, W. S. 1989. Selection indices for lean meat production in sheep. Livestock Production Science 21: 223–233.CrossRefGoogle Scholar
Taylor, St C. S. and Murray, J. I. 1991. Effect of feeding level, breed and milking potential on body tissues and organs of mature, non-lactating cows. Animal Production 53: 27–38.Google Scholar
Wood, J. D., MacFie, H. J. H., Pomeroy, R. W. and Twinn, D. J. 1980. Carcass composition in four sheep breeds: the importance of type of breed and stage of maturity. Animal Production 30: 135–152.Google Scholar