Maize benefits bulls a lot more than steers
By Jessica Buss
BULLS perform better on maize finishing diets than steers, but Holsteins take days longer to finish at the same weight as crossbreds, according to a recent study by CEDAR, Reading University.
The third year of MAFF, MLC and Agribusiness-funded research into feeding beef cattle on maize compared groups of bulls and steers.
Both groups comprised of pure Holsteins and Simmental x Holsteins. Starting weights were similar for both bulls and steers at 467kg and the 96 animals were fed a mixed ration of 82% maize and 18% concentrate, ad-lib, explains CEDAR director David Beever.
All bulls achieved good liveweight gains and previous years studies had shown the benefits of maize compared with grass silage diets (Livestock, Sept 14).
In this study, bulls showed a 21% improvement in liveweight gain compared with steers and were 23kg heavier at slaughter, with average daily gains of 1.63kg and 1.35kg, respectively.
"In relation to body weight, however, daily dry matter intake was similar for bulls and steers which resulted in bulls having a much better feed conversion efficiency," says Prof Beever.
Bulls required 6.5kg feed DM for each kg liveweight gain, compared with 8.2kg/kg gain for steers. It took bulls just 86 days to gain 141kg, while steers needed 93 days to gain 125kg.
Breed differences were also reported, but these were smaller than the difference between steers and bulls, he adds.
Holsteins ate more than Simmental crosses and feed conversion efficiency was poorer at 8kg diet/kg gain for Holsteins compared with 6.8kg/kg gain for the crossbreds. This may have been due to the Holsteins having higher maintenance requirements.
But pure Holsteins had satisfactory rates of gain of 1.41kg/day compared with 1.56kg/day for the Simmental cross cattle. "This research shows maize offers producers with entire black-and-white bull calves a real opportunity this year," says Prof Beever.
Studies on carcass quality at Bristol University showed acceptable meat quality from maize-fed cattle, he adds.
Remember to feed adequate protein
FEEDING adequate protein in maize-based diets is important to secure the best performance from finishing animals, but the type of protein is less critical.
Studies feeding maize at CEDAR, part of Reading Universitys department of agriculture, show that cattle perform better on diets formulated at 18% crude protein than one of 14%. Concentrate was fed as 18% of a mixed ration.
However, these trials used two concentrates to produce an 18% protein ration. One was high in rumen degradeable protein (RDP), based on soya and rapeseed meal, while the other was high in undegradeable protein (UDP), based on soya, rapeseed meal and fishmeal in equal amounts.
Daily liveweight gains were 1.32kg, 1.55kg and 1.58kg for the 14%, high RDP and high UDP diets, respectively. Feed conversion efficiency results showed 7.9kg of feed was needed/kg of gain with the 14% crude protein diet, but this was reduced to 7.1kg for the higher protein diets.
"Even with finishing cattle, it would appear that feed protein level is important, but there seems to be little to be gained by feeding by pass protein sources," says Prof Beever. *
MAIZE FED BEEF
• Good gains achieved.
• Bulls most efficient
• Crossbred grow faster