Arantxa Villagrá

Implications of increasing ventilation rates of broiler farms to fulfill European welfare regulations on gas concentrations

Ammonia and carbon dioxide concentrations are limited in the EU when rearing density exceeds 33 kg/m2. Threshold concentrations (20 and 3,000 ppm for ammonia and carbon dioxide respectively), have been reported to be higher in literature. One of the simplest ways to reduce these concentrations through increasing ventilation rates, although this technique may lead to higher energy consumption due to ventilation and heating needs. The aim of this paper is to evaluate this extra energetic cost in a practical case in a broiler house. To this aim, a broiler house (24,000 places) located in a mild Mediterranean area (Villarreal, Castellon, Spain), was monitored for gas concentrations and ventilation rates during a whole winter cycle. A sensible heat balance was developed to determine heat needs during the cycle. Later, gas concentrations during the cycle were evaluated and when they were higher than the established limits, the extra ventilation rates needed to reduce these concentrations were calculated. The implication on heat consumption of this extra ventilation was also determined using a sensible heat balance. On average, ventilation rated had to be increased 9.87% for the whole rearing cycle. This extra ventilation implied an over energy consumption of 28.61% considering the whole cycle. Ammonia was the main contributor to these extra ventilation needs since carbon dioxide concentrations were found to be high only during the first days of the cycle. It should be considered that the interpretation of some aspects of the regulation may lead to strong modifications of these extra costs.

Assessing fear in rabbits. Preliminary results

Fear has been assessed in several species throughout different tests. Two of the most popular fear tests are novel object and open field test. These tests have been used in rodents or pigsbut little is known about rabbits. Thus, it is necessary to assess the validity of these tests in commercial rabbits, as well as assessing potential differences in the behavior of males, breeding does and young females. The aim of this work was to validate a novel object and an open field test in young male rabbits, multiparous does and nuliparous does, by measuring stress induced hyperthermia.

Aggressiveness testing of breeding rabbit does.

Aggressiveness can become a problem in group housed breeding rabbits and most likely becomes evident when mixing is carried out. On the other hand, animals housed in the same barn could identify their odor and this familiarity could lead to changes in behavior. The aim of this study is to determine the age at which aggression reaches the highest level in breeding does as well as the influence of the precedence of a different room. This has been performed throughout a 30 minute long resident-intruder test. Seventy four does were used in this study. Thirty-two does were tested as resident and 32 were tested as intruders. The intruders came from two different origins: 16 intruders came from cages inside the same experimental room and 16 came from an adjacent room. Aggressions were recorded during confrontations and the time at which each behavior started was recorded, as well as the latency to the first aggression and the latency to a fight which led to the termination of the test (more than 10 seconds). The test was carried out from 13 to 27 weeks of age. Age had a clear effect on latency to the first aggressive behavior and on latency to a strong fight and from day 130, latencies decreased by 50%. The latency to a strong fight was lower when intruders came from the same room (P<0.0001) but intruder’s origin did not have effect on latency to the first aggression.