Effects of two different housing systems on behavior, physiology and milk yield of Comisana ewes

Two groups of 20 early-lactating Comisana ewes were used in this study, and were allocated to either an indoor or outdoor daytime environment. The indoor environment was a 3 m x 12 m straw bedded pen inside a pre-fabricated building. The outdoor environment was a 200 m2 paddock during daytime (09.00-19.00 h) with ewes being moved to the shed, as described for the indoor treatment, at night. Behavior of ewes was recorded at 14 days interval from 09.00 to 19.00 h. A phytohemagglutinin (PHA) skin test was performed at weeks 6, 11, 15 and 18 of the experiment to induce a non-specific delayed-type hypersensitivity in ewes. Jugular blood samples were taken at the beginning and at weeks 5, 10, 14 and 18 to determine endocrine and metabolic responses of animals to housing system and to changes in climatic conditions and stage of lactation. Ewe milk yield was recorded daily and individual milk samples were analyzed for milk composition, coagulating properties and somatic cell count (SCC) at 14 days interval. No differences were found between groups for endocrine and immune responses. Outdoor ewes had increased locomotor activities (P < 0.01) and decreased idling (P < 0.05) compared to indoor animals. The outdoor group had higher levels of blood creatinine (P < 0.01) and inorganic phosphorus (P < 0.05) as well as lower urea (P < 0.01) and glucose (P < 0.001) concentrations compared to the indoor group. Milk yield and composition were not changed by the housing system, though significant time x treatment interactions were found for milk constituents, with indoor-housed ewes having higher (P < 0.05) milk protein, fat and lactose concentrations during the middle of the trial. Outdoor ewes had lower SCC (P < 0.003) and pH (P < 0.001) in their milk than indoor ewes, whereas renneting parameters were not different across treatments. Results suggest that ewe welfare and productivity were not substantially affected by the housing system. The provision of feeding rations that meet the greater energy demand for maintenance is required to sustain productivity in outdoor reared sheep.