Effects of roughage source, amount, and particle size on behavior and gastrointestinal health of veal calves.

The European Union 1997 Directive, stipulating that veal calves should be fed a minimum of 50 to 250 g of fibrous feed from 8 to 20 wk of age, is vague. A fibrous feed ration maximum of 250 g has been implicated in welfare issues, namely the occurrence of abnormal oral behaviors and poor gastrointestinal health. Past research suggests that this amount is insufficient to prevent the development of abnormal oral behaviors and enabling good rumen development. Different sources and particle sizes of roughage could lead to very different welfare outcomes. In a 3×2 × 2 factorial design, 240 group-housed calves (10±1 d; 46.1±0.1 kg) were fed different roughage sources (straw, maize silage, or maize cob silage; the latter 2 were dried and provided no extra moisture compared with straw) in 2 amounts (250 or 500 g of dry matter per day), and 2 particle sizes (chopped or ground). Roughage was supplemented to milk replacer (MR) from 2 wk after arrival. In addition, 60 calves were fed 1 of 3 additional control treatments: MR only (n=20), MR plus an iron supplement (n=20), or MR plus ad libitum hay (n=20). Oral behaviors were recorded using instantaneous scan sampling at 2-min intervals for 2 h in 3 periods per day, at 12 and 22 wk of age. Calves were slaughtered at 24 wk of age and rumen and abomasal health parameters were recorded. Limited provision of straw resulted in behavior comparable with that from unlimited provision of hay, with reduced tongue playing and oral manipulation of the environment, as well as increased chewing compared with diets with no roughage supplement. Straw prevented ruminal hairballs, but impaired rumen development and increased abomasal damage. A higher ration of roughage increased chewing (12 wk), decreased oral manipulation of the trough (12 and 22 wk) and the pen (22 wk), and increased rumen weight. However, more roughage led to increased abomasal damage for certain parameters. Longer feed particles had no obvious benefits for behavior, but decreased hairball prevalence. Overall, unlimited hay had the highest benefit for both behavior and gastrointestinal health. Adding iron to the MR did not alter behavior or gastrointestinal health compared with MR without iron supplement. This study demonstrated that different roughage sources, amounts, and particle sizes have different effects on veal calf behavior and gastrointestinal health, and hence on veal calf welfare.

Lean meat prediction with HGP, CGM and CSB-Image-Meater, with prediction accuracy evaluated for different proportions of gilts, boars and castrated boars in the pig population.

Prediction equations for the percentage lean meat in pig carcasses in The Netherlands were derived for the Hennessy Grading Probe 7, Capteur Gras/Maigre--Sydel and CSB-Image-Meater. Because castrated males are expected to vanish from the Dutch pig population in the near future, accuracy of prediction was evaluated for different scenarios representing a wide range of different proportions for entire males, castrated males and females in the Dutch pig population. The prediction equations for the instruments are in compliance with the EC regulations for prediction accuracy for the different scenarios. So, these equations will remain valid when castrated males are (gradually) removed from the Dutch slaughter population. Results of this study are of interest for researchers from countries or areas contemplating the use of one of the aforementioned instruments. The statistical approach for evaluation of prediction accuracy is of particular interest when changes in proportions of important subpopulations in the target population are foreseen.

Effects of genetic origin and social environment on behavioral response to manual restraint and monoamine functioning in laying hens.

Purebred laying hen lines of White Leghorn (WL) origin have been found to be more flighty and to show more feather pecking than lines of Rhode Island Red (RIR) origin. It has been found, however, that when RIR birds were housed together with WL birds, RIR birds became more flighty and those mixed groups developed more feather damage than pure-line cage-housed groups. It is unknown, however, whether this effect of social environment is accompanied by changes in stress-related behavior and neurophysiological activity, which are assumed to be associated with increased feather damage. The objective of this study was therefore to investigate the effects of genetic origin (WL or RIR) and social environment (mixed or pure groups) on behavioral response to manual restraint and monoamine functioning. Monoamine functioning was measured by brain serotonin (5-HT) and dopamine turnover. Furthermore, correlations between 5-HT turnover in the brain and peripheral measures of 5-HT in the blood were calculated. Experimental birds, housed either with other birds from the same genetic origin (pure groups) or with both RIR and WL birds (mixed groups) from hatching onward, were subjected to a manual restraint test at 47 wk of age. The WL birds struggled less during restraint and had higher dopamine and 5-HT turnover levels after restraint than did RIR birds. The WL birds also showed higher levels of platelet 5-HT uptake than did RIR birds. No effects of social environment were found. Blood and brain 5-HT measures were found to be correlated, with correlations ranging from 0.34 to 0.57, which seems to offer opportunities for less invasive peripheral indicators of 5-HT activity. In conclusion, genetic origin, but not social environment, affected the behavioral response to manual restraint and monoamine functioning in laying hens.

Evaluation of three commercial enzyme-linked immunosorbent assays for the detection of antibodies against Salmonella spp. in meat juice from finishing pigs in Spain.

The control of animal salmonellosis is considered as a major objective in Europe and indirect ELISAs will be important tools for the implementation of control programs for this infection in pigs. We analyse the results yielded by three commercial ELISAs (Herdcheck Swine Salmonella, SALMOTYPE Pig Screen, and PrioCHECK Salmonella) on meat juice samples from a population of slaughter pigs of Aragon, NW Spain, to assess their efficacy using traditional and latent-class approaches. Overall, the Herdcheck Swine Salmonella detected more Salmonella-infected pigs than the other two tests, but its relative sensitivity was low (65.9%). A similar result was observed when only serotypes detectable by this test were considered (69.1%). When a Bayesian approach was used the Herdcheck Swine Salmonella showed also the highest overall accuracy (sensitivity = 88% and specificity = 74%). Our results suggest that a relatively small proportion of the observed prevalence in herds would be explained by using these ELISAs. Also, this study points out that when different ELISA tests are used within the same herd, results may differ substantially. Thus, caution is advised if it is decided to use these assays for herd health classification in Spanish Salmonella control programs.

The benzodiazepine brotizolam reduces fear in calves exposed to a novel object test.

The present study examined the effects of the intravenous administration of the anxiolytic drug brotizolam on the behavioral and physiological responsiveness of calves to novelty in a dose response fashion. Holstein Friesian heifer calves (39-41 weeks of age; body weight 200-300 kg) received an intravenous injection of either a vehicle control (12 calves) or one of four doses of brotizolam (8 calves per dose): 0.0125, 0.05, 0.2 and 0.8 mg/100 kg body weight. They were then individually subjected to a 'combined' test involving exposure to a novel environment (open field, OF) for 5 min followed by the sudden introduction of a novel object (NO) that remained in place for a further 10 min. Behavioral, heart rate and plasma cortisol responses were recorded in all animals. Compared to vehicle treatment, the highest dose of brotizolam dose-dependently and significantly increased the time spent in locomotion and the distance travelled near the NO, as well as the time spent in contact with the NO. In addition, post-test plasma cortisol concentrations changed in a dose-dependent manner over time: they decreased between 0 and 10 min after the test in calves that had received the two highest doses of brotizolam, whereas they increased in vehicle-treated and low-dosage calves. There were no effects of brotizolam on vocalization or locomotion during the OF phase of the test or on vocalization following introduction of the NO. These findings strongly support the notion that interaction with a novel object in a novel arena represents a behavioral index of fear and fearfulness in calves, and that vocalization and locomotion in an OF reflect other independent characteristics.

Adaptation to social isolation. Acute and long-term stress responses of growing gilts with different coping characteristics.

The present experiment studied the acute and long-term stress responses of reactive and proactive prepubertal gilts to social isolation. Gilts with either reactive or proactive features were identified according to behavioral resistance in a backtest at a young age (2-4 days), respectively being low (LR) and high resistant (HR) in this test. At 7 weeks of age, 12 gilts of each type were socially isolated. Initially, isolation was stressful for both types of gilts, as shown by increased cortisol concentrations and decreased body temperatures. Moreover, both types reacted with increases in exploration and vocalizations. Stress responses to isolation, however, differed in magnitude and/or duration between LR and HR gilts, which was in line with expected reaction patterns on the basis of preferred ways of coping. The cortisol response to isolation was higher in LR gilts, and they generally showed more explorative behavior. HR gilts seemed to be more engaged in walking/running behavior in the first hour after isolation, they generally vocalized more and their noradrenaline excretion in urine was higher at 3 weeks after the start of isolation. Several responses to isolation in the longer term pointed to a prolonged higher general state of stress of HR gilts. Body temperature in HR gilts, for instance, did not recover during 3 weeks of isolation, but values returned to "normal" within 1 day in LR gilts. At 1 week of isolation, relatively high parasympathetic responsivity to novelty was observed in HR gilts, probably due to stress-related high sympathetic reactivity. A shift in percentages of leucocyte subsets, typically occurring under conditions of stress, only developed in HR gilts during isolation. Finally, gastric ulceration was found in one HR gilt, but did not occur in LR gilts. To conclude, LR and HR gilts differed in their strategies to adapt to social isolation, and especially for HR gilts, this procedure seemed to become a chronic stressor.

The circadian rhythm of salivary cortisol in growing pigs: effects of age, gender, and stress.

This experiment was designed to examine circadian rhythmicity of cortisol in saliva of growing pigs, in relation to age, gender, and (time of) stressor application. Additionally, the acute cortisol response to a stressor was studied. Five groups, each consisting of 3 barrows and 3 gilts, were involved in the experiment. In a Control Group, saliva samples were taken at 1-h intervals at 12, 16, 20, and 24 weeks of age. Within 1 week, rhythmicity of cortisol was assessed during two 24-h spans (Monday and Friday). Rhythm characteristics were evaluated by cosinor analysis, describing the rhythm by several parameters. In 2 groups at 12 weeks and 2 other groups at 20 weeks of age, a stressor was applied (4 h of isolation) on Thursday morning or evening. Again, rhythmicity was assessed on Monday and Friday by sampling at 2-h intervals. Acute cortisol effects were studied by sampling at several time-points during isolation. Between 12 and 24 weeks of age, basal cortisol concentrations decreased and a rather stable and adult circadian rhythm was reached at 20 weeks of age. Average basal cortisol concentrations were higher in barrows than in gilts. Furthermore, after isolation, the amplitude of the rhythm was increased in barrows but was unchanged in gilts. The rhythm was more unstable and the maximum value tended to shift only after evening isolation. Stressor timing, but also age, was found to affect average cortisol concentrations. Moreover, stressor timing was important for the acute cortisol response: the increase was higher in the morning. The results of this study emphasize the importance of considering the circadian rhythmicity of cortisol, in relation to age, gender, and (time of) stressor application, when studying the cortisol response of animals to stressors.