Effect of replacement rate, production system and beef price on total herd efficiency

Abstract

The influence of replacement rate (R), price (c/kg carcass weight) and two production systems on total herd efficiency was investigated. R was assumed to be either 15% (minimum),l9%o (point in between) or 23Vo (maximum). Percentage differences (minimum, point in between, maximum) in beef prices for the period 1984 to 1992 (RSA Livestock and Meat Statrstics) were calculated for eight-month-old weaners vs. cull cows and l8-month-old market animals vs. cull cows, respectively.T hesep ercentagep rice differencesw ere usedt o calculater elative income per hectare( I/ha) for two production systems, namely, an 8/18 month system (steers sold at eight months of agelsurplus heifers sold at 18 months of age) and an 18/18 month production system (all market animals sold at 18 months of age). From the results it was clear that maximum R is applicable on systems where cull cows are, on a per-animal basis, of higher value than both eight-month-old weaners and 18-month-old market animals. Comparison between the two production systems based on adjusted Vha and 20Vo R (assumed as standard practise in South Atrica) has shown the 18/18 month system to be more efficient. This study also indicated that longevity is not important for maximizing efficiency, since R should be maximized.

Die invloed van vervangingstempo( R), verskille in vleispryse( clkg karkasmassae) n twee produksiestelselso p totale kuddedoeltreffendheidi s ondersoek.R was vasgesteol p onderskeidelik1 57o( minimum),l9%o (punt tussenin)e n 23Vo( maksimum). Persentasieverskille(m inimum, punt tussenin,m aksimum) in vleisprysev ir die tydperk 1984 tot 1992 (RSA Vee- en Vleisstatistieke) is vir onderskeidelika gt-maande-speenkalwervss . 18-maande-markdierea, gt-maande-speenkalwervss . uitskotkoeie en 18-maande-markdierev s. uitskotkoeieb epaal.H ierdie persentasiep rysverskille is gebruik om berekenings vir relatiewe inkomste per hektaar (Ifta) vr die twee produksiestelselsn, aatnlik die 8/18-maande-stelse(ls peenkalwers verkoop op ouderdom agt maande/surplusv ersev erkoop op ouderdom l8 maande)e n die 18/18-maande-stelse(al lle markdiere op ouderdom 18 maandev erkoop), te maak. Maksimum R is van toepassingo p stelselsw aar uitskotkoeie op 'n perdier- basism eer werd is as sowel agt-maande-speenkalweresn 18-maande-markdiere'.n Vergelyking gegrond op aangepaste Vha en 20VoR (beskou as standaardi n Suid-Afrika) tussen die twee produksiestelselsh, et bewys dat die 18/18- maande-produksiestelseml eer doeltreffendi s. Hierdie studieh et verdera angeduid at langslewendheidn ie belangrik vir die maksimaliseringv an doeltreffendheidi s nie, aangesienR so groot as moontlik moet wees.

Keywords: Production system, replacement rate, total herd efficiency.