Ley crop silage in diets to fattening pigs : How does it affect pig performance, nitrogen utilization, health and behaviour?

Abstract

There is an increasing interest to use silage as a feed ingredient to pigs. The aim of this thesis was to study the effect of using silage in the diet to fattening pigs and how feeding strategy influenced pig performance, behaviour, gut health and nitrogen utilization. Two studies were performed. Study I focused on 1) pig performance, 2) behaviour and gut health and 3) nitrogen utilization and study II focused on pig behaviour and time budgets. In study I, 128 fattening pigs (30-110 kg) were fed either a commercial control feed (control) or received silage in a pellet (Pellet-S) or in a total mixed ration (TMR) containing fresh, chopped silage (TMR-Ch) or fresh, intensively treated silage (TMR-Ex). In study II, 126 growing pigs (30-70 kg) received a commercial control feed (control) or silage in a pellet (Pell-S) or fresh in a TMR with chopped silage (TMR-S). In both studies, silage replaced 20% of the dietary crude protein content (g/kg). The results in study I showed that pigs fed silage in general had a satisfying growth, but feeding fresh silage slightly reduced the daily weight gain. Pigs fed the pelleted silage had the highest daily weight gain and that feeding fresh silage slightly reduced the daily weight gain, however, pigs fed intensively treated silage performed similar to pigs fed the control diet. In study II, pigs fed TMR with fresh silage spent more and longer time performing foraging behaviours and were overall more active compared to pigs fed the pelleted silage and control diets. Feeding fresh silage reduced occurrences of gastric lesions in the gastric mucosa. Silage-based diets reduced the ammonia volatilization from the manure, which highlights the potential of using silage to reduce the environmental load from pig housing. The results support that silage is a suitable feed ingredient for fattening pigs, with potential to improve pig health and welfare.