Supplementing pasture-fed dairy cows with pasture silage, maize silage, Lotus silage or sulla silage in summer - does it increase production?

Abstract

Forages suitable for supplementing pasture-fed dairy cows over summer-autumn must provide adequate dry matter (DM) and increase milk yield above that produced by cows grazing normal ryegrass/white clover pasture, without compromising milk composition. A trial was conducted in January-February 2001 to compare the benefits obtained from feeding four types of silage. There were two silages that contained condensed tannins (CT) (birdsfoot trefoil (Lotus corniculatus) and sulla (Hedysarum coronarium)), maize silage or traditional ryegrass-dominant pasture silage, all fed at 5 kg DM/cow/d with restricted pasture. Cows on the restricted pasture (control) treatment and those fed the silage treatments were offered an allowance of 25 kg DM pasture/cow/d, while the full pasture cows were offered 50 kg DM pasture/cow/d. Silage supplementation, regardless of silage type, increased both total dry matter intake (DMI) and milk production compared with the restricted pasture treatment. Cows on the Lotus silage supplement, and the full pasture treatment had significantly higher milk yields than the other silage-supplemented cows, all of which had similar milk yields. For the Lotus silage treatment, the high milk yield was probably due to a combination of the higher nutritive value of the silage, and to the action of CT, because the total DMI of the cows on the Lotus silage was the same as that of cows on the pasture silage and maize silage. The high milk yield of the full pasture treatment was mainly a result of the cows having a significantly higher total DMI than cows on all the other treatments. This trial has demonstrated the potential benefit of silage supplementation, particularly with Lotus silage, for increased milksolids yield in summerautumn when low pasture growth rates and quality may otherwise limit production. Keywords: condensed tannins, dairy cows, Lotus, maize, milksolids, ryegrass, silage, sulla, supplementation