Effects of replacing grass silage with either maize or whole-crop wheat silages on the performance and meat quality of beef cattle offered two levels of concentrates

Abstract

A randomised design involving 66 continental cross beef steers (initial live weight 523 kg) was undertaken to evaluate the effects of the inclusion of maize or whole-crop wheat silages in grass silage-based diets on animal performance, carcass composition, and meat quality of beef cattle. Grass silage was offered either as the sole forage or in addition to either maize or whole-crop wheat silages at a ratio of 40:60, on a dry matter (DM) basis, alternative forage: grass silage. For the grass, maize, and wholecrop wheat silages, DM concentrations were 192, 276, and 319 g/kg, ammonia-nitrogen concentrations were 110, 90, and 150 g/kg nitrogen, starch concentrations were not determined, 225, and 209 g/kg DM and in vivo DM digestibilities were 0.69, 0.69, and 0.58; respectively. The forages were offered ad libitum following mixing in a paddle type complete diet mixer wagon once per day, supplemented with either 3 or 5 kg concentrates per steer per day, in two equal feeds, for 92 days. For the grass, grass plus maize and grass plus whole-crop wheat silage-based diets food intakes were 8.38, 9.08, and 9.14 kg DM per day, estimated carcass gains were 514, 602, and 496 g/day and carcass weights were 326, 334, and 325 kg; respectively. Altering the silage component of the diet did not influence carcass composition or meat eating quality. Increasing concentrate feed level tended ( P ¼ 0.09) to increase estimated carcass fat concentration and increased sarcomere length ( P , 0.05), and lean a* ( P , 0.01), b* ( P , 0.05), and chroma ( P , 0.01). There were no significant silage type by concentrate feed level interactions for food intake, steer performance, carcass characteristics or meat eating quality. It is concluded that replacing grass silage with maize silage increased carcass gain, and weight due to higher intakes, and improved utilisation of metabolisable energy. Whilst replacing grass silage with whole-crop wheat silage increased live-weight gain, the reduced dressing proportion resulted in no beneficial effect on carcass gain, probably due to increased food intakes of lower digestible forage increasing gut fill. Meat quality or carcass composition were not altered by the inclusion of maize or whole-crop silages in grass silage based diets.

Effects of replacing grass silage with maize silages differing in inclusion level and maturity on the performance, meat quality and concentrate-sparing effect of beef cattle

“…The weights of perinephric plus retroperitoneal fat were recorded for every animal during the dressing procedure. All carcasses were changed from achilles suspension at 45 min postmortem to suspension from the aitch bone (tenderstretch) and chilled under standard commercial conditions as described by Keady et al (2007). At 48 h postmortem, the carcass was quartered between the 10th and 11th rib, and the depth of subcutaneous fat was measured at points 0.25, 0.50 and 0.75 over the m. longissimus dorsi (LD).…”

“…Marbling of the LD and the area of the LD at the 10th rib on each side of the carcass was determined as described by Keady et al (2007). Sampling for sarcomere length and measurement by laser diffraction was as described by Keady et al (2007).…”

“…Sampling for sarcomere length and measurement by laser diffraction was as described by Keady et al (2007).…”

“…The LD was removed from the fore-rib joint, on day 7 postmortem, for meat quality assessment. The remainder was retained for dissection into lean, fat and bone as described by Keady et al (2007). The composition of the carcass of each animal was estimated from the composition of its fore-rib joint using the equations given by Steen and Robson (1995) for animals that were considered to be of predominantly Charolais breeding; adjusted versions of these equations, as given by Steen and Kilpatrick (2000), were used for the Simmental-cross animals and, as given by Steen and Kilpatrick (1995), for Limousin and Blonde d'Aquitaine crosses.…”

“…In beef production, when the price of concentrate relative to animal product and to forage is high, one of the potential benefits of including maize silage in the diet of finishing cattle is the ability to maintain animal performance while reducing the level of concentrate supplementation required (Keady et al, 2007), consequently reducing the costs of production. The objective of the present study was to evaluate the effects of level of inclusion of maize silages, differing in maturity at harvest, on animal performance, carcass composition and meat quality of beef cattle.…”