Epsilon Open Archive

Abstract

Successful feeding strategies of periparturient ewes and growing lambs are essential in intensive indoor lamb production. This thesis evaluated the effects of chopping grass silage and of mixing silage with concentrate on feed intake, dietary selection, chewing behaviour, faecal particle size and performance in pregnant and lactating ewes and in suckling and finishing lambs. In addition, the effects of silage digestibility on feed intake, dietary selection and performance in pregnant and lactating ewes and in suckling lambs were evaluated. Lastly, the effects of feeding whole crop maize silage, harvested at different maturity stages, as the sole forage or combined with grass silage on feed intake, dietary selection, chewing behaviour, faecal particle size and performance in finishing lambs were evaluated.

Three experiments were conducted at Götala Beef and Lamb Research Centre, SLU, Sweden. The results show that by chopping grass silage prior to feeding pregnant and lactating ewes, eating time and dietary selection were decreased whereas rumination time was increased. Chopping of silage also increased growth rate of finishing lambs. Mixing of silage and concentrate increased feed intake in lactating ewes and growth rate of suckling lambs, indicating a higher milk yield of the ewes. Furthermore, improved digestibility of grass silage, due to earlier harvest, increased silage intake and body weight in pregnant and lactating ewes and reduced loss of body condition in lactating ewes. Early harvested silage also decreased concentrate intake and increased the growth rate of the suckling lambs, indicating a higher milk production of the ewes. To optimize feed efficiency, silage of maize harvested at dent stage of maturity should be fed as the only forage, whereas maize harvested at the dough stage could be fed in a mix with grass silage. Feeding maize silage as the sole forage decreased eating and rumination time per unit of intake. Lambs selected particles between 1 and 8 mm and sorted against particles high in fibre. Furthermore, to maximize lamb growth rate, the protein content and quality seem to be the most important dietary factors.

In summary, to maximize production output in intensive lamb production by optimizing feeding, highly digestible chopped grass silage or maize silage harvested at dent stage of maturity should be fed mixed with concentrate.