Effects of RFI classification and strategic supplementation of low quality diets to optimize beef cow performance

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The beef cow is often managed to meet nutrient requirements for only a limited time of the year. During the rest of the year, the cow may be fed diets, deficient or limiting in one or more nutrients. Ontario is blessed with the ability to produce nutrient dense forages which can be are wasted on beef cows if fed ad libitum throughout the year. Cow-calf producers can make more money on these high quality forages by feeding them to weaned calves and growing cattle. Nutritional strategies need to be developed to use lower quality forages where there is strategic supplementation of nutrients to ensure the health and reproductive success of the gestating cow. This approach offers the most viable solution to lower cost of production and increase returns to cow-calf producers. The study will evaluate the following nutritional management programs: 1) feeding high quality forages ad lib to ensure intake of all essential nutrients but at a cost of wasting nutrients and depositing excess condition on cows, 2) feeding high amounts of crop residues which may compromise the nutritional needs of the cow without supplementation, & 3) strategic supplementation of low quality diets such that supplementary nutrients are only provided at specific time intervals (weekly, twice per week, or 3 times per week). Research is also needed to examine genetics of feed efficiency or residual feed intake (RFI) in beef cows and evaluate these genetics across diverse nutritional programs. Cows classified as low RFI are more efficient at converting feed for maintenance and production purposes. Costs of production should decrease if the cow herd is made up predominantly of low RFI cows. The experimental design of the project will test the success of specific nutritional management programs and how specific genetics perform when nutrients are limiting. This will include assessing growth performance, body condition, reproductive performance, and calf production. This project will demonstrate how specific genetics perform across diverse nutritional regimens, and how strategic supplementation of low quality diets can be used to lower costs of production for Ontario cow-calf producers.