Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-23T05:54:54.045Z Has data issue: false hasContentIssue false
  • English
  • Français

The effect of daylength on the growth of lambs 3. Level of feeding, age of lamb and speed of gut-fill response

Published online by Cambridge University Press:  02 September 2010

J. M. Forbes ,
Wendy B. Brown ,
A. G. M. Al-Banna  and
R. Jones
J. M. Forbes
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds, Leeds LS2 9JT
Wendy B. Brown
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds, Leeds LS2 9JT
A. G. M. Al-Banna
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds, Leeds LS2 9JT
R. Jones
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds, Leeds LS2 9JT
Get access

Abstract

Four experiments, each with 24 growing sheep, were carried out to investigate the effects of 8- or 16-h daylengths on growth and carcass characteristics. In the first two experiments, with 6- to 9-month-old castrated males, and 3- to 5-month-old female and castrated male animals, pair feeding of a concentrate feed was adopted. Live-weight gains were significantly greater under 16-h daylength, but carcass weights were not significantly increased because most of the live-weight difference was due to gut-fill. Carcass weights and measurements suggested that long daylength stimulated the growth of non-fat tissues at the expense of fat.

The third experiment compared castrated males fed either ad libitum or restricted to a daily ration proportional to each animal's own weight from 6 to 9 months of age. Food intake was higher in the ad libitum sheep but not significantly so. Weight gains were, however, significantly greater with ad libitum feeding and long daylength, compared with restricted feeding and short daylength, respectively. Gut-fill was greater in those kept in 16 h daylength and the small advantage in carcass weight was not significant. Carcass characteristics were not markedly affected by daylength, while carcass weight and fatness were higher following ad libitum feeding than restricted feeding.

In the fourth experiment 12 female sheep, aged 9 months, were individually rationed according to live weight and slaughtered after 4 weeks exposure to 16- or 8-h daylengths; another 12 were slaughtered after 7 weeks of treatment. Gut-fill was significantly greater in long daylength at both slaughter times, showing that the effect of daylength on gut fill has occurred within 4 weeks of the start of treatment, while live weight has not been observed to be affected at this stage in any experiment in this series.

Overall these experiments show little stimulating effect of long daylength on growth, and a large effect on gut-fill.

Type
Research Article
Information
Animal Production , Volume 32 , Issue 1 , February 1981 , pp. 23 - 28
Copyright
Copyright © British Society of Animal Science 1981

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.)

References

REFERENCES

Brown, Wendy B. and Forbes, J. M. 1980. Diurnal variations of plasma prolactin in growing sheep under two lighting regimes and the effect of pinealectomy. J. Endocr. 84: 91–99.CrossRefGoogle ScholarPubMed
Forbes, J. M., Driver, P. M., Brown, Wendy B., Scanes, C. G. and Hart, I. C. 1979b. The effect of daylength on the growth of lambs. 2. Blood concentrations of growth hormone, prolactin, insulin and thyroxine, and the effect of feeding. Anim. Prod. 29: 43–51.Google Scholar
Forbes, J. M., El Shahat, A. A., Jones, R., Duncan, J. G. S. and Boaz, T. G. 1979a. The effect of daylength on the growth of lambs. 1. Comparisons of sex, level of feeding, shearing and breed of sire. Anim. Prod. 29: 33–42.Google Scholar
Hàckett, M. R. and Hillers, J. K. 1979. Effects of artificial lighting on feeder lamb performance. J. Anim. Sci. 49: 1–4.Google Scholar
Nie, N. H., Hull, C. H., Jenkins, J. G., Steinbrenner, K. and Bent, D. A. 1975. Statistics Package for the Social Sciences. McGraw-Hill, New York.Google Scholar