A 6-wk trial was performed with thirty-six lactating Comisana ewes during the summer of 2001. The animals were divided into three groups of 12, which were designated low (LVR), moderate (MVR), and programmed (PROGR) ventilation regimens. In LVR and MVR rooms, fans provided 10 ventilation cycles of 12.5 and 25 min/h, respectively, whereas in the PROGR room, the fan was programmed to operate at 30°C air temperature and 70% relative humidity. Mean ventilation rates were 33, 66, and 173 m³/h per ewe in LVR, MVR, and PROGR rooms. Air concentrations of microorganisms and dust and of gaseous pollutants were measured twice weekly. Respiration rate and rectal temperature were monitored throughout the trial at 1430. Behavioral traits of ewes were recorded once per week from 0930 to 1230. Cell-mediated immune response to phytohemagglutinin at d 3, 20, and 40 and humoral response to chicken egg albumin at d 11, 21, 30, and 40 were determined. At d 37, ewes were injected with 2 IU porcine ACTH/kg body weight^0.75 and subjected to blood sampling for evaluation of cortisol concentrations immediately before and 1, 2, and 4 h after ACTH injection. Milk yield was recorded daily. Individual milk samples were analyzed weekly for composition and renneting parameters and fortnightly for bacteriological characteristics. Averages of temperature-humidity index values were 78.9, 76.8, and 74.5 in LVR, MVR, and PROGR rooms, respectively. The LVR and MVR treatments resulted in higher NH₃ and CO₂ air concentrations than PROGR treatment (P < 0.05). The LVR and MVR ewes had higher rectal temperatures than PROGR ewes (P = 0.001). LVR animals also exhibited higher idling compared to PROGR (P < 0.01) and lower feeding times than MVR (P < 0.05) and PROGR animals (P < 0.01). Ewes under the LVR treatment displayed significant lower averages of antibody titers and higher plasma cortisol levels than PROGR (P < 0.01) and MVR ewes (P < 0.05) 60 min after ACTH injection. The LVR treatment resulted in lower yields of milk (P < 0.01) and reduced feed efficiency (P < 0.01) than PROGR treatment. Results suggest that a fan-ventilated system, providing ventilation cycles during the warmest hours of the day and the night at a mean ventilation rate of 66 m³/ewe per hour, may sustain the performance and welfare in lactating ewes raised in warm climates during summer. A ventilation regimen, programmed to operate over upper critical air temperature and relative humidity, may be economically unattractive under these conditions. Copyright © 2002. . Copyright 2002 Journal of Animal Science

Changes induced by twin and single lambing in the immune response of 16 periparturient Comisana ewes were studied. Cell-mediated immune responses were evaluated by means of skin tests performed from 3 wk before and up to d 35 after parturition. At d 21 and 7 before lambing, the sheep received an intramuscular injection of the antigen keyhole limpet hemocyanin (KLH), to which the animals had not been previously exposed, to determine their humoral immune response. Starting 3 wk before lambing and up to d 35 postlambing, the ewes were sampled to determine the plasma concentrations of anti-KLH antibody (IgG), IL-6, and IL-1 beta. From parturition through d 35 postpartum, individual milk samples were collected for determination of anti-KLH IgG titers and IL-6 and IL-1beta concentrations by means of a capture ELISA. The number of lambs born affected IL-6 concentrations in ewe plasma; IL-6 secretion always was higher in ewes birthing twins than in single-lambing ewes. Apart from the number of lambs born, the concentrations of plasma IL-6 in ewes were higher at lambing than at d 21 antepartum and at d 35 postpartum. An interaction of number of lambs born x time of sampling was observed for plasma antibody titers to KLH. The IgG concentrations were significantly higher in single-bearing ewes than in twin-bearing ewes before parturition and were very similar across groups after parturition. A time effect was found for the cell-mediated immune response and for anti-KLH IgG concentrations in milk, such that at parturition, cellular responses were lowest, and the anti-KLH IgG concentration was highest. A significant correlation was found for IgG titers to KLH in plasma and milk. Results indicate that IL-6 concentrations in blood can be considered a reliable indicator of stress connected to lambing and that the mammary gland is a microenvironment unrelated to blood stream with respect to interleukins expression. In contrast, a relationship was found for the IgG secretions in milk and blood, which suggests that the assessment of humoral immune status may be combined with milking routine in dairy animals.

The effects of ventilation on air quality, and on the welfare and production performance of dairy ewes were assessed in a 6-wk trial conducted during the winter of 2002. Thirty-six midlactation Comisana ewes were divided into three groups of 12, which were randomly balanced for parity, time of lambing, and number of lambs suckled. Treatments were low (LOV), moderate (MOV), and programmed ventilation regimen (PROV). In LOV and MOV rooms, fans provided 10 ventilation cycles of 40 min each at a fan speed of 1 and 2 m/s, respectively. In the PROV room, the fan was programmed to maintain a 70% relative humidity. Mean ventilation rates were 23, 47, and 73 m3/h per ewe in LOV, MOV, and PROV rooms, respectively. Air concentrations of microorganisms and dust, and of gaseous pollutants were measured twice weekly. Cell-mediated immune response to phytohemagglutinin at d 1, 21 and 42, and humoral response to chicken egg albumin at d 11, 21, 30, and 40 were determined. At d 39, ewes were injected with 2 IU of porcine adreno-corticotropic-hormone/kg body weight(0.75), and subjected to blood sampling for evaluation of cortisol concentrations immediately before and 1, 2, and 4 h after adreno-corticotrophic-hormone injection. Milk yield was recorded daily. Individual milk samples were analyzed weekly for composition, renneting parameters, and somatic cell count. The LOV treatment resulted in higher air concentrations of NH3 and CO2 than the MOV and PROV treatments. Greater amounts of total and respirable dust were found in the PROV room than in the LOV and the MOV rooms. The LOV ewes had lower milk yield than the PROV ewes, lower milk casein content, and higher rate of clot formation than the MOV and PROV ewes. The ventilation regimen did not affect the immune and endocrine responses of the ewes. Results suggest that an intermittent ventilation regimen, providing a mean ventilation rate of 47 m3/h per ewe at a fan speed of 2 m/s, is required to sustain the yield and cheese-making ability of ewe milk during the winter season.

The effects of ventilation regimen on air quality, and on the welfare and production performance of thirty-six Comisana ewes were assessed in a 6-week trial conducted during the summer of 2002. Animals were divided into three groups of 12, and subjected to the following treatments: low ventilation regimen providing a mean ventilation rate (VR) of 35 m³/h per ewe, split in 30 min ventilation cycles at an air speed of 2 m/s (LOV-30); moderate ventilation regimen (VR = 70 m³/h per ewe) split in 30 min ventilation cycles at an air speed of 4 m/s (MOV-30); moderate ventilation regimen (VR = 70 m³/h per ewe) split in 60 min ventilation cycles at an air speed of 2 m/s (MOV-60). Air concentrations of microorganisms, dust, and gaseous pollutants were measured twice weekly. Respiration rate (RR) and rectal temperature (RT) were monitored throughout the trial at 0830 and at 1400. Behavioral traits of ewes were recorded twice per week from 0900 to 1200 and from 1500 to 1800. Cell-mediated immune response to phytohemagglutinin (PHA) and humoral immune response to chicken egg albumin were determined. At d 37 ewes were injected with porcine ACTH, and subjected to blood sampling for evaluation of cortisol concentrations immediately before and 1, 2 and 4 h after ACTH injection. Milk yield was recorded daily. Individual milk samples were analyzed for composition, renneting parameters, somatic cell count (SCC), and bacteriological characteristics. Averages of maximum THI were about 3 points higher in the LOV-30 and the MOV-30 than in the MOV-60 room, whereas no differences emerged in the air concentrations of dust, gaseous pollutants and microorganisms. Significant interactions of treatment x time (P < 0.05) were found for respiration rate, and for the time the ewes spent lying, idling and eating in the afternoon during weeks 2 and 3 of the study period. Significant effects of ventilation regimen x time (P < 0.05) were also observed for milk yield and milk renneting parameters, the LOV-30 ewes giving smaller volumes of milk with a deteriorated coagulating behavior than those of the MOV-60 group during the second half of the trial. No significant differences emerged in ewe immune and endocrine responses. Results show that ventilation regimen had a moderate impact on ewe behavior, physiology and production performance. This experiment suggests that the length of ventilation cycles and air speed, together with ventilation rate, are critical for efficient ventilation regimens.

Effects of ventilation regimen on the quality of ewes' milk and on proteolysis in Canestrato Pugliese cheese during ripening were studied. Cheeses were manufactured from the bulk milk of Comisana ewes subjected to three different ventilation regimens, which were designated low (LOV, 23 m³/h per ewe), moderate (MOV, 47 m³/h per ewe) and programmed ventilation regimen (PROV, 73 m³/h per ewe; fan set to maintain 70% relative humidity). Bulk milk was analysed for chemical and microbial composition, renneting parameters and plasmin-plasminogen activities. At 1, 15, 30 and 45 d of ripening, the cheeses were analysed for gross chemical composition, nitrogen fractions, and plasmin and plasminogen activities. The pH 4·6-insoluble nitrogen fractions were analysed by urea-PAGE. Free amino acid content was determined at the end of ripening. Lower concentrations of bulk milk somatic cell count (BMSCC) and of mesophilic bacteria were found in the MOV group than in the LOV and the PROV groups. A lower plasminogen (PG) to plasmin (PL) ratio (PG/PL) was observed in the MOV and PROV than in the LOV cheeses. Irrespective of treatment, PL activity in cheeses was higher at 15 d of ripening, while a sudden decrease of PL and PG activities was observed at 30 d, which was associated with a marked increase in non-protein nitrogen. The peptide profile characterized in the urea-PAGE showed a greater intensity of α- and β-CN hydrolysis in the MOV than in the PROV and LOV cheeses. The results provide evidence that a proper ventilation regimen is critical for optimizing the hygienic quality of milk and the proteolysis of Canestrato Pugliese cheese during ripening.