Forages for growing pigs: partition of digestion and nutritive value
1997
Andersson, C. (SLU, Uppsala (Sweden). Inst. foer Husdjurens Utfodring och Vaard)
Diets for pigs are largely based on highly digestible and energy-rich cereals as the dominating energy source. Forages can be widely grown and could be an interesting component for balancing feed intake and lowering competition between animals in addition to improving the well-being by providing bulky feedstuffs and thereby increasing satiety. The aim of the present thesis was to study the partition of apparent digestion along the gastro-intestinal tract of the growing pig fed a barley-based diet with forage meal inclusing and to assess the nutritive value of lucerne, white clover, red clover and perennial ryegrass meals. The purpose was further to study digesta sampling technique at the terminal ileum. Pigs have a limited capacity for precaeced digestion of dietary fibrous components. Increasing inclusion of forage meals in barley-based diets reduced the ileal as well as the total tract digestibility of dietary nutrients and energy. The decrease in digestibility was more pronounced at the terminal ileum than in the total tract. With forage meal inclusion, there was an increase in the proportion of the total tract digestible energy released in the hindgut. The pigs had a high capacity to digest forage fibrous components in the hindgut. When using a post valvular T-cannula on pigs fed three times daily, a valid estimate of the ileal digestibility for a 24 h period can be based on representative ileal digesta samples collected from an 8 h interval between feeding occasions. The digestibility of energy at the terminal ileum as well as in the total tract was most efficiently predicted by the dietary content of neutral detergent fibre. The estimated metabolizable energy content in the total tract was 10.5, 9.5, 6.6, and 5.9 MJ/kg DM in white clover, red clover, lucerne and perennial ryegrass meal, respectively.
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