Question

I own a 13-month-old filly, Millie, that’s in moderate weight. I am moving her to a farm closer to me that has better pasture than she has now, and she will be turned out all day, every day. With this change in pasture, what’s the best feed for her? Right now, Millie receives about 8 quarts of a “breeding feed,” which is intended for young horses as well as broodmares. The pasture she’s currently on is mediocre at best, so she’s also given as much orchardgrass/alfalfa (lucerne) hay as she wants. Maybe free-choice mineral is the way to supplement pasture? What’s your advice?

Answer

The best way to ensure your filly is receiving appropriate nutrition is to provide a fortified feed, as it is impossible to determine intake levels of free-choice mineral products, especially if Millie has pasturemates.

Although nutritionists prefer to discuss feed amounts in weight, not volume, Millie is probably consuming approximately 8 lb (3.6 kg) of feed per day. Feeding to maintain steady growth rate is important, and it may take a period of time to assess how much concentrate feed she needs when offered free-choice access to pasture grazing.

How much grass pasture is available to Millie and how this alone meets her energy needs will dictate the most suitable concentrate. If possible, I would maintain the current feeding program during Millie’s transition to her new home. If you start to notice excess weight gain or an increase in her growth rate, I would slowly decrease her concentrate to find the right balance between pasture and feed. Good-quality grass pasture can make up a significant proportion of the calories needed—sometimes pasture can completely meet or exceed energy requirements—so less concentrate would be needed.

A diet review is in order if you begin to feed Millie less concentrate than recommended by the manufacturer. If you find that she needs very little concentrate once she’s been on pasture for a while, then switching to or incorporating a ration balancer into your feeding program will provide her with vitamins and minerals in a much smaller amount, 1-2 lb (0.5-0.9 kg) per day, but still allows you to assess her intake level and know she is getting complete nutrition.