Welfare studies are increasingly involving the application of Precision Livestock Farming (PLF) sensors, rather than the use of animal-based indicators directly assessed. PLF technology has the advantage to constantly monitor behavior over a long period of time, thus enabling the assessor to identify changes in animal time budgets in real-time. In calves, lying behavior is essential: new-borns have been reported to spend 70–80% of their daily time lying. Growing up, calves progressively reduce the time spent lying; at 3 months, lying behavior occupies around the 50% of their day. Several studies emphasize how lying behavior can be considered as a potential indicator of positive welfare in ruminants, including calves. The aim of this study was to critically revise scientific literature regarding the application of precision livestock farming technologies to measure lying, rest and sleep behaviors in dairy calves. A systematic literature search based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was conducted through Scopus and Web of Science databases to retrieve full peer-reviewed papers written in English on different PLF technologies applied to measure lying behavior in dairy calves. Literature search retrieved 731 records. After duplicate removal and the application of inclusion criteria, a total of 16 papers were considered eligible for the evaluation. Different PLF technologies and approaches were reported to be used: triaxial accelerometers, machine learning with accelerometer data, computer vision with video cameras, wearable cameras and real-time locating system. Most of the papers (10 out of 16) reported the use of accelerometers, placed on different parts of body of the animal (hind leg, neck, head, ear). Considering the importance that lying behavior has for maintaining homeostasis and development of calves, the possibility to monitor it constantly and reliably with PLF technology would certainly provide a better understanding of calves’ behavior and positive welfare. However, our findings underline PLF technologies still show some practical limitations. Therefore, we must ensure that the sensors are valid and reliable before applying them in practice to detect changes that can be linked with welfare status of calves.

Immunocastration has been pointed out as an alternative to surgical castration; though, most of the scientific studies were performed in light pig production. This study aimed to evaluate the effect of immunocastration on animal welfare in heavy pig production through the evaluation of behaviour and body lesions. A total of 188 commercial-hybrid pigs were randomly allocated into two treatment groups: surgical castration (SC) and immunocastration with Improvac^® (IC). Data on behaviour, body lesions, and salivary testosterone levels were collected the day before each vaccination at 15, 22, 32, and 36 weeks of age. IC and SC pigs were slaughtered at 40 and 41 weeks of age, respectively; productive and carcass traits data were also collected. Considering productive performance, our results confirmed that IC pigs grew faster and presented a higher weight at slaughter. A critical period for pig welfare was observed before 32 weeks: testosterone concentration and body lesion score were significantly higher in IC pigs compared to SC pigs; active behaviours were significantly more frequent in IC at 15 weeks. Immunocastration may represent a suitable alternative to surgical castration with profitable productive performances, whereas the impairment of welfare during the period before the effective vaccination should be further investigated as a potential critical aspect in heavy pig production.

Efforts to enhance animal welfare have led to the investigation of alternative methods of performing surgical castration on young pigs that induce stress and anxiety. This study was conducted to establish the efficacy of immunocastration in heavy pigs, with non-invasive diagnostic indicators being salivary cortisol and testosterone levels. At 225 days, a significant difference was noted in the cortisol levels of pigs in the treatment groups, with the immune-castrated (IC) recording higher levels than the surgically castrated (SC) animals. Furthermore, 196-day and 225-day-old IC pigs had remarkably elevated testosterone amounts. The changes that were seen to be significant after immunocastration indicate that the use of salivary tests can be a good way of evaluating how effective this alternative method is. Among SC pigs, a significant positive relationship was found between salivary cortisol and salivary testosterone concentrations at 225, 240, and 268 days. Moreover, no association was observed in IC animals. These findings signal that the hormonal levels and their interactions are related to different physiological reactions of pigs to immunological and surgical castration. The results underline the significance of salivary cortisol and testosterone as stress and hormonal balance indicators in heavy pigs with immunocastration. This study provides insights into the complex hormonal reactions to stress post-castration and emphasizes the need for further research to enhance animal welfare practices. Overall, salivary testing offers a practical approach to evaluating immunocastration efficacy and monitoring pig health and well-being.

The Italian pig sector requires heavy pigs (raised for at least nine months and slaughtered at >160 kg). In order to avoid boar taint and lower the impact on welfare, immunocastration provides an alternative to surgical castration. This study investigated the effects of immunocastration compared to surgical castration on the chemical composition and fatty acid profile of loins (longissimus dorsi muscle) and adipose tissue in Italian heavy pigs raised for dry-cured ham. Twenty-four male pigs were subjected to surgical castration (n = 12) or immunocastration (n = 12). Carcass parameters were monitored at slaughter, and samples of longissimus dorsi muscle and subcutaneous fat were analysed. This study showed no significant differences in carcass characteristics and proximate composition of fresh meat. However, variations were observed in the fatty acid profiles of meat and adipose tissue between groups. Notably, saturated fatty acids, particularly stearic acid (18:0), were higher in the intramuscular fat (IMF) of the immunocastrated pigs compared to the surgically castrated pigs. Conversely, monounsaturated fatty acids, predominantly oleic acid (18:1n-9), were higher in the IMF from the surgically castrated pigs compared to the immunocastrated pigs. While immunocastration may offer benefits in terms of animal growth and carcass composition, it could lead to unfavourable lipid changes in fresh loin meat for Italian heavy pigs.

Pair housing has been proven to improve calves’ welfare during the pre-weaning phase, potentially promoting positive emotions. Based on the emotional valence hypothesis, according to which positive emotions are mainly processed in the left brain hemisphere, infrared thermography (IRT) may detect changes in eye temperature, particularly thermal asymmetries. This study aimed to evaluate whether pair-housed calves presented ocular thermal asymmetry, compared to individually housed calves during the pre-weaning phase. Fifty-six Friesian female calves from two commercial dairy farms were enrolled and housed either individually or in pairs from birth until 8 weeks of age. IRT images of the lacrimal caruncle of both eyes were collected at 7, 21, 35, and 56 days of age. A linear mixed model tested the effects of housing, farm, year, and timepoint. No significant effect of pair housing on ocular asymmetry emerged, while absolute eye temperatures were significantly higher in pair-housed calves. Moreover, eye temperature declined over time, suggesting reduced arousal and habituation with age. Although the lateralization hypothesis was not confirmed, the study offers insights into IRT for assessing calf emotions and supports further investigation in positive contexts to better explore links between housing, emotional valence, and brain activity.

Lying behaviour reflects cattle welfare response. This study aimed to investigate changes in salivary profiles and production variables based on lying time in dairy cows to identify potential biomarkers of rest-related changes. Over a three-month period, lying time was monitored in 15 healthy commercial dairy cows using accelerometric collars. Saliva samples were analyzed for relevant biomarkers. The LMM showed that salivary cortisol (β = 0.481, 95% CI: 0.204–0.758, p = 0.001) and total adenosine deaminase (tADA, β = 0.011, 95% CI: 0.005–0.017, p < 0.001) were positively associated with daily lying time, whereas creatinine kinase (CK) was negatively associated with daily lying time (β = −0.015, 95% CI: −0.030 to −0.001, p = 0.035). Metabolic stress can drive cows to prioritize lying, revealing a coping response to sub-optimal welfare. Increased salivary tADA reflects inflammatory conditions that alter animal behaviour by enhancing lying time. Increasing CK indicates muscle tissue injury, and physical strain may be due to acute restlessness or sustained standing. The findings suggest that changes in lying behaviour may be associated with changes in salivary analytes. The results are encouraging but require validation in larger and more diverse populations before routine application in dairy welfare assessment.