Which animal class notably cannot synthesize Vitamin C themselves?

The correct answer highlights the distinctive metabolic requirement of certain animal classes regarding Vitamin C synthesis. Rodents and nonhuman primates share a key characteristic: they lack the ability to synthesize Vitamin C (ascorbic acid) endogenously due to a mutation in the gene responsible for its synthesis. Consequently, this necessitates an exogenous source of Vitamin C in their diet to maintain health.

In contrast, ruminants, such as cows and sheep, can synthesize their own Vitamin C, effectively negating the need for dietary intake. This physiological difference is crucial in veterinary science and animal husbandry, impacting dietary formulations for laboratory animals and livestock.

Understanding the dietary needs surrounding Vitamin C is essential for maintaining optimal health in species that cannot produce it. Hence, knowing that both rodents and nonhuman primates cannot synthesize Vitamin C provides a critical insight for those working in laboratory animal care and research.