Copper is an essential trace element for all animals and is especially important for fetal development. While testing commercial diets, the investigators found that queens fed three of these diets produced offspring with clinical signs compatible with copper deficiency, including neonatal death, underweight kittens, and collagen abnormalities. These diets contained cupric oxide, a source of copper that cats can’t utilize.
Queens consuming diets containing twice the current recommendation of cupric oxide had the lowest rate of conception, while queens consuming a diet with double the recommendation of copper sulfate had the highest rate of conception. Increasing copper sulfate in the diet significantly decreased the time it took for queens to conceive. Queens consuming the copper oxide diet took four times as long to conceive as those on the highest concentration of copper sulfate. This study also demonstrated that plasma (blood) copper concentration is a poor indicator of copper status in the cat. The objective of this study is to find non-invasive methods to determine the copper status of queens to ensure the birth of normal kittens.