Analyses of the variation in feed efficiency measures of MOET-produced Droughtmaster SA cattle in intensive and extensive feeding systems

Abstract

Feed is one of the major expenses in the beef industry, so it is beneficial to select animals that consume less feed for the same level of production. This study aimed to compare the feed efficiency and residual feed intake of Droughtmaster SA weaners of different double muscling genotypes (F94L and NT821) produced by multiple ovulation embryo transfer (MOET) between the GrowSafe system and veld. In this study, several feed efficiency measures were recorded from 150 Droughtmaster SA bulls and heifers over two years. Primary data obtained for evaluation showed that there was a positive association between the double muscling mutations and low residual feed intake (efficient animal). Sex (male and female), residual feed intake rank, double muscling mutation (F94L, NT821, None), and other efficiency variables were analysed using the General Linear Model using the SPSS Software (Version 29). The results confirmed that variations in residual feed intake do exist. The research also suggested that the ranking of efficient animals in the GrowSafe system and on veld remained the same. The results of the study validated that the GrowSafe system can identify the same bulls and heifers with low RFI as on veld, which indicated that the performance testing period can be significantly reduced and cattle can be marketed at an increased price in a shorter time frame. There was no significant difference in efficiency parameter ranking of weaners in the intensive feeding system (GrowSafe System) versus on veld, as well as no significant difference between efficiency parameter measures of different double muscling genotypes when the entire population of cattle were accounted for. Significant differences did exist between efficiency parameter measures of different double muscling genotypes within gender groups. Subsequently, this may lead to decreased reproductive efficiency, since Droughtmaster SA cattle are an early maturing breed. The results of this study may have a practical implication on breeding goals, since selecting more feed-efficient animals may result in less efficient animals in terms of reproduction.