A note on the effect of bovine somatotrophic hormone on wool production in growing lambs

Reklewska, B.

doi:10.1017/s0003356100022819

Cited by 14 publications

(7 citation statements)

References 3 publications

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“…Wool growth w".s significantly stimulated by daily GH injections (0·1 mg kg-1 liveweight) for a period of 12 weeks; this response was decreased by the simultaneous administration of bromocryptine. In contrast to the report of Reklewska (1974), these results could not be explained by an increase in feed intake in the GH-treated animals, although greater efficiency of feed conversion in GH-treated animals may in part account for the improved wool growth. The present results were derived from mature animals provided with a defined energy intake for an extended period to ensure stability of wool growth.…”

Section: Discussioncontrasting

confidence: 99%

“…Significant increases in clean wool weight in response to bovine GH injections (1 mg kg-1 every 10 or 15 days until weaning at 100 days) have been measured in growing lambs by Reklewska (1974), although this response may be explained by an increase in feed intake in the GH-treated animals. Nevertheless, the observation that feed intake remained stimulated for 15 weeks posttreatment suggested that GH had a persistent metabolic effect long after circulating GH concentrations had returned to basal levels, an effect which is consistent with the wool growth responses in the present study.…”

Section: Discussionmentioning

confidence: 99%

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Effects of Growth Hormone Administration on Wool Growth in Merino Sheep

Wynn

Wallace²,

Ac³

et al. 1988

Aust. Jnl. Of Bio. Sci.

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The effects of daily administration of 10 mg of highly purified ovine growth hormone (GH) for a period of 4 weeks on wool growth have been measured in 12 Merino ewes fed either a calculated maintenance energy intake or 1·6 times this amount (six on each ration). Concentrations of hormones, glucose, urea, a-amino N and amino acids in the blood were monitored and faeces and urine collected for measurement of nitrogen balance.Wool growth rate decreased by 200/0 during the 4 weeks of GH treatment in sheep fed the high energy diet, largely because of reduced wool fibre diameter. This was followed by restoration of normal growth and then an increase of up to 20% above control levels, a response which persisted for 12 weeks following cessation of GH administration, and which was due to increases in both fibre length and diameter. GH administration caused marked increases in plasma concentrations of GH, insulin and somatomedin C, glucose and free fatty acids, all of which returned to basal levels following cessation of GH administration. No consistent changes in plasma concentration of T 3 , T 4 , cortisol, prolactin or a amino N were detected. Plasma urea and methionine levels decreased during GH treatment and returned to, or were raised above, basal levels after the GH treatment period. GH injection also resulted in a net retention of N during treatment, followed by a transient period of net N loss.The GH-induced changes in wool growth may be caused by a change in the partitioning of amino acids between the muscle mass and the skin. No other contributing factor(s) were identified.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of Growth Hormone Administration on Wool Growth in Merino Sheep

Wynn

Wallace²,

Ac³

et al. 1988

Aust. Jnl. Of Bio. Sci.

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“…report a positive effect of somatotropin on growth in sheep. Subsequently, a number of studies reported similar effects (Wolfrom, Ivy and Baldwin, 1985;Heird, Hallford, Spoon, Holcombe, Pope, Olivares and Herring, 1988;Zainur, Tassell, Kellaway and Dodemaide, 1989) while others showed no effects of somatotropin on growth (Reklewska, 1974;Muir, Wien, Duquette, Ricks and Cordes, 1983).…”

Section: Introductionmentioning

confidence: 86%

“…Of the studies which have shown a significant effect, some observed an increase during the treatment period (Ferguson, 1954;Johnsson, Hart and Butler-Hogg, 1985;Johnsson, Ha thorn, Wilde, Treacher and ButlerHogg, 1987), some a decrease during treatment (Wheatley, Wallace and Bassett, 1966;Wynn, Wallace, Kirby and Annison, 1988) and others an increase after cessation of somatotropin treatment (Ferguson, 1954;Wheatley et al, 1966;Reklewska, 1974;Wynn et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

Wool follicle development, wool growth and body growth in lambs treated from birth with recombinantly derived bovine somatotropin

et al. 1992

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The effect of recombinantly derived bovine somatotropin (bST) administration on wool follicle populations, wool growth and body growth was examined in young lambs. Romney X (Border Leicester X Romney) lambs were treated with bST at doses of 0-1 or 0-3 mg/kg live weight per day, or with excipient, commencing on the day of birth and continuing at weekly intervals until the last injection was given at 11 weeks of age. Concentrations of immunoreactive somatotropin in plasma were 19-2 (s.e. 2-1), 65-2 (s.e. 2-8) and 74-7 (s.e. 4-8) \xgll in the control, low dose bST and high dose bST groups, respectively. Somatotropin treatment did not alter the density of primary (P) or secondary (S) follicles in the skin, or the S/P ratio, as measured by histological examination of mid-side skin biopsy samples at 14 weeks of age. Mid-side greasy and clean wool growth during weeks 2 to 14 of the study were increased (P < 0-05) in bST-treated lambs but treatment had no effect on wool growth during the immediate posttreatment period (iveeks 14 to 22), or on yearling fleece weight or wool quality characteristics. Body growth was not altered by bST administration. It is concluded that bST treatment stimulates wool growth even in very young lambs but, contrary to the results of a previous study, does not alter the development of wool follicle populations.

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“…Cependant, les premières expérimentations consacrées à l'étude des effets de la GH exogène sur la croissance se sont souvent soldées par des échecs chez le porc, le mouton et le bovin (Turman et Andrews, 1955 ;Henricson et Ullberg, 1960 ;Wheatley, 1966 ;Vézinhet, 1973 ;Reklewska, 1974 ;Muir et al, 1983 ;Brumby, 1959 ;Znidar, 1976 (Adam et al, 1985). Un bref résumé est repris ci-dessous.…”

Section: Introductionunclassified