Modeling the Productivity of a Breeding Sheep Flock for Different Production Systems

Title & Authors
Modeling the Productivity of a Breeding Sheep Flock for Different Production Systems

Abstract
Individual production traits, such as reproduction and mortality rates, are partial measures, but may be used to evaluate the performance of different systems by comparing the rate of flock growth and potential offtake. The productivity of two existing sheep production systems, one extensive, one intensive, was compared with an alternative semi-intensive system. The future flock sizes, offtakes and structures were predicted based on the age structure of the flock and age-specific reproduction, mortality and growth rates. The measurements were illustrated with reference to growth of a sheep flock of different age and sex categories. The flock was in a socalled dynamic situation. During the dry period, the digestible organic matter intake of the animals in the intensive system and both extensive and semi-extensive systems was 36 and 20.1 g kg$\small{^{-0.75}}$ d$\small{^{-1}}$, respectively. During the cold period, the digestible organic matter intake of the animals in extensive, intensive and semi-extensive systems was 34, 34.5 and 41 g kg$\small{^{-0.75}}$ d$\small{^{-1}}$, respectively. During the dry period, the animals in the both extensive and semi-intensive systems lost in body weight at a rate of 19 g per day, but the rate of gain in body weight of the animals in intensive system was 57 g per day. During the cold period, the animals in extensive, intensive and semiintensive systems gained in body weight at rates of 56, 67 and 97 g per day, respectively. The higher gain of animals during the cold period in the semi-intensive system was related to a sustained higher intake of low-quality roughage and more efficient use of the available feed. Compared to the intensive system, the annual concentrate input of the semi-intensive system was about 48% lower for each livestock unit. The productivity of the semi-intensive system was higher than that of the extensive system.
Keywords
Sheep;Model;System;Productivity;Growth;Seasonality;
Language
English
Cited by
1.
Effects of Restricted Feeding on Intake, Digestion, Nitrogen Balance and Metabolizable Energy in Small and Large Body Sized Sheep Breeds,;;

Asian-Australasian Journal of Animal Sciences, 2009. vol.22. 5, pp.667-673
References
1.
ARC. 1980. The Nutrient Requirements of Ruminant Livestock. Commonwealth Agricultural Bureaux, Farnham Royal, England.

2.
Akinsoyinu, A. O., A. U. Mba and F. O. Olubajo. 1977. Studies on milk yield and composition of the West African Dwarf goat in Nigeria. J. Dai. Res. 44:57-62.

3.
Bosman, H. G. 1995. Productivity assessments in small ruminant improvement programmes. A case study of the West African Dwarf Goat. PhD thesis, Wageningen Agricultural University, Wageningen, The Netherlands.

4.
Crow, J. F. 1986. Basic concepts in population, quantitative, and evolutionary genetics. W. H. Freeman and company, New York, pp. 11-17.

5.
Gingins, M., H. Bickel and A. Schurch. 1980. Efficiency of energy utilization in undernourished and realimented sheep. Livest. Prod. Sci. 7:645-671.

6.
Graham, N. McC. and T. W. Searle. 1979. Studies of weaned lambs before, during and after a period of weight loss. I. Energy utilization. Aust. J. Agric. Res. 30:513-523.

7.
Hogg, B. W. 1992. Compensatory growth in ruminants. In: Growth regulation in farm animals (Ed. A. M. Pearson and T. R. Dutson). Advances in Meat Research. Volume 7. London. UK. pp. 103-134.

8.
Kabbali, A., W. L. Johnson, D. W. Johonson, R. D. Goodrich and C. E. Allen. 1992. Effects of undernutrition and refeeding on weights of body parts and chemical components of growing Moroccan lambs. J. Anim. Sci. 70:2859-2865.

9.
Kamalzadeh, A., J. Van Bruchem, W. J. Koops, S. Tamminga and D. Zwart. 1997. Feed quality restriction and compensatory growth in growing sheep: feed intake, digestion, nitrogen balance and modelling changes in feed efficiency. Livest. Prod. Sci. 52:209-217.

10.
Knipscheer, H. C., U. Kusnadi and A. J. De Boer. 1984. Some efficiency measures for analysis of the productive potential of Indonesian goats. Agric. Syst. 15:125-135.

11.
Ledin, I. 1983. Effects of restricted feeding and realimentation on compensatory growth, carcass composition and organ growth in lambs. Swed. J. Agric. Sci. 13:175-187.

12.
Miao, Z. H., P. C. Glatz and Y. J. Ru. 2004. Review of production, husbandry and sustainability of free-range pig production systems. Asian-Aust. J. Anim. Sci. 17(11):1615-1634.

13.
Monem, M. 1984. Iranian sheep breeds (Persian). Research publication 47. Animal Husbandry Research Centre, Karaj, Iran. pp. 36-51.

14.
Peacock, C. P. 1987. Measures for assessing the productivity of sheep and goats. Agric. Syst. 23:197-210.

15.
Upton, M. 1993. Livestock productivity assessment and modelling. Agric. Syst. 43:459-472.

16.
White, D. H., P. J. Bowman, F. H. W. Morley, W. R. McManus and S. I. Filan. 1983. A simulation model of a breeding ewe flock. Agric. Syst. 10:149-189.