Grass silage is best route to building protein levels

Beef producers should concentrate on improving grass silage quality rather than buying protein supplements, according to nutritionist David Peers.

Reporting on a trial run on Alwyn Jones’ 81ha North Wales farm, Dr Peers acknowledged a worrying fall in crude protein levels in a high proportion of Welsh first-cut silages in recent years.

“There is a great deal of interest in whether additional supplementation can produce a cost effective improvement in performance, particularly with Continental cross cattle,” Dr Peers claimed.

“Like many other producers, Mr Jones was wintering yearling store cattle on ad-lib silage alone, which kept costs down and encouraged compensatory growth after turnout. But he was anxious that low grass silage protein was preventing him reducing length of time capital was tied by increasing time to slaughter.”

The trial compared weight gains of three groups of cattle fed good and low protein grass silages, with and without protein supplementation.

For the first 41 days all animals were on ad-lib silage with an ME of 11 and 14% crude protein. Then for the next 38 days they were offered silage with an ME of 10.4 and 12% crude protein.

Two groups were also fed an additional 210g a day of protein, supplied by either 0.45kg a day of soya meal or 0.6kg a day of rape meal.

The silage only group gained 0.46kg a day on the high quality silage and 0.11kg a day on the lower protein fodder. Feeding extra protein had no effect.

“Supplementing with either soya or rape meal produced marked increases in daily gain on both lower quality silage and over the whole trial,” Dr Peers told visitors to an open day.

The cost effectiveness of protein supplementation was adversely affected by the high price charged by merchants for small quantities. An extra daily weight gain of 0.1kg a head a day was required to break even.

Overall the silage only group put on 0.29kg a head a day. Cattle given soya gained 0.40kg a head a day and the rape meal group 0.46kg a head a day.

“There seems to be a simple message from what was admittedly a small-scale trial using 76 cattle. It pays to make good quality silage and have it analysed before spending on protein supplements.

“Most farmers who overwinter store cattle will be happy with the 0.46kg a head a day gain achieved on good silage alone, but concerned by the 0.11kg a head a day gain on just the lower quality silage.”

It was also worth noting conservation costs are as high for poor quality silage as for high quality material. With beef cattle it was a case of balancing yield and quality, but sward composition, stage of growth and use of an additive all affect quality.

Institute of Grassland and Environmental Research scientist David Davies urged open day visitors to consider whether an additive could boost protein in silage.

The crude protein figure was only a crude guide. The important measure was true protein, which could be boosted by using a fermentation-accelerating additive.

A good product will inhibit plant enzymes which break down protein in the silo. This leaves more true protein to be used in the rumen. This was particularly important when ensiling crops taken from clover rich swards.

Outwintering feed trial
Average daily LWG 0-41 days 41-79 Overall
Silage only 0.46 0.11 0.29
Silage + soya meal 0.39 0.31 0.40
Silage + rape meal 0.31 0.50 0.46