Why did the officer take such an interest in the younger children? in the book night

There were some homosexual Nazis who were trafficking in children, and using them for their own pleasure.

Explanation:

Wiesel describes the German tent leader with details that reflect why the officer coveted and took such an interest with children.  The Nazi officer is described as one with "an assassin's face, fleshy lips, hands resembling a wolf's paws."   This helps to illuminate the animalistic and savage way that children were coveted.  Using food as a technique to groom the children in order to gain their confidence, the Nazi officer is described as having "liked children."  In a parenthetical note, Wiesel suggests that such affection "was not entirely altruistic."  The "veritable traffic of children" was referred to as a reason why children were shown so much affection.  Such detail brings out the horror intrinsic to the Holocaust.  The significance of the officer taking such an interest in the younger children for his own sexual gratification only underscores such a reality.

"facing the rising sun of our new day begun

let us march on till victory is won.",

because the rising sun is a symbol of hope.