Maximum herd efficiency in meat production II. The influence of growth and reproduction

Abstract

A general method is developed for the evaluation of herd efficiency in terms of efficiencies for growth and reproduction. Almost the only requisite knowledge for the application of this method is the value of the allometric slope between the cost of cumulate feed intake and body mass for a target population. The evaluation of reproduction efficiency involves reproduction and replacement rates, early fertility, and degree of fertility at first mating. Growth efficiency is discussed in terms of cumulate YS. constant period efficiency and the influence of a likely negative genetic relationship, induced by selection, between components like preweaning and postweaning efficiencies. Finally, some consequences are derived for the effect of constant costs per time unit on total efficiency.

'n Algemene metode is ontwikkel vir die evaluasie van kuddedoeltreffendheid in terme van doeltreffendhede vir groei en reproduksie. Omtrent die enigste vooraf-kennis wat nodig is vir die toepassing van hierdie metode is die allometriese helling tussen geakkumuleerde voedselinname en liggaamsmassa vir 'n  toepassingsbevolking. By die evaluasie van reproduksiedoeltreffendheid is reproduksie- en vervangingstempo's, vrore vrugbaarheid en graad van vrugbaarheid
by eerste paring, betrek. Groeidoeltreffendheid is bespreek in terme van  geakkumuleerde YS. konstante periode doeltreffendhede en die invloed van 'n moontlike negatiewe genetiese verwantskap tussen voorspeense en naspeense
doeltreffendhede wat deur seleksie gernduseer mag word. Laastens word sommige afleidings oor totale doeltreffendheid gemaak vir die geval van konstante kostes per tydseenheid.