# Comparison of Key Nutrient Content of Commercial Puppy Foods with Canine Dietary Requirements
## 4 Discussion
While there is literature pertaining to the evaluation of major nutrients in food for adult dogs, only a minor portion of it is dedicated to determining levels of other crucial elements, such as fatty acid composition [86; 87; 88]. Dietary fats serve not only as an energy reserve, but also play a crucial role in multiple stages of growth. Specifically, lipids are a pivotal component of cell membranes during cellular development. The fatty acid balance in a puppy's diet can impact membrane structure and integrity, which in turn affects cellular communication, function, brain development and immune system support through their anti-inflammatory properties [19; 26; 27; 34; 89]. A reduced fat level in the diet could also negatively affect the condition of the skin and coat [18; 90]. As demonstrated by [PERSON] [91], none of the seven plant-based dog foods labeled for puppies or all life stages met the MRLs for DHA and EPA regulated by the FEDIAF nutritional guidelines. In the canine body, the activity of enzymes \(\Delta\)5-desaturase and \(\Delta\)6-desaturase is limited, leading to inadequate conversion of precursors into EPA and DHA. Therefore, it is necessary for dogs to obtain EPA and DHA through their diet [14]. The primary source of EPA and DHA acids are marine fish and the oils derived from them (Figure 5) [92; 93; 94; 95]. Uncommon but effective sources of EPA and DHA include genetically modified _Camelia sativa_ seeds [96; 97; 98; 99; 100; 101; 102; 103] or microorganisms that efficiently synthesize LC-PUFAs after genetic modification and optimal cultivation conditions [100; 101; 114; 120; 134]. Herring, mackerel and salmon, along with green-lipped mussel, algae and krill, were utilized as raw materials in the examined formulas. Even though these are deemed as good sources of fatty acids, the amounts used in the diets did not meet the manufacturer's claims on the food package. The issue with utilizing EPA and DHA fatty acids in dry dog food commercially is that LC-PUFAs are highly susceptible to oxidation due to their high level of unsaturation. Consuming products high in fatty acid oxidation products can have adverse effects on the body. Ingesting malondialdehydedehyde (MDA), a byproduct of lipid oxidation, may cause the formation of extra nucleotide linkages in DNA [135]. An imbalanced ratio of \(n-6\) to \(n-3\) fatty acids in the diet primarily reduces the level of \(n-3\) fatty acids in the body [136]. In contrast, a high consumption of \(n-3\) acids can decrease the level of metabolic products of \(n-6\) acids [137]. This, in turn, can reduce the likelihood of developing inflammation, allergies or skin diseases. With regards to commercial granulated diets, [PERSON] et al. [138] showed that the content of certain fatty acids supplied with the diet can be well reflected in blood parameters by influencing the lipid composition of plasma membranes or erythrocytes. This finding can be used to determine the intake of fatty acids, particularly \(n-3\), which our study shows is present in modest concentrations  
Figure 5: Potential sources of dietary LC–PUFAs EPA and DHA based on [92; 96; 97; 98; 99; 100; 101; 102; 103]. in certain commercial diets. Fish oils that are rich in the LC-PUFAs EPA and DHA were found to lower levels of blood triglycerides in dogs [139; 140]. An excess of \(n-6\) fatty acids is a threat to the proper utilization of \(n-3\) fatty acids supplied with food because fatty acids from the \(n-3\) and \(n-6\) families compete for the same enzymes required to convert these acids into a usable form [141; 142; 143]. Additionally, dogs that received menhaden oil and flaxseed oil in their diet with \(n-6/n-3\) ratios of 0.34:1 and 0.38:1, respectively, exhibited lower superoxide production, which has been associated with an increase in reactive oxygen species in the body [144]. These findings were compared to dogs fed diets with \(n-6/n-3\) ratios such as 100:1 (safflower oil) and 9.7:1 (beef tallow), both of which had higher superoxide production. [PERSON] et al.