Residual feed intake in beef cattle

Abstract

-Providing feed is a major input cost in beef production, hence improvements in the efficiency of feed utilisation will reduce the cost of production. Residual feed intake (RFI) is a measure of feed efficiency, and is defined as the difference between an animal's actual feed intake and its expected feed intake based on its size and growth. It is independent of the level of production, and the lower the value the more efficient the animal is. This paper examines the current state of knowledge on RFI. Available information indicates that postweaning RFI is moderately heritable, and that selection for low RFI will result in progeny that consume less feed for the same level of production as progeny of high RFI cattle. Under ad libitum feeding, RFI is phenotypically independent of growth traits. There is a weak genetic relationship between RFI and fatness but additional studies are needed to assess the magnitude of this relationship in different breeds, sexes, ages and feeding regimes. Residual feed intake is believed to represent inherent variation in basic metabolic processes which determine efficiency. Economic analyses of genetic improvement schemes that incorporate testing of individuals for RFI have yielded substantial economic benefits over and above existing schemes that do not include RFI testing. Selection for low RFI has an additional benefit of reducing greenhouse gas emissions by cattle.

Residual feed intake and relationships with performance of Nellore cattle selected for post weaning weight

“…After five years of diverging selection, Australian scientists confirmed that the selection of animals for efficiency (low residual feed intake) resulted in a progeny of lower intake and slightly thinner, but the performance was similar to the animals selected for high residual feed intake (Arthur et al, 2008). However, those results of residual feed intake diverge on age and production system.…”

Residual feed intake as a criteria for feed efficiency selection

“…Outra maneira de se calcular o consumo predito seria utilizando sistemas como o NRC (2000), descritos por Arthur et al (2001) e Arthur & Herd (2008) ou realizando padronizações para a energia metabolizável, obtendo o consumo de matéria seca padronizado , o que reduziria os erros associados às diferenças energéticas das dietas.…”

Caracterização do consumo alimentar residual e relações com desempenho e características de carcaça de bovinos nelore

“…A regulação fisiológica do consumo alimentar residual está provavelmente ligada a centenas de genes (Herd et al, 2008), existindo ao menos cinco processos fisiológicos nos quais a variação poderia surgir: digestão, incremento calórico associado a ingestão, metabolismo tecidual, padrão de alimentação e atividades .…”

“…Após cinco anos de seleção divergente, australianos (Arthur et al, 2008) confirmaram que a seleção para baixo CAR (mais eficientes) resultou em uma progênie que consumiu menos e foi ligeiramente mais magra, mas que obteve desempenho similar aos selecionados para alto CAR (menos eficientes).…”

“…A regulação fisiológica do consumo alimentar residual está provavelmente sob o controle de muitas centenas de genes (Herd et al, 2008) e existem pelo menos cinco processos principais pelos quais a variação em eficiência pode surgir. De acordo com Richardson e Herd (2004), diferenças em digestão contribuem conservadoramente em 10% da variação, padrão de alimentação em 2%, incremento calórico associado à digestão em 9% e atividade em 10%.…”