Rumen bypass protein maximise growth potential

The use of rumen bypass protein supplements has traditionally only been of interest to milk producers looking to boost cow performance. But increasing the supply of high quality protein offered to young beef cattle can also produce substantial improvements in growth, efficiency and profitability, especially for bulls.

And according to KW technical manager Michael Marsden, much of the genetic potential for bull beef growth is realised during the first six months, when the combination of testosterone and rapid lean tissue deposition allows extremely efficient weight gain.

“However, there is a problem in that current beef rationing models overestimate the supply of metabolisable protein from the diet and underestimate requirements, leaving potentially fast growing young cattle short of protein and underperforming,” says Dr Marsden.

For beef producers looking to increase protein supply there are two broad options. The first is to better support rumen microbial protein production with an improved supply (or better balance) of rumen degradable protein (RDP) and fermentable carbohydrates.

“But for many well-formulated beef rations, the rumen will already be near capacity,” adds Dr Marsden. “So the second, and in most cases more practical and cost-effective option is to add rumen bypass protein supplements that supply extra digestible undegraded protein (DUP) direct to the animal’s gut.

And this has been backed up on-farm, where young cattle have responded well when small quantities of heat-treated rapemeal or rumen-protected soya bean meal are added to grower rations, explains Dr Marsden.

“Although alternative sources of rumen bypass protein for use in beef rations appear costly at around £405/t, rumen-protected soya bean meal is actually the most cost-effective source of extra rumen bypass protein,” says Dr Marsden (See table 1).

Table 1 – Comparative costs of rumen bypass protein (DUP) 

   Price* (£/t) DUP content (g/kg FW)  DUP value (p/100g DUP
 Rumen-protected soya bean meal  422 315 13.4
 Heat-treated rapemeal  254  150  16.9
 Bioethanol wheat distillers’ feed  215  108  19.9
 Hi-pro soya bean meal  374  183  20.4
 Rapemeal  217  100  21.7
 * Prices quoted correct at time of going to press, 29t bulk deliveries Nov-Apr, on-farm within 50 miles of source, prices will vary with load sizes and distance from source.   

Theory in practice

And on Gary Allis’ black-and-white bull rearing and finishing unit at Furze Hill Farm in Lincolnshire, the theory of feeding rumen bypass proteins is proving highly effective.

As one of KW’s Compass Programme demonstration farms, the unit initially raised the protein content of the grower ration to 15% on a freshweight (FW) basis by using heat-treated rapemeal as a lower-cost alternative to soyabean meal.

The results were so dramatic that the level of rumen-bypass protein was increased further, using rumen-protected soyabean meal (0.25kg a head a day) to achieve a 16% crude protein ration (FW basis) that contains 55g/kg FW of DUP (table 2).

Table 2 – Beef grower ration at Furze Hill Farm, Lincolnshire


kg FW/t

 Maize meal  442
 Heat-treated rapemeal  175
 Sweetstarch  166
 Soya hulls  135
 Rumen-protected soya bean meal  60
 Vitamin/mineral premix  11
 Live yeast  11
 Energy (MJ ME/kg DM)  13.4
 Crude protein (% of FW)  16.0
 Rumen ypass protein (g DUP/kg FW)  55

Fed until cattle reach five to six months of age, the ration is helping finish the unit’s Holstein Friesian bulls at just 11 months of age, with an average carcass weight of 230kg. And recent performance is looking even better, says Mr Allis.

“All the changes to the feeding in the grower and finisher periods have improved how the cattle grow, bloom and fill out,” he explains. “It’s contributed massively to the changes we’ve made, cutting overall finishing time by around five months, although we are now also selling a lighter animal.

“In fact, one animal reached a carcass weight of 282kg at just 12 months and 10 days old – that’s impressive performance for a Holstein Friesian bull.”

And there’s a clear return on investment in supplying this extra high-quality rumen bypass protein, according to Dr Marsden. At current prices, increasing ration protein levels 1% by adding 50kg FW/t of rumen-protected soya bean meal in place of equal parts cereal and rapemeal, would increase ration cost by around £10/t, or just 5.75p a head a day for a typical 200kg LW animal.

“Based on a carcass value of £1.50/kg LW, growth rate would have to increase by just 38g a day to break even, compared with a typical response of 100-200g a day or more. Not only that, but the high feed conversion ratio – typically between 3:1 and 4:1 at 200kg LW – would make the gains much more cost-effective than when cattle are older, when the feed conversion ratio falls to between 7:1 and 8:1.”

Key points:

  • Current beef rationing models overestimate protein supply
  • Young cattle capable of fast growth often left undersupplied with protein
  • Rumen bypass protein supplements the most effective solution
  • Payback confirmed on-farm: 2.9p a head a day for 35-42p extra growth