Technical note: validation of electronic feeding stations as a swine research tool.

Electronic feeding stations (EFS) were developed to automate data collection of individual animals housed in a group environment. In order for scientists to use EFS, such as feed intake recording equipment (FIRE), in research, data recorded electronically cannot differ from data recorded on calibrated scales. The objectives of 2 studies were to determine if data recorded by 2 FIRE stations (FIRE1 and FIRE2) were different from the same data recorded by calibrated scales and determine differences between the 2 independent FIRE stations. Body weight of pigs recorded by the platform scales of both FIRE stations did not differ (P > 0.6) from calibrated scales during a 21-d comparison (study 1). The weight of calibrated check weights recorded by the platform scale of FIRE1 tended to be less (P = 0.1) than the weight of check weights during a 126-d comparison (study 2). Feed disappearance recorded by FIRE1 was greater (P < 0.01) than recorded by calibrated scales during study 2. Feed dispensed to the FIRE trough and compared with calibrated scales did not differ (P ≥ 0.17) for either FIRE station during study 2. There were no differences (P ≥ 0.15) between FIRE1 and FIRE2 for any measured variables. The FIRE stations were not recalibrated during study 1. The platform scale of FIRE2 was recalibrated during study 2 when the percentage error between calibrated check weights and the weight recorded by FIRE exceeded 2.5%. The trough scales of FIRE1 and FIRE2 were recalibrated during study 2 when the percentage error between true weight of dispensed feed and the average recorded FIRE weight exceeded 4%. Establishing more stringent criteria for recalibration may have reduced differences among weights recorded by calibrated scales and weights recorded by FIRE. These data suggest that FIRE stations can be used in research; however, adequate verification procedures and recalibration criteria must be followed to ensure accuracy of data.

Effect of essential oil compound on shedding and colonization of Salmonella enterica serovar Heidelberg in broilers.

The objectives of this study were to determine the effect of an essential oil blend (EO; carvacrol, thymol, eucalyptol, lemon) administered in drinking water on the performance, mortality, water consumption, pH of crop and ceca, and Salmonella enterica serovar Heidelberg fecal shedding and colonization in broiler birds following Salmonella Heidelberg challenge and feed withdrawal. Chicks were randomly assigned to water treatments containing 0.05, 0.025, or 0.0125% EO or untreated controls. Treatments were administered in drinking water on 0 to 7 and 35 to 42 d. One-half of the chicks were challenged with Salmonella Heidelberg and placed in pens with unchallenged chicks on d 1. Performance, mortality, water consumption, and pH were determined during the 42-d study. Prevalence of Salmonella Heidelberg was determined on drag swabs (0, 14, and 42 d) and in the ceca and crops (42 d). The 0.05% EO administered in drinking water significantly (P < 0.05) reduced Salmonella Heidelberg colonization in crops of challenged birds, significantly lowered the feed conversion ratio, and increased weight gain compared with controls. The 0.025% and 0.015% EO in drinking water significantly lowered the feed conversion ratio and increased weight gain compared with controls, but did not significantly reduce Salmonella Heidelberg colonization in the crops. The EO in drinking water did not significantly reduce Salmonella Heidelberg colonization in ceca or fecal shedding in broilers. The EO used in the study may control Salmonella Heidelberg contamination in crops of broilers when administered in drinking water and therefore may reduce the potential for cross-contamination of the carcass when the birds are processed.

Relationship between weaning and secretion of luteinizing hormone, cortisol and transcortin in beef cows.

The effects of suckling on secretion of luteinizing hormone, cortisol and transcortin were investigated in anovulatory postpartum cows. On d 35 postpartum, calves were separated from 12 cows to prevent suckling and eight calves continued to suckle their dams ad libitum. Between 35 and 41 d postpartum, samples of jugular blood were collected every 15 min for two periods of 6 h/d. In non-suckled cows, frequency of pulses and basal luteinizing hormone increased but amplitude of pulses did not change. Concentrations of total cortisol in serum of cows were not altered during 3 d after weaning calves and did not differ among intervals before, during and after a suckling event. Affinity of transcortin for cortisol was not affected by postpartum interval or treatment. Capacity of transcortin to bind cortisol tended to increase after weaning. We found no evidence to support the hypothesis that suckling reduces binding capacity of transcortin or increases unbound cortisol. Differences in preovulatory secretion of luteinizing hormone between suckled and non-suckled cows could not be accounted for by differences in secretion of cortisol. In beef cows that are fed to satisfy requirements for energy and have average body condition, we conclude that negative modulation of luteinizing hormone by suckling is not mediated by cortisol.