Effects of oilseed supplementation on performance and reproduction of beef cows and their progeny

A major goal of cattle producers is to optimize reproduction of beef cows while minimizing feed costs. Lipid supplementation and its potential nutraceutical effect is one method that has been researched in an effort to accomplish this goal. The research reported in this dissertation was conducted to determine if lipid supplementation from whole oilseeds could improve reproductive performance of beef cows. Three separate performance experiments were conducted as part of this research. In the first performance experiment, multiparous spring calving cows were supplemented with a negative control, a positive control, or whole sunflower seed during late gestation. Although first service conception rates were greater for cows fed the positive control or whole sunflower seed compared with cows fed the negative control, pregnancy rates were not influenced by supplement composition. In the second performance experiment, multiparous spring calving cows were supplemented with a positive control, whole linoleic sunflower seed, or whole mid-oleic sunflower seed during late gestation. Weight gain of cows fed sunflower seed supplements was lower than cows fed the positive control. However, cow reproduction was not influenced by supplement composition. In the third performance experiment, cows of varying age were supplemented with either a positive control or whole soybeans. No differences in reproduction were observed among cows fed either supplement. In addition to the performance experiments, two intake and digestion experiments with oilseeds were conducted. In the first intake and digestion experiment steers received no supplement, a soybean hull-based supplement, whole linoleic sunflower seed, or whole high-oleic sunflower seed. Hay intake was not influenced by supplement composition; however, dry matter and fiber digestion were reduced with sunflower seed supplementation. In the second intake and digestion experiment, cows of varying age were supplemented with either a positive control or whole soybeans. Neither cow age nor supplement composition influenced any of the intake or digestion measurements. In conclusion, these experiments suggest that a limited amount of whole sunflower seed or whole soybeans can be fed as a winter supplement to beef cows during late gestation without impacting cow reproduction or calf performance.