ANN 121: Applied Animal Nutrition-I (2+1)

FLUSHING

• A low plane of nutrition may reduce the secretion of gonadotrophic hormones and hence affect fertility.

• In sheep, there is often a period of several months between weaning and remating during which the ewes may be on a low plane of nutrition.
• It has been found that ewes which have been better fed during this period, and for this or other reasons are in better condition at the start of the breeding season, are more likely to have multiple ovulations and hence bear twins or triplets.
• This effect is utilised in the practice known as flushing, in which ewes are transferred from a maintenance level of feeding to a higher level for 4-6 weeks,beginning 2-3 weeks before the start of the breeding season.
• Flushing often increases the lambing percentage (lambs born per 100 ewes) by 10–20 per cent. This effect is associated more with improved than with improving body condition, and could just as well be obtained by preventing the depletion of reserves.
• Flushing is also used to increase litter size in gilts, the improved level feeding being imposed for about 10 days before first mating.
• In cows, only a single ovulation is normally required, and therefore flushing is not needed.
• It is recommended, however, that both dairy and beef cows should be fed to gain weight from about day 70 of lactation so that re-conception is achieved without difficulty.