Money
You start Level 48 of "Chicken Chase" with $400, and your bank holds a maximum of $800. This severely limits your ability to purchase chickens and upgrades. You can't buy magic or holy chickens, since they each cost $1,000 or more, but you can still hatch them from eggs. You're also limited to two upgrades, since the upgrade cost starts at $250 and doubles with each purchase. Money is only a concern at the very beginning of the level, so collect all coins whenever you find them. Later, you'll sell eggs that will max out your bank total.
Chickens
You begin Level 48 with four "layer" chickens, which lay eggs, and one "broody" chicken, which hatches eggs. You need many layer chickens to reach the 100-white-egg goal, but you may purchase only 10 layer chickens during the level. You may buy as many broody chickens, which cost $200, and roosters, which cost $500, as you like. Buy three layer chickens for $100 each as soon as the level starts, leaving your remaining $100 for chicken feed. Buy the remaining layer chickens as soon as you can afford to.
Upgrades
Ravens and wolves steal your chickens, and you can't afford to lose any in Level 48. Invest in the two weapon upgrades -- one doubles your firing power, and the other expands your range. You can still get other upgrades if you click the green question-mark box. This box has both positive and negative effects, and it's best to avoid clicking it when you're close to achieving your goals.
Eggs
The 100-egg goal should be your first priority, and you have to collect every white egg your chickens lay. Collect and sell all white and red eggs. Hatch dark blue eggs until you have ten broody chickens, and then start selling those eggs. Hatch each black egg to produce a rooster, which will protect your chickens from ravens. The more roosters you have, the better off you'll be. Keep the light blue eggs, but don't hatch them yet. However, you can hold only 18 eggs at a time. When the row of eggs at the bottom of the screen is full, your chickens will stop laying them.
Magic Chickens
Magic chickens, which hatch from light blue eggs, eat eggs instead of chicken feed, which presents a problem on Level 48. Don't start hatching them until the last two or three minutes. Since you're saving light blue eggs throughout the level, you can wait until you've accumulated 100 white eggs before you hatch magic chickens. If time is running low, you can start hatching when you have 80 or more white eggs in stock. Stop selling eggs when you start hatching magic chickens -- they'll die if they don't have eggs to eat.