What is flushing and should I do it?


Flushing is the practice of providing extra nutrition (usually energy) to ewes/does prior to and during the early part of the breeding season. Flushing increases weight gain and body condition in ewes/does which may result in the birth of more offspring (twins and triplets). Although results vary, research has shown that flushing can increase lambing percentage by 10 to 20 percent. Flushing should work similarly in goats, though there are fewer studies documenting its impact.

Responses to flushing can be variable, and it may not always be cost effective. There are many factors which can influence the ewe/doe's response to flushing. Flushing is most effective in females that have not recovered sufficiently from their last lactation. Ewes/does in sub-optimal body condition (thin; 2 to 2.5) will respond more to flushing than ewes/does already in good body condition (average; 3 or better). At the same time, overly thin females (1.5) may not respond to flushing unless the feeding period is long enough. Well-conditioned females (fat; 3.5 or above) usually do not respond to flushing at all.

It may not pay to flush ewes/does during the height of the breeding season. Flushing is more apt to be effective early or late in the season. Mature females tend to respond to flushing more than younger females. It's usually not necessary to flush ewe lambs or doelings as they should already be on a good plane of nutrition, gaining weight from weaning to their first breeding.

Flushing is most beneficial for ewes/does in accelerated breeding programs, as these females are expected to rebreed after a short recovery period. Having ewes/does in good body condition is essential for out-of-season breeding. Improved breeds (e.g., Boer) have higher nutritional requirements and may respond more to flushing than landrace breeds (e.g., Spanish). Flushing will not increase birthing rates above the genetic potential of the flock/herd. Prolific breeds are less likely to respond to flushing.

Flushing is usually accomplished by feeding a better quality harvested forage, by moving ewes/does to a lusher pasture, or by supplementing the forage diet with grain. Grain feeding is most common method. While the most recently published (2007) nutrient requirements for small ruminants don't give nutrient requirements for flushing, the 1985 requirements recommend a 50 percent increase in energy intake. Research conducted at Michigan State University suggests doubling the maintenance requirements for ewes in an accelerated lambing program.

One half to one pound of feed is usually sufficient for most ewes/does. Different feedstuffs can be used for flushing so long as they provide the necessary energy boost. Pasture can be used for flushing, if energy intake is boosted. Specialty crops (e.g., brassicas) are sometimes planted for flushing. Most of the literature suggests beginning flushing 2 to 3 weeks before the onset of the breeding season and continuing it for 2 to 4 weeks after. Earlier flushing may be advisable if animals are in poorer body condition.

According to a Canadian fact sheet, it takes six weeks of grazing a good quality pasture to increase the body condition (of a ewe) by one condition score; 3 weeks for a half score. Body condition changes will occur more rapidly with higher energy feedstuffs. Flushing should not be continued for too long, as it will not likely result in further improvements in reproduction (and may get the ewes/does too fat).

While we don't think about flushing the males, it's important that they be in peak condition at the time of breeding. Sperm production takes 7 to 8 weeks, so it's a good idea to begin supplementing rams/bucks about 8 weeks before the onset of the breeding season. A 10 to 11 percent increase in energy is recommended by the National Research Council (for rams). Aim for males to have a body condition score of 3 to 3.5 at the start of the breeding season. A body condition score of 2.5 may be acceptable for range rams. Don't let rams/bucks get too fat.


Additional reading

Nutritional flushing of small ruminants - Washington State University
Flushing the ewe flock: is it beneficial? - Ontario, Canada