Inner needle drop is a natural occurrence in pines and other evergreens in the fall. The following is more information that gives details and will calm many of your thoughts that the trees are sick.
White pines with inner needles turning yellow are not dying; they are just experiencing normal fall yellowing and leaf drop. While evergreens do not lose all their leaves in the fall, individual leaves/needles do not last on the tree forever. If trees are small, you can shake them and loosen the needles. You will end up with a nice pine straw mulch below the trees.
In some years, the natural needle drop will occur in a relatively short period of time, with rapid and noticeable browning of the older needles, which leads to fears the tree is dying. In other years, people don't even notice it happening, because the browning is spread over a long period of time.
The symptoms are normal for the fall. Pines and arborvitaes normally shed their oldest needles in the fall. White pines usually retain their needles for one to two years. The older needles, those toward the center of the tree, turn yellow before dropping. Older arborvitae leaves turn a reddish brown. Natural needle discoloration may be more noticeable on trees that have experienced root stress due to less than optimal growing conditions. Extended dry periods during the summer months, as well as sites with poorly drained, heavy clay soils, may accentuate root stress to pines. Since the newest growth (this year's needles) are still green and healthy in appearance, you can be assured that this yellowing phenomenon is a natural one.
Optimal horse health
Choosing the correct diet for a horse can go a long way for its nourishment. It is important to feed horses based on age and weight.
Many horses don't need to be fed any grain, but a colt will. Owners should feed younger horses more grain because they are growing and developing muscles and bones.
Depending on the type of hay that a horse eats, there are a couple different grain mixes horse owners can use. If feeding with alfalfa hay, use a mix lower in calcium and higher in phosphorus. If owners are using a grass hay, which has a naturally lower amount of calcium, the grain can contain similar amounts of phosphorus and calcium.
Besides grain there are other important factors in horse feed. Using a grass hay will provide drier food and less chance of mold, but it sacrifices protein, vitamins and minerals. Using alfalfa hay will provide more minerals than grass hay, but it also runs the risk of becoming moldy because it is harder to properly prepare and takes longer to dry out.
Regardless of what hay a horse owner uses, it is most important to have enough food for a horse. Otherwise, horses will chew on things to keep their teeth busy. To get the most nutrition from the forage, search for hay that has a lot of leaves and little stem.