Biological defleecing: intravenous infusion of amino acid mixtures lacking lysine and methionine creates a weakened zone in the wool staple, which is amenable to mechanical wool harvesting
P. I. Hynd A C , N. M. Edwards A , S. Weaver A , K. Chenoweth A , R. Stobart B and N. Heberle AA School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, Roseworthy, SA 5371, Australia.
B Department of Animal Science, University of Wyoming, Laramie, Wyoming 82071, USA.
C Corresponding author. Email: philip.hynd@adelaide.edu.au
Animal Production Science 55(10) 1264-1271 https://doi.org/10.1071/AN14137
Submitted: 3 March 2014 Accepted: 12 August 2014 Published: 10 November 2014
Abstract
Conventional shearing of sheep is labour-intensive, expensive and presents significant occupational health and safety risks. The only alternative at present is based on injection of epidermal growth factor, which severs the fibre at the follicle level. This technology cannot be used in pregnant animals and requires application of a net to retain the severed fleece. An alternative is to create a weakened zone within the wool staple, which would be sufficiently strong to retain the fleece on the sheep while a protective covering regrows, but sufficiently weak as to allow painless and automated removal of the fleece. We demonstrate that this approach is possible using mixtures of amino acids lacking lysine and methionine. Initially we demonstrate the relationships between staple strength, a subjective ‘harvestability’ score and a subjective ‘pain’ score, using fleeces from animals treated with varying levels of cortisol to create a wide range of strengths of wool attachment. We assigned a score to the ease with which we could manually break the staples, and also to the animal’s response to breaking the staples still attached to the skin. The relationships between these variables indicated that a staple was considered harvestable and could be removed with minimal skin flinch response at a staple strength of ~10–13 N/kTex. Staples within this range were then produced by intravenous infusion of mixtures of amino acids lacking in lysine and methionine for a 5-day period. The weak point was uniformly created across the entire fleece and when a prototype roller-pin device was applied to the weakened wool, it uniformly broke the fleece of the three sheep tested. The mode of action of the amino acid treatment on wool growth was studied. There was no effect of unbalanced amino acids on the rate of follicle bulb cell division, the number of active wool follicles, or the length of the keratinisation zone in the wool follicle. Fibre diameter was reduced by ~4 microns by treatment, and intrinsic fibre strength (strength relative to cross-sectional area of the wool fibres), was reduced by ~50%. Results of these trials are encouraging but further work is required to develop a practical, on-farm method of altering systemic amino acid supply and to design an automated, high-throughput system of severing the weakened wool.
References
Ansari-Renani HR, Hynd PI (2001) Cortisol-induced follicle shutdown is related to staple strength in Merino sheep. Livestock Production Science 69, 279–289.| Cortisol-induced follicle shutdown is related to staple strength in Merino sheep.Crossref | GoogleScholarGoogle Scholar |
Auber L (1952) The anatomy of follicles producing wool fibres, with special reference to keratinisation. Transactions of the Royal Society of Edinburgh 62, 191–254.
| The anatomy of follicles producing wool fibres, with special reference to keratinisation.Crossref | GoogleScholarGoogle Scholar |
Hudson PRW (1979) Australian wool harvesting programme. In ‘Wool Harvesting Research and Development (proceedings of the first conference on wool harvesting research and development)’, 14–16 May 1979, Melbourne. (Ed. PRW Hudson) pp. 13–18.
Hynd PI, Everett BK (1990) Estimation of cell birth rate using colchicine metaphase arrest or DNA labelling with bromodeoxyuridine. Australian Journal of Agricultural Research 41, 741–749.
Hynd PI, Hughes A, Earl CR, Penno NM (1997) Seasonal changes in the morphology of wool follicles in Finewool and Strongwool Merino strains grazing at different stocking rates in southern Australia. Australian Journal of Agricultural Research 48, 1089–1097.
| Seasonal changes in the morphology of wool follicles in Finewool and Strongwool Merino strains grazing at different stocking rates in southern Australia.Crossref | GoogleScholarGoogle Scholar |
Maddocks IG, Jackson N (1988) ‘Structural studies of sheep, cattle and goat skin.’ (CSIRO Publishing: Melbourne)
Moore GP, Panaretto BA, Robertson D (1982) Inhibition of wool growth in merino sheep following administration of mouse epidermal growth factor and a derivative. Australian Journal of Biological Sciences 35, 163–172.
Reis PJ (1970) The influence of abomasal supplements of some amino acids and sulphur-containing compounds on wool growth rate. Australian Journal of Biological Sciences 23, 441–446.
Reis PJ, Colebrook WF (1972) The utilisation of abomasal supplements of proteins and amino acids by sheep with special reference to wool growth. Australian Journal of Biological Sciences 25, 1057–1071.
Reis PJ, Tunks DA (1978) The influence of abomasal supplements of zein and some amino acids on wool growth rate and plasma amino acids. Agric. Sci. Camb. 90, 173–183.
| The influence of abomasal supplements of zein and some amino acids on wool growth rate and plasma amino acids.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE1cXhtlGiuro%3D&md5=168df3d112669f4a25a5c872aebec488CAS |
Shi ZC, Devasagayaraj A, Gu K, Jin H, Marinella B, Samala L, Cott L, Stouch T, Tunoori A, Wang Y, Zang Y, Zhang C, Kimball SD, Main AJ, Sun W, Yang Q, Nouraldeen A, Yu XQ, Buxton E, Patel S, Nguyen N, Swaffield J, Powell DR, Wilson A, Liu Q (2008) Modulation of peripheral serotonin levels by novel tryptophan hydroxylase inhibitors for the potential treatment of functional gastrointestinal disorders. Journal of Medicinal Chemistry 51, 3684–3687.
| Modulation of peripheral serotonin levels by novel tryptophan hydroxylase inhibitors for the potential treatment of functional gastrointestinal disorders.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXnt1WitLw%3D&md5=8a46cb5fbde1f92b3629e451e99d86c5CAS | 18557609PubMed |
Venero J, Herrera A, Machado A, Cano J (1992) Changes neurotransmitter levels associated with the deficiency of some essential amino acids in the diet. The British Journal of Nutrition 68, 409–420.
| Changes neurotransmitter levels associated with the deficiency of some essential amino acids in the diet.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK38XlvFSku7c%3D&md5=12162f0d0c43b39b956daa3dc86e9946CAS | 1359904PubMed |
Yu Y, Song C, DiMaggio PA, Garcia BA, York A, Carey MF, Grunstein M (2012) Histone H3 lysine 56 methylation regulates DNA replication through its interaction with PCNA. Molecular Cell 46, 7–17.
| Histone H3 lysine 56 methylation regulates DNA replication through its interaction with PCNA.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38Xjt1yjurc%3D&md5=2f367aab591b210e3e29bc0baf794aecCAS | 22387026PubMed |
