Commercial sheep production from continuous and rotational grazing over thirty‐five years in the Karoo

Abstract

The rainfall and production records of a sheep farm of 915 ha in the 287 mm rainfall region of the Karoo are documented over a period of 35 years.

Rainfall records indicate a decrease of 4 mm per annum in rainfall from 1939 to 1973. Production records are presented for a period of continuous grazing (1939 to 1948) followed by a period of rotational grazing on a two‐paddock system (post 1948). Comparison of these periods demonstrates that, at a stocking rate of one sheep to 2,1 ha throughout the entire recording period, the total annual wool production from 3 300 sheep increased from 20 412 kg (pre 1948) to 24 494 kg (post 1948), i.e. 20%. The number of lambs raised annually increased by 19% in the second period. Wool per sheep increased from 5,4 kg to 6,2 kg (13%) per annum, wool production per ha increased from 1,8 kg to 2,3 kg (26%) per annum and wool per unit of rainfall increased from 1 570 kg per 25 mm rainfall to 2 605 kg (65%).

The significance of the results is evaluated in relation to continuous grazing and multicamp systems.

Uittreksel

Die reenval en produksierekords van ‘n skaapplaas van 915 ha in die 287 mm reënval gebied van die karoo oor ‘n periode van 35 jare word behandel.

Reenval rekords toon dat die jaarlikse neerslag vanaf 1939 tot 1973 in jaarlikse vermindering van 4 mm ondergaan het. Produksierekords word aangebied vir ‘n periode van aanhoudende beweiding vanaf 1939 tot 1948, gevolg deur ‘n periode, na 1948, van wisselweiding op ‘n tweekamp stelsel. Vergelyking van syfers vir hierdie onderskeie periodes wys dat ten spyte van effens her reënval, die wisselweidingsperiode ‘n verhoging van (i) 20% in totale jaarlikse wolopbrengs; (ii) 19% in getal lammers jaarliks grootgemaak, (iii) 13% in wolopbrengs per skaap; en (iv) 62% in wolopbrengs per eenheid reenval, gelewer het. Die betekenis van die resultate word geëvalueer met betrekking tot aanhoudende en wisselweiding.

Notes

Present address: “The Mills”, Hanover, Cape Province

Present address: Charleville Pastoral Laboratory, Queensland, Australia