Feeding maize silage to lambs increases intakes and daily liveweight gains
Take Home Message: Lambs finished on maize silage compared with grass silage will have an increased intake and liveweight gain, particularly at lower levels of supplementary feeding.
High quality maize silage is an ideal forage for finishing lambs indoors, achieving higher intake characteristics and increasing daily live weight gain by up to 50g/d compared to lambs offered medium-quality grass silage.
“However the benefits in lamb performance decrease significantly when diets contain high levels of concentrates,” the Hillsborough-based Agri-Food and Biosciences Institute’s Ronald Annett told delegates at this year’s British Society of Animal Science’s annual conference, held at Queen’s University, Belfast.
Within sheep systems in the UK and Ireland it is common for hill lambs to be housed late in the season and finished on high grain diets due to inadequate supplies of grass. “However, due to a number of factors, concentrate feed costs have increased significantly in recent years so there is a need to investigate lower cost alternatives,” said Dr Annett, explaining the rationale behind his team’s work.
Forage maize has increased in popularity over the past 10 years and offers some opportunities to reduce forage costs on mixed beef/sheep farms, with the potential for high dry matter yields of high quality material from a single harvest.
“But there is limited information on supplementation strategies for lambs offered maize silage. So we set out to investigate the performance and carcass characteristics of lambs finished on grass silage or maize silage at two contrasting levels of concentrates,” he added.
Sixty crossbred lambs of mixed breeds, with a mean age of 217 days and a mean live weight of 35kg, were allocated to four groups. Lambs were housed in groups of six and offered ad-lib grass silage (G) or maize silage (M) plus concentrates. Concentrates were offered to achieve a high or low proportion of forage in the diet, giving a total of four treatments.
Intake of silage and supplement were recorded daily. Lambs were weighed fortnightly until they reached their target slaughter weight of 44kg. Cold carcass weight, dressing proportion and grade were recorded at the point of slaughter.
Carcass conformation and carcass fatness were also both scored.
“Intake of maize silage was 17% higher than grass silage for lambs on the high forage diet, and 14% higher on the low forage diet,” said Dr Annett. “And total DM intake increased by 15% when lambs were offered maize silage rather than grass silage. Consequently, daily live weight gain was 34g/d higher for maize silage-fed lambs.”
Reducing the forage proportion from 0.80 to 0.50 decreased the intake of grass silage and maize silage by 17% and 14% respectively, but increased total DM intake by 32% and average daily live weight gain by 53g/d.
“Finishing diet had no effect on carcass fatness, but with grass silage-fed lambs only, carcass conformation increased and dressing proportion tended to increase as the proportion of forage in the diet increased,” he added.
Presented to the British Society of Animal Science Annual Conference, 12-14 April, 2010, Queen’s University, Belfast.
Annett RW and Carson AF: “Effects of silage type and proportion in the diet on the growth and carcass characteristics of finishing lambs.”
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