Delivery method and supplement consumption by grazing ruminants: a review.

The effectiveness of supplementation programs is affected by the ability to reduce intake variation and to meet target supplement consumption. A review was made of factors affecting variation in individual animal consumption of supplement by grazing cattle and sheep, including supplement type and feeding method, animal dominance and social interactions, and forage availability. The effects of palatability were not included. The proportion of animals not consuming supplement is increased by limited trough space, small supplement allowance, self-fed supplements, neophobia to feed or feed delivery devices, and group feeding situations. Variation in individual animal supplement intake is increased by excessive trough space, limited supplement allowance, self-fed supplements, feed and feed delivery equipment neophobia, and individual feeding of supplements. Factors influencing the percentage of animals consuming the target amount of supplement need to be more clearly identified. There seems to be an optimum level of feeding competition that reduces intake variation and improves the proportion of animals consuming adequate amounts of supplement, but this optimum varies with the feeding situation.