Wetenschap - 20 juni 1996

Sheep diet benefits production system

Delayed growth in small ruminants during periods of feed quality restriction can potentially be fully compensated and yield an even better carcass quality. Putting sheep and goats on a balanced diet during the dry season will reduce the grazing pressure by 65% in Iran's extensive sheep production system. The animal's intake of low quality feed can be increased and scarce high quality feeds more efficiently used. This is Iranian Azizollah Kamalzadeh's conclusion in his PhD thesis Prospects of compensatory growth for sheep production systems, which he will defend coming Wednesday, June 26.

Kamalzadeh explains the importance of sheep and goats in his country. These animals provide 70% of the red meat and 40% of the milk. They also provide other products like skin and wool, and are a form of investment. Furthermore, sheep and goats reproduce at a faster rate than larger ruminants like cows. This capacity provides an extra advantage: after a drought or disease, a herd of sheep can be re-established more rapidly.

Kamalzadeh used his research to determine the physiological changes that occur during quality feed restriction and realimentation in sheep, and compared the results with similar measurements taken from control animals. He also evaluated the productivity of existing intensive and extensive sheep production systems. This research could form the basis for designing alternative grazing systems to replace the extensive grazing system commonly found in Iran. These would allow regeneration of the pastures and prevent land degradation. In the long run, a better tuning of the number of animals to an area's carrying capacity could further increase productivity. One of Kamalzadeh's most remarkable statements reads,Body reserves are an underexploited resource in improving the sustainability of ruminant production systems.