The description and analysis of wool growth

Nagorcka, B.N.

doi:10.1071/ar9770737

Cited by 25 publications

(13 citation statements)

References 8 publications

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“…For example, results for SS are often confounded by pre-existing wool growth under different and usually undocumented conditions. Many investigations also fail to take into account the lag phase effects from previous management on wool attributes which take about 21 days to be overcome (Nagorcka, 1977).…”

Section: Experimental Approachesmentioning

confidence: 99%

On-farm factors affecting physical quality of Merino wool. 1. Nutrition, reproduction, health and management

McGregor

Graaf

Hatcher

2016

Small Ruminant Research

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Section: Experimental Approachesmentioning

confidence: 99%

On-farm factors affecting physical quality of Merino wool. 1. Nutrition, reproduction, health and management

McGregor

Graaf

Hatcher

2016

Small Ruminant Research

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“…Also there is an apparent 3! week lag between feed intake and wool growth (Nagorcka 1977). The process of regrowth involved the exfoliation of fibre remnants and epithelial debris from the upper parts of the follicles and restoration of normal follicle structure.…”

Section: Discussionmentioning

confidence: 99%

Effects of Zinc Deficiency on the Wool Growth, Skin and Wool Follicles of Pre-ruminant Lambs

Masters¹,

Chapman²,

Vaughan³

1985

Aust. Jnl. Of Bio. Sci.

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Two groups of I-month-old pre-ruminant lambs of similar mean liveweights were fed identical liquid milkreplacer diets except that the zinc contents were either 5 p.g (deficient diet) or 32 p.g per gram of dry matter (control diet). These diets were fed for 4 weeks, after which all the lambs received the control diet for 2 weeks.In the lambs fed the deficient diet plasma zinc concentration decreased markedly during the first 2 weeks and skin lesions developed around their mouths. Autophagic vacuoles also developed in most follicle bulbs along with a variety of defects in the wool fibres and progressive inhibition of wool growth. Food intake and liveweight increase were not significantly depressed until the third and fourth weeks of feeding the deficient diet. During this period the wool was shed from the zinc-deficient lambs as a result of the fibres being degraded and distorted within thickened outer root sheaths in the distal (upper) parts of the follicles. In addition, the epidermis of the wool-bearing skin became slightly acanthotic and hyperkeratotic, although not parakeratotic.When the deficient lambs were fed the control diet for 2 weeks, their food intake, liveweight gain and plasma zinc concentration increased to almost those of the control lambs, but their rate of wool growth was still low and the epidermis had not returned to normal. Compared with previous studies the findings of this study suggest that pre-ruminant lambs may be more susceptible to the effects of zinc deficiency than ruminant lambs.

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“…Sharkey et al (1962) and Sharkey and Hedding (1964) showed that liveweight relationships with wool growth were influenced by liveweight or liveweight change in the proceeding time periods due to delays in wool growth responses to changing nutrition. Nagorcka (1977), in an analysis of experimental estimates of wool growth, indicated a 3.5-week lag between changes in feed intake and wool growth. This lag appeared to be of similar order of magnitude to those reported for grazing experiments (Stewart et al 1961;Purser 1980;Revell et al 1994).…”

Section: Discussionmentioning

confidence: 98%

Seasonal variation in fibre diameter and length in wool of grazing Merino sheep with low or high staple strength

Schlink¹,

Mata²,

Lea³

et al. 1999

Aust. J. Exp. Agric.

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The associations between fibre growth characteristics and wool staple strength were investigated in groups (n = 10) of Merino wethers with either low or high staple strength. Sheep grazed together on pastures based on subterranean clover and annual rye grass for about 13 months. The sheep were weighed and injected intradermally with [35 S]-cysteine at about 14-day intervals. Mid-side patches were harvested and dye bands placed in the wool at about 28-day intervals. Patch clean wool growth, pasture digestible dry matter/ha and pasture crude protein/ha had similar seasonal amplitudes of production (287, 286 and 267% of respective minimum). These were significantly higher than the seasonal amplitude in liveweight (24.5%). The seasonal amplitude in fibre diameter was significantly greater than that for rate of fibre elongation (71.4 and 41.4% respectively). This seasonality in fibre length and diameter resulted in statistically significant seasonal fluctuations in the ratio of fibre length growth to fibre diameter. Fortnightly variability in fibre diameter was not significantly related to variability in fibre length growth rate between sheep for individual time periods. However, for the pooled data over the experimental period a statistically significant relationship (R2 = 0.13, P<0.01) was improved with the addition of parameters for sampling time and staple strength group. Staple strengths for the low and high staple strength groups were 25.6 and 32.8 N/ktex respectively (P = 0.057). There were no significant differences between the staple strength groups in seasonal change in liveweight, wool production or fibre parameters measured in this study but the low staple strength group had longer fibres. Staple strength was most highly correlated with mid-side fibre diameter coefficient of variation (R2 = 0.50) followed by seasonal amplitude in liveweight.

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The description and analysis of wool growth

Cited by 25 publications

References 8 publications

On-farm factors affecting physical quality of Merino wool. 1. Nutrition, reproduction, health and management

On-farm factors affecting physical quality of Merino wool. 1. Nutrition, reproduction, health and management

Effects of Zinc Deficiency on the Wool Growth, Skin and Wool Follicles of Pre-ruminant Lambs

Seasonal variation in fibre diameter and length in wool of grazing Merino sheep with low or high staple strength

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